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Sample records for colliculus central nucleus

  1. Representation of interaural time difference in the central nucleus of the barn owl's inferior colliculus.

    PubMed

    Wagner, H; Takahashi, T; Konishi, M

    1987-10-01

    This paper investigates the role of the central nucleus of the barn owl's inferior colliculus in determination of the sound-source azimuth. The central nucleus contains many neurons that are sensitive to interaural time difference (ITD), the cue for azimuth in the barn owl. The response of these neurons varies in a cyclic manner with the ITD of a tone or noise burst. Response maxima recur at integer multiples of the period of the stimulating tone, or, if the stimulus is noise, at integer multiples of the period corresponding to the neuron's best frequency. Such neurons can signal, by means of their relative spike rate, the phase difference between the sounds reaching the left and right ears. Since an interaural phase difference corresponds to more than one ITD, these neurons represent ITD ambiguously. We call this phenomenon phase ambiguity. The central nucleus is tonotopically organized and its neurons are narrowly tuned to frequency. Neurons in an array perpendicular to isofrequency laminae form a physiological and anatomical unit; only one ITD, the array-specific ITD, activates all neurons in an array at the same relative level. We, therefore, may say that, in the central nucleus, an ITD is conserved in an array of neurons. Array-specific ITDs are mapped and encompass the entire auditory space of the barn owl. Individual space-specific neurons of the external nucleus, which receive inputs from a wide range of frequency channels (Knudsen and Konishi, 1978), are selective for a unique ITD. Space-specific neurons do not show phase ambiguity when stimulated with noise (Takahashi and Konishi, 1986). Space-specific neurons receive inputs from arrays that are selective for the same ITD. The collective response of the neurons in an array may be the basis for the absence of phase ambiguity in space-specific neurons. PMID:3668618

  2. Development of intrinsic connectivity in the central nucleus of the mouse inferior colliculus.

    PubMed

    Sturm, Joshua; Nguyen, Tuan; Kandler, Karl

    2014-11-01

    The inferior colliculus (IC) in the mammalian midbrain is the major subcortical auditory integration center receiving ascending inputs from almost all auditory brainstem nuclei as well as descending inputs from the thalamus and cortex. In addition to these extrinsic inputs, the IC also contains a dense network of local, intracollicular connections, which are thought to provide gain control and contribute to the selectivity for complex acoustic features. However, in contrast to the organization of extrinsic IC afferents, the development and functional organization of intrinsic connections in the IC has remained poorly understood. Here we used laser-scanning photostimulation with caged glutamate to characterize the spatial distribution and strength of local synaptic connections in the central nucleus of the inferior colliculus of newborn mice until after hearing onset (P2-P22). We demonstrate the presence of an extensive excitatory and inhibitory intracollicular network already at P2. Excitatory and inhibitory synaptic maps to individual IC neurons formed continuous maps that largely overlapped with each other and that were aligned with the presumed isofrequency axis of the central nucleus of the IC. Although this characteristic organization was present throughout the first three postnatal weeks, the size of input maps was developmentally regulated as input maps underwent an expansion during the first week that was followed by a dramatic refinement after hearing onset. These changes occurred in parallel for excitatory and inhibitory input maps. However, the functional elimination of intrinsic connections was greater for excitatory than for inhibitory connections, resulting in a predominance of intrinsic inhibition after hearing onset. PMID:25378168

  3. Development of Intrinsic Connectivity in the Central Nucleus of the Mouse Inferior Colliculus

    PubMed Central

    Sturm, Joshua; Nguyen, Tuan

    2014-01-01

    The inferior colliculus (IC) in the mammalian midbrain is the major subcortical auditory integration center receiving ascending inputs from almost all auditory brainstem nuclei as well as descending inputs from the thalamus and cortex. In addition to these extrinsic inputs, the IC also contains a dense network of local, intracollicular connections, which are thought to provide gain control and contribute to the selectivity for complex acoustic features. However, in contrast to the organization of extrinsic IC afferents, the development and functional organization of intrinsic connections in the IC has remained poorly understood. Here we used laser-scanning photostimulation with caged glutamate to characterize the spatial distribution and strength of local synaptic connections in the central nucleus of the inferior colliculus of newborn mice until after hearing onset (P2-P22). We demonstrate the presence of an extensive excitatory and inhibitory intracollicular network already at P2. Excitatory and inhibitory synaptic maps to individual IC neurons formed continuous maps that largely overlapped with each other and that were aligned with the presumed isofrequency axis of the central nucleus of the IC. Although this characteristic organization was present throughout the first three postnatal weeks, the size of input maps was developmentally regulated as input maps underwent an expansion during the first week that was followed by a dramatic refinement after hearing onset. These changes occurred in parallel for excitatory and inhibitory input maps. However, the functional elimination of intrinsic connections was greater for excitatory than for inhibitory connections, resulting in a predominance of intrinsic inhibition after hearing onset. PMID:25378168

  4. Quantitative analyses of axonal endings in the central nucleus of the inferior colliculus and distribution of 3H-labeling after injections in the dorsal cochlear nucleus.

    PubMed

    Oliver, D L

    1985-07-15

    Quantitative analyses of electron microscopic (EM) autoradiographs were used to identify the afferents from the dorsal cochlear nucleus in the central nucleus of the inferior colliculus (IC) in the cat. In order to localize the sources of radioactivity, material from axonal transport experiments was analyzed by means of a hypothetical grain procedure which takes the cross-scatter of beta particles into account. Measurements of the synaptic vesicles in axonal endings and a cluster analysis were used to identify different groups of endings. In order to determine which types of endings arise in the dorsal cochlear nucleus, axonal endings labeled after axonal transport and unlabeled endings were characterized and compared to the groups defined by the cluster analysis. Axonal endings with round synaptic vesicles were labeled with more than 2 grains/micron2 which was about 30% of the radioactivity in the central nucleus of the IC. This was six to seven times greater than if the radioactivity had been randomly distributed. Other tissue compartments usually had less radioactivity. Some myelinated and unmyelinated axons were labeled, but, as a group they had lower amounts of radioactivity than predicted by random labeling. In most cases, only low levels of activity were found in glial and postsynaptic structures. Five groups of axonal endings in the medial part of the central nucleus were identified by an analysis which clustered similar types of endings. The variance of the longest axis, the mean diameter, the variance of area, and the mean area of the synaptic vesicles were the variables most useful in distinguishing these five groups. Axonal endings with round synaptic vesicles were classified as either small, or large, or very large, while endings with pleomorphic vesicles were either large or small. Using measurements of the cross-sectional diameter of dendritic microtubules, samples of digitized axonal endings from normal and experimental cases were normalized and

  5. Effect of monaural and binaural stimulation on cytoplasmic RNA content in cells of the central nucleus of the cat inferior colliculus.

    PubMed

    Shmigidina, G N

    1981-01-01

    A cytophotometric study of sections stained with gallocyanin and chrome alum showed that monaural stimulation for 2 h and binaural stimulation for 1.5 h with rhythmic noise signals led to a marked increase in the cytoplasmic RNA content per cell in the principal and large multipolar neurons of the dorsal and ventral parts of the ventrolateral region of the central nucleus of the inferior colliculus. The increase in cytoplasmic RNA content in the principal cells of the ipsi- and contralateral parts of this nucleus relative to the stimulated ear in the case of monaural stimulation and the increase in RNA content in response to binaural stimulation suggests a uniform distribution of bilaterally converging connections from the lower nuclei of the auditory system on the principal cells. The increase in cytoplasmic RNA in the large multipolar cells of the contralateral central nucleus in response to monaural stimulation is evidence of the predominantly contralateral projection to these cells. The results are evidence of convergence of binaural influences on the principal and large multipolar cells of the central nucleus of the inferior colliculus. PMID:6173796

  6. Intensity and frequency functions of [14C]2-deoxyglucose labelling in the central nucleus of the inferior colliculus in the cat.

    PubMed

    Brown, M; Webster, W R; Martin, R L

    1997-02-01

    The frequency organization of the central nucleus of the inferior colliculus (ICC) in the anesthetised cat was quantitatively mapped using [14C]2-deoxyglucose. From a standardised rostrocaudal region of the ICC, the position of peak selective labelling along the tonotopic axis closely conformed to the reported tonotopic organization of this nucleus. The position of the peak was found not to significantly change its position along the tonotopic axis with increasing stimulus intensity. However, the amplitude of peak uptake and width of selective labelling were shown to monotonically increase with increase in stimulus intensity. The increase in width of selective labelling, about the position of peak uptake, showed a slight asymmetry toward the high-frequency regions of the ICC. A 2-DG frequency-position function for the ICC, similar to that for the cochlea, enabled the width of 2-DG bands to be expressed in terms of their frequency spread along the tonotopic axis. This inturn enabled 2-DG tuning curves to be plotted which, when compared to electrophysiologically determined tuning curves, showed marked similarities. The minimum threshold and width (Q10) of these 2-DG tuning curves fell within the range reported for single units in the cat auditory pathway. PMID:9119768

  7. Projections of the cochlear nuclei and nucleus laminaris to the inferior colliculus of the barn owl.

    PubMed

    Takahashi, T T; Konishi, M

    1988-08-01

    The barn owl determines the directions from which sounds emanate by computing the interaural differences in the timing and intensity of sounds. These cues for sound localization are processed in independent channels originating at nucleus magnocellularis (NM) and nucleus angularis (NA), the cochlear nuclei. The cells of NM are specialized for encoding the phase of sounds in the ipsilateral ear. The cells of NA are specialized for encoding the intensity of sounds in the ipsilateral ear. NM projects solely, bilaterally, and tonotopically to nucleus laminaris (NL). NL and NA project to largely nonoverlapping zones in the central nucleus of the inferior colliculus (ICc), thus forming hodological subdivisions in which time and intensity information may be processed. The terminal field of NL occupies a discrete zone in the rostromedial portion of the contralateral ICc, which we have termed the "core" of ICc. The terminal field of NA surrounds the core of ICc and thus forms a "shell" around it. The projection from NL to the core conserves tonotopy. Low-frequency regions of NL project to the dorsal portions of the core whereas higher-frequency regions project to more ventral portions. This innervation pattern is consistent with earlier physiological studies of tonotopy. Physiological studies have also suggested that NL and the core of ICs contain a representation of the location of a sound source along the horizontal axis. Our data suggest that the projection from NL to the core preserves spatiotopy. Thus, the dorsal portion of NL on the left, which contains a representation of eccentric loci in the right hemifield, innervates the area of the right ICc core that represents eccentric right loci. The more ventral portion of the left NL, which represents loci close to the vertical meridian, innervates the more rostral portions of the right core, which also represents loci near the vertical meridian. PMID:2463286

  8. Preservation of spectrotemporal tuning between the nucleus laminaris and the inferior colliculus of the barn owl.

    PubMed

    Christianson, G Björn; Peña, José Luis

    2007-05-01

    Performing sound recognition is a task that requires an encoding of the time-varying spectral structure of the auditory stimulus. Similarly, computation of the interaural time difference (ITD) requires knowledge of the precise timing of the stimulus. Consistent with this, low-level nuclei of birds and mammals implicated in ITD processing encode the ongoing phase of a stimulus. However, the brain areas that follow the binaural convergence for the computation of ITD show a reduced capacity for phase locking. In addition, we have shown that in the barn owl there is a pooling of ITD-responsive neurons to improve the reliability of ITD coding. Here we demonstrate that despite two stages of convergence and an effective loss of phase information, the auditory system of the anesthetized barn owl displays a graceful transition to an envelope coding that preserves the spectrotemporal information throughout the ITD pathway to the neurons of the core of the central nucleus of the inferior colliculus. PMID:17314241

  9. Development of the projection from the nucleus of the brachium of the inferior colliculus to the superior colliculus in the ferret.

    PubMed

    Nodal, Fernando R; Doubell, Timothy P; Jiang, Ze D; Thompson, Ian D; King, Andrew J

    2005-05-01

    Neurons in the deeper layers of the superior colliculus (SC) have spatially tuned receptive fields that are arranged to form a map of auditory space. The spatial tuning of these neurons emerges gradually in an experience-dependent manner after the onset of hearing, but the relative contributions of peripheral and central factors in this process of maturation are unknown. We have studied the postnatal development of the projection to the ferret SC from the nucleus of the brachium of the inferior colliculus (nBIC), its main source of auditory input, to determine whether the emergence of auditory map topography can be attributed to anatomical rewiring of this projection. The pattern of retrograde labeling produced by injections of fluorescent microspheres in the SC on postnatal day (P) 0 and just after the age of hearing onset (P29), showed that the nBIC-SC projection is topographically organized in the rostrocaudal axis, along which sound azimuth is represented, from birth. Injections of biotinylated dextran amine-fluorescein into the nBIC at different ages (P30, 60, and 90) labeled axons with numerous terminals and en passant boutons throughout the deeper layers of the SC. This labeling covered the entire mediolateral extent of the SC, but, in keeping with the pattern of retrograde labeling following microsphere injections in the SC, was more restricted rostrocaudally. No systematic changes were observed with age. The stability of the nBIC-SC projection over this period suggests that developmental changes in auditory spatial tuning involve other processes, rather than a gross refinement of the projection from the nBIC. PMID:15791643

  10. Responses from two firing patterns in inferior colliculus neurons to stimulation of the lateral lemniscus dorsal nucleus.

    PubMed

    Li, Xiao-Ting; Wang, Ning-Yu; Wang, Yan-Jun; Xu, Zhi-Qing; Liu, Jin-Feng; Bai, Yun-Fei; Dai, Jin-Sheng; Zhao, Jing-Yi

    2016-05-01

    The γ-aminobutyric acid neurons (GABAergic neurons) in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this classification is associated with physiological function, the exact role for neurons with various firing patterns in acoustic processing remains poorly understood. In the present study, we analyzed characteristics of inferior colliculus neurons in vitro, and recorded responses to stimulation of the dorsal nucleus of the lateral lemniscus using the whole-cell patch clamp technique. Seven inferior colliculus neurons were tested and were classified into two firing patterns: sustained-regular (n = 4) and sustained-adapting firing patterns (n = 3). The majority of inferior colliculus neurons exhibited slight changes in response to stimulation and bicuculline. The responses of one neuron with a sustained-adapting firing pattern were suppressed after stimulation, but recovered to normal levels following application of the γ-aminobutyric acid receptor antagonist. One neuron with a sustained-regular pattern showed suppressed stimulation responses, which were not affected by bicuculline. Results suggest that GABAergic neurons in the inferior colliculus exhibit sustained-regular or sustained-adapting firing patterns. Additionally, GABAergic projections from the dorsal nucleus of the lateral lemniscus to the inferior colliculus are associated with sound localization. The different neuronal responses of various firing patterns suggest a role in sound localization. A better understanding of these mechanisms and functions will provide better clinical treatment paradigms for hearing deficiencies. PMID:27335563

  11. Responses from two firing patterns in inferior colliculus neurons to stimulation of the lateral lemniscus dorsal nucleus

    PubMed Central

    Li, Xiao-ting; Wang, Ning-yu; Wang, Yan-jun; Xu, Zhi-qing; Liu, Jin-feng; Bai, Yun-fei; Dai, Jin-sheng; Zhao, Jing-yi

    2016-01-01

    The γ-aminobutyric acid neurons (GABAergic neurons) in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this classification is associated with physiological function, the exact role for neurons with various firing patterns in acoustic processing remains poorly understood. In the present study, we analyzed characteristics of inferior colliculus neurons in vitro, and recorded responses to stimulation of the dorsal nucleus of the lateral lemniscus using the whole-cell patch clamp technique. Seven inferior colliculus neurons were tested and were classified into two firing patterns: sustained-regular (n = 4) and sustained-adapting firing patterns (n = 3). The majority of inferior colliculus neurons exhibited slight changes in response to stimulation and bicuculline. The responses of one neuron with a sustained-adapting firing pattern were suppressed after stimulation, but recovered to normal levels following application of the γ-aminobutyric acid receptor antagonist. One neuron with a sustained-regular pattern showed suppressed stimulation responses, which were not affected by bicuculline. Results suggest that GABAergic neurons in the inferior colliculus exhibit sustained-regular or sustained-adapting firing patterns. Additionally, GABAergic projections from the dorsal nucleus of the lateral lemniscus to the inferior colliculus are associated with sound localization. The different neuronal responses of various firing patterns suggest a role in sound localization. A better understanding of these mechanisms and functions will provide better clinical treatment paradigms for hearing deficiencies. PMID:27335563

  12. Enhanced visual responses in the superior colliculus and subthalamic nucleus in an animal model of Parkinson's disease.

    PubMed

    Rolland, M; Carcenac, C; Overton, P G; Savasta, M; Coizet, V

    2013-11-12

    Striatal dopaminergic denervation leads to a change in afferent activity within the basal ganglia. Coupled with the effect of local dopaminergic denervation in the subthalamic nucleus, this is likely to affect the responsiveness of subthalamic neurons to their hyperdirect inputs in Parkinson's disease. Therefore, in this report, we investigated subthalamic nucleus responses to visual stimuli relayed by one such input - the superior colliculus - in 6-hydroxydopamine (6-OHDA)-lesioned rats. We used a protocol where the superior colliculus was selectively unlocked from the inhibitory effect of anesthesia with an injection of bicuculline, attenuating GABAergic inhibition in the colliculus, which arises predominantly from the substantia nigra pars reticulata. We found that visual responses in the superior colliculus were facilitated by partial or total lesions of dopaminergic neurons in the substantia nigra pars compacta, once the colliculus was disinhibited by bicuculline. Responses were faster, larger in amplitude and lasted longer compared to those in control rats. In the subthalamic nucleus, visual responses were also increased in amplitude and magnitude in partial or total lesioned groups. A classic hypothesis in Parkinson's disease suggests that following dopaminergic denervation, the discharge of cells in the substantia nigra pars reticulata increases, thereby intensifying the inhibitory influence that this structure exerts on its targets in the thalamus and brainstem. Our results suggest that neuroadaptations may have taken place within the superior colliculus in order to maintain normal function in the face of increased inhibitory tone coming from the substantia nigra pars reticulata, which once reduced, gave rise to facilitated responding. This facilitated responding in the superior colliculus then appears to lead to facilitated responding in the subthalamic nucleus. PMID:23916713

  13. Color responses and their adaptation in human superior colliculus and lateral geniculate nucleus.

    PubMed

    Chang, Dorita H F; Hess, Robert F; Mullen, Kathy T

    2016-09-01

    We use an fMRI adaptation paradigm to explore the selectivity of human responses in the lateral geniculate nucleus (LGN) and superior colliculus (SC) to red-green color and achromatic contrast. We measured responses to red-green (RG) and achromatic (ACH) high contrast sinewave counter-phasing rings with and without adaptation, within a block design. The signal for the RG test stimulus was reduced following both RG and ACH adaptation, whereas the signal for the ACH test was unaffected by either adaptor. These results provide compelling evidence that the human LGN and SC have significant capacity for color adaptation. Since in the LGN red-green responses are mediated by P cells, these findings are in contrast to earlier neurophysiological data from non-human primates that have shown weak or no contrast adaptation in the P pathway. Cross-adaptation of the red-green color response by achromatic contrast suggests unselective response adaptation and points to a dual role for P cells in responding to both color and achromatic contrast. We further show that subcortical adaptation is not restricted to the geniculostriate system, but is also present in the superior colliculus (SC), an oculomotor region that until recently, has been thought to be color-blind. Our data show that the human SC not only responds to red-green color contrast, but like the LGN, shows reliable but unselective adaptation. PMID:27150230

  14. Dual 5-HT mechanisms in basolateral and central nuclei of amygdala in the regulation of the defensive behavior induced by electrical stimulation of the inferior colliculus.

    PubMed

    Macedo, Carlos Eduardo; Castilho, Vanessa Moreno; de Souza e Silva, Maria Angélica; Brandão, Marcus L

    2002-11-30

    Regulatory mechanisms in the basolateral nucleus of the amygdala (BLA) serves as a filter for unconditioned and conditioned aversive information that ascend to higher structures from the brainstem whereas the central nucleus (CeA) is the main output for the resultant defense reaction. We have shown that neural substrates in the inferior colliculus are activated by threatening stimuli of acoustic nature and have important functional links with the amygdala. In this work, we examined the influence of lesions with 5,7-dihydroxytryptamine (5,7-DHT) of these nuclei of amygdala on the aversive responses induced by electrical stimulation of the inferior colliculus. Thus, rats were implanted with an electrode in the CeA of the inferior colliculus for the determination of the thresholds of alertness, freezing and escape responses. Each rat also bore a cannula implanted in the BLA or CeA for injection of 5,7-DHT (8.0 microg/0.8 microl) or its vehicle. The data obtained show that CeA lesions increase the thresholds of aversive responses whereas BLA lesions decrease the thresholds of these responses. From this evidence it is suggested that defensive behavior induced by activation of the neural substrates of aversion in the inferior colliculus seems to depend on the integrity of the amygdala. BLA regulates the input and CeA functions as the output for these aversive states generated at brainstem level. It is likely that aversive information ascending from the inferior colliculus may receive either inhibitory or excitatory influences of 5-HT mechanisms in the BLA or CeA, respectively. PMID:12431748

  15. Topographical projection from the superior colliculus to the nucleus of the brachium of the inferior colliculus in the ferret: convergence of visual and auditory information.

    PubMed

    Doubell, T P; Baron, J; Skaliora, I; King, A J

    2000-12-01

    The normal maturation of the auditory space map in the deeper layers of the ferret superior colliculus (SC) depends on signals provided by the superficial visual layers, but it is unknown where or how these signals influence the developing auditory responses. Here we report that tracer injections in the superficial layers label axons with en passant and terminal boutons, both in the deeper layers of the SC and in their primary source of auditory input, the nucleus of the brachium of the inferior colliculus (nBIC). Electron microscopy confirmed that biocytin-labelled SC axons form axodendritic synapses on nBIC neurons. Injections of biotinylated dextran amine in the nBIC resulted in anterograde labelling in the deeper layers of the SC, as well as retrogradely labelled superficial and deep SC neurons, whose distribution varied systematically with the rostrocaudal placement of the injection sites in the nBIC. Topographical order in the projection from the SC to the ipsilateral nBIC was confirmed using fluorescent microspheres. We demonstrated the existence of functional SC-nBIC connections by making whole-cell current-clamp recordings from young ferret slices. Both monosynaptic and polysynaptic EPSPs were generated by electrical stimulation of either the superficial or deep SC layers. In addition to unimodal auditory units, both visual and bimodal visual-auditory units were recorded in the nBIC in vivo and their incidence was higher in juvenile ferrets than in adults. The SC-nBIC circuit provides a potential means by which visual and other sensory or premotor signals may be delivered to the nBIC to calibrate the representation of auditory space. PMID:11122340

  16. Shared and distinct retinal input to the mouse superior colliculus and dorsal lateral geniculate nucleus.

    PubMed

    Ellis, Erika M; Gauvain, Gregory; Sivyer, Benjamin; Murphy, Gabe J

    2016-08-01

    The mammalian retina conveys the vast majority of information about visual stimuli to two brain regions: the dorsal lateral geniculate nucleus (dLGN) and the superior colliculus (SC). The degree to which retinal ganglion cells (RGCs) send similar or distinct information to the two areas remains unclear despite the important constraints that different patterns of RGC input place on downstream visual processing. To resolve this ambiguity, we injected a glycoprotein-deficient rabies virus coding for the expression of a fluorescent protein into the dLGN or SC; rabies virus labeled a smaller fraction of RGCs than lipophilic dyes such as DiI but, crucially, did not label RGC axons of passage. Approximately 80% of the RGCs infected by rabies virus injected into the dLGN were colabeled with DiI injected into the SC, suggesting that many dLGN-projecting RGCs also project to the SC. However, functional characterization of RGCs revealed that the SC receives input from several classes of RGCs that largely avoid the dLGN, in particular RGCs in which 1) sustained changes in light intensity elicit transient changes in firing rate and/or 2) a small range of stimulus sizes or temporal fluctuations in light intensity elicit robust activity. Taken together, our results illustrate several unexpected asymmetries in the information that the mouse retina conveys to two major downstream targets and suggest that differences in the output of dLGN and SC neurons reflect, at least in part, differences in the functional properties of RGCs that innervate the SC but not the dLGN. PMID:27169509

  17. Shared and distinct retinal input to the mouse superior colliculus and dorsal lateral geniculate nucleus

    PubMed Central

    Ellis, Erika M.; Gauvain, Gregory; Sivyer, Benjamin

    2016-01-01

    The mammalian retina conveys the vast majority of information about visual stimuli to two brain regions: the dorsal lateral geniculate nucleus (dLGN) and the superior colliculus (SC). The degree to which retinal ganglion cells (RGCs) send similar or distinct information to the two areas remains unclear despite the important constraints that different patterns of RGC input place on downstream visual processing. To resolve this ambiguity, we injected a glycoprotein-deficient rabies virus coding for the expression of a fluorescent protein into the dLGN or SC; rabies virus labeled a smaller fraction of RGCs than lipophilic dyes such as DiI but, crucially, did not label RGC axons of passage. Approximately 80% of the RGCs infected by rabies virus injected into the dLGN were colabeled with DiI injected into the SC, suggesting that many dLGN-projecting RGCs also project to the SC. However, functional characterization of RGCs revealed that the SC receives input from several classes of RGCs that largely avoid the dLGN, in particular RGCs in which 1) sustained changes in light intensity elicit transient changes in firing rate and/or 2) a small range of stimulus sizes or temporal fluctuations in light intensity elicit robust activity. Taken together, our results illustrate several unexpected asymmetries in the information that the mouse retina conveys to two major downstream targets and suggest that differences in the output of dLGN and SC neurons reflect, at least in part, differences in the functional properties of RGCs that innervate the SC but not the dLGN. PMID:27169509

  18. Descending projections from auditory cortex to excitatory and inhibitory cells in the nucleus of the brachium of the inferior colliculus

    PubMed Central

    Mellott, Jeffrey G.; Bickford, Martha E.; Schofield, Brett R.

    2014-01-01

    Descending projections from the auditory cortex (AC) terminate in subcortical auditory centers from the medial geniculate nucleus (MG) to the cochlear nucleus, allowing the AC to modulate the processing of acoustic information at many levels of the auditory system. The nucleus of the brachium of the inferior colliculus (NBIC) is a large midbrain auditory nucleus that is a target of these descending cortical projections. The NBIC is a source of several auditory projections, including an ascending projection to the MG. This ascending projection appears to originate from both excitatory and inhibitory NBIC cells, but whether the cortical projections contact either of these cell groups is unknown. In this study, we first combined retrograde tracing and immunochemistry for glutamic acid decarboxylase (GAD, a marker of GABAergic cells) to identify GABAergic and non-GABAergic NBIC projections to the MG. Our first result is that GAD-immunopositive cells constitute ~17% of the NBIC to MG projection. We then used anterograde labeling and electron microscopy to examine the AC projection to the NBIC. Our second result is that cortical boutons in the NBIC form synapses with round vesicles and asymmetric synapses, consistent with excitatory effects. Finally, we combined fluorescent anterograde labeling of corticofugal axons with immunochemistry and retrograde labeling of NBIC cells that project to the MG. These final results suggest first that AC axons contact both GAD-negative and GAD-positive NBIC cells and, second, that some of cortically-contacted cells project to the MG. Overall, the results imply that corticofugal projections can modulate both excitatory and inhibitory ascending projections from the NBIC to the auditory thalamus. PMID:25339870

  19. Wisteria Floribunda Agglutinin-Labeled Perineuronal Nets in the Mouse Inferior Colliculus, Thalamic Reticular Nucleus and Auditory Cortex.

    PubMed

    Fader, Sarah M; Imaizumi, Kazuo; Yanagawa, Yuchio; Lee, Charles C

    2016-01-01

    Perineuronal nets (PNNs) are specialized extracellular matrix molecules that are associated with the closing of the critical period, among other functions. In the adult brain, PNNs surround specific types of neurons, however the expression of PNNs in the auditory system of the mouse, particularly at the level of the midbrain and forebrain, has not been fully described. In addition, the association of PNNs with excitatory and inhibitory cell types in these structures remains unknown. Therefore, we sought to investigate the expression of PNNs in the inferior colliculus (IC), thalamic reticular nucleus (TRN) and primary auditory cortex (A1) of the mouse brain by labeling with wisteria floribunda agglutinin (WFA). To aid in the identification of inhibitory neurons in these structures, we employed the vesicular GABA transporter (VGAT)-Venus transgenic mouse strain, which robustly expresses an enhanced yellow-fluorescent protein (Venus) natively in nearly all gamma-amino butyric acid (GABA)-ergic inhibitory neurons, thus enabling a rapid and unambiguous assessment of inhibitory neurons throughout the nervous system. Our results demonstrate that PNNs are expressed throughout the auditory midbrain and forebrain, but vary in their local distribution. PNNs are most dense in the TRN and least dense in A1. Furthermore, PNNs are preferentially associated with inhibitory neurons in A1 and the TRN, but not in the IC of the mouse. These data suggest regionally specific roles for PNNs in auditory information processing. PMID:27089371

  20. Neuronal relationships between the dorsal periaqueductal nucleus and the inferior colliculus (nucleus commissuralis) in the cat. A Golgi study.

    PubMed Central

    Herrera, M; Sánchez del Campo, F; Ruiz, A; Smith Agreda, V

    1988-01-01

    Cell types in the dorsal periaqueductal nucleus (PAGd) were studied with the aid of the rapid Golgi method in young cats. The neurons were subdivided into fusiform and stellate types with several varieties of the latter class according to the final destination of their axons. Fusiform neurons send their axons to the neuropil of the Ncom. In turn these neurons receive descending fibres from the nucleus commissuralis (Ncom) which seem to establish axo-dendritic contacts. Also commissural neurons receive contacts from ascending fibres of the PAGd. On the basis of Golgi material it is concluded that particular neuronal types of the PAGd could establish reciprocal connections with neuronal elements of the ventral part of the Ncom. The present study supports the hypothesis that the PAGd could be subdivided into discrete cell groups according to their afferent and efferent projections. Images Fig. 1 Fig. 2 Fig. 4 PMID:3225218

  1. BOLD responses in the superior colliculus and lateral geniculate nucleus of the rat viewing an apparent motion stimulus.

    PubMed

    Lau, Condon; Zhang, Jevin W; Xing, Kyle K; Zhou, Iris Y; Cheung, Matthew M; Chan, Kevin C; Wu, Ed X

    2011-10-01

    In rats, the superior colliculus (SC) is a main destination for retinal ganglion cells and is an important subcortical structure for vision. Electrophysiology studies have observed that many SC neurons are highly sensitive to moving objects, but complementary non-invasive functional imaging studies with larger fields of view have been rarely conducted. In this study, BOLD fMRI is used to measure the SC and nearby lateral geniculate nucleus' (LGN) hemodynamic responses, in normal adult Sprague Dawley (SD) rats, during a dynamic visual stimulus similar to those used in long-range apparent motion studies. The stimulation paradigm consists of four light spots arranged in a linear array and turned on and off sequentially at different rates to create five effective speeds of motion (7, 14, 41, 82, and 164°/s across the visual field). Stationary periods (same light spot always on) are interleaved between the moving periods. The speed response function (SRF), the hemodynamic response amplitude at each speed tested, is measured. Significant responses are observed in the SC and LGN at all speeds. In the SC, the SRF increases monotonically from 7 to 82°/s. The minimum response amplitude occurs at 164°/s. The results suggest that the SC is sensitive to slow moving visual stimuli but the hemodynamic response is reduced at higher speeds. In the LGN, the SRF exhibits a similar trend to that of the SC, but response amplitude during 7°/s stimulation is comparable to that during 164°/s stimulation. These findings are in good agreement with previous electrophysiology studies conducted on albino rats like the SD strain. This work represents the first fMRI study of stimulus speed dependence in the SC and is also the first fMRI study of motion responsiveness in the rat. PMID:21741483

  2. Noise-induced hyperactivity in the inferior colliculus: its relationship with hyperactivity in the dorsal cochlear nucleus

    PubMed Central

    Manzoor, N. F.; Licari, F. G.; Klapchar, M.; Elkin, R. L.; Gao, Y.; Chen, G.

    2012-01-01

    Intense noise exposure causes hyperactivity to develop in the mammalian dorsal cochlear nucleus (DCN) and inferior colliculus (IC). It has not yet been established whether the IC hyperactivity is driven by hyperactivity from extrinsic sources that include the DCN or instead is maintained independently of this input. We have investigated the extent to which IC hyperactivity is dependent on input from the contralateral DCN by comparing recordings of spontaneous activity in the IC of noise-exposed and control hamsters before and after ablation of the contralateral DCN. One group of animals was binaurally exposed to intense sound (10 kHz, 115 dB SPL, 4 h), whereas the control group was not. Both groups were studied electrophysiologically 2–3 wk later by first mapping spontaneous activity along the tonotopic axis of the IC to confirm induction of hyperactivity. Spontaneous activity was then recorded at a hyperactive IC locus over two 30-min periods, one with DCNs intact and the other after ablation of the contralateral DCN. In a subset of animals, activity was again mapped along the tonotopic axis after the time course of the activity was recorded before and after DCN ablation. Following recordings, the brains were fixed, and histological evaluations were performed to assess the extent of DCN ablation. Ablation of the DCN resulted in major reductions of IC hyperactivity. Levels of postablation activity in exposed animals were similar to the levels of activity in the IC of control animals, indicating an almost complete loss of hyperactivity in exposed animals. The results suggest that hyperactivity in the IC is dependent on support from extrinsic sources that include and may even begin with the DCN. This finding does not rule out longer term compensatory or homeostatic adjustments that might restore hyperactivity in the IC over time. PMID:22552192

  3. The Distinct Role of the Amygdala, Superior Colliculus and Pulvinar in Processing of Central and Peripheral Snakes

    PubMed Central

    Almeida, Inês; Soares, Sandra C.; Castelo-Branco, Miguel

    2015-01-01

    Introduction Visual processing of ecologically relevant stimuli involves a central bias for stimuli demanding detailed processing (e.g., faces), whereas peripheral object processing is based on coarse identification. Fast detection of animal shapes holding a significant phylogenetic value, such as snakes, may benefit from peripheral vision. The amygdala together with the pulvinar and the superior colliculus are implicated in an ongoing debate regarding their role in automatic and deliberate spatial processing of threat signals. Methods Here we tested twenty healthy participants in an fMRI task, and investigated the role of spatial demands (the main effect of central vs. peripheral vision) in the processing of fear-relevant ecological features. We controlled for stimulus dependence using true or false snakes; snake shapes or snake faces and for task constraints (implicit or explicit). The main idea justifying this double task is that amygdala and superior colliculus are involved in both automatic and controlled processes. Moreover the explicit/implicit instruction in the task with respect to emotion is not necessarily equivalent to explicit vs. implicit in the sense of endogenous vs. exogenous attention, or controlled vs. automatic processes. Results We found that stimulus-driven processing led to increased amygdala responses specifically to true snake shapes presented in the centre or in the peripheral left hemifield (right hemisphere). Importantly, the superior colliculus showed significantly biased and explicit central responses to snake-related stimuli. Moreover, the pulvinar, which also contains foveal representations, also showed strong central responses, extending the results of a recent single cell pulvinar study in monkeys. Similar hemispheric specialization was found across structures: increased amygdala responses occurred to true snake shapes presented to the right hemisphere, with this pattern being closely followed by the superior colliculus and the

  4. Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate

    NASA Astrophysics Data System (ADS)

    McCreery, Douglas; Han, Martin; Pikov, Victor; Yadav, Kamal; Pannu, Satinderpall

    2013-10-01

    Objectives. Persons without a functional auditory nerve cannot benefit from cochlear implants, but some hearing can be restored by an auditory brainstem implant (ABI) with stimulating electrodes implanted on the surface of the cochlear nucleus (CN). Most users benefit from their ABI, but speech recognition tends to be poorer than for users of cochlear implants. Psychophysical studies suggest that poor modulation detection may contribute to the limited performance of ABI users. In a cat model, we determined how the pulse rate of the electrical stimulus applied within or on the CN affects temporal and rate encoding of amplitude modulation (AM) by neurons in the central nucleus of the inferior colliculus (ICC). Approach. Stimulating microelectrodes were implanted chronically in and on the cats' CN, and multi-site recording microelectrodes were implanted chronically into the ICC. Encoding of AM pulse trains by neurons in the ICC was characterized as vector strength (VS), the synchrony of neural activity with the AM, and as the mean rate of neuronal action potentials (neuronal spike rate (NSR)). Main results. For intranuclear microstimulation, encoding of AM as VS was up to 3 dB greater when stimulus pulse rate was increased from 250 to 500 pps, but only for neuronal units with low best acoustic frequencies, and when the electrical stimulation was modulated at low frequencies (10-20 Hz). For stimulation on the surface of the CN, VS was similar at 250 and 500 pps, and the dynamic range of the VS was reduced for pulse rates greater than 250 pps. Modulation depth was encoded strongly as VS when the maximum stimulus amplitude was held constant across a range of modulation depth. This ‘constant maximum’ protocol allows enhancement of modulation depth while preserving overall dynamic range. However, modulation depth was not encoded as strongly as NSR. Significance. The findings have implications for improved sound processors for present and future ABIs. The performance of

  5. The smooth monostratified ganglion cell: evidence for spatial diversity in the Y-cell pathway to the lateral geniculate nucleus and superior colliculus in the macaque monkey.

    PubMed

    Crook, Joanna D; Peterson, Beth B; Packer, Orin S; Robinson, Farrel R; Gamlin, Paul D; Troy, John B; Dacey, Dennis M

    2008-11-26

    In the primate visual system approximately 20 morphologically distinct pathways originate from retinal ganglion cells and project in parallel to the lateral geniculate nucleus (LGN) and/or the superior colliculus. Understanding of the properties of these pathways and the significance of such extreme early pathway diversity for later visual processing is limited. In a companion study we found that the magnocellular LGN-projecting parasol ganglion cells also projected to the superior colliculus and showed Y-cell receptive field structure supporting the hypothesis that the parasol cells are analogous to the well studied alpha-Y cell of the cat's retina. We here identify a novel ganglion cell class, the smooth monostratified cells, that share many properties with the parasol cells. Smooth cells were retrogradely stained from tracer injections made into either the LGN or superior colliculus and formed inner-ON and outer-OFF populations with narrowly monostratified dendritic trees that surprisingly appeared to perfectly costratify with the dendrites of parasol cells. Also like parasol cells, smooth cells summed input from L- and M-cones, lacked measurable S-cone input, showed high spike discharge rates, high contrast and temporal sensitivity, and a Y-cell type nonlinear spatial summation. Smooth cells were distinguished from parasol cells however by smaller cell body and axon diameters but approximately 2 times larger dendritic tree and receptive field diameters that formed a regular but lower density mosaic organization. We suggest that the smooth and parasol populations may sample a common presynaptic circuitry but give rise to distinct, parallel achromatic spatial channels in the primate retinogeniculate pathway. PMID:19036959

  6. Evidence for a role of the parafascicular nucleus of the thalamus in the control of epileptic seizures by the superior colliculus

    PubMed Central

    Nail-Boucherie, Karine; Lê-Pham, Bich-Thuy; Gobaille, Serge; Maitre, Michel; Aunis, Dominique; Depaulis, Antoine

    2005-01-01

    Purpose The aim of this study was to investigate whether the nucleus parafascicularis (Pf) of the thalamus could be a relay of the control of epileptic seizures by the superior colliculus (SC). The Pf is one of the main ascending projection of the SC, the disinhibition of which has been shown to suppress seizures in different animal models and has been proposed as the main relay of the nigral control of epilepsy. Methods Rats with genetic absence seizures (Generalized Absence Epilepsy Rat from Strasbourg or GAERS) were used in this study. The effect of bilateral microinjection of picrotoxin, a GABA antagonist, in the SC on the glutamate and GABA extracellular concentration within the Pf was first investigated using microdialysis. In a second experiment, the effect of direct activation of Pf neurons on the occurrence of absence seizures was examined by microinjection of low doses of kainate, a glutamate agonist. Results Bilateral injection of picrotoxin (33 pmol/side) in the SC suppressed spike and wave discharges for 20 min. This treatment resulted in an increase of glutamate but not GABA levels in the Pf during the same time course. Bilateral injection of kainate (35 pmol/side) into the Pf significantly suppressed spike and wave discharges for 20 min, whereas such injection were without effects when at least one the site was located outside the Pf. Conclusions These data suggest that glutamatergic projections to the Pf could be involved in the control of seizures by the SC. Disinhibition of these neurons could lead to seizure suppression and may be involved in the nigral control of epilepsy. PMID:15660780

  7. Optogenetic stimulation of the cochlear nucleus using channelrhodopsin-2 evokes activity in the central auditory pathways.

    PubMed

    Darrow, Keith N; Slama, Michaël C C; Kozin, Elliott D; Owoc, Maryanna; Hancock, Kenneth; Kempfle, Judith; Edge, Albert; Lacour, Stephanie; Boyden, Edward; Polley, Daniel; Brown, M Christian; Lee, Daniel J

    2015-03-01

    Optogenetics has become an important research tool and is being considered as the basis for several neural prostheses. However, few studies have applied optogenetics to the auditory brainstem. This study explored whether optical activation of the cochlear nucleus (CN) elicited responses in neurons in higher centers of the auditory pathway and whether it elicited an evoked response. Viral-mediated gene transfer was used to express channelrhodopsin-2 (ChR2) in the mouse CN. Blue light was delivered via an optical fiber placed near the surface of the infected CN and recordings were made in higher-level centers. Optical stimulation evoked excitatory multiunit spiking activity throughout the tonotopic axis of the central nucleus of the inferior colliculus (IC) and the auditory cortex (Actx). The pattern and magnitude of IC activity elicited by optical stimulation was comparable to that obtained with a 50dB SPL acoustic click. This broad pattern of activity was consistent with histological confirmation of green fluorescent protein (GFP) label of cell bodies and axons throughout the CN. Increasing pulse rates up to 320Hz did not significantly affect threshold or bandwidth of the IC responses, but rates higher than 50Hz resulted in desynchronized activity. Optical stimulation also evoked an auditory brainstem response, which had a simpler waveform than the response to acoustic stimulation. Control cases showed no responses to optical stimulation. These data suggest that optogenetic control of central auditory neurons is feasible, but opsins with faster channel kinetics may be necessary to convey information at rates typical of many auditory signals. PMID:25481416

  8. Optogenetic stimulation of the cochlear nucleus using channelrhodopsin-2 evokes activity in the central auditory pathway

    PubMed Central

    Darrow, Keith N.; Slama, Michaël C. C.; Owoc, Maryanna; Kozin, Elliott; Hancock, Kenneth; Kempfle, Judith; Edge, Albert; Lacour, Stephanie; Boyden, Edward; Polley, Daniel; Brown, M. Christian; Lee, Daniel J.

    2016-01-01

    Optogenetics has become an important research tool and is being considered as the basis for several neural prostheses. However, few studies have applied optogenetics to the auditory brainstem. This study explored whether optical activation of the cochlear nucleus (CN) elicited responses in neurons in higher centers of the auditory pathway, and it measured the evoked response to optical stimulation. Viral-mediated gene transfer was used to express channelrhodopsin-2 (ChR2) in the mouse CN. Blue light was delivered via an optical fiber placed near the surface of the infected CN and recordings were made in higher-level centers. Optical stimulation evoked excitatory multiunit spiking activity throughout the tonotopic axis of central nucleus of the inferior colliculus (IC) and the auditory cortex (Actx). The pattern and magnitude of IC activity elicited by optical stimulation was comparable to that obtained with a 50 dB SPL acoustic click stimulus. This broad pattern of activity was consistent with histological confirmation of GFP label of cell bodies and axons throughout the CN. Increasing pulse rates up to 320 Hz did not significantly affect threshold or bandwidth of the IC responses, but rates higher than 50 Hz resulted in desynchronized activity. Optical stimulation also evoked an auditory brainstem response, which had a simpler waveform than the response to acoustic stimulation. Control cases showed no responses to optical stimulation. These data suggest that optogenetic control of central auditory neurons is feasible, but opsins with faster channel kinetics will be necessary to convey information in rates typical of many auditory signals. PMID:25481416

  9. Combination-sensitive neurons in the inferior colliculus.

    PubMed

    Mittmann, D H; Wenstrup, J J

    1995-10-01

    We examined whether neurons in the inferior colliculus of the mustached bat (Pteronotus parnellii) are combination sensitive, responding to both low- and high-frequency components of the bat's sonar signal. These neurons, previously reported in the thalamus and cortex, analyze sonar target features including distance. Of 82 single units and 36 multiple units from the 58-112 kHz representations of the inferior colliculus, most (86%) displayed sensitivity to low-frequency sounds that was tuned in the range of the fundamental biosonar component (24-31 kHz). All histologically localized units were in the central nucleus of the inferior colliculus (ICC). There were two major types of combination-sensitive influences. Many neurons were facilitated by low-frequency sounds and selective for particular delays between the low- and high-frequency components. In other neurons, the low-frequency signal was inhibitory if presented simultaneously or a few milliseconds prior to the high-frequency signal. The results indicate that mechanisms creating specialized frequency comparisons and delay sensitivity in combination-sensitive neurons operate at the ICC or below. Since combination sensitivity or multipeaked tuning curves occur in the auditory systems of many species, ICC neurons in these animals may also respond to species-specific frequency combinations. PMID:8974996

  10. Collateral projections from the lateral parabrachial nucleus to the paraventricular thalamic nucleus and the central amygdaloid nucleus in the rat.

    PubMed

    Liang, Shao-Hua; Yin, Jun-Bin; Sun, Yi; Bai, Yang; Zhou, Kai-Xiang; Zhao, Wen-Jun; Wang, Wei; Dong, Yu-Lin; Li, Yun-Qing

    2016-08-26

    Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals. PMID:27423318

  11. Mammal-Like Organization of the Avian Midbrain Central Gray and a Reappraisal of the Intercollicular Nucleus

    PubMed Central

    Kingsbury, Marcy A.; Kelly, Aubrey M.; Schrock, Sara E.; Goodson, James L.

    2011-01-01

    In mammals, rostrocaudal columns of the midbrain periaqueductal gray (PAG) regulate diverse behavioral and physiological functions, including sexual and fight-or-flight behavior, but homologous columns have not been identified in non-mammalian species. In contrast to mammals, in which the PAG lies ventral to the superior colliculus and surrounds the cerebral aqueduct, birds exhibit a hypertrophied tectum that is displaced laterally, and thus the midbrain central gray (CG) extends mediolaterally rather than dorsoventrally as in mammals. We therefore hypothesized that the avian CG is organized much like a folded open PAG. To address this hypothesis, we conducted immunohistochemical comparisons of the midbrains of mice and finches, as well as Fos studies of aggressive dominance, subordinance, non-social defense and sexual behavior in territorial and gregarious finch species. We obtained excellent support for our predictions based on the folded open model of the PAG and further showed that birds possess functional and anatomical zones that form longitudinal columns similar to those in mammals. However, distinguishing characteristics of the dorsal/dorsolateral PAG, such as a dense peptidergic innervation, a longitudinal column of neuronal nitric oxide synthase neurons, and aggression-induced Fos responses, do not lie within the classical avian CG, but in the laterally adjacent intercollicular nucleus (ICo), suggesting that much of the ICo is homologous to the dorsal PAG. PMID:21694758

  12. Neuronal morphology in subdivisions of the inferior colliculus of chicken (Gallus gallus).

    PubMed

    Niederleitner, Bertram; Luksch, Harald

    2012-05-01

    The avian inferior colliculus (IC), also referred to as the nucleus mesencephalicus lateralis pars dorsalis (MLd), is an auditory midbrain nucleus that converges auditory cues from tonotopically organized brainstem nuclei. This information is relayed onto the optic tectum on the one hand and to nucleus ovoidalis on the other hand. Morphologically, there has been considerable debate about the number and nomenclature of the subnuclei within the IC. Here, we provide morphological characteristics of single cells in five IC subnuclei in chicken. The cellular structure within the IC was studied by whole-cell patch technique and biocytin iontophoresis. In addition, histological staining was performed, to delineate the borders between subnuclei of the IC. We were able to discriminate between 5 subnuclei: the core of the central nucleus (ICCc), the medial and lateral shell of the central nucleus (ICCms and ICCls), the external nucleus (ICX) and the superficial nucleus (ICS) of the IC. Our findings suggest the existence of at least two different morphologies of neurons with two subtypes each. The IC in chicken is a largely homogenous nucleus in terms of neuronal anatomy on a cellular level. However, its compartmentation into diversified subnuclei with different neurophysiological characteristics suggests a complex system to process auditory information. The auditory system in chicken is not as hypertrophied as in specialists such as the barn owl, but appears to have comparable connectivity and cellular morphology. PMID:22525356

  13. The Double Nucleus and Central Black Hole of M31

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Bender, Ralf

    1999-09-01

    New spectroscopy of M31 supports Tremaine's model in which both nuclei are parts of a single eccentric disk of stars orbiting the black hole (BH). The kinematics and Hubble Space Telescope photometry are used to measure the offset of the BH from the center of mass. This confirms that the BH mass is ~3×107 Msolar by a technique that is nearly independent of stellar-dynamical models. We present spectroscopy of the nucleus of M31 obtained with the Canada-France-Hawaii Telescope and Subarcsecond Imaging Spectrograph. Spectra at the Ca infrared triplet lines (seeing σ*=0.27") are used to measure the stellar kinematics, and spectra at the Mg I b lines (σ*=0.31") are used to measure metallicities. We also measure nonparametric line-of-sight velocity distributions (LOSVDs). All spectra confirm the steep rotation and velocity dispersion gradients that imply that M31 contains a 3.3×107 Msolar central dark object. At σ*=0.27", the maximum bulge-subtracted rotation velocity of the nucleus is 233+/-4 km s-1 on the P2 side, and the maximum velocity dispersion is 287+/-9 km s-1. The dispersion peak is displaced by 0.20"+/-0.03" from the velocity center in the direction opposite to P1, confirming a result by Bacon and coworkers. The higher surface brightness nucleus, P1, is colder than the bulge, with σ~=100 km s-1 at r~=1''. Cold light from P1 contributes at the velocity center; this explains part of the σ(r) asymmetry. The nucleus is cold at r>~1'' on both sides of the center. Our results are used to test Tremaine's model in which the double nucleus is a single eccentric disk of stars orbiting the BH. (1) The model predicts that the velocity center of the nucleus is displaced by 0.2" from P2 toward P1. Our observations show a displacement of 0.08"+/-0.01" before bulge subtraction and 0.10"+/-0.01" after bulge subtraction. (2) The model predicts a minimum σ~=135 km s-1 at P1. We observe σ=123+/-2 km s-1. Observations (1) and (2) may be reconciled with the model if its

  14. Consolidation of altered associability information by amygdala central nucleus.

    PubMed

    Schiffino, Felipe L; Holland, Peter C

    2016-09-01

    The surprising omission of a reinforcer can enhance the associability of the stimuli that were present when the reward prediction error was induced, so that they more readily enter into new associations in the future. Previous research from this laboratory identified brain circuit elements critical to the enhancement of stimulus associability by the omission of an expected event and to the subsequent expression of that altered associability in more rapid learning. These elements include the amygdala, the midbrain substantia nigra, the basal forebrain substantia innominata, the dorsolateral striatum, the secondary visual cortex, and the posterior parietal cortex. Here, we found that consolidation of a surprise-enhanced associability memory in a serial prediction task depends on processing in the amygdala central nucleus (CeA) after completion of sessions that included the surprising omission of an expected event. Post-surprise infusions of anisomycin, lidocaine, or muscimol prevented subsequent display of surprise-enhanced associability. Because previous studies indicated that CeA function is unnecessary for the expression of associability enhancements that were induced previously when CeA function was intact (Holland & Gallagher, 2006), we interpreted these results as indicating that post-surprise activity of CeA ("surprise replay") is necessary for the consolidation of altered associability memories elsewhere in the brain, such as the posterior parietal cortex (Schiffino et al., 2014a). PMID:27427328

  15. Adaptive adjustment of connectivity in the inferior colliculus revealed by focal pharmacological inactivation.

    PubMed

    Gold, J I; Knudsen, E I

    2001-04-01

    In the midbrain sound localization pathway of the barn owl, a map of auditory space is synthesized in the external nucleus of the inferior colliculus (ICX) and transmitted to the optic tectum. Early auditory experience shapes these maps of auditory space in part by modifying the tuning of the constituent neurons for interaural time difference (ITD), a primary cue for sound-source azimuth. Here we show that these adaptive modifications in ITD tuning correspond to changes in the pattern of connectivity within the inferior colliculus. We raised owls with an acoustic filtering device in one ear that caused frequency-dependent changes in sound timing and level. As reported previously, device rearing shifted the representation of ITD in the ICX and tectum but not in the primary source of input to the ICX, the central nucleus of the inferior colliculus (ICC). We applied the local anesthetic lidocaine (QX-314) iontophoretically in the ICC to inactivate small populations of neurons that represented particular values of frequency and ITD. We measured the effect of this inactivation in the optic tecta of a normal owl and owls raised with the device. In the normal owl, inactivation at a critical site in the ICC eliminated responses in the tectum to the frequency-specific ITD value represented at the site of inactivation in the ICC. The location of this site was consistent with the known pattern of ICC-ICX-tectum connectivity. In the device-reared owls, adaptive changes in the representation of ITD in the tectum corresponded to dramatic and predictable changes in the locations of the critical sites of inactivation in the ICC. Given that the abnormal representation of ITD in the tectum depended on frequency and was likely conveyed directly from the ICX, these results suggest that experience causes large-scale, frequency-specific adjustments in the pattern of connectivity between the ICC and the ICX. PMID:11287481

  16. Serotonergic modulation of inhibitory synaptic transmission in mouse inferior colliculus.

    PubMed

    Obara, Nobuyuki; Kamiya, Haruyuki; Fukuda, Satoshi

    2014-01-01

    The inferior colliculus (IC) transmits the ascending auditory signal to the thalamic medial geniculate nucleus. Previous studies have reported that serotonergic input originating from the raphe nuclei has a strong influence on signal processing within the central nucleus of the IC. To identify the cellular target for the serotonergic modulation in the IC, we examined the effect of serotonin as well as selective serotonin reuptake inhibitor (SSRI) fluvoxamine on spontaneous GABAergic and glycinergic inhibitory postsynaptic currents (sIPSCs) recorded with whole-cell recordings.Consistent with earlier studies, we confirmed that serotonin robustly enhanced the frequency, but not amplitude, of GABAergic sIPSCs. It should be noted that the application of fluvoxamine alone marginally increased the frequency of GABAergic sIPSCs. These findings suggest that serotonin is endogenously released even in slice preparations, and it negatively modulates the tone of activity of inhibitory neurons within IC. We also examined the effect of serotonin and fluvoxamine on glycinergic sIPSCs and found that serotonin has a significantly weaker effect on glycinergic sIPSCs than on GABAergic sIPSCs. The differential sensitivity of the GABAergic and glycinergic sIPSCs to serotonin implies that serotonergic input plays a specific role in auditory information processing.Moreover, it suggests that the serotonergic input may contribute to pathological conditions such as tinnitus. PMID:24573204

  17. Central Pupillary Light Reflex Circuits in the Cat: I. The Olivary Pretectal Nucleus

    PubMed Central

    Sun, Wensi; May, Paul J.

    2014-01-01

    The central pathways subserving the feline pupillary light reflex were examined by defining retinal input to the olivary pretectal nucleus (OPt), the midbrain projections of this nucleus, and the premotor neurons within it. Unilateral intravitreal wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) injections revealed differences in the pattern of retinal OPt termination on the two sides. Injections of WGA-HRP into OPt labeled terminals bilaterally in the anteromedian nucleus, and to a lesser extent in the supraoculomotor area, centrally projecting Edinger-Westphal nucleus and nucleus of the posterior commissure. Labeled terminals, as well as retrogradely labeled multipolar cells, were present in the contralateral OPt, indicating a commissural pathway. Injections of WGA-HRP into the anteromedian nucleus labeled fusiform premotor neurons within the OPt, as well as multipolar cells in the nucleus of the posterior commissure. Connections between retinal terminals and the pretectal premotor neurons were characterized by combining vitreous chamber and anteromedian nucleus injections of WGA-HRP in the same animal. Fusiform shaped, retrogradely labeled cells fell within the anterogradely labeled retinal terminal field in OPt. Ultrastructural analysis revealed labeled retinal terminals containing clear spherical vesicles. They contacted labeled pretectal premotor neurons via asymmetric synaptic densities. These results provide an anatomical substrate for the pupillary light reflex in the cat. Pretectal premotor neurons receive direct retinal input via synapses suggestive of an excitatory drive, and project directly to nuclei containing preganglionic motoneurons. These projections are concentrated in the anteromedian nucleus, indicating its involvement in the pupillary light reflex. PMID:24706328

  18. Neuroanatomical and neuropharmacological study of opioid pathways in the mesencephalic tectum: effect of mu(1)- and kappa-opioid receptor blockade on escape behavior induced by electrical stimulation of the inferior colliculus.

    PubMed

    Osaki, M Y; Castellan-Baldan, L; Calvo, F; Carvalho, A D; Felippotti, T T; de Oliveira, R; Ubiali, W A; Paschoalin-Maurin, T; Elias-Filho, D H; Motta, V; da Silva, L A; Coimbra, N C

    2003-12-01

    Deep layers of the superior colliculus (DLSC), the dorsal and ventral periaqueductal gray matter (PAG), and inferior colliculus (IC) are midbrain structures involved in the generation of defensive behavior. beta-Endorphin and Leu-enkephalin are some neurotransmitters that may modulate such behavior in mammals. Light microscopy immunocytochemistry with streptavidin method was used for the localization of the putative cells of defensive behavior with antibodies for endogenous opioids in rat brainstem. Midbrain structures showed positive neurons to beta-endorphin and Leu-enkephalin in similar distributions in the experimental animals, but we also noted the presence of varicose fibers positive to endogenous opioids in the PAG. Neuroanatomical techniques showed varicose fibers from the central nucleus of the inferior colliculus to ventral aspects of the PAG, at more caudal levels. Naloxonazine and nor-binaltorphimine, competitive antagonists that block mu(1)- and kappa-opioid receptors, were then used in the present work to investigate the involvement of opioid peptide neural system in the control of the fear-induced reactions evoked by electrical stimulation of the neural substrates of the inferior colliculus. The fear-like responses were measured by electrical stimulation of the central nucleus of the inferior colliculus, eliciting the escape behavior, which is characterized by vigorous running and jumping. Central administration of opioid antagonists (2.5 microg/0.2 microl and 5.0 microg/0.2 microl) was performed in non-anesthetized animals (Rattus norvegicus), and the behavioral manifestations of fear were registered after 10 min, 2 h, and 24 h of the pretreatment. Naloxonazine caused an increase of the defensive threshold, as compared to control, suggesting an antiaversive effect of the antagonism on mu(1)-opioid receptor. This finding was corroborated with central administration of nor-binaltorphimine, which also induced a decrease of the fear-like responses

  19. Diencephalic connections of the superior colliculus in the hedgehog tenrec.

    PubMed

    Künzle, H

    1996-10-01

    Using different tracer substances the pathways connecting the superior colliculus with the diencephalon were studied in the Madagascan hedgehog tenrec (Echinops telfairi), a nocturnal insectivore with tiny eyes, a small and little differentiated superior colliculus and a visual cortex with no obvious fourth granular layer. The most prominent tecto-thalamic projection terminated in the ipsilateral dorsal lateral geniculate nucleus. The entire region receiving contralateral retinal afferents was labeled with variable density. In addition, there was a widespread, homogeneously distributed collicular input to the lateralis posterior-pulvinar complex and a distinct tectal projection to the suprageniculate nucleus. The latter projections were bilateral with a clear ipsilateral predominance. Among the intra- and paralaminar nuclei the centralis lateralis complex was most heavily labeled on both sides, followed by the nucleus centralis medialis. The paralamellar portion of the nucleus medialis dorsalis and the nucleus parafascicularis received sparse projections. A clear projection to the nucleus ventralis medialis could not be demonstrated but its presence was not entirely excluded either. There were also projections to medial thalamic nuclei, particularly the reuniens complex and the nucleus paraventricularis thalami. The main tecto-subthalamic target regions were the zona incerta, the dorsal hypothalamus and distinct subdivisons of the ventral lateral geniculate nucleus. These regions also gave rise to projections to the superior colliculus, as did the intergeniculate leaflet. The pathways oriented toward the visual or frontal cortex and the projections possibly involved in limbic and circadian mechanisms were compared with the connectivity patterns reported in mammals with more differentiated brains. Particular attention was given to the tenrec's prominent tecto-geniculate projection, the presumed W- or K-pathway directed toward the supragranular layers. PMID:8911930

  20. Visual modulation of auditory responses in the owl inferior colliculus.

    PubMed

    Bergan, Joseph F; Knudsen, Eric I

    2009-06-01

    The barn owl's central auditory system creates a map of auditory space in the external nucleus of the inferior colliculus (ICX). Although the crucial role visual experience plays in the formation and maintenance of this auditory space map is well established, the mechanism by which vision influences ICX responses remains unclear. Surprisingly, previous experiments have found that in the absence of extensive pharmacological manipulation, visual stimuli do not drive neural responses in the ICX. Here we investigated the influence of dynamic visual stimuli on auditory responses in the ICX. We show that a salient visual stimulus, when coincident with an auditory stimulus, can modulate auditory responses in the ICX even though the same visual stimulus may elicit no neural responses when presented alone. For each ICX neuron, the most effective auditory and visual stimuli were located in the same region of space. In addition, the magnitude of the visual modulation of auditory responses was dependent on the context of the stimulus presentation with novel visual stimuli eliciting consistently larger response modulations than frequently presented visual stimuli. Thus the visual modulation of ICX responses is dependent on the characteristics of the visual stimulus as well as on the spatial and temporal correspondence of the auditory and visual stimuli. These results demonstrate moment-to-moment visual enhancements of auditory responsiveness that, in the short-term, increase auditory responses to salient bimodal stimuli and in the long-term could serve to instruct the adaptive auditory plasticity necessary to maintain accurate auditory orienting behavior. PMID:19321633

  1. Spectral and Temporal Modulation Tradeoff in the Inferior Colliculus

    PubMed Central

    Rodríguez, Francisco A.; Read, Heather L.

    2010-01-01

    The cochlea encodes sounds through frequency-selective channels that exhibit low-pass modulation sensitivity. Unlike the cochlea, neurons in the auditory midbrain are tuned for spectral and temporal modulations found in natural sounds, yet the role of this transformation is not known. We report a distinct tradeoff in modulation sensitivity and tuning that is topographically ordered within the central nucleus of the inferior colliculus (CNIC). Spectrotemporal receptive fields (STRFs) were obtained with 16-channel electrodes inserted orthogonal to the isofrequency lamina. Surprisingly, temporal and spectral characteristics exhibited an opposing relationship along the tonotopic axis. For low best frequencies (BFs), units were selective for fast temporal and broad spectral modulations. A systematic progression was observed toward slower temporal and finer spectral modulation sensitivity at high BF. This tradeoff was strongly reflected in the arrangement of excitation and inhibition and, consequently, in the modulation tuning characteristics. Comparisons with auditory nerve fibers show that these trends oppose the pattern imposed by the peripheral filters. These results suggest that spectrotemporal preferences are reordered within the tonotopic axis of the CNIC. This topographic organization has profound implications for the coding of spectrotemporal features in natural sounds and could underlie a number of perceptual phenomena. PMID:20018831

  2. Lagged cells in the inferior colliculus of the awake ferret

    PubMed Central

    Shechter, Barak; Marvit, Peter; Depireux, Didier A

    2010-01-01

    Neurons in primary auditory cortex (AI) encode complex features of the spectral content of sound, such as direction selectivity. Recent findings of temporal symmetry in AI predict a specific organization of the subcortical input into cortex that contributes to the emergence of direction selectivity. We demonstrate two sub-populations of neurons in the central nucleus of the inferior colliculus, which differ in their steady-state temporal response profile: lagged and non-lagged. The lagged cells (23%) are shifted in temporal phase with respect to non-lagged cells and are characterized by an “inhibition first” and delayed excitation in their spectro-temporal receptive fields. Non-lagged cells (77%) have a canonical “excitation first” response. However, we find no difference in the response onset latency to pure tone stimuli between the two sub-populations. Given the homogeneity of tonal response latency, we predict that these lagged cells receive inhibitory input mediated by cortical feedback projections. PMID:20092554

  3. An Overrepresentation of High Frequencies in the Mouse Inferior Colliculus Supports the Processing of Ultrasonic Vocalizations.

    PubMed

    Garcia-Lazaro, Jose A; Shepard, Kathryn N; Miranda, Jason A; Liu, Robert C; Lesica, Nicholas A

    2015-01-01

    Mice are of paramount importance in biomedical research and their vocalizations are a subject of interest for researchers across a wide range of health-related disciplines due to their increasingly important value as a phenotyping tool in models of neural, speech and language disorders. However, the mechanisms underlying the auditory processing of vocalizations in mice are not well understood. The mouse audiogram shows a peak in sensitivity at frequencies between 15-25 kHz, but weaker sensitivity for the higher ultrasonic frequencies at which they typically vocalize. To investigate the auditory processing of vocalizations in mice, we measured evoked potential, single-unit, and multi-unit responses to tones and vocalizations at three different stages along the auditory pathway: the auditory nerve and the cochlear nucleus in the periphery, and the inferior colliculus in the midbrain. Auditory brainstem response measurements suggested stronger responses in the midbrain relative to the periphery for frequencies higher than 32 kHz. This result was confirmed by single- and multi-unit recordings showing that high ultrasonic frequency tones and vocalizations elicited responses from only a small fraction of cells in the periphery, while a much larger fraction of cells responded in the inferior colliculus. These results suggest that the processing of communication calls in mice is supported by a specialization of the auditory system for high frequencies that emerges at central stations of the auditory pathway. PMID:26244986

  4. An Overrepresentation of High Frequencies in the Mouse Inferior Colliculus Supports the Processing of Ultrasonic Vocalizations

    PubMed Central

    Garcia-Lazaro, Jose A.; Shepard, Kathryn N.; Miranda, Jason A.; Liu, Robert C.; Lesica, Nicholas A.

    2015-01-01

    Mice are of paramount importance in biomedical research and their vocalizations are a subject of interest for researchers across a wide range of health-related disciplines due to their increasingly important value as a phenotyping tool in models of neural, speech and language disorders. However, the mechanisms underlying the auditory processing of vocalizations in mice are not well understood. The mouse audiogram shows a peak in sensitivity at frequencies between 15-25 kHz, but weaker sensitivity for the higher ultrasonic frequencies at which they typically vocalize. To investigate the auditory processing of vocalizations in mice, we measured evoked potential, single-unit, and multi-unit responses to tones and vocalizations at three different stages along the auditory pathway: the auditory nerve and the cochlear nucleus in the periphery, and the inferior colliculus in the midbrain. Auditory brainstem response measurements suggested stronger responses in the midbrain relative to the periphery for frequencies higher than 32 kHz. This result was confirmed by single- and multi-unit recordings showing that high ultrasonic frequency tones and vocalizations elicited responses from only a small fraction of cells in the periphery, while a much larger fraction of cells responded in the inferior colliculus. These results suggest that the processing of communication calls in mice is supported by a specialization of the auditory system for high frequencies that emerges at central stations of the auditory pathway. PMID:26244986

  5. Temporal properties of inferior colliculus neurons to photonic stimulation in the cochlea

    PubMed Central

    Tan, Xiaodong; Young, Hunter; Matic, Agnella Izzo; Zirkle, Whitney; Rajguru, Suhrud; Richter, Claus-Peter

    2015-01-01

    Infrared neural stimulation (INS) may be beneficial in auditory prostheses because of its spatially selective activation of spiral ganglion neurons. However, the response properties of single auditory neurons to INS and the possible contributions of its optoacoustic effects are yet to be examined. In this study, the temporal properties of auditory neurons in the central nucleus of the inferior colliculus (ICC) of guinea pigs in response to INS were characterized. Spatial selectivity of INS was observed along the tonotopically organized ICC. Trains of laser pulses and trains of acoustic clicks were used to evoke single unit responses in ICC of normal hearing animals. In response to INS, ICC neurons showed lower limiting rates, longer latencies, and lower firing efficiencies. In deaf animals, ICC neurons could still be stimulated by INS while unresponsive to acoustic stimulation. The site and spatial selectivity of INS both likely shaped the temporal properties of ICC neurons. PMID:26311831

  6. Responses to amplitude modulated infrared stimuli in the guinea pig inferior colliculus

    PubMed Central

    Richter, Claus-Peter; Young, Hunter

    2014-01-01

    Responses of units in the central nucleus of the inferior colliculus of the guinea pig were recorded with tungsten electrodes. The set of data presented here is limited to high stimulus levels. The effect of changing the modulation frequency and the modulation depth was explored for acoustic and laser stimuli. The selected units responded to sinusoidal amplitude modulated (AM) tones, AM trains of clicks, and AM trains of laser pulses with a modulation of their spike discharge. At modulation frequencies of 20 Hz, some units tended to respond with 40 Hz to the acoustic stimuli, but only at 20 Hz for the trains of laser pulses. For all modes of stimulation the responses revealed a dominant response to the first cycle of the modulation, with decreasing number of action potential during successive cycles. While amplitude modulated tone bursts and amplitude modulated trains of acoustic clicks showed similar patterns, the response to trains of laser pulses was different. PMID:25075264

  7. Investigation of a central nucleus of the amygdala/dorsal raphe nucleus serotonergic circuit implicated in fear-potentiated startle.

    PubMed

    Spannuth, B M; Hale, M W; Evans, A K; Lukkes, J L; Campeau, S; Lowry, C A

    2011-04-14

    Serotonergic systems are thought to play an important role in control of motor activity and emotional states. We used a fear-potentiated startle paradigm to investigate the effects of a motor-eliciting stimulus in the presence or absence of induction of an acute fear state on serotonergic neurons in the dorsal raphe nucleus (DR) and cells in subdivisions of the central amygdaloid nucleus (CE), a structure that plays an important role in fear responses, using induction of the protein product of the immediate-early gene, c-Fos. In Experiment 1 we investigated the effects of fear conditioning training, by training rats to associate a light cue (conditioned stimulus, CS; 1000 lx, 2 s) with foot shock (0.5 s, 0.5 mA) in a single session. In Experiment 2 rats were given two training sessions identical to Experiment 1 on days 1 and 2, then tested in one of four conditions on day 3: (1) placement in the training context without exposure to either the CS or acoustic startle (AS), (2) exposure to 10 trials of the 2 s CS, (3) exposure to 40 110 dB AS trials, or (4) exposure to 40 110 dB AS trials with 10 of the trials preceded by and co-terminating with the CS. All treatments were conducted during a 20 min session. Fear conditioning training, by itself, increased c-Fos expression in multiple subdivisions of the CE and throughout the DR. In contrast, fear-potentiated startle selectively increased c-Fos expression in the medial subdivision of the CE and in serotonergic neurons in the dorsal part of the dorsal raphe nucleus (DRD). These data are consistent with previous studies demonstrating that fear-related stimuli selectively activate DRD serotonergic neurons. Further studies of this mesolimbocortical serotonergic system could have important implications for understanding mechanisms underlying vulnerability to stress-related psychiatric disorders, including anxiety and affective disorders. PMID:21277950

  8. Colour of the nucleus as a marker of nuclear hardness, diameter and central thickness.

    PubMed

    Gullapalli, V K; Murthy, P R; Murthy, K R

    1995-12-01

    Hundred and thirty patients, aged above 40 years, with senile cataract were examined. Age and colour were selected as the probable preoperative indicators of nuclear hardness. The lens material collected after manual extracapsular extraction was washed and the nucleus isolated. The diameter and central thickness of the nucleus were measured; the mean diameter and mean central thickness were 7.13 mm +/- 0.76 and 3.05 mm +/- 0.48, respectively. The hardness of the nucleus was measured with a lens guillotine designed by us. Regression analysis was applied to the parameters measured and these were compared with the colour and age. The parameters measured had the following relationship: Colour vs hardness (r value = 0.7569) (p < 0.001) Colour vs diameter (r value = 0.3962) (p < 0.001) Colour vs central thickness (r value = 0.4785) (p < 0.001) Age vs hardness (r value = -0.0499) (p > 0.05) Age vs diameter (r value = 0.0987) (p > 0.05) Age vs central thickness (r value = 0.1700) (p > 0.05) The values showed that colour had a statistically significant relationship with all the 3 parameters (p < 0.001), while age had no significant relationship with the same parameters. The results indicated that colour can be used more reliably to predict physical characteristics of the cataractous lens nucleus, the preoperative knowledge of which would help the surgeon in planning small-incision surgery including phacoemulsification. PMID:8655196

  9. Baroreflex failure in a patient with central nervous system lesions involving the nucleus tractus solitarii

    NASA Technical Reports Server (NTRS)

    Biaggioni, I.; Whetsell, W. O.; Jobe, J.; Nadeau, J. H.

    1994-01-01

    Animal studies have shown the importance of the nucleus tractus solitarii, a collection of neurons in the brain stem, in the acute regulation of blood pressure. Impulses arising from the carotid and aortic baroreceptors converge in this center, where the first synapse of the baroreflex is located. Stimulation of the nucleus tractus solitarii provides an inhibitory signal to other brain stem structures, particularly the rostral ventrolateral medulla, resulting in a reduction in sympathetic outflow and a decrease in blood pressure. Conversely, experimental lesions of the nucleus tractus solitarii lead to loss of baroreflex control of blood pressure, sympathetic activation, and severe hypertension in animals. In humans, baroreflex failure due to deafferentation of baroreceptors has been previously reported and is characterized by episodes of severe hypertension and tachycardia. We present a patient with an undetermined process of the central nervous system characterized pathologically by ubiquitous infarctions that were particularly prominent in the nucleus tractus solitarii bilaterally but spared the rostral ventrolateral medulla. Absence of a functioning baroreflex was evidenced by the lack of reflex tachycardia to the hypotensive effects of sodium nitroprusside, exaggerated pressor responses to handgrip and cold pressor test, and exaggerated depressor responses to meals and centrally acting alpha 2-agonists. This clinicopathological correlate suggests that the patient's baroreflex failure can be explained by the unique combination of the destruction of sympathetic inhibitory centers (ie, the nucleus tractus solitarii) and preservation of centers that exert a positive modulation on sympathetic tone (ie, the rostral ventrolateral medulla).

  10. Centrality-dependent forward J/ψ production in high energy proton-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Ducloué, B.; Lappi, T.; Mäntysaari, H.

    2016-03-01

    Forward J/ψ production and suppression in high energy proton-nucleus collisions can be an important probe of gluon saturation. In an earlier work we studied this process in the Color Glass Condensate framework and showed that using the Glauber approach to extrapolate the dipole cross section of a proton to a nucleus leads to results closer to experimental data than previous calculations in this framework. Here we investigate the centrality dependence of the nuclear suppression in this model and show a comparison of our results with recent LHC data.

  11. Protein tyrosine phosphatases expression during development of mouse superior colliculus.

    PubMed

    Reinhard, Jacqueline; Horvat-Bröcker, Andrea; Illes, Sebastian; Zaremba, Angelika; Knyazev, Piotr; Ullrich, Axel; Faissner, Andreas

    2009-12-01

    Protein tyrosine phosphatases (PTPs) are key regulators of different processes during development of the central nervous system. However, expression patterns and potential roles of PTPs in the developing superior colliculus remain poorly investigated. In this study, a degenerate primer-based reverse transcription-polymerase chain reaction (RT-PCR) approach was used to isolate seven different intracellular PTPs and nine different receptor-type PTPs (RPTPs) from embryonic E15 mouse superior colliculus. Subsequently, the expression patterns of 11 PTPs (TC-PTP, PTP1C, PTP1D, PTP-MEG2, PTP-PEST, RPTPJ, RPTPε, RPTPRR, RPTPσ, RPTPκ and RPTPγ) were further analyzed in detail in superior colliculus from embryonic E13 to postnatal P20 stages by quantitative real-time RT-PCR, Western blotting and immunohistochemistry. Each of the 11 PTPs exhibits distinct spatiotemporal regulation of mRNAs and proteins in the developing superior colliculus suggesting their versatile roles in genesis of neuronal and glial cells and retinocollicular topographic mapping. At E13, additional double-immunohistochemical analysis revealed the expression of PTPs in collicular nestin-positive neural progenitor cells and RC-2-immunoreactive radial glia cells, indicating the potential functional importance of PTPs in neurogenesis and gliogenesis. PMID:19727691

  12. Connections of the superior colliculus with the tegmentum and the cerebellum in the hedgehog tenrec.

    PubMed

    Künzle, H

    1997-06-01

    Different tracer substances were injected into the superior colliculus (CoS) in order to study its afferents and efferents with the meso-rhombencephalic tegmentum, the precerebellar nuclei and the cerebellum in the Madagascan hedgehog tenrec. The overall pattern of tectal connectivity in tenrec was similar to that in other mammals, as, e.g. the efferents to the contralateral paramedian reticular formation. Similarly the origin of the cerebello-tectal projection in mainly the lateral portions of the tenrec's cerebellar nuclear complex corresponded to the findings in species with little binocular overlap. In comparison to other mammals, however, the tenrec showed a consistent projection to the ipsilateral inferior olivary nucleus, in addition to the classical contralateral tecto-olivary projection. The tenrec's CoS also appeared to receive an unusually prominent monoaminergic input particularly from the substantia nigra, pars compacta. There was a reciprocal tecto-parabigeminal projection, a distinct nuclear aggregation of parabigeminal neurons, however, was difficult to identify. The dorsal lemniscal nucleus did not show perikaryal labeling in contrast to the paralemniscal region. Similar to the cat but unlike the rat there were a few neurons in the nucleus of the central acoustic tract. Unlike the cat, but similar to the rat there was a distinct, predominantly ipsilateral projection to the magnocellular reticular field known to project spinalward. PMID:9220470

  13. Genetic identification of the central nucleus and other components of the central extended amygdala in chicken during development

    PubMed Central

    Vicario, Alba; Abellán, Antonio; Desfilis, Ester; Medina, Loreta

    2014-01-01

    In mammals, the central extended amygdala shows a highly complex organization, and is essential for animal survival due to its implication in fear responses. However, many aspects of its evolution are still unknown, and this structure is especially poorly understood in birds. The aim of this study was to define the central extended amygdala in chicken, by means of a battery of region-specific transcription factors (Pax6, Islet1, Nkx2.1) and phenotypic markers that characterize these different subdivisions in mammals. Our results allowed the identification of at least six distinct subdivisions in the lateral part of the avian central extended amygdala: (1) capsular central subdivision; (2) a group of intercalated-like cell patches; (3) oval central nucleus; (4) peri-intrapeduncular (peri-INP) island field; (5) perioval zone; and (6) a rostral part of the subpallial extended amygdala. In addition, we identified three subdivisions of the laterodorsal bed nucleus of the stria terminalis (BSTLd) belonging to the medial region of the chicken central extended amygdala complex. Based on their genetic profile, cellular composition and apparent embryonic origin of the cells, we discuss the similarity of these different subdivisions of chicken with different parts of the mouse central amygdala and surrounding cell masses, including the intercalated amygdalar masses and the sublenticular part of the central extended amygdala. Most of the subdivisions include various subpopulations of cells that apparently originate in the dorsal striatal, ventral striatal, pallidal, and preoptic embryonic domains, reaching their final location by either radial or tangential migrations. Similarly to mammals, the central amygdala and BSTLd of chicken project to the hypothalamus, and include different neurons expressing proenkephalin, corticotropin-releasing factor, somatostatin or tyrosine hydroxylase, which may be involved in the control of different aspects of fear/anxiety-related behavior

  14. The centrally projecting Edinger-Westphal nucleus--I: Efferents in the rat brain.

    PubMed

    Dos Santos Júnior, Edmilson D; Da Silva, André V; Da Silva, Kelly R T; Haemmerle, Carlos A S; Batagello, Daniella S; Da Silva, Joelcimar M; Lima, Leandro B; Da Silva, Renata J; Diniz, Giovanne B; Sita, Luciane V; Elias, Carol F; Bittencourt, Jackson C

    2015-10-01

    The oculomotor accessory nucleus, often referred to as the Edinger-Westphal nucleus [EW], was first identified in the 17th century. Although its most well known function is the control of pupil diameter, some controversy has arisen regarding the exact location of these preganglionic neurons. Currently, the EW is thought to consist of two different parts. The first part [termed the preganglionic EW-EWpg], which controls lens accommodation, choroidal blood flow and pupillary constriction, primarily consists of cholinergic cells that project to the ciliary ganglion. The second part [termed the centrally projecting EW-EWcp], which is involved in non-ocular functions such as feeding behavior, stress responses, addiction and pain, consists of peptidergic neurons that project to the brainstem, the spinal cord and prosencephalic regions. However, in the literature, we found few reports related to either ascending or descending projections from the EWcp that are compatible with its currently described functions. Therefore, the objective of the present study was to systematically investigate the ascending and descending projections of the EW in the rat brain. We injected the anterograde tracer biotinylated dextran amine into the EW or the retrograde tracer cholera toxin subunit B into multiple EW targets as controls. Additionally, we investigated the potential EW-mediated innervation of neuronal populations with known neurochemical signatures, such as melanin-concentrating hormone in the lateral hypothalamic area [LHA] and corticotropin-releasing factor in the central nucleus of the amygdala [CeM]. We observed anterogradely labeled fibers in the LHA, the reuniens thalamic nucleus, the oval part of the bed nucleus of the stria terminalis, the medial part of the central nucleus of the amygdala, and the zona incerta. We confirmed our EW-LHA and EW-CeM connections using retrograde tracers. We also observed moderate EW-mediated innervation of the paraventricular nucleus of the

  15. A periodic network of neurochemical modules in the inferior colliculus.

    PubMed

    Chernock, Michelle L; Larue, David T; Winer, Jeffery A

    2004-02-01

    A new organization has been found in shell nuclei of rat inferior colliculus. Chemically specific modules with a periodic distribution fill about half of layer 2 of external cortex and dorsal cortex. Modules contain clusters of small glutamic acid decarboxylase-positive neurons and large boutons at higher density than in other inferior colliculus subdivisions. The modules are also present in tissue stained for parvalbumin, cytochrome oxidase, nicotinamide adenine dinucleotide phosphate-diaphorase, and acetylcholinesterase. Six to seven bilaterally symmetrical modules extend from the caudal extremity of the external cortex of the inferior colliculus to its rostral pole. Modules are from approximately 800 to 2200 microm long and have areas between 5000 and 40,000 microm2. Modules alternate with immunonegative regions. Similar modules are found in inbred and outbred strains of rat, and in both males and females. They are absent in mouse, squirrel, cat, bat, macaque monkey, and barn owl. Modules are immunonegative for glycine, calbindin, serotonin, and choline acetyltransferase. The auditory cortex and ipsi- and contralateral inferior colliculi project to the external cortex. Somatic sensory influences from the dorsal column nuclei and spinal trigeminal nucleus are the primary ascending sensory input to the external cortex; ascending auditory input to layer 2 is sparse. If the immunopositive modular neurons receive this input, the external cortex could participate in spatial orientation and somatic motor control through its intrinsic and extrinsic projections. PMID:14759566

  16. The representation of sound localization cues in the barn owl's inferior colliculus.

    PubMed

    Singheiser, Martin; Gutfreund, Yoram; Wagner, Hermann

    2012-01-01

    The barn owl is a well-known model system for studying auditory processing and sound localization. This article reviews the morphological and functional organization, as well as the role of the underlying microcircuits, of the barn owl's inferior colliculus (IC). We focus on the processing of frequency and interaural time (ITD) and level differences (ILD). We first summarize the morphology of the sub-nuclei belonging to the IC and their differentiation by antero- and retrograde labeling and by staining with various antibodies. We then focus on the response properties of neurons in the three major sub-nuclei of IC [core of the central nucleus of the IC (ICCc), lateral shell of the central nucleus of the IC (ICCls), and the external nucleus of the IC (ICX)]. ICCc projects to ICCls, which in turn sends its information to ICX. The responses of neurons in ICCc are sensitive to changes in ITD but not to changes in ILD. The distribution of ITD sensitivity with frequency in ICCc can only partly be explained by optimal coding. We continue with the tuning properties of ICCls neurons, the first station in the midbrain where the ITD and ILD pathways merge after they have split at the level of the cochlear nucleus. The ICCc and ICCls share similar ITD and frequency tuning. By contrast, ICCls shows sigmoidal ILD tuning which is absent in ICCc. Both ICCc and ICCls project to the forebrain, and ICCls also projects to ICX, where space-specific neurons are found. Space-specific neurons exhibit side peak suppression in ITD tuning, bell-shaped ILD tuning, and are broadly tuned to frequency. These neurons respond only to restricted positions of auditory space and form a map of two-dimensional auditory space. Finally, we briefly review major IC features, including multiplication-like computations, correlates of echo suppression, plasticity, and adaptation. PMID:22798945

  17. The representation of sound localization cues in the barn owl's inferior colliculus

    PubMed Central

    Singheiser, Martin; Gutfreund, Yoram; Wagner, Hermann

    2012-01-01

    The barn owl is a well-known model system for studying auditory processing and sound localization. This article reviews the morphological and functional organization, as well as the role of the underlying microcircuits, of the barn owl's inferior colliculus (IC). We focus on the processing of frequency and interaural time (ITD) and level differences (ILD). We first summarize the morphology of the sub-nuclei belonging to the IC and their differentiation by antero- and retrograde labeling and by staining with various antibodies. We then focus on the response properties of neurons in the three major sub-nuclei of IC [core of the central nucleus of the IC (ICCc), lateral shell of the central nucleus of the IC (ICCls), and the external nucleus of the IC (ICX)]. ICCc projects to ICCls, which in turn sends its information to ICX. The responses of neurons in ICCc are sensitive to changes in ITD but not to changes in ILD. The distribution of ITD sensitivity with frequency in ICCc can only partly be explained by optimal coding. We continue with the tuning properties of ICCls neurons, the first station in the midbrain where the ITD and ILD pathways merge after they have split at the level of the cochlear nucleus. The ICCc and ICCls share similar ITD and frequency tuning. By contrast, ICCls shows sigmoidal ILD tuning which is absent in ICCc. Both ICCc and ICCls project to the forebrain, and ICCls also projects to ICX, where space-specific neurons are found. Space-specific neurons exhibit side peak suppression in ITD tuning, bell-shaped ILD tuning, and are broadly tuned to frequency. These neurons respond only to restricted positions of auditory space and form a map of two-dimensional auditory space. Finally, we briefly review major IC features, including multiplication-like computations, correlates of echo suppression, plasticity, and adaptation. PMID:22798945

  18. Estrogen synthesis in the central nucleus of the amygdala following middle cerebral artery occlusion: role in modulating neurotransmission.

    PubMed

    Saleh, T M; Connell, B J; Legge, C; Cribb, A E

    2005-01-01

    Stroke-induced lesions of the insular cortex in the brain have been linked to autonomic dysfunction (sympathoexcitation) leading to arrhythmogenesis and sudden cardiac death. In experimental models, systemic estrogen administration in male rats has been shown to reduce stroke-induced cell death in the insular cortex as well as prevent sympathoexcitation. The central nucleus of the amygdala has been postulated to mediate sympathoexcitatory output from the insular cortex. We therefore set out to determine if endogenous estrogen levels within the central nucleus of the amygdala are altered following stroke and if microinjection of estrogen into the central nucleus of the amygdala modulates autonomic tone. Plasma estrogen concentrations were not altered by middle cerebral artery occlusion (22.86+/-0.14 pg/ml vs. 21.24+/-0.33 pg/ml; P>0.05). In contrast, estrogen concentrations in the central nucleus of the amygdala increased significantly following middle cerebral artery occlusion (from 20.83+/-0.54 pg/ml to 76.67+/-1.59 pg/ml; P<0.05). Local infusion of an aromatase inhibitor, letrozole, into the central nucleus of the amygdala at the time of middle cerebral artery occlusion prevented the increase in estrogen concentration suggesting that this increase was dependent on aromatization from testosterone. Furthermore, bilateral microinjection of estrogen (0.5 microM in 200 nl) directly into the central nucleus of the amygdala significantly decreased arterial pressure and sympathetic tone and increased baroreflex sensitivity, and these effects were enhanced following co-injection with either an N-methyl-D-aspartate or non-N-methyl-D-aspartate receptor antagonist. Taken together, the results suggest that middle cerebral artery occlusion resulted in synthesis of estrogen within the central nucleus of the amygdala and that this enhanced estrogen level may act to attenuate overstimulation of central nucleus of the amygdala neurons to prevent middle cerebral artery occlusion

  19. Effects of unilateral acoustic trauma on tinnitus-related spontaneous activity in the inferior colliculus.

    PubMed

    Ropp, Tessa-Jonne F; Tiedemann, Kerrie L; Young, Eric D; May, Bradford J

    2014-12-01

    This study describes the long-term effects of sound-induced cochlear trauma on spontaneous discharge rates in the central nucleus of the inferior colliculus (ICC). As in previous studies, single-unit recordings in Sprague-Dawley rats revealed pervasive increases in spontaneous discharge rates. Based on differences in their sources of input, it was hypothesized that physiologically defined neural populations of the auditory midbrain would reveal the brainstem sources that dictate ICC hyperactivity. Abnormal spontaneous activity was restricted to target neurons of the ventral cochlear nucleus. Nearly identical patterns of hyperactivity were observed in the contralateral and ipsilateral ICC. The elevation in spontaneous activity extended to frequencies well below and above the region of maximum threshold shift. This lack of frequency organization suggests that ICC hyperactivity may be influenced by regions of the brainstem that are not tonotopically organized. Sound-induced hyperactivity is often observed in animals with behavioral signs of tinnitus. Prior to electrophysiological recording, rats were screened for tinnitus by measuring gap pre-pulse inhibition of the acoustic startle reflex (GPIASR). Rats with positive phenotypes did not exhibit unique patterns of ICC hyperactivity. This ambiguity raises concerns regarding animal behavioral models of tinnitus. If our screening procedures were valid, ICC hyperactivity is observed in animals without behavioral indications of the disorder. Alternatively, if the perception of tinnitus is strictly linked to ongoing ICC hyperactivity, our current behavioral approach failed to provide a reliable assessment of tinnitus state. PMID:25255865

  20. ON and OFF inhibition as mechanisms for forward masking in the inferior colliculus: a modeling study.

    PubMed

    Gai, Yan

    2016-06-01

    Masking effects of a preceding stimulus on the detection or perception of a signal have been found in several sensory systems in mammals, including humans and rodents. In the auditory system, it has been hypothesized that a central "OFF-inhibitory" mechanism, which is generated by neurons that respond after a sound is terminated, may contribute to the observed psychophysics. The present study constructed a systems model for the inferior colliculus that includes major ascending monaural and binaural auditory pathways. The fundamental characteristics of several neuron types along the pathways were captured by Hodgkin-Huxley models with specific membrane and synaptic properties. OFF responses were reproduced with a model of the superior paraolivary nucleus containing a hyperpolarization-activated h current and a T-type calcium current. When the gap between the end of the masker and the onset of the signal was large, e.g., >5 ms, OFF inhibition generated strong suppressive effects on the signal response. For smaller gaps, an additional inhibitory source, which was modeled as ON inhibition from the contralateral dorsal nucleus of the lateral lemniscus, showed the potential of explaining the psychophysics. Meanwhile, the effect of a forward masker on the binaural sensitivity to a low-frequency signal was examined, which was consistent with previous psychophysical findings related to sound localization. PMID:26912597

  1. Immunocytochemical profiles of inferior colliculus neurons in the rat and their changes with aging

    PubMed Central

    Ouda, Ladislav; Syka, Josef

    2012-01-01

    The inferior colliculus (IC) plays a strategic role in the central auditory system in relaying and processing acoustical information, and therefore its age-related changes may significantly influence the quality of the auditory function. A very complex processing of acoustical stimuli occurs in the IC, as supported also by the fact that the rat IC contains more neurons than all other subcortical auditory structures combined. GABAergic neurons, which predominantly co-express parvalbumin (PV), are present in the central nucleus of the IC in large numbers and to a lesser extent in the dorsal and external/lateral cortices of the IC. On the other hand, calbindin (CB) and calretinin (CR) are prevalent in the dorsal and external cortices of the IC, with only a few positive neurons in the central nucleus. The relationship between CB and CR expression in the IC and any neurotransmitter system has not yet been well established, but the distribution and morphology of the immunoreactive neurons suggest that they are at least partially non-GABAergic cells. The expression of glutamate decarboxylase (GAD) (a key enzyme for GABA synthesis) and calcium binding proteins (CBPs) in the IC of rats undergoes pronounced changes with aging that involve mostly a decline in protein expression and a decline in the number of immunoreactive neurons. Similar age-related changes in GAD, CB, and CR expression are present in the IC of two rat strains with differently preserved inner ear function up to late senescence (Long-Evans and Fischer 344), which suggests that these changes do not depend exclusively on peripheral deafferentation but are, at least partially, of central origin. These changes may be associated with the age-related deterioration in the processing of the temporal parameters of acoustical stimuli, which is not correlated with hearing threshold shifts, and therefore may contribute to central presbycusis. PMID:23049499

  2. Enhancement of forward suppression begins in the ventral cochlear nucleus.

    PubMed

    Ingham, Neil J; Itatani, Naoya; Bleeck, Stefan; Winter, Ian M

    2016-05-15

    A neuron׳s response to a sound can be suppressed by the presentation of a preceding sound. It has been suggested that this suppression is a direct correlate of the psychophysical phenomenon of forward masking, however, forward suppression, as measured in the responses of the auditory nerve, was insufficient to account for behavioural performance. In contrast the neural suppression seen in the inferior colliculus and auditory cortex was much closer to psychophysical performance. In anaesthetised guinea-pigs, using a physiological two-interval forced-choice threshold tracking algorithm to estimate suppressed (masked) thresholds, we examine whether the enhancement of suppression can occur at an earlier stage of the auditory pathway, the ventral cochlear nucleus (VCN). We also compare these responses with the responses from the central nucleus of the inferior colliculus (ICc) using the same preparation. In both nuclei, onset-type neurons showed the greatest amounts of suppression (16.9-33.5dB) and, in the VCN, these recovered with the fastest time constants (14.1-19.9ms). Neurons with sustained discharge demonstrated reduced masking (8.9-12.1dB) and recovery time constants of 27.2-55.6ms. In the VCN the decrease in growth of suppression with increasing suppressor level was largest for chopper units and smallest for onset-type units. The threshold elevations recorded for most unit types are insufficient to account for the magnitude of forward masking as measured behaviourally, however, onset responders, in both the cochlear nucleus and inferior colliculus demonstrate a wide dynamic range of suppression, similar to that observed in human psychophysics. PMID:26944300

  3. Removing Cool Cores and Central Metallicity Peaks in Galaxy Clusters with Powerful Active Galactic Nucleus Outbursts

    NASA Astrophysics Data System (ADS)

    Guo, Fulai; Mathews, William G.

    2010-07-01

    Recent X-ray observations of galaxy clusters suggest that cluster populations are bimodally distributed according to central gas entropy and are separated into two distinct classes: cool core (CC) and non-cool core (NCC) clusters. While it is widely accepted that active galactic nucleus (AGN) feedback plays a key role in offsetting radiative losses and maintaining many clusters in the CC state, the origin of NCC clusters is much less clear. At the same time, a handful of extremely powerful AGN outbursts have recently been detected in clusters, with a total energy ~1061-1062 erg. Using two-dimensional hydrodynamic simulations, we show that if a large fraction of this energy is deposited near the centers of CC clusters, which is likely common due to dense cores, these AGN outbursts can completely remove CCs, transforming them to NCC clusters. Our model also has interesting implications for cluster abundance profiles, which usually show a central peak in CC systems. Our calculations indicate that during the CC to NCC transformation, AGN outbursts efficiently mix metals in cluster central regions and may even remove central abundance peaks if they are not broad enough. For CC clusters with broad central abundance peaks, AGN outbursts decrease peak abundances, but cannot effectively destroy the peaks. Our model may simultaneously explain the contradictory (possibly bimodal) results of abundance profiles in NCC clusters, some of which are nearly flat, while others have strong central peaks similar to those in CC clusters. A statistical analysis of the sizes of central abundance peaks and their redshift evolution may shed interesting insights on the origin of both types of NCC clusters and the evolution history of thermodynamics and AGN activity in clusters.

  4. Functional organization of mustached bat inferior colliculus: I. Representation of FM frequency bands important for target ranging revealed by 14C-2-deoxyglucose autoradiography and single unit mapping.

    PubMed

    O'Neill, W E; Frisina, R D; Gooler, D M

    1989-06-01

    The representation in the inferior colliculus of the frequency modulated (FM) components of the first (25-30 kHz) and second (50-60 kHz) harmonic of the sonar signal of the mustached bat, which may be important for target range processing, was investigated by using the 2-deoxyglucose (2-DG) technique and single-unit mapping. In the 2-DG experiments, bats presented with second harmonic FM stimuli alone showed uptake of label in specific regions of the central nucleus and dorsal cortex of the inferior colliculus, and the nucleus of the brachium. In the central nucleus, a dorsoventrally and mediolaterally elongated slab at the caudal border of the anterolateral division was observed. Labeling in the dorsal cortex was contiguous with this band. Bats stimulated with pairs of first and second harmonic FM stimuli separated by short time delays showed similar patterns of labeling, with the addition of another dorsoventrally elongated region of uptake in the more rostral part of the anterolateral division, associated with label in the dorsal cortex. By comparison to control cases exposed to delayed pairs of first and third harmonic signals, or to a second harmonic constant-frequency tone burst at the bat's reference frequency (ca. 60 kHz), we deduced that this additional region of uptake was attributable to the first harmonic FM component. To elucidate further the details of the tonotopic organization and to correlate the frequency representation with anatomical features of the IC, fine-grained maps of single-unit best frequencies were obtained in the central nucleus. Isofrequency contours were reconstructed by computer from five bats after focal, iontophoretic injection of horseradish peroxidase to locate the penetrations and trace connections of the FM2 area. We found that the tissue volume representing FM2 frequencies (50-60 kHz) showed approximately a sixfold overrepresentation for this frequency band. This region occupied most of the caudal portion of the anterolateral

  5. Topographic projection from the optic tectum to the auditory space map in the inferior colliculus of the barn owl.

    PubMed

    Hyde, P S; Knudsen, E I

    2000-05-29

    In the barn owl (Tyto alba), the external nucleus of the inferior colliculus (ICX) contains a map of auditory space that is calibrated by visual experience. The source of the visually based instructive signal to the ICX is unknown. Injections of biotinylated dextran amine and Fluoro-Gold in the ICX retrogradely labelled neurons in layers 8-15 of the ipsilateral optic tectum (OT) that could carry this instructive signal. This projection was point-to-point and in register with the feed-forward, auditory projection from the ICX to the OT. Most labelled neurons were in layers 10-11, and most were bipolar. Tripolar, multipolar, and unipolar neurons were also observed. Multipolar neurons had dendrites that were oriented parallel to the tectal laminae. In contrast, most labelled bipolar and tripolar neurons had dendrites oriented perpendicular to the tectal laminae, extending superficially into the retino-recipient laminae and deep into the auditory recipient laminae. Therefore, these neurons were positioned to receive both visual and auditory information from particular locations in space. Biocytin injected into the superficial layers of the OT labelled bouton-laden axons in the ICX. These axons were generally finer than, but had similar bouton densities as, feed-forward auditory fibers in the ICX, labelled by injections of biocytin into the central nucleus of the inferior colliculus (ICC). These data demonstrate a point-to-point projection from the OT to the ICX that could provide a spatial template for calibrating the auditory space map in the ICX. PMID:10813778

  6. Serotonin in the inferior colliculus.

    PubMed

    Hurley, Laura M; Thompson, Ann M; Pollak, George D

    2002-06-01

    It has been recognized for some time that serotonin fibers originating in raphe nuclei are present in the inferior colliculi of all mammalian species studied. More recently, serotonin has been found to modulate the responses of single inferior colliculus neurons to many types of auditory stimuli, ranging from simple tone bursts to complex species-specific vocalizations. The effects of serotonin are often quite strong, and for some neurons are also highly specific. A dramatic illustration of this is that serotonin can change the selectivity of some neurons for sounds, including species-specific vocalizations. These results are discussed in light of several theories on the function of serotonin in the IC, and of outstanding issues that remain to be addressed. PMID:12117504

  7. Neural correlates of two different types of extinction learning in the amygdala central nucleus.

    PubMed

    Iordanova, Mihaela D; Deroche, Mickael L D; Esber, Guillem R; Schoenbaum, Geoffrey

    2016-01-01

    Extinction is a fundamental form of memory updating in which one learns to stop expecting an event that no longer occurs. This learning ensues when one experiences a change in environmental contingencies, that is, when an expected outcome fails to occur (simple extinction), or when a novel inflated expectation of a double outcome (overexpectation) is in conflict with the real outcome, and is a process that has been linked to amygdala function. Here, we show that in rats, the same neuronal population in the amygdala central nucleus updates reward expectancies and behaviour in both types of extinction, and neural changes in one paradigm are reflected in the other. This work may have implications for the management of addiction and anxiety disorders that require treatments based on the outcome omission, and disorders such as obesity that could use overexpectation, but not omission strategies. PMID:27531638

  8. Constructing the suprachiasmatic nucleus: a watchmaker's perspective on the central clockworks

    PubMed Central

    Bedont, Joseph L.; Blackshaw, Seth

    2015-01-01

    The circadian system constrains an organism's palette of behaviors to portions of the solar day appropriate to its ecological niche. The central light-entrained clock in the suprachiasmatic nucleus (SCN) of the mammalian circadian system has evolved a complex network of interdependent signaling mechanisms linking multiple distinct oscillators to serve this crucial function. However, studies of the mechanisms controlling SCN development have greatly lagged behind our understanding of its physiological functions. We review advances in the understanding of adult SCN function, what has been described about SCN development to date, and the potential of both current and future studies of SCN development to yield important insights into master clock function, dysfunction, and evolution. PMID:26005407

  9. Neural correlates of two different types of extinction learning in the amygdala central nucleus

    PubMed Central

    Iordanova, Mihaela D.; Deroche, Mickael L. D.; Esber, Guillem R.; Schoenbaum, Geoffrey

    2016-01-01

    Extinction is a fundamental form of memory updating in which one learns to stop expecting an event that no longer occurs. This learning ensues when one experiences a change in environmental contingencies, that is, when an expected outcome fails to occur (simple extinction), or when a novel inflated expectation of a double outcome (overexpectation) is in conflict with the real outcome, and is a process that has been linked to amygdala function. Here, we show that in rats, the same neuronal population in the amygdala central nucleus updates reward expectancies and behaviour in both types of extinction, and neural changes in one paradigm are reflected in the other. This work may have implications for the management of addiction and anxiety disorders that require treatments based on the outcome omission, and disorders such as obesity that could use overexpectation, but not omission strategies. PMID:27531638

  10. The Zona Incerta Regulates Communication between the Superior Colliculus and the Posteromedial Thalamus: Implications for Thalamic Interactions with the Dorsolateral Striatum

    PubMed Central

    Watson, Glenn D.R.; Smith, Jared B.

    2015-01-01

    There is uncertainty concerning the circuit connections by which the superior colliculus interacts with the basal ganglia. To address this issue, anterograde and retrograde tracers were placed, respectively, into the superior colliculus and globus pallidus of Sprague-Dawley rats. In this two-tracer experiment, the projections from the superior colliculus terminated densely in the ventral zona incerta (ZIv), but did not overlap the labeled neurons observed in the subthalamic nucleus. In cases in which anterograde and retrograde tracers were placed, respectively, in sensory-responsive sites in the superior colliculus and posteromedial (POm) thalamus, the labeled projections from superior colliculus innervated the ZIv regions that contained the labeled neurons that project to POm. We also confirmed this colliculo–incertal–POm pathway by depositing a mixture of retrograde and anterograde tracers at focal sites in ZIv to reveal retrogradely labeled neurons in superior colliculus and anterogradely labeled terminals in POm. When combined with retrograde tracer injections in POm, immunohistochemical processing proved that most ZIv projections to POm are GABAergic. Consistent with these findings, direct stimulation of superior colliculus evoked neuronal excitation in ZIv and caused inhibition of spontaneous activity in POm. Collectively, these results indicate that superior colliculus can activate the inhibitory projections from ZIv to the POm. This is significant because it suggests that the superior colliculus could suppress the interactions between POm and the dorsolateral striatum, presumably to halt ongoing behaviors so that more adaptive motor actions are selected in response to unexpected sensory events. SIGNIFICANCE STATEMENT By demonstrating that the zona incerta regulates communication between the superior colliculus and the posteromedial thalamus, we have uncovered a circuit that partly explains the behavioral changes that occur in response to unexpected

  11. BAR EFFECTS ON CENTRAL STAR FORMATION AND ACTIVE GALACTIC NUCLEUS ACTIVITY

    SciTech Connect

    Oh, Seulhee; Oh, Kyuseok; Yi, Sukyoung K.

    2012-01-01

    Galactic bars are often suspected to be channels of gas inflow to the galactic center and to trigger central star formation and active galactic nucleus (AGN) activity. However, the current status on this issue based on empirical studies is unsettling, especially regarding AGNs. We investigate this question based on the Sloan Digital Sky Survey Data Release 7. From the nearby (0.01 < z < 0.05) bright (M{sub r} < -19) database, we have constructed a sample of 6658 relatively face-on late-type galaxies through visual inspection. We found 36% of them to have a bar. Bars are found to be more common in galaxies with earlier morphology. This makes sample selection critical. Parameter-based selections would miss a large fraction of barred galaxies of early morphology. Bar effects on star formation or AGNs are difficult to understand properly because multiple factors (bar frequency, stellar mass, black hole mass, gas contents, etc.) seem to contribute to them in intricate manners. In the hope of breaking these degeneracies, we inspect bar effects for fixed galaxy properties. Bar effects on central star formation seem higher in redder galaxies. Bar effects on AGNs on the other hand are higher in bluer and less massive galaxies. These effects seem more pronounced with increasing bar length. We discuss possible implications in terms of gas contents, bar strength, bar evolution, fueling timescale, and the dynamical role of supermassive black hole.

  12. Paraventricular nucleus is involved in the central pathway of adipose afferent reflex in rats.

    PubMed

    Shi, Zhen; Wang, Yuan-Fang; Wang, Gui-Hua; Wu, Yu-Long; Ma, Chun-Lei

    2016-05-01

    Increasing evidence indicates a link between sympathetic nervous system activation and obesity, but the underlying mechanisms remain elusive. The adipose afferent reflex (AAR) is a sympathoexcitatory reflex that is activated by afferent neurotransmission from the white adipose tissue (WAT). This study aimed to investigate whether the hypothalamic paraventricular nucleus (PVH) is an important component of the central neurocircuitry of the AAR. In anesthetized rats, the discharge activity of individual PVH neurons was recorded in vivo. Activation of WAT afferents was initiated by capsaicin injection, and the AAR was evaluated by monitoring renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses. The responses of PVH neurons to activation of WAT afferents were evaluated by c-fos immunoreactivity and the discharge activity of individual PVH neurons, which was recorded using extracellular single-unit recording. After activation of WAT afferents, both individual PVH neuron discharge activity and c-fos immunoreactivity increased. Bilateral selective lesions of the neurons in the PVH with kainic acid abolished the AAR. These results indicate that PVH is an important component of the central neurocircuitry of the AAR. PMID:26963333

  13. Tonotopic changes in GABA receptor expression in guinea pig inferior colliculus after partial unilateral hearing loss.

    PubMed

    Dong, S; Rodger, J; Mulders, W H A M; Robertson, D

    2010-06-25

    Immunohistochemistry was used to investigate the topographic distribution of the alpha1 subunit of the GABA receptor (GABRA1) in guinea pig inferior colliculus after treatments that caused a unilateral loss of peripheral neural sensitivity in the high-frequency regions of the cochlea. Both forms of treatment (direct mechanical lesion of the cochlea and acoustic overstimulation) resulted in a significant decrease in GABRA1 labeling in regions of the contralateral inferior colliculus in which high-frequency sound stimuli are represented. This localized region of reduced inhibitory receptor expression corresponds to the region in which hyperactivity of inferior colliculus neurons has been shown to develop after such treatments. The results strengthen the notion of a causal link between reduced GABRA1 expression and neural hyperactivity in central auditory nuclei and provide a possible mechanism for the development of phantom auditory sensations, or tinnitus. PMID:20438718

  14. Stress increases GABAergic neurotransmission in CRF neurons of the central amygdala and bed nucleus stria terminalis.

    PubMed

    Partridge, John G; Forcelli, Patrick A; Luo, Ruixi; Cashdan, Jonah M; Schulkin, Jay; Valentino, Rita J; Vicini, Stefano

    2016-08-01

    Corticotrophin Releasing Factor (CRF) is a critical stress-related neuropeptide in major output pathways of the amygdala, including the central nucleus (CeA), and in a key projection target of the CeA, the bed nucleus of the stria terminalis (BnST). While progress has been made in understanding the contributions and characteristics of CRF as a neuropeptide in rodent behavior, little attention has been committed to determine the properties and synaptic physiology of specific populations of CRF-expressing (CRF(+)) and non-expressing (CRF(-)) neurons in the CeA and BnST. Here, we fill this gap by electrophysiologically characterizing distinct neuronal subtypes in CeA and BnST. Crossing tdTomato or channelrhodopsin-2 (ChR2-YFP) reporter mice to those expressing Cre-recombinase under the CRF promoter allowed us to identify and manipulate CRF(+) and CRF(-) neurons in CeA and BnST, the two largest areas with fluorescently labeled neurons in these mice. We optogenetically activated CRF(+) neurons to elicit action potentials or synaptic responses in CRF(+) and CRF(-) neurons. We found that GABA is the predominant co-transmitter in CRF(+) neurons within the CeA and BnST. CRF(+) neurons are highly interconnected with CRF(-) neurons and to a lesser extent with CRF(+) neurons. CRF(+) and CRF(-) neurons differentially express tonic GABA currents. Chronic, unpredictable stress increase the amplitude of evoked IPSCs and connectivity between CRF(+) neurons, but not between CRF(+) and CRF(-) neurons in both regions. We propose that reciprocal inhibition of interconnected neurons controls CRF(+) output in these nuclei. PMID:27016019

  15. Central and peripheral contributions to dynamic changes in nucleus accumbens glucose induced by intravenous cocaine

    PubMed Central

    Wakabayashi, Ken T.; Kiyatkin, Eugene A.

    2015-01-01

    The pattern of neural, physiological and behavioral effects induced by cocaine is consistent with metabolic neural activation, yet direct attempts to evaluate central metabolic effects of this drug have produced controversial results. Here, we used enzyme-based glucose sensors coupled with high-speed amperometry in freely moving rats to examine how intravenous cocaine at a behaviorally active dose affects extracellular glucose levels in the nucleus accumbens (NAc), a critical structure within the motivation-reinforcement circuit. In drug-naive rats, cocaine induced a bimodal increase in glucose, with the first, ultra-fast phasic rise appearing during the injection (latency 6–8 s; ~50 μM or ~5% of baseline) followed by a larger, more prolonged tonic elevation (~100 μM or 10% of baseline, peak ~15 min). While the rapid, phasic component of the glucose response remained stable following subsequent cocaine injections, the tonic component progressively decreased. Cocaine-methiodide, cocaine's peripherally acting analog, induced an equally rapid and strong initial glucose rise, indicating cocaine's action on peripheral neural substrates as its cause. However, this analog did not induce increases in either locomotion or tonic glucose, suggesting direct central mediation of these cocaine effects. Under systemic pharmacological blockade of dopamine transmission, both phasic and tonic components of the cocaine-induced glucose response were only slightly reduced, suggesting a significant role of non-dopamine mechanisms in cocaine-induced accumbal glucose influx. Hence, intravenous cocaine induces rapid, strong inflow of glucose into NAc extracellular space by involving both peripheral and central, non-dopamine drug actions, thus preventing a possible deficit resulting from enhanced glucose use by brain cells. PMID:25729349

  16. A function for binaural integration in auditory grouping and segregation in the inferior colliculus.

    PubMed

    Nakamoto, Kyle T; Shackleton, Trevor M; Magezi, David A; Palmer, Alan R

    2015-03-15

    Responses of neurons to binaural, harmonic complex stimuli in urethane-anesthetized guinea pig inferior colliculus (IC) are reported. To assess the binaural integration of harmonicity cues for sound segregation and grouping, responses were measured to harmonic complexes with different fundamental frequencies presented to each ear. Simultaneously gated harmonic stimuli with fundamental frequencies of 125 Hz and 145 Hz were presented to the left and right ears, respectively, and recordings made from 96 neurons with characteristic frequencies >2 kHz in the central nucleus of the IC. Of these units, 70 responded continuously throughout the stimulus and were excited by the stimulus at the contralateral ear. The stimulus at the ipsilateral ear excited (EE: 14%; 10/70), inhibited (EI: 33%; 23/70), or had no significant effect (EO: 53%; 37/70), defined by the effect on firing rate. The neurons phase locked to the temporal envelope at each ear to varying degrees depending on signal level. Many of the cells (predominantly EO) were dominated by the response to the contralateral stimulus. Another group (predominantly EI) synchronized to the contralateral stimulus and were suppressed by the ipsilateral stimulus in a phasic manner. A third group synchronized to the stimuli at both ears (predominantly EE). Finally, a group only responded when the waveform peaks from each ear coincided. We conclude that these groups of neurons represent different "streams" of information but exhibit modifications of the response rather than encoding a feature of the stimulus, like pitch. PMID:25540219

  17. A function for binaural integration in auditory grouping and segregation in the inferior colliculus

    PubMed Central

    Shackleton, Trevor M.; Magezi, David A.; Palmer, Alan R.

    2014-01-01

    Responses of neurons to binaural, harmonic complex stimuli in urethane-anesthetized guinea pig inferior colliculus (IC) are reported. To assess the binaural integration of harmonicity cues for sound segregation and grouping, responses were measured to harmonic complexes with different fundamental frequencies presented to each ear. Simultaneously gated harmonic stimuli with fundamental frequencies of 125 Hz and 145 Hz were presented to the left and right ears, respectively, and recordings made from 96 neurons with characteristic frequencies >2 kHz in the central nucleus of the IC. Of these units, 70 responded continuously throughout the stimulus and were excited by the stimulus at the contralateral ear. The stimulus at the ipsilateral ear excited (EE: 14%; 10/70), inhibited (EI: 33%; 23/70), or had no significant effect (EO: 53%; 37/70), defined by the effect on firing rate. The neurons phase locked to the temporal envelope at each ear to varying degrees depending on signal level. Many of the cells (predominantly EO) were dominated by the response to the contralateral stimulus. Another group (predominantly EI) synchronized to the contralateral stimulus and were suppressed by the ipsilateral stimulus in a phasic manner. A third group synchronized to the stimuli at both ears (predominantly EE). Finally, a group only responded when the waveform peaks from each ear coincided. We conclude that these groups of neurons represent different “streams” of information but exhibit modifications of the response rather than encoding a feature of the stimulus, like pitch. PMID:25540219

  18. Spread of cochlear excitation during stimulation with pulsed infrared radiation: inferior colliculus measurements

    NASA Astrophysics Data System (ADS)

    Richter, C.-P.; Rajguru, S. M.; Matic, A. I.; Moreno, E. L.; Fishman, A. J.; Robinson, A. M.; Suh, E.; Walsh, J. T., Jr.

    2011-10-01

    Infrared neural stimulation (INS) has received considerable attention over the last few years. It provides an alternative method to artificially stimulate neurons without electrical current or the introduction of exogenous chromophores. One of the primary benefits of INS could be the improved spatial selectivity when compared with electrical stimulation. In the present study, we have evaluated the spatial selectivity of INS in the acutely damaged cochlea of guinea pigs and compared it to stimulation with acoustic tone pips in normal-hearing animals. The radiation was delivered via a 200 µm diameter optical fiber, which was inserted through a cochleostomy into the scala tympani of the basal cochlear turn. The stimulated section along the cochlear spiral ganglion was estimated from the neural responses recorded from the central nucleus of the inferior colliculus (ICC). ICC responses were recorded in response to cochlear INS using a multichannel penetrating electrode array. Spatial tuning curves (STCs) were constructed from the responses. For INS, approximately 55% of the activation profiles showed a single maximum, ~22% had two maxima and ~13% had multiple maxima. The remaining 10% of the profiles occurred at the limits of the electrode array and could not be classified. The majority of ICC STCs indicated that the spread of activation evoked by optical stimuli is comparable to that produced by acoustic tone pips.

  19. Whisker-related afferents in superior colliculus.

    PubMed

    Castro-Alamancos, Manuel A; Favero, Morgana

    2016-05-01

    Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in the intermediate layers of the superior colliculus integrate trigeminotectal afferents from trigeminal complex and corticotectal afferents from barrel cortex. Using histological methods in mice, we found that trigeminotectal and corticotectal synapses overlap somewhat as they innervate the lower and upper portions of the intermediate granular layer, respectively. Using electrophysiological recordings and optogenetics in anesthetized mice in vivo, we showed that, similar to rats, whisker deflections produce two successive responses that are driven by trigeminotectal and corticotectal afferents. We then employed in vivo and slice experiments to characterize the response properties of these afferents. In vivo, corticotectal responses triggered by electrical stimulation of the barrel cortex evoke activity in the superior colliculus that increases with stimulus intensity and depresses with increasing frequency. In slices from adult mice, optogenetic activation of channelrhodopsin-expressing trigeminotectal and corticotectal fibers revealed that cells in the intermediate layers receive more efficacious trigeminotectal, than corticotectal, synaptic inputs. Moreover, the efficacy of trigeminotectal inputs depresses more strongly with increasing frequency than that of corticotectal inputs. The intermediate layers of superior colliculus appear to be tuned to process strong but infrequent trigeminal inputs and weak but more persistent cortical inputs, which explains features of sensory responsiveness, such as the robust rapid sensory adaptation of whisker responses in the superior colliculus. PMID:26864754

  20. Exploring the Superior Colliculus In Vitro

    PubMed Central

    2009-01-01

    The superior colliculus plays an important role in the translation of sensory signals that encode the location of objects in space into motor signals that encode vectors of the shifts in gaze direction called saccades. Since the late 1990s, our two laboratories have been applying whole cell patch-clamp techniques to in vitro slice preparations of rodent superior colliculus to analyze the structure and function of its circuitry at the cellular level. This review describes the results of these experiments and discusses their contributions to our understanding of the mechanisms responsible for sensorimotor integration in the superior colliculus. The experiments analyze vertical interactions between its superficial visuosensory and intermediate premotor layers and propose how they might contribute to express saccades and to saccadic suppression. They also compare and contrast the circuitry within each of these layers and propose how this circuitry might contribute to the selection of the targets for saccades and to the build-up of the premotor commands that precede saccades. Experiments also explore in vitro the roles of extrinsic inputs to the superior colliculus, including cholinergic inputs from the parabigeminal and parabrachial nuclei and GABAergic inputs from the substantia nigra pars reticulata, in modulating the activity of the collicular circuitry. The results extend and clarify our understanding of the multiple roles the superior colliculus plays in sensorimotor integration. PMID:19710376

  1. Corticotropin-releasing factor within the central nucleus of the amygdala and the nucleus accumbens shell mediates the negative affective state of nicotine withdrawal in rats

    PubMed Central

    Marcinkiewcz, Catherine A.; Prado, Melissa M.; Isaac, Shani K.; Marshall, Alex; Rylkova, Daria; Bruijnzeel, Adrie W.

    2008-01-01

    Tobacco addiction is a chronic disorder that is characterized by a negative affective state upon smoking cessation and relapse after periods of abstinence. Previous research has shown that an increased central release of corticotropin-releasing factor (CRF) at least partly mediates the deficit in brain reward function associated with nicotine withdrawal in rats. The aim of these studies was to investigate the role of CRF in the central nucleus of the amygdala (CeA), the lateral bed nucleus of the stria terminalis (BNST), and the nucleus accumbens shell (Nacc shell) in the deficit in brain reward function associated with precipitated nicotine withdrawal. The intracranial self-stimulation procedure was used to assess the negative affective aspects of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. In all experiments, the nicotinic receptor antagonist mecamylamine (3 mg/kg) elevated the brain reward thresholds of the nicotine dependent rats (9 mg/kg/day of nicotine salt) and did not affect the brain reward thresholds of the saline-treated control rats. The administration of the nonspecific CRF1/2 receptor antagonist D-Phe CRF(12–41) into the CeA and the Nacc shell prevented the mecamylamine-induced elevations in brain reward thresholds in the nicotine dependent rats. Blockade of CRF1/2 receptors in the lateral BNST did not prevent the mecamylamine-induced elevations in brain reward thresholds in the nicotine dependent rats. These studies indicate that the negative emotional state associated with precipitated nicotine withdrawal is at least partly mediated by an increased release of CRF in the CeA and Nacc shell. PMID:19145226

  2. Synaptic and network consequences of monosynaptic nociceptive inputs of parabrachial nucleus origin in the central amygdala

    PubMed Central

    Sugimura, Yae K.; Takahashi, Yukari; Watabe, Ayako M.

    2016-01-01

    A large majority of neurons in the superficial layer of the dorsal horn projects to the lateral parabrachial nucleus (LPB). LPB neurons then project to the capsular part of the central amygdala (CeA; CeC), a key structure underlying the nociception-emotion link. LPB-CeC synaptic transmission is enhanced in various pain models by using electrical stimulation of putative fibers of LPB origin in brain slices. However, this approach has limitations for examining direct monosynaptic connections devoid of directly stimulating fibers from other structures and local GABAergic neurons. To overcome these limitations, we infected the LPB of rats with an adeno-associated virus vector expressing channelrhodopsin-2 and prepared coronal and horizontal brain slices containing the amygdala. We found that blue light stimulation resulted in monosynaptic excitatory postsynaptic currents (EPSCs), with very small latency fluctuations, followed by a large polysynaptic inhibitory postsynaptic current in CeC neurons, regardless of the firing pattern type. Intraplantar formalin injection at 24 h before slice preparation significantly increased EPSC amplitude in late firing-type CeC neurons. These results indicate that direct monosynaptic glutamatergic inputs from the LPB not only excite CeC neurons but also regulate CeA network signaling through robust feed-forward inhibition, which is under plastic modulation in response to persistent inflammatory pain. PMID:26888105

  3. Central amygdalar nucleus treated with orexin neuropeptides evoke differing feeding and grooming responses in the hamster.

    PubMed

    Alò, Raffaella; Avolio, Ennio; Mele, Maria; Di Vito, Anna; Canonaco, Marcello

    2015-04-15

    Interaction of the orexinergic (ORXergic) neuronal system with the excitatory (glutamate, l-Glu) or the inhibitory (GABA) neurosignaling complexes evokes major homeostatic physiological events. In this study, effects of the two ORXergic neuropeptides (ORX-A/B) on their receptor (ORX-2R) expression changes were correlated to feeding and grooming actions of the hibernating hamster (Mesocricetus auratus). Infusion of the central amygdala nucleus (CeA) with ORX-A caused hamsters to consume notable quantities of food, while ORX-B accounted for a moderate increase. Interestingly the latter neuropeptide was responsible for greater frequencies of grooming with respect to both controls and the hamsters treated with ORX-A. These distinct behavioral changes turned out to be even greater in the presence of l-Glu agonist (NMDA) while the α1 GABAA receptor agonist (zolpidem, Zol) greatly reduced ORX-A-dependent feeding bouts. Moreover, ORX-A+NMDA mainly promoted greater ORX-2R expression levels with respect to ORX-A-treated hamsters while ORX-B+Zol was instead largely responsible for a down-regulatory trend. Overall, these features point to CeA ORX-2R sites as key sensory limbic elements capable of regulating eating and grooming responses, which may provide useful insights regarding the type of molecular mechanism(s) operating during feeding bouts. PMID:25732800

  4. Individual Differences in Amphetamine Self-Administration: The Role of the Central Nucleus of the Amygdala

    PubMed Central

    Cain, Mary E.; Denehy, Emily R.; Bardo, Michael T.

    2009-01-01

    Rats categorized as high responder (HR) based on their activity in an inescapable novel environment self-administer more amphetamine than low responder (LR) rats. The current study examined if the central nucleus of the amygdala (ACe) contributes to the elevated response for amphetamine in HR rats. Male Sprague-Dawley rats were classified as HR and LR rats based on their activity in inescapable novelty and novelty place preference, and then were trained to self-administer amphetamine (0.1 mg/kg/infusion). Once stable responding was achieved, rats received microinfusions of the GABAA agonist muscimol (0.5 μg/0.5 μl) or phosphate buffered saline into the ACe immediately prior to self-administration of amphetamine (0.1, 0.03, 0.01, or 0.001 mg/kg/infusion) or saline. An additional group of rats was trained to lever press for sucrose rather than amphetamine. Based on the inescapable novelty test, HR rats self-administered more amphetamine than LR rats at the 0.03 and 0.01 mg/kg/infusion unit doses; there were no significant individual differences in amphetamine self-administration based on the novelty place preference test. Inactivation of the ACe with muscimol decreased self-administration at the 0.03 and 0.01 mg/kg/infusion unit doses in HR rats, but had no effect on LR rats. ACe inactivation had no reliable effect on inactive lever responding and appeared to be region-specific based on anatomical controls. In addition, while inactivation of the ACe decreased responding for sucrose, inactivation did not differentially affect HR and LR rats. These results suggest that the ACe contributes to the elevated rate of amphetamine self-administration in HR rats. PMID:17568395

  5. Lesions of the central nucleus of the amygdala decrease taste threshold for sodium chloride in rats.

    PubMed

    Li, Jinrong; Yan, Jianqun; Chen, Ke; Lu, Bo; Wang, Qian; Yan, Wei; Zhao, Xiaolin

    2012-10-01

    Previous studies reported that NaCl intake was down-regulated in rats with bilateral lesions of the central nucleus of the amygdala (CeA). In line with the evidence from anatomical and physiological studies, such an inhibition could be the result of altered taste threshold for NaCl, one of the important factors in assessing taste functions. To assess the effect of CeA on the taste threshold for NaCl, a conditioned taste aversion (CTA) to a suprathreshold concentration of NaCl (0.1M) in rats with bilateral lesions of CeA or sham lesions was first established. And then, two-bottle choice tests between water and a series of concentrations of NaCl were conducted. The taste threshold for NaCl is defined as the lowest concentration at which there is a reliable difference scores between conditioned and control subjects. Rats with CeA lesions acquired a taste aversion for 0.1M NaCl when it was paired with LiCl and still retained the aversion after the two-bottle choice test. The results of the two-bottle choice test showed that the taste threshold for NaCl was 0.0006M in rats with CeA lesions, whereas in rats with sham lesions the threshold was 0.005M, which was identical to that of normal rats. The conditioned results confirm the claim that CeA is not essential in the profile of conditioned taste aversion. Our findings demonstrate that lesions of the CeA increased the sensitivity to NaCl taste in rats, indicating that the CeA may be involved in encoding the intensity of salty gustation elicited by NaCl. PMID:22796484

  6. Positive reinforcing effect of oxytocin microinjection in the rat central nucleus of amygdala.

    PubMed

    László, K; Kovács, A; Zagoracz, O; Ollmann, T; Péczely, L; Kertes, E; Lacy, D G; Lénárd, L

    2016-01-01

    Neuropeptide oxytocin (OT) receives increasing attention since, it plays a role in various behaviors including anxiety, drug addiction, learning, social recognition, empathy, pair bonding and decreased aggression. The central nucleus of the amygdala (CeA), part of the limbic system, plays an important role in learning, memory, anxiety and reinforcing mechanisms. CeA was shown to be rich in OT-receptors (OTR). The aim of our study was to examine the possible effects of OT and OTR antagonist in the CeA on reinforcement using the conditioned place preference test and on anxiety using the elevated plus maze test. Male Wistar rats were microinjected bilaterally with 10 ng OT or 100 ng OT (Sigma: O6379, injected in volume of 0.4μl) or 10ng OTR antagonist (Sigma: L-2540) alone, or OTR antagonist 15 min prior 10 ng OT treatment or vehicle solution into the CeA. Rats receiving 10 ng OT spent significantly more time in the treatment quadrant during the test session, while 100 ng OT treatment produced no effect. Prior treatment with the non-peptide OTR antagonist blocked the effects of OT. The antagonist in itself did not influence the place preference. The elevated plus maze test revealed that 10 ng OT significantly increased the time spent in the open arms. OTR antagonist pre-treatment could inhibit this effect and the antagonist in itself did not affect the time spent in the open arms. Our results show that in the rat CeA OT has dose-dependent, positive reinforcing and anxiolytic effects, via OTR demonstrated by the blocking effects of selective OTR antagonist. PMID:26386304

  7. Genipin attenuates lipopolysaccharide-induced persistent changes of emotional behaviors and neural activation in the hypothalamic paraventricular nucleus and the central amygdala nucleus.

    PubMed

    Araki, Ryota; Hiraki, Yosuke; Yabe, Takeshi

    2014-10-15

    Sickness behavior is a series of behavioral and psychological changes that develop in inflammatory disease, including infections and cancers. Administration of the bacterial endotoxin lipopolysaccharide (LPS) induces sickness behavior in rodents. Genipin, an aglycon derived from an iridoid glycoside geniposide extracted from the fruit of Gardenia jasminoides, has anti-inflammatory and antidepressant activities. However, the effects of genipin on inflammation-induced changes in emotional behaviors are unknown. In this study, we examined the effects of genipin on LPS-induced inflammation in BV-2 cells and sickness behavior in mice. Pretreatment with genipin inhibited LPS-induced increases in NO production and reduced the mRNA levels of inflammation-related genes (iNOS, COX-2, IL-1β and IL-6) in BV-2 cells. Oral administration of genipin ameliorated LPS-induced depressive-like behavior in the forced swim test and social behavior deficits 24h after LPS administration in mice. LPS-induced expression of mRNAs for inflammation-related genes and the number of c-fos immunopositive cells decreased in the paraventricular nucleus (PVN) of the hypothalamus and the central nucleus of the amygdala (CeA), suggesting that genipin attenuates LPS-induced changes of emotional behaviors through inhibition of neural activation and inflammatory responses in the PVN and CeA. These novel pharmacological effects of genipin may be useful for treatment of patients with sickness behavior. PMID:25084220

  8. Dopaminergic Input to the Inferior Colliculus in Mice.

    PubMed

    Nevue, Alexander A; Elde, Cameron J; Perkel, David J; Portfors, Christine V

    2015-01-01

    The response of sensory neurons to stimuli can be modulated by a variety of factors including attention, emotion, behavioral context, and disorders involving neuromodulatory systems. For example, patients with Parkinson's disease (PD) have disordered speech processing, suggesting that dopamine alters normal representation of these salient sounds. Understanding the mechanisms by which dopamine modulates auditory processing is thus an important goal. The principal auditory midbrain nucleus, the inferior colliculus (IC), is a likely location for dopaminergic modulation of auditory processing because it contains dopamine receptors and nerve terminals immunoreactive for tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis. However, the sources of dopaminergic input to the IC are unknown. In this study, we iontophoretically injected a retrograde tracer into the IC of mice and then stained the tissue for TH. We also immunostained for dopamine beta-hydroxylase (DBH), an enzyme critical for the conversion of dopamine to norepinephrine, to differentiate between dopaminergic and noradrenergic inputs. Retrogradely labeled neurons that were positive for TH were seen bilaterally, with strong ipsilateral dominance, in the subparafascicular thalamic nucleus (SPF). All retrogradely labeled neurons that we observed in other brain regions were TH-negative. Projections from the SPF were confirmed using an anterograde tracer, revealing TH-positive and DBH-negative anterogradely labeled fibers and terminals in the IC. While the functional role of this dopaminergic input to the IC is not yet known, it provides a potential mechanism for context dependent modulation of auditory processing. PMID:26834578

  9. Dopaminergic Input to the Inferior Colliculus in Mice

    PubMed Central

    Nevue, Alexander A.; Elde, Cameron J.; Perkel, David J.; Portfors, Christine V.

    2016-01-01

    The response of sensory neurons to stimuli can be modulated by a variety of factors including attention, emotion, behavioral context, and disorders involving neuromodulatory systems. For example, patients with Parkinson’s disease (PD) have disordered speech processing, suggesting that dopamine alters normal representation of these salient sounds. Understanding the mechanisms by which dopamine modulates auditory processing is thus an important goal. The principal auditory midbrain nucleus, the inferior colliculus (IC), is a likely location for dopaminergic modulation of auditory processing because it contains dopamine receptors and nerve terminals immunoreactive for tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis. However, the sources of dopaminergic input to the IC are unknown. In this study, we iontophoretically injected a retrograde tracer into the IC of mice and then stained the tissue for TH. We also immunostained for dopamine beta-hydroxylase (DBH), an enzyme critical for the conversion of dopamine to norepinephrine, to differentiate between dopaminergic and noradrenergic inputs. Retrogradely labeled neurons that were positive for TH were seen bilaterally, with strong ipsilateral dominance, in the subparafascicular thalamic nucleus (SPF). All retrogradely labeled neurons that we observed in other brain regions were TH-negative. Projections from the SPF were confirmed using an anterograde tracer, revealing TH-positive and DBH-negative anterogradely labeled fibers and terminals in the IC. While the functional role of this dopaminergic input to the IC is not yet known, it provides a potential mechanism for context dependent modulation of auditory processing. PMID:26834578

  10. The central vestibular complex in dolphins and humans: functional implications of Deiters' nucleus.

    PubMed

    Kern, A; Seidel, K; Oelschläger, H H A

    2009-01-01

    Toothed whales (Odontocetes; e.g., dolphins) are well-known for efficient underwater locomotion and for their acrobatic capabilities. Nevertheless, in relation to other mammals including the human and with respect to body size, their vestibular apparatus is reduced, particularly the semicircular canals. Concomitantly, the vestibular nerve and most of the vestibular nuclei are thin and small, respectively, in comparison with those in terrestrial mammals. In contrast, the lateral (Deiters') vestibular nucleus is comparatively well developed in both coastal and pelagic dolphins. In the La Plata dolphin (Pontoporia blainvillei) and the Common dolphin (Delphinus delphis), all of the vestibular nuclei are present and their topographic relations are similar to those in humans. Quantitative analysis, however, revealed that in the dolphin most of the nuclei (superior, medial, descending nucleus) are minute both in absolute and relative terms. Here, the only exception is the lateral vestibular nucleus, which is of comparable size in humans and Pontoporia and decidedly more voluminous in Delphinus. While the small size of the majority of the dolphin's vestibular nuclei correlates well with miniaturization of the semicircular canals, the size of Deiters' nucleus seems to support its relative independence from the vestibular system and a close functional relationship with the cerebellum. In comparison with findings in humans and other terrestrial mammals, both of these aspects seem to be related to the physical conditions of aquatic life and locomotion in three dimensions. PMID:19390175

  11. Effects of neonatal enucleation on the functional organization of the superior colliculus in the golden hamster.

    PubMed Central

    Rhoades, R W

    1980-01-01

    1. The responses of visual, auditory and somatosensory superior collicular neurones were investigated using extracellular single unit recording techniques in hamsters which were subjected to the removal of one eye on the day of birth. 2. Neonatal enucleation resulted in a marked increase in the region of the colliculus from which visual neurones activated by stimulation of the ipsilateral eye could be recorded. In most cases the visuotopic representation in the colliculus ipsilateral to the remaining eye mirrored that observed in the contralateral tectum along both the rostrocaudal and mediolateral axes: in both colliculi temporal retina projected rostrally and inferior retina medially. In some animals, however, there appeared to be a dual mapping of the remaining eye onto the ipsilateral tectum. In these hamsters the central portion of the visual field was represented twice along the rostrocaudal axis of colliculus. 3. No changes in the topography of the somatosensory and auditory representations in the tectum were observed following neonatal enucleation. 4. The laminar distribution of visual neurones in the ipsilateral colliculus was markedly altered in the neonatally enucleated hamsters. Very few exclusively visual units were encountered in the layers ventral to the stratum opticum and almost all of the visual cells recorded in the ipsilateral colliculus were isolated within 150 microM of the tectal surface. 5. In the posterior half of the ipsilateral tectum a large number of extravisually responsive cells were encountered in the stratum griseum superficiale and stratum opticum. This was not the case in the colliculus contralateral to the remaining eye, nor has it ever been observed in normal hamsters. 6. Recordings from animals subjected to both neonatal enucleation and acute bilateral removal of somatosensory and auditory cortex indicated that the projections from these areas to the colliculus were not essential to the observed changes in laminar organization

  12. Frequency response areas in the inferior colliculus: nonlinearity and binaural interaction

    PubMed Central

    Yu, Jane J.; Young, Eric D.

    2013-01-01

    The tuning, binaural properties, and encoding characteristics of neurons in the central nucleus of the inferior colliculus (CNIC) were investigated to shed light on nonlinearities in the responses of these neurons. Results were analyzed for three types of neurons (I, O, and V) in the CNIC of decerebrate cats. Rate responses to binaural stimuli were characterized using a 1st- plus 2nd-order spectral integration model. Parameters of the model were derived using broadband stimuli with random spectral shapes (RSS). This method revealed four characteristics of CNIC neurons: (1) Tuning curves derived from broadband stimuli have fixed (i. e., level tolerant) bandwidths across a 50–60 dB range of sound levels; (2) 1st-order contralateral weights (particularly for type I and O neurons) were usually larger in magnitude than corresponding ipsilateral weights; (3) contralateral weights were more important than ipsilateral weights when using the model to predict responses to untrained noise stimuli; and (4) 2nd-order weight functions demonstrate frequency selectivity different from that of 1st-order weight functions. Furthermore, while the inclusion of 2nd-order terms in the model usually improved response predictions related to untrained RSS stimuli, they had limited impact on predictions related to other forms of filtered broadband noise [e. g., virtual-space stimuli (VS)]. The accuracy of the predictions varied considerably by response type. Predictions were most accurate for I neurons, and less accurate for O and V neurons, except at the lowest stimulus levels. These differences in prediction performance support the idea that type I, O, and V neurons encode different aspects of the stimulus: while type I neurons are most capable of producing linear representations of spectral shape, type O and V neurons may encode spectral features or temporal stimulus properties in a manner not easily explained with the low-order model. Supported by NIH grant DC00115. PMID:23675323

  13. Differences in the strength of cortical and brainstem inputs to SSA and non-SSA neurons in the inferior colliculus

    PubMed Central

    Ayala, Yaneri A.; Udeh, Adanna; Dutta, Kelsey; Bishop, Deborah; Malmierca, Manuel S.; Oliver, Douglas L.

    2015-01-01

    In an ever changing auditory scene, change detection is an ongoing task performed by the auditory brain. Neurons in the midbrain and auditory cortex that exhibit stimulus-specific adaptation (SSA) may contribute to this process. Those neurons adapt to frequent sounds while retaining their excitability to rare sounds. Here, we test whether neurons exhibiting SSA and those without are part of the same networks in the inferior colliculus (IC). We recorded the responses to frequent and rare sounds and then marked the sites of these neurons with a retrograde tracer to correlate the source of projections with the physiological response. SSA neurons were confined to the non-lemniscal subdivisions and exhibited broad receptive fields, while the non-SSA were confined to the central nucleus and displayed narrow receptive fields. SSA neurons receive strong inputs from auditory cortical areas and very poor or even absent projections from the brainstem nuclei. On the contrary, the major sources of inputs to the neurons that lacked SSA were from the brainstem nuclei. These findings demonstrate that auditory cortical inputs are biased in favor of IC synaptic domains that are populated by SSA neurons enabling them to compare top-down signals with incoming sensory information from lower areas. PMID:25993334

  14. Deep brain stimulation of the inferior colliculus: a possible animal model to study paradoxical kinesia observed in some parkinsonian patients?

    PubMed

    Melo-Thomas, Liana; Thomas, Uwe

    2015-02-15

    The inferior colliculus (IC) plays an important role in the normal processing of the acoustic message and is also involved in the filtering of acoustic stimuli of aversive nature. The neural substrate of the IC can also influence haloperidol-induced catalepsy. Considering that (i) paradoxical kinesia, observed in some parkinsonian patients, seems to be dependent of their emotional state and (ii) deep brain stimulation (DBS) represents an alternative therapeutic route for the relief of parkinsonian symptoms, the present study investigated the consequence of DBS at the IC on the catalepsy induced by haloperidol in rats. Additionally, we investigated if DBS of the IC can elicit motor responses in anesthetized rats and whether DBS elicits distinct neural firing patterns of activity at the dorsal cortex (DCIC) or central nucleus (CNIC) of the IC. A significant reduction of the catalepsy response was seen in rats previously given haloperidol and receiving DBS at the IC. In addition, electrical stimulation to the ventral part of the CNIC induced immediate motor responses in anesthetized rats. The neuronal spontaneous activity was higher at the ventral part of the CNIC than the dorsal part. DBS to the ventral part but not to the dorsal part of the CNIC increased the spike rate at neurons a few hundred microns away from the stimulation site. It is possible that the IC plays a role in the sensorimotor gating activated by emotional stimuli, and that DBS at the IC can be a promising new animal model to study paradoxical kinesia in rats. PMID:25446814

  15. Central connectivity of the chorda tympani afferent terminals in the rat rostral nucleus of the solitary tract.

    PubMed

    Park, Sook Kyung; Lee, Dae Seop; Bae, Jin Young; Bae, Yong Chul

    2016-03-01

    The rostral nucleus of the solitary tract (rNST) receives gustatory input via chorda tympani (CT) afferents from the anterior two-thirds of the tongue and transmits it to higher brain regions. To help understand how the gustatory information is processed at the 1st relay nucleus of the brain stem, we investigated the central connectivity of the CT afferent terminals in the central subdivision of the rat rNST through retrograde labeling with horseradish peroxidase, immunogold staining for GABA, glycine, and glutamate, and quantitative ultrastructural analysis. Most CT afferents were small myelinated fibers (<5 µm(2) in cross-sectional area) and made simple synaptic arrangements with 1-2 postsynaptic dendrites. It suggests that the gustatory signal is relayed to a specific group of neurons with a small degree of synaptic divergence. The volume of the identified synaptic boutons was positively correlated with their mitochondrial volume and active zone area, and also with the number of their postsynaptic dendrites. One-fourth of the boutons received synapses from GABA-immunopositive presynaptic profiles, 27 % of which were also glycine-immunopositive. These results suggest that the gustatory information mediated by CT afferents to the rNST is processed in a simple and specific manner. They also suggest that the minority of CT afferents are presynaptically modulated by GABA- and/or glycine-mediated mechanism. PMID:25503820

  16. Direction Selectivity Mediated by Adaptation in the Owl's Inferior Colliculus

    PubMed Central

    Peña, José Luis

    2013-01-01

    Motion direction is a crucial cue for predicting future states in natural scenes. In the auditory system, the mechanisms that confer direction selectivity to neurons are not well understood. Neither is it known whether sound motion is encoded independently of stationary sound location. Here we investigated these questions in neurons of the owl's external nucleus of the inferior colliculus, where auditory space is represented in a map. Using a high-density speaker array, we show that the preferred direction and the degree of direction selectivity can be predicted by response adaptation to sounds moving over asymmetric spatial receptive fields. At the population level, we found that preference for sounds moving toward frontal space increased with eccentricity in spatial tuning. This distribution was consistent with larger receptive-field asymmetry in neurons tuned to more peripheral auditory space. A model of suppression based on spatiotemporal summation predicted the observations. Thus, response adaptation and receptive-field shape can explain direction selectivity to acoustic motion and an orderly distribution of preferred direction. PMID:24305813

  17. Optogenetic cholinergic modulation of the mouse superior colliculus in vivo

    PubMed Central

    Thompson, John A.; Felsen, Gidon

    2015-01-01

    The superior colliculus (SC) plays a critical role in orienting movements, in part by integrating modulatory influences on the sensorimotor transformations it performs. Many species exhibit a robust brain stem cholinergic projection to the intermediate and deep layers of the SC arising mainly from the pedunculopontine tegmental nucleus (PPTg), which may serve to modulate SC function. However, the physiological effects of this input have not been examined in vivo, preventing an understanding of its functional role. Given the data from slice experiments, cholinergic input may have a net excitatory effect on the SC. Alternatively, the input could have mixed effects, via activation of inhibitory neurons within or upstream of the SC. Distinguishing between these possibilities requires in vivo experiments in which endogenous cholinergic input is directly manipulated. Here we used anatomical and optogenetic techniques to identify and selectively activate brain stem cholinergic terminals entering the intermediate and deep layers of the awake mouse SC and recorded SC neuronal responses. We first quantified the pattern of the cholinergic input to the mouse SC, finding that it was predominantly localized to the intermediate and deep layers. We then found that optogenetic stimulation of cholinergic terminals in the SC significantly increased the activity of a subpopulation of SC neurons. Interestingly, cholinergic input had a broad range of effects on the magnitude and timing of SC responses, perhaps reflecting both monosynaptic and polysynaptic innervation. These findings begin to elucidate the functional role of this cholinergic projection in modulating the processing underlying sensorimotor transformations in the SC. PMID:26019317

  18. Motor Functions of the Superior Colliculus

    PubMed Central

    Gandhi, Neeraj J.; Katnani, Husam A.

    2013-01-01

    The mammalian superior colliculus (SC) and its nonmammalian homolog, the optic tectum, constitute a major node in processing sensory information, incorporating cognitive factors, and issuing motor commands. The resulting action—to orient toward or away from a stimulus—can be accomplished as an integrated movement across oculomotor, cephalomotor, and skeletomotor effectors. The SC also participates in preserving fixation during intersaccadic intervals. This review highlights the repertoire of movements attributed to SC function and analyzes the significance of results obtained from causality-based experiments (microstimulation and inactivation). The mechanisms potentially used to decode the population activity in the SC into an appropriate movement command are also discussed. PMID:21456962

  19. NMDA and non-NMDA glutamate receptors in auditory transmission in the barn owl inferior colliculus.

    PubMed

    Feldman, D E; Knudsen, E I

    1994-10-01

    The pharmacology of auditory responses in the inferior colliculus (IC) of the barn owl was investigated by iontophoresis of excitatory amino acid receptor antagonists into two different functional subdivisions of the IC, the external nucleus (ICx) and the lateral shell of the central nucleus (lateral shell), both of which carry out important computations in the processing of auditory spatial information. Combined application of the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (AP5) and the non-NMDA receptor antagonist 6-cyano-5-nitroquinoxaline-2,3-dione (CNQX) significantly reduced auditory-evoked spikes at all sites in these two subdivisions, and completely eliminated responses at many locations. This suggests that excitatory amino acid receptors mediate the bulk, if not all, of auditory responses in the ICx and lateral shell. NMDA and non-NMDA receptors contributed differently to auditory responses in the two subdivisions. In the ICx, AP5 significantly reduced the number of auditory-evoked spikes at every site tested. On average, AP5 eliminated 55% of auditory-evoked spikes at multiunit sites and 64% at single-unit sites in this structure. In contrast, in the lateral shell, AP5 significantly reduced responses at less than half the sites tested, and, on average, AP5 eliminated only 19% of spikes at multiunit sites and 25% at single-unit sites. When the magnitude of response blockade produced by AP5 at individual multiunit sites was normalized to adjust for site-to-site differences in the efficacy of iontophoresed AP5 and CNQX, AP5 blockade was still significantly greater in the ICx than the lateral shell. CNQX application strongly reduced responses in both subdivisions. These data suggest that NMDA receptor currents make a major contribution to auditory responses in the ICx, while they make only a small contribution to auditory responses in the lateral shell. Non-NMDA receptor currents, on the other hand, contribute to auditory responses in both

  20. NMDA Receptor Agonism and Antagonism within the Amygdaloid Central Nucleus Suppresses Pain Affect: Differential Contribution of the Ventrolateral Periaqueductal Gray

    PubMed Central

    Spuz, Catherine A.; Tomaszycki, Michelle L.; Borszcz, George S.

    2015-01-01

    The amygdala contributes to the generation of pain affect and the amygdaloid central nucleus (CeA) receives nociceptive input that is mediated by glutamatergic neurotransmission. The present study compared the contribution of N-methyl-D-aspartate (NMDA) receptor agonism and antagonism in CeA to generation of the affective response of rats to an acute noxious stimulus. Vocalizations that occur following a brief tail shock (vocalization afterdischarges) are a validated rodent model of pain affect, and were preferentially suppressed, in a dose dependent manner, by bilateral injection into CeA of NMDA (.1 µg, .25 µg, .5 µg, or 1 µg/side), or the NMDA receptor antagonist D-2-amino-5-phosphonovalerate (AP5, 1 µg, 2 µg, or 4 µg/side). Vocalizations that occur during tail shock were suppressed to a lesser degree, whereas, spinal motor reflexes (tail flick and hind limb movements) were unaffected by injection of NMDA or AP5 into CeA. Injection of NMDA, but not AP5, into CeA increased c-Fos immunoreactivity in the ventrolateral periaqueductal gray (vlPAG), and unilateral injection of the µ-opiate receptor antagonist H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP, 0.25 µg) into vlPAG prevented the antinociception generated by injection of NMDA into CeA. These findings demonstrate that although NMDA receptor agonism and antagonism in CeA produce similar suppression of pain behaviors they do so via different neurobiological mechanisms. Perspective The amygdala contributes to production of the emotional dimension of pain. NMDA receptor agonism and antagonism within the central nucleus of the amygdala suppressed rats’ emotional response to acute painful stimulation. Understanding the neurobiology underlying emotional responses to pain will provide insights into new treatments for pain and its associated affective disorders. PMID:25261341

  1. Accessing the tonotopic organization of the ventral cochlear nucleus by intranuclear microstimulation.

    PubMed

    McCreery, D B; Shannon, R V; Moore, J K; Chatterjee, M

    1998-12-01

    This study is part of a program to develop an auditory prosthesis for the profoundly deaf, based on multichannel microstimulation in the cochlear nucleus. The functionality of such a device is dependent on its ability to access the tonotopic axis of the human ventral cochlear nucleus in an orderly fashion. In these studies, we utilized the homologies between the human and feline ventral cochlear nuclei and the known tonotopic organization of the central nucleus of the inferior colliculus (IC). In anesthetized cats, stimuli were delivered to three or four locations along the dorsal-to-ventral axis of the posteroventral cochlear nucleus (PVCN), and for each stimulus location, we recorded the multiunit neuronal activity and the field potentials at 20 or more locations along the dorsolateral-ventromedial (tonotopic) axis of the IC. The current source-sink density (CSD), which delimits regions of neuronal activity, was computed from the sequence of field potentials recorded along this axis. The multiunit activity and the CSD analysis both showed that the tonotopic organization of the PVCN can be accessed in an orderly manner by intranuclear microstimulation in several regions of the PVCN, using the range of stimulus pulse amplitudes that have been shown in previous studies to be noninjurious during prolonged intranuclear microstimulation via chronically implanted microelectrodes. We discuss the applicability of these findings to the design of clinical auditory prostheses for implantation into the human cochlear nucleus. PMID:9865886

  2. Binocular interaction in the cat's superior colliculus.

    PubMed Central

    Berman, N; Blakemore, C; Cynader, M

    1975-01-01

    1. Binocularly driven neurones with small receptive fields near the area centralis were recorded in the cat's superior colliculus. 2. Binocular interaction was tested by stimulating both eyes simultaneously with a single moving stimulus at various retinal disparities. 3. Collicular cells in general showed strong summation or even facilitation when the images of the stimulus were in exact correspondence on the receptive fields, sometimes with occlusion when they were out of register. The range of retinal disparity over which there was additive interaction could be as little as 1 or 2 deg, almost as narrow as for the most precisely tuned neurones in the visual cortex. Even cells with large receptive fields sometimes showed a narrow range of binocular interaction. 4. Non-directional cells generally exhibited weaker summation and broader disparity selectivity than did direction-selective cells. 5. Some neurones with virtually no response to a stimulus in one of the eyes can exhibit marked binocular interaction. Other apparently monocular cells show little or no binocular interaction. 6. The disparity of the centres of the receptive fields was measured after correcting for small eye movements, which were assessed by two different techniques. For 132 cells the measured distribution of horizontal disparity (range 4.5 deg; S.D. 0.93 deg) was significantly broader than that of vertical disparity (range 2.2 deg; S.D. 0.52 deg). Sources of error in these measurements are considered. 7. The results are discussed in relation to the known connexions between visual cortex and superior colliculus and the possible role of the latter in the regulation of eye movements. PMID:1133788

  3. The central dusty torus in the active nucleus of NGC 1068.

    PubMed

    Jaffe, W; Meisenheimer, K; Röttgering, H J A; Leinert, Ch; Richichi, A; Chesneau, O; Fraix-Burnet, D; Glazenborg-Kluttig, A; Granato, G-L; Graser, U; Heijligers, B; Köhler, R; Malbet, F; Miley, G K; Paresce, F; Pel, J-W; Perrin, G; Przygodda, F; Schoeller, M; Sol, H; Waters, L B F M; Weigelt, G; Woillez, J; De Zeeuw, P T

    2004-05-01

    Active galactic nuclei (AGNs) display many energetic phenomena--broad emission lines, X-rays, relativistic jets, radio lobes--originating from matter falling onto a supermassive black hole. It is widely accepted that orientation effects play a major role in explaining the observational appearance of AGNs. Seen from certain directions, circum-nuclear dust clouds would block our view of the central powerhouse. Indirect evidence suggests that the dust clouds form a parsec-sized torus-shaped distribution. This explanation, however, remains unproved, as even the largest telescopes have not been able to resolve the dust structures. Here we report interferometric mid-infrared observations that spatially resolve these structures in the galaxy NGC 1068. The observations reveal warm (320 K) dust in a structure 2.1 parsec thick and 3.4 parsec in diameter, surrounding a smaller hot structure. As such a configuration of dust clouds would collapse in a time much shorter than the active phase of the AGN, this observation requires a continual input of kinetic energy to the cloud system from a source coexistent with the AGN. PMID:15129274

  4. The Central Amygdala Nucleus is Critical for Incubation of Methamphetamine Craving

    PubMed Central

    Li, Xuan; Zeric, Tamara; Kambhampati, Sarita; Bossert, Jennifer M; Shaham, Yavin

    2015-01-01

    Cue-induced methamphetamine seeking progressively increases after withdrawal but mechanisms underlying this ‘incubation of methamphetamine craving' are unknown. Here we studied the role of central amygdala (CeA), ventral medial prefrontal cortex (vmPFC), and orbitofrontal cortex (OFC), brain regions implicated in incubation of cocaine and heroin craving, in incubation of methamphetamine craving. We also assessed the role of basolateral amygdala (BLA) and dorsal medial prefrontal cortex (dmPFC). We trained rats to self-administer methamphetamine (10 days; 9 h/day, 0.1 mg/kg/infusion) and tested them for cue-induced methamphetamine seeking under extinction conditions during early (2 days) or late (4–5 weeks) withdrawal. We first confirmed that ‘incubation of methamphetamine craving' occurs under our experimental conditions. Next, we assessed the effect of reversible inactivation of CeA or BLA by GABAA+GABAB receptor agonists (muscimol+baclofen, 0.03+0.3 nmol) on cue-induced methamphetamine seeking during early and late withdrawal. We also assessed the effect of muscimol+baclofen reversible inactivation of vmPFC, dmPFC, and OFC on ‘incubated' cue-induced methamphetamine seeking during late withdrawal. Lever presses in the cue-induced methamphetamine extinction tests were higher during late withdrawal than during early withdrawal (incubation of methamphetamine craving). Muscimol+baclofen injections into CeA but not BLA decreased cue-induced methamphetamine seeking during late but not early withdrawal. Muscimol+baclofen injections into dmPFC, vmPFC, or OFC during late withdrawal had no effect on incubated cue-induced methamphetamine seeking. Together with previous studies, results indicate that the CeA has a critical role in incubation of both drug and non-drug reward craving and demonstrate an unexpected dissociation in mechanisms of incubation of methamphetamine vs cocaine craving. PMID:25475163

  5. Effects of lidocaine injections into the lateral parabrachial nucleus on dipsogenic and pressor response to central angiotensin 2 in rats

    NASA Technical Reports Server (NTRS)

    Menani, Jose Vanderlei; Beltz, Terry G.

    1995-01-01

    This study investigated the effects of bilateral injections of the local anesthetic, lidocaine, into the lateral parabrachial nucleus (LPBN) on the dipsogenic and pressor responses induced by intracerebroventricular (i.c.v.) injection of angiotensin 2 (ANG 2). Centrally injected ANG 2 (50 ng/1 microliter) induced water intake ( IO.2 +/- 0.8 ml/h) and pressor responses (22 +/- 1 mmHg). Prior bilateral injection of 10% lidocaine (200 nl) into the LPBN increased the water intake (14.2 +/- 1.4 ml/h), but did not change the pressor response (17 +/- 1 mmHg) to i.c.v. ANG 2. Lidocaine alone injected into the LPBN also induced a pressor response (23 +/- 3 mmHg). These results showing that bilateral LPBN injection of lidocaine increase water intake induced bv i.c.v. ANG 2 are consistent with electrolytic and neurotoxic lesion studies and suggest that the LPBN is associated with inhibitory mechanisms controlling water intake induced by ANG 2. These results also provide evidence that it is feasible to reversibly anesthetize this brain area to facilitate fluid-related ingestive behavior.

  6. Serotonin release in the central nucleus of the amygdala in response to noxious and innocuous cutaneous stimulation in anesthetized rats.

    PubMed

    Tokunaga, Ryota; Shimoju, Rie; Takagi, Noriaki; Shibata, Hideshi; Kurosawa, Mieko

    2016-07-01

    We investigated the effect of noxious (pinching) and innocuous (stroking) stimulation of skin on serotonin (5-HT) release in the central nucleus of the amygdala (CeA) in anesthetized rats. 5-HT in the CeA was collected by microdialysis methods. Dialysate output from consecutive 10-min periods was injected into a high-performance liquid chromatograph and 5-HT was measured with an electrochemical detector. Bilateral pinching of the back for 10 min increased 5-HT release significantly; 5-HT release was also increased with stimulation of the forelimb or hindlimb. In contrast, stroking of these areas decreased 5-HT release significantly. Furthermore, simultaneous stroking and pinching produced no change in the 5-HT release. In conclusion, the present study demonstrates that 5-HT release in the CeA is regulated by somatic afferent stimulation in a modality-dependent manner, and that innocuous stimulation can dampen the change in 5-HT release that occurs in response to noxious stimulation. PMID:26668011

  7. Weak orientation and direction selectivity in lateral geniculate nucleus representing central vision in the gray squirrel Sciurus carolinensis

    PubMed Central

    Zaltsman, Julia B.; Heimel, J. Alexander

    2015-01-01

    Classic studies of lateral geniculate nucleus (LGN) and visual cortex (V1) in carnivores and primates have found that a majority of neurons in LGN exhibit a center-surround organization, while V1 neurons exhibit strong orientation selectivity and, in many species, direction selectivity. Recent work in the mouse and the monkey has discovered previously unknown classes of orientation- and direction-selective neurons in LGN. Furthermore, some recent studies in the mouse report that many LGN cells exhibit pronounced orientation biases that are of comparable strength to the subthreshold inputs to V1 neurons. These results raise the possibility that, in rodents, orientation biases of individual LGN cells make a substantial contribution to cortical orientation selectivity. Alternatively, the size and contribution of orientation- or direction-selective channels from LGN to V1 may vary across mammals. To address this question, we examined orientation and direction selectivity in LGN and V1 neurons of a highly visual diurnal rodent: the gray squirrel. In the representation of central vision, only a few LGN neurons exhibited strong orientation or direction selectivity. Across the population, LGN neurons showed weak orientation biases and were much less selective for orientation compared with V1 neurons. Although direction selectivity was weak overall, LGN layers 3abc, which contain neurons that express calbindin, exhibited elevated direction selectivity index values compared with LGN layers 1 and 2. These results suggest that, for central visual fields, the contribution of orientation- and direction-selective channels from the LGN to V1 is small in the squirrel. As in other mammals, this small contribution is elevated in the calbindin-positive layers of the LGN PMID:25717157

  8. Functional topography of converging visual and auditory inputs to neurons in the rat superior colliculus.

    PubMed

    Skaliora, Irini; Doubell, Timothy P; Holmes, Nicholas P; Nodal, Fernando R; King, Andrew J

    2004-11-01

    We have used a slice preparation of the infant rat midbrain to examine converging inputs onto neurons in the deeper multisensory layers of the superior colliculus (dSC). Electrical stimulation of the superficial visual layers (sSC) and of the auditory nucleus of the brachium of the inferior colliculus (nBIC) evoked robust monosynaptic responses in dSC cells. Furthermore, the inputs from the sSC were found to be topographically organized as early as the second postnatal week and thus before opening of the eyes and ear canals. This precocious topography was found to be sculpted by GABAA-mediated inhibition of a more widespread set of connections. Tracer injections in the nBIC, both in coronal slices as well as in hemisected brains, confirmed a robust projection originating in the nBIC with distinct terminals in the proximity of the cell bodies of dSC neurons. Combined stimulation of the sSC and nBIC sites revealed that the presumptive visual and auditory inputs are summed linearly. Finally, whereas either input on its own could manifest a significant degree of paired-pulse facilitation, temporally offset stimulation of the two sites revealed no synaptic interactions, indicating again that the two inputs function independently. Taken together, these data provide the first detailed intracellular analysis of convergent sensory inputs onto dSC neurons and form the basis for further exploration of multisensory integration and developmental plasticity. PMID:15229210

  9. The level and distribution of the GABABR1 and GABABR2 receptor subunits in the rat's inferior colliculus

    PubMed Central

    Jamal, Lena; Khan, Aziz N.; Butt, Sehrish; Patel, Chirag R.; Zhang, Huiming

    2012-01-01

    The type B γ-aminobutyric acid receptor (GABAB receptor) is an important neurotransmitter receptor in the midbrain auditory structure, the inferior colliculus (IC). A functional GABAB receptor is a heterodimer consisting of two subunits, GABABR1 and GABABR2. Western blotting and immunohistochemical experiments were conducted to examine the expression of the two subunits over the IC including its central nucleus, dorsal cortex, and external cortex (ICc, ICd, and ICx). Results revealed that the two subunits existed in both cell bodies and the neuropil throughout the IC. The two subunits had similar regional distributions over the IC. The combined level of cell body and neuropil labeling was higher in the ICd than the other two subdivisions. Labeling in the ICc and ICx was stronger in the dorsal than the ventral regions. In spite of regional differences, no defined boundaries were formed between different areas. For both subunits, the regional distribution of immunoreactivity in the neuropil was parallel to that of combined immunoreactivity in the neuropil and cell bodies. The density of labeled cell bodies tended to be higher but sizes of cell bodies tended to be smaller in the ICd than in the other subdivisions. No systematic regional changes were found in the level of cell body immunoreactivity, except that GABABR2-immunoreactive cell bodies in the ICd had slightly higher optic density (OD) than in other regions. Elongated cell bodies existed throughout the IC. Many labeled cell bodies along the outline of the IC were oriented in parallel to the outline. No strong tendency of orientation was found in labeled cell bodies in ICc. Regional distributions of the subunits in ICc correlated well with inputs to this subdivision. Our finding regarding the contrast in the level of neuropil immunoreactivity among different subdivisions is consistent with the fact that the GABAB receptor has different pre- and postsynaptic functions in different IC regions. PMID:23189044

  10. Distinct Representation and Distribution of Visual Information by Specific Cell Types in Mouse Superficial Superior Colliculus

    PubMed Central

    Gale, Samuel D.

    2014-01-01

    The superficial superior colliculus (sSC) occupies a critical node in the mammalian visual system; it is one of two major retinorecipient areas, receives visual cortical input, and innervates visual thalamocortical circuits. Nonetheless, the contribution of sSC neurons to downstream neural activity and visually guided behavior is unknown and frequently neglected. Here we identified the visual stimuli to which specific classes of sSC neurons respond, the downstream regions they target, and transgenic mice enabling class-specific manipulations. One class responds to small, slowly moving stimuli and projects exclusively to lateral posterior thalamus; another, comprising GABAergic neurons, responds to the sudden appearance or rapid movement of large stimuli and projects to multiple areas, including the lateral geniculate nucleus. A third class exhibits direction-selective responses and targets deeper SC layers. Together, our results show how specific sSC neurons represent and distribute diverse information and enable direct tests of their functional role. PMID:25274823

  11. Appetitive changes during salt deprivation are paralleled by widespread neuronal adaptations in nucleus accumbens, lateral hypothalamus, and central amygdala.

    PubMed

    Tandon, Shashank; Simon, Sidney A; Nicolelis, Miguel A L

    2012-08-01

    Salt appetite is a goal-directed behavior in which salt-deprived animals ingest high salt concentrations that they otherwise find aversive. Because forebrain areas such as the lateral hypothalamus (LH), central amygdala (CeA), and nucleus accumbens (NAc) are known to play an important role in this behavior, we recorded from these areas while water-deprived (WD) and salt-deprived (SD) rats performed a two-bottle choice test between 0.5 M salt (NaCl) and 0.4 M sucrose. In the SD state, the preference ratio for high molar salt markedly increased. Electrophysiological recordings analyzed with respect to the onset of licking clusters revealed the presence of both excitatory and inhibitory neuronal responses during salt and/or sucrose consumption. In the NAc, putative medium spiny neurons and tonically active neurons exhibited excitatory and inhibitory responses. In all areas, compared with those recorded during the WD state, neurons recorded during the SD state showed an increase in the percentage of salt-evoked excitatory responses and a decrease in the percentage of sucrose-evoked inhibitory responses, suggesting that a subset of the neuronal population in these areas codes for the increased motivational and/or hedonic value of the salt solution. In addition, in the SD state, the firing of excitatory neurons in LH and CeA became more synchronized, indicating a greater functional connectivity between salt-responsive neurons in these areas. We propose that plastic changes in the feeding-related neuronal populations of these forebrain areas arise when changes in metabolic state alter the hedonic and motivational value of a particular taste stimulus. PMID:22572944

  12. Role of amygdala central nucleus in aversive learning produced by shock or by unexpected omission of food

    PubMed Central

    Purgert, Robert J.; Wheeler, Daniel S.; McDannald, Michael A.; Holland, Peter C.

    2012-01-01

    Many psychological learning theories have noted commonalities between aversive states produced by presentation of negative reinforcers such as electric shock and the omission of expected positive reinforcers such as food. Here, three groups of rats received training with one auditory cue paired with shock and another with the omission of expected food, a shock-paired cue and a food-omission control cue, or a food-omission cue and a shock control cue. Food-omission cues were established by contrast with food delivery; after extensive light-food pairings, the light was followed by the food-omission cue instead of food. Aversiveness of the food-omission cue was assessed with a conditioned punishment procedure, in which presentation of that cue was made contingent on performance of one previously-trained instrumental response, while a second response had no consequences. We found that rats with lesions of amygdala central nucleus (CeA) showed impaired acquisition of freezing to the cue paired with shock and no evidence for acquisition of aversive properties by the cue that accompanied the omission of expected food. Furthermore, analyses of Arc and Homer1a mRNAs after rats were exposed to a two-epoch test procedure that allowed assessment of gene expression produced by two different test stimuli showed that both food-omission and shock-paired cues generated more neuronal activity in CeA than appropriate control cues. However, the number of neurons that were activated by both shock and food-omission cues was not significantly greater than expected by chance. Thus, under these test conditions, different subsets of CeA neurons represented these two aversive states. PMID:22396420

  13. Inactivation of the central nucleus of the amygdala reduces the effect of punishment on cocaine self-administration in rats.

    PubMed

    Xue, YueQiang; Steketee, Jeffery D; Sun, WenLin

    2012-03-01

    Continued cocaine use despite the negative consequences is a hallmark of cocaine addiction. One such consequence is punishment, which is often used by society to curb cocaine use. Unfortunately, we know little about the mechanism involved in regulation by punishment of cocaine use. The fact that cocaine addicts continue to use cocaine despite potentially severe punishment suggests that the mechanism may be impaired. Such impairment is expected to critically contribute to compulsive cocaine use. This study was aimed at testing the hypothesis that the central nucleus of the amygdala (CeN) plays a critical role in such regulation. To this end, rats were trained to press a lever to self-administer cocaine under a chained schedule: a response on one lever (cocaine-seeking lever) led to access to the other lever (cocaine-taking lever), on which a response was reinforced by cocaine and cues. Thereafter, responses on the seeking lever were punished by footshock with a probability of 0.5. Cocaine self-administration (SA) was significantly suppressed by punishment in an intensity-dependent manner. Interestingly, rats trained with daily 6-h (extended access) but not 2-h (limited access) sessions showed resistance to the lower intensity of punishment. Inactivation of the CeN induced a robust anti-punishment effect in both groups. These data provided evidence that the CeN is a critical neural substrate involved in regulation by punishment of cocaine SA. Rats with a history of extended cocaine SA appeared to be less sensitive to punishment. The decreased sensitivity could result from the neuroplastic changes induced by extended cocaine SA in the CeN. PMID:22304754

  14. Acute tianeptine treatment selectively modulates neuronal activation in the central nucleus of the amygdala and attenuates fear extinction.

    PubMed

    Godsil, B P; Bontempi, B; Mailliet, F; Delagrange, P; Spedding, M; Jay, T M

    2015-11-01

    Antidepressant drugs are commonly prescribed treatments for anxiety disorders, and there is growing interest in understanding how these drugs impact fear extinction because extinction learning is pivotal to successful exposure-based therapy (EBT). A key objective within this domain is understanding how antidepressants alter the activation of specific elements of the limbic-based network that governs such fear processing. Chronic treatment with the antidepressant tianeptine has been shown to reduce the acquisition of extinction learning in rats, yet the drug's acute influence on activation in prefrontal and amygdalar regions, and on extinction learning are not well understood. To assess its influence on cellular activation, rats were injected with tianeptine and Fos immunoreactivity was measured in these regions. Acute tianeptine treatment selectively altered Fos expression within subdivisions of the central nucleus of the amygdala (CEA) in a bidirectional manner that varied in relation to ongoing activation within the capsular subdivision and its prefrontal and intra-amygdalar inputs. This pattern of results suggests that the drug can conditionally modulate the activation of CEA subdivisions, which contain microcircuits strongly implicated in fear processing. The effect of acute tianeptine was also examined with respect to the acquisition, consolidation and expression of fear extinction in rats. Acute tianeptine attenuated extinction learning as well as the recall of extinction memory, which underscores that acute dosing with the drug could alter learning during EBT. Together these findings provide a new perspective for understanding the mechanism supporting tianeptine's clinical efficacy, as well as its potential influence on CEA-based learning mechanisms. PMID:25560759

  15. The contribution of the central nucleus of the amygdala to individual differences in amphetamine-induced hyperactivity

    PubMed Central

    Cain, Mary E.; Coolon, Rosemary A.; Gill, Margaret J.

    2009-01-01

    Rats classified as high responders (HR) based on their response to an inescapable novel environment self-administer more amphetamine and have greater amphetamine-induced sensitization than rats classified as low responders (LR). Recent research suggests that the central nucleus of the amygdala (ACe) contributes to the elevated self-administration in HR rats. Therefore, the current study examined the role of the ACe in the expression of both amphetamine-induced sensitization and conditioned hyperactivity in HR and LR rats. Male Sprague-Dawley rats were screened for their response to inescapable novelty and classified as HR or LR rats. Rats were implanted with bilateral cannulae into the ACe and received amphetamine (1.0 mg/kg, s.c.) or saline injections immediately prior to 1-hr locomotor sessions. Following five training sessions, all rats received an infusion of muscimol (0.5 μg/0.5 μl) or phosphate buffered saline (PBS) followed by a saline injection to measure conditioned hyperactivity. HR rats displayed conditioned hyperactivity, while LR rats did not, suggesting that HR and LR rats differ in the expression of conditioned hyperactivity. While ACe inactivation attenuated the expression of conditioned hyperactivity, it did not differentially affect HR and LR rats. Following additional training and a 10 day rest period, all rats were then tested for amphetamine-induced sensitization (1.0 mg/kg) following an infusion of muscimol or PBS. Inactivation of the ACe attenuated the expression of sensitization only in HR rats. These results suggest the ACe contributes to the greater amphetamine sensitization in HR rats. PMID:19447275

  16. Vocal premotor activity in the superior colliculus.

    PubMed

    Sinha, Shiva R; Moss, Cynthia F

    2007-01-01

    Chronic neural recordings were taken from the midbrain superior colliculus (SC) of echolocating bats while they were engaged in one of two distinct behavioral tasks: virtual target amplitude discrimination (VTAD) and real oscillating target tracking (ROTT). In the VTAD task, bats used a limited range of sonar call features to discriminate the amplitude category of echoes, whereas in the ROTT task, the bat produced dynamically modulated sonar calls to track a moving target. Newly developed methods for chronic recordings in unrestrained, behaving bats reveal two consistent bouts of SC neural activity preceding the onset of sonar vocalizations in both tasks. A short lead bout occurs tightly coupled to vocal onset (VTAD, -5.1 to -2.2 ms range, -3.6 +/- 0.7 ms mean lead time; ROTT, -3.0 to + 0.4 ms range, -1.2 +/- 1.3 ms mean lead time), and this activity may play a role in marking the time of each sonar emission. A long lead bout in SC activity occurs earlier and spreads over a longer interval (VTAD, -40.6 to -8.4 ms range, -22.2 +/- 3.9 ms mean lead time; ROTT, -29.8 to -7.1 ms range, -17.5 +/- 9.1 ms mean lead time) when compared with short lead events. In the goal-directed ROTT task, the timing of long lead event times vary with the bat's sonar call duration. This finding, along with behavioral studies demonstrating that bats adjust sonar call duration as they track targets at changing distance, suggests the bat SC contributes to range-dependent adjustments of sonar call duration. PMID:17202477

  17. Connections of the superior colliculus to shoulder muscles of the rat: a dual tracing study

    PubMed Central

    Rubelowski, J. M.; Menge, M.; Distler, C.; Rothermel, M.; Hoffmann, K.-P.

    2013-01-01

    Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements. In the present study we investigated the tectofugal, in particular the tecto-reticulo-spinal projections to the shoulder and arm muscles in the rat. We simultaneously retrogradely labeled the premotor neurons in the brainstem by injection of the pseudorabies virus PrV Bartha 614 into the m. rhomboideus minor and m. acromiodeltoideus, and anterogradely visualized the tectofugal projections by intracollicular injection of the tracer FITC dextrane. Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic. This was confirmed by long survival times after virus injections into the muscles (98–101 h) after which numerous neurons in the deep layers of the SC were labeled. Transsynaptically retrogradely labeled brainstem neurons connected disynaptically to the injected muscles with adjacent tectal terminals were predominantly located in the gigantocellular nuclear complex of the reticular formation. In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus. Both tectal projections to the nucleus gigantocellularis and the pontine reticular nucleus were bilateral but ipsilaterally biased. We suggest this projection to be involved in more global functions in motivated behavior like general arousal allowing fast voluntary motor activity. PMID:23760726

  18. Autoradiographic distribution of /sup 125/I-galanin binding sites in the rat central nervous system

    SciTech Connect

    Skofitsch, G.; Sills, M.A.; Jacobowitz, D.M.

    1986-11-01

    Galanin (GAL) binding sites in coronal sections of the rat brain were demonstrated using autoradiographic methods. Scatchard analysis of /sup 125/I-GAL binding to slide-mounted tissue sections revealed saturable binding to a single class of receptors with a Kd of approximately 0.2 nM. /sup 125/I-GAL binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the following areas: prefrontal cortex, the anterior nuclei of the olfactory bulb, several nuclei of the amygdaloid complex, the dorsal septal area, dorsal bed nucleus of the stria terminalis, the ventral pallidum, the internal medullary laminae of the thalamus, medial pretectal nucleus, nucleus of the medial optic tract, borderline area of the caudal spinal trigeminal nucleus adjacent to the spinal trigeminal tract, the substantia gelatinosa and the superficial layers of the dorsal spinal cord. Moderate binding was observed in the piriform, periamygdaloid, entorhinal, insular cortex and the subiculum, the nucleus accumbens, medial forebrain bundle, anterior hypothalamic, ventromedial, dorsal premamillary, lateral and periventricular thalamic nuclei, the subzona incerta, Forel's field H1 and H2, periventricular gray matter, medial and superficial gray strata of the superior colliculus, dorsal parts of the central gray, peripeduncular area, the interpeduncular nucleus, substantia nigra zona compacta, ventral tegmental area, the dorsal and ventral parabrachial and parvocellular reticular nuclei. The preponderance of GAL-binding in somatosensory as well as in limbic areas suggests a possible involvement of GAL in a variety of brain functions.

  19. Functional Microarchitecture of the Mouse Dorsal Inferior Colliculus Revealed through In Vivo Two-Photon Calcium Imaging

    PubMed Central

    Barnstedt, Oliver; Keating, Peter; Weissenberger, Yves

    2015-01-01

    The inferior colliculus (IC) is an obligatory relay for ascending auditory inputs from the brainstem and receives descending input from the auditory cortex. The IC comprises a central nucleus (CNIC), surrounded by several shell regions, but the internal organization of this midbrain nucleus remains incompletely understood. We used two-photon calcium imaging to study the functional microarchitecture of both neurons in the mouse dorsal IC and corticocollicular axons that terminate there. In contrast to previous electrophysiological studies, our approach revealed a clear functional distinction between the CNIC and the dorsal cortex of the IC (DCIC), suggesting that the mouse midbrain is more similar to that of other mammals than previously thought. We found that the DCIC comprises a thin sheet of neurons, sometimes extending barely 100 μm below the pial surface. The sound frequency representation in the DCIC approximated the mouse's full hearing range, whereas dorsal CNIC neurons almost exclusively preferred low frequencies. The response properties of neurons in these two regions were otherwise surprisingly similar, and the frequency tuning of DCIC neurons was only slightly broader than that of CNIC neurons. In several animals, frequency gradients were observed in the DCIC, and a comparable tonotopic arrangement was observed across the boutons of the corticocollicular axons, which form a dense mesh beneath the dorsal surface of the IC. Nevertheless, acoustically responsive corticocollicular boutons were sparse, produced unreliable responses, and were more broadly tuned than DCIC neurons, suggesting that they have a largely modulatory rather than driving influence on auditory midbrain neurons. SIGNIFICANCE STATEMENT Due to its genetic tractability, the mouse is fast becoming the most popular animal model for sensory neuroscience. Nevertheless, many aspects of its neural architecture are still poorly understood. Here, we image the dorsal auditory midbrain and its

  20. Temporal resolution of neurons in cat inferior colliculus to intracochlear electrical stimulation: effects of neonatal deafening and chronic stimulation.

    PubMed

    Snyder, R; Leake, P; Rebscher, S; Beitel, R

    1995-02-01

    1. Cochlear implants have been available for > 20 yr to profoundly deaf adults who have lost their hearing after acquiring language. The success of these cochlear prostheses has encouraged the application of implants in prelingually deaf children as young as 2 yr old. To further characterize the consequences of chronic intracochlear electrical stimulation (ICES) on the developing auditory system, the temporal-response properties of single neurons in the inferior colliculus (IC) were recorded in deafened anesthetized cats. 2. The neurons were excited by unilateral ICES with the use of a scala tympani stimulating electrode implanted in the left cochlea. The electrodes were modeled after those used in cochlear implant patients. Responses of 443 units were recorded extracellularly in the contralateral (right) IC with the use of tungsten microelectrodes. Recordings were made in three groups of adult animals: neonatally deafened/chronically stimulated animals (192 units), neonatally deafened/unstimulated animals (80 units), and adult-deafened/prior normal-hearing animals (171 units). The neonatally deafened cats were deafened by multiple intramuscular injections of neomycin sulfate and never developed demonstrable hearing. Most of the deafened, chronically stimulated animals were implanted at 6 wk of age and stimulated at suprathreshold levels for 4 h/day for 3-6 mo. The unstimulated animals were implanted as adults at least 2 wk before the acute physiological experiment and were left unstimulated until the acute experiment was conducted. Prior-normal adults were deafened and implanted at least 2 wk before the acute experiment. 3. IC units were isolated with the use of a search stimulus consisting of three cycles of a 100-Hz sinusoid. Most units responded to sinusoidal stimulation with either an onset response or a sustained response. Onset units were the predominant unit found in the external nucleus, whereas sustained units were found almost exclusively in the central

  1. Excitatory/inhibitory equilibrium of the central amygdala nucleus gates anti-depressive and anxiolytic states in the hamster.

    PubMed

    Alò, Raffaella; Avolio, Ennio; Mele, Maria; Storino, Francesca; Canonaco, Alessia; Carelli, Antonio; Canonaco, Marcello

    2014-03-01

    Several studies have pointed to the amygdala as a main limbic station capable of regulating different stressful states such as anxiety and depression. In this work it was our intention to determine the role of the central amygdala nucleus (CeA) on the execution of either anxiolytic and/or anti-depressant behaviors in the hibernating hamster (Mesocricetus auratus) via infusion of CeA with the antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) specific for α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) plus the specific agonist for α4 GABAAR i.e. 4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol (THIP). Treatment with CNQX appeared to mainly prompt anti-depressant effects as shown by the achievements of swimming feats during forced swim test while THIP prevalently accounted for evident bouts of climbing when exposed to the same test. Moreover, even in the presence of the concomitant administration of both of these compounds, hamsters continued to spend more time in swimming despite this significant behavioral effect resulted to be numerically reduced for hamsters treated with only the α4 GABAAR agonist. Conversely, when these animals were tested in elevated plus maze (EPM), THIP tended to mostly favor anxiolytic activities as exhibited by stressed animals spending more time entering and remaining in EPM open arms. It was interesting to note that behavioral changes induced by both drugs appeared to be also responsible for glutamate receptor (GluR) expression differences as indicated by CNQX favoring an evident up-regulation of GluR2-containing neurons whereas THIP induced an up-regulation, this time of GluR1-containing neurons. Overall, the anti-depressant role of CNQX seems to be mostly attributed to elevated GluR2 levels while an anxiolytic-like effect of THIP was correlated to high GluR1values thereby proposing distinct GluRs as useful therapeutic sites against degenerative diseases such as depression-like behaviors. PMID:24468014

  2. Interactions between opioid-peptides-containing pathways and GABA(A)-receptors-mediated systems modulate panic-like-induced behaviors elicited by electric and chemical stimulation of the inferior colliculus.

    PubMed

    Calvo, Fabrício; Coimbra, Norberto Cysne

    2006-08-01

    Aiming to clarify the effect of interactive interconnections between the endogenous opioid peptides-neural links and GABAergic pathways on panic-like responses, in the present work, the effect of the peripheral and central administration of morphine or the non-specific opioid receptors antagonist naloxone was evaluated on the fear-induced responses (defensive attention, defensive immobility and escape behavior) elicited by electric and chemical stimulation of the inferior colliculus. Central microinjections of opioid drugs in the inferior colliculus were also performed followed by local administration of the GABA(A)-receptor antagonist bicuculline. The defensive behavior elicited by the blockade of GABAergic receptors in the inferior colliculus had been quantitatively analyzed, recording the number of crossing, jump, rotation and rearing, in each minute, during 30 min, in the open-field test. The opioid receptors stimulation with morphine decreased the defensive attention, the defensive immobility and escape behavior thresholds, and the non-specific opioid receptors blockade caused opposite effects, enhancing the defensive behavior thresholds. These effects were corroborated by either the stimulation or the inhibition of opioid receptors followed by the GABA(A) receptor blockade with bicuculline, microinjected into the inferior colliculus. There was a significant increase in the diverse fear-induced responses caused by bicuculline with the pretreatment of the inferior colliculus with morphine, and the opposite effect was recorded after the pretreatment of the inferior colliculus nuclei with naloxone followed by bicuculline local administration. These findings suggest an interaction between endogenous opioid-peptides-containing connections and GABA(A)-receptor-mediated system with direct influence on the organization of the panic-like or fear-induced responses elaborated in the inferior colliculus during critical emotional states. PMID:16797498

  3. SUPERIOR COLLICULUS LESIONS AND FLASH EVOKED POTENTIALS FROM RAT CORTEX

    EPA Science Inventory

    It is generally assumed that the primary response of the rat flash evoked potential (FEP) is activated by a retino-geniculate pathway, and that the second response reflects input to the cortex by way of the superior colliculus (SC) or other brainstem structures. In the present st...

  4. Inferior Colliculus Lesions Impair Eyeblink Conditioning in Rats

    ERIC Educational Resources Information Center

    Freeman, John H.; Halverson, Hunter E.; Hubbard, Erin M.

    2007-01-01

    The neural plasticity necessary for acquisition and retention of eyeblink conditioning has been localized to the cerebellum. However, the sources of sensory input to the cerebellum that are necessary for establishing learning-related plasticity have not been identified completely. The inferior colliculus may be a source of sensory input to the…

  5. Calcitonin gene-related peptide erases the fear memory and facilitates long-term potentiation in the central nucleus of the amygdala in rats.

    PubMed

    Wu, Xin; Zhang, Jie-Ting; Liu, Jue; Yang, Si; Chen, Tao; Chen, Jian-Guo; Wang, Fang

    2015-11-01

    Calcitonin gene-related peptide (CGRP) is a 37 amino acid neuropeptide, which plays a critical role in the central nervous system. CGRP binds to G protein-coupled receptors, including CGRP1, which couples positively to adenylyl cyclase (AC) and protein kinase A (PKA) activation. CGRP and CGRP1 receptors are enriched in central nucleus of the amygdala (CeA), the main part of the amygdala, which regulates conditioned fear memories. Here, we reported the importance of CGRP and CGRP1 receptor for synaptic plasticity in the CeA and the extinction of fear memory in rats. Our electrophysiological and behavioral in vitro and in vivo results showed exogenous application of CGRP induced an immediate and lasting long-term potentiation in the basolateral nucleus of amygdala-CeA pathway, but not in the lateral nucleus of amygdala-CeA pathway, while bilateral intra-CeA infusion CGRP (0, 5, 13 and 21 μM/side) dose dependently enhanced fear memory extinction. The effects were blocked by CGRP1 receptor antagonist (CGRP8-37 ), N-methyl-d-aspartate receptors antagonist MK801 and PKA inhibitor H89. These results demonstrate that CGRP can lead to long-term potentiation of basolateral nucleus of amygdala-CeA pathway through a PKA-dependent postsynaptic mechanism that involved N-methyl-d-aspartate receptors and enhance the extinction of fear memory in rats. Together, the results strongly support a pivotal role of CGRP in the synaptic plasticity of CeA and extinction of fear memory. Calcitonin gene-related peptide (CGRP) plays an essential role in synaptic plasticity in the amygdala and fear memory. We found that CGRP-induced chemical long-term potentiation (LTP) in a dose-dependent way in the BLA-CeA (basolateral and central nucleus of amygdala, respectively) pathway and enhanced fear memory extinction in rats through a protein kinase A (PKA)-dependent postsynaptic mechanism that involved NMDA receptors. These results support a pivotal role of CGRP in amygdala. PMID:26179152

  6. Performance of multisite silicon microprobes implanted chronically in the ventral cochlear nucleus of the cat.

    PubMed

    McCreery, Douglas; Lossinsky, Albert; Pikov, Victor

    2007-06-01

    A central auditory prosthesis based on microstimulation within the ventral cochlear nucleus (VCN) offers a means of restoring hearing to persons whose auditory nerve has been destroyed bilaterally and cannot benefit from cochlear implants. Arrays of silicon probes with 16 stimulating sites were implanted into the VCN of adult cats, for up to 314 days. Compound neuronal responses evoked from the sites in the VCN were recorded periodically in the central nucleus of the contralateral inferior colliculus (ICC). The threshold and growth of most of the responses were stable for at least 250 days after implantation of the arrays. The responses evoked from the deepest and shallowest electrode sites did exhibit some changes over time but none of the thresholds exceeded 10 microA. The thresholds and growth of the compound responses from most of the stimulating sites were very stable over time, and comparable to those of chronically implanted single-site iridium microelectrodes. Multiunit neuronal activity evoked from the stimulating sites in the VCN was recorded along the dorsolateral-ventromedial (DLVM) axis of the ICC. The distribution, span and degree of overlap of the multiunit activity demonstrated the utility of the multisite, multishank array configuration as a means of accessing the neuronal populations in the VCN that encode various acoustic frequencies. These findings are encouraging for the prospects of developing an auditory prosthesis employing multi-site silicon microprobes. PMID:17554823

  7. Projections from the nociceptive area of the central nucleus of the amygdala to the forebrain: a PHA-L study in the rat.

    PubMed

    Bourgeais, L; Gauriau, C; Bernard, J F

    2001-07-01

    The lateral capsular division (CeLC) of the central nucleus (Ce) of the amygdala, in the rat, has been shown to be the main terminal area of a spino(trigemino)-parabrachio-amygdaloid nociceptive pathway [Bernard & Besson (1990) J. Neurophysiol. 63, 473-490; Bernard et al. (1992) J. Neurophysiol. 68, 551-569; Bernard et al. (1993) J. Comp. Neurol. 329, 201-229]. The projections to the forebrain from the CeLC and adjacent regions were studied in the rat by using microinjections of Phaseolus vulgaris leucoagglutinin (PHA-L) restricted in subdivisions of the Ce and the basolateral amygdaloid nucleus anterior (BLA). Our data showed that the entire CeLC projects primarily and extensively to the substantia innominata dorsalis (SId). The terminal labelling is especially dense in the caudal aspect of the SId. The other projections of the CeLC in the forebrain were dramatically less dense. They terminate in the bed nucleus of the stria terminalis (BST) and the posterior hypothalamus (pLH). No (or only scarce) other projections were found in the remaining forebrain areas. The Ce lateral division (CeL) and the Ce medial division (CeM), adjacent to the CeLC, also project to the SId with slightly lower density labelling. However, contrary to the case of the CeLC, both the CeL and the CeM extensively project to the ventrolateral subnucleus of the BST (BSTvl) with a few additional terminals found in other regions of the lateral BST. Only the CeM projects densely to both the interstitial nucleus of the posterior limb of the anterior commissure and the caudal most portion of the pLH. The projections of the BLA are totally different from those of the Ce as they terminate in the dorsal striatum, the accumbens nucleus, the olfactory tubercle, the nucleus of olfactory tract and the rostral pole of the cingulate/frontal cortex. This study demonstrates that the major output of the nociceptive spino(trigemino)-parabrachio-CeLC pathway is to the SId. It is suggested that the Ce

  8. Hyperactivity following unilateral hearing loss in characterized cells in the inferior colliculus.

    PubMed

    Vogler, D P; Robertson, D; Mulders, W H A M

    2014-04-18

    Hyperactivity (increased spontaneous firing rates) following cochlear trauma and hearing loss has been well documented in the inferior colliculus (IC). This hyperactivity is associated with frequency regions in the IC that are closely related to regions of peripheral hearing loss. In other auditory nuclei, notably cochlear nucleus, hyperactivity has been shown to be more prevalent in particular cell types but this has not been investigated in the IC. Single-neuron spontaneous firing rates were recorded in the IC of animals after acoustic trauma (10-kHz tone at 124dB for 2h) and in sham surgery controls. Single-neuron recordings were made 2weeks later. Evoked responses to ipsi- and contralateral sound were used for classification. Classifications were based on peri-stimulus time histograms, input-output functions, frequency response areas and monaural/binaural responses. Results showed increased spontaneous firing rates in the IC following trauma, in regions corresponding to the frequencies at which there was peripheral hearing loss (12-20kHz). Most response categories, with the exception of cells showing an onset response classification, showed a significantly increased average spontaneous firing rate. These data suggest that hyperactivity in the IC is not confined to a particular response type in contrast to findings in the cochlear nucleus. This may be the result of factors intrinsic to the IC, or because of convergent input to the IC from a range of other auditory structures. PMID:24468107

  9. Onset of deconfinement in nucleus-nucleus collisions

    SciTech Connect

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2012-05-15

    The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals anomalies-the kink, horn, and step. They were predicted as signals of the deconfinement phase transition and observed by the NA49 Collaboration in central PbPb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 A GeV.

  10. Effects of aging on peripheral and central auditory processing in rats.

    PubMed

    Costa, Margarida; Lepore, Franco; Prévost, François; Guillemot, Jean-Paul

    2016-08-01

    Hearing loss is a hallmark sign in the elderly population. Decline in auditory perception provokes deficits in the ability to localize sound sources and reduces speech perception, particularly in noise. In addition to a loss of peripheral hearing sensitivity, changes in more complex central structures have also been demonstrated. Related to these, this study examines the auditory directional maps in the deep layers of the superior colliculus of the rat. Hence, anesthetized Sprague-Dawley adult (10 months) and aged (22 months) rats underwent distortion product of otoacoustic emissions (DPOAEs) to assess cochlear function. Then, auditory brainstem responses (ABRs) were assessed, followed by extracellular single-unit recordings to determine age-related effects on central auditory functions. DPOAE amplitude levels were decreased in aged rats although they were still present between 3.0 and 24.0 kHz. ABR level thresholds in aged rats were significantly elevated at an early (cochlear nucleus - wave II) stage in the auditory brainstem. In the superior colliculus, thresholds were increased and the tuning widths of the directional receptive fields were significantly wider. Moreover, no systematic directional spatial arrangement was present among the neurons of the aged rats, implying that the topographical organization of the auditory directional map was abolished. These results suggest that the deterioration of the auditory directional spatial map can, to some extent, be attributable to age-related dysfunction at more central, perceptual stages of auditory processing. PMID:27306460

  11. Merging between a Central Massive Black Hole and a Compact Stellar System: A Clue to the Origin of M31'S Nucleus

    NASA Astrophysics Data System (ADS)

    Bekki, Kenji

    2000-09-01

    The central bulge of M31 is observed to have two distinct brightness peaks with the separation of ~2 pc. S. Tremaine recently proposed the new idea that M31's nucleus is actually a single thick eccentric disk surrounding the central supermassive black hole. In order to explore the origin of the proposed eccentric disk, we numerically investigate the dynamical evolution of a merger between a central massive black hole with a mass of ~107 Msolar and a compact stellar system with a mass of ~106 Msolar and size of a few parsecs in the central 10 pc of a galactic bulge. We find that the stellar system is destroyed by the strong tidal field of the massive black hole and consequently forms a rotating nuclear thick stellar disk. The orbit of each stellar component in the developed disk is rather eccentric with a mean eccentricity of ~0.5. These results imply that M31's nuclear eccentric disk proposed by Tremaine can be formed by merging between a central massive black hole and a compact stellar system. We furthermore discuss when and how a compact stellar system is transferred into the nuclear region around a massive black hole.

  12. [Central auditory prosthesis].

    PubMed

    Lenarz, T; Lim, H; Joseph, G; Reuter, G; Lenarz, M

    2009-06-01

    Deaf patients with severe sensory hearing loss can benefit from a cochlear implant (CI), which stimulates the auditory nerve fibers. However, patients who do not have an intact auditory nerve cannot benefit from a CI. The majority of these patients are neurofibromatosis type 2 (NF2) patients who developed neural deafness due to growth or surgical removal of a bilateral acoustic neuroma. The only current solution is the auditory brainstem implant (ABI), which stimulates the surface of the cochlear nucleus in the brainstem. Although the ABI provides improvement in environmental awareness and lip-reading capabilities, only a few NF2 patients have achieved some limited open set speech perception. In the search for alternative procedures our research group in collaboration with Cochlear Ltd. (Australia) developed a human prototype auditory midbrain implant (AMI), which is designed to electrically stimulate the inferior colliculus (IC). The IC has the potential as a new target for an auditory prosthesis as it provides access to neural projections necessary for speech perception as well as a systematic map of spectral information. In this paper the present status of research and development in the field of central auditory prostheses is presented with respect to technology, surgical technique and hearing results as well as the background concepts of ABI and AMI. PMID:19517084

  13. Electrophysiologic Responses in Hamster Superior Colliculus Evoked by Regenerating Retinal Axons

    NASA Astrophysics Data System (ADS)

    Keirstead, S. A.; Rasminsky, M.; Fukuda, Y.; Carter, D. A.; Aguayo, A. J.; Vidal-Sanz, M.

    1989-10-01

    Autologous peripheral nerve grafts were used to permit and direct the regrowth of retinal ganglion cell axons from the eye to the ipsilateral superior colliculus of adult hamsters in which the optic nerves had been transected within the orbit. Extracellular recordings in the superior colliculus 15 to 18 weeks after graft insertion revealed excitatory and inhibitory postsynaptic responses to visual stimulation. The finding of light-induced responses in neurons in the superficial layers of the superior colliculus close to the graft indicates that axons regenerating from axotomized retinal ganglion cells can establish electrophysiologically functional synapses with neurons in the superior colliculus of these adult mammals.

  14. Investigating the dynamics of the brain response to music: A central role of the ventral striatum/nucleus accumbens.

    PubMed

    Mueller, Karsten; Fritz, Thomas; Mildner, Toralf; Richter, Maxi; Schulze, Katrin; Lepsien, Jöran; Schroeter, Matthias L; Möller, Harald E

    2015-08-01

    Ventral striatal activity has been previously shown to correspond well to reward value mediated by music. Here, we investigate the dynamic brain response to music and manipulated counterparts using functional magnetic resonance imaging (fMRI). Counterparts of musical excerpts were produced by either manipulating the consonance/dissonance of the musical fragments or playing them backwards (or both). Results show a greater involvement of the ventral striatum/nucleus accumbens both when contrasting listening to music that is perceived as pleasant and listening to a manipulated version perceived as unpleasant (backward dissonant), as well as in a parametric analysis for increasing pleasantness. Notably, both analyses yielded a ventral striatal response that was strongest during an early phase of stimulus presentation. A hippocampal response to the musical stimuli was also observed, and was largely mediated by processing differences between listening to forward and backward music. This hippocampal involvement was again strongest during the early response to the music. Auditory cortex activity was more strongly evoked by the original (pleasant) music compared to its manipulated counterparts, but did not display a similar decline of activation over time as subcortical activity. These findings rather suggest that the ventral striatal/nucleus accumbens response during music listening is strongest in the first seconds and then declines. PMID:25976924

  15. Controlled movement processing: superior colliculus activity associated with countermanded saccades.

    PubMed

    Paré, Martin; Hanes, Doug P

    2003-07-23

    We investigated whether the monkey superior colliculus (SC), an important midbrain structure for the regulation of saccadic eye movements, contains neurons with activity patterns sufficient to control both the cancellation and the production of saccades. We used a countermanding task to manipulate the probability that, after the presentation of a stop signal, the monkeys canceled a saccade that was planned in response to an eccentric visual stimulus. By modeling each animal's behavioral responses, with a race between GO and STOP processes leading up to either saccade initiation or cancellation, we estimated that saccade cancellation took on average 110 msec. Neurons recorded in the superior colliculus intermediate layers during this task exhibited the discharge properties expected from neurons closely involved in behavioral control. Both saccade- and fixation-related discharged differently when saccades were counter-manded instead of executed, and the time at which they changed their activity preceded the behavioral estimate of saccade cancellation obtained from the same trials by 10 and 13 msec, respectively. Furthermore, these intervals exceed the minimal amount of time needed for SC activity to influence eye movements. The additional observation that saccade-related neurons discharged significantly less when saccades were countermanded instead of executed suggests that saccades are triggered when these neurons reach a critical activation level. Altogether, these findings provide solid evidence that the superior colliculus contains the necessary neural signals to be directly involved in the decision process that regulates whether a saccade is to be produced. PMID:12878689

  16. The auditory response properties of single-on and double-on responders in the inferior colliculus of the leaf-nosed bat, Hipposideros armiger.

    PubMed

    Fu, Zi-Ying; Tang, Jia; Jen, Philip Hung-Sun; Chen, Qi-Cai

    2010-01-01

    The present study examines the response properties of neurons in the central nucleus of the inferior colliculus (IC) of the CF-FM (constant frequency-frequency-modulated) bat, Hipposideros armiger using CF, FM and CF-FM sounds as stimuli. All 169 IC neurons recorded are tonotopically organized along the dorsoventral axis of the IC. Collicular neurons have V-shaped or upper-threshold frequency tuning curves. Those neurons tuned at the predominant second harmonic have extremely sharp frequency tuning curves and low minimum thresholds. Collicular neurons typically discharge impulses to both CF and FM sounds. However, when stimulated with CF-FM sounds, most (76%) neurons only discharge impulses to the onset of CF-FM sounds (single-on responders). The remaining neurons (24%) discharge impulses to both CF and FM components (double-on responders) of CF-FM sounds. The double-on responders have higher minimum threshold and longer latency to the FM component than to the CF component of CF-FM sounds. Our data show that the FM component of the CF-FM sounds contributes significantly in shaping the discharge pattern, latency and number of impulses of IC neurons. The present study suggests that using CF-FM sounds to study auditory response properties of the CF-FM bat may be essential for a better understanding of echo analysis by the CF-FM in the real world. Because the double-on responders have shorter response latency than single-on responders, we speculate that these two types of responders may be best suited for echo analysis during different phases of hunting. PMID:19835849

  17. Recovery cycles of single-on and double-on neurons in the inferior colliculus of the leaf-nosed bat, Hipposideros armiger.

    PubMed

    Tang, Jia; Fu, Zi-Ying; Jen, Philip Hung-Sun; Chen, Qi-Cai

    2011-04-18

    Our previous study showed that when stimulated with constant frequency-frequency modulation (CF-FM) sounds, neurons in the central nucleus of the inferior colliculus of the CF-FM bat, Hipposideros armiger, either only discharged impulses to the onset of CF-FM sounds (76%, single-on neurons) or to the onset of both CF and FM components of CF-FM sounds (24%, double-on neuron) (Fu et al., 2010). The present paper reports the recovery cycles of these two types of neurons using paired CF, FM and CF-FM sounds as stimuli. Both types of neurons had similar recovery cycle for CF sounds but had the shortest recovery cycle for FM sounds. Whereas single-on neurons had similar recovery cycle for CF and CF-FM sounds, double-on neurons had longer recovery cycle for CF sounds than for CF-FM sounds. In addition, double-on neurons had significantly shorter recovery cycles than single-on neurons for FM and CF-FM sounds. Most neurons did not respond to the second sound when each pair of sounds overlapped. However, when stimulated with paired CF-FM sounds, 3 single-on and 7 double-on neurons discharged to the second sound even when both sounds overlapped. As such, they had "cyclic" recovery cycles that varied between maximum and minimum with inter-pulse intervals. Possible mechanisms underlying the different recovery cycles of these neurons are proposed. Possible biological significance of these neurons in relation to responding to varied pulse repetition rate during hunting is discussed. PMID:21338589

  18. Ephrin-B2 reverse signaling is required for topography but not pattern formation of lateral superior olivary inputs to the inferior colliculus.

    PubMed

    Wallace, Matthew M; Kavianpour, Sarah M; Gabriele, Mark L

    2013-05-01

    Graded and modular expressions of Eph-ephrins are known to provide positional information for the formation of topographic maps and patterning in the developing nervous system. Previously we have shown that ephrin-B2 is expressed in a continuous gradient across the tonotopic axis of the central nucleus of the inferior colliculus (CNIC), whereas patterns are discontinuous and modular in the lateral cortex of the IC (LCIC). The present study explores the involvement of ephrin-B2 signaling in the development of projections to the CNIC and LCIC arising from the lateral superior olivary nuclei (LSO) prior to hearing onset. Anterograde and retrograde fluorescent tracing methods in neonatal fixed tissue preparations were used to compare topographic mapping and the establishment of LSO layers/modules in wild-type and ephrin-B2(lacZ/+) mice (severely compromised reverse signaling). At birth, pioneer LSO axons occupy the ipsilateral IC in both groups but are delayed contralaterally in ephrin-B2(lacZ/+) mutants. By the onset of hearing, both wild-type and mutant projections form discernible layers bilaterally in the CNIC and modular arrangements within the ipsilateral LCIC. In contrast, ephrin-B2(lacZ/+) mice lack a reliable topography in LSO-IC projections, suggesting that fully functional ephrin-B2 reverse signaling is required for normal projection mapping. Taken together, these ephrin-B2 findings paired with known coexpression of EphA4 suggest the importance of these signaling proteins in establishing functional auditory circuits prior to experience. PMID:23042409

  19. Natural Vocalizations in the Mammalian Inferior Colliculus are Broadly Encoded by a Small Number of Independent Multi-Units.

    PubMed

    Lyzwa, Dominika; Herrmann, J Michael; Wörgötter, Florentin

    2015-01-01

    How complex natural sounds are represented by the main converging center of the auditory midbrain, the central inferior colliculus, is an open question. We applied neural discrimination to determine the variation of detailed encoding of individual vocalizations across the best frequency gradient of the central inferior colliculus. The analysis was based on collective responses from several neurons. These multi-unit spike trains were recorded from guinea pigs exposed to a spectrotemporally rich set of eleven species-specific vocalizations. Spike trains of disparate units from the same recording were combined in order to investigate whether groups of multi-unit clusters represent the whole set of vocalizations more reliably than only one unit, and whether temporal response correlations between them facilitate an unambiguous neural representation of the vocalizations. We found a spatial distribution of the capability to accurately encode groups of vocalizations across the best frequency gradient. Different vocalizations are optimally discriminated at different locations of the best frequency gradient. Furthermore, groups of a few multi-unit clusters yield improved discrimination over only one multi-unit cluster between all tested vocalizations. However, temporal response correlations between units do not yield better discrimination. Our study is based on a large set of units of simultaneously recorded responses from several guinea pigs and electrode insertion positions. Our findings suggest a broadly distributed code for behaviorally relevant vocalizations in the mammalian inferior colliculus. Responses from a few non-interacting units are sufficient to faithfully represent the whole set of studied vocalizations with diverse spectrotemporal properties. PMID:26869890

  20. Natural Vocalizations in the Mammalian Inferior Colliculus are Broadly Encoded by a Small Number of Independent Multi-Units

    PubMed Central

    Lyzwa, Dominika; Herrmann, J. Michael; Wörgötter, Florentin

    2016-01-01

    How complex natural sounds are represented by the main converging center of the auditory midbrain, the central inferior colliculus, is an open question. We applied neural discrimination to determine the variation of detailed encoding of individual vocalizations across the best frequency gradient of the central inferior colliculus. The analysis was based on collective responses from several neurons. These multi-unit spike trains were recorded from guinea pigs exposed to a spectrotemporally rich set of eleven species-specific vocalizations. Spike trains of disparate units from the same recording were combined in order to investigate whether groups of multi-unit clusters represent the whole set of vocalizations more reliably than only one unit, and whether temporal response correlations between them facilitate an unambiguous neural representation of the vocalizations. We found a spatial distribution of the capability to accurately encode groups of vocalizations across the best frequency gradient. Different vocalizations are optimally discriminated at different locations of the best frequency gradient. Furthermore, groups of a few multi-unit clusters yield improved discrimination over only one multi-unit cluster between all tested vocalizations. However, temporal response correlations between units do not yield better discrimination. Our study is based on a large set of units of simultaneously recorded responses from several guinea pigs and electrode insertion positions. Our findings suggest a broadly distributed code for behaviorally relevant vocalizations in the mammalian inferior colliculus. Responses from a few non-interacting units are sufficient to faithfully represent the whole set of studied vocalizations with diverse spectrotemporal properties. PMID:26869890

  1. Maximal subthalamic beta hypersynchrony of the local field potential in Parkinson's disease is located in the central region of the nucleus.

    PubMed

    de Solages, Camille; Hill, Bruce C; Yu, Hong; Henderson, Jaimie M; Bronte-Stewart, Helen

    2011-12-01

    A pathological marker of Parkinson's disease is the existence of abnormal synchrony of neuronal activity within the beta frequency range (13-35 Hz) in the subthalamic nucleus (STN). Recent studies examining the topography of this rhythm have located beta hypersynchrony in the most dorsal part of the STN. In contrast, this study of the topography of the local field potential beta oscillations in 18 STNs with a 1 mm spatial resolution revealed that the point of maximal beta hypersynchrony was located at 53 ± 24% of the trajectory span from the dorsal to the ventral borders of the STN (corresponding to a 3.0 ± 1.6 mm depth for a 5.9 ± 0.75 mm STN span). This suggests that maximal beta hypersynchrony is located in the central region of the nucleus and that further investigation should be done before using STN spectral profiles as an indicator for guiding placement of deep brain stimulation leads. PMID:21205981

  2. Continuous expression of corticotropin-releasing factor in the central nucleus of the amygdala emulates the dysregulation of the stress and reproductive axes

    PubMed Central

    Keen-Rhinehart, E; Michopoulos, V; Toufexis, DJ; Martin, EI; Nair, H; Ressler, KJ; Davis, M; Owens, MJ; Nemeroff, CB; Wilson, ME

    2009-01-01

    An increase in corticotropin-releasing factor (CRF) is a putative factor in the pathophysiology of stress-related disorders. As CRF expression in the central nucleus of the amygdala (CeA) is important in adaptation to chronic stress, we hypothesized that unrestrained synthesis of CRF in CeA would mimic the consequences of chronic stress exposure and cause dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, increase emotionality and disrupt reproduction. To test this hypothesis, we used a lentiviral vector to increase CRF-expression site specifically in CeA of female rats. Increased synthesis of CRF in CeA amplified CRF and arginine vasopressin peptide concentration in the paraventricular nucleus of the hypothalamus, and decreased glucocorticoid negative feedback, both markers associated with the pathophysiology of depression. In addition, continuous expression of CRF in CeA also increased the acoustic startle response and depressive-like behavior in the forced swim test. Protein levels of gonadotropin-releasing hormone in the medial preoptic area were significantly reduced by continuous expression of CRF in CeA and this was associated with a lengthening of estrous cycles. Finally, sexual motivation but not sexual receptivity was significantly attenuated by continuous CRF synthesis in ovariectomized estradiol-progesterone-primed females. These data indicate that unrestrained CRF synthesis in CeA produces a dysregulation of the HPA axis, as well as many of the behavioral, physiological and reproductive consequences associated with stress-related disorders. PMID:18698320

  3. Contrasting expressions of aggressive behavior released by lesions of the central nucleus of the amygdala during wakefulness and rapid eye movement sleep without atonia in cats.

    PubMed

    Zagrodzka, J; Hedberg, C E; Mann, G L; Morrison, A R

    1998-06-01

    Whether damage to the central nucleus of the amygdala (Ace) contributes to the predatorylike attack sometimes observed in rapid eye movement sleep without atonia (REM-A), created in cats by bilateral pontine lesions, was examined. Such lesions eliminate REM sleep skeletal muscle atonia and release elaborate behavior. Unilateral damage to the Ace alone increased affective defensive aggressive behavior toward humans and conspecifics without altering predatory behavior in wakefulness. Pontine lesions added at loci normally not leading to aggression induced predatorylike attacks in REM-A as well as the waking affective defense. Alterations of autonomic activity, the absence of relevant environmental stimuli in REM-A, or both may explain the state-related differences. PMID:9676975

  4. Differential effects of naloxone on rewarding electrical stimulation of the central nucleus of the amygdala and parabrachial complex in a place preference study.

    PubMed

    Agüera, Antonio D R; García, Raquel; Puerto, Amadeo

    2016-06-01

    The central nucleus of the amygdala (CeA) is considered to be involved in different affective, sensory, regulatory, and acquisition processes. This study analyzed whether electrical stimulation of the PB-CeA system induces preferences in a concurrent place preference (cPP) task, as observed after stimulation of the parabrachial-insular cortex (PB-IC) axis. It also examined whether the rewarding effects are naloxone-dependent. The results show that electrical stimulation of the CeA and external lateral parabrachial subnucleus (LPBe) induces consistent preference behaviors in a cPP task. However, subcutaneous administration of an opiate antagonist (naloxone; 4mg/ml/kg) blocked the rewarding effect of the parabrachial stimulation but not that of the amygdala stimulation. These results are interpreted in the context of multiple brain reward systems that appear to differ both anatomically and neurochemically, notably with respect to the opiate system. PMID:27173444

  5. Central stress-integrative circuits: Forebrain glutamatergic and GABAergic projections to the dorsomedial hypothalamus, medial preoptic area, and bed nucleus of the stria terminalis

    PubMed Central

    Myers, Brent; Dolgas, C. Mark; Kasckow, John; Cullinan, William E.; Herman, James P.

    2013-01-01

    Central regulation of hypothalamo-pituitary-adrenocortical (HPA) axis stress responses is mediated by a relatively circumscribed group of projections to the paraventricular hypothalamus (PVN). The dorsomedial hypothalamus (DMH), medial preoptic area (mPOA), and bed nucleus of the stria terminalis (BST) provide direct, predominantly inhibitory, innervation of the PVN. These PVN-projecting neurons are controlled by descending information from limbic forebrain structures, including the prefrontal cortex, amygdala, hippocampus, and septum. The neurochemical phenotype of limbic circuits targeting PVN relays has not been systematically analyzed. The current study combined retrograde tracing and immunohistochemistry/in situ hybridization to identify the specific sites of glutamatergic and GABAergic inputs to the DMH, mPOA, and BST. Following Flouro-Gold (FG) injections in the DMH, retrogradely-labeled cells co-localized with vesicular glutamate transporter mRNA in the prefrontal cortex, ventral hippocampus, and paraventricular thalamus. Co-localization of FG and glutamic acid decarboxylase mRNA was present throughout the central and medial amygdaloid nuclei and septal area. Additionally, the mPOA received predominantly GABAergic input from the septum, amygdala, and BST. The BST received glutamatergic projections from the hippocampus and basomedial amygdala, whereas GABAergic inputs arose from central and medial amygdaloid nuclei. Thus, discrete sets of neurons in the hypothalamus and BST are positioned to summate limbic inputs into PVN regulation and may play a role in HPA dysfunction and stress-related illness. PMID:23661182

  6. Different serotonin receptor agonists have distinct effects on sound-evoked responses in inferior colliculus.

    PubMed

    Hurley, Laura M

    2006-11-01

    The neuromodulator serotonin has a complex set of effects on the auditory responses of neurons within the inferior colliculus (IC), a midbrain auditory nucleus that integrates a wide range of inputs from auditory and nonauditory sources. To determine whether activation of different types of serotonin receptors is a source of the variability in serotonergic effects, four selective agonists of serotonin receptors in the serotonin (5-HT) 1 and 5-HT2 families were iontophoretically applied to IC neurons, which were monitored for changes in their responses to auditory stimuli. Different agonists had different effects on neural responses. The 5-HT1A agonist had mixed facilitatory and depressive effects, whereas 5-HT1B and 5-HT2C agonists were both largely facilitatory. Different agonists changed threshold and frequency tuning in ways that reflected their effects on spike count. When pairs of agonists were applied sequentially to the same neurons, selective agonists sometimes affected neurons in ways that were similar to serotonin, but not to other selective agonists tested. Different agonists also differentially affected groups of neurons classified by the shapes of their frequency-tuning curves, with serotonin and the 5-HT1 receptors affecting proportionally more non-V-type neurons relative to the other agonists tested. In all, evidence suggests that the diversity of serotonin receptor subtypes in the IC is likely to account for at least some of the variability of the effects of serotonin and that receptor subtypes fulfill specialized roles in auditory processing. PMID:16870843

  7. Noise reduction of coincidence detector output by the inferior colliculus of the barn owl.

    PubMed

    Christianson, G Björn; Peña, José Luis

    2006-05-31

    A recurring theme in theoretical work is that integration over populations of similarly tuned neurons can reduce neural noise. However, there are relatively few demonstrations of an explicit noise reduction mechanism in a neural network. Here we demonstrate that the brainstem of the barn owl includes a stage of processing apparently devoted to increasing the signal-to-noise ratio in the encoding of the interaural time difference (ITD), one of two primary binaural cues used to compute the position of a sound source in space. In the barn owl, the ITD is processed in a dedicated neural pathway that terminates at the core of the inferior colliculus (ICcc). The actual locus of the computation of the ITD is before ICcc in the nucleus laminaris (NL), and ICcc receives no inputs carrying information that did not originate in NL. Unlike in NL, the rate-ITD functions of ICcc neurons require as little as a single stimulus presentation per ITD to show coherent ITD tuning. ICcc neurons also displayed a greater dynamic range with a maximal difference in ITD response rates approximately double that seen in NL. These results indicate that ICcc neurons perform a computation functionally analogous to averaging across a population of similarly tuned NL neurons. PMID:16738236

  8. Inhibition sensitive to interaural time difference in the barn owl's inferior colliculus.

    PubMed

    Albeck, Y

    1997-07-01

    In spontaneously active neurons in the external nucleus of the inferior colliculus of the barn owl, a stimulus-driven discharge was followed by a quiescent period lasting tens of milliseconds before the spontaneous activity resumed. The more favorable the interaural time difference, the longer the quiet period. The duration of the quiescent period also depended on stimulus frequency. Frequencies different from the neuron's best frequency induced shorter quiescent periods, although they could elicit similar rates of impulses. Also, the duration of the quiescent period was independent of interaural intensity difference. Thus, the quiet period is not due to an after-hyperpolarization but was an inhibitory effect that depended on the activity of other neurons. In some neurons, discharge continued after the stimulus without a quiescent period and gradually decayed over a period of 50-100 ms past the stimulus offset. The similarity between the quiescent period of the neurons mentioned above and the time course of the poststimulus discharge in these neurons suggests that these neurons serve as inhibitory interneurons. PMID:9259240

  9. Estrogen receptor beta activation prevents glucocorticoid receptor-dependent effects of the central nucleus of the amygdala on behavior and neuroendocrine function.

    PubMed

    Weiser, Michael J; Foradori, Chad D; Handa, Robert J

    2010-06-01

    Neuropsychiatric disorders such as anxiety and depression have formidable economic and societal impacts. A dysregulation of the hypothalamo-pituitary-adrenal (HPA) axis leading to elevated endogenous glucocorticoid levels is often associated with such disorders. Chronically high glucocorticoid levels may act upon the central nucleus of the amygdala (CeA) to alter normally adaptive responses into those that are maladaptive and detrimental. In addition to glucocorticoids, other steroid hormones such as estradiol and androgens can also modify hormonal and behavioral responses to threatening stimuli. In particular, estrogen receptor beta (ERbeta) agonists have been shown to be anxiolytic. Consequently, these experiments addressed the hypothesis that the selective stimulation of glucocorticoid receptor (GR) in the CeA would increase anxiety-like behaviors and HPA axis reactivity to stress, and further, that an ERbeta agonist could modulate these effects. Young adult female Sprague-Dawley rats were ovariectomized and bilaterally implanted via stereotaxic surgery with a wax pellet containing the selective GR agonist RU28362 or a blank pellet, to a region just dorsal to the CeA. Four days later, animals were administered the ERbeta agonist S-DPN or vehicle (with four daily sc injections). Anxiety-type behaviors were measured using the elevated plus maze (EPM). Central RU28362 implants caused significantly higher anxiety-type behaviors in the EPM and greater plasma CORT levels than controls given a blank central implant. Moreover, S-DPN treated animals, regardless of type of central implant, displayed significantly lower anxiety-type behaviors and post-EPM plasma CORT levels than vehicle treated controls or vehicle treated animals implanted with RU28362. These results indicate that selective activation of GR within the CeA is anxiogenic, and peripheral administration of an ERbeta agonist can overcome this effect. These data suggest that estradiol signaling via ERbeta

  10. Estrogen receptor beta activation prevents glucocorticoid receptor-dependent effects of the central nucleus of the amygdala on behavior and neuroendocrine function

    PubMed Central

    Weiser, Michael J.; Foradori, Chad D.; Handa, Robert J.

    2010-01-01

    Neuropsychiatric disorders such as anxiety and depression have formidable economic and societal impacts. A dysregulation of the hypothalamo-pituitary-adrenal (HPA) axis leading to elevated endogenous glucocorticoid levels is often associated with such disorders. Chronically high glucocorticoid levels may act upon the central nucleus of the amygdala (CeA) to alter normally adaptive responses into those that are maladaptive and detrimental. In addition to glucocorticoids, other steroid hormones such as estradiol and androgens can also modify hormonal and behavioral responses to threatening stimuli. In particular, estrogen receptor beta (ERβ) agonists have been shown to be anxiolytic. Consequently, these experiments addressed the hypothesis that the selective stimulation of glucocorticoid receptor (GR) in the CeA would increase anxiety-like behaviors and HPA axis reactivity to stress, and further, that an ERβ agonist could modulate these effects. Young adult female Sprague-Dawley rats were ovariectomized and bilaterally implanted via stereotaxic surgery with a wax pellet containing the selective GR agonist RU28362 or a blank pellet, to a region just dorsal to the CeA. Four days later, animals were administered the ERβ agonist S-DPN or vehicle (with four daily sc injections). Anxiety-type behaviors were measured using the elevated plus maze (EPM). Central RU28362 implants caused significantly higher anxiety-type behaviors in the EPM and greater plasma CORT levels than controls given a blank central implant. Moreover, S-DPN treated animals, regardless of type of central implant, displayed significantly lower anxiety-type behaviors and post-EPM plasma CORT levels than vehicle treated controls or vehicle treated animals implanted with RU28362. These results indicate that selective activation of GR within the CeA is anxiogenic, and peripheral administration of an ERβ agonist can overcome this effect. These data suggest that estradiol signaling via ERβ prevents

  11. Comparison of receptive-field organization of the superior colliculus in Siamese and normal cats

    PubMed Central

    Berman, Nancy; Cynader, Max

    1972-01-01

    1. The superior colliculus has been studied in Siamese and normal cats by recording the responses of single tectal units to visual stimuli. 2. The retinotopic organization of the superior colliculus has been compared in the two breeds. In the normal cat, the contralateral half-field is represented in the central and caudal part of the colliculus, and a vertical strip of the ipsilateral half-field, 15-20° wide, is represented at the anterior tip. The Siamese cat superior colliculus receives an abnormally large projection from the ipsilateral half-field so that units with visual receptive fields which extend as far as 40° into the ipsilateral half-field can be found. The area of the tectal surface devoted to the representation of the ipsilateral half-field is about twice as large in Siamese cats as in normal cats. The enhanced representation of the ipsilateral half-field in Siamese cats is reflected in a displacement of the vertical meridian and the area centralis on the tectal surface. 3. The area centralis in the Siamese cat is located at about the same point on the tectal surface as would be occupied by a point in the visual field about 6-7° contralateral to the area centralis in the normal cat. The smallest receptive fields in both breeds are located near the area centralis. The size of the receptive field for a tectal unit seems to be determined by the retinal location of the receptive field and not by the absolute position of the unit on the tectal surface. 4. The receptive-field characteristics of tectal units show many similarities in the two breeds. The receptive fields of individual units consist of activating regions flanked by suppressive surrounds. Units respond well to stimuli of different shapes and orientation provided they are moving. The optimum stimulus for a given unit can be much smaller than the size of the activating region. About two thirds of the units studied in both breeds show directional selectivity. Most of the units studied in normal

  12. Distribution within the barn owl's inferior colliculus of neurons projecting to the optic tectum and thalamus.

    PubMed

    Arthur, Ben J

    2005-11-01

    Behavioral studies in barn owls indicate that both the optic tectum (OT) and the auditory arcopallium (AAr) mediate sound localization through the presence of neurons that respond only when sound comes from a circumscribed direction in space. The early stages of the computations leading to these so-called space-specific neurons are shared in a common brainstem pathway, which then splits at the level of the inferior colliculus (IC) such that the last computational stage is thought to be duplicated. The study presented here addresses whether the space-specific neurons in OT and AAr are indeed partially independent of each other by using anatomical methods more precise than those used in previous studies. Specifically, projection neurons in IC were retrogradely labelled with injections of fluorescein- and rhodamine-conjugated dextran amines into OT and nucleus ovoidalis (OV), the thalamic nucleus leading to AAr. By labelling the OT-projecting and OV-projecting neurons in the same owl, it was confirmed that neurons in IC project to either OV or OT but not both. However, although a segregation was generally observed between the medially positioned OV-projecting neurons and the laterally positioned OT-projecting neurons, there was also a slight overlap between the two populations. Moreover, electrolytic lesions demarcating physiological tuning properties indicate that many OV-projecting neurons are within the area containing space-specific neurons. These results highlight the need for more detailed studies elucidating the microcircuitry and corresponding physiology of IC, such as have been done in the cortices of the mammalian cerebellum and cerebrum. PMID:16175562

  13. Inhibition of the amygdala central nucleus by stimulation of cerebellar output in rats: a putative mechanism for extinction of the conditioned fear response.

    PubMed

    Magal, Ari; Mintz, Matti

    2014-11-01

    The amygdala and the cerebellum serve two distinctively different functions. The amygdala plays a role in the expression of emotional information, whereas the cerebellum is involved in the timing of discrete motor responses. Interaction between these two systems is the basis of the two-stage theory of learning, according to which an encounter with a challenging event triggers fast classical conditioning of fear-conditioned responses in the amygdala and slow conditioning of motor-conditioned responses in the cerebellum. A third stage was hypothesised when an apparent interaction between amygdala and cerebellar associative plasticity was observed: an adaptive rate of cerebellum-dependent motor-conditioned responses was associated with a decrease in amygdala-dependent fear-conditioned responses, and was interpreted as extinction of amygdala-related fear-conditioned responses by the cerebellar output. To explore this hypothesis, we mimicked some components of classical eyeblink conditioning in anesthetised rats by applying an aversive periorbital pulse as an unconditioned stimulus and a train of pulses to the cerebellar output nuclei as a cerebellar neuronal-conditioned response. The central amygdala multiple unit response to the periorbital pulse was measured with or without a preceding train to the cerebellar output nuclei. The results showed that activation of the cerebellar output nuclei prior to periorbital stimulation produced diverse patterns of inhibition of the amygdala response to the periorbital aversive stimulus, depending upon the nucleus stimulated, the laterality of the nucleus stimulated, and the stimulus interval used. These results provide a putative extinction mechanism of learned fear behavior, and could have implications for the treatment of pathologies involving abnormal fear responses by using motor training as therapy. PMID:25185877

  14. Inhibition of CaMKIIα in the Central Nucleus of Amygdala Attenuates Fentanyl-Induced Hyperalgesia in Rats.

    PubMed

    Li, Zhen; Li, Chenhong; Yin, Pingping; Wang, Zaijie Jim; Luo, Fang

    2016-10-01

    Opioid-induced hyperalgesia (OIH) is a less-studied phenomenon that has been reported in both preclinical and clinical studies. Although the underlying cause is not entirely understood, OIH is a real-life problem that affects millions of patients on a daily basis. Research has implicated the important contribution of Ca(2+)/calmodulin-dependent protein kinase IIα (CaMKIIα) to OIH at the level of spinal nociceptors. To expand our understanding of the entire brain circuitry driving OIH, in this study we investigated the role of CaMKIIα in the laterocapcular division of the central amygdala (CeLC), the conjunctive point between the spinal cord and rostro-ventral medulla. OIH was produced by repeated fentanyl administration in the rat. Correlating with the development of mechanical allodynia and thermal hyperalgesia, CaMKIIα activity was significantly elevated in the CeLC in OIH. In addition, the frequency and amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs) in CeLC neurons were significantly increased in OIH. 2-[N-(2-hidroxyethyl)-N-(4-methoxy-benzenesulfonyl)]-amino-N-(4-chlorocinnamyl)-N-methylbenzylamine, a CaMKIIα inhibitor, dose dependently reversed sensory hypersensitivity, activation of CeLC CaMKIIα, and mEPSCs in OIH. Taken together, our data for the first time implicate a critical role of CeLC CaMKIIα in OIH. PMID:27451410

  15. Antioxidant Treatments Recover the Alteration of Auditory-Evoked Potentials and Reduce Morphological Damage in the Inferior Colliculus after Perinatal Asphyxia in Rat.

    PubMed

    Revuelta, Miren; Arteaga, Olatz; Montalvo, Haizea; Alvarez, Antonia; Hilario, Enrique; Martinez-Ibargüen, Agustin

    2016-03-01

    Maturation of the auditory pathway is dependent on the central nervous system myelination and it can be affected by pathologies such as neonatal hypoxic ischemic (HI) encephalopathy. Our aim was to evaluate the functional integrity of the auditory pathway and to visualize, by histological and cellular methods, the damage to the brainstem using a neonatal rat model of HI brain injury. To carry out this morphofunctional evaluation, we studied the effects of the administration of the antioxidants nicotine, melatonin, resveratrol and docosahexaenoic acid after hypoxia-ischemia on the inferior colliculus and the auditory pathway. We found that the integrity of the auditory pathway in the brainstem was altered as a consequence of the HI insult. Thus, the auditory brainstem response (ABR) showed increased I-V and III-V wave latencies. At a histological level, HI altered the morphology of the inferior colliculus neurons, astrocytes and oligodendricytes, and at a molecular level, the mitochondria membrane potential and integrity was altered during the first hours after the HI and reactive oxygen species (ROS) activity is increased 12 h after the injury in the brainstem. Following antioxidant treatment, ABR interpeak latency intervals were restored and the body and brain weight was recovered as well as the morphology of the inferior colliculus that was similar to the control group. Our results support the hypothesis that antioxidant treatments have a protective effect on the functional changes of the auditory pathway and on the morphological damage which occurs after HI insult. PMID:25990815

  16. GABAergic control of the activity of the central nucleus of the amygdala in low- and high-anxiety rats.

    PubMed

    Skórzewska, Anna; Lehner, Małgorzata; Wisłowska-Stanek, Aleksandra; Turzyńska, Danuta; Sobolewska, Alicja; Krząścik, Paweł; Płaźnik, Adam

    2015-12-01

    The aim of this study was to examine the role of GABAergic neurotransmission in amygdala nuclei in low- (LR) and high-anxiety (HR) rats after repeated corticosterone administration and acute injection of the benzodiazepine midazolam. The animals were divided into LR and HR groups based on the duration of their conditioned freezing in a contextual fear test (CFT). Repeated daily administration of corticosterone (20 mg/kg s.c.) for 21 injections increased anxiety-like behavior in the open field and reduced body weight in both the LR and HR groups. These effects of corticosterone administration were more pronounced in the HR group. Moreover, in the HR group, chronic corticosterone administration increased the duration of freezing in the CFT test compared with the appropriate control group and treated LR rats. The behavioral effects in HR rats were accompanied by an increase in the expression of c-Fos in the lateral (LA) and central (CeA) nuclei of the amygdala and by a decrease in GABA-A alpha-2 subunit density in the CeA. Acute midazolam administration significantly attenuated the neophobia and conditioned fear responses, decreased c-Fos expression in the LA and CeA, and increased alpha-2 subunit density in the CeA only in the HR group. These studies have shown that HR rats are more susceptible to the anxiogenic effects of chronic corticosterone administration, which are associated with the attenuation of GABAergic control over the amygdala output that controls emotional responses. The current data may increase understanding of the neurobiological mechanisms responsible for individual differences in the psychopathological processes induced by repeated administration of high doses of glucocorticoids or by elevated levels of these hormones, which are associated with chronic stress and affective pathology. PMID:26318100

  17. Cardiovascular effects of noradrenaline microinjection into the medial part of the superior colliculus of unanesthetized rats.

    PubMed

    Garcia Pelosi, Gislaine; Fiacadori Tavares, Rodrigo; Barros Parron Fernandes, Karen; Morgan Aguiar Corrêa, Fernando

    2009-09-22

    The superior colliculus (SC) is a mesencephalic area involved in the mediation of defensive movements associated with cardiovascular changes. Noradrenaline (NA) is a neurotransmitter with an important role in central cardiovascular regulation exerted by several structures of the central nervous system. Although noradrenergic nerve terminals have been observed in the SC, there are no reports on the effects of local NA injection into this area. Taking this into consideration, we studied the cardiovascular effects of NA microinjection into the SC of unanesthetized rats. Microinjection of NA into the SC evoked a dose-dependent blood pressure increase and a heart rate decrease in unanesthetized rats. The pressor response to NA was not modified by intravenous pretreatment with the vasopressin v(1)-receptor antagonist dTyr(CH(2))(5)(Me)AVP, indicating a lack of vasopressin involvement in the response mediation. The effect of NA microinjection into the SC was blocked by intravenous pretreatment with the ganglionic blocker pentolinium, indicating its mediation by the sympathetic nervous system. Although the pressor response to NA was not affected by adrenal demedullation, the accompanying bradycardia was potentiated, suggesting some involvement of the sympathoadrenal system in the cardiovascular response to NA microinjection into the SC. In summary, results indicate that stimulation of noradrenergic receptors in the SC causes cardiovascular responses which are mediated by activation of both neural and adrenal sympathetic nervous system components. PMID:19615348

  18. Sodium salicylate reduces the level of GABAB receptors in the rat's inferior colliculus.

    PubMed

    Butt, S; Ashraf, F; Porter, L A; Zhang, H

    2016-03-01

    Previous studies have indicated that sodium salicylate (SS) can cause hearing abnormalities through affecting the central auditory system. In order to understand central effects of the drug, we examined how a single intraperitoneal injection of the drug changed the level of subunits of the type-B γ-aminobutyric acid receptor (GABAB receptor) in the rat's inferior colliculus (IC). Immunohistochemical and western blotting experiments were conducted three hours following a drug injection, as previous studies indicated that a tinnitus-like behavior could be reliably induced in rats within this time period. Results revealed that both subunits of the receptor, GABABR1 and GABABR2, reduced their level over the entire area of the IC. Such a reduction was observed in both cell body and neuropil regions. In contrast, no changes were observed in other brain structures such as the cerebellum. Thus, a coincidence existed between a structure-specific reduction in the level of GABAB receptor subunits in the IC and the presence of a tinnitus-like behavior. This coincidence likely suggests that a reduction in the level of GABAB receptor subunits was involved in the generation of a tinnitus-like behavior and/or used by the nervous system to restore normal hearing following application of SS. PMID:26705739

  19. Stress decreases, while central nucleus amygdala lesions increase, IL-8 and MIP-1alpha gene expression during tissue healing in non-human primates.

    PubMed

    Kalin, Ned H; Shelton, Steven E; Engeland, Christopher G; Haraldsson, H Magnus; Marucha, Phillip T

    2006-11-01

    Stress impairs healing and in part this effect is thought to be mediated by glucocorticoids. However, the brain systems that underlie the effects of stress on healing remain to be determined. Since the central nucleus of the amygdala (CeA) plays a role in mediating an individual's behavioral and physiological reactivity to stress, we investigated, in rhesus monkeys, whether selective lesions of the CeA altered the gene expression of chemokines (IL-8 and MIP-1alpha) that are associated with early dermal healing. We used rhesus monkeys because they provide an excellent animal model to investigate brain mechanisms relevant to human stress, anxiety, and psychopathology. Hypothalamic-pituitary-adrenal (HPA) activity was assessed in the monkeys prior to the wound healing experiment demonstrating that the CeA lesions reduce HPA activity. In the healing experiment, stress decreased IL-8 and MIP-1alpha gene expression in both CeA lesioned and non-lesioned animals. Conversely, the CeA lesions increased the tissue expression of IL-8 and MIP-1alpha mRNA prior to and after stress exposure. These results demonstrate that in primates the CeA is a key brain region involved in the regulation of processes associated with wound healing. Because of brain and behavioral similarities between rhesus monkeys and humans, these results are particularly relevant to understanding brain mechanisms that influence healing in humans. PMID:16574374

  20. The role of glucocorticoid receptor-dependent activity in the amygdala central nucleus and reversibility of early-life stress programmed behavior

    PubMed Central

    Arnett, M G; Pan, M S; Doak, W; Cyr, P E P; Muglia, L M; Muglia, L J

    2015-01-01

    Early-life stress (ELS) leads to sustained changes in gene expression and behavior, increasing the likelihood of developing a psychiatric disorder in adulthood. The neurobiological basis for the later-in-life psychopathology is relatively unknown. The current study used a mouse model of ELS, achieved by daily maternal separations during the first 2 weeks of postnatal life, to test the role of amygdalar glucocorticoid receptor (GR) function in mediating the persistent increase in risk-taking behaviors. ELS produced a decrease in GR mRNA in the brain, with a notable reduction in the amygdala that was associated with sustained alterations in anxiety, fear and sociability-like behaviors. Lentiviral-mediated restoration of the GR mRNA deficit, specifically within the adult central nucleus of the amygdala (CeA), reversed the enduring changes in anxiety and social behavior after ELS. These results provide evidence of lasting changes in CeA GR neural circuitry following ELS and suggest a mechanistic role for GR-regulated processes in the CeA in mediating the lifelong maladaptive behaviors of ELS. We demonstrate that the long-lasting behavioral effects of ELS are reversible later in life and implicate the involvement of CeA GR-dependent activity in the sustained dysregulation of emotion following ELS. PMID:25849981

  1. Shaker-Related Potassium Channels in the Central Medial Nucleus of the Thalamus Are Important Molecular Targets for Arousal Suppression by Volatile General Anesthetics

    PubMed Central

    Birch, Alexandra M.; Tanaka, Brian S.; Sokolov, Yuri; Goldin, Alan L.; Chandy, K. George; Hall, James E.; Alkire, Michael T.

    2013-01-01

    The molecular targets and neural circuits that underlie general anesthesia are not fully elucidated. Here, we directly demonstrate that Kv1-family (Shaker-related) delayed rectifier K+ channels in the central medial thalamic nucleus (CMT) are important targets for volatile anesthetics. The modulation of Kv1 channels by volatiles is network specific as microinfusion of ShK, a potent inhibitor of Kv1.1, Kv1.3, and Kv1.6 channels, into the CMT awakened sevoflurane-anesthetized rodents. In heterologous expression systems, sevoflurane, isoflurane, and desflurane at subsurgical concentrations potentiated delayed rectifier Kv1 channels at low depolarizing potentials. In mouse thalamic brain slices, sevoflurane inhibited firing frequency and delayed the onset of action potentials in CMT neurons, and ShK-186, a Kv1.3-selective inhibitor, prevented these effects. Our findings demonstrate the exquisite sensitivity of delayed rectifier Kv1 channels to modulation by volatile anesthetics and highlight an arousal suppressing role of Kv1 channels in CMT neurons during the process of anesthesia. PMID:24107962

  2. Inactivation of the central nucleus of the amygdala blocks classical conditioning but not conditioning-specific reflex modification of rabbit heart rate

    PubMed Central

    Burhans, Lauren B.; Schreurs, Bernard G.

    2013-01-01

    Heart rate (HR) conditioning in rabbits is a widely used model of classical conditioning of autonomic responding that is noted for being similar to the development of conditioned heart rate slowing (bradycardia) in humans. We have shown previously that in addition to HR changes to a tone conditioned stimulus (CS), the HR reflex itself can undergo associative change called conditioning-specific reflex modification (CRM) that manifests when tested in the absence of the CS. Because CRM resembles the conditioned bradycardic response to the CS, we sought to determine if HR conditioning and CRM share a common neural substrate. The central nucleus of the amygdala (CeA) is a critical part of the pathway through which conditioned bradycardia is established. To test whether the CeA is also involved in the acquisition and/or expression of CRM, we inactivated the CeA with muscimol during HR conditioning or CRM testing. CeA inactivation blocked HR conditioning without completely preventing CRM acquisition or expression. These results suggest that the CeA may therefore only play a modulatory role in CRM. Theories on the biological significance of conditioned bradycardia suggest that it may represent a state of hypervigilance that facilitates the detection of new and changing contingencies in the environment. We relate these ideas to our results and discuss how they may be relevant to the hypersensitivity observed in fear conditioning disorders like post-traumatic stress. PMID:23266790

  3. Subcortical input heterogeneity in the mouse inferior colliculus

    PubMed Central

    Geis, H-Rüdiger A P; van der Heijden, Marcel; Borst, J Gerard G

    2011-01-01

    Abstract Simultaneous intracellular recordings of nearby neocortical neurons have demonstrated that their membrane potentials are highly correlated. The correlation between the spiking activity of nearby neocortical neurons may be much smaller, suggesting that inputs are more similar than outputs. Much less is known about the similarity of inputs in subcortical sensory areas. Here we investigate this question by making simultaneous whole-cell recordings from neighbouring neurons in the dorsal cortex of the mouse inferior colliculus. No evidence for monosynaptic connections between neighbouring cells was observed, suggesting that integration of afferent signals plays a more important role than local processing. The correlation between frequency response areas of neighbouring cells varied but, surprisingly, neighbouring cells were on average not more similar in their responses to tones than non-neighbouring neurons. This large micro-heterogeneity suggests a sparse representation of acoustic features within the dorsal cortex. PMID:21727222

  4. The frequency organization of the inferior colliculus of the guinea pig: A [14C]-2-deoxyglucose study.

    PubMed

    Martin, R L; Webster, W R; Servière, J

    1988-06-01

    The [14C]-2-deoxyglucose (2-DG) technique was used to study the frequency organization of the inferior colliculus (IC) of the guinea pig. Discrete regions of heightened 2-DG labelling were observed in the ICs of animals exposed to a variety of pure-tone stimuli. Regions associated with 1, 4, 10 and 19 kHz pure tones were described and displayed in three-dimensional representations. The IC of the guinea pig was found to be arranged as a series of sheet-like, iso-frequency planes that extend throughout the nucleus from its caudal to its rostral pole. Iso-frequency planes associated with low frequencies are located dorsolaterally in the nucleus and those associated with higher frequencies are located progressively more ventromedially. The predominant orientation, in the frontal plane, of all iso-frequency planes is oblique from dorsomedial to ventrolateral. Most planes, however, twist about their caudal-to-rostral axis in a caudal-to-rostral, horizontal-to-vertical direction. The extent to which each plane twists is frequency-dependent; planes associated with low frequencies twist most and those associated with high frequencies do not twist at all. PMID:3384759

  5. Activation of corticotropin releasing factor-containing neurons in the rat central amygdala and bed nucleus of the stria terminalis following exposure to two different anxiogenic stressors.

    PubMed

    Butler, Ryan K; Oliver, Elisabeth M; Sharko, Amanda C; Parilla-Carrero, Jeffrey; Kaigler, Kris F; Fadel, Jim R; Wilson, Marlene A

    2016-05-01

    Rats exposed to the odor of a predator or to the elevated plus maze (EPM) express unique unconditioned fear behaviors. The extended amygdala has previously been demonstrated to mediate the response to both predator odor and the EPM. We seek to determine if divergent amygdalar microcircuits are associated with the different behavioral responses. The current experiments compared activation of corticotropin-releasing factor (CRF)-containing neuronal populations in the central amygdala and bed nucleus of the stria terminalis (BNST) of rats exposed to either the EPM (5 min) versus home cage controls, or predator (ferret) odor versus butyric acid, or no odor (30 min). Sections of the brains were prepared for dual-labeled immunohistochemistry and counts of c-Fos co-localized with CRF were made in the centrolateral and centromedial amygdala (CLA and CMA) as well as the dorsolateral (dl), dorsomedial (dm), and ventral (v) BNST. Ferret odor-exposed rats displayed an increase in duration and a decrease in latency of defensive burying versus control rats. Exposure to both predator stress and EPM induced neuronal activation in the BNST, but not the central amygdala, and similar levels of neuronal activation were seen in both the high and low anxiety groups in the BNST after EPM exposure. Dual-labeled immunohistochemistry showed a significant increase in the percentage of CRF/c-Fos co-localization in the vBNST of ferret odor-exposed rats compared to control and butyric acid-exposed groups as well as EPM-exposed rats compared to home cage controls. In addition, an increase in the percentage of CRF-containing neurons co-localized with c-Fos was observed in the dmBNST after EPM exposure. No changes in co-localization of CRF with c-Fos was observed with these treatments in either the CLA or CMA. These results suggest that predator odor and EPM exposure activates CRF neurons in the BNST to a much greater extent than CRF neurons of the central amygdala, and indicates unconditioned

  6. Nicotinic acetylcholine receptor subtypes involved in facilitation of GABAergic inhibition in mouse superficial superior colliculus.

    PubMed

    Endo, Toshiaki; Yanagawa, Yuchio; Obata, Kunihiko; Isa, Tadashi

    2005-12-01

    The superficial superior colliculus (sSC) is a key station in the sensory processing related to visual salience. The sSC receives cholinergic projections from the parabigeminal nucleus, and previous studies have revealed the presence of several different nicotinic acetylcholine receptor (nAChR) subunits in the sSC. In this study, to clarify the role of the cholinergic inputs to the sSC, we examined current responses induced by ACh in GABAergic and non-GABAergic sSC neurons using in vitro slice preparations obtained from glutamate decarboxylase 67-green fluorescent protein (GFP) knock-in mice in which GFP is specifically expressed in GABAergic neurons. Brief air pressure application of acetylcholine (ACh) elicited nicotinic inward current responses in both GABAergic and non-GABAergic neurons. The inward current responses in the GABAergic neurons were highly sensitive to a selective antagonist for alpha3beta2- and alpha6beta2-containing receptors, alpha-conotoxin MII (alphaCtxMII). A subset of these neurons exhibited a faster alpha-bungarotoxin-sensitive inward current component, indicating the expression of alpha7-containing nAChRs. We also found that the activation of presynaptic nAChRs induced release of GABA, which elicited a burst of miniature inhibitory postsynaptic currents mediated by GABA(A) receptors in non-GABAergic neurons. This ACh-induced GABA release was mediated mainly by alphaCtxMII-sensitive nAChRs and resulted from the activation of voltage-dependent calcium channels. Morphological analysis revealed that recorded GFP-positive neurons are interneurons and GFP-negative neurons include projection neurons. These findings suggest that nAChRs are involved in the regulation of GABAergic inhibition and modulate visual processing in the sSC. PMID:16107532

  7. Pharmacological specialization of learned auditory responses in the inferior colliculus of the barn owl.

    PubMed

    Feldman, D E; Knudsen, E I

    1998-04-15

    Neural tuning for interaural time difference (ITD) in the optic tectum of the owl is calibrated by experience-dependent plasticity occurring in the external nucleus of the inferior colliculus (ICX). When juvenile owls are subjected to a sustained lateral displacement of the visual field by wearing prismatic spectacles, the ITD tuning of ICX neurons becomes systematically altered; ICX neurons acquire novel auditory responses, termed "learned responses," to ITD values outside their normal, pre-existing tuning range. In this study, we compared the glutamatergic pharmacology of learned responses with that of normal responses expressed by the same ICX neurons. Measurements were made in the ICX using iontophoretic application of glutamate receptor antagonists. We found that in early stages of ITD tuning adjustment, soon after learned responses had been induced by experience-dependent processes, the NMDA receptor antagonist D, L-2-amino-5-phosphonopentanoic acid (AP-5) preferentially blocked the expression of learned responses of many ICX neurons compared with that of normal responses of the same neurons. In contrast, the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocked learned and normal responses equally. After long periods of prism experience, preferential blockade of learned responses by AP-5 was no longer observed. These results indicate that NMDA receptors play a preferential role in the expression of learned responses soon after these responses have been induced by experience-dependent processes, whereas later in development or with additional prism experience (we cannot distinguish which), the differential NMDA receptor-mediated component of these responses disappears. This pharmacological progression resembles the changes that occur during maturation of glutamatergic synaptic currents during early development. PMID:9526024

  8. Mechanisms of spectral and temporal integration in the mustached bat inferior colliculus

    PubMed Central

    Wenstrup, Jeffrey James; Nataraj, Kiran; Sanchez, Jason Tait

    2012-01-01

    This review describes mechanisms and circuitry underlying combination-sensitive response properties in the auditory brainstem and midbrain. Combination-sensitive neurons, performing a type of auditory spectro-temporal integration, respond to specific, properly timed combinations of spectral elements in vocal signals and other acoustic stimuli. While these neurons are known to occur in the auditory forebrain of many vertebrate species, the work described here establishes their origin in the auditory brainstem and midbrain. Focusing on the mustached bat, we review several major findings: (1) Combination-sensitive responses involve facilitatory interactions, inhibitory interactions, or both when activated by distinct spectral elements in complex sounds. (2) Combination-sensitive responses are created in distinct stages: inhibition arises mainly in lateral lemniscal nuclei of the auditory brainstem, while facilitation arises in the inferior colliculus (IC) of the midbrain. (3) Spectral integration underlying combination-sensitive responses requires a low-frequency input tuned well below a neuron's characteristic frequency (ChF). Low-ChF neurons in the auditory brainstem project to high-ChF regions in brainstem or IC to create combination sensitivity. (4) At their sites of origin, both facilitatory and inhibitory combination-sensitive interactions depend on glycinergic inputs and are eliminated by glycine receptor blockade. Surprisingly, facilitatory interactions in IC depend almost exclusively on glycinergic inputs and are largely independent of glutamatergic and GABAergic inputs. (5) The medial nucleus of the trapezoid body (MNTB), the lateral lemniscal nuclei, and the IC play critical roles in creating combination-sensitive responses. We propose that these mechanisms, based on work in the mustached bat, apply to a broad range of mammals and other vertebrates that depend on temporally sensitive integration of information across the audible spectrum. PMID:23109917

  9. Classification of frequency response areas in the inferior colliculus reveals continua not discrete classes

    PubMed Central

    Palmer, Alan R; Shackleton, Trevor M; Sumner, Christian J; Zobay, Oliver; Rees, Adrian

    2013-01-01

    A differential response to sound frequency is a fundamental property of auditory neurons. Frequency analysis in the cochlea gives rise to V-shaped tuning functions in auditory nerve fibres, but by the level of the inferior colliculus (IC), the midbrain nucleus of the auditory pathway, neuronal receptive fields display diverse shapes that reflect the interplay of excitation and inhibition. The origin and nature of these frequency receptive field types is still open to question. One proposed hypothesis is that the frequency response class of any given neuron in the IC is predominantly inherited from one of three major afferent pathways projecting to the IC, giving rise to three distinct receptive field classes. Here, we applied subjective classification, principal component analysis, cluster analysis, and other objective statistical measures, to a large population (2826) of frequency response areas from single neurons recorded in the IC of the anaesthetised guinea pig. Subjectively, we recognised seven frequency response classes (V-shaped, non-monotonic Vs, narrow, closed, tilt down, tilt up and double-peaked), that were represented at all frequencies. We could identify similar classes using our objective classification tools. Importantly, however, many neurons exhibited properties intermediate between these classes, and none of the objective methods used here showed evidence of discrete response classes. Thus receptive field shapes in the IC form continua rather than discrete classes, a finding consistent with the integration of afferent inputs in the generation of frequency response areas. The frequency disposition of inhibition in the response areas of some neurons suggests that across-frequency inputs originating at or below the level of the IC are involved in their generation. PMID:23753527

  10. Retinal and Tectal "Driver-Like" Inputs Converge in the Shell of the Mouse Dorsal Lateral Geniculate Nucleus.

    PubMed

    Bickford, Martha E; Zhou, Na; Krahe, Thomas E; Govindaiah, Gubbi; Guido, William

    2015-07-22

    The dorsal lateral geniculate nucleus (dLGN) is a model system for understanding thalamic organization and the classification of inputs as "drivers" or "modulators." Retinogeniculate terminals provide the primary excitatory drive for the relay of information to visual cortex (V1), while nonretinal inputs act in concert to modulate the gain of retinogeniculate signal transmission. How do inputs from the superior colliculus, a visuomotor structure, fit into this schema? Using a variety of anatomical, optogenetic, and in vitro physiological techniques in mice, we show that dLGN inputs from the superior colliculus (tectogeniculate) possess many of the ultrastructural and synaptic properties that define drivers. Tectogeniculate and retinogeniculate terminals converge to innervate one class of dLGN neurons within the dorsolateral shell, the primary terminal domain of direction-selective retinal ganglion cells. These dLGN neurons project to layer I of V1 to form synaptic contacts with dendrites of deeper-layer neurons. We suggest that tectogeniculate inputs act as "backseat drivers," which may alert shell neurons to movement commands generated by the superior colliculus. Significance statement: The conventional view of the dorsal lateral geniculate nucleus (dLGN) is that of a simple relay of visual information between the retina and cortex. Here we show that the dLGN receives strong excitatory input from both the retina and the superior colliculus. Thus, the dLGN is part of a specialized visual channel that provides cortex with convergent information about stimulus motion and eye movement and positioning. PMID:26203147

  11. Projections of the sensory trigeminal nucleus in a percomorph teleost, tilapia (Oreochromis niloticus).

    PubMed

    Xue, Hao-Gang; Yamamoto, Naoyuki; Yang, Chun-Ying; Kerem, Gulnisa; Yoshimoto, Masami; Sawai, Nobuhiko; Ito, Hironobu; Ozawa, Hitoshi

    2006-03-20

    The sensory trigeminal nucleus of teleosts is the rostralmost nucleus among the trigeminal sensory nuclear group in the rhombencephalon. The sensory trigeminal nucleus is known to receive the somatosensory afferents of the ophthalmic, maxillar, and mandibular nerves. However, the central connections of the sensory trigeminal nucleus remain unclear. Efferents of the sensory trigeminal nucleus were examined by means of tract-tracing methods, in a percomorph teleost, tilapia. After tracer injections to the sensory trigeminal nucleus, labeled terminals were seen bilaterally in the ventromedial thalamic nucleus, periventricular pretectal nucleus, medial part of preglomerular nucleus, stratum album centrale of the optic tectum, ventrolateral nucleus of the semicircular torus, lateral valvular nucleus, prethalamic nucleus, tegmentoterminal nucleus, and superior and inferior reticular formation, with preference for the contralateral side. Labeled terminals were also found bilaterally in the oculomotor nucleus, trochlear nucleus, trigeminal motor nucleus, facial motor nucleus, facial lobe, descending trigeminal nucleus, medial funicular nucleus, and contralateral sensory trigeminal nucleus and inferior olive. Labeled terminals in the oculomotor nucleus and trochlear nucleus showed similar densities on both sides of the brain. However, labelings in the trigeminal motor nucleus, facial motor nucleus, facial lobe, descending trigeminal nucleus, and medial funicular nucleus showed a clear ipsilateral dominance. Reciprocal tracer injection experiments to the ventromedial thalamic nucleus, optic tectum, and semicircular torus resulted in labeled cell bodies in the sensory trigeminal nucleus, with a few also in the descending trigeminal nucleus. PMID:16440296

  12. Electrical stimulation of the parabrachial nucleus induces reanimation from isoflurane general anesthesia.

    PubMed

    Muindi, Fanuel; Kenny, Jonathan D; Taylor, Norman E; Solt, Ken; Wilson, Matthew A; Brown, Emery N; Van Dort, Christa J

    2016-06-01

    Clinically, emergence from general anesthesia is viewed as a passive process where anesthetics are discontinued at the end of surgery and anesthesiologists wait for the drugs to wear off. The mechanisms involved in emergence are not well understood and there are currently no drugs that can actively reverse the state of general anesthesia. An emerging hypothesis states that brain regions that control arousal become active during emergence and are a key part of the return to wakefulness. In this study, we tested the hypothesis that electrical activation of the glutamatergic parabrachial nucleus (PBN) in the brainstem is sufficient to induce reanimation (active emergence) during continuous isoflurane general anesthesia. Using c-Fos immunohistochemistry as a marker of neural activity, we first show a selective increase in active neurons in the PBN during passive emergence from isoflurane anesthesia. We then electrically stimulated the PBN to assess whether it is sufficient to induce reanimation from isoflurane general anesthesia. Stimulation induced behavioral arousal and restoration of the righting reflex during continuous isoflurane general anesthesia. In contrast, stimulation of the nearby central inferior colliculus (CIC) did not restore the righting reflex. Spectral analysis of the electroencephalogram (EEG) revealed that stimulation produced a significant decrease in EEG delta power during PBN stimulation. The results are consistent with the hypothesis that the PBN provides critical arousal input during emergence from isoflurane anesthesia. PMID:26971629

  13. NMDA receptors regulate nicotine-enhanced brain reward function and intravenous nicotine self-administration: role of the ventral tegmental area and central nucleus of the amygdala.

    PubMed

    Kenny, Paul J; Chartoff, Elena; Roberto, Marisa; Carlezon, William A; Markou, Athina

    2009-01-01

    Nicotine is considered an important component of tobacco responsible for the smoking habit in humans. Nicotine increases glutamate-mediated transmission throughout brain reward circuitries. This action of nicotine could potentially contribute to its intrinsic rewarding and reward-enhancing properties, which motivate consumption of the drug. Here we show that the competitive N-methyl-D-aspartate (NMDA) receptor antagonist LY235959 (0.5-2.5 mg per kg) abolished nicotine-enhanced brain reward function, reflected in blockade of the lowering of intracranial self-stimulation (ICSS) thresholds usually observed after experimenter-administered (0.25 mg per kg) or intravenously self-administered (0.03 mg per kg per infusion) nicotine injections. The highest LY235959 dose (5 mg per kg) tested reversed the hedonic valence of nicotine from positive to negative, reflected in nicotine-induced elevations of ICSS thresholds. LY235959 doses that reversed nicotine-induced lowering of ICSS thresholds also markedly decreased nicotine self-administration without altering responding for food reinforcement, whereas the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist NBQX had no effects on nicotine intake. In addition, nicotine self-administration upregulated NMDA receptor subunit expression in the central nucleus of the amygdala (CeA) and ventral tegmental area (VTA), suggesting important interactions between nicotine and the NMDA receptor. Furthermore, nicotine (1 microM) increased NMDA receptor-mediated excitatory postsynaptic currents in rat CeA slices, similar to its previously described effects in the VTA. Finally, infusion of LY235959 (0.1-10 ng per side) into the CeA or VTA decreased nicotine self-administration. Taken together, these data suggest that NMDA receptors, including those in the CeA and VTA, gate the magnitude and valence of the effects of nicotine on brain reward systems, thereby regulating motivation to consume the drug. PMID:18418357

  14. Stimulation of α2-adrenergic receptors in the central nucleus of the amygdala attenuates stress-induced reinstatement of nicotine seeking in rats

    PubMed Central

    Yamada, Hidetaka; Bruijnzeel, Adrie W.

    2010-01-01

    Tobacco addiction is a chronic disorder that is characterized by craving for tobacco products, withdrawal upon smoking cessation, and relapse after periods of abstinence. Previous studies demonstrated that systemic administration of α2-adrenergic receptor agonists attenuates stress-induced reinstatement of drug seeking in rats. The aim of the present experiments was to investigate the role of noradrenergic transmission in the central nucleus of amygdala (CeA) in stress-induced reinstatement of nicotine seeking. Rats self-administered nicotine for 14–16 days and then nicotine seeking was extinguished by substituting saline for nicotine. The effect of the intra-CeA infusion of the α2-adrenergic receptor agonists clonidine and dexmedetomidine, the nonselective β1/β2-adrenergic receptor antagonist propranolol, and the α1-adrenergic receptor antagonist prazosin on stress-induced reinstatement of nicotine seeking was investigated. In all the experiments, exposure to footshocks reinstated extinguished nicotine seeking. The administration of clonidine or dexmedetomidine into the CeA attenuated stress-induced reinstatement of nicotine seeking. The administration of propranolol or prazosin into the CeA did not affect stress-induced reinstatement of nicotine seeking. Furthermore, intra-CeA administration of clonidine or dexmedetomidine did not affect operant responding for food pellets. This suggests that the effects of clonidine and dexmedetomidine on stress-induced reinstatement of nicotine seeking were not mediated by motor impairments or sedation. Taken together, these findings indicate that stimulation of α2-adrenergic receptors, but not blockade of α1 or β-adrenergic receptors, in the CeA attenuates stress-induced reinstatement of nicotine seeking. These findings suggest that α2-adrenergic receptor agonists may at least partly attenuate stress-induced reinstatement of nicotine seeking by stimulating α2-adrenergic receptors in the CeA. PMID:20854830

  15. Activation of 5-HT₁A receptors in the medial subdivision of the central nucleus of the amygdala produces anxiolytic effects in a rat model of Parkinson's disease.

    PubMed

    Sun, Yi-Na; Wang, Tao; Wang, Yong; Han, Ling-Na; Li, Li-Bo; Zhang, Yu-Ming; Liu, Jian

    2015-08-01

    Although the medial subdivision of the central nucleus of the amygdala (CeM) and serotonin-1A (5-HT1A) receptors are involved in the regulation of anxiety, their roles in Parkinson's disease (PD)-associated anxiety are still unknown. Here we assessed the importance of CeM 5-HT1A receptors for anxiety in rats with unilateral 6-hydroxydopamine (6-OHDA) lesion of the medial forebrain bundle (MFB). The lesion induced anxiety-like behaviors, increased the firing rate and burst-firing pattern of CeM γ-aminobutyric acid (GABA) neurons, as well as decreased dopamine (DA) levels in the striatum, medial prefrontal cortex (mPFC), amygdala and ventral part of hippocampus (vHip). Intra-CeM injection of the selective 5-HT1A receptor agonist 8-OH-DPAT produced anxiolytic effects in the lesioned rats, and decreased the firing rate of CeM GABAergic neurons in two groups of rats. Compared to sham-operated rats, the duration of the inhibitory effect on the firing rate of GABAergic neurons was shortened in the lesioned rats. The injection increased DA levels in the mPFC and amygdala in two groups of rats and the vHip in the lesioned rats, and increased 5-HT level in the lesioned rats, whereas it decreased NA levels in the mPFC in two groups of rats and the vHip in the lesioned rats. Moreover, the mean density of 5-HT1A receptor and GABA double-labeled neurons in the CeM was reduced after the lesioning. These results suggest that activation of CeM 5-HT1A receptor produces anxiolytic effects in the 6-OHDA-lesioned rats, which involves decreased firing rate of the GABAergic neurons, and changed monoamine levels in the limbic and limbic-related brain regions. PMID:25797491

  16. Inhibition of glutamine synthetase in the central nucleus of the amygdala induces anhedonic behavior and recurrent seizures in a rat model of mesial temporal lobe epilepsy.

    PubMed

    Gruenbaum, Shaun E; Wang, Helen; Zaveri, Hitten P; Tang, Amber B; Lee, Tih-Shih W; Eid, Tore; Dhaher, Roni

    2015-10-01

    The prevalence of depression and suicide is increased in patients with mesial temporal lobe epilepsy (MTLE); however, the underlying mechanism remains unknown. Anhedonia, a core symptom of depression that is predictive of suicide, is common in patients with MTLE. Glutamine synthetase, an astrocytic enzyme that metabolizes glutamate and ammonia to glutamine, is reduced in the amygdala in patients with epilepsy and depression and in suicide victims. Here, we sought to develop a novel model of anhedonia in MTLE by testing the hypothesis that deficiency in glutamine synthetase in the central nucleus of the amygdala (CeA) leads to epilepsy and comorbid anhedonia. Nineteen male Sprague-Dawley rats were implanted with an osmotic pump infusing either the glutamine synthetase inhibitor methionine sulfoximine [MSO (n=12)] or phosphate buffered saline [PBS (n=7)] into the right CeA. Seizure activity was monitored by video-intracranial electroencephalogram (EEG) recordings for 21days after the onset of MSO infusion. Sucrose preference, a measure of anhedonia, was assessed after 21days. Methionine sulfoximine-infused rats exhibited recurrent seizures during the monitoring period and showed decreased sucrose preference over days when compared with PBS-infused rats (p<0.01). Water consumption did not differ between the PBS-treated group and the MSO-treated group. Neurons were lost in the CeA, but not the medial amygdala, lateral amygdala, basolateral amygdala, or the hilus of the dentate gyrus, in the MSO-treated rats. The results suggest that decreased glutamine synthetase activity in the CeA is a possible common cause of anhedonia and seizures in TLE. We propose that the MSO CeA model can be used for mechanistic studies that will lead to the development and testing of novel drugs to prevent seizures, depression, and suicide in patients with TLE. PMID:26262937

  17. Inhibition of corticotropin releasing factor expression in the central nucleus of the amygdala attenuates stress-induced behavioral and endocrine responses

    PubMed Central

    Callahan, Leah B.; Tschetter, Kristi E.; Ronan, Patrick J.

    2013-01-01

    Corticotropin releasing factor (CRF) is a primary mediator of endocrine, autonomic and behavioral stress responses. Studies in both humans and animal models have implicated CRF in a wide-variety of psychiatric conditions including anxiety disorders such as post-traumatic stress disorder (PTSD), depression, sleep disorders and addiction among others. The central nucleus of the amygdala (CeA), a key limbic structure with one of the highest concentrations of CRF-producing cells outside of the hypothalamus, has been implicated in anxiety-like behavior and a number of stress-induced disorders. This study investigated the specific role of CRF in the CeA on both endocrine and behavioral responses to stress. We used RNA Interference (RNAi) techniques to locally and specifically knockdown CRF expression in CeA. Behavior was assessed using the elevated plus maze (EPM) and open field test (OF). Knocking down CRF expression in the CeA had no significant effect on measures of anxiety-like behavior in these tests. However, it did have an effect on grooming behavior, a CRF-induced behavior. Prior exposure to a stressor sensitized an amygdalar CRF effect on stress-induced HPA activation. In these stress-challenged animals silencing CRF in the CeA significantly attenuated corticosterone responses to a subsequent behavioral stressor. Thus, it appears that while CRF projecting from the CeA does not play a significant role in the expression stress-induced anxiety-like behaviors on the EPM and OF it does play a critical role in stress-induced HPA activation. PMID:24194694

  18. Inhibition of corticotropin releasing factor expression in the central nucleus of the amygdala attenuates stress-induced behavioral and endocrine responses.

    PubMed

    Callahan, Leah B; Tschetter, Kristi E; Ronan, Patrick J

    2013-01-01

    Corticotropin releasing factor (CRF) is a primary mediator of endocrine, autonomic and behavioral stress responses. Studies in both humans and animal models have implicated CRF in a wide-variety of psychiatric conditions including anxiety disorders such as post-traumatic stress disorder (PTSD), depression, sleep disorders and addiction among others. The central nucleus of the amygdala (CeA), a key limbic structure with one of the highest concentrations of CRF-producing cells outside of the hypothalamus, has been implicated in anxiety-like behavior and a number of stress-induced disorders. This study investigated the specific role of CRF in the CeA on both endocrine and behavioral responses to stress. We used RNA Interference (RNAi) techniques to locally and specifically knockdown CRF expression in CeA. Behavior was assessed using the elevated plus maze (EPM) and open field test (OF). Knocking down CRF expression in the CeA had no significant effect on measures of anxiety-like behavior in these tests. However, it did have an effect on grooming behavior, a CRF-induced behavior. Prior exposure to a stressor sensitized an amygdalar CRF effect on stress-induced HPA activation. In these stress-challenged animals silencing CRF in the CeA significantly attenuated corticosterone responses to a subsequent behavioral stressor. Thus, it appears that while CRF projecting from the CeA does not play a significant role in the expression stress-induced anxiety-like behaviors on the EPM and OF it does play a critical role in stress-induced HPA activation. PMID:24194694

  19. Impaired sodium-evoked paraventricular nucleus neuronal activation and blood pressure regulation in conscious Sprague–Dawley rats lacking central Gαi2 proteins

    PubMed Central

    Carmichael, C. Y.; Carmichael, A. C. T.; Kuwabara, J. T.; Cunningham, J. T.; Wainford, R. D.

    2016-01-01

    Aim We determined the role of brain Gαi2 proteins in mediating the neural and humoral responses of conscious male Sprague–Dawley rats to acute peripheral sodium challenge. Methods Rats pre-treated (24-h) intracerebroventricularly with a targeted oligodeoxynucleotide (ODN) (25 μg per 5 μL) to downregulate brain Gαi2 protein expression or a scrambled (SCR) control ODN were challenged with an acute sodium load (intravenous bolus 3 M NaCl; 0.14 mL per 100 g), and cardiovascular parameters were monitored for 120 min. In additional groups, hypothalamic paraventricular nucleus (PVN) Fos immunoreactivity was examined at baseline, 40, and 100 min post-sodium challenge. Results In response to intravenous hypertonic saline (HS), no difference was observed in peak change in mean arterial pressure between groups. In SCR ODN pre-treated rats, arterial pressure returned to baseline by 100 min, while it remained elevated in Gαi2 ODN pre-treated rats (P < 0.05). No difference between groups was observed in sodium-evoked increases in Fos-positive magnocellular neurons or vasopressin release. V1a receptor antagonism failed to block the prolonged elevation of arterial pressure in Gαi2 ODN pre-treated rats. A significantly greater number of Fos-positive ventrolateral parvocellular, lateral parvocellular, and medial parvocellular neurons were observed in SCR vs. Gαi2 ODN pre-treated rats at 40 and 100 min post-HS challenge (P < 0.05). In SCR, but not Gαi2 ODN pre-treated rats, HS evoked suppression of plasma norepinephrine (P < 0.05). Conclusion This highlights Gαi2 protein signal transduction as a novel central mechanism acting to differentially influence PVN parvocellular neuronal activation, sympathetic outflow, and arterial pressure in response to acute HS, independently of actions on magnocellular neurons and vasopressin release. PMID:26412230

  20. The development of frequency representation in the inferior colliculus of the kitten.

    PubMed

    Webster, W R; Martin, R L

    1991-09-01

    While morphologically the kitten's cochlea matures first at the basal or high-frequency region, behavioural and physiological evidence suggests that it responds first to low-frequency sound. Explanations of this paradox include the suggestion that the spatial representation of frequency within the cochlea changes as a function of age. We have used the [14C]-2-deoxyglucose technique to study the development of frequency representation in the central auditory system of the kitten. We report here that while the locations within the inferior colliculus (IC) where high- and mid-frequency sounds are represented shift markedly between 10 and 35 days of age, the location where low-frequency sound is represented does not alter. The IC representation of low frequencies is adult-like by 10 days of age but that of higher frequencies continues to mature until as many as 35 days. Despite its morphological immaturity with respect to other regions, the apex of the cochlea appears to be the first region to become tuned to those frequencies to which it is tuned in the adult. We found little labelling at 5 and 7 days of age to 75-80 dB stimuli, but it is quite possible that the high-frequency region might respond to very intense low frequencies before 10 days of age. to very intense low frequencies before 10 days of age. PMID:1752796

  1. Excitatory, inhibitory and facilitatory frequency response areas in the inferior colliculus of hearing impaired mice.

    PubMed

    Felix, Richard A; Portfors, Christine V

    2007-06-01

    Individuals with age-related hearing loss often have difficulty understanding complex sounds such as basic speech. The C57BL/6 mouse suffers from progressive sensorineural hearing loss and thus is an effective tool for dissecting the neural mechanisms underlying changes in complex sound processing observed in humans. Neural mechanisms important for processing complex sounds include multiple tuning and combination sensitivity, and these responses are common in the inferior colliculus (IC) of normal hearing mice. We examined neural responses in the IC of C57Bl/6 mice to single and combinations of tones to examine the extent of spectral integration in the IC after age-related high frequency hearing loss. Ten percent of the neurons were tuned to multiple frequency bands and an additional 10% displayed non-linear facilitation to the combination of two different tones (combination sensitivity). No combination-sensitive inhibition was observed. By comparing these findings to spectral integration properties in the IC of normal hearing CBA/CaJ mice, we suggest that high frequency hearing loss affects some of the neural mechanisms in the IC that underlie the processing of complex sounds. The loss of spectral integration properties in the IC during aging likely impairs the central auditory system's ability to process complex sounds such as speech. PMID:17412539

  2. Central melanopsin projections in the diurnal rodent, Arvicanthis niloticus

    PubMed Central

    Langel, Jennifer L.; Smale, Laura; Esquiva, Gema; Hannibal, Jens

    2015-01-01

    The direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. Studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsically photosensitive (ipRGCs) in mediation of these acute responses to light. ipRGCs are photosensitive due to the expression of the photopigment melanopsin; these cells use glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP) as neurotransmitters. PACAP is useful for the study of central ipRGC projections because, in the retina, it is found exclusively within melanopsin cells. Little is known about the central projections of ipRGCs in diurnal species. Here, we first characterized these cells in the retina of the diurnal Nile grass rat using immunohistochemistry (IHC). The same basic subtypes of melanopsin cells that have been described in other mammals were present, but nearly 25% of them were displaced, primarily in its superior region. PACAP was present in 87.7% of all melanopsin cells, while 97.4% of PACAP cells contained melanopsin. We then investigated central projections of ipRGCs by examining the distribution of immunoreactive PACAP fibers in intact and enucleated animals. This revealed evidence that these cells project to the suprachiasmatic nucleus, lateral geniculate nucleus (LGN), pretectum, and superior colliculus. This distribution was confirmed with injections of cholera toxin subunit β coupled with Alexa Fluor 488 in one eye and Alexa Fluor 594 in the other, combined with IHC staining of PACAP. These studies also revealed that the ventral and dorsal LGN and the caudal olivary pretectal nucleus receive less innervation from ipRGCs than that reported in nocturnal rodents. Overall, these data suggest that although ipRGCs and their projections are very similar in diurnal and nocturnal rodents, they may not be identical. PMID:26236201

  3. A tract-tracing study of the central projections of the mesencephalic nucleus of the trigeminus in the guppy (Lebistes reticulatus, teleostei), with some observations on the descending trigeminal tract.

    PubMed

    Pombal, M A; Alvarez-Otero, R; Rodicio, M C; Anadón, R

    1997-01-01

    We studied the central projections of the mesencephalic nucleus of the trigeminal nerve (MesV) in the guppy (Lebistes reticulatus), after application of horseradish peroxidase or fluorescein dextran amine into the eye orbit. A small number (1 to 13) of large mesencephalic trigeminal neurons were solid labeled in the ipsilateral rostral mesencephalon. At the level of the trigeminal nerve entrance, the united process of each mesencephalic trigeminal cell bifurcates, giving rise to a peripheral branch that exits in the trigeminal nerve and a descending branch that runs caudally in a medial bundle separated from the descending trigeminal tract. This bundle passes close to the visceromotor nuclei of the medulla oblongata. Descending processes give rise to short collaterals to the descending nucleus of the trigeminus and the ventrolateral reticular area. Most MesV descending fibres terminate in this ventrolateral field at the transition of the medulla to the spinal cord, but one or two fibres could be followed to the C6 level, where they give rise to collaterals to the dorsal funicular nucleus. No collaterals directed to the trigeminal motor nucleus, the cerebellum, or the mesencephalic tegmentum were observed. These projections were also compared with those of the descending trigeminal tract. PMID:8971415

  4. Dorsal periaqueductal gray post-stimulation freezing is counteracted by neurokinin-1 receptor antagonism in the central nucleus of the amygdala in rats.

    PubMed

    Carvalho, M C; Santos, J M; Brandão, M L

    2015-05-01

    Electrical stimulation of the dorsal periaqueductal gray (dPAG) in rats generates defensive responses that are characterized by freezing and escape behaviors, followed by post-stimulation freezing that resembles symptoms of panic attacks. dPAG post-stimulation freezing involves the processing of ascending aversive information to prosencephalic centers, including the amygdala, which allows the animal to evaluate the consequences of stressful situations. The basolateral nucleus of the amygdala (BLA) is thought to act as a filter for innate and learned aversive information that is transmitted to higher structures. The central (CeA) and medial (MeA) nuclei of the amygdala constitute an output for the expression of fear reactions through projections to limbic and brainstem regions. Neurokinin (NK) receptors are abundant in the CeA, MeA, and BLA, but their role in the expression of defensive responses and processing of aversive information that is evoked by electrical stimulation of the dPAG is still unclear. In the present study, we examined the role of NK1 receptors in these amygdala nuclei in the expression of defensive responses induced by electrical stimulation of the dPAG in rats and fear memory of this aversive stimulation. Rats were implanted with an electrode into the dPAG for electrical stimulation and one cannula in the CeA, MeA, or BLA for injections of vehicle (phosphate-buffered saline) or the NK1 receptor antagonist spantide (SPA; 100 pmol/0.2 μl). Injections of SPA into the CeA but not BLA or MeA reduced the duration of post-stimulation freezing evoked by electrical stimulation of the dPAG, without changing the aversive thresholds of freezing or escape. Twenty-four hours later, exploratory behavior was evaluated in the elevated plus maze test (EPM) in the CeA group of rats. Electrical stimulation of the dPAG rats that received vehicle exhibited higher aversion to the open arms of the EPM than sham rats that did not receive any dPAG stimulation. SPA

  5. Neonatal cortical ablation disrupts multisensory development in superior colliculus

    PubMed Central

    Jiang, Wan; Jiang, Huai; Stein, Barry E.

    2006-01-01

    The ability of cat superior colliculus (SC) neurons to synthesize information from different senses depends on influences from two areas of the cortex: the anterior ectosylvian sulcus (AES) and the rostral lateral suprasylvian sulcus (rLS). Reversibly deactivating the inputs to the SC from either of these areas in normal adults severely compromises this ability and the SC-mediated behaviors that depend on it. In the present study we found that removal of these areas in neonatal animals precluded the normal development of multisensory SC processes. At maturity there was a substantial decrease in the incidence of multisensory neurons, and those multisensory neurons that did develop were highly abnormal. Their cross-modal receptive field register was severely compromised, as was their ability to integrate cross-modal stimuli. Apparently, despite the impressive plasticity of the neonatal brain, it cannot compensate for the early loss of these cortices. Surprisingly, however, neonatal removal of either AES or rLS had comparatively minor consequences on these properties. At maturity multisensory SC neurons were quite common: they developed the characteristic spatial register among their unisensory receptive fields and exhibited normal adult-like multisensory integration. These observations suggest that during early ontogeny, when the multisensory properties of SC neurons are being crafted, AES and rLS may have the ability to compensate for the loss of one another’s cortico-collicular influences so that normal multisensory processes can develop in the SC. PMID:16267111

  6. Tinnitus-Related Changes in the Inferior Colliculus

    PubMed Central

    Berger, Joel I.; Coomber, Ben

    2015-01-01

    Tinnitus is highly complex, diverse, and difficult to treat, in part due to the fact that the underlying causes and mechanisms remain elusive. Tinnitus is generated within the auditory brain; however, consolidating our understanding of tinnitus pathophysiology is difficult due to the diversity of reported effects and the variety of implicated brain nuclei. Here, we focus on the inferior colliculus (IC), a midbrain structure that integrates the vast majority of ascending auditory information and projects via the thalamus to the auditory cortex. The IC is also a point of convergence for corticofugal input and input originating outside the auditory pathway. We review the evidence, from both studies with human subjects and from animal models, for the contribution the IC makes to tinnitus. Changes in the IC, caused by either noise exposure or drug administration, involve fundamental, heterogeneous alterations in the balance of excitation and inhibition. However, differences between hearing loss-induced pathology and tinnitus-related pathology are not well understood. Moreover, variability in tinnitus induction methodology has a significant impact on subsequent neural and behavioral changes, which could explain some of the seemingly contradictory data. Nonetheless, the IC is likely involved in the generation and persistence of tinnitus perception. PMID:25870582

  7. Serotonin shifts first-spike latencies of inferior colliculus neurons.

    PubMed

    Hurley, Laura M; Pollak, George D

    2005-08-24

    Many studies of neuromodulators have focused on changes in the magnitudes of neural responses, but fewer studies have examined neuromodulator effects on response latency. Across sensory systems, response latency is important for encoding not only the temporal structure but also the identity of stimuli. In the auditory system, latency is a fundamental response property that varies with many features of sound, including intensity, frequency, and duration. To determine the extent of neuromodulatory regulation of latency within the inferior colliculus (IC), a midbrain auditory nexus, the effects of iontophoretically applied serotonin on first-spike latencies were characterized in the IC of the Mexican free-tailed bat. Serotonin significantly altered the first-spike latencies in response to tones in 24% of IC neurons, usually increasing, but sometimes decreasing, latency. Serotonin-evoked changes in latency and spike count were not always correlated but sometimes occurred independently within individual neurons. Furthermore, in some neurons, the size of serotonin-evoked latency shifts depended on the frequency or intensity of the stimulus, as reported previously for serotonin-evoked changes in spike count. These results support the general conclusion that changes in latency are an important part of the neuromodulatory repertoire of serotonin within the auditory system and show that serotonin can change latency either in conjunction with broad changes in other aspects of neuronal excitability or in highly specific ways. PMID:16120790

  8. Nigral inhibition of GABAergic neurons in mouse superior colliculus.

    PubMed

    Kaneda, Katsuyuki; Isa, Kaoru; Yanagawa, Yuchio; Isa, Tadashi

    2008-10-22

    The current dominant concept for the control of saccadic eye movements by the basal ganglia is that release from tonic GABAergic inhibition by the substantia nigra pars reticulata (SNr) triggers burst firings of intermediate gray layer (SGI) neurons in the superior colliculus (SC) to allow saccade initiation. This hypothesis is based on the assumption that SNr cells inhibit excitatory projection neurons in the SGI. Here we show that nigrotectal fibers are connected to local GABAergic neurons in the SGI with a similar frequency to non-GABAergic neurons. This was accomplished by applying neuroanatomical tracing and slice electrophysiological experiments in GAD67-green fluorescent protein (GFP) knock-in mice, in which GABAergic neurons specifically express GFP. We also found that GABA(A), but not GABA(B), receptors subserve nigrotectal transmission. The present results revealed a novel aspect on the role of the basal ganglia in the control of saccades, e.g., the SNr not only regulates burst initiation but also modulates the spatiotemporal properties of premotor neurons via connections to local GABAergic neurons in the SC. PMID:18945914

  9. Topography of covert visual attention in human superior colliculus.

    PubMed

    Katyal, Sucharit; Zughni, Samir; Greene, Clint; Ress, David

    2010-12-01

    Experiments were performed to examine the topography of covert visual attention signals in human superior colliculus (SC), both across its surface and in its depth. We measured the retinotopic organization of SC to direct visual stimulation using a 90° wedge of moving dots that slowly rotated around fixation. Subjects (n = 5) were cued to perform a difficult speed-discrimination task in the rotating region. To measure the retinotopy of covert attention, we used a full-field array of similarly moving dots. Subjects were cued to perform the same speed-discrimination task within a 90° wedge-shaped region, and only the cue rotated around fixation. High-resolution functional magnetic resonance imaging (fMRI, 1.2 mm voxels) data were acquired throughout SC. These data were then aligned to a high-resolution T1-weighted reference volume. The SC was segmented in this volume so that the surface of the SC could be computationally modeled and to permit calculation of a depth map for laminar analysis. Retinotopic maps were obtained for both direct visual stimulation and covert attention. These maps showed a similar spatial distribution to visual stimulation maps observed in rhesus macaque and were in registration with each other. Within the depth of SC, both visual attention and stimulation produced activity primarily in the superficial and intermediate layers, but stimulation activity extended significantly more deeply than attention. PMID:20861435

  10. Functional role of the human inferior colliculus in binaural hearing.

    PubMed

    Litovsky, Ruth Y; Fligor, Brian J; Tramo, Mark J

    2002-03-01

    Psychophysical experiments were carried out in a rare case involving a 48 year old man (RJC) with a small traumatic hemorrhage of the right dorsal midbrain, including the inferior colliculus (IC). RJC had normal audiograms bilaterally, but there was a marked decrease in wave V amplitude on click-evoked brainstem auditory evoked potentials following left ear stimulation. RJC demonstrated a deficit in sound localization identification when the loudspeakers lay within the auditory hemifield contralateral to his IC lesion. Errors showed a consistent bias towards the hemifield ipsilateral to the lesion. Echo suppression was abnormally weak compared with that seen in control subjects, but only for sources contralateral to the lesion. Finally, speech intelligibility tests showed normal ability to benefit from spatial separation of target and competing speech sources. These results suggest that: (1) localizing sounds within a given hemifield relies on the integrity of the contralateral IC, (2) unilateral IC lesions give the illusion that sound sources in the 'bad' hemifield are displaced towards the 'good' hemifield, (3) the IC mediates aspects of echo suppression, and (4) lesion in the IC does not impede spatial release from masking in speech intelligibility, possibly due to that ability being more heavily mediated by cortical regions. PMID:12031527

  11. Effect of Reversible Inactivation of Superior Colliculus on Head Movements

    PubMed Central

    Walton, Mark M. G.; Bechara, Bernard; Gandhi, Neeraj J.

    2013-01-01

    Because of limitations in the oculomotor range, many gaze shifts must be accomplished using coordinated movements of the eyes and head. Stimulation and recording data have implicated the primate superior colliculus (SC) in the control of these gaze shifts. The precise role of this structure in head movement control, however, is not known. The present study uses reversible inactivation to gain insight into the role of this structure in the control of head movements, including those that accompany gaze shifts and those that occur in the absence of a change in gaze. Forty-five lidocaine injections were made in two monkeys that had been trained on a series of behavioral tasks that dissociate movements of the eyes and head. Reversible inactivation resulted in clear impairments in the animals’ ability to perform gaze shifts, manifested by increased reaction times, lower peak velocities, and increased durations. In contrast, comparable effects were not found for head movements (with or without gaze shifts) with the exception of a very small increase in reaction times of head movements associated with gaze shifts. Eye-head coordination was clearly affected by the injections with gaze onset occurring relatively later with respect to head onset. Following the injections, the head contributed slightly more to the gaze shift. These results suggest that head movements (with and without gaze shifts) can be controlled by pathways that do not involve SC. PMID:18305088

  12. Synaptogenesis and Myelination in the Nucleus/Tractus Solitarius: Potential Role in Apnea of Prematurity, Congenital Central Hypoventilation, and Sudden Infant Death Syndrome.

    PubMed

    Sarnat, Harvey B; Flores-Sarnat, Laura

    2016-05-01

    Fetuses as early as 15 weeks' gestation exhibit rhythmical respiratory movements shown by real-time ultrasonography. The nucleus/tractus solitarius is the principal brainstem respiratory center; other medullary nuclei also participate. The purpose was to determine temporal maturation of synaptogenesis. Delayed synaptic maturation may explain neurogenic apnea or hypoventilation of prematurity and some cases of sudden infant death syndrome. Sections of medulla oblongata were studied from 30 human fetal and neonatal brains 9 to 41 weeks' gestation. Synaptophysin demonstrated the immunocytochemical sequence of synaptogenesis. Other neuronal markers and myelin stain also were applied. The nucleus/tractus solitarius was similarly studied in fetuses with chromosomopathies, metabolic encephalopathies, and brain malformations. Synapse formation in the nucleus solitarius begins at about 12 weeks' gestation and matures by 15 weeks; myelination initiated at 33 weeks. Synaptogenesis was delayed in 3 fetuses with different conditions, but was not specific for only nucleus solitarius. Delayed synaptogenesis or myelination in the nucleus solitarius may play a role in neonatal hypoventilation, especially in preterm infants and in some sudden infant death syndrome cases. PMID:26661483

  13. Afferent projections to the deep mesencephalic nucleus in the rat

    SciTech Connect

    Veazey, R.B.; Severin, C.M.

    1982-01-10

    Afferent projections to the deep mesencephalic nucleus (DMN) of the rat were demonstrated with axonal transport techniques. Potential sources for projections to the DMN were first identified by injecting the nucleus with HRP and examining the cervical spinal cord, brain stem, and cortex for retrogradely labeled neurons. Areas consistently labeled were then injected with a tritiated radioisotope, the tissue processed for autoradiography, and the DMN examined for anterograde labeling. Afferent projections to the medial and/or lateral parts of the DMN were found to originate from a number of spinal, bulbar, and cortical centers. Rostral brain centers projecting to both medial and lateral parts of the DMN include the ipsilateral motor and somatosensory cortex, the entopeduncular nucleus, and zona incerta. at the level of the midbrain, the ipsilateral substantia nigra and contralateral DMN likewise project to the DMN. Furthermore, the ipsilateral superior colliculus projects to the DMN, involving mainly the lateral part of the nucleus. Afferents from caudal centers include bilateral projections from the sensory nucleus of the trigeminal complex and the nucleus medulla oblongata centralis, as well as from the contralateral dentate nucleus. The projections from the trigeminal complex and nucleus medullae oblongatae centralis terminate in the intermediate and medial parts of the DMN, whereas projections from the contralateral dentate nucleus terminate mainly in its lateral part. In general, the afferent connections of the DMN arise from diverse areas of the brain. Although most of these projections distribute throughout the entire extent of the DMN, some of them project mainly to either medial or lateral parts of the nucleus, thus suggesting that the organization of the DMN is comparable, at least in part, to that of the reticular formation of the pons and medulla, a region in which hodological differences between medial and lateral subdivisions are known to exist.

  14. Activation of the serotonin 1A receptor alters the temporal characteristics of auditory responses in the inferior colliculus.

    PubMed

    Hurley, Laura M

    2007-11-21

    Serotonin, like other neuromodulators, acts on a range of receptor types, but its effects also depend on the functional characteristics of the neurons responding to receptor activation. In the inferior colliculus (IC), an auditory midbrain nucleus, activation of a common serotonin (5-HT) receptor type, the 5-HT 1A receptor, depresses auditory-evoked responses in many neurons. Whether these effects occur differentially in different types of neurons is unknown. In the current study, the effects of iontophoretic application of the 5-HT 1A agonist 8-OH-DPAT on auditory responses were compared with the characteristic frequencies (CFs), recording depths, and control first-spike latencies of the same group of IC neurons. The 8-OH-DPAT-evoked change in response significantly correlated with first-spike latency across the population, so that response depressions were more prevalent in longer-latency neurons. The 8-OH-DPAT-evoked change in response did not correlate with CF or with recording depth. 8-OH-DPAT also altered the temporal characteristics of spike trains in a subset of neurons that fired multiple spikes in response to brief stimuli. For these neurons, activation of the 5-HT 1A receptor suppressed lagging spikes proportionally more than initial spikes. These results suggest that the 5-HT 1A receptor, by affecting the timing of the responses of both individual neurons and the neuron population, shifts the temporal profile of evoked activity within the IC. PMID:17916336

  15. Two crossed axonal projections contribute to binaural unmasking of frequency-following responses in rat inferior colliculus.

    PubMed

    Du, Yi; Ma, Tianfang; Wang, Qian; Wu, Xihong; Li, Liang

    2009-11-01

    Frequency-following responses (FFRs) are sustained potentials based on phase-locked neural activities elicited by low- to medium-frequency periodical sound waveforms. Human brainstem FFRs, which are able to encode some critical acoustic features of speech, can be unmasked by binaural processing. However, the underlying unmasking mechanisms have not previously been reported. In rats, most neurons in the inferior colliculus (IC) exhibit binaural responses which are affected by axonal projections from both the contralateral dorsal nucleus of the lateral lemniscus (DNLL) and the contralateral IC. The present study investigated whether the contralateral DNLL and the contralateral IC modulate binaural unmasking of FFRs recorded in the rat IC. The results show that IC FFRs to the rat pain call (chatter) were enhanced by local injection of the excitatory glutamate receptor antagonist kynurenic acid (KYNA) into the contralateral DNLL but were reduced by KYNA injection into the contralateral IC. Introducing a disparity between the interaural time difference (ITD) of the FFR-eliciting chatter and the ITD of the masking noise enhanced IC FFRs. Moreover, the ITD-disparity-induced FFR enhancement was weakened by injection of KYNA into either the contralateral DNLL or the contralateral IC when the ipsilateral chatter preceded the contralateral chatter. Thus, binaural hearing can improve IC FFRs against noise masking. More importantly, both inhibitory projections from the contralateral DNLL and excitatory projections from the contralateral IC modulate IC FFRs and play a role in forming binaural unmasking of IC FFRs. PMID:19840111

  16. HRP study of the central components of the trigeminal nerve in the larval sea lamprey: organization and homology of the primary medullary and spinal nucleus of the trigeminus.

    PubMed

    Anadón, R; De Miguel, E; Gonzalez-Fuentes, M J; Rodicio, C

    1989-05-22

    The medullary and spinal connections of the trigeminal nerve of larval sea lampreys Petromyzon marinus were studied by anterograde and retrograde HRP transport after application into the orbit. Three components were found, all of them ipsilateral: 1) The motor nucleus was undivided in the larva, and its neurons possessed a rich dendritic tree. The single motor root was well separated from the sensory root. 2) The descending root was laterally located, and its fibers ran compactly to spinal levels. 3) Most medullary and many rostral spinal dorsal cells were labeled. Dorsal cells, which were mostly multipolar, had numerous mutual contacts. Some dorsal cell processes contacted the fourth ventricle. The name "primary medullary and spinal nucleus of the trigeminal nerve" (PMSV) is proposed for these dorsal cells. Medullary dorsal cells were not labeled by applying HRP at the level of spinal nerves, but application to the vagus nerve did label some. The possible relationship of this nucleus with the mesencephalic trigeminal nucleus of jawed vertebrates is discussed. PMID:2745757

  17. Spatiotemporal structure of visual receptive fields in macaque superior colliculus.

    PubMed

    Churan, Jan; Guitton, Daniel; Pack, Christopher C

    2012-11-01

    Saccades are useful for directing the high-acuity fovea to visual targets that are of behavioral relevance. The selection of visual targets for eye movements involves the superior colliculus (SC), where many neurons respond to visual stimuli. Many of these neurons are also activated before and during saccades of specific directions and amplitudes. Although the role of the SC in controlling eye movements has been thoroughly examined, far less is known about the nature of the visual responses in this area. We have, therefore, recorded from neurons in the intermediate layers of the macaque SC, while using a sparse-noise mapping procedure to obtain a detailed characterization of the spatiotemporal structure of visual receptive fields. We find that SC responses to flashed visual stimuli start roughly 50 ms after the onset of the stimulus and last for on average ~70 ms. About 50% of these neurons are strongly suppressed by visual stimuli flashed at certain locations flanking the excitatory center, and the spatiotemporal pattern of suppression exerts a predictable influence on the timing of saccades. This suppression may, therefore, contribute to the filtering of distractor stimuli during target selection. We also find that saccades affect the processing of visual stimuli by SC neurons in a manner that is quite similar to the saccadic suppression and postsaccadic enhancement that has been observed in the cortex and in perception. However, in contrast to what has been observed in the cortex, decreased visual sensitivity was generally associated with increased firing rates, while increased sensitivity was associated with decreased firing rates. Overall, these results suggest that the processing of visual stimuli by SC receptive fields can influence oculomotor behavior and that oculomotor signals originating in the SC can shape perisaccadic visual perception. PMID:22933722

  18. Segregated Anatomical Input to Sub-Regions of the Rodent Superior Colliculus Associated with Approach and Defense

    PubMed Central

    Comoli, Eliane; Das Neves Favaro, Plínio; Vautrelle, Nicolas; Leriche, Mariana; Overton, Paul G.; Redgrave, Peter

    2012-01-01

    The superior colliculus (SC) is responsible for sensorimotor transformations required to direct gaze toward or away from unexpected, biologically salient events. Significant changes in the external world are signaled to SC through primary multisensory afferents, spatially organized according to a retinotopic topography. For animals, where an unexpected event could indicate the presence of either predator or prey, early decisions to approach or avoid are particularly important. Rodents’ ecology dictates predators are most often detected initially as movements in upper visual field (mapped in medial SC), while appetitive stimuli are normally found in lower visual field (mapped in lateral SC). Our purpose was to exploit this functional segregation to reveal neural sites that can bias or modulate initial approach or avoidance responses. Small injections of Fluoro-Gold were made into medial or lateral sub-regions of intermediate and deep layers of SC (SCm/SCl). A remarkable segregation of input to these two functionally defined areas was found. (i) There were structures that projected only to SCm (e.g., specific cortical areas, lateral geniculate and suprageniculate thalamic nuclei, ventromedial and premammillary hypothalamic nuclei, and several brainstem areas) or SCl (e.g., primary somatosensory cortex representing upper body parts and vibrissae and parvicellular reticular nucleus in the brainstem). (ii) Other structures projected to both SCm and SCl but from topographically segregated populations of neurons (e.g., zona incerta and substantia nigra pars reticulata). (iii) There were a few brainstem areas in which retrogradely labeled neurons were spatially overlapping (e.g., pedunculopontine nucleus and locus coeruleus). These results indicate significantly more structures across the rat neuraxis are in a position to modulate defense responses evoked from SCm, and that neural mechanisms modulating SC-mediated defense or appetitive behavior are almost entirely

  19. [Involvement of cross interaction between central cholinergic and histaminergic systems in the nucleus tractus solitarius in regulating carotid sinus baroreceptor reflex].

    PubMed

    Hu, Li-Xun; Zhang, Guo-Xing; Zhang, Yu-Ying; Zhao, Hong-Fen; Yu, Kang-Ying; Wang, Guo-Qing

    2013-12-25

    The carotid sinus baroreceptor reflex (CSR) is an important approach for regulating arterial blood pressure homeostasis instantaneously and physiologically. Activation of the central histaminergic or cholinergic systems results in CSR functional inhibitory resetting. However, it is unclear whether two systems at the nucleus tractus solitarius (NTS) level display cross interaction to regulate the CSR or not. In the present study, the left or right carotid sinus region was isolated from the systemic circulation in Sprague-Dawley rats (sinus nerve was reserved) anesthetized with pentobarbital sodium. Respective intubation was conducted into one side isolated carotid sinus and into the femoral artery for recording the intracarotid sinus pressure (ISP) and mean arterial pressure (MAP) simultaneously with pressure transducers connection in vivo. ISP was set at the level of 0 mmHg to eliminate the effect of initial internal pressure of the carotid sinus on the CSR function. To trigger CSR, the ISP was quickly elevated from 0 mmHg to 280 mmHg in a stepwise manner (40 mmHg) which was added at every step for over 4 s, and then ISP returned to 0 mmHg in similar steps. The original data of ISP and corresponding MAP were fitted to a modified logistic equation with five parameters to obtain the ISP-MAP, ISP-Gain relationship curves and the CSR characteristic parameters, which were statistically compared and analyzed separately. Under the precondition of no influence on the basic levels of the artery blood pressure, the effects and potential regulatory mechanism of preceding microinjection with different cholinoceptor antagonists, the selective cholinergic M1 receptor antagonist, i.e., pirenzepine (PRZ), the M2 receptor antagonist, i.e., methoctramine (MTR) or the N1 receptor antagonist, i.e., hexamethonium (HEX) into the NTS on the changes in function of CSR induced by intracerebroventricular injection (i.c.v.) of histamine (HA) in rats were observed. Meanwhile, the actions and

  20. Forward masking in the medial nucleus of the trapezoid body of the rat.

    PubMed

    Gao, Fei; Berrebi, Albert S

    2016-05-01

    Perception of acoustic stimuli is modulated by the temporal and spectral relationship between sound components. Forward masking experiments show that the perception threshold for a probe tone is significantly impaired by a preceding masker stimulus. Forward masking has been systematically studied at the level of the auditory nerve, cochlear nucleus, inferior colliculus and auditory cortex, but not yet in the superior olivary complex. The medial nucleus of the trapezoid body (MNTB), a principal cell group of the superior olive, plays an essential role in sound localization. The MNTB receives excitatory input from the contralateral cochlear nucleus via the calyces of Held and innervates the ipsilateral lateral and medial superior olives, as well as the superior paraolivary nucleus. Here, we performed single-unit extracellular recordings in the MNTB of rats. Using a forward masking paradigm previously employed in studies of the inferior colliculus and auditory nerve, we determined response thresholds for a 20-ms characteristic frequency pure tone (the probe), and then presented it in conjunction with another tone (the masker) that was varied in intensity, duration, and frequency; we also systematically varied the masker-to-probe delay. Probe response thresholds increased and response magnitudes decreased when a masker was presented. The forward suppression effects were greater when masker level and masker duration were increased, when the masker frequency approached the MNTB unit's characteristic frequency, and as the masker-to-probe delay was shortened. Probe threshold shifts showed an exponential decay as the masker-to-probe delay increased. PMID:25921974

  1. Cytoarchitectural and functional abnormalities of the inferior colliculus in sudden unexplained perinatal death.

    PubMed

    Lavezzi, Anna M; Pusiol, Teresa; Matturri, Luigi

    2015-02-01

    The inferior colliculus is a mesencephalic structure endowed with serotonergic fibers that plays an important role in the processing of acoustic information. The implication of the neuromodulator serotonin also in the aetiology of sudden unexplained fetal and infant death syndromes and the demonstration in these pathologies of developmental alterations of the superior olivary complex (SOC), a group of pontine nuclei likewise involved in hearing, prompted us to investigate whether the inferior colliculus may somehow contribute to the pathogenetic mechanism of unexplained perinatal death. Therefore, we performed in a wide set of fetuses and infants, aged from 33 gestational weeks to 7 postnatal months and died of both known and unknown cause, an in-depth anatomopathological analysis of the brainstem, particularly of the midbrain. Peculiar neuroanatomical and functional abnormalities of the inferior colliculus, such as hypoplasia/structural disarrangement and immunonegativity or poor positivity of serotonin, were exclusively found in sudden death victims, and not in controls. In addition, these alterations were frequently related to dysgenesis of connected structures, precisely the raphé nuclei and the superior olivary complex, and to nicotine absorption in pregnancy. We propose, on the basis of these results, the involvement of the inferior colliculus in more important functions than those related to hearing, as breathing and, more extensively, all the vital activities, and then in pathological conditions underlying a sudden death in vulnerable periods of the autonomic nervous system development, particularly associated to harmful risk factors as cigarette smoking. PMID:25674737

  2. Sensibility of grey particle production system to energy and centrality in 60A and 200A GeV 16O-Nucleus interactions

    NASA Astrophysics Data System (ADS)

    Abdelsalam, A.; El–Nagdy, M. S.; Badawy, B. M.; Osman, W.; Fayed, M.

    2016-06-01

    The grey particle production following 60 A and 200A GeV 16O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4π space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

  3. Sources of input to the rostromedial tegmental nucleus, ventral tegmental area, and lateral habenula compared: A study in rat.

    PubMed

    Yetnikoff, Leora; Cheng, Anita Y; Lavezzi, Heather N; Parsley, Kenneth P; Zahm, Daniel S

    2015-11-01

    Profound inhibitory control exerted on midbrain dopaminergic neurons by the lateral habenula (LHb), which has mainly excitatory outputs, is mediated by the GABAergic rostromedial tegmental nucleus (RMTg), which strongly innervates dopaminergic neurons in the ventral midbrain. Early reports indicated that the afferent connections of the RMTg, excepting its very strong LHb inputs, do not differ appreciably from those of the ventral tegmental area (VTA). Presumably, however, the RMTg contributes more to behavioral synthesis than to simply invert the valence of the excitatory signal coming from the LHb. Therefore, the present study was done to directly compare the inputs to the RMTg and VTA and, in deference to its substantial involvement with this circuitry, the LHb was also included in the comparison. Data indicated that, while the afferents of the RMTg, VTA, and LHb do originate within the same large pool of central nervous system (CNS) structures, each is also related to structures that project more strongly to it than to the others. The VTA gets robust input from ventral striatopallidum and extended amygdala, whereas RMTg biased inputs arise in structures with a more direct impact on motor function, such as deep layers of the contralateral superior colliculus, deep cerebellar and several brainstem nuclei, and, via a relay in the LHb, the entopeduncular nucleus. Input from the ventral pallidal-lateral preoptic-lateral hypothalamus continuum is strong in the RMTg and VTA and dominant in the LHb. Axon collateralization was also investigated, providing additional insights into the organization of the circuitry of this important triad of structures. PMID:25940654

  4. Demonstration of prosthetic activation of central auditory pathways using ( sup 14 C)-2-deoxyglucose

    SciTech Connect

    Evans, D.A.; Niparko, J.K.; Altschuler, R.A.; Frey, K.A.; Miller, J.M. )

    1990-02-01

    The cochlear prosthesis is not applicable to patients who lack an implantable cochlea or an intact vestibulocochlear nerve. Direct electrical stimulation of the cochlear nucleus (CN) of the brain stem might provide a method for auditory rehabilitation of these patients. A penetrating CN electrode has been developed and tissue tolerance to this device demonstrated. This study was undertaken to evaluate metabolic activation of central nervous system (CNS) auditory tracts produced by such implants. Regional cerebral glucose use resulting from CN stimulation was estimated in a series of chronically implanted guinea pigs with the use of ({sup 14}C)-2-deoxyglucose (2-DG). Enhanced 2-DG uptake was observed in structures of the auditory tract. The activation of central auditory structures achieved with CN stimulation was similar to that produced by acoustic stimulation and by electrical stimulation of the modiolar portion of the auditory nerve in control groups. An interesting banding pattern was observed in the inferior colliculus following CN stimulation, as previously described with acoustic stimulation. This study demonstrates that functional metabolic activation of central auditory pathways can be achieved with a penetrating CNS auditory prosthesis.

  5. Responses to Social Vocalizations in the Dorsal Cochlear Nucleus of Mice

    PubMed Central

    Roberts, Patrick D.; Portfors, Christine V.

    2015-01-01

    Identifying sounds is critical for an animal to make appropriate behavioral responses to environmental stimuli, including vocalizations from conspecifics. Identification of vocalizations may be supported by neuronal selectivity in the auditory pathway. The first place in the ascending auditory pathway where neuronal selectivity to vocalizations has been found is in the inferior colliculus (IC), but very few brainstem nuclei have been evaluated. Here, we tested whether selectivity to vocalizations is present in the dorsal cochlear nucleus (DCN). We recorded extracellular neural responses in the DCN of mice and found that fusiform cells responded in a heterogeneous and selective manner to mouse ultrasonic vocalizations. Most fusiform cells responded to vocalizations that contained spectral energy at much higher frequencies than the characteristic frequencies of the cells. To understand this mismatch of stimulus properties and frequency tuning of the cells, we developed a dynamic, nonlinear model of the cochlea that simulates cochlear distortion products on the basilar membrane. We preprocessed the vocalization stimuli through this model and compared responses to these distorted vocalizations with responses to the original vocalizations. We found that fusiform cells in the DCN respond in a heterogeneous manner to vocalizations, and that these neurons can use distortion products as a mechanism for encoding ultrasonic vocalizations. In addition, the selective neuronal responses were dependent on the presence of inhibitory sidebands that modulated the response depending on the temporal structure of the distortion product. These findings suggest that important processing of complex sounds occurs at a very early stage of central auditory processing and is not strictly a function of the cortex. PMID:26733824

  6. Functional connectivity between the superficial and deeper layers of the superior colliculus: an anatomical substrate for sensorimotor integration.

    PubMed

    Doubell, Timothy P; Skaliora, Irini; Baron, Jérôme; King, Andrew J

    2003-07-23

    The superior colliculus (SC) transforms both visual and nonvisual sensory signals into motor commands that control orienting behavior. Although the afferent and efferent connections of this midbrain nucleus have been well characterized, little is know about the intrinsic circuitry involved in sensorimotor integration. Transmission of visual signals from the superficial (sSC) to the deeper layers (dSC) of the SC has been implicated in both the triggering of orienting movements and the activity-dependent processes that align maps of different sensory modalities during development. However, evidence for the synaptic connectivity appropriate for these functions is lacking. In this study, we used a variety of anatomical and physiological methods to examine the functional organization of the sSC-dSC pathway in juvenile and adult ferrets. Axonal tracing in adult ferrets showed that, as in other species, sSC neurons project topographically to the dSC, providing a route for the transmission of visual signals to the multisensory output layers of the SC. We found that sSC axons terminate on dSC neurons that stain prominently for the NR1 subunit of the NMDA receptor, a subpopulation of which were identified as tectoreticulospinal projection neurons. We also show that the sSC-dSC pathway is topographically organized and mediated by monosynaptic excitatory synapses even before eye opening in young ferrets, suggesting that visual signals routed via the sSC may influence the activity of dSC neurons before the emergence of their multisensory response properties. These findings indicate that superficial- to deep-layer projections provide spatially ordered visual signals, both during development and into adulthood, directly to SC neurons that are involved in coordinating sensory inputs with motor outputs. PMID:12878701

  7. Retinal and Tectal “Driver-Like” Inputs Converge in the Shell of the Mouse Dorsal Lateral Geniculate Nucleus

    PubMed Central

    Zhou, Na; Krahe, Thomas E.; Govindaiah, Gubbi

    2015-01-01

    The dorsal lateral geniculate nucleus (dLGN) is a model system for understanding thalamic organization and the classification of inputs as “drivers” or “modulators.” Retinogeniculate terminals provide the primary excitatory drive for the relay of information to visual cortex (V1), while nonretinal inputs act in concert to modulate the gain of retinogeniculate signal transmission. How do inputs from the superior colliculus, a visuomotor structure, fit into this schema? Using a variety of anatomical, optogenetic, and in vitro physiological techniques in mice, we show that dLGN inputs from the superior colliculus (tectogeniculate) possess many of the ultrastructural and synaptic properties that define drivers. Tectogeniculate and retinogeniculate terminals converge to innervate one class of dLGN neurons within the dorsolateral shell, the primary terminal domain of direction-selective retinal ganglion cells. These dLGN neurons project to layer I of V1 to form synaptic contacts with dendrites of deeper-layer neurons. We suggest that tectogeniculate inputs act as “backseat drivers,” which may alert shell neurons to movement commands generated by the superior colliculus. SIGNIFICANCE STATEMENT The conventional view of the dorsal lateral geniculate nucleus (dLGN) is that of a simple relay of visual information between the retina and cortex. Here we show that the dLGN receives strong excitatory input from both the retina and the superior colliculus. Thus, the dLGN is part of a specialized visual channel that provides cortex with convergent information about stimulus motion and eye movement and positioning. PMID:26203147

  8. The dissimilar time course of temporary threshold shifts and reduction of inhibition in the inferior colliculus following intense sound exposure.

    PubMed

    Heeringa, A N; van Dijk, P

    2014-06-01

    Excessive noise exposure is known to produce an auditory threshold shift, which can be permanent or transient in nature. Recent studies showed that noise-induced temporary threshold shifts are associated with loss of synaptic connections to the inner hair cells and with cochlear nerve degeneration, which is reflected in a decreased amplitude of wave I of the auditory brainstem response (ABR). This suggests that, despite normal auditory thresholds, central auditory processing may be abnormal. We recorded changes in central auditory processing following a sound-induced temporary threshold shift. Anesthetized guinea pigs were exposed for 1 h to a pure tone of 11 kHz (124 dB sound pressure level). Hearing thresholds, amplitudes of ABR waves I and IV, and spontaneous and tone-evoked firing rates in the inferior colliculus (IC) were assessed immediately, one week, two weeks, and four weeks post exposure. Hearing thresholds were elevated immediately following overexposure, but recovered within one week. The amplitude of the ABR wave I was decreased in all sound-exposed animals for all test periods. In contrast, the ABR wave IV amplitude was only decreased immediately after overexposure and recovered within a week. The proportion of IC units that show inhibitory responses to pure tones decreased substantially up to two weeks after overexposure, especially when stimulated with high frequencies. The proportion of excitatory responses to low frequencies was increased. Spontaneous activity was unaffected by the overexposure. Despite rapid normalization of auditory thresholds, our results suggest an increased central gain following sound exposure and an abnormal balance between excitatory and inhibitory responses in the midbrain up to two weeks after overexposure. These findings may be associated with hyperacusis after a sound-induced temporary threshold shift. PMID:24650953

  9. High energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Wosiek, B.

    1986-01-01

    Experimental results on high energy nucleus-nucleus interactions are presented. The data are discussed within the framework of standard super-position models and from the point-of-view of the possible formation of new states of matter in heavy ion collisions.

  10. Transmissibility studies of vacuolar changes in the rostral colliculus of pigs

    PubMed Central

    Konold, Timm; Spiropoulos, John; Chaplin, Melanie J; Thorne, Leigh; Spencer, Yvonne I; Wells, Gerald AH; Hawkins, Steve AC

    2009-01-01

    Background Histopathological examinations of brains from healthy pigs have revealed localised vacuolar changes, predominantly in the rostral colliculus, that are similar to the neuropil vacuolation featured in the transmissible spongiform encephalopathies and have been described in pigs challenged parenterally with the agent causing bovine spongiform encephalopathy (BSE). Feedstuff containing BSE-contaminated meat and bone meal (MBM) may have been fed to pigs prior to the ban of mammalian MBM in feed of farmed livestock in the United Kingdom in 1996, but there is no evidence of the natural occurrence of a transmissible spongiform encephalopathy (TSE) in the domestic pig. Furthermore, experimental transmission of BSE to pigs by the oral route has been unsuccessful. A study was conducted to investigate whether the localised vacuolar changes in the porcine brain were associated with a transmissible aetiology and therefore biologically significant. Two groups of ten pigs were inoculated parenterally with vacuolated rostral colliculus from healthy pigs either born before 1996 or born after 1996. Controls included ten pigs similarly inoculated with rostral colliculus from New Zealand-derived pigs and nine pigs inoculated with a bovine BSE brain homogenate. Results None of the pigs inoculated with rostral colliculus developed a TSE-like neurological disease up to five years post inoculation when the study was terminated, and disease-associated prion protein, PrPd, was not detected in the brains of these pigs. By contrast, eight of nine BSE-inoculated pigs developed neurological signs, two of which had detectable PrPd by postmortem tests. No significant histopathological changes were detected to account for the clinical signs in the PrPd-negative, BSE-inoculated pigs. Conclusion The findings in this study suggest that vacuolation in the porcine rostral colliculus is not caused by a transmissible agent and is probably a clinically insignificant change. The presence of

  11. Dorsal raphe nucleus projecting retinal ganglion cells: Why Y cells?

    PubMed Central

    Pickard, Gary E.; So, Kwok-Fai; Pu, Mingliang

    2015-01-01

    Retinal ganglion Y (alpha) cells are found in retinas ranging from frogs to mice to primates. The highly conserved nature of the large, fast conducting retinal Y cell is a testament to its fundamental task, although precisely what this task is remained ill-defined. The recent discovery that Y-alpha retinal ganglion cells send axon collaterals to the serotonergic dorsal raphe nucleus (DRN) in addition to the lateral geniculate nucleus (LGN), medial interlaminar nucleus (MIN), pretectum and the superior colliculus (SC) has offered new insights into the important survival tasks performed by these cells with highly branched axons. We propose that in addition to its role in visual perception, the Y-alpha retinal ganglion cell provides concurrent signals via axon collaterals to the DRN, the major source of serotonergic afferents to the forebrain, to dramatically inhibit 5-HT activity during orientation or alerting/escape responses, which dis-facilitates ongoing tonic motor activity while dis-inhibiting sensory information processing throughout the visual system. The new data provide a fresh view of these evolutionarily old retinal ganglion cells. PMID:26363667

  12. Dorsal raphe nucleus projecting retinal ganglion cells: Why Y cells?

    PubMed

    Pickard, Gary E; So, Kwok-Fai; Pu, Mingliang

    2015-10-01

    Retinal ganglion Y (alpha) cells are found in retinas ranging from frogs to mice to primates. The highly conserved nature of the large, fast conducting retinal Y cell is a testament to its fundamental task, although precisely what this task is remained ill-defined. The recent discovery that Y-alpha retinal ganglion cells send axon collaterals to the serotonergic dorsal raphe nucleus (DRN) in addition to the lateral geniculate nucleus (LGN), medial interlaminar nucleus (MIN), pretectum and the superior colliculus (SC) has offered new insights into the important survival tasks performed by these cells with highly branched axons. We propose that in addition to its role in visual perception, the Y-alpha retinal ganglion cell provides concurrent signals via axon collaterals to the DRN, the major source of serotonergic afferents to the forebrain, to dramatically inhibit 5-HT activity during orientation or alerting/escape responses, which dis-facilitates ongoing tonic motor activity while dis-inhibiting sensory information processing throughout the visual system. The new data provide a fresh view of these evolutionarily old retinal ganglion cells. PMID:26363667

  13. Nucleus-nucleus scattering at high energies

    NASA Technical Reports Server (NTRS)

    Franco, V.; Varma, G. K.

    1977-01-01

    Nucleus-nucleus scattering is treated in the Glauber approximation. The usual optical limit result, generally thought to improve as the number of nucleons in the colliding nuclei increases, is found to be the first term of a series which diverges for large nuclei. Corrections to the optical limit are obtained which provide a means of performing realistic calculations for collisions involving light nuclei. Total cross section predictions agree well with recent measurements.

  14. Blockade of the GLT-1 Transporter in the Central Nucleus of the Amygdala Induces both Anxiety and Depressive-Like Symptoms

    PubMed Central

    John, Catherine S; Sypek, Elizabeth I; Carlezon, William A; Cohen, Bruce M; Öngür, Dost; Bechtholt, Anita J

    2015-01-01

    Depression has been associated with abnormalities in glutamatergic neurotransmission and decreased astrocyte number in limbic areas. We previously demonstrated that global and prefrontal cortical blockade of the astrocytic glutamate transporter (GLT-1) induces anhedonia and c-Fos expression in areas that regulate anxiety, including the central amygdala (CEA). Given the role of the amygdala in anxiety and the high degree of comorbidity between anxiety and depression, we hypothesized that GLT-1 blockade in the CEA would induce symptoms of anhedonia and anxiety in rats. We microinjected the GLT-1 inhibitor, dihydrokainic acid (DHK), into the CEA and examined effects on intracranial self-stimulation (ICSS) as an index of hedonic state, and on behavior in two anxiety paradigms, elevated plus maze (EPM) and fear conditioning. At lower doses, intra-CEA DHK produced modest increases in ICSS responding (T0). Higher doses resulted in complete cessation of responding for 15 min, suggesting an anhedonic or depressive-like effect. Intra-CEA DHK also increased anxiety-like behavior such that percent time in the open arms and total entries were decreased in the EPM and acquisition of freezing behavior to the tone was increased in a fear-conditioning paradigm. These effects did not appear to be explained by non-specific changes in activity, because effects on fear conditioning were assessed in a drug-free state, and a separate activity test showed no significant effects of intra-CEA DHK on locomotion. Taken together, these studies suggest that blockade of GLT-1 in the CEA is sufficient to induce both anhedonia and anxiety and therefore that a lack of glutamate uptake resulting from glial deficits may contribute to the comorbidity of depression and anxiety. PMID:25586634

  15. The Foxb1-expressing neurons of the ventrolateral hypothalamic parvafox nucleus project to defensive circuits.

    PubMed

    Bilella, Alessandro; Alvarez-Bolado, Gonzalo; Celio, Marco R

    2016-10-15

    The parvafox nucleus is an elongated structure that is lodged within the ventrolateral hypothalamus and lies along the optic tract. It comprises axially located parvalbumin (Parv)-positive neurons and a peripheral cuff of Foxb1-expressing ones. In the present study, injections of Cre-dependent adenoviral constructs were targeted to the ventrolateral hypothalamus of Foxb1/Cre mice to label specifically and map the efferent connections of the Foxb1-expressing subpopulation of neurons of the parvafox nucleus. These neurons project more widely than do the Parv-positive ones and implicate a part of the axons known to emanate from the lateral hypothalamus. High labeling densities were found in the dorsolateral and the upper lateral portion of the periaqueductal gray (PAG), the Su3 and PV2 nuclei of the ventrolateral PAG, the cuneiform nucleus, the mesencephalic reticular formation, and the superior colliculus. Intermediate densities of terminals were encountered in the septum, bed nucleus of the stria terminalis, substantia innominata, various thalamic and hypothalamic nuclei, pedunculopontine nucleus, Barrington's nucleus, retrofacial nucleus, and retroambigual nucleus. Scattered terminals were observed in the olfactory bulbs, the prefrontal cortex and the lamina X of the cervical spinal cord. Because the terminals were demonstrated to express the glutamate transporter VGlut2, the projections are presumed to be excitatory. A common denominator of the main target sites of the Foxb1-positive axons of the parvafox nucleus appears to be an involvement in the defensive reactions to life-threatening situations. The hypothalamic parvafox nucleus may contribute to the autonomic manifestations that accompany the expression of emotions. J. Comp. Neurol. 524:2955-2981, 2016. © 2016 Wiley Periodicals, Inc. PMID:27292133

  16. Regional and laminar distribution of cortical neurons projecting to either superior or inferior colliculus in the hedgehog tenrec.

    PubMed

    Künzle, H

    1995-01-01

    Retrograde tracer substances were injected into either the inferior or the superior colliculus in the Madagascan hedgehog tenrec, Echinops telfairi (Insectivora), to reveal the laminar and regional distribution of corticotectal cells and to correlate the labeled areas with architectural data. The tenrecs, taken from our breeding colony, have one of the least differentiated cerebral cortices among mammals, and experimental investigations of such brains are important for the understanding of the evolution and intrinsic organization of the more highly differentiated cerebral cortex in other placental mammals. Following injections into the inferior colliculus, cortical neurons were labeled bilaterally, with an ipsilateral predominance. Most labeled cells were found in the caudolateral hemisphere, area 4 as defined by Rehkämper (1981); some were in the somatosensorimotor cortex, as defined in a previous study. The labeled neurons in area 4 were located in layers V and VI, forming two bands of cells separated from each other by a poorly labeled interspace. A further subdivision of this presumed auditory region could not be achieved. This entire area was also weakly labeled following tracer injections into the superior colliculus. The labeled cells, however, were restricted to layer V of the ipsilateral side. The most consistent sites of labeled cells following injections into the superior colliculus were found in layer V of the ipsilateral caudomedial hemisphere, Rehkämper's caudal area 3, and the transitional zone adjacent to the retrosplenial cortex. This area is small in comparison to the entire region that was found in this study to project to the superior colliculus. The superior colliculus also receives projections from the ipsilateral sensorimotor and cingulate cortices. The latter projections are particularly striking in comparison to other mammals because they originate from along the entire rostrocaudal extent of the cingulate/retrosplenial region. PMID

  17. Modification of visual response properties in the superior colliculus of the golden hamster following stroboscopic rearing

    PubMed Central

    Chalupa, Leo M.; Rhoades, Robert W.

    1978-01-01

    1. Visual response properties of superior collicular neurones were investigated in golden hamsters reared from birth to adulthood in a stroboscopic environment. 2. In comparison to normally reared animals, there was a marked decrease in the incidence of directionally selective cells in the colliculus of the strobe-reared hamsters. This effect was apparent when directional selectivity was determined by either the null criterion or a statistical measure. The reduction in directionally selective cells was found in both superficial and the deep layers of the colliculus. 3. Neurones in strobe-reared hamsters also exhibited a different speed preference distribution from that obtained for normal animals, in that more cells in the restricted hamsters responded only to slow velocities, and less were broadly tuned with regard to the speed of moving stimuli. 4. In addition to the effects obtained in dynamic response properties, there were also changes in the static response properties of superior collicular neurones. These were an increase in the proportion of cells whose responses were not affected by changing the size of a stationary flashed stimulus, and a concomitant decrease in the number of cells demonstrating either partial or complete suppression when the size of a flashed stimulus exceeded the boundaries of the receptive field activating region. Furthermore, while all cells which responded to stationary stimuli in normal animals yielded only phasic responses to stimulus onset and/or offset, in the strobe-reared hamsters eight cells were encountered which responded in a sustained fashion to stationary spots. 5. There was no indication of an increased responsivity in the restricted animals to strobe stimulation, even when a strobe rate identical to that employed in the rearing environment was employed. 6. The results were interpreted as indicating a disruption of normal visual functional organization in the hamster's superior colliculus by an aberrant visual input

  18. Role of the Primate Superior Colliculus in the Control of Head Movements

    PubMed Central

    Walton, Mark M. G.; Bechara, Bernard; Gandhi, Neeraj J.

    2013-01-01

    One important behavioral role for head movements is to assist in the redirection of gaze. However, primates also frequently make head movements that do not involve changes in the line of sight. Virtually nothing is known about the neural basis of these head-only movements. In the present study, single-unit extracellular activity was recorded from the superior colliculus while monkeys performed behavioral tasks that permit the temporal dissociation of gaze shifts and head movements. We sought to determine whether superior colliculus contains neurons that modulate their activity in association with head movements in the absence of gaze shifts and whether classic gaze-related burst neurons also discharge for head-only movements. For 26% of the neurons in our sample, significant changes in average firing rate could be attributed to head-only movements. Most of these increased their firing rate immediately prior to the onset of a head movement and continued to discharge at elevated frequency until the offset of the movement. Others discharged at a tonic rate when the head was stable and decreased their activity, or paused, during head movements. For many putative head cells, average firing rate was found to be predictive of head displacement. Some neurons exhibited significant changes in activity associated with gaze, eye-only, and head-only movements, although none of the gaze-related burst neurons significantly modulated its activity in association with head-only movements. These results suggest the possibility that the superior colliculus plays a role in the control of head movements independent of gaze shifts. PMID:17581848

  19. Microinfusion of pituitary adenylate cyclase-activating polypeptide into the central nucleus of amygdala of the rat produces a shift from an active to passive mode of coping in the shock-probe fear/defensive burying test.

    PubMed

    Legradi, Gabor; Das, Mahasweta; Giunta, Brian; Hirani, Khemraj; Mitchell, E Alice; Diamond, David M

    2007-01-01

    High concentrations of pituitary adenylate cyclase-activating polypeptide (PACAP) nerve fibers are present in the central nucleus of amygdala (CeA), a brain region implicated in the control of fear-related behavior. This study evaluated PACAPergic modulation of fear responses at the CeA in male Sprague-Dawley rats. PACAP (50-100 pmol) microinfusion via intra-CeA cannulae produced increases in immobility and time the rats spent withdrawn into a corner opposite to the electrified probe compared to controls in the shock-probe fear/defensive burying test. Shock-probe burying and exploration, numbers of shocks received, locomotion distance, and velocity were all reduced by intra-CeA PACAP injection. Further, intra-CeA PACAP effects were manifested only when the animals were challenged by shock, as intra-CeA PACAP injections did not cause significant changes in the behaviors of unshocked rats. Thus, intra-CeA administration of PACAP produces a distinct reorganization of stress-coping behaviors from active (burying) to passive modes, such as withdrawal and immobility. These findings are potentially significant toward enhancing our understanding of the involvement of PACAP and the CeA in the neural basis of fear and anxiety. PMID:17641738

  20. Role of amygdala central nucleus in the potentiation of consuming and instrumental lever-pressing for sucrose by cues for the presentation or interruption of sucrose delivery in rats

    PubMed Central

    Holland, Peter C.; Hsu, Melanie

    2014-01-01

    Initially neutral conditioned stimuli (CSs) paired with food often acquire motivating properties. For example, CS presentations may enhance the rate of instrumental responding that normally earns that food reward (Pavlovian-instrumental transfer), or potentiate consumption of that food when the animal is food-sated. Recent evidence suggests that cues associated with the withdrawal of food and food cues (interruption stimuli or ISs) may also potentiate feeding, despite exhibiting some characteristics of conditioned inhibition. Here, we compared the ability of CSs and ISs to modulate both eating food and working for it. If CSs and ISs potentiate eating food by controlling a similar incentive state, both types of cues might also be expected to enhance instrumental responding for food. Although we found substantial potentiation of feeding by both CSs and ISs, and powerful enhancement of instrumental responding by a CS, we found no evidence for such instrumental enhancement by an IS. Furthermore, although an IS produced more FOS expression in the amygdala central nucleus (CeA) than either a previously reinforced CS or a control stimulus after a test for potentiated feeding, an intact CeA was unnecessary for potentiation of feeding by either a CS or an IS. Nevertheless, as in previous studies, CeA was critical to the ability of a CS to enhance instrumental responding. Implications for understanding the nature and basis for incentive learning are discussed. PMID:24512067

  1. Retinal ganglion cell projections to the hamster suprachiasmatic nucleus, intergeniculate leaflet, and visual midbrain: bifurcation and melanopsin immunoreactivity

    NASA Technical Reports Server (NTRS)

    Morin, Lawrence P.; Blanchard, Jane H.; Provencio, Ignacio

    2003-01-01

    The circadian clock in the suprachiasmatic nucleus (SCN) receives direct retinal input via the retinohypothalamic tract (RHT), and the retinal ganglion cells contributing to this projection may be specialized with respect to direct regulation of the circadian clock. However, some ganglion cells forming the RHT bifurcate, sending axon collaterals to the intergeniculate leaflet (IGL) through which light has secondary access to the circadian clock. The present studies provide a more extensive examination of ganglion cell bifurcation and evaluate whether ganglion cells projecting to several subcortical visual nuclei contain melanopsin, a putative ganglion cell photopigment. The results showed that retinal ganglion cells projecting to the SCN send collaterals to the IGL, olivary pretectal nucleus, and superior colliculus, among other places. Melanopsin-immunoreactive (IR) ganglion cells are present in the hamster retina, and some of these cells project to the SCN, IGL, olivary pretectal nucleus, or superior colliculus. Triple-label analysis showed that melanopsin-IR cells bifurcate and project bilaterally to each SCN, but not to the other visual nuclei evaluated. The melanopsin-IR cells have photoreceptive characteristics optimal for circadian rhythm regulation. However, the presence of moderately widespread bifurcation among ganglion cells projecting to the SCN, and projection by melanopsin-IR cells to locations distinct from the SCN and without known rhythm function, suggest that this ganglion cell type is generalized, rather than specialized, with respect to the conveyance of photic information to the brain. Copyright 2003 Wiley-Liss, Inc.

  2. Serotonin modulates responses to species-specific vocalizations in the inferior colliculus.

    PubMed

    Hurley, Laura M; Pollak, George D

    2005-06-01

    Neuromodulators such as serotonin are capable of altering the neural processing of stimuli across many sensory modalities. In the inferior colliculus, a major midbrain auditory gateway, serotonin alters the way that individual neurons respond to simple tone bursts and linear frequency modulated sweeps. The effects of serotonin are complex, and vary among neurons. How serotonin transforms the responses to spectrotemporally complex sounds of the type normally heard in natural settings has been poorly examined. To explore this issue further, the effects of iontophoretically applied serotonin on the responses of individual inferior colliculus neurons to a variety of recorded species-specific vocalizations were examined. These experiments were performed in the Mexican free-tailed bat, a species that uses a rich repertoire of vocalizations for the purposes of communication as well as echolocation. Serotonin frequently changed the number of recorded calls that were capable of evoking a response from individual neurons, sometimes increasing (15% of serotonin-responsive neurons), but usually decreasing (62% of serotonin-responsive neurons), this number. A functional consequence of these serotonin-evoked changes would be to change the population response to species-specific vocalizations. PMID:15830241

  3. Dopamine D2-Like Receptors Modulate Unconditioned Fear: Role of the Inferior Colliculus

    PubMed Central

    de Oliveira, Amanda Ribeiro; Colombo, Ana Caroline; Muthuraju, Sangu; Almada, Rafael Carvalho; Brandão, Marcus Lira

    2014-01-01

    Background A reduction of dopamine release or D2 receptor blockade in the terminal fields of the mesolimbic system clearly reduces conditioned fear. Injections of haloperidol, a preferential D2 receptor antagonist, into the inferior colliculus (IC) enhance the processing of unconditioned aversive information. However, a clear characterization of the interplay of D2 receptors in the mediation of unconditioned and conditioned fear is still lacking. Methods The present study investigated the effects of intra-IC injections of the D2 receptor-selective antagonist sulpiride on behavior in the elevated plus maze (EPM), auditory-evoked potentials (AEPs) to loud sounds recorded from the IC, fear-potentiated startle (FPS), and conditioned freezing. Results Intra-IC injections of sulpiride caused clear proaversive effects in the EPM and enhanced AEPs induced by loud auditory stimuli. Intra-IC sulpiride administration did not affect FPS or conditioned freezing. Conclusions Dopamine D2-like receptors of the inferior colliculus play a role in the modulation of unconditioned aversive information but not in the fear-potentiated startle response. PMID:25133693

  4. Modeling the Minimal Newborn's Intersubjective Mind: The Visuotopic-Somatotopic Alignment Hypothesis in the Superior Colliculus

    PubMed Central

    Pitti, Alexandre; Kuniyoshi, Yasuo; Quoy, Mathias; Gaussier, Philippe

    2013-01-01

    The question whether newborns possess inborn social skills is a long debate in developmental psychology. Fetal behavioral and anatomical observations show evidences for the control of eye movements and facial behaviors during the third trimester of pregnancy whereas specific sub-cortical areas, like the superior colliculus (SC) and the striatum appear to be functionally mature to support these behaviors. These observations suggest that the newborn is potentially mature for developing minimal social skills. In this manuscript, we propose that the mechanism of sensory alignment observed in SC is particularly important for enabling the social skills observed at birth such as facial preference and facial mimicry. In a computational simulation of the maturing superior colliculus connected to a simulated facial tissue of a fetus, we model how the incoming tactile information is used to direct visual attention toward faces. We suggest that the unisensory superficial visual layer (eye-centered) and the deep somatopic layer (face-centered) in SC are combined into an intermediate layer for visuo-tactile integration and that multimodal alignment in this third layer allows newborns to have a sensitivity to configuration of eyes and mouth. We show that the visual and tactile maps align through a Hebbian learning stage and and strengthen their synaptic links from each other into the intermediate layer. It results that the global network produces some emergent properties such as sensitivity toward the spatial configuration of face-like patterns and the detection of eyes and mouth movement. PMID:23922718

  5. Spectral integration in the inferior colliculus: role of glycinergic inhibition in response facilitation.

    PubMed

    Wenstrup, J; Leroy, S A

    2001-02-01

    This study examined the contribution of glycinergic inhibition to the time-sensitive spectral integration performed by neurons in the inferior colliculus of the mustached bat (Pteronotus parnellii). These neurons are sometimes called combination-sensitive because they display facilitatory (or inhibitory) responses to the combination of distinct spectral elements in sonar or social vocalizations. Present in a wide range of vertebrates, their temporally and spectrally selective integration is thought to endow them with the ability to discriminate among social vocalizations or to analyze particular cues concerning sonar targets. The mechanisms that underlie these responses or the sites in the auditory system where they are created are not known. We examined combination-sensitive neurons that are facilitated by the presentation of two different harmonic elements of the bat's sonar call and echo. Responses of 24 single units were recorded before and during local application of strychnine, an antagonist of glycinergic inhibition. For each of the 24 units, strychnine application eliminated or greatly reduced temporally sensitive facilitation. There was no difference in this effect for neurons tuned to frequencies associated with the frequency-modulated or the constant-frequency sonar components. These results are unusual because glycine is considered to be an inhibitory neurotransmitter, but here it appears to be essential for the expression of combination-sensitive facilitation. The findings provide strong evidence that facilitatory combination-sensitive response properties present throughout the mustached bat's auditory midbrain, thalamus, and cortex originate through neural interactions in the inferior colliculus. PMID:11157095

  6. Modeling the minimal newborn's intersubjective mind: the visuotopic-somatotopic alignment hypothesis in the superior colliculus.

    PubMed

    Pitti, Alexandre; Kuniyoshi, Yasuo; Quoy, Mathias; Gaussier, Philippe

    2013-01-01

    The question whether newborns possess inborn social skills is a long debate in developmental psychology. Fetal behavioral and anatomical observations show evidences for the control of eye movements and facial behaviors during the third trimester of pregnancy whereas specific sub-cortical areas, like the superior colliculus (SC) and the striatum appear to be functionally mature to support these behaviors. These observations suggest that the newborn is potentially mature for developing minimal social skills. In this manuscript, we propose that the mechanism of sensory alignment observed in SC is particularly important for enabling the social skills observed at birth such as facial preference and facial mimicry. In a computational simulation of the maturing superior colliculus connected to a simulated facial tissue of a fetus, we model how the incoming tactile information is used to direct visual attention toward faces. We suggest that the unisensory superficial visual layer (eye-centered) and the deep somatopic layer (face-centered) in SC are combined into an intermediate layer for visuo-tactile integration and that multimodal alignment in this third layer allows newborns to have a sensitivity to configuration of eyes and mouth. We show that the visual and tactile maps align through a Hebbian learning stage and and strengthen their synaptic links from each other into the intermediate layer. It results that the global network produces some emergent properties such as sensitivity toward the spatial configuration of face-like patterns and the detection of eyes and mouth movement. PMID:23922718

  7. Spatial synchronization of visual stimulus-evoked gamma frequency oscillations in the rat superior colliculus.

    PubMed

    Baranauskas, Gytis; Svirskis, Gytis; Tkatch, Tatiana

    2016-02-10

    In the superior colliculus, visual stimuli can induce gamma frequency oscillations of neuronal activity. It has been shown that in cats, these oscillations are synchronized over distances of greater than 300 μm that may contribute toward visual information processing. We investigated the spatial properties of such oscillations in a rodent because the availability of molecular tools could enable future studies on the role of these oscillations in visual information processing. Using extracellular electrode array recordings in anesthetized rats, we found that visual stimuli-induced gamma and eta frequency (30-115 Hz) oscillations of the local field potential that were synchronized over distances of ∼ 600 μm. Multiple-unit events were phase locked to the local field potential signal and showed prominent oscillations during OFF responses. The rate of lower than 5 ms cross-electrode coincidences was in line with the response-corrected predictions for each electrode. These data suggest that the synchronized superior colliculus neuronal activity is largely network driven, whereas common synaptic inputs play a minor role. PMID:26735701

  8. Biomimetic race model of the loop between the superior colliculus and the basal ganglia: Subcortical selection of saccade targets.

    PubMed

    Thurat, Charles; N'Guyen, Steve; Girard, Benoît

    2015-07-01

    The superior colliculus, a laminar structure involved in the retinotopic mapping of the visual field, plays a cardinal role in several cortical and subcortical pathways of the saccadic system. Although the selection of saccade targets has long been thought to be mainly the product of cortical processes, a growing body of evidence hints at the implication of the superior colliculus in selection processes independent from cortical inputs, capable of producing saccades at latencies incompatible with the cortical pathways. This selection ability could be produced firstly by the lateral connections between the neurons of its maps, and secondly by its interactions with the midbrain basal ganglia, already renowned for their role in decision making. We propose a biomimetic population-coded race model of selection based on a dynamic tecto-basal loop that reproduces the observed ability of the superior colliculus to stochastically select between similar stimuli. Our model's selection accuracy depends on the discriminability of the target and the distractors. Our model also offers an explanation for the phenomenon of Remote Distractor Effect based on the lateral connectivity within the basal ganglia circuitry rather than on lateral inhibitions within the collicular maps. Finally, we propose a role for the intermediate layers of the superior colliculus, as stochastic integrators dynamically gated by the selective disinhibition of the basal ganglia channels that is consistent with the recorded activity profiles of these neurons. PMID:25884111

  9. ELECTROPHYSIOLOGICAL AND MORPHOLOGICAL EVIDENCE FOR A DIAMETER-BASED INNERVATION PATTERN OF THE SUPERIOR COLLICULUS (JOURNAL VERSION)

    EPA Science Inventory

    Neurophysiological and morphological techniques were used to describe changes in the optic tract and superior colliculus (SC) in response to monocular enucleation. Long-Evans, male, (250g) rats were implanted with chronic bipolar stimulating electrodes located in the optic chiasm...

  10. Decrease and conquer: Phacoemulsification technique for hard nucleus cataracts.

    PubMed

    Kim, Hong Kyun

    2009-10-01

    I describe a technique to improve the control and safety of phacoemulsification during hard nucleus cataract surgery. Whereas the goal of the conventional nucleofractis technique is complete fragmentation of the lens, the technique aims to separate the endonuclear core from the epinucleus. This is done in 3 steps: circumferential disassembly, decreasing the central nucleus volume, and conquering the remnant. The technique offers safer and more effective phacoemulsification in patients with hard nucleus cataracts. PMID:19781457

  11. Nucleus-nucleus interactions between 20 and 65 GeV per nucleon

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Derrickson, J. H.; Fountain, W. F.; Meegan, C. A.; Parnell, T. A.; Roberts, F. E.; Watts, J. W.; Oda, H.; Takahashi, Y.; Jones, W. V.

    1987-01-01

    A hybrid electronic-counter/emulsion-chamber instrument was exposed to high-energy cosmic rays on a balloon. The data on 105 nucleus-nucleus collisions in the energy range 20-65 GeV/nucleon and for incident nuclear charges Zp in the range of 22 to 28 are presented. Inclusive characteristics of particle production on different targets (plastic, emulsion, and lead) are shown and compared with models based on the superposition of nucleon-nucleus interactions. Features of a subset of the more central collisions with a plastic target and some characteristics of individual events with the highest multiplicity of produced particles are described.

  12. Restoration of quinine-stimulated Fos-immunoreactive neurons in the central nucleus of the amygdala and gustatory cortex following reinnervation or cross-reinnervation of the lingual taste nerves in rats

    PubMed Central

    King, Camille Tessitore; Garcea, Mircea; Spector, Alan C.

    2014-01-01

    Remarkably, when lingual gustatory nerves are surgically re-routed to inappropriate taste fields in the tongue, some taste functions recover. We previously demonstrated that quinine-stimulated oromotor rejection reflexes and neural activity (assessed by Fos-immunoreactivity) in subregions of hindbrain gustatory nuclei were restored if the posterior tongue, which contains receptor cells that respond strongly to bitter compounds, was cross-reinnervated by the chorda tympani nerve. Such functional recovery was not seen if instead, the anterior tongue, where receptor cells are less responsive to bitter compounds, was cross-reinnervated by the glossopharyngeal nerve, despite that this nerve typically responds robustly to bitter substances. Thus, recovery depended more on the taste field being reinnervated than on the nerve itself. Here, the distribution of quinine-stimulated Fos-immunoreactive neurons in two taste-associated forebrain areas was examined in these same rats. In the central nucleus of the amygdala (CeA), a rostrocaudal gradient characterized the normal quinine-stimulated Fos response, with the greatest number of labeled cells rostrally situated. Quinine-stimulated neurons were found throughout the gustatory cortex but a ‘hot spot’ was observed in its anterior-posterior center in subregions approximating the dysgranular/agranular layers. Fos neurons here and in the rostral CeA were highly correlated with quinine-elicited gapes. Denervation of the posterior tongue eliminated, and its reinnervation by either nerve restored, numbers of quinine-stimulated labeled cells in the rostral-most CeA and in the subregion approximating dysgranular gustatory cortex. These results underscore the remarkable plasticity of the gustatory system and also help clarify the functional anatomy of neural circuits activated by bitter taste stimulation. PMID:24477770

  13. Nucleon-nucleus interactions from JACEE

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1985-01-01

    Results on hadron-nucleus interactions from the Japanese-American Cooperation Emulsion Experiment experiment are presented. Angular distributions for charged particles, and angular and transverse momentum spectra for photons have been measured for a sample of events with sigma epsilon sub gamma. Results on central rapidity density and transverse energy flow are discussed.

  14. Role of the superior colliculus in choosing mixed-strategy saccades.

    PubMed

    Thevarajah, Dhushan; Mikulić, Areh; Dorris, Michael C

    2009-02-18

    Game theory outlines optimal response strategies during mixed-strategy competitions. The neural processes involved in choosing individual strategic actions, however, remain poorly understood. Here, we tested whether the superior colliculus (SC), a brain region critical for generating sensory-guided saccades, is also involved in choosing saccades under strategic conditions. Monkeys were free to choose either of two saccade targets as they competed against a computer opponent during the mixed-strategy game "matching pennies." The accuracy with which presaccadic SC activity predicted upcoming choice gradually increased in the time leading up to the saccade. Probing the SC with suprathreshold stimulation demonstrated that these evolving signals were functionally involved in preparing strategic saccades. Finally, subthreshold stimulation of the SC increased the likelihood that contralateral saccades were selected. Together, our results suggest that motor regions of the brain play an active role in choosing strategic actions rather than passively executing those prespecified by upstream executive regions. PMID:19228954

  15. GABAA-Mediated Inhibition Modulates Stimulus-Specific Adaptation in the Inferior Colliculus

    PubMed Central

    Pérez-González, David; Hernández, Olga; Covey, Ellen; Malmierca, Manuel S.

    2012-01-01

    The ability to detect novel sounds in a complex acoustic context is crucial for survival. Neurons from midbrain through cortical levels adapt to repetitive stimuli, while maintaining responsiveness to rare stimuli, a phenomenon called stimulus-specific adaptation (SSA). The site of origin and mechanism of SSA are currently unknown. We used microiontophoretic application of gabazine to examine the role of GABAA-mediated inhibition in SSA in the inferior colliculus, the midbrain center for auditory processing. We found that gabazine slowed down the process of adaptation to high probability stimuli but did not abolish it, with response magnitude and latency still depending on the probability of the stimulus. Blocking GABAA receptors increased the firing rate to high and low probability stimuli, but did not completely equalize the responses. Together, these findings suggest that GABAA-mediated inhibition acts as a gain control mechanism that enhances SSA by modifying the responsiveness of the neuron. PMID:22479591

  16. Auditory cortex controls sound-driven innate defense behaviour through corticofugal projections to inferior colliculus

    PubMed Central

    Xiong, Xiaorui R.; Liang, Feixue; Zingg, Brian; Ji, Xu-ying; Ibrahim, Leena A.; Tao, Huizhong W.; Zhang, Li I.

    2015-01-01

    Defense against environmental threats is essential for animal survival. However, the neural circuits responsible for transforming unconditioned sensory stimuli and generating defensive behaviours remain largely unclear. Here, we show that corticofugal neurons in the auditory cortex (ACx) targeting the inferior colliculus (IC) mediate an innate, sound-induced flight behaviour. Optogenetic activation of these neurons, or their projection terminals in the IC, is sufficient for initiating flight responses, while the inhibition of these projections reduces sound-induced flight responses. Corticocollicular axons monosynaptically innervate neurons in the cortex of the IC (ICx), and optogenetic activation of the projections from the ICx to the dorsal periaqueductal gray is sufficient for provoking flight behaviours. Our results suggest that ACx can both amplify innate acoustic-motor responses and directly drive flight behaviours in the absence of sound input through corticocollicular projections to ICx. Such corticofugal control may be a general feature of innate defense circuits across sensory modalities. PMID:26068082

  17. Neural interactions in unilateral colliculus and between bilateral colliculi modulate auditory signal processing

    PubMed Central

    Mei, Hui-Xian; Cheng, Liang; Chen, Qi-Cai

    2013-01-01

    In the auditory pathway, the inferior colliculus (IC) is a major center for temporal and spectral integration of auditory information. There are widespread neural interactions in unilateral (one) IC and between bilateral (two) ICs that could modulate auditory signal processing such as the amplitude and frequency selectivity of IC neurons. These neural interactions are either inhibitory or excitatory, and are mostly mediated by γ-aminobutyric acid (GABA) and glutamate, respectively. However, the majority of interactions are inhibitory while excitatory interactions are in the minority. Such unbalanced properties between excitatory and inhibitory projections have an important role in the formation of unilateral auditory dominance and sound location, and the neural interaction in one IC and between two ICs provide an adjustable and plastic modulation pattern for auditory signal processing. PMID:23626523

  18. Evidence for a neurotransmitter function of acetylcholine in rabbit superior colliculus.

    PubMed

    Wichmann, T; Illing, R B; Starke, K

    1987-12-01

    Acetylcholinesterase staining and studies on the uptake of [3H]choline into the subsequent efflux of tritium from collicular slices were carried out in order to provide evidence for a neurotransmitter function of acetylcholine in rabbit superior colliculus. Acetylcholinesterase staining was dense and homogeneous in superficial layers whereas the staining was arranged in patches with slightly higher density caudally than rostrally in the intermediate layers. The accumulation of tritium in slices incubated with [3H]choline depended on time, temperature and concentration, and was inhibited by hemicholinium-3. Accumulation was slightly higher in caudal than in rostral slices. Electrical stimulation enhanced tritium outflow from slices preincubated with [3H]choline. Tetrodotoxin and a low calcium medium inhibited the evoked overflow whereas hemicholinium-3 caused an enhancement. Oxotremorine decreased the evoked overflow; atropine prevented this effect. The opioids [D-Ala2, MePhe4, Glycol5]enkephalin, [D-Ala2, D-Leu5]enkephalin and ethylketocyclazocine caused an inhibition. The effects of the latter two agonists were antagonized by naloxone. The GABAB-receptor-agonist (-)-baclofen decreased the evoked overflow at lower concentrations than GABA, whereas the GABAA-receptor-agonist muscimol was ineffective. Serotonin produced an inhibition which was prevented by metitepin, alpha- and beta-adrenoceptor as well as dopamine-receptor ligands caused no change. It is concluded that in the rabbit superior colliculus the pattern of acetylcholinesterase staining is comparable, but not identical to the distribution in other species. The accumulation of [3H]choline, as well as the tetrodotoxin-sensitive and calcium-dependent overflow of tritium upon electrical stimulation (reflecting presumably release of [3H]acetylcholine) indicate that acetylcholine has a neurotransmitter function in this tissue. The release of [3H]acetylcholine was modulated by various transmitter substances and

  19. THE INFLUENCE OF VIBRISSAL SOMATOSENSORY PROCESSING IN RAT SUPERIOR COLLICULUS ON PREY CAPTURE

    PubMed Central

    FAVARO, P. D. N.; GOUVÊA, T. S.; DE OLIVEIRA, S. R.; VAUTRELLE, N.; REDGRAVE, P.; COMOLI, E.

    2011-01-01

    The lateral part of intermediate layer of superior colliculus (SCl) is a critical substrate for successful predation by rats. Hunting-evoked expression of the activity marker Fos is concentrated in SCl while prey capture in rats with NMDA lesions in SCl is impaired. Particularly affected are rapid orienting and stereotyped sequences of actions associated with predation of fast moving prey. Such deficits are consistent with the view that the deep layers of SC are important for sensory guidance of movement. Although much of the relevant evidence involves visual control of movement, less is known about movement guidance by somatosensory input from vibrissae. Indeed, our impression is that prey contact with whiskers is a likely stimulus to trigger predation. Moreover, SCl receives whisker and orofacial somatosensory information directly from trigeminal complex, and indirectly from zona incerta, parvicelular reticular formation and somatosensory barrel cortex. To better understand sensory guidance of predation by vibrissal information we investigated prey capture by rats after whisker removal and the role of superior colliculus (SC) by comparing Fos expression after hunting with and without whiskers. Rats were allowed to hunt cockroaches, after which their whiskers were removed. Two days later they were allowed to hunt cockroaches again. Without whiskers the rats were less able to retain the cockroaches after capture and less able to pursue them in the event of the cockroach escaping. The predatory behaviour of rats with re-grown whiskers returned to normal. In parallel, Fos expression in SCl induced by predation was significantly reduced in whiskerless animals. We conclude that whiskers contribute to the efficiency of rat prey capture and that the loss of vibrissal input to SCl, as reflected by reduced Fos expression, could play a critical role in predatory deficits of whiskerless rats. PMID:21163336

  20. Deactivation of the inferior colliculus by cooling demonstrates intercollicular modulation of neuronal activity

    PubMed Central

    Orton, Llwyd D.; Poon, Paul W. F.; Rees, Adrian

    2012-01-01

    The auditory pathways coursing through the brainstem are organized bilaterally in mirror image about the midline and at several levels the two sides are interconnected. One of the most prominent points of interconnection is the commissure of the inferior colliculus (CoIC). Anatomical studies have revealed that these fibers make reciprocal connections which follow the tonotopic organization of the inferior colliculus (IC), and that the commissure contains both excitatory and, albeit fewer, inhibitory fibers. The role of these connections in sound processing is largely unknown. Here we describe a method to address this question in the anaesthetized guinea pig. We used a cryoloop placed on one IC to produce reversible deactivation while recording electrophysiological responses to sounds in both ICs. We recorded single units, multi-unit clusters and local field potentials (LFPs) before, during and after cooling. The degree and spread of cooling was measured with a thermocouple placed in the IC and other auditory structures. Cooling sufficient to eliminate firing was restricted to the IC contacted by the cryoloop. The temperature of other auditory brainstem structures, including the contralateral IC and the cochlea were minimally affected. Cooling below 20°C reduced or eliminated the firing of action potentials in frequency laminae at depths corresponding to characteristic frequencies up to ~8 kHz. Modulation of neural activity also occurred in the un-cooled IC with changes in single unit firing and LFPs. Components of LFPs signaling lemniscal afferent input to the IC showed little change in amplitude or latency with cooling, whereas the later components, which likely reflect inter- and intra-collicular processing, showed marked changes in form and amplitude. We conclude that the cryoloop is an effective method of selectively deactivating one IC in guinea pig, and demonstrate that auditory processing in the IC is strongly influenced by the other. PMID:23248587

  1. Volumes of cochlear nucleus regions in rodents.

    PubMed

    Godfrey, Donald A; Lee, Augustine C; Hamilton, Walter D; Benjamin, Louis C; Vishwanath, Shilpa; Simo, Hermann; Godfrey, Lynn M; Mustapha, Abdurrahman I A A; Heffner, Rickye S

    2016-09-01

    The cochlear nucleus receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system. As such, it is a critical auditory nucleus. The sizes of the cochlear nucleus as a whole and its three major subdivisions - anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN) - have been measured in a large number of mammals, but measurements of its subregions at a more detailed level for a variety of species have not previously been made. Size measurements are reported here for the summed granular regions, DCN layers, AVCN, PVCN, and interstitial nucleus in 15 different rodent species, as well as a lagomorph, carnivore, and small primate. This further refinement of measurements is important because the granular regions and superficial layers of the DCN appear to have some different functions than the other cochlear nucleus regions. Except for DCN layers in the mountain beaver, all regions were clearly identifiable in all the animals studied. Relative regional size differences among most of the rodents, and even the 3 non-rodents, were not large and did not show a consistent relation to their wide range of lifestyles and hearing parameters. However, the mountain beaver, and to a lesser extent the pocket gopher, two rodents that live in tunnel systems, had relative sizes of summed granular regions and DCN molecular layer distinctly larger than those of the other mammals. Among all the mammals studied, there was a high correlation between the size per body weight of summed granular regions and that of the DCN molecular layer, consistent with other evidence for a close relationship between granule cells and superficial DCN neurons. PMID:27435005

  2. The Nucleus Introduced

    PubMed Central

    Pederson, Thoru

    2011-01-01

    Now is an opportune moment to address the confluence of cell biological form and function that is the nucleus. Its arrival is especially timely because the recognition that the nucleus is extremely dynamic has now been solidly established as a paradigm shift over the past two decades, and also because we now see on the horizon numerous ways in which organization itself, including gene location and possibly self-organizing bodies, underlies nuclear functions. PMID:20660024

  3. Uncovering the Nucleus Candidate for NGC 253

    NASA Astrophysics Data System (ADS)

    Günthardt, G. I.; Agüero, M. P.; Camperi, J. A.; Díaz, R. J.; Gomez, P. L.; Bosch, G.; Schirmer, M.

    2015-11-01

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H2 rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  4. Capsaicin-evoked brain activation and central sensitization in anaesthetised rats: a functional magnetic resonance imaging study.

    PubMed

    Moylan Governo, Ricardo Jose; Morris, Peter Gordon; Prior, Malcolm John William; Marsden, Charles Alexander; Chapman, Victoria

    2006-12-15

    Functional magnetic resonance imaging (fMRI) of blood oxygen level dependent (BOLD) haemodynamic responses was used to study the effects of the noxious substance capsaicin on whole brain activation in isofluorane anaesthetised rats. Rats (n=8) received intradermal injection of capsaicin (30 microg/5 microl), or topical cream (0.1%) capsaicin and BOLD responses were acquired for up to 120 min. Effects of capsaicin versus placebo cream treatment on the BOLD response to a 15 g mechanical stimulus applied adjacent to the site of cream application were also studied. Both injection and cream application of capsaicin activated brain areas involved in pain processing, including the thalamus and periaqueductal grey (PAG) (p<0.05, corrected for multiple comparisons). Capsaicin also produced increases in BOLD signal intensity in other regions that contribute to pain processing, such as the parabrachial nucleus and superior colliculus. Mechanical stimulation in capsaicin-treated rats, but not placebo-treated rats, induced a significant decrease in BOLD signal intensity in the PAG (p<0.001). These data demonstrate that the noxious substance capsaicin produces brain activation in the midbrain regions and reveals the importance of the PAG in central sensitization. PMID:16843597

  5. Experience-dependent plasticity in the inferior colliculus: a site for visual calibration of the neural representation of auditory space in the barn owl.

    PubMed

    Brainard, M S; Knudsen, E I

    1993-11-01

    The optic tectum (homolog of the superior colliculus) contains mutually aligned neural maps of auditory and visual space. During development, the organization of the auditory map is guided by spatial information provided by vision: barn owls raised wearing prismatic spectacles, which optically shift the visual field and the visual map in the optic tectum, develop an auditory map that is shifted by an approximately equivalent amount, such that alignment between the two maps is preserved (Knudsen and Brainard, 1991). In this study we investigated whether this shift in the auditory map is intrinsic to the optic tectum or whether it reflects plasticity at an earlier stage in the auditory pathway. Owls were raised wearing prismatic spectacles that displaced the visual field by 23 degrees to the left or right. This manipulation alters the normal correspondence between locations in the visual field and interaural time difference (ITD), the primary cue for the azimuth of a sound source. In normal owls and in owls with at least 150 d of prism experience, extracellular unit recordings were used to assess the representations of ITD at anatomically and physiologically defined sites in the optic tectum and in the two prior stages of the auditory pathway, the external and central nuclei of the inferior colliculus (ICx and ICc). In the optic tectum of normal owls, the values of ITD to which units responded most strongly (best ITDs) varied systematically with the azimuths of unit visual receptive fields (VRFs). In the prism-reared owls, best ITDs were shifted from normal toward the values of ITD produced by sounds at the locations of the units' optically displaced VRFs. In the ICx of prism-reared owls, the representation of ITD also was shifted from normal, by an amount and in a direction that could completely account for the shift in ITD measured in the optic tectum. At some sites in the ICx, the shift in ITD tuning was apparent within the first 7-8 msec of the response; shifted

  6. A quantitative comparison of the hemispheric, areal, and laminar origins of sensory and motor cortical projections to the superior colliculus of the cat.

    PubMed

    Butler, Blake E; Chabot, Nicole; Lomber, Stephen G

    2016-09-01

    The superior colliculus (SC) is a midbrain structure central to orienting behaviors. The organization of descending projections from sensory cortices to the SC has garnered much attention; however, rarely have projections from multiple modalities been quantified and contrasted, allowing for meaningful conclusions within a single species. Here, we examine corticotectal projections from visual, auditory, somatosensory, motor, and limbic cortices via retrograde pathway tracers injected throughout the superficial and deep layers of the cat SC. As anticipated, the majority of cortical inputs to the SC originate in the visual cortex. In fact, each field implicated in visual orienting behavior makes a substantial projection. Conversely, only one area of the auditory orienting system, the auditory field of the anterior ectosylvian sulcus (fAES), and no area involved in somatosensory orienting, shows significant corticotectal inputs. Although small relative to visual inputs, the projection from the fAES is of particular interest, as it represents the only bilateral cortical input to the SC. This detailed, quantitative study allows for comparison across modalities in an animal that serves as a useful model for both auditory and visual perception. Moreover, the differences in patterns of corticotectal projections between modalities inform the ways in which orienting systems are modulated by cortical feedback. J. Comp. Neurol. 524:2623-2642, 2016. © 2016 Wiley Periodicals, Inc. PMID:26850989

  7. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

    1989-01-01

    The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  8. Convergence of the nucleus-nucleus Glauber multiple scattering series

    SciTech Connect

    Usmani, A.A.; Ahmad, I. )

    1991-05-01

    The Glauber {ital S}-matrix operator for nucleus-nucleus scattering is expressed as a finite series of matrix elements involving Bell's polynomials. Analyzing {alpha}{sup 4}He elastic-scattering data at the incident momentum of 4.32 GeV/{ital c}, we infer that our expansion is appreciably converging. Further, by applying closure over target and projectile states and neglecting a certain class of terms involving intermediate excitations, we arrive at a recurrence relation for nucleus-nucleus multiple scattering series terms, which invites further study as it seems to provide a simple method for calculating the nucleus-nucleus elastic-scattering cross section.

  9. [Response characteristics of neurons to tone in dorsal nucleus of the lateral lemniscus of the mouse].

    PubMed

    Si, Wen-Juan; Cheng, Yan-Ling; Yang, Dan-Dan; Wang, Xin

    2016-02-25

    The dorsal nucleus of lateral lemniscus (DNLL) is a nucleus in the auditory ascending pathway, and casts inhibitory efferent projections to the inferior colliculus. Studies on the DNLL are less than studies on the auditory brain stem and inferior colliculus. To date, there is no information about response characteristics of neurons in DNLL of albino mouse. Under free field conditions, we used extracellular single unit recording to study the acoustic signal characteristics of DNLL neurons in Kunming mice (Mus musculus). Transient (36%) and ongoing (64%) firing patterns were found in 96 DNLL neurons. Neurons with different firing patterns have significant differences in characteristic frequency and minimal threshold. We recorded frequency tuning curves (FTCs) of 87 DNLL neurons. All of the FTCs exhibit an open "V" shape. There is no significant difference in FTCs between transient and ongoing neurons, but among the ongoing neurons, the FTCs of sustained neurons are sharper than those of onset plus sustained neurons and pauser neurons. Our results showed that the characteristic frequency of DNLL neurons of mice was not correlated with depth, supporting the view that the DNLL of mouse has no frequency topological organization through dorsal-ventral plane, which is different from cats and some other animals. Furthermore, by using rate-intensity function (RIF) analysis the mouse DNLL neurons can be classified as monotonic (60%), saturated (31%) and non-monotonic (8%) types. Each RIF type includes transient and ongoing firing patterns. Dynamic range of the transient firing pattern is smaller than that of ongoing firing ones (P < 0.01), suggesting that the inhibitory inputs may underlie the formation of transient firing pattern. Multiple firing patterns and intensity coding of DNLL neurons may derive from the projections from multiple auditory nuclei, and play different roles in auditory information processing. PMID:26915316

  10. Orientation-selective Responses in the Mouse Lateral Geniculate Nucleus

    PubMed Central

    Zhao, Xinyu; Chen, Hui; Liu, Xiaorong

    2013-01-01

    The dorsal lateral geniculate nucleus (dLGN) receives visual information from the retina and transmits it to the cortex. In this study, we made extracellular recordings in the dLGN of both anesthetized and awake mice, and found that a surprisingly high proportion of cells were selective for stimulus orientation. The orientation selectivity of dLGN cells was unchanged after silencing the visual cortex pharmacologically, indicating that it is not due to cortical feedback. The orientation tuning of some dLGN cells correlated with their elongated receptive fields, while in others orientation selectivity was observed despite the fact that their receptive fields were circular, suggesting that their retinal input might already be orientation selective. Consistently, we revealed orientation/axis-selective ganglion cells in the mouse retina using multielectrode arrays in an in vitro preparation. Furthermore, the orientation tuning of dLGN cells was largely maintained at different stimulus contrasts, which could be sufficiently explained by a simple linear feedforward model. We also compared the degree of orientation selectivity in different visual structures under the same recording condition. Compared with the dLGN, orientation selectivity is greatly improved in the visual cortex, but is similar in the superior colliculus, another major retinal target. Together, our results demonstrate prominent orientation selectivity in the mouse dLGN, which may potentially contribute to visual processing in the cortex. PMID:23904611

  11. Nucleus Course in Japanese.

    ERIC Educational Resources Information Center

    Akiyama, Nobuo; Flamm, Carol S.

    The "Nucleus Course in Japanese," based on the Institute of Modern Languages'"Situational Reinforcement" approach, is designed for 80 to 100 hours of instruction. Each lesson has several sections--Response drills, Appropriate Response Sequence, and Reading. Most of the lessons also include optional sections with Sentences for Repetition or a…

  12. Cell nucleus in context

    SciTech Connect

    Lelievre, Sophie A.; Bissell, Mina J.; Pujuguet, Philippe

    1999-11-11

    The molecular pathways that participate in regulation of gene expression are being progressively unraveled. Extracellular signals, including the binding of extracellular matrix and soluble molecules to cell membrane receptors, activate specific signal transducers that convey information inside the cell and can alter gene products. Some of these transducers when translocated to the cell nucleus may bind to transcription complexes and thereby modify the transcriptional activity of specific genes. However, the basic molecules involved in the regulation of gene expression are found in many different cell and tissue types; thus the mechanisms underlying tissue-specific gene expression are still obscure. In this review, we focus on the study of signals that are conveyed to the nucleus. We propose that the way in which extracellular signals are integrated may account for tissue-specific gene expression. We argue that the integration of signals depends on the structural organization of cells ( i.e., extracellular matrix, cell membrane, cytoskeleton, nucleus) which a particular cell type within a tissue. Putting the nuclei in context allows us to envision gene expression as being regulated not only by the communication between the extracellular environment and the nucleus, but also by the influence of organized assemblies of cells on extracellular-nuclear communications.

  13. Auditory cortical axons contact commissural cells throughout the guinea pig inferior colliculus.

    PubMed

    Nakamoto, Kyle T; Sowick, Colleen S; Schofield, Brett R

    2013-12-01

    Projections from auditory cortex (AC) affect how cells in both inferior colliculi (IC) respond to acoustic stimuli. The large projection from the AC to the ipsilateral IC is usually credited with the effects in the ipsilateral IC. The circuitry underlying effects in the contralateral IC is less clear. The direct projection from the AC to the contralateral IC is relatively small. An unexplored possibility is that the large ipsilateral cortical projection contacts the substantial number of cells in the ipsilateral IC that project through the commissure to the contralateral IC. Apparent contacts between cortical boutons and commissural cells were identified in the left IC after injection of different fluorescent tracers into the left AC and the right IC. Commissural cells were labeled throughout the left IC, and many (23-34%) appeared to be contacted by cortical axons. In the central nucleus, both disc-shaped and stellate cells were contacted. Antibodies to glutamic acid decarboxylase (GAD) were used to identify GABAergic commissural cells. The majority (>86%) of labeled commissural cells were GAD-immunonegative. Despite low numbers of GAD-immunopositive commissural cells, some of these cells were contacted by cortical boutons. Nonetheless, most cortically contacted commissural cells were GAD-immunonegative (i.e., presumably glutamatergic). We conclude that auditory cortical axons contact primarily excitatory commissural cells in the ipsilateral IC that project to the contralateral IC. These corticocollicular contacts occur in each subdivision of the ipsilateral IC, suggesting involvement of commissural cells throughout the IC. This pathway - from AC to commissural cells in the ipsilateral IC - is a prime candidate for the excitatory effects of activation of the auditory cortex on responses in the contralateral IC. Overall this suggests that the auditory corticofugal pathway is integrated with midbrain commissural connections. PMID:24140579

  14. Complex somatosensory receptive fields of cells in the deep laminae of the hamster's superior colliculus.

    PubMed

    Rhoades, R W; Mooney, R D; Jacquin, M F

    1983-07-01

    Responses to separate and simultaneous application of noxious and innocuous tactile stimuli were examined for neurons recorded from the deep layers of the hamster's superior colliculus. Forty-four percent of the units isolated were responsive only to innocuous, primarily cutaneous, stimuli; 10% were activated only by noxious stimulation; and 15% were characterized as having a wide dynamic range. The remaining 31% of the somatosensory cells recorded had complex receptive field properties which have not heretofore been described for tectal neurons in any species. Ten percent of all somatosensory cells had no excitatory receptive fields, but their spontaneous discharges could be suppressed by low threshold and/or noxious stimulation of discrete portions of the body. In 18% of the units which we recorded, innocuous and noxious stimuli had opposing effects upon cellular activity. Most of these neurons had small receptive fields in which innocuous tactile stimuli yielded excitation and larger fields, often including most of the body surface, where noxious stimulation suppressed both spontaneous activity and the responses normally elicited by appropriate tactile stimulation. Finally, a very small number of units (3% of all somatosensory cells recorded) had multiple receptive fields in which low threshold stimulation produced opposing effects on spontaneous activity. Somatosensory units were recorded in all of the deep laminae, but cells with complex response characteristics were isolated primarily in stratum griseum profundum. PMID:6864251

  15. Altered map of visual space in the superior colliculus of mice lacking early retinal waves.

    PubMed

    Mrsic-Flogel, Thomas D; Hofer, Sonja B; Creutzfeldt, Claire; Cloëz-Tayarani, Isabelle; Changeux, Jean-Pierre; Bonhoeffer, Tobias; Hübener, Mark

    2005-07-20

    During the development of the mammalian retinocollicular projection, a coarse retinotopic map is set up by the graded distribution of axon guidance molecules. Subsequent refinement of the initially diffuse projection has been shown to depend on the spatially correlated firing of retinal ganglion cells. In this scheme, the abolition of patterned retinal activity is not expected to influence overall retinotopic organization, but this has not been investigated. We used optical imaging of intrinsic signals to visualize the complete retinotopic map in the superior colliculus (SC) of mice lacking early retinal waves, caused by the deletion of the beta2 subunit of the nicotinic acetylcholine receptor. As expected from previous anatomical studies in the SC of beta2(-/-) mice, regions activated by individual visual stimuli were much larger and had less sharp borders than those in wild-type mice. Importantly, however, we also found systematic distortions of the entire retinotopic map: the map of visual space was expanded anteriorly and compressed posteriorly. Thus, patterned neuronal activity in the early retina has a substantial influence on the coarse retinotopic organization of the SC. PMID:16033902

  16. Nitric oxide synthase expression in the opossum superior colliculus: a histochemical, immunohistochemical and biochemical study.

    PubMed

    Giraldi-Guimarães, A; Tenório, F; Brüning, G; Mayer, B; Mendez-Otero, R; Cavalcante, L A

    1999-12-01

    The expression of neuronal nitric oxide synthase (nNOS) in the superior colliculus (SC) of the opossum Didelphis marsupialis was studied by NADPH diaphorase (NADPH-d) histochemistry and nNOS immunohistochemistry. In addition, the activity of nNOS was quantified by measurement of [(3)H]-L-arginine conversion to [(3)H]-L-citrulline in tissue extracts from SC superficial layers in opossums and rats. Our results show that the number of NADPH-d stained cells was small and virtually identical in stratum opticum (SO) and stratum griseum superficiale (SGS) and their staining was very light, particularly in SGS. Neuropil staining was heavier in the stratum zonale (SZ) than in SGS or SO. The intermediate and deep layers contained heavily stained cells and moderate neuropil staining. Surprisingly, nNOS-immunoreactive cells were far more numerous than NADPH-d+ cells in every layer. The production of [(3)H]-L-citrulline from [(3)H]-L-arginine in tissue extracts enriched in superficial layers indicated that nNOS specific activity is as high in the opossum as in the rat. Our results suggest that the location of nNOS-expressing neurons in retino-receptive layers may be related to inter-specific differences in the processing of visual information. PMID:10681601

  17. Synaptogenesis in retino-receptive layers of the superior colliculus of the opossum Didelphis marsupialis.

    PubMed

    Correa-Gillieron, E M; Cavalcante, L A

    1999-08-01

    The maturation of the neuropil and synapse formation were examined in the retino-receptive layers of the superior colliculus (SCr-r) in the opossum from a period prior to the onset of arborization of retinocollicular fibers (postnatal day 22 - P22), at 44% of the coecal period (CP), to the end of the fast phase of optic fiber myelination and weaning time (P81 - 118% CP). Development of the SCr-r neuropil follows a protracted time course and can be divided into three broad stages, which are characterized by (I) Large extracellular spaces, numerous growth cones that participate rarely in synaptic junctions, vesicles-poor immature synapses (P22-P30), (II) Synapses of varied morphology with abundant synaptic vesicles, and small terminals with dark mitochondria and round synaptic vesicles (RSD terminals) synapsing mostly onto dendritic shafts, flat-vesicles (F) terminals (P40-P56), (III) Sequential appearance of retinal (R) and pleomorphic-vesicles (P) terminals and of RSD terminals synapsing onto spine or spine-like processes, appearance of glomerulus-like synaptic arrays (synaptic islets) (P61-P81). The advancement of synaptogenesis in SCr-r from stage I to II and from stage II to III correlates closely with the differentiation of astrocytes and oligodendrocytes, respectively. PMID:10529520

  18. The serotonin releaser fenfluramine alters the auditory responses of inferior colliculus neurons.

    PubMed

    Hall, Ian C; Hurley, Laura M

    2007-06-01

    Local direct application of the neuromodulator serotonin strongly influences auditory response properties of neurons in the inferior colliculus (IC), but endogenous stores of serotonin may be released in a distinct spatial or temporal pattern. To explore this issue, the serotonin releaser fenfluramine was iontophoretically applied to extracellularly recorded neurons in the IC of the Mexican free-tailed bat (Tadarida brasiliensis). Fenfluramine mimicked the effects of serotonin on spike count and first spike latency in most neurons, and its effects could be blocked by co-application of serotonin receptor antagonists, consistent with fenfluramine-evoked serotonin release. Responses to fenfluramine did not vary during single applications or across multiple applications, suggesting that fenfluramine did not deplete serotonin stores. A predicted gradient in the effects of fenfluramine with serotonin fiber density was not observed, but neurons with fenfluramine-evoked increases in latency occurred at relatively greater recording depths compared to other neurons with similar characteristic frequencies. These findings support the conclusion that there may be spatial differences in the effects of exogenous and endogenous sources of serotonin, but that other factors such as the identities and locations of serotonin receptors are also likely to play a role in determining the dynamics of serotonergic effects. PMID:17339086

  19. Direct projections from the dorsal premotor cortex to the superior colliculus in the macaque (macaca mulatta).

    PubMed

    Distler, Claudia; Hoffmann, Klaus-Peter

    2015-11-01

    The dorsal premotor cortex (PMd) is part of the cortical network for arm movements during reach-related behavior. Here we investigate the neuronal projections from the PMd to the midbrain superior colliculus (SC), which also contains reach-related neurons, to investigate how the SC integrates into a cortico-subcortical network responsible for initiation and modulation of goal-directed arm movements. By using anterograde transport of neuronal tracers, we found that the PMd projects most strongly to the deep layers of the lateral part of the SC and the underlying reticular formation corresponding to locations where reach-related neurons have been recorded, and from where descending tectofugal projections arise. A somewhat weaker projection targets the intermediate layers of the SC. By contrast, terminals originating from prearcuate area 8 mainly project to the intermediate layers of the SC. Thus, this projection pattern strengthens the view that different compartments in the SC are involved in the control of gaze and in the control or modulation of reaching movements. The PMD-SC projection assists in the participation of the SC in the skeletomotor system and provides the PMd with a parallel path to elicit forelimb movements. PMID:25921755

  20. Superior Colliculus Responses to Attended, Unattended, and Remembered Saccade Targets during Smooth Pursuit Eye Movements.

    PubMed

    Dash, Suryadeep; Nazari, Sina Alipour; Yan, Xiaogang; Wang, Hongying; Crawford, J Douglas

    2016-01-01

    In realistic environments, keeping track of multiple visual targets during eye movements likely involves an interaction between vision, top-down spatial attention, memory, and self-motion information. Recently we found that the superior colliculus (SC) visual memory response is attention-sensitive and continuously updated relative to gaze direction. In that study, animals were trained to remember the location of a saccade target across an intervening smooth pursuit (SP) eye movement (Dash et al., 2015). Here, we modified this paradigm to directly compare the properties of visual and memory updating responses to attended and unattended targets. Our analysis shows that during SP, active SC visual vs. memory updating responses share similar gaze-centered spatio-temporal profiles (suggesting a common mechanism), but updating was weaker by ~25%, delayed by ~55 ms, and far more dependent on attention. Further, during SP the sum of passive visual responses (to distracter stimuli) and memory updating responses (to saccade targets) closely resembled the responses for active attentional tracking of visible saccade targets. These results suggest that SP updating signals provide a damped, delayed estimate of attended location that contributes to the gaze-centered tracking of both remembered and visible saccade targets. PMID:27147987

  1. Brain derived neurotrophic factor keeps pattern electroretinogram from dropping after superior colliculus lesion in mice

    PubMed Central

    Yang, Bin-Bin; Yang, Xu; Ding, Huai-Yu

    2016-01-01

    AIM To determine if brain-derived neurotrophic factor (BDNF) could offer protention to retinal ganglion cells following a superior colliculus (SC) lesion in mice using pattern electroretinogram (PERG) and optical coherence tomography (OCT) as a measures of ganglion cell response and retinal health. METHODS Seven C57BL/6J mice with BDNF protection were tested with PERG and OCT before and after SC lesions. RESULTS Compared with baseline PERG, the amplitude of PERG decreased 11.7% after SC lesions, but not significantly (P>0.05). Through fast Fourier transform (FFT) analysis of the PERGs before and after SC lesions, it was found that dominant frequency of PERGs stayed unchanged, suggesting that the ganglion cells of the retina remained relatively healthy inspite of damage to the ends of the ganglion cell axons. Also, OCT showed no changes in retinal thickness after lesions. CONCLUSION It was concluded that BDNF is essential component of normal retinal and helps retina keeping normal function. While retina lack of BDNF, ex vivo resource of BDNF provides protection to the sick retina. It implies that BDNF is a kind therapeutic neurotrophic factor to retina neurodegeneration diseases, such as glaucoma, age related macular degeneration. PMID:27158604

  2. Superior Colliculus Responses to Attended, Unattended, and Remembered Saccade Targets during Smooth Pursuit Eye Movements

    PubMed Central

    Dash, Suryadeep; Nazari, Sina Alipour; Yan, Xiaogang; Wang, Hongying; Crawford, J. Douglas

    2016-01-01

    In realistic environments, keeping track of multiple visual targets during eye movements likely involves an interaction between vision, top-down spatial attention, memory, and self-motion information. Recently we found that the superior colliculus (SC) visual memory response is attention-sensitive and continuously updated relative to gaze direction. In that study, animals were trained to remember the location of a saccade target across an intervening smooth pursuit (SP) eye movement (Dash et al., 2015). Here, we modified this paradigm to directly compare the properties of visual and memory updating responses to attended and unattended targets. Our analysis shows that during SP, active SC visual vs. memory updating responses share similar gaze-centered spatio-temporal profiles (suggesting a common mechanism), but updating was weaker by ~25%, delayed by ~55 ms, and far more dependent on attention. Further, during SP the sum of passive visual responses (to distracter stimuli) and memory updating responses (to saccade targets) closely resembled the responses for active attentional tracking of visible saccade targets. These results suggest that SP updating signals provide a damped, delayed estimate of attended location that contributes to the gaze-centered tracking of both remembered and visible saccade targets. PMID:27147987

  3. Decreased norepinephrine (NE) uptake in cerebral cortex and inferior colliculus of genetically epilepsy prone (GEP) rats

    SciTech Connect

    Browning, R.A.; Rigler-Daugherty, S.K.; Long, G.; Jobe, P.C.; Wade, D.R.

    1986-03-01

    GEP rats are characterized by an enhanced susceptibility to seizures caused by a variety of stimuli, most notably sound. Pharmacological treatments that reduce the synaptic concentration of NE increase seizure severity in GEP rats while elevations in NE have the opposite effect. GEP rats also display a widespread deficit in brain NE concentration suggesting that their increased seizure susceptibility is related to a deficit in noradrenergic transmission. The authors have compared the kinetics of /sup 3/H-NE uptake in the P/sub 2/ synaptosomal fraction isolated from the cerebral cortex of normal and GEP-rats. Although the apparent Kms were not significantly different (Normal +/- SEM:0.37 +/- 0.13..mu..M; GEP +/- SEM: 0.29 +/- 0.07..mu..M), the Vmax for GEP rats was 48% lower than that of normal rats (Normal +/- SEM: 474 +/- 45 fmole/mg/4min; GEP +/- SEM: 248 +/- 16 fmole/mg/4min). Because of the possible role of the inferior colliculus (IC) in the initiation of sound-induced seizures in GEP rats, the authors measured synaptosomal NE uptake in the IC using a NE concentration of 50 nM. The IC synaptosomal NE uptake was found to be 35% lower in GEP than in normal rats. These findings are consistent with the hypothesis that a deficit in noradrenergic transmission is related to the increased seizure susceptibility of GEP rats.

  4. Adaptive visual and auditory map alignment in barn owl superior colliculus and its neuromorphic implementation.

    PubMed

    Huo, Juan; Murray, Alan; Wei, Dongqing

    2012-09-01

    Adaptation is one of the most important phenomena in biology. A young barn owl can adapt to imposed environmental changes, such as artificial visual distortion caused by wearing a prism. This adjustment process has been modeled mathematically and the model replicates the sensory map realignment of barn owl superior colliculus (SC) through axonogenesis and synaptogenesis. This allows the biological mechanism to be transferred to an artificial computing system and thereby imbue it with a new form of adaptability to the environment. The model is demonstrated in a real-time robot environment. Results of the experiments are compared with and without prism distortion of vision, and show improved adaptability for the robot. However, the computation speed of the embedded system in the robot is slow. A digital and analog mixed signal very-large-scale integration (VLSI) circuit has been fabricated to implement adaptive sensory pathway changes derived from the SC model at higher speed. VLSI experimental results are consistent with simulation results. PMID:24807931

  5. Alignment of multimodal sensory input in the superior colliculus through a gradient-matching mechanism

    PubMed Central

    Phan, An; Yamada, Jena; Feldheim, David A.

    2012-01-01

    The superior colliculus (SC) is a midbrain structure that integrates visual, somatosensory and auditory inputs to direct head and eye movements. Each of these modalities is topographically mapped and aligned with the others to ensure precise behavioral responses to multimodal stimuli. While it is clear that neural activity is instructive for topographic alignment of inputs from the visual cortex (V1) and auditory system with retinal axons in the SC, there is also evidence that activity-independent mechanisms are used to establish topographic alignment between modalities. Here, we show that the topography of the projection from primary somatosensory cortex (S1) to the SC is established during the first postnatal week. Unlike V1-SC projections, the S1-SC projection does not bifurcate when confronted with a duplicated retinocollicular map, showing that retinal input in the SC does not influence the topography of the S1-SC projection. However, S1-SC topography is disrupted in mice lacking ephrins-As, which we find are expressed in graded patterns along with their binding partners, the EphA4 and EphA7, in both S1 and the somatosensory recipient layer of the SC. Taken together, these data support a model in which somatosensory inputs into the SC map topographically and establish alignment with visual inputs in the SC using a gradient-matching mechanism. PMID:22496572

  6. Excitatory Synaptic Feedback from the Motor Layer to the Sensory Layers of the Superior Colliculus

    PubMed Central

    Ghitani, Nima; Bayguinov, Peter O.; Vokoun, Corinne R.; McMahon, Shane

    2014-01-01

    Neural circuits that translate sensory information into motor commands are organized in a feedforward manner converting sensory information into motor output. The superior colliculus (SC) follows this pattern as it plays a role in converting visual information from the retina and visual cortex into motor commands for rapid eye movements (saccades). Feedback from movement to sensory regions is hypothesized to play critical roles in attention, visual image stability, and saccadic suppression, but in contrast to feedforward pathways, motor feedback to sensory regions has received much less attention. The present study used voltage imaging and patch-clamp recording in slices of rat SC to test the hypothesis of an excitatory synaptic pathway from the motor layers of the SC back to the sensory superficial layers. Voltage imaging revealed an extensive depolarization of the superficial layers evoked by electrical stimulation of the motor layers. A pharmacologically isolated excitatory synaptic potential in the superficial layers depended on stimulus strength in the motor layers in a manner consistent with orthodromic excitation. Patch-clamp recording from neurons in the sensory layers revealed excitatory synaptic potentials in response to glutamate application in the motor layers. The location, size, and morphology of responsive neurons indicated they were likely to be narrow-field vertical cells. This excitatory projection from motor to sensory layers adds an important element to the circuitry of the SC and reveals a novel feedback pathway that could play a role in enhancing sensory responses to attended targets as well as visual image stabilization. PMID:24828636

  7. HEBBIAN MECHANISMS HELP EXPLAIN DEVELOPMENT OF MULTISENSORY INTEGRATION IN THE SUPERIOR COLLICULUS: A NEURAL NETWORK MODEL

    PubMed Central

    Cuppini, C.; Magosso, E.; Rowland, B.; Stein, B.; Ursino, M.

    2013-01-01

    The superior colliculus (SC) integrates relevant sensory information (visual, auditory, somatosensory) from several cortical and subcortical structures, to program orientation responses to external events. However, this capacity is not present at birth, and it is acquired only through interactions with cross-modal events during maturation. Mathematical models provide a quantitative framework, valuable in helping to clarify the specific neural mechanisms underlying the maturation of the multisensory integration in the SC. We extended a neural network model of the adult SC (Cuppini et al. 2010) to describe the development of this phenomenon starting from an immature state, based on known or suspected anatomy and physiology, in which: 1) AES afferents are present but weak, 2) Responses are driven from non-AES afferents, and 3) The visual inputs have a marginal spatial tuning. Sensory experience was modelled by repeatedly presenting modality-specific and cross-modal stimuli. Synapses in the network were modified by simple Hebbian learning rules. As a consequence of this exposure, 1) Receptive fields shrink and come into spatial register, and 2) SC neurons gained the adult characteristic integrative properties: enhancement, depression, and inverse effectiveness. Importantly, the unique architecture of the model guided the development so that integration became dependent on the relationship between the cortical input and the SC. Manipulations of the statistics of the experience during the development changed the integrative profiles of the neurons, and results matched well with the results of physiological studies. PMID:23011260

  8. GATA2 IS REQUIRED FOR MIGRATION AND DIFFERENTIATION OF RETINORECIPIENT NEURONS IN THE SUPERIOR COLLICULUS

    PubMed Central

    Willett, Ryan T.; Greene, Lloyd A.

    2011-01-01

    The superior colliculus (SC)/optic tectum of the dorsal mesencephalon plays a major role in responses to visual input, yet regulation of neuronal differentiation within this layered structure is only partially understood. Here, we show that the zinc finger transcription factor Gata2 is required for normal SC development. Starting at e15 (corresponding to the times at which neurons of the outer and intermediate layers of the SC are generated), Gata2 is transiently expressed in the rat embryonic dorsal mesencephalon within a restricted region between proliferating cells of the ventricular zone and the deepest neuronal layers of the developing SC. The Gata2 positive cells are post-mitotic and lack markers of differentiated neurons, but express markers for immature neuronal precursors including Ascl1 and Pax3/7. In utero electroporation with Gata2 shRNAs at e16 into cells along the dorsal mesencephalic ventricle interferes with their normal migration into the SC and maintains them in a state characterized by retention of Pax3 expression and the absence of mature neuronal markers. Collectively, these findings indicate that Gata2 plays a required role in the transition of post-mitotic neuronal precursor cells of the retinorecipient layers of the SC into mature neurons and that loss of Gata2 arrests them at an intermediate stage of differentiation. PMID:21430145

  9. Periodotopy in the gerbil inferior colliculus: local clustering rather than a gradient map

    PubMed Central

    Schnupp, Jan W. H.; Garcia-Lazaro, Jose A.; Lesica, Nicholas A.

    2015-01-01

    Periodicities in sound waveforms are widespread, and shape important perceptual attributes of sound including rhythm and pitch. Previous studies have indicated that, in the inferior colliculus (IC), a key processing stage in the auditory midbrain, neurons tuned to different periodicities might be arranged along a periodotopic axis which runs approximately orthogonal to the tonotopic axis. Here we map out the topography of frequency and periodicity tuning in the IC of gerbils in unprecedented detail, using pure tones and different periodic sounds, including click trains, sinusoidally amplitude modulated (SAM) noise and iterated rippled noise. We found that while the tonotopic map exhibited a clear and highly reproducible gradient across all animals, periodotopic maps varied greatly across different types of periodic sound and from animal to animal. Furthermore, periodotopic gradients typically explained only about 10% of the variance in modulation tuning between recording sites. However, there was a strong local clustering of periodicity tuning at a spatial scale of ca. 0.5 mm, which also differed from animal to animal. PMID:26379508

  10. Stimulus-specific adaptation in the inferior colliculus of the mouse: anesthesia and spontaneous activity effects.

    PubMed

    Duque, Daniel; Malmierca, Manuel S

    2015-11-01

    Rapid behavioral responses to unexpected events in the acoustic environment are critical for survival. Stimulus-specific adaptation (SSA) is the process whereby some auditory neurons respond better to rare stimuli than to repetitive stimuli. Most experiments on SSA have been performed under anesthesia, and it is unknown if SSA sensitivity is altered by the anesthetic agent. Only a direct comparison can answer this question. Here, we recorded extracellular single units in the inferior colliculus of awake and anesthetized mice under an oddball paradigm that elicits SSA. Our results demonstrate that SSA is similar, but not identical, in the awake and anesthetized preparations. The differences are mostly due to the higher spontaneous activity observed in the awake animals, which also revealed a high incidence of inhibitory receptive fields. We conclude that SSA is not an artifact of anesthesia and that spontaneous activity modulates neuronal SSA differentially, depending on the state of arousal. Our results suggest that SSA may be especially important when nervous system activity is suppressed during sleep-like states. This may be a useful survival mechanism that allows the organism to respond to danger when sleeping. PMID:25115620

  11. Distribution of GABAergic cells in the inferior colliculus that project to the thalamus

    PubMed Central

    Mellott, Jeffrey G.; Foster, Nichole L.; Nakamoto, Kyle T.; Motts, Susan D.; Schofield, Brett R.

    2014-01-01

    A GABAergic component has been identified in the projection from the inferior colliculus (IC) to the medial geniculate body (MG) in cats and rats. We sought to determine if this GABAergic pathway exists in guinea pig, a species widely used in auditory research. The guinea pig IC contains GABAergic cells, but their relative abundance in the IC and their relative contributions to tectothalamic projections are unknown. We identified GABAergic cells with immunochemistry for glutamic acid decarboxylase (GAD) and determined that ~21% of IC neurons are GABAergic. We then combined retrograde tracing with GAD immunohistochemistry to identify the GABAergic tectothalamic projection. Large injections of Fast Blue, red fluorescent beads or FluoroGold were deposited to include all subdivisions of the MG. The results demonstrate a GABAergic pathway from each IC subdivision to the ipsilateral MG. GABAergic cells constitute ~22% of this ipsilateral pathway. In addition, each subdivision of the IC had a GABAergic projection to the contralateral MG. Measured by number of tectothalamic cells, the contralateral projection is about 10% of the size of the ipsilateral projection. GABAergic cells constitute about 20% of the contralateral projection. In summary, the results demonstrate a tectothalamic projection in guinea pigs that originates in part from GABAergic cells that project ipsilaterally or contralaterally to the MG. The results show similarities to both rats and cats, and carry implications for the role of GABAergic tectothalamic projections vis-à-vis the presence (in cats) or near absence (in rats and guinea pigs) of GABAergic interneurons in the MG. PMID:24744703

  12. Periodotopy in the gerbil inferior colliculus: local clustering rather than a gradient map.

    PubMed

    Schnupp, Jan W H; Garcia-Lazaro, Jose A; Lesica, Nicholas A

    2015-01-01

    Periodicities in sound waveforms are widespread, and shape important perceptual attributes of sound including rhythm and pitch. Previous studies have indicated that, in the inferior colliculus (IC), a key processing stage in the auditory midbrain, neurons tuned to different periodicities might be arranged along a periodotopic axis which runs approximately orthogonal to the tonotopic axis. Here we map out the topography of frequency and periodicity tuning in the IC of gerbils in unprecedented detail, using pure tones and different periodic sounds, including click trains, sinusoidally amplitude modulated (SAM) noise and iterated rippled noise. We found that while the tonotopic map exhibited a clear and highly reproducible gradient across all animals, periodotopic maps varied greatly across different types of periodic sound and from animal to animal. Furthermore, periodotopic gradients typically explained only about 10% of the variance in modulation tuning between recording sites. However, there was a strong local clustering of periodicity tuning at a spatial scale of ca. 0.5 mm, which also differed from animal to animal. PMID:26379508

  13. Variability of visual responses of superior colliculus neurons depends on stimulus velocity.

    PubMed

    Mochol, Gabriela; Wójcik, Daniel K; Wypych, Marek; Wróbel, Andrzej; Waleszczyk, Wioletta J

    2010-03-01

    Visually responding neurons in the superficial, retinorecipient layers of the cat superior colliculus receive input from two primarily parallel information processing channels, Y and W, which is reflected in their velocity response profiles. We quantified the time-dependent variability of responses of these neurons to stimuli moving with different velocities by Fano factor (FF) calculated in discrete time windows. The FF for cells responding to low-velocity stimuli, thus receiving W inputs, increased with the increase in the firing rate. In contrast, the dynamics of activity of the cells responding to fast moving stimuli, processed by Y pathway, correlated negatively with FF whether the response was excitatory or suppressive. These observations were tested against several types of surrogate data. Whereas Poisson description failed to reproduce the variability of all collicular responses, the inclusion of secondary structure to the generating point process recovered most of the observed features of responses to fast moving stimuli. Neither model could reproduce the variability of low-velocity responses, which suggests that, in this case, more complex time dependencies need to be taken into account. Our results indicate that Y and W channels may differ in reliability of responses to visual stimulation. Apart from previously reported morphological and physiological differences of the cells belonging to Y and W channels, this is a new feature distinguishing these two pathways. PMID:20203179

  14. Hebbian mechanisms help explain development of multisensory integration in the superior colliculus: a neural network model.

    PubMed

    Cuppini, C; Magosso, E; Rowland, B; Stein, B; Ursino, M

    2012-12-01

    The superior colliculus (SC) integrates relevant sensory information (visual, auditory, somatosensory) from several cortical and subcortical structures, to program orientation responses to external events. However, this capacity is not present at birth, and it is acquired only through interactions with cross-modal events during maturation. Mathematical models provide a quantitative framework, valuable in helping to clarify the specific neural mechanisms underlying the maturation of the multisensory integration in the SC. We extended a neural network model of the adult SC (Cuppini et al., Front Integr Neurosci 4:1-15, 2010) to describe the development of this phenomenon starting from an immature state, based on known or suspected anatomy and physiology, in which: (1) AES afferents are present but weak, (2) Responses are driven from non-AES afferents, and (3) The visual inputs have a marginal spatial tuning. Sensory experience was modeled by repeatedly presenting modality-specific and cross-modal stimuli. Synapses in the network were modified by simple Hebbian learning rules. As a consequence of this exposure, (1) Receptive fields shrink and come into spatial register, and (2) SC neurons gained the adult characteristic integrative properties: enhancement, depression, and inverse effectiveness. Importantly, the unique architecture of the model guided the development so that integration became dependent on the relationship between the cortical input and the SC. Manipulations of the statistics of the experience during the development changed the integrative profiles of the neurons, and results matched well with the results of physiological studies. PMID:23011260

  15. Separate visual signals for saccade initiation during target selection in the primate superior colliculus.

    PubMed

    White, Brian J; Munoz, Douglas P

    2011-02-01

    The primary function of the superior colliculus (SC) is to orient the visual system toward behaviorally relevant stimuli defined by features such as color. However, a longstanding view has held that visual activity in the SC arises exclusively from achromatic pathways. Recently, we reported evidence that the primate SC is highly sensitive to signals originating from chromatic pathways, but these signals are delayed relative to luminance signals (White et al., 2009). Here, we describe a functional consequence of this difference in visual arrival time on the processes leading to target selection and saccade initiation. Two rhesus monkeys performed a simple color-singleton selection task in which stimuli carried a chromatic component only (target and distractors were isoluminant with the background, but differed in chromaticity) or a combined chromatic-achromatic component (36% luminance contrast added equally to all stimuli). Although visual responses were delayed in the chromatic-only relative to the combined chromatic-achromatic condition, SC neurons discriminated the target from distractors at approximately the same time provided stimulus chromaticity was held constant. However, saccades were triggered sooner, and with more errors, with the chromatic-achromatic condition, suggesting that luminance signals associated with these stimuli increased the probability of triggering a saccade before the target color was adequately discriminated. These results suggest that separate mechanisms may independently influence the saccadic command in the SC, one linked to the arrival time of pertinent visual signals, and another linked to the output of the visual selection process. PMID:21289164

  16. A sodium afterdepolarization in rat superior colliculus neurons and its contribution to population activity.

    PubMed

    Ghitani, Nima; Bayguinov, Peter O; Basso, Michele A; Jackson, Meyer B

    2016-07-01

    The mammalian superior colliculus (SC) is a midbrain structure that integrates multimodal sensory inputs and computes commands to initiate rapid eye movements. SC neurons burst with the sudden onset of a visual stimulus, followed by persistent activity that may underlie shifts of attention and decision making. Experiments in vitro suggest that circuit reverberations play a role in the burst activity in the SC, but the origin of persistent activity is unclear. In the present study we characterized an afterdepolarization (ADP) that follows action potentials in slices of rat SC. Population responses seen with voltage-sensitive dye imaging consisted of rapid spikes followed immediately by a second distinct depolarization of lower amplitude and longer duration. Patch-clamp recordings showed qualitatively similar behavior: in nearly all neurons throughout the SC, rapid spikes were followed by an ADP. Ionic and pharmacological manipulations along with experiments with current and voltage steps indicated that the ADP of SC neurons arises from Na(+) current that either persists or resurges following Na(+) channel inactivation at the end of an action potential. Comparisons of pharmacological properties and frequency dependence revealed a clear parallel between patch-clamp recordings and voltage imaging experiments, indicating a common underlying membrane mechanism for the ADP in both single neurons and populations. The ADP can initiate repetitive spiking at intervals consistent with the frequency of persistent activity in the SC. These results indicate that SC neurons have intrinsic membrane properties that can contribute to electrical activity that underlies shifts of attention and decision making. PMID:27075543

  17. Inhibition shapes selectivity to vocalizations in the inferior colliculus of awake mice

    PubMed Central

    Mayko, Zachary M.; Roberts, Patrick D.; Portfors, Christine V.

    2012-01-01

    The inferior colliculus (IC) is a major center for integration of auditory information as it receives ascending projections from a variety of brainstem nuclei as well as descending projections from the thalamus and auditory cortex. The ascending projections are both excitatory and inhibitory and their convergence at the IC results in a microcircuitry that is important for shaping responses to simple, binaural, and modulated sounds in the IC. Here, we examined the role inhibition plays in shaping selectivity to vocalizations in the IC of awake, normal-hearing adult mice (CBA/CaJ strain). Neurons in the IC of mice show selectivity in their responses to vocalizations, and we hypothesized that this selectivity is created by inhibitory microcircuitry in the IC. We compared single unit responses in the IC to pure tones and a variety of ultrasonic mouse vocalizations before and after iontophoretic application of GABAA receptor (GABAAR) and glycine receptor (GlyR) antagonists. The most pronounced effects of blocking GABAAR and GlyR on IC neurons were to increase spike rates and broaden excitatory frequency tuning curves in response to pure tone stimuli, and to decrease selectivity to vocalizations. Thus, inhibition plays an important role in creating selectivity to vocalizations in the IC. PMID:23087616

  18. A hard-wired priority map in the superior colliculus shaped by asymmetric inhibitory circuitry

    PubMed Central

    Bayguinov, Peter O.; Ghitani, Nima; Jackson, Meyer B.

    2015-01-01

    The mammalian superior colliculus (SC) is a laminar midbrain structure that translates visual signals into commands to shift the focus of attention and gaze. The SC plays an integral role in selecting targets and ultimately generating rapid eye movements to those targets. In all mammals studied to date, neurons in the SC are arranged topographically such that the location of visual stimuli and the endpoints of orienting movements form organized maps in superficial and deeper layers, respectively. The organization of these maps is thought to underlie attentional priority by assessing which regions of the visual field contain behaviorally relevant information. Using voltage imaging and patch-clamp recordings in parasagittal SC slices from the rat, we found the synaptic circuitry of the visuosensory map in the SC imposes a strong bias. Voltage imaging of responses to electrical stimulation revealed more spread in the caudal direction than the rostral direction. Pharmacological experiments demonstrated that this asymmetry arises from GABAA receptor activation rostral to the site of stimulation. Patch-clamp recordings confirmed this rostrally directed inhibitory circuit and showed that it is contained within the visuosensory layers of the SC. Stimulation of two sites showed that initial stimulation of a caudal site can take priority over subsequent stimulation of a rostral site. Taken together, our data indicate that the circuitry of the visuosensory SC is hard-wired to give higher priority to more peripheral targets, and this property is conferred by a uniquely structured, dedicated inhibitory circuit. PMID:25995346

  19. Synaptic response patterns of neurons in the cortex of rat inferior colliculus.

    PubMed

    Li, Y; Evans, M S; Faingold, C L

    1999-11-01

    The present study examined synaptic potentials of neurons in inferior colliculus (IC) cortex slice and the roles of GABA and glutamate receptors in generating these potentials. Multipolar (82%) and elongated (18%) cells were observed with intracellular biocytin staining. Electrical stimulation of the IC commissure (CoIC) elicited only inhibitory postsynaptic potentials (IPSPs) (10% of cells), only excitatory postsynaptic potentials (EPSPs) (51%), or both (38%). IPSPs were elicited at lower thresholds and shorter latencies than EPSPs (mean: 1.6+/-1.2 ms) and IPSPs were observed in all neurons following membrane depolarization. Short-latency EPSPs were blocked by non-NMDA receptor antagonists, and longer-latency EPSPs were blocked by NMDA antagonists. CoIC stimulation evoked short-latency IPSPs (mean: 0.55+/-0.33 ms) in 48% of neurons, and the IPSPs persisted despite glutamate receptor blockade, which implies monosynaptic inhibitory input. A GABA(A) antagonist blocked IPSPs and paired pulse inhibition of EPSPs, suggesting GABA(A) receptor mediation. A GABA(B) antagonist reduced paired pulse inhibition of IPSPs, suggesting GABA(B) receptor modulation. Thus, GABA-mediated inhibition plays a critical role in shaping synaptic responses of IC cortex neurons. Normal GABAergic function in IC has been shown to be important in acoustic coding, and reduced efficacy of GABA function in IC neurons is critical in IC pathophysiology in presbycusis, tinnitus and audiogenic seizures. PMID:10545630

  20. Proton Nucleus Elastic Scattering Data.

    Energy Science and Technology Software Center (ESTSC)

    1993-08-18

    Version 00 The Proton Nucleus Elastic Scattering Data file PNESD contains the numerical data and the related bibliography for the differential elastic cross sections, polarization and integral nonelastic cross sections for elastic proton-nucleus scattering.

  1. The retrotrapezoid nucleus and breathing.

    PubMed

    Guyenet, Patrice G; Stornetta, Ruth L; Abbott, Stephen B G; Depuy, Seth D; Kanbar, Roy

    2012-01-01

    The retrotrapezoid nucleus (RTN) is located in the rostral medulla oblongata close to the ventral surface and consists of a bilateral cluster of glutamatergic neurons that are non-aminergic and express homeodomain transcription factor Phox2b throughout life. These neurons respond vigorously to increases in local pCO(2) via cell-autonomous and paracrine (glial) mechanisms and receive additional chemosensory information from the carotid bodies. RTN neurons exclusively innervate the regions of the brainstem that contain the respiratory pattern generator (RPG). Lesion or inhibition of RTN neurons largely attenuates the respiratory chemoreflex of adult rats whereas their activation increases respiratory rate, inspiratory amplitude and active expiration. Phox2b mutations that cause congenital central hypoventilation syndrome in humans prevent the development of RTN neurons in mice. Selective deletion of the RTN Phox2b-VGLUT2 neurons by genetic means in mice eliminates the respiratory chemoreflex in neonates.In short, RTN Phox2b-VGLUT2 neurons are a major nodal point of the CNS network that regulates pCO(2) via breathing and these cells are probable central chemoreceptors. PMID:23080151

  2. Under Pressure: Mechanical Stress Management in the Nucleus

    PubMed Central

    Belaadi, Néjma; Aureille, Julien; Guilluy, Christophe

    2016-01-01

    Cells are constantly adjusting to the mechanical properties of their surroundings, operating a complex mechanochemical feedback, which hinges on mechanotransduction mechanisms. Whereas adhesion structures have been shown to play a central role in mechanotransduction, it now emerges that the nucleus may act as a mechanosensitive structure. Here, we review recent advances demonstrating that mechanical stress emanating from the cytoskeleton can activate pathways in the nucleus which eventually impact both its structure and the transcriptional machinery. PMID:27314389

  3. Axon terminals from the nucleus isthmi pars parvocellularis control the ascending retinotectofugal output through direct synaptic contact with tectal ganglion cell dendrites.

    PubMed

    González-Cabrera, Cristian; Garrido-Charad, Florencia; Mpodozis, Jorge; Bolam, J Paul; Marín, Gonzalo J

    2016-02-01

    The optic tectum in birds and its homologue the superior colliculus in mammals both send major bilateral, nontopographic projections to the nucleus rotundus and caudal pulvinar, respectively. These projections originate from widefield tectal ganglion cells (TGCs) located in layer 13 in the avian tectum and in the lower superficial layers in the mammalian colliculus. The TGCs characteristically have monostratified arrays of brush-like dendritic terminations and respond mostly to bidimensional motion or looming features. In birds, this TGC-mediated tectofugal output is controlled by feedback signals from the nucleus isthmi pars parvocellularis (Ipc). The Ipc neurons display topographically organized axons that densely ramify in restricted columnar terminal fields overlapping various neural elements that could mediate this tectofugal control, including the retinal terminals and the TGC dendrites themselves. Whether the Ipc axons make synaptic contact with these or other tectal neural elements remains undetermined. We double labeled Ipc axons and their presumptive postsynaptic targets in the tectum of chickens (Gallus gallus) with neural tracers and performed an ultrastructural analysis. We found that the Ipc terminal boutons form glomerulus-like structures in the superficial and intermediate tectal layers, establishing asymmetric synapses with several dendritic profiles. In these glomeruli, at least two of the postsynaptic dendrites originated from TGCs. We also found synaptic contacts between retinal terminals and TGC dendrites. These findings suggest that, in birds, Ipc axons control the ascending tectal outflow of retinal signals through direct synaptic contacts with the TGCs. PMID:26224333

  4. Intracellular Recordings From Combination-Sensitive Neurons in the Inferior Colliculus

    PubMed Central

    Peterson, Diana Coomes; Voytenko, Sergiy; Gans, Donald; Galazyuk, Alexander; Wenstrup, Jeffrey

    2008-01-01

    In vertebrate auditory systems, specialized combination-sensitive neurons analyze complex vocal signals by integrating information across multiple frequency bands. We studied combination-sensitive interactions in neurons of the inferior colliculus (IC) of awake mustached bats, using intracellular somatic recording with sharp electrodes. Facilitated combinatorial neurons are coincidence detectors, showing maximum facilitation when excitation from low- and high-frequency stimuli coincide. Previous work showed that facilitatory interactions originate in the IC, require both low and high frequency–tuned glycinergic inputs, and are independent of glutamatergic inputs. These results suggest that glycinergic inputs evoke facilitation through either postinhibitory rebound or direct depolarizing mechanisms. However, in 35 of 36 facilitated neurons, we observed no evidence of low frequency–evoked transient hyperpolarization or depolarization that was closely related to response facilitation. Furthermore, we observed no evidence of shunting inhibition that might conceal inhibitory inputs. Since these facilitatory interactions originate in IC neurons, the results suggest that inputs underlying facilitation are electrically segregated from the soma. We also recorded inhibitory combinatorial interactions, in which low frequency sounds suppress responses to higher frequency signals. In 43% of 118 neurons, we observed low frequency–evoked hyperpolarizations associated with combinatorial inhibition. For these neurons, we conclude that low frequency–tuned inhibitory inputs terminate on neurons primarily excited by high-frequency signals; these inhibitory inputs may create or enhance inhibitory combinatorial interactions. In the remainder of inhibited combinatorial neurons (57%), we observed no evidence of low frequency–evoked hyperpolarizations, consistent with observations that inhibitory combinatorial responses may originate in lateral lemniscal nuclei. PMID:18497365

  5. The superior colliculus is sensitive to gestalt-like stimulus configuration in hemispherectomy patients.

    PubMed

    Georgy, Loraine; Celeghin, Alessia; Marzi, Carlo A; Tamietto, Marco; Ptito, Alain

    2016-08-01

    Patients with cortical blindness following a lesion to the primary visual cortex (V1) may retain nonconscious visual abilities (blindsight). One intriguing, though largely unexplored question, is whether nonconscious vision in the blind hemifield of hemianopic patients can be sensitive to higher-order perceptual organization, and which V1-independent structure underlies such effect. To answer this question, we tested two rare hemianopic patients who had undergone hemispherectomy, and in whom the only post-chiasmatic visual structure left intact in the same side of the otherwise damaged hemisphere was the superior colliculus (SC). By using a variant of the redundant target effect (RTE), we presented single dots, patterns composed by the same dots organized in quadruple gestalt-like configurations, or patterns of four dots arranged in random configurations, either singly to the intact visual hemifield or bilaterally to both hemifields. As reported in a number of prior studies on blindsight patients, we found that bilateral stimulation yielded faster reaction times (RTs) than single stimulation of the intact field for all conditions (i.e., there was an implicit RTE). In addition to this effect, both patients showed a further speeding up of RTs when the gestalt-like, but not the random shape, quadruple patterns were projected to their blind hemifield during bilateral stimulation. Because other retino-recipient subcortical and cortical structures in the damaged hemisphere are absent, the SC on the lesioned side seems solely responsible for such an effect. The present results provide initial support to the notion that nonconscious vision might be sensitive to perceptual organization and stimulus configuration through the pivotal contribution of the SC, which can enhance the processing of gestalt-like or structured stimuli over meaningless or randomly assembled ones and translate them into facilitatory motor outputs. PMID:27208816

  6. The morphology of optic tract axons arborizing in the superior colliculus of the hamster.

    PubMed

    Sachs, G M; Schneider, G E

    1984-12-01

    Single axons innervating the superficial layers of the hamster's superior colliculus (SC) were visualized using an HRP-filling technique. Five types of axons were distinguished. Experiments involving the removal of retinal and/or cortical input showed that three of these axon types originated in the contralateral retina with the fourth type most likely originating in the visual cortex. The origin of the fifth type, a widely branched varicose axon, is apparently subcortical. The two major types of presumed retinotectal axons (types U and L1) project to the stratum griseum superficiale (SGS) in a bilaminar pattern. Type U axons take relatively direct paths from the layer of optic fibers to form dense terminal arbors in the upper half of the SGS. Terminal fields for type U fibers showed fairly consistent dimensions. Their rostrocaudal extent ranged from 90 micron to 190 micron, averaging about 120 micron. Type L1 axons were thicker than type U axons and terminated in deeper regions of the SGS and in the stratum opticum (SO). Single axons of this type often gave rise to multiple branches which took separate, circuitous paths to a common terminal field. Terminal fields for type L1 axons varied more in extent than did type U fields, but 58% of them had fields 90-150 micron in extent. Each of the axon types found can be related to previous studies of populations of tectal afferents. The two major types of retinofugal axons fit a scheme of parallel ascending pathways. The findings also have interesting implications for the study of axonal development. PMID:6512015

  7. Immunocytochemical Localization of Calbindin D28K, Calretinin, and Parvalbumin in Bat Superior Colliculus

    PubMed Central

    Jeong, Se-Jin; Kim, Hyun-Ho; Lee, Won-Sig; Jeon, Chang-Jin

    2014-01-01

    The purpose of this study was to investigate the localization of cells containing the calcium-binding proteins (CBPs) calbindin D28K (CB), calretinin (CR), and parvalbumin (PV) in the superior colliculus (SC) of the bat using immunocytochemistry. CB-immunoreactive (IR) cells formed a laminar tier within the upper superficial gray layer (SGL), while CR-IR cells were widely distributed within the optic layer (OL). Scattered CR-IR cells were also found within the intermediate gray, white, and deep gray layers. By contrast, PV-IR cells formed a laminar tier within the lower SGL and upper OL. Scattered PV-IR cells were also found throughout the intermediate layers, but without a specific laminar pattern. The CBP-IR cells varied in size and morphology: While most of the CB-IR cells in the superficial layers were small round or oval cells, most CR-IR cells in the intermediate and deep layers were large stellate cells. By contrast, PV-IR cells were small to large in size and included round or oval, stellate, vertical fusiform, and horizontal cells. The average diameters of the CB-, CR-, and PV-IR cells were 11.59, 17.17, and 12.60 μm, respectively. Double-immunofluorescence revealed that the percentage of co-localization with GABA-IR cells was 0.0, 0.0, and 10.27% of CB-, CR-, and PV-IR cells, respectively. These results indicate that CBP distribution patterns in the bat SC are unique compared with other mammalian SCs, which suggest functional diversity of these proteins in visually guided behaviors. PMID:25320408

  8. An animal model of disengagement: Temporary inactivation of the superior colliculus impairs attention disengagement in rats.

    PubMed

    de Araujo, Mariana Ferreira Pereira; Matsumoto, Jumpei; Ono, Taketoshi; Nishijo, Hisao

    2015-10-15

    The orienting attention network is responsible for prioritizing sensory input through overt or covert shifts of attention among targets. The ability to disengage attention is essential for the proper functioning of this network. In addition to its importance for proper orienting, deficits in disengagement have been recently implicated in autism disorders. Despite its importance, the neural mechanisms underlying disengagement processing are still poorly understood. In this study, the involvement of the superior colliculus (SC) in disengagement was investigated in unrestrained rats that had been trained in a two-alternative light-guided spatial choice task. At each trial, the rats had to choose one of two paths, leading either to a large or a small reward, based on 1 (single-cue) or 2 (double-cue) lights. The task consisted of serial trials with single- and/or double-cue lights, and rats could acquire a large reward if the rats chose infrequent lights when infrequent cue lights were presented after preceding frequent cue lights. Experiment 1 included trials with either single- or double-cue lights, and infrequent trials with double-cue lights required both attentional disengagement and shift of attention from preceding frequent single-cue lights, while experiment 2 included only trials with single-cue lights requiring shifts of attention but not attentional disengagement. The results indicated that temporary inactivation of the SC by muscimol injections selectively impaired performance on trials requiring disengagement. No impairment was observed on the other trials, in which attention disengagement was not required. The results provide the first evidence that the SC is necessary for attentional disengagement. PMID:26196954

  9. NMDA Antagonists in the Superior Colliculus Prevent Developmental Plasticity But Not Visual Transmission or Map Compression

    PubMed Central

    HUANG, L.; PALLAS, S. L.

    2016-01-01

    Partial ablation of the superior colliculus (SC) at birth in hamsters compresses the retinocollicular map, increasing the amount of visual field represented at each SC location. Receptive field sizes of single SC neurons are maintained, however, preserving receptive field properties in the prelesion condition. The mechanism that allows single SC neurons to restrict the number of convergent retinal inputs and thus compensate for induced brain damage is unknown. In this study, we examined the role of N-methyl-d-aspartate (NMDA) receptors in controlling retinocollicular convergence. We found that chronic 2-amino-5-phosphonovaleric acid (APV) blockade of NMDA receptors from birth in normal hamsters resulted in enlarged single-unit receptive fields in SC neurons from normal maps and further enlargement in lesioned animals with compressed maps. The effect was linearly related to lesion size. These results suggest that NMDA receptors are necessary to control afferent/target convergence in the normal SC and to compensate for excess retinal afferents in lesioned animals. Despite the alteration in receptive field size in the APV-treated animals, a complete visual map was present in both normal and lesioned hamsters. Visual responsiveness in the treated SC was normal; thus the loss of compensatory plasticity was not due to reduced visual responsiveness. Our results argue that NMDA receptors are essential for map refinement, construction of receptive fields, and compensation for damage but not overall map compression. The results are consistent with a role for the NMDA receptor as a coincidence detector with a threshold, providing visual neurons with the ability to calculate the amount of visual space represented by competing retinal inputs through the absolute amount of coincidence in their firing patterns. This mechanism of population matching is likely to be of general importance during nervous system development. PMID:11535668

  10. Molecular features distinguish ten neuronal types in the mouse superficial superior colliculus.

    PubMed

    Byun, Haewon; Kwon, Soohyun; Ahn, Hee-Jeong; Liu, Hong; Forrest, Douglas; Demb, Jonathan B; Kim, In-Jung

    2016-08-01

    The superior colliculus (SC) is a midbrain center involved in controlling head and eye movements in response to inputs from multiple sensory modalities. Visual inputs arise from both the retina and visual cortex and converge onto the superficial layer of the SC (sSC). Neurons in the sSC send information to deeper layers of the SC and to thalamic nuclei that modulate visually guided behaviors. Presently, our understanding of sSC neurons is impeded by a lack of molecular markers that define specific cell types. To better understand the identity and organization of sSC neurons, we took a systematic approach to investigate gene expression within four molecular families: transcription factors, cell adhesion molecules, neuropeptides, and calcium binding proteins. Our analysis revealed 12 molecules with distinct expression patterns in mouse sSC: cadherin 7, contactin 3, netrin G2, cadherin 6, protocadherin 20, retinoid-related orphan receptor β, brain-specific homeobox/POU domain protein 3b, Ets variant gene 1, substance P, somatostatin, vasoactive intestinal polypeptide, and parvalbumin. Double labeling experiments, by either in situ hybridization or immunostaining, demonstrated that the 12 molecular markers collectively define 10 different sSC neuronal types. The characteristic positions of these cell types divide the sSC into four distinct layers. The 12 markers identified here will serve as valuable tools to examine molecular mechanisms that regulate development of sSC neuronal types. These markers could also be used to examine the connections between specific cell types that form retinocollicular, corticocollicular, or colliculothalamic pathways. J. Comp. Neurol. 524:2300-2321, 2016. © 2016 Wiley Periodicals, Inc. PMID:26713509

  11. Development of cortical influences on superior colliculus multisensory neurons: Effects of dark-rearing

    PubMed Central

    Yu, Liping; Xu, Jinghong; Rowland, Benjamin A.; Stein, Barry E.

    2013-01-01

    Rearing cats from birth to adulthood in darkness prevents neurons in the superior colliculus (SC) from developing the capability to integrate visual and non-visual (e.g., visual-auditory) inputs. Presumably, this developmental anomaly is due to a lack of experience with the combination of those cues, which is essential to form associative links between them. The visual-auditory multisensory integration capacity of SC neurons has also been shown to depend on the functional integrity of converging visual and auditory inputs from ipsilateral association cortex. Disrupting these cortico-collicular projections at any stage of life results in a pattern of outcomes similar to those found after dark-rearing: SC neurons respond to stimuli in both sensory modalities, but cannot integrate the information they provide. Thus, it is possible that dark-rearing compromises the development of these descending tectopetal connections and the essential influences they convey. However, the results of the present experiments, using cortical deactivation to assess the presence of cortico-collicular influences, demonstrate that dark-rearing does not prevent association cortex from developing robust influences over SC multisensory responses. In fact, dark-rearing may increase their potency over that observed in normally-reared animals. Nevertheless, their influences are still insufficient to support SC multisensory integration. It appears that cross-modal experience shapes the cortical influence to selectively enhance responses to cross-modal stimulus combinations that are likely to be derived from the same event. In the absence of this experience, the cortex develops an indiscriminate excitatory influence over its multisensory SC target neurons. PMID:23534923

  12. Glutamatergic neurotransmission in the inferior colliculus influences intrastriatal haloperidol-induced catalepsy.

    PubMed

    Medeiros, P; Viana, M B; Barbosa-Silva, R C; Tonelli, L C; Melo-Thomas, L

    2014-07-15

    The inferior colliculus (IC) is an important midbrain relay station for the integration of descending and ascending auditory information. In addition, it has also been implicated in the processing of acoustic information of aversive nature, as well as in sensory-motor gating. There is evidence that glutamate-mediated mechanisms at the IC level influence haloperidol-induced catalepsy. The present study investigated the influence of glutamate-mediated mechanisms in the IC on catalepsy induced by intrastriatal microinjection of haloperidol (10 μg/0.5 μl). Male Wistar rats received bilateral intracollicular microinjections of the glutamate receptor agonist NMDA (10 or 20 nmol/0.5 μl), the NMDA receptor antagonists MK-801 (15 or 30 nmol/0.5 μl) or physiological saline (0.5 μl), followed by bilateral microinjections of haloperidol (10 μg/0.5 μl) or vehicle (0.5 μl) into the dorso-rostral or ventro-rostral striatum. The catalepsy test was performed positioning both forepaws of the rats on an elevated horizontal wooden bar and recording the time during which the animal remained in this position. The results showed that the administration of physiological saline in the IC followed by the microinjection of haloperidol in the dorso-rostral region of the striatum was not able to induce catalepsy. However, when the bilateral administration of NMDA into the IC was followed by microinjection of haloperidol into the dorso-rostral striatum, catalepsy was observed. The microinjection of haloperidol into the ventro-rostral striatum induced catalepsy, counteracted by previous administration of MK-801 into the IC. These findings suggest that glutamate-mediated mechanisms in the IC can influence the intrastriatal haloperidol-induced catalepsy and that the IC plays an important role as a sensorimotor interface. PMID:24667361

  13. Intralaminar stimulation of the inferior colliculus facilitates frequency-specific activation in the auditory cortex

    NASA Astrophysics Data System (ADS)

    Allitt, B. J.; Benjaminsen, C.; Morgan, S. J.; Paolini, A. G.

    2013-08-01

    Objective. Auditory midbrain implants (AMI) provide inadequate frequency discrimination for open set speech perception. AMIs that can take advantage of the tonotopic laminar of the midbrain may be able to better deliver frequency specific perception and lead to enhanced performance. Stimulation strategies that best elicit frequency specific activity need to be identified. This research examined the characteristic frequency (CF) relationship between regions of the auditory cortex (AC), in response to stimulated regions of the inferior colliculus (IC), comparing monopolar, and intralaminar bipolar electrical stimulation. Approach. Electrical stimulation using multi-channel micro-electrode arrays in the IC was used to elicit AC responses in anaesthetized male hooded Wistar rats. The rate of activity in AC regions with CFs within 3 kHz (CF-aligned) and unaligned CFs was used to assess the frequency specificity of responses. Main results. Both monopolar and bipolar IC stimulation led to CF-aligned neural activity in the AC. Altering the distance between the stimulation and reference electrodes in the IC led to changes in both threshold and dynamic range, with bipolar stimulation with 400 µm spacing evoking the lowest AC threshold and widest dynamic range. At saturation, bipolar stimulation elicited a significantly higher mean spike count in the AC at CF-aligned areas than at CF-unaligned areas when electrode spacing was 400 µm or less. Bipolar stimulation using electrode spacing of 400 µm or less also elicited a higher rate of elicited activity in the AC in both CF-aligned and CF-unaligned regions than monopolar stimulation. When electrodes were spaced 600 µm apart no benefit over monopolar stimulation was observed. Furthermore, monopolar stimulation of the external cortex of the IC resulted in more localized frequency responses than bipolar stimulation when stimulation and reference sites were 200 µm apart. Significance. These findings have implications for the

  14. Defense-like behaviors evoked by pharmacological disinhibition of the superior colliculus in the primate

    PubMed Central

    DesJardin, Jacqueline T.; Holmes, Angela L.; Forcelli, Patrick A.; Cole, Claire E.; Gale, John T.; Wellman, Laurie L.; Gale, Karen; Malkova, Ludise

    2012-01-01

    Stimulation of the intermediate and deep layers of superior colliculus (DLSC) in rodents evokes both tracking/pursuit (approach) and avoidance/flight (defensive) responses (Dean et al., 1989). These two classes of response are subserved by distinct output projections associated with lateral (approach) and medial (defensive) DLSC (Comoli et al., 2012). In nonhuman primates, DLSC has been examined only with respect to orienting/approach behaviors, especially eye movements, however, defense-like behaviors have not been reported. Here we examined the profile of behavioral responses to the activation of DLSC by unilateral intracerebral infusions of the GABAA receptor antagonist, bicuculline methiodide (BIC), in nine freely moving macaques. Across animals, the most consistently evoked behavior was cowering (all animals), followed by increased vocalization and escape-like behaviors (seven animals), and attack of objects (three animals). The effects of BIC were dose-dependent within the range 2.5-14nmol (threshold dose of 4.6nmol). The behaviors and their latency to onset did not vary across different infusion sites within DLSC. Cowering and escape-like behaviors resembled the defense-like responses reported after DLSC stimulation in rats, but in the macaques these responses were evoked from both medial and lateral sites within DLSC. Our findings are unexpected in the context of an earlier theoretical perspective (Dean et al., 1989) that emphasized a preferential role of the primate DLSC for approach rather than defensive responses. Our data provide the first evidence for induction of defense-like behaviors by activation of DLSC in monkeys, suggesting that the role of DLSC in responding to threats is conserved across species. PMID:23283329

  15. Temporal features of spectral integration in the inferior colliculus: effects of stimulus duration and rise time.

    PubMed

    Gans, Donald; Sheykholeslami, Kianoush; Peterson, Diana Coomes; Wenstrup, Jeffrey

    2009-07-01

    This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16-31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11-32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals<23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range-frequencies in the first sonar harmonic-generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway. PMID:19403742

  16. Neuronal correlates of attention and its disengagement in the superior colliculus of rat

    PubMed Central

    Ngan, Nguyen H.; Matsumoto, Jumpei; Takamura, Yusaku; Tran, Anh H.; Ono, Taketoshi; Nishijo, Hisao

    2015-01-01

    Orienting attention to a new target requires prior disengagement of attention from the current focus. Previous studies indicate that the superior colliculus (SC) plays an important role in attention. However, recordings of responses of SC neurons during attentional disengagement have not yet been reported. Here, we analyzed rat SC neuronal activity during performance of an attention-shift task with and without disengagement. In this task, conditioned stimuli (CSs; right and/or left light-flash or sound) were sequentially presented. To obtain an intracranial self-stimulation reward, rats were required to lick a spout when an infrequent conditioned stimulus appeared (reward trials). In the disengagement reward trials, configural stimuli consisting of an infrequent stimulus and frequent stimulus in the former trials were presented; in the non-disengagement reward trials, only an infrequent stimulus was presented. Of the 186 SC neurons responding to the CSs, 41 showed stronger responses to the CSs in the disengagement reward trials than in the non-disengagement reward trials (disengagement-related neurons). Furthermore, lick latencies in the disengagement reward trials were negatively correlated with response magnitudes to the CSs in half of the disengagement-related neurons. These disengagement-related neurons were located mainly in the deep layers of the SC. Another 70 SC neurons responded to the CSs in both disengagement and non-disengagement reward trials, suggesting that these neurons were involved in attention engagement. Our results suggest complementary mechanisms of attentional shift based on two subpopulations of neurons in the SC. PMID:25741252

  17. Neuronal responses to face-like and facial stimuli in the monkey superior colliculus

    PubMed Central

    Nguyen, Minh Nui; Matsumoto, Jumpei; Hori, Etsuro; Maior, Rafael Souto; Tomaz, Carlos; Tran, Anh H.; Ono, Taketoshi; Nishijo, Hisao

    2014-01-01

    The superficial layers of the superior colliculus (sSC) appear to function as a subcortical visual pathway that bypasses the striate cortex for the rapid processing of coarse facial information. We investigated the responses of neurons in the monkey sSC during a delayed non-matching-to-sample (DNMS) task in which monkeys were required to discriminate among five categories of visual stimuli [photos of faces with different gaze directions, line drawings of faces, face-like patterns (three dark blobs on a bright oval), eye-like patterns, and simple geometric patterns]. Of the 605 sSC neurons recorded, 216 neurons responded to the visual stimuli. Among the stimuli, face-like patterns elicited responses with the shortest latencies. Low-pass filtering of the images did not influence the responses. However, scrambling of the images increased the responses in the late phase, and this was consistent with a feedback influence from upstream areas. A multidimensional scaling (MDS) analysis of the population data indicated that the sSC neurons could separately encode face-like patterns during the first 25-ms period after stimulus onset, and stimulus categorization developed in the next three 25-ms periods. The amount of stimulus information conveyed by the sSC neurons and the number of stimulus-differentiating neurons were consistently higher during the 2nd to 4th 25-ms periods than during the first 25-ms period. These results suggested that population activity of the sSC neurons preferentially filtered face-like patterns with short latencies to allow for the rapid processing of coarse facial information and developed categorization of the stimuli in later phases through feedback from upstream areas. PMID:24672448

  18. Three-dimensional eye-head coordination is implemented downstream from the superior colliculus.

    PubMed

    Klier, Eliana M; Wang, Hongying; Crawford, J Douglas

    2003-05-01

    How the brain transforms two-dimensional visual signals into multi-dimensional motor commands, and subsequently how it constrains the redundant degrees of freedom, are fundamental problems in sensorimotor control. During fixations between gaze shifts, the redundant torsional degree of freedom is determined by various neural constraints. For example, the eye- and head-in-space are constrained by Donders' law, whereas the eye-in-head obeys Listing's law. However, where and how the brain implements these laws is not yet known. In this study, we show that eye and head movements, elicited by unilateral microstimulations of the superior colliculus (SC) in head-free monkeys, obey the same Donders' strategies observed in normal behavior (i.e., Listing's law for final eye positions and the Fick strategy for the head). Moreover, these evoked movements showed a pattern of three-dimensional eye-head coordination, consistent with normal behavior, where the eye is driven purposely out of Listing's plane during the saccade portion of the gaze shift in opposition to a subsequent torsional vestibuloocular reflex slow phase, such that the final net torsion at the end of each head-free gaze shift is zero. The required amount of saccade-related torsion was highly variable, depending on the initial position of the eye and head prior to a gaze shift and the size of the gaze shift, pointing to a neural basis of torsional control. Because these variable, context-appropriate torsional saccades were correctly elicited by fixed SC commands during head-free stimulations, this shows that the SC only encodes the horizontal and vertical components of gaze, leaving the complexity of torsional organization to downstream control systems. Thus we conclude that Listing's and Donders' laws of the eyes and head, and their three-dimensional coordination mechanisms, must be implemented after the SC. PMID:12740415

  19. Sharper, Stronger, Faster Upper Visual Field Representation in Primate Superior Colliculus.

    PubMed

    Hafed, Ziad M; Chen, Chih-Yang

    2016-07-11

    Visually guided behavior in three-dimensional environments entails handling immensely different sensory and motor conditions across retinotopic visual field locations: peri-personal ("near") space is predominantly viewed through the lower retinotopic visual field (LVF), whereas extra-personal ("far") space encompasses the upper visual field (UVF). Thus, when, say, driving a car, orienting toward the instrument cluster below eye level is different from scanning an upcoming intersection, even with similarly sized eye movements. However, an overwhelming assumption about visuomotor circuits for eye-movement exploration, like those in the primate superior colliculus (SC), is that they represent visual space in a purely symmetric fashion across the horizontal meridian. Motivated by ecological constraints on visual exploration of far space, containing small UVF retinal-image features, here we found a large, multi-faceted difference in the SC's representation of the UVF versus LVF. Receptive fields are smaller, more finely tuned to image spatial structure, and more sensitive to image contrast for neurons representing the UVF. Stronger UVF responses also occur faster. Analysis of putative synaptic activity revealed a particularly categorical change when the horizontal meridian is crossed, and our observations correctly predicted novel eye-movement effects. Despite its appearance as a continuous layered sheet of neural tissue, the SC contains functional discontinuities between UVF and LVF representations, paralleling a physical discontinuity present in cortical visual areas. Our results motivate the recasting of structure-function relationships in the visual system from an ecological perspective, and also exemplify strong coherence between brain-circuit organization for visually guided exploration and the nature of the three-dimensional environment in which we function. PMID:27291052

  20. Monaural and Binaural Inhibition Underlying Duration-Tuned Neurons in the Inferior Colliculus

    PubMed Central

    Sayegh, Riziq; Casseday, John H.; Covey, Ellen

    2014-01-01

    Duration-tuned neurons (DTNs) in the mammalian inferior colliculus (IC) arise from a combination of excitatory and inhibitory synaptic inputs. Previous research has shown that the inhibition responsible for creating DTNs has a shorter latency than that of excitation and lasts longer than the stimulus duration. We used monotic and dichotic paired tone stimulation and recorded responses of DTNs from the IC of the bat to assess the relative contributions of each ear in forming duration-tuned circuits. The stimulus consisted of a short best duration (BD) excitatory tone and a longer duration nonexcitatory (NE) tone. In the monotic condition, when the BD and NE tones were presented to the contralateral ear and were sufficiently close in time, the NE tone always suppressed spikes evoked by the BD tone. In the dichotic condition, when the BD tone was presented to the contralateral ear and the NE tone to the ipsilateral ear, half of DTNs no longer showed spike suppression to the NE tone. Of those DTNs with suppression in both conditions, the latency of the inhibition was shorter and the duration of the inhibition was longer in the monotic condition. Therefore, in the monotic condition, DTNs received a contralaterally evoked inhibitory input that preceded the excitatory input to the same neuron. In the dichotic condition, DTNs received an ipsilaterally evoked inhibitory input that was weaker, longer in latency, and shorter in duration than the inputs from the contralateral ear. These findings indicate that the neural mechanisms that create DTNs in the IC are monaural. PMID:24403148

  1. Whisker motor cortex reorganization after superior colliculus output suppression in adult rats.

    PubMed

    Veronesi, Carlo; Maggiolini, Emma; Franchi, Gianfranco

    2013-10-01

    The effect of unilateral superior colliculus (SC) output suppression on the ipsilateral whisker motor cortex (WMC) was studied at different time points after tetrodotoxin and quinolinic acid injections, in adult rats. The WMC output was assessed by mapping the movement evoked by intracortical microstimulation (ICMS) and by recording the ICMS-evoked electromyographic (EMG) responses from contralateral whisker muscles. At 1 h after SC injections, the WMC showed: (i) a strong decrease in contralateral whisker sites, (ii) a strong increase in ipsilateral whisker sites and in ineffective sites, and (iii) a strong increase in threshold current values. At 6 h after injections, the WMC size had shrunk to 60% of the control value and forelimb representation had expanded into the lateral part of the normal WMC. Thereafter, the size of the WMC recovered, returning to nearly normal 12 h later (94% of control) and persisted unchanged over time (1-3 weeks). The ICMS-evoked EMG response area decreased at 1 h after SC lesion and had recovered its baseline value 12 h later. Conversely, the latency of ICMS-evoked EMG responses had increased by 1 h and continued to increase for as long as 3 weeks following the lesion. These findings provide physiological evidence that SC output suppression persistently withdrew the direct excitatory drive from whisker motoneurons and induced changes in the WMC. We suggest that the changes in the WMC are a form of reversible short-term reorganization that is induced by SC lesion. The persistent latency increase in the ICMS-evoked EMG response suggested that the recovery of basic WMC excitability did not take place with the recovery of normal explorative behaviour. PMID:23895333

  2. Effect of current focusing on the sensitivity of inferior colliculus neurons to amplitude-modulated stimulation.

    PubMed

    George, Shefin S; Shivdasani, Mohit N; Fallon, James B

    2016-09-01

    In multichannel cochlear implants (CIs), current is delivered to specific electrodes along the cochlea in the form of amplitude-modulated pulse trains, to convey temporal and spectral cues. Our previous studies have shown that focused multipolar (FMP) and tripolar (TP) stimulation produce more restricted neural activation and reduced channel interactions in the inferior colliculus (IC) compared with traditional monopolar (MP) stimulation, suggesting that focusing of stimulation could produce better transmission of spectral information. The present study explored the capability of IC neurons to detect modulated CI stimulation with FMP and TP stimulation compared with MP stimulation. The study examined multiunit responses of IC neurons in acutely deafened guinea pigs by systematically varying the stimulation configuration, modulation depth, and stimulation level. Stimuli were sinusoidal amplitude-modulated pulse trains (carrier rate of 120 pulses/s). Modulation sensitivity was quantified by measuring modulation detection thresholds (MDTs), defined as the lowest modulation depth required to differentiate the response of a modulated stimulus from an unmodulated one. Whereas MP stimulation showed significantly lower MDTs than FMP and TP stimulation (P values <0.05) at stimulation ≤2 dB above threshold, all stimulation configurations were found to have similar modulation sensitivities at 4 dB above threshold. There was no difference found in modulation sensitivity between FMP and TP stimulation. The present study demonstrates that current focusing techniques such as FMP and TP can adequately convey amplitude modulation and are comparable to MP stimulation, especially at higher stimulation levels, although there may be some trade-off between spectral and temporal fidelity with current focusing stimulation. PMID:27306672

  3. [EFFECT OF HYPOXIA ON SYNAPTIC TRANSMISSION BETWEEN RETINAL GANGLION CELLS AND SUPERIOR COLLICULUS NEURONS IN COCULTURE].

    PubMed

    Dumanska, G V; Rikhalsky, O V; Veselovsky, N S

    2015-01-01

    In this study we conducted a series of experiments to characterize the effect and define the mechanisms of hypoxia on synaptic transmission between retinal ganglion cells and superior colliculus (SC) neurons. Application of hypoxic solution leads to a long lasting potentiation (LTP) NMDA-mediated synaptic transmission. Analysis of the oxygen deficiency effect on the spontaneous and miniature postsynaptic currents (sPSC and mPSC respectively) revealed an increase in the frequency of their occurrence and the appearance of the second peak in the mPSC histogram distribution. The assessment of quantum and binomial parameters reflects the complex pre- and postsynaptic changes during the potentiation, independent of the release probability. Most likely this LTP can be caused by an increase in the total number of active synapses. Glutamatergic synaptic transmission mediated by non-NMDA activation receptor-channel complexes, responded to application of deoxygenated solution by the brief depression, which is the result of presynaptic dysfunction and associates with decrease in release probability and number of active zones. GABAergic synaptic transmission mediated by activation GABA(A)-receptor-channel complexes, responded to hypoxic action by long term depression (LTD). Analysis of sPSC and mPSC showed a significant decrease in the frequency of their occurrence and significant (P = 0.05) decrease in the quantum over a period of oxygen deficiency. In general, the effect of hypoxia-induced LTD of GABAergic synaptic transmission is based on complex changes of presynaptic (independent on the release probability) and postsynaptic (reduction sensitivity of receptors in postsynaptic membrane) mechanisms. PMID:27025053

  4. Dopamine modulates auditory responses in the inferior colliculus in a heterogeneous manner.

    PubMed

    Gittelman, Joshua X; Perkel, David J; Portfors, Christine V

    2013-10-01

    Perception of complex sounds such as speech is affected by a variety of factors, including attention, expectation of reward, physiological state, and/or disorders, yet the mechanisms underlying this modulation are not well understood. Although dopamine is commonly studied for its role in reward-based learning and in disorders, multiple lines of evidence suggest that dopamine is also involved in modulating auditory processing. In this study, we examined the effects of dopamine application on neuronal response properties in the inferior colliculus (IC) of awake mice. Because the IC contains dopamine receptors and nerve terminals immunoreactive for tyrosine hydroxylase, we predicted that dopamine would modulate auditory responses in the IC. We recorded single-unit responses before, during, and after the iontophoretic application of dopamine using piggyback electrodes. We examined the effects of dopamine on firing rate, timing, and probability of bursting. We found that application of dopamine affected neural responses in a heterogeneous manner. In more than 80 % of the neurons, dopamine either increased (32 %) or decreased (50 %) firing rate, and the effects were similar on spontaneous and sound-evoked activity. Dopamine also either increased or decreased first spike latency and jitter in almost half of the neurons. In 3/28 neurons (11 %), dopamine significantly altered the probability of bursting. The heterogeneous effects of dopamine observed in the IC of awake mice were similar to effects observed in other brain areas. Our findings indicate that dopamine differentially modulates neural activity in the IC and thus may play an important role in auditory processing. PMID:23835945

  5. Analytic optical potentials for nucleon-nucleus nucleus-nucleus collisions involving light and medium nuclei

    NASA Technical Reports Server (NTRS)

    Bidasaria, H. B.; Townsend, L. W.

    1982-01-01

    Utilizing an optical model potential approximation to the exact nucleus-nucleus multiple-scattering series, optical potentials for nucleon-nucleus and nucleus-nucleus collisions are analytically derived. These expressions are applicable to light and medium cosmic ray nuclei as their single-particle density distributions are analytically determined, without approximation, from their actual harmonic well charge density distributions. Pauli correlation effects are included through the use of a simple Gaussian function to replace the usual expression obtained in the infinite nuclear matter approximation.

  6. Projections of nucleus caudalis and spinal cord to brainstem and diencephalon in the hedgehog (Erinaceus europaeus and Paraechinus aethiopicus): a degeneration study.

    PubMed

    Ring, G; Ganchrow, D

    1983-05-10

    In the light of hypotheses related to the evolution of pain-carrying systems in mammals, terminal projection fields in brainstem and diencephalon of efferents of nucleus caudalis (NC) of the spinal trigeminal complex and spinal cord were determined in hedgehog by using Nauta-Gygax and Fink-Heimer silver techniques for degeneration. Unilateral NC lesions resulted in medullary degeneration in the ventral portion of NC contralaterally and bilaterally in cuneate nucleus (CU) and reticular formation. Pontine degeneration was noted ipsilaterally in medial (PBM) and lateral (PBL) parabrachial, facial motor (VII), and interpolar, oral, and main sensory trigeminal nuclei; degeneration in reticular formation was bilateral. Midbrain degeneration was seen bilaterally in caudal superior colliculus (SC), inferior colliculus (IC), periaqueductal gray, and tegmentum. In thalamus, projections to ventroposterior nucleus (VP) were contralateral and concentrated in a crescent extending along the lateral one-third-to-one-half and ventral border of the nucleus. Bilateral degeneration fields were noted in a dorsomedial sector of the "ventral nuclear field," posterior complex (PO), and mediodorsal nucleus (MD), the degeneration always heavier contralaterally in these nuclei. Sparse degeneration was noted in the medial most portions of the medial geniculate nuclei bordering PO and VP. In rostral diencephalon, bilateral degeneration was traced from the inferior thalamic peduncle to the lateral hypothalamic area (LH). Unilateral spinal cord lesions made between C7 and T1 vertebrae resulted in medullary degeneration in NC contralaterally, ipsilaterally in CU and lateral cuneate nucleus, and bilaterally in gracile nucleus, inferior olivary complex, and reticular formation. Pontine degeneration was limited to ipsilateral PBL and bilaterally to VII. Midbrain degeneration was found bilaterally in IC, SC, nucleus sagulum, and tegmentum; a minor projection was noted in interpeduncular nucleus. In

  7. Hierarchically clustering to 1,033 genes differentially expressed in mouse superior colliculus in the courses of optic nerve development and injury.

    PubMed

    Mei, Qiang; Zhang, Yan-qi; Liu, Jian-jun; Li, Cheng-ren; Chen, Xing-shu; Li, Hong-li; Qin, Mao-lin; wu, Ya-zhou; Liu, Yun-lai; Cai, Wen-qin

    2013-11-01

    Tempo spatially specific expression of many development-related genes is the molecular basis for the formation of the central nervous system (CNS), especially those genes regulating the proliferation, differentiation, migration, axon growth, and orientation of nerve cells. The development-related genes are usually prominent during the embryonic and newborn stages, but rarely express during the adulthood. These genes are believed to be suitable target genes for promoting CNS regeneration, despite majority of which remains unknown. Hence, the aim of this study was to screen development-related genes which might contribute to CNS regeneration. In this study, 1,033 differentially-expressed genes of superior colliculus in the courses of mouse optic nerve development and injury, as previously identified by cDNA microarrays, were hierarchically clustered to display expression pattern of each gene and reveal the relationships among these genes, and infer the functions of some unknown genes based on function-identified genes with the similar expression patterns. Consequently, the expression patterns of 1,033 candidate genes were revealed at eight time points during optic nerve development or injury. According to the similarity among gene expression patterns, 1,033 genes were divided into seven groups. The potential function of genes in each group was inferred on the basis of the dynamic trend for mean gene expression values. Moreover, the expression patterns of six function-unidentified genes were extremely similar to that of the ptn gene which could promote and guide axonal extension. Therefore, these six genes are temporally regarded as candidate genes related to axon growth and guidance. The results may help to better understand the roles of function-identified genes in the stages of CNS development and injury, and offer useful clues to evaluate the functions of hundreds of unidentified genes. PMID:23526189

  8. Organization and trade-off of spectro-temporal tuning properties of duration-tuned neurons in the mammalian inferior colliculus

    PubMed Central

    Morrison, James A.; Farzan, Faranak; Fremouw, Thane; Sayegh, Riziq; Covey, Ellen

    2014-01-01

    Neurons throughout the mammalian central auditory pathway respond selectively to stimulus frequency and amplitude, and some are also selective for stimulus duration. First found in the auditory midbrain or inferior colliculus (IC), these duration-tuned neurons (DTNs) provide a potential neural mechanism for encoding temporal features of sound. In this study, we investigated how having an additional neural response filter, one selective to the duration of an auditory stimulus, influences frequency tuning and neural organization by recording single-unit responses and measuring the dorsal-ventral position and spectral-temporal tuning properties of auditory DTNs from the IC of the awake big brown bat (Eptesicus fuscus). Like other IC neurons, DTNs were tonotopically organized and had either V-shaped, U-shaped, or O-shaped frequency tuning curves (excitatory frequency response areas). We hypothesized there would be an interaction between frequency and duration tuning in DTNs, as electrical engineering theory for resonant filters dictates a trade-off in spectral-temporal resolution: sharp tuning in the frequency domain results in poorer resolution in the time domain and vice versa. While the IC is a more complex signal analyzer than an electrical filter, a similar operational trade-off could exist in the responses of DTNs. Our data revealed two patterns of spectro-temporal sensitivity and spatial organization within the IC: DTNs with sharp frequency tuning and broad duration tuning were located in the dorsal IC, whereas cells with wide spectral tuning and narrow temporal tuning were found in the ventral IC. PMID:24572091

  9. Functional changes in Tg P23H-1 rat retinal responses: differences between ON and OFF pathway transmission to the superior colliculus.

    PubMed

    Fransen, James W; Pangeni, Gobinda; Pyle, Ian S; McCall, Maureen A

    2015-10-01

    The morphological consequences of retinal photoreceptor degeneration are well documented. Much less is known about changes in visual function during degeneration and whether central visual structures directly reflect changes in retinal ganglion cell (RGC) function. To address this, we compared changes in visual function of RGCs and cells in the superior colliculus (SC) in transgenic (Tg) P23H-1 rats, a model of retinitis pigmentosa (RP), and wild-type (WT) rats at postnatal days 35-50 (P35-50) and P300. RGCs were classified on the basis of their responses to light: onset (ON), offset (OFF), or both (ON-OFF). The distribution of ON, OFF, and ON-OFF RGCs is similar between WT and P35 Tg P23H-1 rats. By P300, many Tg P23H-1 RGCs are nonresponsive (NR). At this age, there is a sharp decline in ON and ON-OFF RGCs, and the majority that remain are OFF RGCs. Spontaneous rhythmic activity was observed in many RGCs at P300, but only in OFF or NR RGCs. In the SC, WT and P50 Tg P23H-1 responses are similar. At P300, Tg P23H-1 ON SC responses declined but OFF responses increased. We examined postsynaptic glutamate receptor expression located on the bipolar cells (BC), where the ON and OFF pathways arise. At P150, metabotropic glutamate receptor 6 (mGluR6) expression is lower than in WT, consistent with a decrease in ON RGC responses. GluR4 expression, an ionotropic glutamate receptor associated with OFF BCs, appears similar to that in WT. The loss of ON responses in Tg P23H-1 RGCs and in the SC is conserved and related to reduced mGluR6 signaling. PMID:26245318

  10. Nucleus from string theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Morita, Takeshi

    2011-08-01

    In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass-number (A) dependence r∝A1/3 for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multibaryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1)×A1/3[fm], which is consistent with experiments.

  11. Neutrino-nucleus interactions

    SciTech Connect

    Gallagher, H.; Garvey, G.; Zeller, G.P.; /Fermilab

    2011-01-01

    The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.

  12. Nucleus-nucleus collisions at ultrarelativistic energies

    SciTech Connect

    Gustafsson, H.A.; Kampert, K.H.; Albrecht, R.; Awes, T.C.; Baktash, C.; Beckmann, P.; Berger, F.; Bock, R.; Claesson, G.; Clewing, G.

    1988-01-01

    Results are presented from 60 and 200 AGeV p, /sup 16/O and /sup 32/S projectiles with C, Cu, Ag and Au nuclei. Energy spectra are measured at zero degrees and transverse energy distributions in the pseudorapidity range from 2.4 to 5.5 are shown. The average transverse energy per participant is found to be almost independent of projectile-target mass. Transverse momentum distributions of inclusive photons and neutral pions at midrapidity were in addition measured with lead glass array. For all target projectile combinations an increase in average p/sub T/ is observed for small values of entropy, which is deduced from the central multiplicity density. Different from proton induced reactions 200 AGeV /sup 16/O + Au data show a plateau like region at large values of entropy density. 17 refs., 5 figs.

  13. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  14. Higgs-Boson Production in Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  15. Higgs-boson production in nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W. (Principal Investigator)

    1990-01-01

    Cross-section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two-photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two-photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  16. Do growth-stimulated retinal ganglion cell axons find their central targets after optic nerve injury? New insights by three-dimensional imaging of the visual pathway.

    PubMed

    Diekmann, Heike; Leibinger, Marco; Fischer, Dietmar

    2013-10-01

    Retinal ganglion cells (RGCs) do not normally regenerate injured axons. However, several strategies to transform RGCs into a potent regenerative state have been developed in recent years. Intravitreal CNTF application combined with conditional PTEN and SOCS3 deletion or zymosan-induced inflammatory stimulation together with cAMP analogue injection and PTEN-deletion in RGCs induce long-distance regeneration into the optic nerve of adult mice. A recent paper by the Benowitz group (de Lima et al.) claimed that the latter treatment enables full-length regeneration, with axons correctly navigating to their central target zones and partial recovery of visual behaviors. To gain a more detailed view of the extent and the trajectories of regenerating axons, Luo et al. applied a tissue clearing method and fluorescent microscopy to allow the tracing of naïve and regenerating RGC axons in whole ON and all the way to their brain targets. Using this approach, the authors found comparable axon regeneration in the optic nerve after both above-mentioned experimental treatments. Regeneration was accompanied by prevalent aberrant axon growth in the optic nerve and significant axonal misguidance at the optic chiasm. Less than 120 axons per animal reached the optic chiasm and only few entered the correct optic tract. Importantly, no axons reached visual targets in the olivary pretectal nucleus, the lateral geniculate nucleus or the superior colliculus, thereby contradicting and challenging previous claims by the Benowitz group. The data provided by Luo et al. rather suggest that potent stimulation of axonal growth per se is insufficient to achieve functional recovery and underscore the need to investigate regeneration-relevant axon guidance mechanisms in the mature visual system. PMID:23816572

  17. Networking the nucleus

    PubMed Central

    Rajapakse, Indika; Scalzo, David; Tapscott, Stephen J; Kosak, Steven T; Groudine, Mark

    2010-01-01

    The nuclei of differentiating cells exhibit several fundamental principles of self-organization. They are composed of many dynamical units connected physically and functionally to each other—a complex network—and the different parts of the system are mutually adapted and produce a characteristic end state. A unique cell-specific signature emerges over time from complex interactions among constituent elements that delineate coordinate gene expression and chromosome topology. Each element itself consists of many interacting components, all dynamical in nature. Self-organizing systems can be simplified while retaining complex information using approaches that examine the relationship between elements, such as spatial relationships and transcriptional information. These relationships can be represented using well-defined networks. We hypothesize that during the process of differentiation, networks within the cell nucleus rewire according to simple rules, from which a higher level of order emerges. Studying the interaction within and among networks provides a useful framework for investigating the complex organization and dynamic function of the nucleus. PMID:20664641

  18. Unveiling the nucleus of NGC 7172

    NASA Astrophysics Data System (ADS)

    Smajić, S.; Fischer, S.; Zuther, J.; Eckart, A.

    2012-08-01

    Aims: We present the results of near-infrared (NIR) H + K European Southern Observatory SINFONI integral field spectroscopy (IFS) of the Seyfert 2 galaxy NGC 7172. We investigate the central 800 pc, concentrating on excitation conditions, morphology, and stellar content. NGC 7172 was selected from a sample of the ten nearest Seyfert 2 galaxies from the Veron-Cetty & Veron catalogue. All objects were chosen as test cases for adaptive optics (AO) assisted observations that allow a detailed study (at high spatial and spectral resolution) of the nuclear and host environments. NGC 7172 has a prominent dustlane crossing the central galaxy region from east to west, which makes it an ideal candidate to investigate the effect of obscuration by strong galactic extinction on (active) galaxies and their classification. Methods: The NIR is less influenced by dust extinction than optical light and is sensitive to the mass-dominating stellar populations. SINFONI integral field spectroscopy combines NIR imaging and spectroscopy and provides us with the opportunity to analyze several emission and absorption lines to investigate the stellar populations and ionization mechanisms over the 4″ × 4″ field of view (FOV). Results: We present emission and absorption line measurements in the central 800 pc of NGC 7172. The detection of [Si vi] and broad Paα and Brγ components are clear signs of an accreting super-massive black hole hiding behind the prominent dustlane at visible wavelengths. Hot temperatures of about 1300 K are indicative of a dusty torus in the nuclear region. Narrow components of Paα and Brγ enable us to make an extinction measurement. Our measures of the molecular hydrogen lines, hydrogen recombination lines, and [Fe ii] indicate that the excitation of these lines is caused by an active galactic nucleus. The central region of the galactic disk is predominantly inhabited by gas, dust, and an old K-M type giant stellar population. The gaseous, molecular, and

  19. Electric quadrupole excitations in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1989-01-01

    Calculations are presented for electric quadrupole excitations in relativistic nucleus-nucleus collisions. The theoretical results are compared to an extensive data set and it is found that electric quadrupole effects provide substantial corrections to cross sections, especially for heavier nuclei.

  20. Meson multiplicity versus energy in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Atwater, T. W.; Freier, P. S.

    1986-01-01

    A systematic study of meson multiplicity as a function of energy at energies up to 100 GeV/u in nucleus-nucleus collisions has been made, using cosmic-ray data in nuclear emulsion. The data are consistent with simple nucleon-nucleon superposition models. Multiplicity per interacting nucleon in AA collisions does not appear to differ significantly from pp collisions.

  1. Scaling phenomenon in relativistic nucleus-nucleus collisions

    SciTech Connect

    Wong, C. Y.; Blankenbecler, R.

    1980-01-01

    New scaling variables for proton and pion production in relativistic nucleus-nucleus collisions are introduced which are the generalizations of the Feynmann scaling variable. They allow a simple description of the cross sections at forward and backward angles. 2 figures.

  2. Momentum loss in proton-nucleus and nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Khan, Ferdous; Townsend, Lawrence W.

    1993-01-01

    An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies.

  3. Functional magnetic resonance imaging confirms forward suppression for rapidly alternating sounds in human auditory cortex but not in the inferior colliculus.

    PubMed

    Uhlig, Christian Harm; Dykstra, Andrew R; Gutschalk, Alexander

    2016-05-01

    Forward suppression at the level of the auditory cortex has been suggested to subserve auditory stream segregation. Recent results in non-streaming stimulation contexts have indicated that forward suppression can also be observed in the inferior colliculus; whether this holds for streaming-related contexts remains unclear. Here, we used cardiac-gated fMRI to examine forward suppression in the inferior colliculus (and the rest of the human auditory pathway) in response to canonical streaming stimuli (rapid tone sequences comprised of either one repetitive tone or two alternating tones). The first stimulus is typically perceived as a single stream, the second as two interleaved streams. In different experiments using either pure tones differing in frequency or bandpass-filtered noise differing in inter-aural time differences, we observed stronger auditory cortex activation in response to alternating vs. repetitive stimulation, consistent with the presence of forward suppression. In contrast, activity in the inferior colliculus and other subcortical nuclei did not significantly differ between alternating and monotonic stimuli. This finding could be explained by active amplification of forward suppression in auditory cortex, by a low rate (or absence) of cells showing forward suppression in inferior colliculus, or both. PMID:26899342

  4. The Multiple Functions of T Stellate/Multipolar/Chopper Cells in the Ventral Cochlear Nucleus

    PubMed Central

    Oertel, Donata; Wright, Samantha; Cao, Xiao-Jie; Ferragamo, Michael; Bal, Ramazan

    2010-01-01

    Acoustic information is brought to the brain by auditory nerve fibers, all of which terminate in the cochlear nuclei, and is passed up the auditory pathway through the principal cells of the cochlear nuclei. A population of neurons variously known as T stellate, type I multipolar, planar multipolar, or chopper cells forms one of the major ascending auditory pathways through the brain stem. T Stellate cells are sharply tuned; as a population they encode the spectrum of sounds. In these neurons, phasic excitation from the auditory nerve is made more tonic by feed forward excitation, coactivation of inhibitory with excitatory inputs, relatively large excitatory currents through NMDA receptors, and relatively little synaptic depression. The mechanisms that make firing tonic also obscure the fine structure of sounds that is represented in the excitatory inputs from the auditory nerve and account for the characteristic chopping response patterns with which T stellate cells respond to tones. In contrast with other principal cells of the ventral cochlear nucleus (VCN), T stellate cells lack a low-voltage-activated potassium conductance and are therefore sensitive to small, steady, neuromodulating currents. The presence of cholinergic, serotonergic and noradrenergic receptors allows the excitability of these cells to be modulated by medial olivocochlear efferent neurons and by neuronal circuits associated with arousal. T Stellate cells deliver acoustic information to the ipsilateral dorsal cochlear nucleus (DCN), ventral nucleus of the trapezoid body (VNTB), periolivary regions around the lateral superior olivary nucleus (LSO), and to the contralateral ventral lemniscal nuclei (VNLL) and inferior colliculus (IC). It is likely that T stellate cells participate in feedback loops through both medial and lateral olivocochlear efferent neurons and they may be a source of ipsilateral excitation of the LSO. PMID:21056098

  5. The Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    Exciting new broadband observations of the galactic nucleus have placed the heart of the Milky Way under intense scrutiny in recent years. This has been due in part to the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The center of our Galaxy is now known to harbor the most compelling supermassive black hole candidate, weighing in at 3-4 million solar masses. Its nearby environment is comprised of a molecular dusty ring, clusters of evolved and young stars, diffuse hot gas, ionized gas streamers, and several supernova remnants. This chapter will focus on the physical makeup of this dynamic region and the feasibility of actually imaging the black hole's shadow in the coming decade with mm interferometry.

  6. Monkey superior colliculus represents rapid eye movements in a two-dimensional motor map.

    PubMed

    Hepp, K; Van Opstal, A J; Straumann, D; Hess, B J; Henn, V

    1993-03-01

    1. Although the eye has three rotational degrees of freedom, eye positions, during fixations, saccades, and smooth pursuit, with the head stationary and upright, are constrained to a plane by Listing's law. We investigated whether Listing's law for rapid eye movements is implemented at the level of the deeper layers of the superior colliculus (SC). 2. In three alert rhesus monkeys we tested whether the saccadic motor map of the SC is two dimensional, representing oculocentric target vectors (the vector or V-model), or three dimensional, representing the coordinates of the rotation of the eye from initial to final position (the quaternion or Q-model). 3. Monkeys made spontaneous saccadic eye movements both in the light and in the dark. They were also rotated about various axes to evoke quick phases of vestibular nystagmus, which have three degrees of freedom. Eye positions were measured in three dimensions with the magnetic search coil technique. 4. While the monkey made spontaneous eye movements, we electrically stimulated the deeper layers of the SC and elicited saccades from a wide range of initial positions. According to the Q-model, the torsional component of eye position after stimulation should be uniquely related to saccade onset position. However, stimulation at 110 sites induced no eye torsion, in line with the prediction of the V-model. 5. Activity of saccade-related burst neurons in the deeper layers of the SC was analyzed during rapid eye movements in three dimensions. No systematic eye-position dependence of the movement fields, as predicted by the Q-model, could be detected for these cells. Instead, the data fitted closely the predictions made by the V-model. 6. In two monkeys, both SC were reversibly inactivated by symmetrical bilateral injections of muscimol. The frequency of spontaneous saccades in the light decreased dramatically. Although the remaining spontaneous saccades were slow, Listing's law was still obeyed, both during fixations and

  7. Auditory signals evolve from hybrid- to eye-centered coordinates in the primate superior colliculus.

    PubMed

    Lee, Jungah; Groh, Jennifer M

    2012-07-01

    Visual and auditory spatial signals initially arise in different reference frames. It has been postulated that auditory signals are translated from a head-centered to an eye-centered frame of reference compatible with the visual spatial maps, but, to date, only various forms of hybrid reference frames for sound have been identified. Here, we show that the auditory representation of space in the superior colliculus involves a hybrid reference frame immediately after the sound onset but evolves to become predominantly eye centered, and more similar to the visual representation, by the time of a saccade to that sound. Specifically, during the first 500 ms after the sound onset, auditory response patterns (N = 103) were usually neither head nor eye centered: 64% of neurons showed such a hybrid pattern, whereas 29% were more eye centered and 8% were more head centered. This differed from the pattern observed for visual targets (N = 156): 86% were eye centered, <1% were head centered, and only 13% exhibited a hybrid of both reference frames. For auditory-evoked activity observed within 20 ms of the saccade (N = 154), the proportion of eye-centered response patterns increased to 69%, whereas the hybrid and head-centered response patterns dropped to 30% and <1%, respectively. This pattern approached, although did not quite reach, that observed for saccade-related activity for visual targets: 89% were eye centered, 11% were hybrid, and <1% were head centered (N = 162). The plainly eye-centered visual response patterns and predominantly eye-centered auditory motor response patterns lie in marked contrast to our previous study of the intraparietal cortex, where both visual and auditory sensory and motor-related activity used a predominantly hybrid reference frame (Mullette-Gillman et al. 2005, 2009). Our present findings indicate that auditory signals are ultimately translated into a reference frame roughly similar to that used for vision, but suggest that such signals might

  8. BOLD fMRI study of ultrahigh frequency encoding in the inferior colliculus.

    PubMed

    Gao, Patrick P; Zhang, Jevin W; Chan, Russell W; Leong, Alex T L; Wu, Ed X

    2015-07-01

    Many vertebrates communicate with ultrahigh frequency (UHF) vocalizations to limit auditory detection by predators. The mechanisms underlying the neural encoding of such UHF sounds may provide important insights for understanding neural processing of other complex sounds (e.g. human speeches). In the auditory system, sound frequency is normally encoded topographically as tonotopy, which, however, contains very limited representation of UHFs in many species. Instead, electrophysiological studies suggested that two neural mechanisms, both exploiting the interactions between frequencies, may contribute to UHF processing. Neurons can exhibit excitatory or inhibitory responses to a tone when another UHF tone is presented simultaneously (combination sensitivity). They can also respond to such stimulation if they are tuned to the frequency of the cochlear-generated distortion products of the two tones, e.g. their difference frequency (cochlear distortion). Both mechanisms are present in an early station of the auditory pathway, the midbrain inferior colliculus (IC). Currently, it is unclear how prevalent the two mechanisms are and how they are functionally integrated in encoding UHFs. This study investigated these issues with large-view BOLD fMRI in rat auditory system, particularly the IC. UHF vocalizations (above 40kHz), but not pure tones at similar frequencies (45, 55, 65, 75kHz), evoked robust BOLD responses in multiple auditory nuclei, including the IC, reinforcing the sensitivity of the auditory system to UHFs despite limited representation in tonotopy. Furthermore, BOLD responses were detected in the IC when a pair of UHF pure tones was presented simultaneously (45 & 55kHz, 55 & 65kHz, 45 & 65kHz, 45 & 75kHz). For all four pairs, a cluster of voxels in the ventromedial side always showed the strongest responses, displaying combination sensitivity. Meanwhile, voxels in the dorsolateral side that showed strongest secondary responses to each pair of UHF pure tones

  9. Comparison of visual receptive field properties of the superior colliculus and primary visual cortex in rats.

    PubMed

    Li, Xiaoyuan; Sun, Chaokui; Shi, Li

    2015-08-01

    The rat visual system comprises cortical and subcortical pathways. The receptive field properties of cells in the visual cortex have been extensively studied; however, the fundamental roles of the two circuits in visual information processing are not well understood. To address this question, we have applied quantitative methods to compare and characterize the spatiotemporal receptive field (RF) properties of neurons in primary visual cortex (V1) cells and superficial layers of the superior colliculus (SC) in rats by means of extracellular recordings. An analysis of visual stimulus processing revealed distinct functional characteristics of the two visual circuits. RF diameters of SC neurons were significantly larger than those of V1 cells. Most cells in both regions had high orientation selectivity, but the mean orientation bandwidth of the SC was broader than that of V1 cells (101.5° vs. 60.2°). The mean optimal spatial frequency (SF) of SC cells was lower but had a broader bandwidth than that of V1 cells (0.03 vs. 0.068 cpd). The majority of SC and V1 cells (70% and 68%, respectively) had RFs with band-pass temporal frequency (TF) tuning profiles and similar optimal TFs. However, temporal band-pass profiles of the SC showed narrower mean temporal bandwidths than those of V1 cells (1.42 vs. 2.36 octaves). The majority of neurons in visual cortical and subcortical structures were activated in response to high-contrast, drifting gratings in the preferred orientation. The percentage of V1 neurons with a low-contrast threshold was larger than the proportion of SC neurons (45.6% vs. 30%), indicating that the former adapt better to contrast. The substantial overlap in latency distributions between SC and V1 areas suggests that the two visual systems process and analyze visual signals in parallel. However, the two areas use different neural encoding mechanisms based on different latency distribution trends. These results indicate that SC cells have poor spatial acuity

  10. Spatial selectivity and binaural responses in the inferior colliculus of the great horned owl.

    PubMed

    Volman, S F; Konishi, M

    1989-09-01

    In this study we have investigated the processing of auditory cues for sound localization in the great horned owl (Bubo virginianus). Previous studies have shown that the barn owl, whose ears are asymmetrically oriented in the vertical plane, has a 2-dimensional, topographic representation of auditory space in the external division of the inferior colliculus (ICx). As in the barn owl, the great horned owl's ICx is anatomically distinct and projects to the optic tectum. Neurons in ICx respond over only a small range of azimuths (mean = 32 degrees), and azimuth is topographically mapped. In contrast to the barn owl, the great horned owl has bilaterally symmetrical ears and its receptive fields are not restricted in elevation. The binaural cues available for sound localization were measured both with cochlear microphonic recordings and with a microphone attached to a probe tube in the auditory canal. Interaural time disparity (ITD) varied monotonically with azimuth. Interaural intensity differences (IID) also changed with azimuth, but the largest IIDs were less than 15 dB, and the variation was not monotonic. Neither ITD nor IID varied systematically with changes in the vertical position of a sound source. We used dichotic stimulation to determine the sensitivity of ICx neurons to these binaural cues. Best ITD of ICx units was topographically mapped and strongly correlated with receptive-field azimuth. The width of ITD tuning curves, measured at 50% of the maximum response, averaged 72 microseconds. All ICx neurons responded only to binaural stimulation and had nonmonotonic IID tuning curves. Best IID was weakly, but significantly, correlated with best ITD (r = 0.39, p less than 0.05). The IID tuning curves, however, were broad (mean 50% width = 24 dB), and 67% of the units had best IIDs within 5 dB of 0 dB IID. ITD tuning was sensitive to variations in IID in the direction opposite to that expected for time-intensity trading, but the magnitude of this effect was only

  11. Active diffusion positions the nucleus in mouse oocytes.

    PubMed

    Almonacid, Maria; Ahmed, Wylie W; Bussonnier, Matthias; Mailly, Philippe; Betz, Timo; Voituriez, Raphaël; Gov, Nir S; Verlhac, Marie-Hélène

    2015-04-01

    In somatic cells, the position of the cell centroid is dictated by the centrosome. The centrosome is instrumental in nucleus positioning, the two structures being physically connected. Mouse oocytes have no centrosomes, yet harbour centrally located nuclei. We demonstrate how oocytes define their geometric centre in the absence of centrosomes. Using live imaging of oocytes, knockout for the formin 2 actin nucleator, with off-centred nuclei, together with optical trapping and modelling, we discover an unprecedented mode of nucleus positioning. We document how active diffusion of actin-coated vesicles, driven by myosin Vb, generates a pressure gradient and a propulsion force sufficient to move the oocyte nucleus. It promotes fluidization of the cytoplasm, contributing to nucleus directional movement towards the centre. Our results highlight the potential of active diffusion, a prominent source of intracellular transport, able to move large organelles such as nuclei, providing in vivo evidence of its biological function. PMID:25774831

  12. Astrocytic Connexin Distributions and Rapid, Extensive Dye Transfer Via Gap Junctions in the Inferior Colliculus: Implications for [14C]Glucose Metabolite Trafficking

    PubMed Central

    Ball, Kelly K.; Gandhi, Gautam K.; Thrash, Jarrod; Cruz, Nancy F.; Dienel, Gerald A.

    2010-01-01

    The inferior colliculus has the highest rates of blood flow and metabolism in brain, and functional metabolic activity increases markedly in response to acoustic stimulation. However, brain imaging with [1- and 6-14C]glucose greatly underestimates focal metabolic activation that is readily detected with [14C]deoxyglucose, suggesting that labeled glucose metabolites are quickly dispersed and released from highly activated zones of the inferior colliculus. To evaluate the role of coupling of astrocytes via gap junctions in dispersal of molecules within the inferior colliculus, the present study assessed the distribution of connexin (Cx) proteins in the inferior colliculus and spreading of Lucifer yellow from single microinjected astrocytes in slices of adult rat brain. Immunoreactive Cx43, Cx30, and Cx26 were heterogeneously distributed; the patterns for Cx43 and Cx 30 differed and were similar to those of immunoreactive GFAP and S100β, respectively. Most Cx43 was phosphorylated in resting and acoustically stimulated rats. Dye spreading revealed an extensive syncytial network that included thousands of cells and perivasculature endfeet; with 8% Lucifer yellow VS and a 5-min diffusion duration, about 6,100 astrocytes (range 2,068–11,939) were labeled as far as 1–1.5 mm from the injected cell. The relative concentration of Lucifer yellow fell by 50% within 0.3–0.8 mm from the injected cell with a 5-min diffusion interval. Perivascular dye labeling was readily detectable and often exceeded dye levels in nearby neuropil. Thus, astrocytes have the capability to distribute intracellular molecules quickly from activated regions throughout the large, heterogeneous syncytial volume of the inferior colliculus, and rapid trafficking of labeled metabolites would degrade resolution of focal metabolic activation. PMID:17600824

  13. Antiproton-nucleus interaction

    NASA Astrophysics Data System (ADS)

    Cugnon, J.; Vandermeulen, J.

    The antiproton-nucleus physics is reviewed. On the experimental side, the recent results obtained at the LEAR, BNL and KEK facilities are analyzed. A brief summary of the main pp and pn experimental data is also given. The antiproton-nucleus interaction can lead to elasic, inelastic and charge exchange scattering and to annihilation. The latter is very dominant. The scattering cross-sections are usually analyzed in terms of complex potential models. The relationship between potentials, charge conjugation and Dirac phenomenology is discussed. Much emphasis is put on the dynamics of the antiproton annihilation on nuclei. The energy transfer, pion absorption and target response are analyzed within the intranuclear cascade model. Special interest is devoted to strangeness production, hypernucleus formation and possible annihilation on two nucleons. Signatures for this new process are searched in experimental data. Finally, the highly debated question of quark-gluon formation is analyzed. Cet article constitue une revue de la physique antiproton-noyau. Du point de vue expérimental, cette revue porte particulièrement sur les récents résultats obtenus à LEAR, BNL et KEK. On y a aussi inclus une mise à jour des faits expérimentaux principaux pour pp et pn. L'interaction antiproton-noyau conduit à la diffusion élastique, inélastique et d'xA9change de charge et à des processus d'annihilation. Habituellement, les expériences de diffusion sont analysées en termes de potentiels complexes. La relation entre ces potentiels, la conjugaison de charge et la phénoménologie de Dirac est discutée. On s'est particulièrement intéressé à la dynamique de l'annihilation d'antiprotons sur des noyaux. Le transfert d'énergie, l'absorption de pions et la réponse de la cible sont analysés dans le cadre du modèle de cascade intranucléaire. Certains autres points sont discutés plus en détail: la production d'étrangeté, la formation d'hypernoyaux et l'annihilation sur

  14. Revisiting the supratrigeminal nucleus in the rat.

    PubMed

    Fujio, T; Sato, F; Tachibana, Y; Kato, T; Tomita, A; Higashiyama, K; Ono, T; Maeda, Y; Yoshida, A

    2016-06-01

    The supratrigeminal nucleus (Vsup), originally proposed as a premotoneuron pool in the trigeminal reflex arc, is a key structure of jaw movement control. Surprisingly, however, the location of the rat Vsup has not precisely been defined. In light of our previous cat studies, we made two hypotheses regarding the rat Vsup: (1) the Vsup is cytoarchitectonically distinguishable from its surrounding structures; (2) the Vsup receives central axon terminals of the trigeminal mesencephalic nucleus (Vmes) neurons which are primary afferents innervating muscle spindles of jaw-closing muscles and periodontal ligaments around the teeth. To test the first hypothesis, we examined the cytoarchitecture of the rat Vsup. The Vsup was identified as an area medially adjacent to the dorsomedial part of trigeminal principal sensory nucleus (Vp), and extended from the level just rostral to the caudal two-thirds of the trigeminal motor nucleus (Vmo) to the level approximately 150μm caudal to the Vmo. Our rat Vsup was much smaller and its location was considerably different in comparison to the Vsup reported previously. To evaluate the second hypothesis, we tested the distribution patterns of Vmes primary afferent terminals in the cytoarchitectonically identified Vsup. After transganglionic tracer applications to the masseter, deep temporal, and medial pterygoid nerves, a large number of axon terminals were observed in all parts of Vsup (especially in its medial part). After applications to the inferior alveolar, infraorbital, and lingual nerves, a small number of axon terminals were labeled in the caudolateral Vsup. The Vsup could also be identified electrophysiologically. After electrical stimulation of the masseter nerve, evoked potentials with slow negative component were isolated only in the Vsup. The present findings suggest that the rat Vsup can be cytoarchitectonically and electrophysiologically identified, receives somatotopic termination of the trigeminal primary afferents, and

  15. Mechanics of the Nucleus

    PubMed Central

    Lammerding, Jan

    2015-01-01

    The nucleus is the distinguishing feature of eukaryotic cells. Until recently, it was often considered simply as a unique compartment containing the genetic information of the cell and associated machinery, without much attention to its structure and mechanical properties. This article provides compelling examples that illustrate how specific nuclear structures are associated with important cellular functions, and how defects in nuclear mechanics can cause a multitude of human diseases. During differentiation, embryonic stem cells modify their nuclear envelope composition and chromatin structure, resulting in stiffer nuclei that reflect decreased transcriptional plasticity. In contrast, neutrophils have evolved characteristic lobulated nuclei that increase their physical plasticity, enabling passage through narrow tissue spaces in their response to inflammation. Research on diverse cell types further demonstrates how induced nuclear deformations during cellular compression or stretch can modulate cellular function. Pathological examples of disturbed nuclear mechanics include the many diseases caused by mutations in the nuclear envelope proteins lamin A/C and associated proteins, as well as cancer cells that are often characterized by abnormal nuclear morphology. In this article, we will focus on determining the functional relationship between nuclear mechanics and cellular (dys-)function, describing the molecular changes associated with physiological and pathological examples, the resulting defects in nuclear mechanics, and the effects on cellular function. New insights into the close relationship between nuclear mechanics and cellular organization and function will yield a better understanding of normal biology and will offer new clues into therapeutic approaches to the various diseases associated with defective nuclear mechanics. PMID:23737203

  16. Central organization of eighth nerve and mechanosensory lateral line systems in the brainstem of ictalurid catfish.

    PubMed

    Finger, T E; Tong, S L

    1984-10-10

    The octavolateral sensory systems in teleost fish comprise at least four distinct hair-cell sensory modalities which are processed separately within the CNS. Two of these modalities, the mechanosensory lateral line system and the eighth nerve auditory system, have been implicated in the animal's ability to detect and localize underwater vibrations. Distinct mechanosensory lateral line and auditory nuclei are present within the torus semicircularis, the midbrain homologue of the inferior colliculus. The present study utilized horseradish peroxidase tracing techniques to delineate those areas of the lower brainstem which are involved in auditory as opposed to mechanosensory lateral line processes. The primary mechanosensory nucleus of the medulla, n. medialis, projects directly to the optic tectum and to the mechanosensory nucleus of the torus semicircularis. Nucleus medialis receives input from primary lateral line nerve fibers as well as from a number of sites within the CNS: n. praeeminentialis pars ventralis, and the eminentia granularis and lobus caudalis of the cerebellum. The n. praeeminentialis itself receives a descending input from the mechanosensory nucleus of the torus semicircularis. These mechanosensory lateral line pathways are parallel to, but distinct from, those of the electrosensory lateral line system. Auditory signals reach the midbrain via an entirely separate route. The octaval nerve terminates in a column of five medullary nuclei. Of these, only the anterior and descending octaval nuclei maintain a direct but sparse projection to the auditory nucleus of the midbrain. The bulk of the auditory input to the midbrain involves a newly described medullary nucleus, the medial auditory nucleus of the medulla. This nucleus receives input from the descending octaval nucleus and projects bilaterally to the auditory nucleus of the torus semicircularis. It is suggested that the medial auditory nucleus of the medulla is homologous to portions of the

  17. Retrotrapezoid nucleus, respiratory chemosensitivity and breathing automaticity

    PubMed Central

    Guyenet, Patrice G.; Bayliss, Douglas A.; Stornetta, Ruth L.; Fortuna, Michal G.; Abbott, Stephen B.; Depuy, Seth D.

    2009-01-01

    SUMMARY Breathing automaticity and CO2 regulation are inseparable neural processes. The retrotrapezoid nucleus (RTN), a group of glutamatergic neurons that express the transcription factor Phox2b, may be a crucial nodal point through which breathing automaticity is regulated to maintain CO2 constant. This review updates the analysis presented in prior publications. Additional evidence that RTN neurons have central respiratory chemoreceptor properties is presented but this is only one of many factors that determine their activity. The RTN is also regulated by powerful inputs from the carotid bodies and, at least in the adult, by many other synaptic inputs. We also analyze how RTN neurons may control the activity of the downstream central respiratory pattern generator. Specifically, we review the evidence which suggests that RTN neurons a) innervate the entire ventral respiratory column, and b) control both inspiration and expiration. Finally, we argue that the RTN neurons are the adult form of the parafacial respiratory group in neonate rats. PMID:19712903

  18. Two Neutron Removal in Relativistic Nucleus-Nucleus Reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for double neutron removal via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work examines the cause of these discrepancies and systematically investigates whether the problem might be due to electromagnetic theory, nuclear contributions, or an underestimate of experimental error. Using cross section systematics from other reactions it is found that the discrepancies can be resolved in a plausible manner.

  19. Effects of location and timing of co-activated neurons in the auditory midbrain on cortical activity: implications for a new central auditory prosthesis

    NASA Astrophysics Data System (ADS)

    Straka, Małgorzata M.; McMahon, Melissa; Markovitz, Craig D.; Lim, Hubert H.

    2014-08-01

    Objective. An increasing number of deaf individuals are being implanted with central auditory prostheses, but their performance has generally been poorer than for cochlear implant users. The goal of this study is to investigate stimulation strategies for improving hearing performance with a new auditory midbrain implant (AMI). Previous studies have shown that repeated electrical stimulation of a single site in each isofrequency lamina of the central nucleus of the inferior colliculus (ICC) causes strong suppressive effects in elicited responses within the primary auditory cortex (A1). Here we investigate if improved cortical activity can be achieved by co-activating neurons with different timing and locations across an ICC lamina and if this cortical activity varies across A1. Approach. We electrically stimulated two sites at different locations across an isofrequency ICC lamina using varying delays in ketamine-anesthetized guinea pigs. We recorded and analyzed spike activity and local field potentials across different layers and locations of A1. Results. Co-activating two sites within an isofrequency lamina with short inter-pulse intervals (<5 ms) could elicit cortical activity that is enhanced beyond a linear summation of activity elicited by the individual sites. A significantly greater extent of normalized cortical activity was observed for stimulation of the rostral-lateral region of an ICC lamina compared to the caudal-medial region. We did not identify any location trends across A1, but the most cortical enhancement was observed in supragranular layers, suggesting further integration of the stimuli through the cortical layers. Significance. The topographic organization identified by this study provides further evidence for the presence of functional zones across an ICC lamina with locations consistent with those identified by previous studies. Clinically, these results suggest that co-activating different neural populations in the rostral-lateral ICC rather

  20. Dynamical and Statistical Aspects in Nucleus--Nucleus Collisions Around the Fermi Energy

    NASA Astrophysics Data System (ADS)

    Tamain, B.; Assenard, M.; Auger, G.; Bacri, C. O.; Benlliure, J.; Bisquer, E.; Bocage, F.; Borderie, B.; Bougault, R.; Buchet, P.; Charvet, J. L.; Chbihi, A.; Colin, J.; Cussol, D.; Dayras, R.; Demeyer, A.; Dore, D.; Durand, D.; Eudes, P.; Frankland, J.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Germain, M.; Gourio, D.; Guinet, D.; Gulminelli, F.; Lautesse, P.; Laville, J. L.; Lebrun, C.; Lecolley, J. F.; Lefevre, A.; Lefort, T.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Lukasik, J.; Marie, N.; Maskay, M.; Metivier, V.; Nalpas, L.; Nguyen, A.; Parlog, M.; Peter, J.; Plagnol, E.; Rahmani, A.; Reposeur, T.; Rivet, M. F.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Squalli, M.; Steckmeyer, J. C.; Stern, M.; Tabacaru, T.; Tassan-Got, L.; Tirel, O.; Vient, E.; Volan, C.; Wieleczko, J. P.

    1998-01-01

    This contribution is devoted to two important aspects of intermediate energy nucleus-nucleus collisions: the competition of dynamical and statistical features, and the origin of the multifragmentation process. These two questions are discussed in focusing on Indra data. It turns out that most of collisions are binary and reminiscent of deep inelastic collisions observed at low energy. However, intermediate velocity emission is a clear signature of dynamical emission and establishes a link with the participant-spectator picture which applies at high bombarding energies. Multifragmentation is observed when the dissipated energy is large and it turns out that expansion occurs at least for central collisions, as it is expected if this phenomenum has a dynamical origin.

  1. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  2. Sensitivity of cross sections for elastic nucleus-nucleus scattering to halo nucleus density distributions

    SciTech Connect

    Alkhazov, G. D.; Sarantsev, V. V.

    2012-12-15

    In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.

  3. Afferent connections of the parabrachial nucleus in C57BL/6J mice

    PubMed Central

    Tokita, Kenichi; Inoue, Tomio; Boughter, John D.

    2009-01-01

    Although the mouse is an experimental model with an increasing importance in various fields of Neuroscience, the characteristics of its central gustatory pathways have not yet been well documented. Recent electrophysiological studies using the rat and hamster have revealed that taste processing in the brainstem gustatory relays is under the strong influence of inputs from forebrain gustatory structures. In the present study, we investigated the organization of afferent projections to the mouse parabrachial nucleus (PbN), which is located at a key site between the brainstem and gustatory, viscerosensory and autonomic centers in the forebrain. We made injections of the retrograde tracer Fluorogold centered around the “waist” area of the PbN, whose neurons are known to be highly responsive to taste stimuli. Retrogradely labeled neurons were found in the infralimbic, dysgranular and agranular insular cortex as well as the claustrum; the bed nucleus of the stria terminalis and the substantia innominata; the central nucleus of the amygdala; the lateral and medial preoptic areas, the paraventricular, the dorsomedial, the ventromedial, the arcuate, and the lateral hypothalamic areas; the periaqueductal gray, the substantia nigra pars compacta, and the ventral tegmental area; the supratrigeminal nucleus, rostral and caudal nucleus of the solitary tract; the parvicellular intermediate and gigantocellular reticular nucleus; the caudal and interpolar divisions of the spinal trigeminal nucleus, dorsomedial spinal trigeminal nucleus, and the area postrema. Numbers of labeled neurons in the main components of the gustatory system including the insular cortex, bed nucleus of the stria terminalis, central nucleus of the amygdala, lateral hypothalamus, and rostral nucleus of the solitary tract were quantified. These results are basically consistent with those of the previous rat and hamster studies, but some species differences were found. Functional implications of these

  4. Hadron multiplicities and chemical freeze-out conditions in proton-proton and nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Vovchenko, V.; Begun, V. V.; Gorenstein, M. I.

    2016-06-01

    New results of the NA61/SHINE Collaboration at the CERN SPS on mean hadron multiplicities in proton-proton (p+p) interactions are analyzed within the transport models and the hadron resonance gas (HRG) statistical model. The chemical freeze-out parameters in p+p interactions and central Pb+Pb (or Au+Au) collisions are found and compared with each other in the range of the center-of-mass energy of the nucleon pair √{sN N}=3.2 -17.3 GeV. The canonical ensemble formulation of the HRG model is used to describe mean hadron multiplicities in p+p interactions and the grand canonical ensemble in central Pb+Pb and Au+Au collisions. The chemical freeze-out temperatures in p+p interactions are found to be larger than the corresponding temperatures in central nucleus-nucleus collisions.

  5. Double Nucleus in M83

    NASA Astrophysics Data System (ADS)

    Mast, Damián; Díaz, Rubén J.; Agüero, M. Paz

    2006-03-01

    M83 is one of the nearest galaxies with enhanced nuclear star formation, and it presents one of the best opportunities to study the kinematics and physical properties of a circumnuclear starburst. Our three-dimensional spectroscopy data in the R band confirm the presence of a secondary nucleus or mass concentration (previously suggested by Thatte and coworkers). We determine the position of this hidden nucleus, which would be more massive than the visible one and was not detected in the optical Hubble Space Telescope images due, probably, to the strong dust extinction. Using a Keplerian approximation, we estimated for the optical nucleus a mass of (5.0+/-0.8)×106 Msolar/sini (r<1.5"), and for the hidden nucleus, located 4''+/-1'' to the northwest (position angle of 271deg+/-15deg) of the optical nucleus, a mass of (1.00+/-0.08)×107 Msolar/sini (r<1.5"). The emission-line ratio map also unveils the presence of a second circumnuclear ring structure, previously discovered by IR imaging (Elmegreen and coworkers). The data allow us to resolve the behavior of the interstellar medium inside the circumnuclear ring and around the binary mass concentration.

  6. Central collisions of heavy ions

    SciTech Connect

    Fung, Sun-yiu.

    1992-10-01

    This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1991 to September 30, 1992. During this period, the program focused on particle production at AGS energies, and correlation studies at the Bevalac in nucleus-nucleus central collisions. As part of the PHENIX collaboration, contributions were made to the Preliminary Conceptual Design Report (pCDR), and work on a RHIC silicon microstrip detector R D project was performed.

  7. Connections of the Superior Paraolivary Nucleus of the Rat: II. Reciprocal Connections with the Tectal Longitudinal Column

    PubMed Central

    Viñuela, Antonio; Aparicio, M.-Auxiliadora; Berrebi, Albert S.; Saldaña, Enrique

    2010-01-01

    The superior paraolivary nucleus (SPON), a prominent GABAergic center of the mammalian auditory brainstem, projects to the ipsilateral inferior colliculus (IC) and sends axons through the commissure of the IC (CoIC). Herein we demonstrate that the SPON is reciprocally connected with the recently discovered tectal longitudinal column (TLC). The TLC is a long and narrow structure that spans nearly the entire midbrain tectum longitudinally, immediately above the periaqueductal gray matter (PAG) and very close to the midline. Unilateral injections of biotinylated dextran into the SPON of the rat label abundant terminal fibers in the TLC of both sides, with an ipsilateral predominance. The SPON provides a dense innervation of the entire rostrocaudal extent of the ipsilateral TLC, and a relatively sparser innervation of the caudal and rostral portions of the contralateral TLC. SPON fibers reach the TLC by two routes: as collaterals of axons of the CoIC, and as axons that circumvent the ipsilateral IC before traveling in the deep layers of the superior colliculus (SC). The density of these projections identifies SPON as a significant source of input to the TLC. Other targets of the SPON discovered in this study include the deep layers of the SC and the PAG. The same experiments reveal numerous labeled cell bodies in the TLC, interspersed among the labeled SPON fibers. This observation suggests that the SPON is a significant target of TLC projections. The discovery of novel reciprocal connections between the SPON and the TLC opens unexpected avenues for investigation of sound processing in mammalian brainstem circuits. PMID:21373368

  8. Independent feedback control of horizontal and vertical amplitude during oblique saccades evoked by electrical stimulation of the superior colliculus.

    PubMed

    Nichols, M J; Sparks, D L

    1996-12-01

    1. In early local feedback models for controlling horizontal saccade amplitude, a feedback signal of instantaneous eye position is continuously subtracted from a reference signal of desired eye position at a comparator. The output of the comparator is dynamic motor error, the remaining distance the eyes must rotate to reach the saccadic goal. When feedback reduces dynamic motor error to zero, the saccade stops on target. Two classes of local feedback model have been proposed for controlling oblique saccades (i.e., saccades with both horizontal and vertical components). In "independent comparator" models, separate horizontal and vertical comparators maintain independent representations of horizontal and vertical dynamic motor error. Thus, once an oblique desired displacement signal is established, the horizontal and vertical amplitudes of oblique saccades are under independent feedback control. In "vectorial comparator" models, output cells in the motor map of the superior colliculus act as site-specific vectorial comparators. For a given oblique desired displacement, a single comparator controls the amplitudes of both components. Because vectorial comparator models do not maintain separate representations of horizontal and vertical dynamic motor error, they cannot exert independent control over the component amplitudes of oblique saccades. 2. We tested differential predictions of these two types of models by electrically stimulating sites in the superior colliculus of rhesus monkey immediately after either vertical or horizontal visually guided saccades. We have shown previously that, despite the fixed site of collicular stimulation, the amplitude of the visually guided saccades systematically alters the amplitude of the corresponding component (horizontal or vertical) of stimulation-evoked saccades. However, in the present study, we examined the effect of the visually guided saccades on the amplitude of the orthogonal component of stimulation-evoked saccades. 3

  9. Nucleus management with irrigating vectis.

    PubMed

    Srinivasan, Aravind

    2009-01-01

    The main objective in modern cataract surgery is to achieve a better unaided visual acuity with rapid post-surgical recovery and minimal surgery-related complications. Early visual rehabilitation and better unaided vision can be achieved only by reducing the incision size. In manual small incision cataract surgery (MSICS), incision is between 5.5 to 7 mm. Once the nucleus is prolapsed into the anterior chamber, it can be extracted through the tunnel. Nucleus extraction with an irrigating vectis is a very simple technique, which combines mechanical and hydrostatic forces to express out the nucleus. This technique is time-tested with good results and more than 95% of nuclei in MSICS are extracted in this way offering all the merits of phacoemulsification with the added benefits of having wider applicability, better safety, shorter learning curve and lower cost. PMID:19075403

  10. [The role of the nucleus accumbens in psychiatric disorders].

    PubMed

    Mavridis, I

    2015-01-01

    The nucleus accumbens is the most inferior part of the striatum and is mainly connected to the limbic system. It is neurochemically and immunohistochemically divided into a shell laterally and a core medially. As a functionally central structure between amygdala, basal ganglia, mesolimbic dopaminergic regions, mediodorsal thalamus and prefrontal cortex, the nucleus accumbens appears to play a modulative role in the flow of the information from the amygdaloid complex to these regions. Dopamine is a major neurotransmitter of the nucleus accumbens and this nucleus has a modulative function to the amygdala-basal ganglia-prefrontal cortex circuit. Together with the prefrontal cortex and amygdala, nucleus accumbens consists a part of the cerebral circuit which regulates functions associated with effort. It is anatomically located in a unique way to serve emotional and behavioral components of feelings. It is considered as a neural interface between motivation and action, having a key-role in food intake, sexual behavior, reward-motivated behavior, stress-related behavior and substance-dependence. It is involved in several cognitive, emotional and psychomotor functions, altered in some psychopathology. Moreover it is involved in some of the commonest and most severe psychiatric disorders, such as depression, schizophrenia, obsessive-compulsive disorder and other anxiety disorders, as well as in addiction, including drugs abuse, alcoholism and smoking. Nucleus accumbens has also a role in other psychiatric disorders such as bipolar disorder, attention deficit/ hyperactivity disorder and post-traumatic stress disorder. Because of its rich dopaminergic projections, this nucleus has been subject of many studies in animals as well as in humans, connecting its malfunction with the disturbed reward process observed in depression. Neuromodulation interventions targeting the nucleus accumbens are nowadays applied in strictly selected patients suffering from treatment

  11. Cometary nucleus and active regions

    NASA Technical Reports Server (NTRS)

    Whipple, F. L.

    1984-01-01

    On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

  12. Formin' actin in the nucleus.

    PubMed

    Baarlink, Christian; Grosse, Robert

    2014-01-01

    Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner. PMID:24637338

  13. Acridine: a versatile heterocyclic nucleus.

    PubMed

    Kumar, Ramesh; Kaur, Mandeep; Kumari, Meena

    2012-01-01

    Acridine is a heterocyclic nucleus. It plays an important role in various medicines. A number of therapeutic agents are based on acridine nucleus such as quinacrine (antimalarial), acriflavine and proflavine (antiseptics), ethacridine (abortifacient), amsacrine and nitracine (anticancer), and tacrine. Acridine is obtained from high boiling fraction of coal tar. It is also obtained in nature from plant and marine sources. Acridine undergoes a number of reactions such as nucleophilic addition, electrophilic substitution, oxidation, reduction, reductive alkylation and photoalkylation. The present review article summarizes the synthesis, reaction, literature review and pharmaceutical importance of acridine. PMID:22574501

  14. Deep Brain Stimulation of the Pedunculopontine Tegmental Nucleus (PPN) Influences Visual Contrast Sensitivity in Human Observers

    PubMed Central

    Strumpf, Hendrik; Noesselt, Toemme; Schoenfeld, Mircea Ariel; Voges, Jürgen; Panther, Patricia; Kaufmann, Joern; Heinze, Hans-Jochen; Hopf, Jens-Max

    2016-01-01

    The parapontine nucleus of the thalamus (PPN) is a neuromodulatory midbrain structure with widespread connectivity to cortical and subcortical motor structures, as well as the spinal cord. The PPN also projects to the thalamus, including visual relay nuclei like the LGN and the pulvinar. Moreover, there is intense connectivity with sensory structures of the tegmentum in particular with the superior colliculus (SC). Given the existence and abundance of projections to visual sensory structures, it is likely that activity in the PPN has some modulatory influence on visual sensory selection. Here we address this possibility by measuring the visual discrimination performance (luminance contrast thresholds) in a group of patients with Parkinson’s Disease (PD) treated with deep-brain stimulation (DBS) of the PPN to control gait and postural motor deficits. In each patient we measured the luminance-contrast threshold of being able to discriminate an orientation-target (Gabor-grating) as a function of stimulation frequency (high 60Hz, low 8/10, no stimulation). Thresholds were determined using a standard staircase-protocol that is based on parameter estimation by sequential testing (PEST). We observed that under low frequency stimulation thresholds increased relative to no and high frequency stimulation in five out of six patients, suggesting that DBS of the PPN has a frequency-dependent impact on visual selection processes at a rather elementary perceptual level. PMID:27167979

  15. Temporal properties of responses to sound in the ventral nucleus of the lateral lemniscus

    PubMed Central

    Joris, Philip X.

    2013-01-01

    Besides the rapid fluctuations in pressure that constitute the “fine structure” of a sound stimulus, slower fluctuations in the sound's envelope represent an important temporal feature. At various stages in the auditory system, neurons exhibit tuning to envelope frequency and have been described as modulation filters. We examine such tuning in the ventral nucleus of the lateral lemniscus (VNLL) of the pentobarbital-anesthetized cat. The VNLL is a large but poorly accessible auditory structure that provides a massive inhibitory input to the inferior colliculus. We test whether envelope filtering effectively applies to the envelope spectrum when multiple envelope components are simultaneously present. We find two broad classes of response with often complementary properties. The firing rate of onset neurons is tuned to a band of modulation frequencies, over which they also synchronize strongly to the envelope waveform. Although most sustained neurons show little firing rate dependence on modulation frequency, some of them are weakly tuned. The latter neurons are usually band-pass or low-pass tuned in synchronization, and a reverse-correlation approach demonstrates that their modulation tuning is preserved to nonperiodic, noisy envelope modulations of a tonal carrier. Modulation tuning to this type of stimulus is weaker for onset neurons. In response to broadband noise, sustained and onset neurons tend to filter out envelope components over a frequency range consistent with their modulation tuning to periodically modulated tones. The results support a role for VNLL in providing temporal reference signals to the auditory midbrain. PMID:24285864

  16. Stimulation with chronically implanted microelectrodes in the cochlear nucleus of the cat: histologic and physiologic effects.

    PubMed

    McCreery, D B; Yuen, T G; Agnew, W F; Bullara, L A

    1992-09-01

    The effects of several hours of continuous electrical stimulation in the cats' cochlear nucleus with chronically implanted activated iridium microelectrodes was investigated from the changes in the evoked response near the inferior colliculus and also by histologic evaluation of the stimulated tissue. The stimulating microelectrodes had geometric surface areas of 75-500 microns2. They were pulsed continuously for 4 h, at a pulse repetition rate of 200 Hz, using charge-balanced pulse pairs. The charge per phase was 1.8 or 3.6 nC/ph. The animals were sacrificed for histologic evaluation 2 h, or several days later. The only remarkable histologic change resulting from the 4 h of stimulation was some aggregation of lymphocytes at the site of stimulation. However, depression of the electrical excitability of neurons near the sites often persisted for several days after 4 h of stimulation at 3.6 nC/phase. The charge per phase of the stimulus pulse pair was correlated strongly with the depression of excitability, and there was a weaker correlation between the depression and the amplitude of the first phase of voltage transient induced across the electrode-tissue interface. The charge density, calculated from the geometric surface area of the stimulating electrodes, was poorly correlated with the severity of the depression. The findings suggest a means of detecting impending stimulation-induced neural damage while it is still reversible. PMID:1429250

  17. Stimulus parameters affecting tissue injury during microstimulation in the cochlear nucleus of the cat.

    PubMed

    McCreery, D B; Yuen, T G; Agnew, W F; Bullara, L A

    1994-06-15

    We investigated the effects of continuous microstimulation in the cats' posteroventral cochlear nucleus, using chronically implanted activated iridium microelectrodes. We examined 51 electrode sites (39 pulsed sites, and 12 unpulsed sites). Seven hours of continuous stimulation at 500 Hz often produced tissue injury near the tips of the pulsed microelectrodes. The damage took the form of a region of vacuolated tissue extending 200 microns or more from the site of the electrode tip. Electron microscope studies showed the vacuoles to be severely edematous segments of myelinated axons. The statistical correlation between the amount of damaged tissue and the charge per phase was large and highly significant (P < 0.0001). When the electrodes were pulsed for 7 h at 500 Hz with charge-balanced biphasic pulse pairs, the threshold for the damage was approximately 3 nC/phase. The damage threshold was not appreciably lower than the stimulation protocol was extended to 35 h (7 h/day for 5 days). In contrast, the threshold for exciting neurons near the microelectrode is approximately 1 nC/phase, as determined by the evoked response recorded in the inferior colliculus. There was little correlation between the severity of the tissue damage and the geometric charge density at the surface of the electrodes, between the damage and amplitude of the cathodic phase of the voltage transient induced across the stimulating electrodes by the stimulus current pulses, or between the damage and the stimulus pulse duration. PMID:7928722

  18. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  19. EOS: A time projection chamber for the study of nucleus-nucleus collisions at the Bevalac

    SciTech Connect

    Pugh, H.G.; Odyniec, G.; Rai, G.; Seidl, P.

    1986-12-01

    The conceptual design is presented for a detector to identify and measure (..delta..p/p approx. = 1%) most of the 200 or so mid-rapidity charged particles (p, d, t, /sup 3/He, /sup 4/He, ..pi../sup + -/, K/sup + -/) produced in each central nucleus-nucleus collision (Au + Au) at Bevalac energies, as well as K/sub 3//sup 0/ and ..lambda../sup 0/. The beam particles and heavy spectator fragments are excluded from the detection volume by means of a central vacuum pipe. Particle identification is achieved by a combination of dE/dx measurements in the TPC, and of time-of-flight measurements in a scintillator array. The TPC is single-ended and its end cap is entirely covered with cathode pads (about 25,000 pads and about 1000 anode wires). A non-uniform pad distribution is proposed to accommodate the high multiplicity of particles emitted at forward angles. The performance of the detector is assessed with regard to multihit capability, tracking, momentum resolution, particle identification, ..lambda../sup 0/ reconstruction, space charge effects, field non-uniformity, dynamic range, data acquisition rate, and data analysis rate. 72 refs., 48 figs., 11 tabs.

  20. Inhibitory Plasticity Facilitates Recovery of Stimulus Velocity Tuning in the Superior Colliculus after Chronic NMDA Receptor Blockade

    PubMed Central

    Razak, Khaleel A.; Pallas, Sarah L.

    2016-01-01

    The developing nervous system is shaped in important ways by spontaneous and stimulus-driven neural activity. Perturbation of normal activity patterns can profoundly affect the development of some neural response properties, whereas others are preserved through mechanisms that either compensate for or are unaffected by the perturbation. Most studies have examined the role of excitation in activity-dependent plasticity of response properties. Here, we examine the role of inhibition within the context of response selectivity for moving stimuli. The spatial extent of retinal input to the developing hamster superior colliculus (SC) can be experimentally increased by chronic NMDA receptor (NMDAR) blockade. Remarkably, stimulus velocity tuning is intact despite the increase in excitatory inputs. The goal of this study was to investigate whether plasticity in surround inhibition might provide the mechanism underlying this preservation of velocity tuning. Surround inhibition shapes velocity tuning in the majority of superficial layer SC neurons in normal hamsters. We show that despite the NMDAR blockade-induced increase in feedforward excitatory convergence from the retina, stimulus velocity tuning in the SC is maintained via compensatory plasticity in surround inhibition. The inhibitory surround increased in strength and spatial extent, and surround inhibition made a larger contribution to velocity tuning in the SC after chronic NMDAR blockade. These results show that inhibitory plasticity can preserve the balance between excitation and inhibition that is necessary to preserve response properties after developmental manipulations of neural activity. Understanding these compensatory mechanisms may permit their use to facilitate recovery from trauma or sensory deprivation. PMID:17611280

  1. Target representation of naturalistic echolocation sequences in single unit responses from the inferior colliculus of big brown bats

    NASA Astrophysics Data System (ADS)

    Sanderson, Mark I.; Simmons, James A.

    2005-11-01

    Echolocating big brown bats (Eptesicus fuscus) emit trains of frequency-modulated (FM) biosonar signals whose duration, repetition rate, and sweep structure change systematically during interception of prey. When stimulated with a 2.5-s sequence of 54 FM pulse-echo pairs that mimic sounds received during search, approach, and terminal stages of pursuit, single neurons (N=116) in the bat's inferior colliculus (IC) register the occurrence of a pulse or echo with an average of <1 spike/sound. Individual IC neurons typically respond to only a segment of the search or approach stage of pursuit, with fewer neurons persisting to respond in the terminal stage. Composite peristimulus-time-histogram plots of responses assembled across the whole recorded population of IC neurons depict the delay of echoes and, hence, the existence and distance of the simulated biosonar target, entirely as on-response latencies distributed across time. Correlated changes in pulse duration, repetition rate, and pulse or echo amplitude do modulate the strength of responses (probability of the single spike actually occurring for each sound), but registration of the target itself remains confined exclusively to the latencies of single spikes across cells. Modeling of echo processing in FM biosonar should emphasize spike-time algorithms to explain the content of biosonar images.

  2. Response Normalization in the Superficial Layers of the Superior Colliculus as a Possible Mechanism for Saccadic Averaging

    PubMed Central

    Vokoun, Corinne R.; Huang, Xin; Jackson, Meyer B.

    2014-01-01

    How does the brain decide where to look? Neuronal networks within the superior colliculus (SC) encode locations of intended eye movements. When faced with multiple targets, the relative activities of neuronal populations compete for the selection of a saccade. However, the computational principles underlying saccadic choices remain poorly understood. We used voltage imaging of slices of rat SC to record circuit dynamics of population responses to single- and dual-site electrical stimulation to begin to reveal some of the principles of how populations of neurons interact. Stimulation of two distant sites simultaneously within the SC produced two distinct peaks of activity, whereas stimulation of two nearby sites simultaneously exhibited a single, merged peak centered between the two sites. The distances required to produce merged peaks of activity corresponded to target separations that evoked averaging saccades in humans performing a corresponding dual target task. The merged activity was well accounted for by a linear weighed summation and a divisive normalization of the responses evoked by the single-site stimulations. Interestingly, the merging of activity occurred within the superficial SC, suggesting a novel pathway for saccadic eye movement choice. PMID:24899719

  3. Neurons in the Most Superficial Lamina of the Mouse Superior Colliculus Are Highly Selective for Stimulus Direction

    PubMed Central

    Inayat, Samsoon; Barchini, Jad; Chen, Hui; Feng, Liang; Liu, Xiaorong

    2015-01-01

    The superior colliculus (SC) is a layered midbrain structure important for multimodal integration and sensorimotor transformation. Its superficial layers are purely visual and receive depth-specific projections from distinct subtypes of retinal ganglion cells. Here we use two-photon calcium imaging to characterize the response properties of neurons in the most superficial lamina of the mouse SC, an undersampled population with electrophysiology. We find that these neurons have compact receptive fields with primarily overlapping ON and OFF subregions and are highly direction selective. The high selectivity is observed in both excitatory and inhibitory neurons. These neurons do not cluster according to their direction preference and lack orientation selectivity. In addition, we perform single-unit recordings and show that direction selectivity declines with depth in the SC. Together, our experiments reveal for the first time a highly specialized lamina in the most superficial SC for movement direction, a finding that has important implications for understanding signal transformation in the early visual system. PMID:25995482

  4. Connectivity between the superior colliculus and the amygdala in humans and macaque monkeys: virtual dissection with probabilistic DTI tractography

    PubMed Central

    Koller, Kristin; Bultitude, Janet H.; Mullins, Paul; Ward, Robert; Mitchell, Anna S.; Bell, Andrew H.

    2015-01-01

    It has been suggested that some cortically blind patients can process the emotional valence of visual stimuli via a fast, subcortical pathway from the superior colliculus (SC) that reaches the amygdala via the pulvinar. We provide in vivo evidence for connectivity between the SC and the amygdala via the pulvinar in both humans and rhesus macaques. Probabilistic diffusion tensor imaging tractography revealed a streamlined path that passes dorsolaterally through the pulvinar before arcing rostrally to traverse above the temporal horn of the lateral ventricle and connect to the lateral amygdala. To obviate artifactual connectivity with crossing fibers of the stria terminalis, the stria was also dissected. The putative streamline between the SC and amygdala traverses above the temporal horn dorsal to the stria terminalis and is positioned medial to it in humans and lateral to it in monkeys. The topography of the streamline was examined in relation to lesion anatomy in five patients who had previously participated in behavioral experiments studying the processing of emotionally valenced visual stimuli. The pulvinar lesion interrupted the streamline in two patients who had exhibited contralesional processing deficits and spared the streamline in three patients who had no deficit. Although not definitive, this evidence supports the existence of a subcortical pathway linking the SC with the amygdala in primates. It also provides a necessary bridge between behavioral data obtained in future studies of neurological patients, and any forthcoming evidence from more invasive techniques, such as anatomical tracing studies and electrophysiological investigations only possible in nonhuman species. PMID:26224780

  5. Neurons in the inferior colliculus of the rat show stimulus-specific adaptation for frequency, but not for intensity

    PubMed Central

    Duque, Daniel; Wang, Xin; Nieto-Diego, Javier; Krumbholz, Katrin; Malmierca, Manuel S.

    2016-01-01

    Electrophysiological and psychophysical responses to a low-intensity probe sound tend to be suppressed by a preceding high-intensity adaptor sound. Nevertheless, rare low-intensity deviant sounds presented among frequent high-intensity standard sounds in an intensity oddball paradigm can elicit an electroencephalographic mismatch negativity (MMN) response. This has been taken to suggest that the MMN is a correlate of true change or “deviance” detection. A key question is where in the ascending auditory pathway true deviance sensitivity first emerges. Here, we addressed this question by measuring low-intensity deviant responses from single units in the inferior colliculus (IC) of anesthetized rats. If the IC exhibits true deviance sensitivity to intensity, IC neurons should show enhanced responses to low-intensity deviant sounds presented among high-intensity standards. Contrary to this prediction, deviant responses were only enhanced when the standards and deviants differed in frequency. The results could be explained with a model assuming that IC neurons integrate over multiple frequency-tuned channels and that adaptation occurs within each channel independently. We used an adaptation paradigm with multiple repeated adaptors to measure the tuning widths of these adaption channels in relation to the neurons’ overall tuning widths. PMID:27066835

  6. Cortex contacts both output neurons and nitrergic interneurons in the superior colliculus: Direct and Indirect routes for multisensory integration

    PubMed Central

    Fuentes-Santamaria, Veronica; Alvarado, Juan Carlos; Stein, Barry E.; McHaffie, John G.

    2010-01-01

    The ability of cat superior colliculus (SC) neurons to integrate information from different senses is thought to depend on direct projections from regions along the anterior ectosylvian sulcus (AES). However, electrical stimulation of AES also activates SC output neurons polysynaptically. In the present study we found that nitric oxide containing (nitrergic) interneurons are a target of AES projections, forming a component of this cortico-SC circuitry. The dendritic and axonal processes of these cortico-recipient nitrergic interneurons apposed the soma and dendrites of presumptive SC output neurons. Often, an individual cortical fiber targeted both an output neuron and a neighboring nitrergic interneuron that, in turn, contacted the output neuron. Many (46%) nitrergic neurons also colocalized with γ-aminobutyric acid (GABA), suggesting that a substantial subset have the potential for inhibiting output neurons. These observations suggest that nitrergic interneurons are positioned to convey cortical influences onto SC output neurons disynaptically via nitrergic mechanisms as well as conventional neurotransmitter systems utilizing GABA and other, possibly excitatory, neurotransmitters. In addition, because NO also acts as a retrograde messenger, cortically-mediated NO release from the post-synaptic elements of nitrergic interneurons could influence presynaptic cortico-SC terminals that directly contact output neurons. PMID:18003596

  7. Dichotic sound localization properties of duration-tuned neurons in the inferior colliculus of the big brown bat

    PubMed Central

    Sayegh, Riziq; Aubie, Brandon; Faure, Paul A.

    2014-01-01

    Electrophysiological studies on duration-tuned neurons (DTNs) from the mammalian auditory midbrain have typically evoked spiking responses from these cells using monaural or free-field acoustic stimulation focused on the contralateral ear, with fewer studies devoted to examining the electrophysiological properties of duration tuning using binaural stimulation. Because the inferior colliculus (IC) receives convergent inputs from lower brainstem auditory nuclei that process sounds from each ear, many midbrain neurons have responses shaped by binaural interactions and are selective to binaural cues important for sound localization. In this study, we used dichotic stimulation to vary interaural level difference (ILD) and interaural time difference (ITD) acoustic cues and explore the binaural interactions and response properties of DTNs and non-DTNs from the IC of the big brown bat (Eptesicus fuscus). Our results reveal that both DTNs and non-DTNs can have responses selective to binaural stimulation, with a majority of IC neurons showing some type of ILD selectivity, fewer cells showing ITD selectivity, and a number of neurons showing both ILD and ITD selectivity. This study provides the first demonstration that the temporally selective responses of DTNs from the vertebrate auditory midbrain can be selective to binaural cues used for sound localization in addition to having spiking responses that are selective for stimulus frequency, amplitude, and duration. PMID:24959149

  8. Maturation of multisensory integration in the superior colliculus: Expression of nitric oxide synthase and neurofilament SMI-32

    PubMed Central

    Fuentes-Santamaria, Veronica; McHaffie, John G.; Stein, Barry E.

    2010-01-01

    Nitric oxide (NO) containing (nitrergic) interneurons are well-positioned to convey the cortical influences that are crucial for multisensory integration in superior colliculus (SC) output neurons. However, it is not known whether nitrergic interneurons are in this position early in life, and might, therefore, also play a role in the functional maturation of this circuit. In the present study, we investigated the postnatal developmental relationship between these two populations of neurons using B-nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH) histochemistry and SMI-32 immunocytochemistry to label presumptive interneurons and output neurons, respectively. SMI-32 immunostained neurons were proved to mature and retained immature anatomical features until approximately 8 postnatal weeks. In contrast, nitrergic interneurons developed more rapidly. They had achieved their adult-like anatomy by 4 postnatal weeks and were in a position to influence the dendritic elaboration of output neurons. It is this dendritic substrate through which much of the cortico-collicular influence is expressed. Double-labeling experiments showed that the dendritic and axonal processes of nitrergic interneurons already apposed the somata and dendrites of SMI-32 labeled neurons even at the earliest age examined. The results suggest that nitrergic interneurons play a role in refining the cortico-collicular projection patterns that are believed to be essential for SC output neurons to engage in multisensory integration and to support normal orientation responses to cross-modal stimuli. PMID:18486108

  9. Higgs and Particle Production in Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Liu, Zhe

    We apply a diagrammatic approach to study Higgs boson, a color-neutral heavy particle, pro- duction in nucleus-nucleus collisions in the saturation framework without quantum evolution. We assume the strong coupling constant much smaller than one. Due to the heavy mass and colorless nature of Higgs particle, final state interactions are absent in our calculation. In order to treat the two nuclei dynamically symmetric, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. To further eliminate initial state interactions we choose specific prescriptions in the light cone propagators. We start the calculation from only two nucleons in each nucleus and then demonstrate how to generalize the calculation to higher orders diagrammatically. We simplify the diagrams by the Slavnov-Taylor-Ward identities. The resulting cross section is factorized into a product of two Weizsacker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. To our knowledge this is the first process where an exact analytic formula has been formed for a physical process, involving momenta on the order of the saturation momentum, in nucleus-nucleus collisions in the quasi-classical approximation. Since we have performed the calculation in an unconventional gauge choice, we further confirm our results in Feynman gauge where the Weizsacker-Williams gluon distribution is interpreted as a transverse momentum broadening of a hard gluons traversing a nuclear medium. The transverse momentum factorization manifests itself in light cone gauge but not so clearly in Feynman gauge. In saturation physics there are two different unintegrated gluon distributions usually encountered in the literature: the Weizsacker-Williams gluon distribution and the dipole gluon distribution. The first gluon distribution is constructed by solving classical Yang-Mills equation of motion in the Mc

  10. Dynamical nucleus-nucleus potential at short distances

    SciTech Connect

    Jiang Yongying; Wang Ning; Li Zhuxia; Scheid, Werner

    2010-04-15

    The dynamical nucleus-nucleus potentials for fusion reactions {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 208}Pb, and {sup 126}Sn+{sup 130}Te are studied with the improved quantum molecular dynamics model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for {sup 40}Ca+{sup 40}Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depths of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of the fusion barrier is also investigated. The fusion pocket becomes shallow for a heavy fusion system and almost disappears for heavy nearly symmetric systems, and the obtained potential at short distances is higher than the adiabatic potential.

  11. Azimuthal correlation and collective behavior in nucleus-nucleus collisions

    SciTech Connect

    Mali, P.; Mukhopadhyay, A. Sarkar, S.; Singh, G.

    2015-03-15

    Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from {sup 84}Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from {sup 28}Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.

  12. Analysis of relativistic nucleus-nucleus interactions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1987-01-01

    The development of a computer-assisted method is reported for the determination of the angular distribution data for secondary particles produced in relativistic nucleus-nucleus collisions in emulsions. The method is applied to emulsion detectors that were placed in a constant, uniform magnetic field and exposed to beams of 60 and 200 GeV/nucleon O-16 ions at the Super Proton Synchrotron (SPS) of the European Center for Nuclear Research (CERN). Linear regression analysis is used to determine the azimuthal and polar emission angles from measured track coordinate data. The software, written in BASIC, is designed to be machine independent, and adaptable to an automated system for acquiring the track coordinates. The fitting algorithm is deterministic, and takes into account the experimental uncertainty in the measured points. Further, a procedure for using the track data to estimate the linear momenta of the charged particles observed in the detectors is included.

  13. Single nucleon emission in relativistic nucleus-nucleus reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors.

  14. Hummingbird Comet Nucleus Analysis Mission

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

    2000-01-01

    Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

  15. Effects of the blockade of opioid receptor on defensive reactions elicited by electrical stimulation within the deep layers of the superior colliculus and DPAG.

    PubMed

    Coimbra, N C; Eichenberger, G C; Gorchinski, R T; Maisonnette, S

    1996-10-14

    The effects of peripheral administration of naloxone and naltrexone on aversive thresholds (freezing and escape reactions) elicited by electrical stimulation of the midbrain tectum were determined. Naloxone caused a significant increase in the freezing and flight thresholds elicited by electrical stimulation in the deep layers of the superior colliculus and of dorsal regions of the periaqueductal grey matter, as compared with controls. These effects were confirmed by the peripheral administration of naltrexone. These findings suggest that opioid receptors can modulate aversive behaviour elicited by midbrain tectum stimulation. PMID:8930342

  16. Visual experience prevents dysregulation of GABAB receptor-dependent short-term depression in adult superior colliculus

    PubMed Central

    Balmer, Timothy S.

    2015-01-01

    Progressive loss of plasticity during development prevents refined circuits from regressing to an immature state and is thought to depend on maturation of GABAergic inhibition. For example, a gradual reduction in size of visual receptive fields (RFs) occurs in the superior colliculus (SC) during development. Maintenance of the refined state throughout adulthood requires early light exposure. Here we investigate the potential role of changes in long- or short-term plasticity in experience-dependent maintenance of refined RFs. Using an acute SC slice preparation, we found that long-term plasticity was not affected by visual deprivation, indicating that it does not underlie deprivation-induced RF enlargement. In contrast, visual deprivation altered short-term plasticity in an unexpected way. Specifically, GABAB receptor (GABABR)-mediated paired pulse depression was increased in slices from dark-reared animals. This increase was mimicked by GABAAR blockade in slices from normally reared animals, suggesting that experience-dependent maintenance of GABAAR function prevents an increase in probability of neurotransmitter release. GABABR-mediated short-term depression in response to strong stimulation (such as occurs during vision) was reduced in slices from dark-reared animals. This change was mimicked in slices from normal animals by reducing GABA release. These results are consistent with the hypothesis that early visual experience maintains GABAergic inhibition and prevents later deprivation-induced alterations of short-term depression in SC. Identifying how plasticity is restricted in mature circuits could guide therapies to enhance recovery of function in adults. PMID:25568162

  17. Dual sensitivity of inferior colliculus neurons to ITD in the envelopes of high-frequency sounds: experimental and modeling study

    PubMed Central

    Wang, Le; Devore, Sasha; Delgutte, Bertrand

    2013-01-01

    Human listeners are sensitive to interaural time differences (ITDs) in the envelopes of sounds, which can serve as a cue for sound localization. Many high-frequency neurons in the mammalian inferior colliculus (IC) are sensitive to envelope-ITDs of sinusoidally amplitude-modulated (SAM) sounds. Typically, envelope-ITD-sensitive IC neurons exhibit either peak-type sensitivity, discharging maximally at the same delay across frequencies, or trough-type sensitivity, discharging minimally at the same delay across frequencies, consistent with responses observed at the primary site of binaural interaction in the medial and lateral superior olives (MSO and LSO), respectively. However, some high-frequency IC neurons exhibit dual types of envelope-ITD sensitivity in their responses to SAM tones, that is, they exhibit peak-type sensitivity at some modulation frequencies and trough-type sensitivity at other frequencies. Here we show that high-frequency IC neurons in the unanesthetized rabbit can also exhibit dual types of envelope-ITD sensitivity in their responses to SAM noise. Such complex responses to SAM stimuli could be achieved by convergent inputs from MSO and LSO onto single IC neurons. We test this hypothesis by implementing a physiologically explicit, computational model of the binaural pathway. Specifically, we examined envelope-ITD sensitivity of a simple model IC neuron that receives convergent inputs from MSO and LSO model neurons. We show that dual envelope-ITD sensitivity emerges in the IC when convergent MSO and LSO inputs are differentially tuned for modulation frequency. PMID:24155013

  18. Presynaptic group I metabotropic glutamate receptors modulate synaptic transmission in the rat superior colliculus via 4-AP sensitive K+ channels

    PubMed Central

    White, Anne-Marie; Kylänpää, Risto A; Christie, Louisa A; McIntosh, Simon J; Irving, Andrew J; Platt, Bettina

    2003-01-01

    Group I metabotropic glutamate receptors (mGluRs) are thought to be important modulators of neuronal function in the superior colliculus (SC). Here, we investigated the pharmacology and signalling mechanisms underlying group I mGluR-mediated inhibition of neuronal excitability and synaptic transmission in the rat SC slice. The group I agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) potently depressed synaptically evoked excitatory postsynaptic potentials (EPSPs), currents (EPSCs), and action potentials in a dose-dependent manner (IC50: 6.3 μM). This was strongly reduced by the broad-spectrum antagonist (+)-alpha-methyl-4-carboxyphenylglycine (MCPG, 1 mM, ∼95% reduction), by the mGluR1 antagonist LY367385 (100 μM, ∼80% reduction) but not by the mGluR5 antagonist 6-methyl-2-(phenylethynyl)-pyridine (MPEP, 1–100 μM). The putative mGluR5-specific agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG, 500 μM) also inhibited EPSPs. Interestingly, CHPG's actions were not blocked by MPEP, but LY367385 (100 μM) reduced the effect of CHPG by 50%. Inhibition induced by DHPG was independent of phospholipase C (PLC)/protein kinase C pathways, and did not require intact intracellular Ca2+ stores. It was not abolished but enhanced by the GABAA antagonist bicuculline (5 μM), suggesting that DHPG's action was not due to facilitated inhibition or changes in neuronal network activity. The K+ channel antagonist 4-aminopyridine (4-AP, 50–100 μM) converted the inhibitory effect of DHPG into facilitation. Paired-pulse depression was strongly reduced by DHPG, an effect that was also prevented by 4-AP. Our data indicate that group I agonists regulate transmitter release, presumably via an autoreceptor in the SC. This receptor may be involved in adaptation to repetitive stimulation via a non-PLC mediated pathway. PMID:14623765

  19. The three-dimensional frequency organization of the inferior colliculus of the cat: a 2-deoxyglucose study.

    PubMed

    Brown, M; Webster, W R; Martin, R L

    1997-02-01

    The 3-dimensional (3-D) functional organization of the cat's inferior colliculus (IC) was examined using the 2-deoxyglucose method. Animals were dichotically stimulated with pure tone stimuli at an intensity of 80 dB SPL. Autoradiographic sections from these animals, cut in the three standard planes, were serially reconstructed to reveal the 3-D topography of the isofrequency sheets of labelling. In all 3-D reconstructions, the isofrequency sheets extend rostrocaudally through the IC with the rostral aspect of the sheet being situated more ventral than its caudal aspect. In the mediolateral dimensions, sheets are angled at between 40 degrees and 60 degrees to the horizontal, running from a dorsomedial to a ventrolateral position. The low-frequency sheets (0.5 and 2 kHz) are dorsolaterally convex and situated in the dorsolateral region of the IC. The 4 and 10 kHz isofrequency sheets have a helical structure and are situated in the mid-region of the IC. The high-frequency sheets (20 and 30 kHz) are dorsolaterally concaved and situated in the ventromedial region of the IC. The topography of these isofrequency sheets generally agree with, and extended our knowledge of, the tonotopic organization of the IC as derived from electrophysiological studies. The functional organization revealed by the 2-deoxyglucose method only partially correlated with the neural laminae in the anatomical models of the IC proposed by Rockel and Jones [J. Comp. Neurol. 147 (1973) 11-60] and Oliver and Morest [J. Comp. Neurol. 222 (1984) 237-264]. It is therefore concluded that the neural laminar organization of the IC may not be a necessary substrate for the tonotopic organization seen the IC. PMID:9119767

  20. Physiological role of group III metabotropic glutamate receptors in visually responsive neurons of the rat superficial superior colliculus.

    PubMed

    Cirone, J; Salt, T E

    2000-03-01

    There is evidence from immunohistochemical and in situ hybridization studies for the presence of Group I, II and III metabotropic glutamate receptors (mGluRs) in the rat superficial superior colliculus (SSC). The purpose of this study was to investigate if manipulation of Group III mGluRs affects visual responses in the SSC. Drugs were applied by iontophoresis and single neuron activity was recorded extracellularly. L-AP4 (Group III agonist) resulted in a reduction of visual responses in most neurons, but also a potentiation in others. The effect of L-AP4 is drug- and stereospecific in that application of D-AP4 did not significantly affect visual responses. L-AP4 application also resulted in a potentiation of the response to iontophoretically applied NMDA. The effects of MPPG and CPPG (Group III antagonists) were compared with the effect of L-AP4 in the same neuron and were found to produce the opposite effect to L-AP4. Furthermore, the effect of L-AP4 could be blocked by coapplication of MPPG or CPPG. Presynaptic depression of glutamate release is a possible mechanism by which L-AP4 could reduce visual responses in the SSC whereas the potentiation of visual responses by L-AP4 could be due to a reduction of GABAergic inhibition. The finding that MPPG and CPPG, as well as antagonizing the L-AP4 effect, have a direct effect on visual responses suggests that Group III mGluRs are activated by endogenous transmitter released during visual stimulation. PMID:10762314

  1. Group II and III metabotropic glutamate receptors contribute to different aspects of visual response processing in the rat superior colliculus

    PubMed Central

    Cirone, Jennifer; Salt, Thomas E

    2001-01-01

    Neurones in the superior colliculus (SC) respond to novel sensory stimuli and response habituation is a key feature of this. It is known that both ionotropic and metabotropic glutamate (mGlu) receptors participate in visual responses of superficial SC neurones. A feature of Group II and Group III mGlu receptors is that they may modulate specific neural pathways, possibly via presynaptic mechanisms. However, less is known about how this may relate to functions of systems in whole animals. We have therefore investigated whether these receptors affect specific attributes of visual responses in the superficial SC. Recordings were made from visually responsive neurones in anaesthetised rats, and agonists and antagonists of Group II and III mGlu receptors were applied iontophoretically at the recording site. We found that application of the Group III metabotropic glutamate receptor agonist l-2-amino-4-phosphonobutyric acid (l-AP4) produced an increase in visual response habituation, whilst Group III antagonists decreased habituation. These effects were independent of the response habituation mediated via GABAB receptors. In contrast, modulation of Group II mGlu receptors with the specific agonist LY354740 or the antagonist LY341495 did not affect response habituation, although these compounds did modulate visual responses. This suggests a specific role for Group III mGlu receptors in visual response habituation. The magnitude of Group II effects was smaller during presentation of low contrast stimuli compared with high contrast stimuli. This suggests that activation of Group II receptors may be activity dependent and that these receptors can translate this into a functional effect in adapting to high contrast stimuli. PMID:11433000

  2. Recovery cycle times of inferior colliculus neurons in the awake bat measured with spike counts and latencies

    PubMed Central

    Sayegh, Riziq; Aubie, Brandon; Fazel-Pour, Siavosh; Faure, Paul A.

    2012-01-01

    Neural responses in the mammalian auditory midbrain (inferior colliculus; IC) arise from complex interactions of synaptic excitation, inhibition, and intrinsic properties of the cell. Temporally selective duration-tuned neurons (DTNs) in the IC are hypothesized to arise through the convergence of excitatory and inhibitory synaptic inputs offset in time. Synaptic inhibition can be inferred from extracellular recordings by presenting pairs of pulses (paired tone stimulation) and comparing the evoked responses of the cell to each pulse. We obtained single unit recordings from the IC of the awake big brown bat (Eptesicus fuscus) and used paired tone stimulation to measure the recovery cycle times of DTNs and non-temporally selective auditory neurons. By systematically varying the interpulse interval (IPI) of the paired tone stimulus, we determined the minimum IPI required for a neuron's spike count or its spike latency (first- or last-spike latency) in response to the second tone to recover to within ≥50% of the cell's baseline count or to within 1 SD of it's baseline latency in response to the first tone. Recovery times of shortpass DTNs were significantly shorter than those of bandpass DTNs, and recovery times of bandpass DTNs were longer than allpass neurons not selective for stimulus duration. Recovery times measured with spike counts were positively correlated with those measured with spike latencies. Recovery times were also correlated with first-spike latency (FSL). These findings, combined with previous studies on duration tuning in the IC, suggest that persistent inhibition is a defining characteristic of DTNs. Herein, we discuss measuring recovery times of neurons with spike counts and latencies. We also highlight how persistent inhibition could determine neural recovery times and serve as a potential mechanism underlying the precedence effect in humans. Finally, we explore implications of recovery times for DTNs in the context of bat hearing and

  3. Spatiotemporal profiles of receptive fields of neurons in the lateral posterior nucleus of the cat LP-pulvinar complex.

    PubMed

    Piché, Marilyse; Thomas, Sébastien; Casanova, Christian

    2015-10-01

    The pulvinar is the largest extrageniculate thalamic visual nucleus in mammals. It establishes reciprocal connections with virtually all visual cortexes and likely plays a role in transthalamic cortico-cortical communication. In cats, the lateral posterior nucleus (LP) of the LP-pulvinar complex can be subdivided in two subregions, the lateral (LPl) and medial (LPm) parts, which receive a predominant input from the striate cortex and the superior colliculus, respectively. Here, we revisit the receptive field structure of LPl and LPm cells in anesthetized cats by determining their first-order spatiotemporal profiles through reverse correlation analysis following sparse noise stimulation. Our data reveal the existence of previously unidentified receptive field profiles in the LP nucleus both in space and time domains. While some cells responded to only one stimulus polarity, the majority of neurons had receptive fields comprised of bright and dark responsive subfields. For these neurons, dark subfields' size was larger than that of bright subfields. A variety of receptive field spatial organization types were identified, ranging from totally overlapped to segregated bright and dark subfields. In the time domain, a large spectrum of activity overlap was found, from cells with temporally coinciding subfield activity to neurons with distinct, time-dissociated subfield peak activity windows. We also found LP neurons with space-time inseparable receptive fields and neurons with multiple activity periods. Finally, a substantial degree of homology was found between LPl and LPm first-order receptive field spatiotemporal profiles, suggesting a high integration of cortical and subcortical inputs within the LP-pulvinar complex. PMID:26289469

  4. Photoproduction of lepton pairs in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies

    SciTech Connect

    Moreira, B. D.; Goncalves, V. P.; De Santana Amaral, J. T.

    2013-03-25

    In this contribution we study coherent interactions as a probe of the nonlinear effects in the Quantum Electrodynamics (QED). In particular, we study the multiphoton effects in the production of leptons pairs for proton-nucleus and nucleus-nucleus collisions for heavy nuclei. In the proton-nucleus we assume the ultrarelativistic proton as a source of photons and estimate the photoproduction of lepton pairs on nuclei at RHIC and LHC energies considering the multiphoton effects associated to multiple rescattering of the projectile photon on the proton of the nucleus. In nucleus - nucleus colllisions we consider the two nuclei as a source of photons. As each scattering contributes with a factor {alpha}Z to the cross section, this contribution must be taken into account for heavy nuclei. We consider the Coulomb corrections to calculate themultiple scatterings and estimate the total cross section for muon and tau pair production in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies.

  5. The ascending projection of the nucleus of the lateral descending trigeminal tract: a nucleus in the infrared system of the rattlesnake, Crotalus viridis

    SciTech Connect

    Stanford, L.R.; Schroeder, D.M.; Hartline, P.H.

    1981-01-01

    The efferent projections of the nucleus of the lateral descending trigeminal tract (LTTD) in the rattlesnake (Crotalus viridis) were studied by anterograde tracing techniques. The LTTD, a brainstem trigeminal nucleus, is the sole projection site of the infrared-sensitive trigeminal fibers that innervate the pit organs in these snakes. The efferent fibers exit from the ventromedial edge of the LTTD and course medially and caudally toward the central grey area of the medulla. Upon reaching the central region of the medulla these fibers turn and move laterally and rostrally, eventually forming a tract on the ventrolateral surface of the brainstem. Embedded in this tract and slightly overlapping the LTTD in the rostrocaudal axis, is a population of large (20-45 micrometer) multipolar neurons that forms the nucleus reticularis caloris. Heavy terminal and preterminal degeneration in this area indicates that many of the efferent fibers of the LTTD terminate in this nucleus. A small bundle of degenerating fibers turn dorsally from the ventrolateral tract and ascend to terminate in a nucleus associated with the cerebellum, the lateral tegmental nucleus. No projection was found to any other nuclei or areas in the brain. This study demonstrates that the infrared-sensitive snakes, along with developing peripheral specializations (the pit organs), have developed specialized nuclei to handle this additional sensory information. The direct projection from the LTTD to the nucleus reticularis caloris provides a pathway linking the infrared-sensitive neurons of the LTTD with neurons of the same modality in the optic tectum. The second LTTD projection, to the lateral tegmental nucleus, suggests a connection between the infrared system and the cerebellum in these animals.

  6. Effects of central opiate and serotoninergic structures on heart rhythm during acute myocardial ischemia.

    PubMed

    Prokop'eva, E V; Pivovarov, Y I

    2001-12-01

    Electrostimulation of the central gray matter in the sylvian aqueduct and nucleus raphe magnus produced an antiarrhythmic effect during acute myocardial ischemia. Stimulation and blockade of opiate receptors in the central amygdaloid nucleus and lateral hypothalamus with dalargin and naloxone induced the same effect. Destruction of the central gray matter in the sylvian aqueduct and nucleus raphe magnus decreased electrical stability of ischemic myocardium. PMID:12152875

  7. Molecular gas in the starburt nucleus of M82

    NASA Technical Reports Server (NTRS)

    Lo, K. Y.

    1987-01-01

    The 7" resolution CO observations of the central 1 kpc of M82 have resolved 2 components of molecular gas: (1) a high concentration in the central 700 pc x 200 pc, and (2) extended features that may be gas expelled from the central concentration. The central concentration of molecular gas falls in the same confines as the other tracers of recent star formation, and may be identified directly with the star burst region. The molecular gas in the star burst nucleus of M82 appears to be highly disturbed and has high kinetic temperature, likely consequences of the high density of young star clusters. Stellar winds and subsequent supernovae from the star clusters can effectively sweep up the interstellar medium. The spatial distribution and kinematics of the nuclear concentration of the molecular gas, as well as the 2 micron light distribution, suggest the presence of a stellar bar in M82. Comparisons of the M82 star burst nucleus to a sample of IR luminous galaxies suggest that star burst regions in general may have a higher gas temperature and much higher L sub IR/M sub H2 that the galactic disk, and that the L sub IR of the star burst regions may be essentially proportional to their area.

  8. The cellular mastermind(?) – Mechanotransduction and the nucleus

    PubMed Central

    Kaminski, Ashley; Fedorchak, Gregory R.; Lammerding, Jan

    2015-01-01

    Cells respond to mechanical stimulation by activation of specific signaling pathways and genes that allow the cell to adapt to its dynamic physical environment. How cells sense the various mechanical inputs and translate them into biochemical signals remains an area of active investigation. Recent reports suggest that the cell nucleus may be directly implicated in this cellular mechanotransduction process. In this chapter, we discuss how forces applied to the cell surface and cytoplasm induce changes in nuclear structure and organization, which could directly affect gene expression, while also highlighting the complex interplay between nuclear structural proteins and transcriptional regulators that may further modulate mechanotransduction signaling. Taken together, these findings paint a picture of the nucleus as a central hub in cellular mechanotransduction—both structurally and biochemically—with important implications in physiology and disease. PMID:25081618

  9. Structures and functions in the crowded nucleus: new biophysical insights

    NASA Astrophysics Data System (ADS)

    Hancock, Ronald

    2014-09-01

    Concepts and methods from the physical sciences have catalysed remarkable progress in understanding the cell nucleus in recent years. To share this excitement with physicists and encourage their interest in this field, this review offers an overview of how the physics which underlies structures and functions in the nucleus is becoming more clear thanks to methods which have been developed to simulate and study macromolecules, polymers, and colloids. The environment in the nucleus is very crowded with macromolecules, making entropic (depletion) forces major determinants of interactions. Simulation and experiments are consistent with their key role in forming membraneless compartments such as nucleoli, PML and Cajal bodies, and discrete "territories" for chromosomes. The chromosomes, giant linear polyelectrolyte polymers, exist in vivo in a state like a polymer melt. Looped conformations are predicted in crowded conditions, and have been confirmed experimentally and are central to the regulation of gene expression. Polymer theory has revealed how the chromosomes are so highly compacted in the nucleus, forming a "crumpled globule" with fractal properties which avoids knots and entanglements in DNA while allowing facile accessibility for its replication and transcription. Entropic repulsion between looped polymers can explain the confinement of each chromosome to a discrete region of the nucleus. Crowding and looping are predicted to facilitate finding the specific targets of factors which modulate activities of DNA. Simulation shows that entropic effects contribute to finding and repairing potentially lethal double-strand breaks in DNA by increasing the mobility of the broken ends, favouring their juxtaposition for repair. Signaling pathways are strongly influenced by crowding, which favours a processive mode of response (consecutive reactions without releasing substrates). This new information contributes to understanding the sometimes counter-intuitive consequences.

  10. Comet nucleus sample return mission

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

  11. Theoretical antideuteron-nucleus absorptive cross sections

    NASA Technical Reports Server (NTRS)

    Buck, W. W.; Norbury, J. W.; Townsend, L. W.; Wilson, J. W.

    1993-01-01

    Antideuteron-nucleus absorptive cross sections for intermediate to high energies are calculated using an ion-ion optical model. Good agreement with experiment (within 15 percent) is obtained in this same model for (bar p)-nucleus cross sections at laboratory energies up to 15 GeV. We describe a technique for estimating antinucleus-nucleus cross sections from NN data and suggest that further cosmic ray studies to search for antideuterons and other antinuclei be undertaken.

  12. Functional network inference of the suprachiasmatic nucleus.

    PubMed

    Abel, John H; Meeker, Kirsten; Granados-Fuentes, Daniel; St John, Peter C; Wang, Thomas J; Bales, Benjamin B; Doyle, Francis J; Herzog, Erik D; Petzold, Linda R

    2016-04-19

    In the mammalian suprachiasmatic nucleus (SCN), noisy cellular oscillators communicate within a neuronal network to generate precise system-wide circadian rhythms. Although the intracellular genetic oscillator and intercellular biochemical coupling mechanisms have been examined previously, the network topology driving synchronization of the SCN has not been elucidated. This network has been particularly challenging to probe, due to its oscillatory components and slow coupling timescale. In this work, we investigated the SCN network at a single-cell resolution through a chemically induced desynchronization. We then inferred functional connections in the SCN by applying the maximal information coefficient statistic to bioluminescence reporter data from individual neurons while they resynchronized their circadian cycling. Our results demonstrate that the functional network of circadian cells associated with resynchronization has small-world characteristics, with a node degree distribution that is exponential. We show that hubs of this small-world network are preferentially located in the central SCN, with sparsely connected shells surrounding these cores. Finally, we used two computational models of circadian neurons to validate our predictions of network structure. PMID:27044085

  13. Modulation of GABAergic inhibition in the rat superior colliculus by a presynaptic group II metabotropic glutamate receptor.

    PubMed

    Neale, S A; Salt, T E

    2006-12-01

    Previous work has indicated that metabotropic glutamate receptors (mGluRs) modulate visual responses of superior colliculus (SC) neurones in vivo in a variety of ways, in a manner that can be dependent upon visual stimulus properties. How this occurs remains unclear. In this study we aimed to determine how activation of mGluR2 and mGluR3 receptors (Group II) might modulate visual responses, by using field potential and whole-cell patch clamp recording techniques in rat SC slice. Stimulation within the superficial layers of the SC, in the presence of ionotropic glutamate receptor antagonists, evoked IPSCs that were blocked by bicuculline indicating that they are mediated via GABAA receptors. It is likely that these IPSCs were of heterogeneous origin as they showed substantial variation in paired-pulse behaviour. Nevertheless, activation of Group II mGluRs with the group-selective agonist LY354740 (300 nM, bath application) resulted in a reduction of these IPSCs (to 56% of control amplitude), and this was associated with a decrease in paired-pulse depression. At the same concentration, LY354740 did not reduce the EPSC or field-EPSP evoked by stimulation of the retinal input to the SC. The effects of LY354740 on IPSCs were not mimicked by the mGluR3-selective agonist N-acetyl-aspartyl-glutamate (NAAG, 200-500 microM). Stimulation of IPSCs with trains of impulses (10 at 20 Hz) in order to mimic natural activation patterns resulted in sequences of IPSCs that were reduced in amplitude towards the end of the stimulus train. Application of the Group II antagonist LY341495 (100 nM) under these conditions resulted in an increase in later IPSCs in a third of neurones tested. These findings indicate that mGluR2 (but not mGluR3) can selectively modulate GABAergic inhibition in SC, probably via a presynaptic mechanism. Furthermore, these receptors may be activated by synaptically released transmitter during patterns of activation similar to those seen during visual processing

  14. Elucidation of the anatomy of a satiety network: Focus on connectivity of the parabrachial nucleus in the adult rat.

    PubMed

    Zséli, Györgyi; Vida, Barbara; Martinez, Anais; Lechan, Ronald M; Khan, Arshad M; Fekete, Csaba

    2016-10-01

    We hypothesized that brain regions showing neuronal activation after refeeding comprise major nodes in a satiety network, and tested this hypothesis with two sets of experiments. Detailed c-Fos mapping comparing fasted and refed rats was performed to identify candidate nodes of the satiety network. In addition to well-known feeding-related brain regions such as the arcuate, dorsomedial, and paraventricular hypothalamic nuclei, lateral hypothalamic area, parabrachial nucleus (PB), nucleus of the solitary tract and central amygdalar nucleus, other refeeding activated regions were also identified, such as the parastrial and parasubthalamic nuclei. To begin to understand the connectivity of the satiety network, the interconnectivity of PB with other refeeding-activated neuronal groups was studied following administration of anterograde or retrograde tracers into the PB. After allowing for tracer transport time, the animals were fasted and then refed before sacrifice. Refeeding-activated neurons that project to the PB were found in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamic area; arcuate, paraventricular, and dorsomedial hypothalamic nuclei; lateral hypothalamic area; parasubthalamic nucleus; central amygdalar nucleus; area postrema; and nucleus of the solitary tract. Axons originating from the PB were observed to closely associate with refeeding-activated neurons in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamus; paraventricular, arcuate, and dorsomedial hypothalamic nuclei; lateral hypothalamic area; central amygdalar nucleus; parasubthalamic nucleus; ventral posterior thalamic nucleus; area postrema; and nucleus of the solitary tract. These data indicate that the PB has bidirectional connections with most refeeding-activated neuronal groups, suggesting that short-loop feedback circuits exist in this satiety network. J. Comp. Neurol. 524:2803-2827, 2016. © 2016 Wiley Periodicals, Inc. PMID:26918800

  15. Bilateral dorsal cochlear nucleus lesions prevent acoustic-trauma induced tinnitus in an animal model.

    PubMed

    Brozoski, Thomas Jeffrey; Wisner, Kurt W; Sybert, Lauren T; Bauer, Carol A

    2012-02-01

    Animal experiments suggest that chronic tinnitus ("ringing in the ears") may result from processes that overcompensate for lost afferent input. Abnormally elevated spontaneous neural activity has been found in the dorsal cochlear nucleus (DCN) of animals with psychophysical evidence of tinnitus. However, it has also been reported that DCN ablation fails to reduce established tinnitus. Since other auditory areas have been implicated in tinnitus, the role of the DCN is unresolved. The apparently conflicting electrophysiological and lesion data can be reconciled if the DCN serves as a necessary trigger zone rather than a chronic generator of tinnitus. The present experiment used lesion procedures identical to those that failed to decrease pre-existing tinnitus. The exception was that lesions were done prior to tinnitus induction. Young adult rats were trained and tested using a psychophysical procedure shown to detect tinnitus. Tinnitus was induced by a single unilateral high-level noise exposure. Consistent with the trigger hypothesis, bilateral dorsal DCN lesions made before high-level noise exposure prevented the development of tinnitus. A protective effect stemming from disruption of the afferent pathway could not explain the outcome because unilateral lesions ipsilateral to the noise exposure did not prevent tinnitus and unilateral lesions contralateral to the noise exposure actually exacerbated the tinnitus. The DCN trigger mechanism may involve plastic circuits that, through loss of inhibition, or upregulation of excitation, increase spontaneous neural output to rostral areas such as the inferior colliculus. The increased drive could produce persistent pathological changes in the rostral areas, such as high-frequency bursting and decreased interspike variance, that comprise the chronic tinnitus signal. PMID:21969021

  16. Sodium Salicylate Suppresses GABAergic Inhibitory Activity in Neurons of Rodent Dorsal Raphe Nucleus

    PubMed Central

    Jin, Yan; Luo, Bin; Su, Yan-Yan; Wang, Xin-Xing; Chen, Liang; Wang, Ming; Wang, Wei-Wen; Chen, Lin

    2015-01-01

    Sodium salicylate (NaSal), a tinnitus inducing agent, can activate serotonergic (5-HTergic) neurons in the dorsal raphe nucleus (DRN) and can increase serotonin (5-HT) level in the inferior colliculus and the auditory cortex in rodents. To explore the underlying neural mechanisms, we first examined effects of NaSal on neuronal intrinsic properties and the inhibitory synaptic transmissions in DRN slices of rats by using whole-cell patch-clamp technique. We found that NaSal hyperpolarized the resting membrane potential, decreased the input resistance, and suppressed spontaneous and current-evoked firing in GABAergic neurons, but not in 5-HTergic neurons. In addition, NaSal reduced GABAergic spontaneous and miniature inhibitory postsynaptic currents in 5-HTergic neurons. We next examined whether the observed depression of GABAergic activity would cause an increase in the excitability of 5-HTergic neurons using optogenetic technique in DRN slices of the transgenic mouse with channelrhodopsin-2 expressed in GABAergic neurons. When the GABAergic inhibition was enhanced by optical stimulation to GABAergic neurons in mouse DRN, NaSal significantly depolarized the resting membrane potential, increased the input resistance and increased current-evoked firing of 5-HTergic neurons. However, NaSal would fail to increase the excitability of 5-HTergic neurons when the GABAergic synaptic transmission was blocked by picrotoxin, a GABA receptor antagonist. Our results indicate that NaSal suppresses the GABAergic activities to raise the excitability of local 5-HTergic neural circuits in the DRN, which may contribute to the elevated 5-HT level by NaSal in the brain. PMID:25962147

  17. Actomyosin contractility rotates the cell nucleus

    PubMed Central

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G. V.

    2014-01-01

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells. PMID:24445418

  18. Neuronal Correlates of Fear Conditioning in the Bed Nucleus of the Stria Terminalis

    ERIC Educational Resources Information Center

    Haufler, Darrell; Nagy, Frank Z.; Pare, Denis

    2013-01-01

    Lesion and inactivation studies indicate that the central amygdala (CeA) participates in the expression of cued and contextual fear, whereas the bed nucleus of the stria terminalis (BNST) is only involved in the latter. The basis for this functional dissociation is unclear because CeA and BNST form similar connections with the amygdala and…

  19. Heavy quark production by a quasi-classical color field in proton-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Tuchin, Kirill

    2004-07-01

    We calculate the inclusive heavy quark production cross section for proton-nucleus collisions at high energies. We perform calculation in a quasi-classical approximation (McLerran-Venugopalan model) neglecting all low-x evolution effects. The derived expression for the differential cross section can be applied for studying the heavy quark production in the central rapidity region at RHIC.

  20. The multifunctional lateral geniculate nucleus.

    PubMed

    Weyand, Theodore G

    2016-02-01

    Providing the critical link between the retina and visual cortex, the well-studied lateral geniculate nucleus (LGN) has stood out as a structure in search of a function exceeding the mundane 'relay'. For many mammals, it is structurally impressive: Exquisite lamination, sophisticated microcircuits, and blending of multiple inputs suggest some fundamental transform. This impression is bolstered by the fact that numerically, the retina accounts for a small fraction of its input. Despite such promise, the extent to which an LGN neuron separates itself from its retinal brethren has proven difficult to appreciate. Here, I argue that whereas retinogeniculate coupling is strong, what occurs in the LGN is judicious pruning of a retinal drive by nonretinal inputs. These nonretinal inputs reshape a receptive field that under the right conditions departs significantly from its retinal drive, even if transiently. I first review design features of the LGN and follow with evidence for 10 putative functions. Only two of these tend to surface in textbooks: parsing retinal axons by eye and functional group and gating by state. Among the remaining putative functions, implementation of the principle of graceful degradation and temporal decorrelation are at least as interesting but much less promoted. The retina solves formidable problems imposed by physics to yield multiple efficient and sensitive representations of the world. The LGN applies context, increasing content, and gates several of these representations. Even if the basic concentric receptive field remains, information transmitted for each LGN spike relative to each retinal spike is measurably increased. PMID:26479339

  1. Music and the nucleus accumbens.

    PubMed

    Mavridis, Ioannis N

    2015-03-01

    Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA. PMID:25102783

  2. Smallest Black Hole in Galactic Nucleus Detected

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    A team of astronomers have reported the detection of the smallest black hole (BH) ever observed in a galactic nucleus. The BH is hosted in the center of dwarf galaxy RGG 118, and it weighs in at 50,000 solar masses, according to observations made by Vivienne Baldassare of University of Michigan and her collaborators. Small Discoveries: Why is the discovery of a small nuclear BH important? Some open questions that this could help answer are: - Do the very smallest dwarf galaxies have BHs at their centers too? Though we believe that there's a giant BH at the center of every galaxy, we aren't sure how far down the size scale this holds true. - What is the formation mechanism for BHs at the center of galaxies? - What's the behavior of the M-sigma relation at the low-mass end? The M-sigma relation is an observed correlation between the mass of a galaxy's central BH and the velocity dispersion of the stars in the galaxy. This relation is incredibly useful for determining properties of distant BHs and their galaxies empirically, but little data is available to constrain the low-mass end of the relation. M-sigma relation, plotting systems with dynamically-measured black hole masses. RGG 118 is plotted as the pink star. The solid and dashed lines represent various determinations of scaling relations. Credit: Baldassare et al. 2015. Identifying a Black Hole: RGG 118 was identified as a candidate host for an accreting, nuclear BH from the catalog of dwarf galaxies observed in the Sloan Digital Sky Survey. Baldassare and her team followed up with high-resolution spectroscopy from the Clay telescope in Chile and Chandra x-ray observations. Using these observations, the team determined that RGG 118 plays host to a massive BH at its center based on three clues: 1) narrow emission line ratios, which is a signature of accretion onto a massive BH, 2) the presence of broad emission lines, indicating that gas is rotating around a central BH, and 3) the existence of an X-ray point

  3. Resonant Cholinergic Dynamics in Cognitive and Motor Decision-Making: Attention, Category Learning, and Choice in Neocortex, Superior Colliculus, and Optic Tectum

    PubMed Central

    Grossberg, Stephen; Palma, Jesse; Versace, Massimiliano

    2016-01-01

    Freely behaving organisms need to rapidly calibrate their perceptual, cognitive, and motor decisions based on continuously changing environmental conditions. These plastic changes include sharpening or broadening of cognitive and motor attention and learning to match the behavioral demands that are imposed by changing environmental statistics. This article proposes that a shared circuit design for such flexible decision-making is used in specific cognitive and motor circuits, and that both types of circuits use acetylcholine to modulate choice selectivity. Such task-sensitive control is proposed to control thalamocortical choice of the critical features that are cognitively attended and that are incorporated through learning into prototypes of visual recognition categories. A cholinergically-modulated process of vigilance control determines if a recognition category and its attended features are abstract (low vigilance) or concrete (high vigilance). Homologous neural mechanisms of cholinergic modulation are proposed to focus attention and learn a multimodal map within the deeper layers of superior colliculus. This map enables visual, auditory, and planned movement commands to compete for attention, leading to selection of a winning position that controls where the next saccadic eye movement will go. Such map learning may be viewed as a kind of attentive motor category learning. The article hereby explicates a link between attention, learning, and cholinergic modulation during decision making within both cognitive and motor systems. Homologs between the mammalian superior colliculus and the avian optic tectum lead to predictions about how multimodal map learning may occur in the mammalian and avian brain and how such learning may be modulated by acetycholine. PMID:26834535

  4. Interaural timing cues do not contribute to the map of space in the ferret superior colliculus: a virtual acoustic space study.

    PubMed

    Campbell, Robert A A; Doubell, Timothy P; Nodal, Fernando R; Schnupp, Jan W H; King, Andrew J

    2006-01-01

    In this study, we used individualized virtual acoustic space (VAS) stimuli to investigate the representation of auditory space in the superior colliculus (SC) of anesthetized ferrets. The VAS stimuli were generated by convolving broadband noise bursts with each animal's own head-related transfer function and presented over earphones. Comparison of the amplitude spectra of the free-field and VAS signals and of the spatial receptive fields of neurons recorded in the inferior colliculus with each form of stimulation confirmed that the VAS provided an accurate simulation of sounds presented in the free field. Units recorded in the deeper layers of the SC responded predominantly to virtual sound directions within the contralateral hemifield. In most cases, increasing the sound level resulted in stronger spike discharges and broader spatial receptive fields. However, the preferred sound directions, as defined by the direction of the centroid vector, remained largely unchanged across different levels and, as observed in previous free-field studies, varied topographically in azimuth along the rostrocaudal axis of the SC. We also examined the contribution of interaural time differences (ITDs) to map topography by digitally manipulating the VAS stimuli so that ITDs were held constant while allowing other spatial cues to vary naturally. The response properties of the majority of units, including centroid direction, remained unchanged with fixed ITDs, indicating that sensitivity to this cue is not responsible for tuning to different sound directions. These results are consistent with previous data suggesting that sensitivity to interaural level differences and spectral cues provides the basis for the map of auditory space in the mammalian SC. PMID:16162823

  5. Resonant Cholinergic Dynamics in Cognitive and Motor Decision-Making: Attention, Category Learning, and Choice in Neocortex, Superior Colliculus, and Optic Tectum.

    PubMed

    Grossberg, Stephen; Palma, Jesse; Versace, Massimiliano

    2015-01-01

    Freely behaving organisms need to rapidly calibrate their perceptual, cognitive, and motor decisions based on continuously changing environmental conditions. These plastic changes include sharpening or broadening of cognitive and motor attention and learning to match the behavioral demands that are imposed by changing environmental statistics. This article proposes that a shared circuit design for such flexible decision-making is used in specific cognitive and motor circuits, and that both types of circuits use acetylcholine to modulate choice selectivity. Such task-sensitive control is proposed to control thalamocortical choice of the critical features that are cognitively attended and that are incorporated through learning into prototypes of visual recognition categories. A cholinergically-modulated process of vigilance control determines if a recognition category and its attended features are abstract (low vigilance) or concrete (high vigilance). Homologous neural mechanisms of cholinergic modulation are proposed to focus attention and learn a multimodal map within the deeper layers of superior colliculus. This map enables visual, auditory, and planned movement commands to compete for attention, leading to selection of a winning position that controls where the next saccadic eye movement will go. Such map learning may be viewed as a kind of attentive motor category learning. The article hereby explicates a link between attention, learning, and cholinergic modulation during decision making within both cognitive and motor systems. Homologs between the mammalian superior colliculus and the avian optic tectum lead to predictions about how multimodal map learning may occur in the mammalian and avian brain and how such learning may be modulated by acetycholine. PMID:26834535

  6. Nucleus Accumbens Invulnerability to Methamphetamine Neurotoxicity

    PubMed Central

    Kuhn, Donald M.; Angoa-Pérez, Mariana; Thomas, David M.

    2016-01-01

    Methamphetamine (Meth) is a neurotoxic drug of abuse that damages neurons and nerve endings throughout the central nervous system. Emerging studies of human Meth addicts using both postmortem analyses of brain tissue and noninvasive imaging studies of intact brains have confirmed that Meth causes persistent structural abnormalities. Animal and human studies have also defined a number of significant functional problems and comorbid psychiatric disorders associated with long-term Meth abuse. This review summarizes the salient features of Meth-induced neurotoxicity with a focus on the dopamine (DA) neuronal system. DA nerve endings in the caudate-putamen (CPu) are damaged by Meth in a highly delimited manner. Even within the CPu, damage is remarkably heterogeneous, with ventral and lateral aspects showing the greatest deficits. The nucleus accumbens (NAc) is largely spared the damage that accompanies binge Meth intoxication, but relatively subtle changes in the disposition of DA in its nerve endings can lead to dramatic increases in Meth-induced toxicity in the CPu and overcome the normal resistance of the NAc to damage. In contrast to the CPu, where DA neuronal deficiencies are persistent, alterations in the NAc show a partial recovery. Animal models have been indispensable in studies of the causes and consequences of Meth neurotoxicity and in the development of new therapies. This research has shown that increases in cytoplasmic DA dramatically broaden the neurotoxic profile of Meth to include brain structures not normally targeted for damage. The resistance of the NAc to Meth-induced neurotoxicity and its ability to recover reveal a fundamentally different neuroplasticity by comparison to the CPu. Recruitment of the NAc as a target of Meth neurotoxicity by alterations in DA homeostasis is significant in light of the numerous important roles played by this brain structure. PMID:23382149

  7. Nucleus accumbens stimulation in pathological obesity.

    PubMed

    Harat, Marek; Rudaś, Marcin; Zieliński, Piotr; Birska, Julita; Sokal, Paweł

    2016-01-01

    One of the potential treatment methods of obesity is deep brain stimulation (DBS) of nucleus accumbens. We describe the case of 19 years old woman with hypothalamic obesity. She weighted 151.4 kg before DBS and the non-surgical methods proved to be inefficient. She was treated with implantation of DBS electrode to nucleus accumbens bilaterally. Results were measured with body mass index and neuropsychological tests. Follow-up was 14 months. Fourteen months after surgery weight was 138 kg, BMI was 48.3. Neuropsychological test results were intact. The presented case supports the thesis of treatment of obesity with nucleus accumbens stimulation. PMID:27154450

  8. Directional Selectivity for FM Sweeps in the Suprageniculate Nucleus of the Mustached Bat Medial Geniculate Body

    PubMed Central

    O’NEILL, WILLIAM E.; BRIMIJOIN, W. OWEN

    2014-01-01

    Mustached bats emit echolocation and communication calls containing both constant frequency (CF) and frequency-modulated (FM) components. Previously we found that 86% of neurons in the ventral division of the external nucleus of the inferior colliculus (ICXv) were directionally selective for linear FM sweeps and that selectivity was dependent on sweep rate. The ICXv projects to the suprageniculate nucleus (Sg) of the medial geniculate body. In this study, we isolated 37 single units in the Sg and measured their responses to best excitatory frequency (BEF) tones and linear 12-kHz upward and downward FM sweeps centered on the BEF. Sweeps were presented at durations of 30, 12, and 4 ms, yielding modulation rates of 400, 1,000, and 3,000 kHz/s. Spike count versus level functions were obtained at each modulation rate and compared with BEF controls. Sg units responded well to both tones and FM sweeps. BEFs clustered at 58 kHz, corresponding to the dominant CF component of the sonar signal. Spike count functions for both tones and sweeps were predominantly non-monotonic. FM directional selectivity was significant in 53–78% of the units, depending on modulation rate and level. Units were classified as up-selective (52%), down-selective (24%), or bi-directional (non-selective, 16%); a few units (8%) showed preferences that were either rate- or level-dependent. Most units showed consistent directional preferences at all SPLs and modulation rates tested, but typically showed stronger selectivity at lower sweep rates. Directional preferences were attributable to suppression of activity by sweeps in the non-preferred direction (~80% of units) and/or facilitation by sweeps in the preferred direction (~20–30%). Latencies for BEF tones ranged from 4.9 to 25.7 ms. Latencies for FM sweeps typically varied linearly with sweep duration. Most FM latency-duration functions had slopes ranging from 0.4 to 0.6, suggesting that the responses were triggered by the BEF. Latencies for BEF

  9. Directional selectivity for FM sweeps in the suprageniculate nucleus of the mustached bat medial geniculate body.

    PubMed

    O'Neill, William E; Brimijoin, W Owen

    2002-07-01

    Mustached bats emit echolocation and communication calls containing both constant frequency (CF) and frequency-modulated (FM) components. Previously we found that 86% of neurons in the ventral division of the external nucleus of the inferior colliculus (ICXv) were directionally selective for linear FM sweeps and that selectivity was dependent on sweep rate. The ICXv projects to the suprageniculate nucleus (Sg) of the medial geniculate body. In this study, we isolated 37 single units in the Sg and measured their responses to best excitatory frequency (BEF) tones and linear 12-kHz upward and downward FM sweeps centered on the BEF. Sweeps were presented at durations of 30, 12, and 4 ms, yielding modulation rates of 400, 1,000, and 3,000 kHz/s. Spike count versus level functions were obtained at each modulation rate and compared with BEF controls. Sg units responded well to both tones and FM sweeps. BEFs clustered at 58 kHz, corresponding to the dominant CF component of the sonar signal. Spike count functions for both tones and sweeps were predominantly non-monotonic. FM directional selectivity was significant in 53-78% of the units, depending on modulation rate and level. Units were classified as up-selective (52%), down-selective (24%), or bi-directional (non-selective, 16%); a few units (8%) showed preferences that were either rate- or level-dependent. Most units showed consistent directional preferences at all SPLs and modulation rates tested, but typically showed stronger selectivity at lower sweep rates. Directional preferences were attributable to suppression of activity by sweeps in the non-preferred direction (~80% of units) and/or facilitation by sweeps in the preferred direction (~20-30%). Latencies for BEF tones ranged from 4.9 to 25.7 ms. Latencies for FM sweeps typically varied linearly with sweep duration. Most FM latency-duration functions had slopes ranging from 0.4 to 0.6, suggesting that the responses were triggered by the BEF. Latencies for BEF

  10. Chronic microstimulation in the feline ventral cochlear nucleus: physiologic and histologic effects.

    PubMed

    McCreery, D B; Yuen, T G; Bullara, L A

    2000-11-01

    This study was conducted to help to establish the feasibility of a multi-channel auditory prosthesis based on microstimulation within the human ventral cochlear nucleus, and to define the range of stimulus parameters that can be used safely with such a device. We chronically implanted activated iridium microelectrodes into the feline ventral cochlear nucleus and, beginning 80-250 days after implantation, they were pulsed for 7 h/day, on up to 21 successive days. The stimulus was charge-balanced pulses whose amplitude was modulated by a simulated human voice. The pulse rate (250 Hz/electrode) and the maximum pulse amplitude were selected as those that are likely to provide a patient with useful auditory percepts. The changes in neuronal responses during the multi-day stimulation regimens were partitioned into long-lasting, stimulation-induced depression of neuronal excitability (SIDNE), and short-acting neuronal refractivity (SANR). Both SIDNE and SANR were quantified from the changes in the growth functions of the evoked potentials recorded in the inferior colliculus. All of the stimulation regimens that we tested induced measurable SIDNE and SANR. The combined effect of SIDNE and the superimposed SANR is to depress the neuronal response near threshold, and thereby, to depress the population response over the entire amplitude range of the stimulus pulses. SIDNE and SANR may cause the greatest degradation of the performance of a clinical device at the low end of the amplitude range, and this may represent an inherent limitation of this type of spatially localized, high-rate neuronal stimulation. We determined sets of stimulus parameters which preserved most of the dynamic range of the neuronal response, when using either long (150 micros/phase) or short (40 micros/phase) stimulus pulses. Increasing the amplitude of the stimulus was relatively ineffective as a means of increasing the dynamic range of neuronal response, since the greater stimulus amplitude induced

  11. Convergence of limb, visceral, and vertical semicircular canal or otolith inputs onto vestibular nucleus neurons

    NASA Technical Reports Server (NTRS)

    Jian, B. J.; Shintani, T.; Emanuel, B. A.; Yates, B. J.

    2002-01-01

    The major goal of this study was to determine the patterns of convergence of non-labyrinthine inputs from the limbs and viscera onto vestibular nucleus neurons receiving signals from vertical semicircular canals or otolith organs. A secondary aim was to ascertain whether the effects of non-labyrinthine inputs on the activity of vestibular nucleus neurons is affected by bilateral peripheral vestibular lesions. The majority (72%) of vestibular nucleus neurons in labyrinth-intact animals whose firing was modulated by vertical rotations responded to electrical stimulation of limb and/or visceral nerves. The activity of even more vestibular nucleus neurons (93%) was affected by limb or visceral nerve stimulation in chronically labyrinthectomized preparations. Some neurons received non-labyrinthine inputs from a variety of peripheral sources, including antagonist muscles acting at the same joint, whereas others received inputs from more limited sources. There was no apparent relationship between the spatial and dynamic properties of a neuron's responses to tilts in vertical planes and the non-labyrinthine inputs that it received. These data suggest that non-labyrinthine inputs elicited during movement will modulate the processing of information by the central vestibular system, and may contribute to the recovery of spontaneous activity of vestibular nucleus neurons following peripheral vestibular lesions. Furthermore, some vestibular nucleus neurons with non-labyrinthine inputs may be activated only during particular behaviors that elicit a specific combination of limb and visceral inputs.

  12. Convergence of limb, visceral, and vertical semicircular canal or otolith inputs onto vestibular nucleus neurons.

    PubMed

    Jian, B J; Shintani, T; Emanuel, B A; Yates, B J

    2002-05-01

    The major goal of this study was to determine the patterns of convergence of non-labyrinthine inputs from the limbs and viscera onto vestibular nucleus neurons receiving signals from vertical semicircular canals or otolith organs. A secondary aim was to ascertain whether the effects of non-labyrinthine inputs on the activity of vestibular nucleus neurons is affected by bilateral peripheral vestibular lesions. The majority (72%) of vestibular nucleus neurons in labyrinth-intact animals whose firing was modulated by vertical rotations responded to electrical stimulation of limb and/or visceral nerves. The activity of even more vestibular nucleus neurons (93%) was affected by limb or visceral nerve stimulation in chronically labyrinthectomized preparations. Some neurons received non-labyrinthine inputs from a variety of peripheral sources, including antagonist muscles acting at the same joint, whereas others received inputs from more limited sources. There was no apparent relationship between the spatial and dynamic properties of a neuron's responses to tilts in vertical planes and the non-labyrinthine inputs that it received. These data suggest that non-labyrinthine inputs elicited during movement will modulate the processing of information by the central vestibular system, and may contribute to the recovery of spontaneous activity of vestibular nucleus neurons following peripheral vestibular lesions. Furthermore, some vestibular nucleus neurons with non-labyrinthine inputs may be activated only during particular behaviors that elicit a specific combination of limb and visceral inputs. PMID:12012162

  13. Dynamic risk control by human nucleus accumbens.

    PubMed

    Nachev, Parashkev; Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio; Strange, Bryan

    2015-12-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established. PMID:26428667

  14. Signs of interaction of the NGC 1275 nucleus with the high-velocity system according to 0.7 sec seeing observations

    NASA Technical Reports Server (NTRS)

    Dudinov, V. N.; Tsvetkova, V. S.; Novikov, S. B.; Pronik, I. I.

    1990-01-01

    The nucleus of the Seyfert galaxy NGC 1275 was observed in the B system on 1 December 1989 with seeing 0, 7 seconds using the Zeiss-1000 telescope on Mount Majdanak in Central Asia. Special methods of processing reveal low-contrast details. The nucleus and circumnucleus are stretched in NW-SE direction. There are two narrow filaments near the nucleus in position angles roughly 340 degrees and 320 degrees. The first is directed near the radio jet of the nucleus, the second has broken details curved to the NW or toward the high-velocity system of NGC 1275.

  15. Comet 19P/Borrelly in Three Dimensions: Coma and Nucleus

    NASA Astrophysics Data System (ADS)

    Soderblom, L. A.

    2002-12-01

    On September 22, 2001 the ion propulsion-powered NASA-JPL Deep Space 1 (DS1) spacecraft passed 2171 km from the nucleus of 19P/Borrelly with a relative velocity of 16.5 km/sec. The advanced technology Miniature Integrated Camera and Spectrometer (MICAS) aboard DS1, collected 25 high resolution images of the coma, jets and nucleus of the Jupiter-family short-period comet. These images were acquired at over a wide range of phase angles allowing detailed characterization of the surface topography of the nucleus, the three-dimensional characteristics of the coma, and the relationships between the two. The very low albedo, elongate nucleus exhibits large albedo variations and complex geology. Observations starting a few days before and extending up to encounter show a prominent jet emanating roughly normal to long axis of nucleus from a broad central depression into a direction about 35 degrees from the sun line (RA: 223 degrees and DEC: -15 degrees). Both fan-like and highly collimated jets are observed in the near-nucleus coma. The collimated jets have cylindrical cores (about 0.5 km x 5 km in dimension) and bubble-shaped bright bases; two are traceable to darker circular patches on the nucleus. The main jet is evidently co-aligned with the rotation axis. This places the sub-solar point only 30 degrees from the pole and, therefore, the pole is in constant sunlight around perihelion. Such an orientation for the pole would also represent a stable rotation of the nucleus around its short axis.

  16. Testing string dynamics in lepton nucleus reactions

    SciTech Connect

    Gyulassy, M.; Pluemer, M.

    1989-10-01

    The sensitivity of nuclear attenuation of 10-100 GeV lepton nucleus ({ell}A) reactions to space-time aspects of hadronization is investigated within the context of the Lund string model. We consider two mechanisms for attenuation in a nucleus: final state cascading and string flip excitations. Implications for the evolution of the energy density in nuclear collisions are discussed. 16 refs., 10 figs.

  17. Commissural axons of the mouse cochlear nucleus.

    PubMed

    Brown, M Christian; Drottar, Marie; Benson, Thane E; Darrow, Keith

    2013-05-01

    The axons of commissural neurons that project from one cochlear nucleus to the other were studied after labeling with anterograde tracer. Injections were made into the dorsal subdivision of the cochlear nucleus in order to restrict labeling only to the group of commissural neurons that gave off collaterals to, or were located in, this subdivision. The number of labeled commissural axons in each injection was correlated with the number of labeled radiate multipolar neurons, suggesting radiate neurons as the predominant origin of the axons. The radiate commissural axons are thick and myelinated, and they exit the dorsal acoustic stria of the injected cochlear nucleus to cross the brainstem in the dorsal half, near the crossing position of the olivocochlear bundle. They enter the opposite cochlear nucleus via the dorsal and ventral acoustic stria and at its medial border. Reconstructions of single axons demonstrate that terminations are mostly in the core and typically within a single subdivision of the cochlear nucleus. Extents of termination range from narrow to broad along both the dorsoventral (i.e., tonotopic) and the rostrocaudal dimensions. In the electron microscope, labeled swellings form synapses that are symmetric (in that there is little postsynaptic density), a characteristic of inhibitory synapses. Our labeled axons do not appear to include excitatory commissural axons that end in edge regions of the nucleus. Radiate commissural axons could mediate the broadband inhibition observed in responses to contralateral sound, and they may balance input from the two ears with a quick time course. PMID:23124982

  18. Improved Cloud Condensation Nucleus Spectrometer

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2010-01-01

    An improved thermal-gradient cloud condensation nucleus spectrometer (CCNS) has been designed to provide several enhancements over prior thermal- gradient counters, including fast response and high-sensitivity detection covering a wide range of supersaturations. CCNSs are used in laboratory research on the relationships among aerosols, supersaturation of air, and the formation of clouds. The operational characteristics of prior counters are such that it takes long times to determine aerosol critical supersaturations. Hence, there is a need for a CCNS capable of rapid scanning through a wide range of supersaturations. The present improved CCNS satisfies this need. The improved thermal-gradient CCNS (see Figure 1) incorporates the following notable features: a) The main chamber is bounded on the top and bottom by parallel thick copper plates, which are joined by a thermally conductive vertical wall on one side and a thermally nonconductive wall on the opposite side. b) To establish a temperature gradient needed to establish a supersaturation gradient, water at two different regulated temperatures is pumped through tubes along the edges of the copper plates at the thermally-nonconductive-wall side. Figure 2 presents an example of temperature and supersaturation gradients for one combination of regulated temperatures at the thermally-nonconductive-wall edges of the copper plates. c) To enable measurement of the temperature gradient, ten thermocouples are cemented to the external surfaces of the copper plates (five on the top plate and five on the bottom plate), spaced at equal intervals along the width axis of the main chamber near the outlet end. d) Pieces of filter paper or cotton felt are cemented onto the interior surfaces of the copper plates and, prior to each experimental run, are saturated with water to establish a supersaturation field inside the main chamber. e) A flow of monodisperse aerosol and a dilution flow of humid air are introduced into the main

  19. Inclusive jet production in ultrarelativistic proton-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Perepelitsa, Dennis V.

    High-pT processes in proton- and deuteron-nucleus collisions at TeV energies are the best presently available way to study the partonic structure of the nucleus in a high-density regime. Jet production over a wide range of phase space can significantly constrain the current knowledge of nuclear parton distribution functions (nPDFs), which are substantially less well understood than the corresponding PDFs in protons and which have only recently begun to be treated in a spatially-dependent way. An accurate knowledge of nPDFs is crucial for a definitive control of perturbative processes in a cold nuclear environment, since high-pT probes are used to quantitatively investigate the hot QCD matter created in ultrarelativistic nucleus-nucleus collisions. Furthermore, jets from low Bjorken-x partons can probe the transition from the dilute to saturated nuclear regimes. Jet production is investigated in d+Au collisions at √s = 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), and in p+Pb collisions at √s = 5.02 TeV with the ATLAS detector at the Large Hadron Collider (LHC). The measurements shown here utilize ∫Ldt = 23 nb-1 and 0.2 pb-1 of 200 GeV d+Au and pp data, respectively, recorded in 2007-8 at RHIC and ∫Ldt = 31 nb -1 and 4.1 pb-1 of 5.02 TeV p+Pb and 2.76 TeV pp data, respectively, recorded in 2013 at the LHC. Jets are reconstructed using the sigma=0.3 Gaussian filter and R=0.4, 0.6 anti-kT algorithms. Inclusive, centrality-dependent jet yields within |eta| < 0.35 and 10 GeV < p T < 40 GeV in 200 GeV d+Au and pp collisions are presented. The jet yield in d+Au collisions relative to the geometric expectation is found to be slightly suppressed (≍0.9) in central events and moderately enhanced (≍1.3) in peripheral events, with no modification when averaged over all d+Au events. Separately, inclusive, centrality-dependent jet yields within |y *| < 4.4 and 25 GeV < pT < 800 GeV in 5.02 TeV p+Pb and 2.76 TeV pp collisions are

  20. Torsional ultrasound modality for hard nucleus phacoemulsification cataract extraction

    PubMed Central

    Zeng, M; Liu, X; Liu, Y; Xia, Y; Luo, L; Yuan, Z; Zeng, Y; Liu, Y

    2008-01-01

    Aim: To evaluate the efficacy and safety of phacoemulsification using torsional modality with different parameter settings for hard nucleus cataract extraction. Design: A prospective, randomised clinical study. Methods: A clinical practice study conducted at the Cataract Service, Zhongshan Ophthalmic Center, Sun-Yat-Sen University, and Guangzhou. One eye each from 198 consecutive patients with cataract density grade IV according to the Emery–Little system classification system, requiring phacoemulsification and intraocular lens implantation, was included. Eyes were randomly assigned to the Linear Torsional combined with Ultrasound power group (Linear Tor+US group, n = 66), 100% Fixed Torsional group (Fixed Tor group, n = 65) and conventional Ultrasound burst group (US group, n = 67). All surgeries were performed by a single experienced surgeon and outcomes evaluated by another surgeon masked to treatment. Intraoperative parameters were Ultrasound Time (UST), Cumulative Dissipated Energy (CDE) and surgical complications. Patients were examined on post-op days 1, 7 and 30. Postoperative outcomes were final best corrected visual acuity (BCVA), average central and incisional corneal thickness and central endothelial cell counts. Results: The mean UST was lower in the Fixed Tor group than in the US group and in the Lin US+Tor group (p⩽0.0001). The mean CDE was lower in the Lin Tor+US group and in the Fixed Tor group than in the US group (p⩽0.0001). Comparing with the two Tor group, the US group had a lower average BCVA on post-op 1, 7 (p⩽0.0001) and 30 (p>0.01), greater average central corneal and incisional thickness on days 1, 7 (p⩽0.0001) and 30 (p>0.01), and higher average corneal endothelial cell losses on day 7 and 30 days (p⩽0.0001). Conclusions: Torsional combined with ultrasound power or high fixed torsional amplitude can yield more effective hard nucleus phacoemulsification than conventional ultrasound modality. PMID:18567650

  1. 3200 Phaethon, Asteroid or Comet Nucleus?

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Benkhoff, Johannes

    2015-08-01

    Physico-chemical modeling is central to understand the important physical processes in small solar system bodies. We have developed a computer simulation, SUISEI, that includes the physico-chemical processes relevant to comets within a global modeling framework. Our goals are to gain valuable insights into the intrinsic properties of cometary nuclei so we can better understand observations and in situ measurements. SUISEI includes a 3-D model of gas and heat transport in porous sub-surface layers in the interior of the nucleus.We present results on the application of SUISEI to the near-Sun object, Phaethon. Discovered in 1983 and classified as an asteroid, it has recently exhibited an active dust coma. Phaethon has long been associated as the source of the Geminids meteor shower so the dust activity provides a clear link to the meteor shower. The observed dust activity would traditionally lead to Phaethon being also classified as a comet (e.g., 2060-95P/Chiron, 133P/Elst-Pizarro). This is unusual since the orbit of Phaethon has a perihelion of 0.14 AU, resulting in surface temperatures of more than 1025K, much too hot for water ice or other volatiles to exist near the surface and drive the activity. This situation and others such as the “Active Asteroids” necessitates a revision of how we understand and classify these small asteroid-comet transition objects.We conclude the following for Phaethon:1. It is likely to contain relatively pristine volatiles in its interior despite repeated near perihelion passages of 0.14 AU during its history in its present orbit,2. Steady water gas fluxes at perihelion and throughout its orbit are insufficient to entrain the currently observed dust production,3. Thermal gradients into the surface as well as those caused by diurnal rotation are consistent with the mechanism of dust release due to thermal fracture,4. The initial large gas release during the first perihelion passage may be sufficient to produce enough dust to explain

  2. Computer program for parameterization of nucleus-nucleus electromagnetic dissociation cross sections

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.; Badavi, Forooz F.

    1988-01-01

    A computer subroutine parameterization of electromagnetic dissociation cross sections for nucleus-nucleus collisions is presented that is suitable for implementation in a heavy ion transport code. The only inputs required are the projectile kinetic energy and the projectile and target charge and mass numbers.

  3. Irisin evokes bradycardia by activating cardiac-projecting neurons of nucleus ambiguus

    PubMed Central

    Brailoiu, Eugen; Deliu, Elena; Sporici, Romeo A; Cristina Brailoiu, G

    2015-01-01

    Irisin is a newly identified hormone induced in muscle and adipose tissues by physical activity. This protein and its encoding gene have been identified in the brain; in addition, the precursor for irisin, FNDC5, can cross the blood-brain barrier. The fact that irisin is secreted during exercise together with the lower resting heart rate in athletes prompted us to investigate the effect of irisin on cardiac-projecting vagal neurons of nucleus ambiguus, a key regulatory site of heart rate. In vitro experiments in cultured nucleus ambiguus neurons indicate that irisin activates these neurons, inducing an increase in cytosolic Ca2+ concentration and neuronal depolarization. In vivo microinjection of irisin into the nucleus ambiguus promotes bradycardia in conscious rats. Our study is the first to report the effects of irisin on the neurons controlling the cardiac vagal tone and to link a myokine to a cardioprotective role, by modulating central cardiovascular regulation. PMID:26038469

  4. A Model of Comet Nucleus Rotation

    NASA Astrophysics Data System (ADS)

    Keller, H. U.; Jorda, L.; Rickman, H.; Thomas, N.

    2000-10-01

    Modelling cometary rotation is of particular interest for the preparation of space missions to comets. For example, the mapping phase during the ROSETTA mission must be planned keeping in mind that, unlike most asteroids, the rotational state of most short-period comets might be complex (excited). The modelling of cometary nucleus rotation can also provide us with important parameters that are needed to interpret coma structures or to build time-dependent thermal models of the nucleus. We combine a general three-dimensional model for the nucleus shape, surface properties, and insolation with a simplified thermal model to calculate the local time-dependent activity and consequently the non-gravitational forces acting on the nucleus. The torque of this force is then used to numerically solve the forced Euler equations for a homogeneously outgassing irregularly-shaped cometary nucleus. We will discuss the results of our model for comets 46P/Wirtanen, the target of the ROSETTA mission, and 19P/Borrelly, the target of DEEP-SPACE 1 and derive some generalized inferences.

  5. Effects of pulsatile electrical stimulation of the round window on central hyperactivity after cochlear trauma in guinea pig.

    PubMed

    Mulders, W H A M; Spencer, T C; Robertson, D

    2016-05-01

    Partial hearing loss induced by acoustic trauma has been shown in animal models to result in an increased spontaneous firing rate in central auditory structures. This so-called hyperactivity has been suggested to be involved in the generation of tinnitus, a phantom auditory sensation. Although there is no universal cure for tinnitus, electrical stimulation of the cochlea, as achieved by a cochlear implant, can result in significant reduction of the tinnitus percept. However, the mechanism by which this tinnitus suppression occurs is as yet unknown and furthermore cochlear implantation may not be an optimal treatment option for tinnitus sufferers who are not profoundly deaf. A better understanding of the mechanism of tinnitus suppression by electrical stimulation of the cochlea, may lead to the development of more specialised devices for those for whom a cochlear implant is not appropriate. This study aimed to investigate the effects of electrical stimulation in the form of brief biphasic shocks delivered to the round window of the cochlea on the spontaneous firing rates of hyperactive inferior colliculus neurons following acoustic trauma in guinea pigs. Effects during the stimulation itself included both inhibition and excitation but spontaneous firing was suppressed for up to hundreds of ms after the cessation of the shock train in all sampled hyperactive neurons. Pharmacological block of olivocochlear efferent action on outer hair cells did not eliminate the prolonged suppression observed in inferior colliculus neurons, and it is therefore likely that activation of the afferent pathways is responsible for the central effects observed. PMID:26970475

  6. Eccentric-Disk Models for the Nucleus of M31

    NASA Astrophysics Data System (ADS)

    Peiris, Hiranya V.; Tremaine, Scott

    2003-12-01

    We construct dynamical models of the ``double'' nucleus of M31 in which the nucleus consists of an eccentric disk of stars orbiting a central black hole. The principal approximation in these models is that the disk stars travel in a Keplerian potential; i.e., we neglect the mass of the disk relative to the black hole. We consider both ``aligned'' models, in which the eccentric disk lies in the plane of the large-scale M31 disk, and ``nonaligned'' models, in which the orientation of the eccentric disk is fitted to the data. Both types of model can reproduce the double structure and overall morphology seen in Hubble Space Telescope photometry. In comparison with the best available ground-based spectroscopy, the models reproduce the asymmetric rotation curve, the peak height of the dispersion profile, and the qualitative behavior of the Gauss-Hermite coefficients h3 and h4. Aligned models fail to reproduce the observation that the surface brightness at P1 is higher than at P2 and yield significantly poorer fits to the kinematics; thus, we favor nonaligned models. Eccentric-disk models fitted to ground-based spectroscopy are used to predict the kinematics observed at much higher resolution by the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, and we find generally satisfactory agreement.

  7. Protein quality control in the nucleus.

    PubMed

    Jones, Ramon D; Gardner, Richard G

    2016-06-01

    The nucleus is the repository for the eukaryotic cell's genetic blueprint, which must be protected from harm to ensure survival. Multiple quality control (QC) pathways operate in the nucleus to maintain the integrity of the DNA, the fidelity of the DNA code during replication, its transcription into mRNA, and the functional structure of the proteins that are required for DNA maintenance, mRNA transcription, and other important nuclear processes. Although we understand a great deal about DNA and RNA QC mechanisms, we know far less about nuclear protein quality control (PQC) mechanisms despite that fact that many human diseases are causally linked to protein misfolding in the nucleus. In this review, we discuss what is known about nuclear PQC and we highlight new questions that have emerged from recent developments in nuclear PQC studies. PMID:27015023

  8. Interpretive monitoring in the caudate nucleus

    PubMed Central

    Yanike, Marianna; Ferrera, Vincent P

    2014-01-01

    In a dynamic environment an organism has to constantly adjust ongoing behavior to adapt to a given context. This process requires continuous monitoring of ongoing behavior to provide its meaningful interpretation. The caudate nucleus is known to have a role in behavioral monitoring, but the nature of these signals during dynamic behavior is still unclear. We recorded neuronal activity in the caudate nucleus in monkeys during categorization behavior that changed rapidly across contexts. We found that neuronal activity maintained representation of the identity and context of a recently categorized stimulus, as well as interpreted the behavioral meaningfulness of the maintained trace. The accuracy of this cognitive monitoring signal was highest for behavior for which subjects were prone to make errors. Thus, the caudate nucleus provides interpretive monitoring of ongoing behavior, which is necessary for contextually specific decisions to adapt to rapidly changing conditions. DOI: http://dx.doi.org/10.7554/eLife.03727.001 PMID:25415238

  9. Near-infrared imaging of Markarian 231: Evidence for a double nucleus

    NASA Technical Reports Server (NTRS)

    Armus, L.; Surace, J. A.; Soifer, B. T.; Matthews, K.; Graham, J. R.; Larkin, J. E.

    1994-01-01

    Near-infrared (1.2-2.4 micrometers) images are presented for the central 10 arcsec of the Seyfert 1 galaxy Markarian 231. We find a faint, but intrinsically luminous (M(sub k) approximately -20.7) secondary peak in the near-infrared light distribution approximately 3.5 arcsec (2.7 kpc) south of the primary Seyfert 1 nucleus. Since there is no optical or infrared evidence for ongoing star formation at the location of this secondary peak, and its near-infrared luminosity and color are comparable to slightly reddened spiral bulges or elliptical nuclei, we identify this peak with the stripped nucleus of the companion galaxy involved in the Mrk 231 merger event. Depending upon the exact ratio of the masses of the primary and secondary nucleus in the Mrk 231 system we estimate a merger time scale of less than or equal to 10(exp 9) yr. The morphology of the southern nucleus suggests that it may have recently survived a close passage (r less than 200 pc) with the Seyfert 1 nucleus on a highly elliptical orbit, in which case the merger time scale may be significantly shorter (approximately 10(exp 7) yr. We re-calculate the average merger time scale for the seven ultraluminous infrared galaxies with double nuclei in the Bright Galaxy Sample (the BGS) of Soifer et al. (AJ, 98, 766 (1989)) and derive a value of approximately 10(exp 8) yr. Since seven of ten of the ultraluminous infrared galaxies in the BGS are now known to be double, we estimate the ultraluminous 'phase' may be close to this value. Along with Arp 220 and Mrk 273, Mrk 231 is the third member of the class to possess a high brightness temperature non-thermal radio core and a double nucleus, suggesting the time scale for the generation or fueling of the active nucleus can be much less than the dynamical time scale for the merger of the progenitor nuclei.

  10. Nucleus accumbens dopaminergic neurotransmission switches its modulatory action in chronification of inflammatory hyperalgesia.

    PubMed

    Dias, Elayne Vieira; Sartori, César Renato; Marião, Paula Ramos; Vieira, André Schwambach; Camargo, Lilian Calili; Athie, Maria Carolina Pedro; Pagliusi, Marco Oreste; Tambeli, Claudia Herrera; Parada, Carlos Amilcar

    2015-10-01

    Dopaminergic neurotransmission in the nucleus accumbens, a central component of the mesolimbic system, has been associated with acute pain modulation. As there is a transition from acute to chronic pain ('chronification'), modulatory structures may be involved in chronic pain development. Thus, this study aimed to elucidate the role of nucleus accumbens dopaminergic neurotransmission in chronification of pain. We used a rat model in which daily subcutaneous injection of prostaglandin E2 in the hindpaw for 14 days induces a long-lasting state of nociceptor sensitization that lasts for at least 30 days following the end of the treatment. Our findings demonstrated that the increase of dopamine in the nucleus accumbens by local administration of GBR12909 (0.5 nmol/0.25 μL), a dopamine reuptake inhibitor, blocked prostaglandin E2 -induced acute hyperalgesia. This blockade was prevented by a dopamine D2 receptor antagonist (raclopride, 10 nmol/0.25 μL) but not changed by a D1 receptor antagonist (SCH23390, 0.5, 3 or 10 nmol/0.25 μL), both co-administered with GBR12909 in the nucleus accumbens. In contrast, the induction of persistent hyperalgesia was facilitated by continuous infusion of GBR12909 in the nucleus accumbens (0.021 nmol/0.5 μL/h) over 7 days of prostaglandin E2 treatment. The development of persistent hyperalgesia was impaired by SCH23390 (0.125 nmol/0.5 μL/h) and raclopride (0.416 nmol/0.5 μL/h), both administered continuously in the nucleus accumbens over 7 days. Taken together, our data suggest that the chronification of pain involves the plasticity of dopaminergic neurotransmission in the nucleus accumbens, which switches its modulatory role from antinociceptive to pronociceptive. PMID:26173870

  11. Sigma-nucleus potential in A=28.

    PubMed

    Noumi, H; Saha, P K; Abe, D; Ajimura, S; Aoki, K; Bhang, H C; Endo, T; Fujii, Y; Fukuda, T; Guo, H C; Imai, K; Hashimoto, O; Hotchi, H; Kim, E H; Kim, J H; Kishimoto, T; Krutenkova, A; Maeda, K; Nagae, T; Nakamura, M; Outa, H; Sekimoto, M; Saito, T; Sakaguchi, A; Sato, Y; Sawafta, R; Shimizu, Y; Takahashi, T; Tang, L; Tamura, H; Tanida, K; Watanabe, T; Xia, H H; Zhou, S H; Zhu, L H; Zhu, X F

    2002-08-12

    We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum. PMID:12190516

  12. Nucleus model for periodic Comet Tempel 2

    NASA Technical Reports Server (NTRS)

    Sekanina, Zdenek

    1991-01-01

    Observational data obtained primarily during 1988 are analyzed and synthesized to develop a comprehensive physical model for the nucleus of Periodic Comet Tempel 2, one of the best studied members of Jupiter's family of short-period comets. It is confirmed that a previous investigation provided reliable information on the comet's spin-axis orientation, which implies and obliquity of 54 degrees of the orbit plane to the equatorial plane and which appears to have varied little - if at all - with time. This conclusion is critical for fitting a triaxial ellipsoid to approximate the figure of the nucleus.

  13. Hydrated nucleus pulposus herniation in seven dogs.

    PubMed

    Manunta, M L; Evangelisti, M A; Bergknut, N; Grinwis, G C M; Ballocco, I; Meij, B P

    2015-03-01

    The clinical signs, magnetic resonance imaging (MRI) findings, treatment and follow-up in seven dogs with hydrated nucleus pulposus extrusion (HNPE) are reported. All dogs had tetraparesis or tetraplegia. T2-weighted MRI revealed extradural hyperintense homogeneous material compressing the cervical spinal cord. After conservative treatment (five dogs) or surgical decompression (two dogs), all dogs returned to ambulatory function within 1 month. Follow-up MRI in conservatively treated dogs revealed complete disappearance of the extruded material. Histopathological examination of surgical specimens confirmed that the retrieved material was extruded nucleus pulposus with evidence of early degeneration. PMID:25599897

  14. The suprachiasmatic nucleus: age-related decline in biological rhythms.

    PubMed

    Nakamura, Takahiro J; Takasu, Nana N; Nakamura, Wataru

    2016-09-01

    Aging is associated with changes in sleep duration and quality, as well as increased rates of pathologic/disordered sleep. While several factors contribute to these changes, emerging research suggests that age-related changes in the mammalian central circadian clock within the suprachiasmatic nucleus (SCN) may be a key factor. Prior work from our group suggests that circadian output from the SCN declines because of aging. Furthermore, we have previously observed age-related infertility in female mice, caused by a mismatch between environmental light-dark cycles and the intrinsic, internal biological clocks. In this review, we address regulatory mechanisms underlying circadian rhythms in mammals and summarize recent literature describing the effects of aging on the circadian system. PMID:26915078

  15. Star formation in the nucleus of NGC 253

    NASA Technical Reports Server (NTRS)

    Beck, S. C.; Beckwith, S. V.

    1984-01-01

    The B-alpha and B-gamma lines of atomic hydrogen have been observed at eight positions near the nucleus of NGC 253 with 6 arcsec spatial resolution. Most if not all of the bolometric luminosity of the central 200 pc of this galaxy is probably produced by O and B stars which have recently formed. The spatial distribution of the line fluxes is similar to that of the 10 microns flux, supporting the hypothesis that the 10 microns radiation is powered by the newly formed stars. The extinction to the ionized gas varies over small distances in this region, explaining the discrepancies between extinction and Lyman continuum luminosity derived separately from visual and infrared line observations.

  16. Three-hadron angular correlations in high-energy proton-proton and nucleus-nucleus collisions from perturbative QCD

    SciTech Connect

    Ayala, Alejandro; Ortiz, Antonio; Paic, Guy; Jalilian-Marian, Jamal; Magnin, J.; Tejeda-Yeomans, Maria Elena

    2011-08-15

    We study three-hadron azimuthal angular correlations in high-energy proton-proton and central nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider at midrapidity. We use the leading-order parton matrix elements for 2{yields}3 processes and include the effect of parton energy loss in the quark-gluon plasma using the modified fragmentation function approach. For the case when the produced hadrons have either the same or not too different momenta, we observe two away-side peaks at 2{pi}/3 and 4{pi}/3. We consider the dependence of the angular correlations on energy loss parameters that have been used in studies of single inclusive hadron production at RHIC. Our results on the angular dependence of the cross section agree well with preliminary data by the PHENIX Collaboration. We comment on the possible contribution of 2{yields}3 processes to dihadron angular correlations and how a comparison of the two processes may help characterize the plasma further.

  17. Cortical Auditory Deafferentation Induces Long-Term Plasticity in the Inferior Colliculus of Adult Rats: Microarray and qPCR Analysis

    PubMed Central

    Clarkson, Cheryl; Herrero-Turrión, M. Javier; Merchán, Miguel A.

    2012-01-01

    The cortico-collicular pathway is a bilateral excitatory projection from the cortex to the inferior colliculus (IC). It is asymmetric and predominantly ipsilateral. Using microarrays and RT-qPCR we analyzed changes in gene expression in the IC after unilateral lesions of the auditory cortex, comparing the ICs ipsi- and contralateral to the lesioned side. At 15 days after surgery there were mainly changes in gene expression in the IC ipsilateral to the lesion. Regulation primarily involved inflammatory cascade genes, suggesting a direct effect of degeneration rather than a neuronal plastic reorganization. Ninety days after the cortical lesion the ipsilateral IC showed a significant up-regulation of genes involved in apoptosis and axonal regeneration combined with a down-regulation of genes involved in neurotransmission, synaptic growth, and gap junction assembly. In contrast, the contralateral IC at 90 days post-lesion showed an up-regulation in genes primarily related to neurotransmission, cell proliferation, and synaptic growth. There was also a down-regulation in autophagy and neuroprotection genes. These findings suggest that the reorganization in the IC after descending pathway deafferentation is a long-term process involving extensive changes in gene expression regulation. Regulated genes are involved in many different neuronal functions, and the number and gene rearrangement profile seems to depend on the density of loss of the auditory cortical inputs. PMID:23233834

  18. Distribution of NADPH-diaphorase in the superior colliculus of Cebus monkeys, and co-localization with calcium-binding proteins.

    PubMed

    Soares, J G M; Mendez-Otero, R; Gattass, Ricardo

    2003-08-01

    We examined the distribution of the enzyme dihydronicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) in the superior colliculus (SC) of the New World monkey Cebus apella, and the co-localization of this enzyme with the calcium-binding proteins (CaBPs) calbindin-D28K, parvalbumin and calretinin. Despite the intensely labeled neuropil, rare NADPH-d-positive cells were observed in the stratum griseum superficiale (SGS). Most of the labeled cells in the SC were found in the intermediate layers, with a great number also in the deeper layers. This pattern is very similar to that described in the opossum (Didelphis marsupialis) and in the cat, and different from the pattern found in the rat, which shows labeled cells mainly in the SGS. Cells doubly stained for NADPH-d and CaBPs were observed throughout the SC, although in a small number. Of the NADPH-d-positive cells, 20.3% were doubly labeled for NADPH-d and parvalbumin, 10.2% revealed co-localization with calretinin, and 5.6% with calbindin. The low number of double-stained cells for NADPH-d and the CaBPs indicates that these molecules must participate in different functional circuits within the SC. PMID:12871769

  19. Determining auditory-evoked activities from multiple cells in layer 1 of the dorsal cortex of the inferior colliculus of mice by in vivo calcium imaging.

    PubMed

    Ito, Tetsufumi; Hirose, Junichi; Murase, Kazuyuki; Ikeda, Hiroshi

    2014-11-24

    Layer 1 of the dorsal cortex of the inferior colliculus (DCIC) is distinguished from other layers by its cytoarchitecture and fiber connections. However, the information of the sound types represented in layer 1 of the DCIC remains unclear because placing electrodes on such thin structures is challenging. In this study, we utilized in vivo calcium imaging to assess auditory-evoked activities in multiple cells in layer 1 of DCIC and to characterize sound stimuli producing strong activity. Most cells examined showed strong responses to broad-band noise and low-frequency tone bursts of high sound intensity. In some cases, we successfully obtained frequency response areas, which are receptive fields to tone frequencies and intensities, and ~30% of these showed V-shape tunings. This is the first systematic study to record auditory responses of cells in layer 1 of DCIC. These results indicate that cells in this area are selective to tones with low frequency, implying the importance of such auditory information in the neural circuitry of layer 1 of DCIC. PMID:25278189

  20. An fMRI Investigation of Preparatory Set in the Human Cerebral Cortex and Superior Colliculus for Pro- and Anti-Saccades

    PubMed Central

    Furlan, Michele; Smith, Andrew T.; Walker, Robin

    2016-01-01

    Previous studies have identified several cortical regions that show larger BOLD responses during preparation and execution of anti-saccades than pro-saccades. We confirmed this finding with a greater BOLD response for anti-saccades than pro-saccades during the preparation phase in the FEF, IPS and DLPFC and in the FEF and IPS in the execution phase. We then applied multi-voxel pattern analysis (MVPA) to establish whether different neural populations are involved in the two types of saccade. Pro-saccades and anti-saccades were reliably decoded during saccade execution in all three cortical regions (FEF, DLPFC and IPS) and in IPS during saccade preparation. This indicates neural specialization, for programming the desired response depending on the task rule, in these regions. In a further study tailored for imaging the superior colliculus in the midbrain a similar magnitude BOLD response was observed for pro-saccades and anti-saccades and the two saccade types could not be decoded with MVPA. This was the case both for activity related to the preparation phase and also for that elicited during the execution phase. We conclude that separate cortical neural populations are involved in the task-specific programming of a saccade while in contrast, the SC has a role in response preparation but may be less involved in high-level, task-specific aspects of the control of saccades. PMID:27391390

  1. Responses of neurons in the rat's ventral nucleus of the lateral lemniscus to amplitude-modulated tones.

    PubMed

    Zhang, Huiming; Kelly, Jack B

    2006-12-01

    Recordings were made from single neurons in the rat's ventral nucleus of the lateral lemniscus (VNLL) to determine responses to amplitude-modulated (AM) tones. The neurons were first characterized on the basis of their response to tone bursts presented to the contralateral ear and a distinction was made between those with transient onset responses and those with sustained responses. Sinusoidal AM tones were then presented to the contralateral ear with a carrier that matched the neuron's characteristic frequency (CF). Modulation transfer functions were generated on the basis of firing rate (MTF(FR)) and vector strength (MTF(VS)). Ninety-two percent of onset neurons that responded continuously to AM tones had band-pass MTF(FR)s with best modulation frequencies from 10 to 300 Hz. Fifty-four percent of sustained neurons had band-pass MTF(FR)s with best modulation frequencies from 10 to 500 Hz; other neurons had band-suppressed, all-pass, low-pass, or high-pass functions. Most neurons showed either band-pass or low-pass MTF(VS). Responses were well synchronized to the modulation cycle with maximum vector strengths ranging from 0.37 to 0.98 for sustained neurons and 0.78 to 0.99 for onset neurons. The upper frequency limit for response synchrony was higher than that reported for inferior colliculus, but lower than that seen in more peripheral structures. Results suggest that VNLL neurons, especially those with onset responses to tone bursts, are sensitive to temporal features of sounds and narrowly tuned to different modulation rates. However, there was no evidence of a topographic relation between dorsoventral position along the length of VNLL and best modulation frequency as determined by either firing rate or vector strength. PMID:16928797

  2. Antiproton Production in 11.5A GeV/c Au+Pb Nucleus-Nucleus Collisions

    SciTech Connect

    De Cataldo, G.; Giglietto, N.; Raino, A.; Spinelli, P.; Huang, H.Z.; Hill, J.C.; Libby, B.; Wohn, F.K.; Rabin, M.S.; Haridas, P.; Pless, I.A.; Van Buren, G.; Armstrong, T.A.; Lewis, R.A.; Reid, J.D.; Smith, G.A.; Toothacker, W.S.; Davies, R.; Hirsch, A.S.; Porile, N.T.; Rimai, A.; Scharenberg, R.P.; Srivastava, B.K.; Tincknell, M.L.; Greene, S.V.; Bennett, S.J.; Cormier, T.M.; Dee, P.; Fachini, P.; Kim, B.; Li, Q.; Li, Y.; Munhoz, M.G.; Pruneau, C.A.; Wilson, W.K.; Zhao, K.; Barish, K.N.; Bennett, M.J.; Chikanian, A.; Coe, S.D.; Diebold, G.E.; Finch, L.E.; George, N.K.; Kumar, B.S.; Lajoie, J.G.; Majka, R.D.; Nagle, J.L.; Pope, J.K.; Rotondo, F.S.; Sandweiss, J.; Slaughter, A.J.; Wolin, E.J.

    1997-11-01

    We present the first results from the E864 Collaboration on the production of antiprotons in 10{percent} central 11.5A GeV /c Au+Pb nucleus collisions at the Brookhaven Alternating Gradient Synchrotron. We report invariant multiplicities for antiproton production in the kinematic region 1.4{lt}y{lt}2.2 and 50{lt} p{sub T}{lt} 300 MeV/c , and compare our data with a first collision scaling model and previously published results from the E878 Collaboration. The differences between the E864 and E878 antiproton measurements and the implications for antihyperon production are discussed. {copyright} {ital 1997} {ital The American Physical Society}

  3. Compound nucleus studies withy reverse kinematics

    SciTech Connect

    Moretto, L.G.

    1985-06-01

    Reverse kinematics reactions are used to demonstrate the compound nucleus origin of intermediate mass particles at low energies and the extension of the same mechanism at higher energies. No evidence has appeared in our energy range for liquid-vapor equilibrium or cold fragmentation mechanisms. 11 refs., 12 figs.

  4. Coherent elastic neutrino-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Scholberg, Kate

    2015-05-01

    I describe physics potential and experimental prospects for coherent elastic neutrino-nucleus scattering (CEvNS), a process which has not yet been observed. Germanium- based detectors represent a promising technology for CEvNS experiments. I focus primarily on stopped-pion neutrino sources.

  5. Transport model of nucleon-nucleus reaction

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Townsend, L. W.; Cucinotta, F. A.

    1986-01-01

    A simplified model of nucleon-nucleus reaction is developed and some of its properties are examined. Comparisons with proton production measured for targets of Al-27, Ni-58, Zr-90, and Bi-209 show some hope for developing an accurate model for these complex reactions. It is suggested that binding effects are the next step required for further development.

  6. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2015-04-01

    The Checker Board Model (CBM) of the nucleus and the associated extended standard model predicts that nature has 5 generations of quarks not 3 and that Nucleus is 2 dimensional. The CBM theory began with an insight into the structure of the He nucleus around the year 1989. Details of how this theory evolved which took many years, and is found on my web site (http://checkerboard.dnsalias.net) or in the following references One independent check of this model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light (around the ``dn'' quark in the center of the proton) turns out to be exactly one de Broglie wavelength something determined after the mass and speed of the up quark were determined by other means. This theory explains the mass of the proton and neutron and their magnetic moments and this along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. When this theory was first presented at Argonne in 1996, it was the first time that anyone had predicted the quarks orbited inside the proton at relativistic speeds and it was met with skepticism.

  7. The Nucleus and the Simple Microscope.

    ERIC Educational Resources Information Center

    Ford, Brian J.

    1982-01-01

    The 150th anniversary of the naming of the nucleus by Robert Brown in 1831 was commemorated by re-creating some of his most important observations using two of his microscopes. Comments on Brown's career and the microtechnique employed during his time are provided. (Author/JN)

  8. Bilateral inhibition generates neuronal responses tuned to interaural level differences in the auditory brainstem of the barn owl.

    PubMed

    Adolphs, R

    1993-09-01

    I investigated the neural algorithms by which neurons gain selectivity for interaural level difference in the brainstem of the barn owl (Tyto alba). Differences in the timing and in the level of sounds at the ears are used by this owl to encode, respectively, azimuthal and vertical position of sound sources in space. These two cues are processed in two parallel neural pathways. Below the level of the inferior colliculus, all neurons in the pathway that processes level differences show responses to this cue that are monotonic, and thus not selective for a particular level difference. Only in the inferior colliculus, which contains a map of auditory space, are neurons sharply tuned to specific interaural level differences. How are these response properties generated from those of the nuclei that provide input to the inferior colliculus? I show that the posterior subdivision of the nucleus ventralis lemnisci lateralis (VLVp) projects bilaterally to the lateral shell of the central nucleus of the inferior colliculus, the input stage to the map of auditory space. Both these nuclei are part of the pathway that processes interaural level differences. Manipulations of the responses in VLVp affected the responses to level differences in the inferior colliculus; responses to time differences were unaffected. By systematically increasing or decreasing neural activity in VLVp, I show that the VLVp on each side provides inhibition to the colliculus at large level differences. This results in a peaked response that is tuned to level differences in the inferior colliculus. Some cells in the lateral shell of the inferior colliculus appear to receive direct GABAergic inhibition from VLVp. I suggest that this circuitry and the algorithms it supports are the neural substrates that allow the barn owl to exploit level differences for computation of sound source elevation. PMID:7690063

  9. The indirect pathway of the nucleus accumbens shell amplifies neuropathic pain

    PubMed Central

    Ren, Wenjie; Centeno, Maria Virginia; Berger, Sara; Wu, Ying; Na, Xiaodong; Liu, Xianguo; Kondapalli, Jyothisri; Apkarian, A Vania; Martina, Marco; Surmeier, D James

    2016-01-01

    We examined adaptations in nucleus accumbens (NAc) neurons in mouse and rat peripheral nerve injury models of neuropathic pain. Injury selectively increased excitability of NAc shell indirect pathway spiny projection neurons (iSPNs) and altered their synaptic connectivity. Moreover, injury-induced tactile allodynia was reversed by inhibiting and exacerbated by exciting iSPNs, indicating that they not only participated in the central representation of pain, but gated activity in ascending nociceptive pathways. PMID:26691834

  10. Heavy-flavour dynamics in proton-proton and nucleus-nucleus collisions at LHC

    NASA Astrophysics Data System (ADS)

    Nardi, M.; Beraudo, A.; De Pace, A.; Monteno, M.; Prino, F.

    2016-01-01

    We present recent results for heavy-quark observables in nucleus-nucleus collisions at LHC energies, obtained by the POWLANG transport setup. The initial creation of c c ¯ and b b ¯ pairs is simulated with a perturbative QCD approach (POWHEG+PYTHIA) and validated through comparison to experimental data of proton-proton collisions. In the nucleus-nucleus case, the propagation of the heavy quarks in the plasma is studied with the relativistic Langevin equation, here solved using weak-coupling transport-coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor RAA and the elliptic flow v2 of the final D mesons, as well as D - h correlations, and compare our results to experimental data from the ALICE and CMS Collaborations.

  11. The mesopontine rostromedial tegmental nucleus: a structure targeted by the lateral habenula that projects to the ventral tegmental area of Tsai and substantia nigra compacta

    PubMed Central

    Jhou, Thomas C.; Geisler, Stefanie; Marinelli, Michela; DeGarmo, Beth A.; Zahm, Daniel S.

    2011-01-01

    Prior studies revealed that aversive stimuli and psychostimulant drugs elicit Fos expression in neurons clustered above and behind the interpeduncular nucleus that project strongly to the ventral tegmental area (VTA) and substantia nigra (SN) compacta (C). Other reports suggest that these neurons modulate responding to aversive stimuli. We now designate the region containing them as the mesopontine rostromedial tegmental nucleus (RMTg) and report herein on its neuroanatomy. Dense mu opioid receptor and somatostatin immunoreactivity characterize the RMTg, as do neurons projecting to the VTA/SNC that are enriched in GAD 67 mRNA. Strong inputs to the RMTg arise in the lateral habenula (LHb) and, to a lesser extent, the SN. Other inputs come from the frontal cortex, ventral striatopallidum, extended amygdala, septum, preoptic region, lateral, paraventricular and posterior hypothalamus, zona incerta, periaqueductal gray, intermediate layers of the contralateral superior colliculus, dorsal raphe, mesencephalic, pontine and medullary reticular formation, and the following nuclei: parafascicular, supramammillary, mammillary, ventral lateral geniculate, deep mesencephalic, red, pedunculopontine and laterodorsal tegmental, cuneiform, parabrachial and deep cerebellar. The RMTg has meager outputs to the forebrain, mainly to the ventral pallidum, preoptic-lateral hypothalamic continuum and midline-intralaminar thalamus, but much heavier outputs to the brainstem, including, most prominently, the VTA/SNC, as noted above, and to medial tegmentum, pedunculopontine and laterodorsal tegmental nuclei, dorsal raphe and the locus ceruleus and subceruleus. The RMTg may integrate multiple forebrain and brainstem inputs in relation to a dominant LHb input. Its outputs to neuromodulatory projection systems likely converge with direct LHb projections to those structures. PMID:19235216

  12. Average transverse momentum and energy density in high-energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1986-01-01

    Emulsion chambers were used to measure the transverse momenta of photons or pi(0) mesons produced in high-energy cosmic-ray nucleus-nucleus collisions. A group of events having large average transverse momenta has been found which apparently exceeds the expected limiting values. Analysis of the events at early interaction times, of the order of 1 fm/c, indicates that the observed transverse momentum increases with both rapidity density and energy density.

  13. Results on ultra-relativistic nucleus-nucleus interactions from balloon-borne emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Derrickson, J. H.; Fountain, W.; Meegan, C. A.; Takahashi, Y.; Watts, J. W.; Fuki, M.; Gregory, J. C.; Hayashi, T.

    1985-01-01

    The results of balloon-borne emulsion-chamber measurements on high-energy cosmic-ray nuclei (Burnett et al., 1983) are summarized in tables and graphs and briefly characterized. Special consideration is given to seven nucleus-nucleus interaction events at energy in excess of 1 TeV/A with multiplicity greater than 400, and to Fe interactions (53 with CHO, 10 with emulsion, and 14 with Pb) at 20-60 GeV/A.

  14. Applicability of fluid-dynamical modeling of nucleus-nucleus collisions at relativistic energies

    NASA Astrophysics Data System (ADS)

    Hazineh, Dean; Auvinen, Jussi; Nahrgang, Marlene; Bass, Steffen

    2015-10-01

    At sufficiently high temperatures and densities, similar to the conditions found in the early universe, QCD matter forms a deconfined state called the quark gluon plasma (QGP). This state of matter can be created in collisions of ultra-relativistic heavy-ions, and RHIC data suggests that this QGP behaves similar to an ideal fluid. Viscous relativistic fluid dynamics therefore is one of the preferred theoretical tools to model the time-evolution and properties of the QGP. As the collision energy or the system size is decreased, the range of applicability of viscous fluid dynamics becomes smaller as the length scale of the interaction among the basic constituents is similar to the overall scale of the collision system itself. In order to investigate the validity of fluid-dynamical modeling of proton-nucleus and nucleus-nucleus collisions at LHC and RHIC, we conduct an analysis of the spatial and temporal evolution of the Knudsen number, i.e. the ratio of the microscopic mean free path to the macroscopic length scale of the system. We show results for large and small collision systems, as a function of the specific shear viscosity, and discuss the range of applicability of fluid-dynamical modeling in relativistic proton-nucleus and nucleus-nucleus collisions at different energies.

  15. Nucleus-nucleus total reaction cross sections, and the nuclear interaction radius

    SciTech Connect

    Abu-Ibrahim, Badawy

    2011-04-15

    We study the nucleus-nucleus total reaction cross sections for stable nuclei, in the energy region from 30A MeV to about 1A GeV, and find them to be in proportion to ({radical}({sigma}{sub pp}{sup tot}Z{sub 1}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 1}{sup 2/3})+{radical}({sigma}{sub pp}{sup tot}Z{sub 2}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 2}{sup 2/3})) {sup 2} in the mass range 8 to 100. Also, we find a parameter-free relation that enables us to predict a total reaction cross section for any nucleus-nucleus within 10% uncertainty at most, using the experimental value of the total reaction cross section of a given nucleus-nucleus. The power of the relation is demonstrated by several examples. The energy dependence of the nuclear interaction radius is deduced; it is found to be almost constant in the energy range from about 200A MeV to about 1A GeV; in this energy range and for nuclei with N=Z, R{sub I}(A)=(1.14{+-}0.02)A{sup 1/3} fm.

  16. Amygdala projections to the lateral bed nucleus of the stria terminalis in the Macaque: comparison with ventral striatal afferents

    PubMed Central

    deCampo, Danielle M.; Fudge, Julie L.

    2013-01-01

    The lateral bed nucleus of the stria terminalis (BSTL) is involved in mediating anxiety-related behaviors to sustained aversive stimuli. The BSTL forms part of the central extended amygdala, a continuum composed of the BSTL, the amygdala central nucleus, and cell columns running between the two. The central subdivision (BSTLcn), and the juxtacapsular subdivision (BSTLJ) are two BSTL regions that lie above the anterior commissure, near the ventral striatum. The amygdala, a heterogeneous structure that encodes emotional salience, projects to both the BSTL and ventral striatum. We placed small injections of retrograde tracers into the BSTL, focusing on the BSTLcn and BSTLJ, and analyzed the distribution of labeled cells in amygdala subregions. We compared this to the pattern of labeled cells following injections into the ventral striatum. All retrograde results were confirmed by anterograde studies. We found that the BSTLcn receives stronger amygdala inputs relative to the BSTLJ. Furthermore, the BSTLcn is defined by inputs from the corticoamygdaloid transition area and central nucleus, while the BSTLJ receives inputs mainly from the magnocellular accessory basal and basal nucleus. In the ventral striatum, the dorsomedial shell receives inputs that are similar, but not identical, to inputs to the BSTLcn. In contrast, amygdala projections to the ventral shell/core are similar to projections to the BSTLJ. These findings indicate that the BSTLcn and BSTLJ receive distinct amygdala afferent inputs and that the dorsomedial shell is a transition zone with the BSTLcn, while the ventral shell/core are transition zones with the BSTLJ. PMID:23696521

  17. Centrally administered glucagon stimulates sympathetic nerve activity in rat.

    PubMed

    Krzeski, R; Czyzyk-Krzeska, M F; Trzebski, A; Millhorn, D E

    1989-12-18

    The effect of pancreatic glucagon given intravenously, intracerebroventricularly and microinjected into the nucleus of the solitary tract on sympathetic activity in the cervical trunk and adrenal nerve was examined in rat. In each case glucagon caused a relatively long-lasting substantial increase in discharge of both nerves. This finding shows that glucagon can act centrally to stimulate sympathetic activity. The most probable site for the sympathoexcitatory effect of glucagon is the nucleus of the solitary tract. PMID:2598031

  18. Suprachiasmatic Nucleus Neuropeptides and Their Control of Endogenous Glucose Production.

    PubMed

    Foppen, E; Tan, A A T; Ackermans, M T; Fliers, E; Kalsbeek, A

    2016-04-01

    Defective control of endogenous glucose production is an important factor responsible for hyperglycaemia in the diabetic individual. During the past decade, progressively more evidence has appeared indicating a strong and potentially causal relationship between disturbances of the circadian system and defects of metabolic regulation, including glucose metabolism. The detrimental effects of disturbed circadian rhythms may have their origin in disturbances of the molecular clock mechanisms in peripheral organs, such as the pancreas and liver, or in the central brain clock in the hypothalamic suprachiasmatic nuclei (SCN). To assess the role of SCN output per se on glucose metabolism, we investigated (i) the effect of several SCN neurotransmitters on endogenous glucose production and (ii) the effect of SCN neuronal activity on hepatic and systemic insulin sensitivity. We show that silencing of SCN neuronal activity results in decreased hepatic insulin sensitivity and increased peripheral insulin sensitivity. Furthermore, both oxytocin neurones in the paraventricular nucleus of the hypothalamus (PVN) and orexin neurones in the lateral hypothalamus may be important targets for the SCN control of glucose metabolism. These data further highlight the role of the central clock in the pathophysiology of insulin resistance. PMID:26791158

  19. Functional Heterogeneity in the Bed Nucleus of the Stria Terminalis.

    PubMed

    Gungor, Nur Zeynep; Paré, Denis

    2016-08-01

    Early work stressed the differing involvement of the central amygdala (CeA) and bed nucleus of the stria terminalis (BNST) in the genesis of fear versus anxiety, respectively. In 2009, Walker, Miles, and Davis proposed a model of amygdala-BNST interactions to explain these functional differences. This model became extremely influential and now guides a new wave of studies on the role of BNST in humans. Here, we consider evidence for and against this model, in the process highlighting central principles of BNST organization. This analysis leads us to conclude that BNST's influence is not limited to the generation of anxiety-like responses to diffuse threats, but that it also shapes the impact of discrete threatening stimuli. It is likely that BNST-CeA interactions are involved in modulating responses to such threats. In addition, whereas current views emphasize the contributions of the anterolateral BNST region in anxiety, accumulating data indicate that the anteromedial and anteroventral regions also play a critical role. The presence of multiple functional subregions within the small volume of BNST raises significant technical obstacles for functional imaging studies in humans. PMID:27488624

  20. MOMENTUM DRIVING: WHICH PHYSICAL PROCESSES DOMINATE ACTIVE GALACTIC NUCLEUS FEEDBACK?

    SciTech Connect

    Ostriker, Jeremiah P.; Choi, Ena; Novak, Gregory S.; Ciotti, Luca; Proga, Daniel

    2010-10-10

    The deposition of mechanical feedback from a supermassive black hole (SMBH) in an active galactic nucleus into the surrounding galaxy occurs via broad-line winds which must carry mass and radial momentum as well as energy. The effect can be summarized by the dimensionless parameter {eta}= M-dot{sub outf}/ M-dot{sub acc}=2{epsilon}{sub w}c{sup 2}/v{sub w}{sup 2} where {epsilon}{sub w} ({identical_to} E-dot{sub w}/(M-dot{sub acc}c{sup 2})) is the efficiency with which accreted matter is turned into wind energy in the disk surrounding the central SMBH. The outflowing mass and momentum are proportional to {eta}, and many prior treatments have essentially assumed that {eta} = 0. We perform one- and two-dimensional simulations and find that the growth of the central SMBH is very sensitive to the inclusion of the mass and momentum driving but is insensitive to the assumed mechanical efficiency. For example in representative calculations, the omission of momentum and mass feedback leads to a hundred-fold increase in the mass of the SMBH to over 10{sup 10} M{sub sun}. When allowance is made for momentum driving, the final SMBH mass is much lower and the wind efficiencies that lead to the most observationally acceptable results are relatively low with {epsilon}{sub w} {approx}< 10{sup -4}.

  1. Dropped nucleus following phacoemulsification cataract surgery.

    PubMed

    Tajunisah, I; Reddy, S C

    2007-12-01

    Twenty two cases of dropped nucleus following 1,196 phacoemulsification procedures in cataract surgery were examined retrospectively to determine the incidence, predisposing factors and visual outcomes of this dreaded complication. All the cases underwent pars plana vitrectomy and the lens fragments were removed with phacofragmotome, vitrectomy cutter or delivered through limbus. The incidence of dropped nucleus was 1.84%. The predisposing factors were hard cataracts (13.6%), polar cataracts (9.1%), previously vitrectomized eyes (4.5%) and high myopia (4.5%). The final visual outcome was > or = 6/12 in 10 eyes (45.5%); complications were seen in 5 eyes (22.7%). The interval between initial surgery and vitrectomy, the method of fragment removal and the type of lens implanted, did not influence the final visual outcome. PMID:18705466

  2. Cell Nucleus-Targeting Zwitterionic Carbon Dots

    PubMed Central

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-01-01

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation. PMID:26689549

  3. Macromolecular transport in synapse to nucleus communication.

    PubMed

    Panayotis, Nicolas; Karpova, Anna; Kreutz, Michael R; Fainzilber, Mike

    2015-02-01

    Local signaling events at synapses or axon terminals must be communicated to the nucleus to elicit transcriptional responses. The lengths of neuronal processes pose a significant challenge for such intracellular communication. This challenge is met by mechanisms ranging from rapid signals encoded in calcium waves to slower macromolecular signaling complexes carried by molecular motors. Here we summarize recent findings on macromolecular signaling from the synapse to the nucleus, in comparison to those employed in injury signaling along axons. A number of common themes emerge, including combinatorial signal encoding by post-translational mechanisms such as differential phosphorylation and proteolysis, and conserved roles for importins in coordinating signaling complexes. Neurons may integrate ionic flux with motor-transported signals as a temporal code for synaptic plasticity signaling. PMID:25534890

  4. Coherency in neutrino-nucleus elastic scattering

    NASA Astrophysics Data System (ADS)

    Kerman, S.; Sharma, V.; Deniz, M.; Wong, H. T.; Chen, J.-W.; Li, H. B.; Lin, S. T.; Liu, C.-P.; Yue, Q.; Texono Collaboration

    2016-06-01

    Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter (α ) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold, and target nucleus are studied. The ranges of α that can be probed with realistic neutrino experiments are derived, indicating complementarity between projects with different sources and targets. Uncertainties in nuclear physics and in α would constrain sensitivities in probing physics beyond the standard model. The maximum neutrino ene