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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 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

  17. 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

  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 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

  4. 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

  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 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

  8. 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

  9. 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

  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 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

  17. 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

  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. 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

  3. 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

  4. 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

  5. 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

  6. 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

  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. 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

  12. 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

  13. 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

  14. 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

  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. 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

  20. 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

  1. 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

  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. 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

  17. 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

  18. 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

  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. 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

  2. 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

  3. 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

  4. 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

  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. 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

  7. 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

  8. 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

  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. 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

  18. 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

  19. 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

  20. 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

  1. 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

  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. 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

  7. 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

  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. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  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. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  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. 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

  18. 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

  19. 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

  20. 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

  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. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  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. 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

  17. 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

  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