Contour integration, the linking of collinear but disconnected visual elements across space, is an essential facet of object and scene perception. Here, we set out to arbitrate between two previously advanced mechanisms of contour integration: serial facilitative interactions between collinear cells in the primary visual cortex (V1) versus pooling of inputs in higher-order visual areas. To this end, we used high-density electrophysiological recordings to assess the spatio-temporal dynamics of brain activity in response to Gabor contours embedded in Gabor noise (so-called “pathfinder displays”) versus control stimuli. Special care was taken to elicit and detect early activity stemming from the primary visual cortex, as indexed by the C1 component of the visual evoked potential. Arguing against a purely early V1 account, there was no evidence for contour-related modulations within the C1 timeframe (50-100 msecs). Rather, the earliest effects were observed within the timeframe of the N1 component (160-200 msecs) and inverse source analysis pointed to principle generators in the lateral occipital complex (LOC) within the ventral visual stream. Source anlaysis also suggested that it was only during this relatively late processing period that contextual effects emerged in hierarchically early visual regions (i.e. V1/V2), consistent with a more distributed process involving recurrent feedback/feedforward interactions between LOC and early visual sensory regions. The distribution of effects uncovered here is consistent with pooling of information in higher order cortical areas as the initial step in contour integration, and that this pooling occurs relatively late in processing rather than during the initial sensory-processing period.
Shpaner, Marina; Molholm, Sophie; Forde, Emma-Jane; Foxe, John J.
Early blindness results in occipital cortex neurons responding to a wide range of auditory and tactile stimuli. These changes in tuning properties are accompanied by an extensive reorganization of the occipital cortex that includes alterations in anatomical structure, neurochemical and metabolic pathways. Although it has been established in animal models that neurochemical pathways are heavily affected by early visual deprivation, the effects of blindness on these pathways in humans is still not well characterized. Here, using (1)H magnetic resonance spectroscopy in nine early blind and normally sighted subjects, we find that early blindness is associated with higher levels of creatine, choline and myo-Inositol and indications of lower levels of GABA within the occipital cortex. These results suggest that the cross-modal responses associated with early blindness may, at least in part, be driven by changes within occipital biochemical pathways. PMID:23954804
Weaver, K E; Richards, T L; Saenz, M; Petropoulos, H; Fine, I
Patients with visual object agnosia fail to recognize the identity of visually presented objects despite preserved semantic knowledge. Object agnosia may result from damage to visual cortex lying close to or overlapping with the lateral occipital complex (LOC), a brain region that exhibits selectivity to the shape of visually presented objects. Despite this anatomical overlap the relationship between shape processing in the LOC and shape representations in object agnosia is unknown. We studied a patient with object agnosia following isolated damage to the left occipito-temporal cortex overlapping with the LOC. The patient showed intact processing of object structure, yet often made identification errors that were mainly based on the global visual similarity between objects. Using functional Magnetic Resonance Imaging (fMRI) we found that the damaged as well as the contralateral, structurally intact right LOC failed to show any object-selective fMRI activity, though the latter retained selectivity for faces. Thus, unilateral damage to the left LOC led to a bilateral breakdown of neural responses to a specific stimulus class (objects and artefacts) while preserving the response to a different stimulus class (faces). These findings indicate that representations of structure necessary for the identification of objects crucially rely on bilateral, distributed coding of shape features. PMID:24863251
Ptak, Radek; Lazeyras, François; Di Pietro, Marie; Schnider, Armin; Simon, Stéphane R
Visual deprivation early in life results in occipital cortical responsiveness across a broad range of perceptual and cognitive tasks. In the reorganized occipital cortex of early blind (EB) individuals, the relative lack of specificity for particular sensory stimuli and tasks suggests that attention effects may play a prominent role in these areas. We wished to establish whether occipital cortical areas
Kurt E. Weaver; Alexander A. Stevens
We have previously reported that an early-blind echolocating individual (EB) showed robust occipital activation when he identified distant, silent objects based on echoes from his tongue clicks (Thaler, Arnott, & Goodale, 2011). In the present study we investigated the extent to which echolocation activation in EB's occipital cortex reflected general echolocation processing per se versus feature-specific processing. In the first experiment, echolocation audio sessions were captured with in-ear microphones in an anechoic chamber or hallway alcove as EB produced tongue clicks in front of a concave or flat object covered in aluminum foil or a cotton towel. All eight echolocation sessions (2 shapes×2 surface materials×2 environments) were then randomly presented to him during a sparse-temporal scanning fMRI session. While fMRI contrasts of chamber versus alcove-recorded echolocation stimuli underscored the importance of auditory cortex for extracting echo information, main task comparisons demonstrated a prominent role of occipital cortex in shape-specific echo processing in a manner consistent with latent, multisensory cortical specialization. Specifically, relative to surface composition judgments, shape judgments elicited greater BOLD activity in ventrolateral occipital areas and bilateral occipital pole. A second echolocation experiment involving shape judgments of objects located 20° to the left or right of straight ahead activated more rostral areas of EB's calcarine cortex relative to location judgments of those same objects and, as we previously reported, such calcarine activity was largest when the object was located in contralateral hemispace. Interestingly, other echolocating experts (i.e., a congenitally blind individual in Experiment 1, and a late blind individual in Experiment 2) did not show the same pattern of feature-specific echo-processing calcarine activity as EB, suggesting the possible significance of early visual experience and early echolocation training. Together, our findings indicate that the echolocation activation in EB's occipital cortex is feature-specific, and that these object representations appear to be organized in a topographic manner. PMID:23391560
Arnott, Stephen R; Thaler, Lore; Milne, Jennifer L; Kish, Daniel; Goodale, Melvyn A
Objective We present a unique case of a midline xanthoma of the occipital bone exhibiting atypical imaging characteristics with preserved bone cortex that has not previously been described. Participant This man presented with refractory headaches and suboccipital pain and a mass within the diploe of the occipital bone but with preserved inner and outer cortex of the bone. Magnetic resonance imaging showed a midline, enhancing, and marrow-replacing process in the occipital bone measuring 1.5 cm in anteroposterior (AP) diameter, resulting in mild indentation of the dorsal aspect of the cerebellar vermis. Results The patient underwent a suboccipital craniectomy. Tumor resection was from the foramen magnum to the inion and laterally until normal bone was encountered. The xanthoma was yellowish and bled a moderate amount upon resection. Conclusion An isolated cranial xanthoma with preserved inner and outer bone cortex involving the occipital bone and of midline location has yet to be described. The differential diagnosis of osteoexpansile skull lesion with preserved bone cortex should now include xanthoma. Given the broad spectrum of imaging characteristics exhibited by this unusual diagnosis, surgical intervention is indicated from a diagnostic as well as a therapeutic standpoint.
Broadway, S. Jared; Arnautovic, Kenan I.; Zhang, Yanlong
We have previously shown that some blind individuals can localize sounds more accurately than their sighted counterparts when one ear is obstructed, and that this ability is strongly associated with occipital cortex activity. Given that spectral cues are important for monaurally localizing sounds when one ear is obstructed, and that blind individuals are more sensitive to small spectral differences, we hypothesized that enhanced use of spectral cues via occipital cortex mechanisms could explain the better performance of blind individuals in monaural localization. Using positron-emission tomography (PET), we scanned blind and sighted persons as they discriminated between sounds originating from a single spatial position, but with different spectral profiles that simulated different spatial positions based on head-related transfer functions. We show here that a sub-group of early blind individuals showing superior monaural sound localization abilities performed significantly better than any other group on this spectral discrimination task. For all groups, performance was best for stimuli simulating peripheral positions, consistent with the notion that spectral cues are more helpful for discriminating peripheral sources. PET results showed that all blind groups showed cerebral blood flow increases in the occipital cortex; but this was also the case in the sighted group. A voxel-wise covariation analysis showed that more occipital recruitment was associated with better performance across all blind subjects but not the sighted. An inter-regional covariation analysis showed that the occipital activity in the blind covaried with that of several frontal and parietal regions known for their role in auditory spatial processing. Overall, these results support the notion that the superior ability of a sub-group of early-blind individuals to localize sounds is mediated by their superior ability to use spectral cues, and that this ability is subserved by cortical processing in the occipital cortex.
Voss, Patrice; Lepore, Franco; Gougoux, Frederic; Zatorre, Robert J.
Using functional magnetic resonance imaging (fMRI) in ten early blind humans, we found robust occipital activation during two odor-processing tasks (discrimination or categorization of fruit and flower odors), as well as during control auditory-verbal conditions (discrimination or categorization of fruit and flower names). We also found evidence for reorganization and specialization of the ventral part of the occipital cortex, with dissociation according to stimulus modality: the right fusiform gyrus was most activated during olfactory conditions while part of the left ventral lateral occipital complex showed a preference for auditory-verbal processing. Only little occipital activation was found in sighted subjects, but the same right-olfactory/left-auditory-verbal hemispheric lateralization was found overall in their brain. This difference between the groups was mirrored by superior performance of the blind in various odor-processing tasks. Moreover, the level of right fusiform gyrus activation during the olfactory conditions was highly correlated with individual scores in a variety of odor recognition tests, indicating that the additional occipital activation may play a functional role in odor processing.
Grandin, Cecile B.; Dricot, Laurence; Plaza, Paula; Lerens, Elodie; Rombaux, Philippe; De Volder, Anne G.
BackgroundThe early visual areas have a clear topographic organization, such that adjacent parts of the cortical surface represent distinct yet adjacent parts of the contralateral visual field. We examined whether cortical regions outside occipital cortex show a similar organization.Methodology\\/Principal FindingsThe BOLD responses to discrete visual field locations that varied in both polar angle and eccentricity were measured using two different
Anthony I. Jack; Gaurav H. Patel; Serguei V. Astafiev; Abraham Z. Snyder; Erbil Akbudak; Gordon L. Shulman; Maurizio Corbetta; Nava Rubin
The electrical stimulation of the occipital (OC) or retrosplenial (RSC) cortex produces antinociception in the rat tail-flick and formalin tests. This study examined the antinociceptive effects of stimulating the OC or RSC in a rat model of post-incision pain. The involvement of the anterior pretectal nucleus (APtN) as intermediary for the effect of OC or RSC stimulation was also evaluated
Ana Carolina Rossaneis; Gláucia Melo Reis; Wiliam A. Prado
Contrasting the impact of congenital versus late-onset acquired blindness provides a unique model to probe how experience at different developmental periods shapes the functional organization of the occipital cortex. We used functional magnetic resonance imaging to characterize brain activations of congenitally blind, late-onset blind and two groups of sighted control individuals while they processed either the pitch or the spatial attributes of sounds. Whereas both blind groups recruited occipital regions for sound processing, activity in bilateral cuneus was only apparent in the congenitally blind, highlighting the existence of region-specific critical periods for crossmodal plasticity. Most importantly, the preferential activation of the right dorsal stream (middle occipital gyrus and cuneus) for the spatial processing of sounds was only observed in the congenitally blind. This demonstrates that vision has to be lost during an early sensitive period in order to transfer its functional specialization for space processing toward a non-visual modality. We then used a combination of dynamic causal modelling with Bayesian model selection to demonstrate that auditory-driven activity in primary visual cortex is better explained by direct connections with primary auditory cortex in the congenitally blind whereas it relies more on feedback inputs from parietal regions in the late-onset blind group. Taken together, these results demonstrate the crucial role of the developmental period of visual deprivation in (re)shaping the functional architecture and the connectivity of the occipital cortex. Such findings are clinically important now that a growing number of medical interventions may restore vision after a period of visual deprivation. PMID:23831614
Collignon, Olivier; Dormal, Giulia; Albouy, Geneviève; Vandewalle, Gilles; Voss, Patrice; Phillips, Christophe; Lepore, Franco
Transcranial magnetic stimulation (TMS) of occipital cortex was performed using a magneto-electric stimulator with a maximum output of 2 Tesla in 24 normal volunteers. The identification of trigrams, presented for 14 ms in horizontal or vertical arrays was significantly impaired when the visual stimulus preceded the occipital magnetic shock by 40 to 120 ms. The extent of impairment was related
G. Beckers; V. Hömberg
SUMMARY High-frequency oscillations (HFOs) at ?80 Hz of nonepileptic nature spontaneously emerge from human cerebral cortex. In 10 patients with extra-occipital lobe epilepsy, we compared the spectral-spatial characteristics of HFOs spontaneously arising from the nonepileptic occipital cortex with those of HFOs driven by a visual task as well as epileptogenic HFOs arising from the extra-occipital seizure focus. We identified spontaneous HFOs at ?80 Hz with a mean duration of 330 msec intermittently emerging from the occipital cortex during interictal slow-wave sleep. The spectral frequency band of spontaneous occipital HFOs was similar to that of visually-driven HFOs. Spontaneous occipital HFOs were spatially sparse and confined to smaller areas, whereas visually-driven HFOs involved the larger areas including the more rostral sites. Neither spectral frequency band nor amplitude of spontaneous occipital HFOs significantly differed from those of epileptogenic HFOs. Spontaneous occipital HFOs were strongly locked to the phase of delta activity, but the strength of delta-phase coupling decayed from 1 to 3 Hz. Conversely, epileptogenic extra-occipital HFOs were locked to the phase of delta activity about equally in the range from 1 to 3 Hz. The occipital cortex spontaneously generates physiological HFOs which may stand out on electrocorticography traces as prominently as pathological HFOs arising from elsewhere; this observation should be taken into consideration during presurgical evaluation. Coupling of spontaneous delta and HFOs may increase the understanding of significance of delta-oscillations during slow-wave sleep. Further studies are warranted to determine whether delta-phase coupling distinguishes physiological from pathological HFOs or simply differs across anatomical locations.
Nagasawa, Tetsuro; Juhasz, Csaba; Rothermel, Robert; Hoechstetter, Karsten; Sood, Sandeep; Asano, Eishi
What happens in vision related cortical areas when congenitally blind (CB) individuals orient attention to spatial locations? Previous neuroimaging of sighted individuals has found overlapping activation in a network of frontoparietal areas including frontal eye-fields (FEF), during both overt (with eye movement) and covert (without eye movement) shifts of spatial attention. Since voluntary eye movement planning seems irrelevant in CB, their FEF neurons should be recruited for alternative functions if their attentional role in sighted individuals is only due to eye movement planning. Recent neuroimaging of the blind has also reported activation in medial occipital areas, normally associated with visual processing, during a diverse set of non-visual tasks, but their response to attentional shifts remains poorly understood. Here, we used event-related fMRI to explore FEF and medial occipital areas in CB individuals and sighted controls with eyes closed (SC) performing a covert attention orienting task, using endogenous verbal cues and spatialized auditory targets. We found robust stimulus-locked FEF activation of all CB subjects, similar but stronger than in SC, suggesting that FEF plays a role in endogenous orienting of covert spatial attention even in individuals in whom voluntary eye movements are irrelevant. We also found robust activation in bilateral medial occipital cortex in CB but not in SC subjects. The response decreased below baseline following endogenous verbal cues but increased following auditory targets, suggesting that the medial occipital area in CB does not directly engage during cued orienting of attention but may be recruited for processing of spatialized auditory targets.
Garg, Arun; Schwartz, Daniel; Stevens, Alexander A.
Number processing interacts with space encoding in a wide variety of experimental paradigms. Most intriguingly, the passive viewing of uninformative number symbols can shift visuo-spatial attention to different target locations according to the number magnitude, i.e., small/large numbers facilitate processing of left/right targets, respectively. The brain architecture dedicated to these attention shifts associated with numbers remains unknown. Evoked potential recordings indicate that both early and late stages are involved in this spatio-numerical interaction, but the neuro-functional anatomy needs to be specified. Here we use, for the first time, functional magnetic resonance imaging (fMRI) to investigate attentional orienting following uninformative Arabic digits. We show that BOLD response in occipital visual regions is modulated by the congruency between digit magnitude (small/large) and target side (left/right). Additionally, we report higher BOLD responses following large (8, 9) compared to small (1, 2) digits in two bilateral parietal regions, yielding a significant effect of digit magnitude. We propose and discuss the view that encoding of semantic representations related to number symbols in parietal cortex leads to shifts in visuo-spatial attention and enhances visual processing in the occipital cortex according to number-space congruency rules. PMID:23044279
Goffaux, Valérie; Martin, Romain; Dormal, Giulia; Goebel, Rainer; Schiltz, Christine
Background The neocortex is a highly specialised and complex brain structure, involved in numerous tasks, ranging from processing and interpretation of somatosensory information, to control of motor functions. The normal function linked to distinct neocortical areas might involve control of highly specific gene expression, and in order to identify such regionally enriched genes, we previously analysed the global gene expression in three different cortical regions (frontomedial, temporal and occipital cortex) from the adult rat brain. We identified distinct sets of differentially expressed genes. One of these genes, namely the hypothetical protein LOC689986 (LOC689986), was of particular interest, due to an almost exclusive expression in the temporal cortex. Results Detailed analysis of LOC689986 in the adult rat brain confirmed the expression in confined areas of parieto-temporal cortex, and revealed highly specific expression in layer 4 of the somatosensory cortex, with sharp borders towards the neighbouring motor cortex. In addition, LOC689986 was found to be translated in vivo, and was detected in the somatosensory cortex and in the Purkinje cells of the cerebellar cortex. The protein was present in neuronal dendrites and also in astrocyte cells. Finally, this unique gene is apparently specific for, and highly conserved in, the vertebrate lineage. Conclusions In this study, we have partially characterised the highly conserved LOC689986 gene, which is specific to the vertebrate linage. The gene displays a distinct pattern of expression in layer 4 of the somatosensory cortex, and areas of the parieto-temporal cortex in rodents.
The aim of this study was to measure differences in occipital cortex excitability in migraineurs before and after administration of topiramate. We have previously demonstrated occipital cortex hyperexcitability in migraine using an objective technique of magnetic suppression of perceptual accuracy (MSPA). We hypothesized that a neuromodulator such as topiramate would demonstrate differences in MSPA in migraine compared with baseline. Ten migraine patients were recruited. To assess inhibitory function MSPA was measured using the following protocol. Timed transcranial magnetic stimulation were delivered at interstimulus intervals (ISI) varying from 40 to 190 ms (eight stimulations at each ISI) at 60% stimulus intensity. Subjects were asked to report letters projected at a fixed luminance on the screen. Visual suppression was calculated based on the number of errors the subjects made using automated analysis. This procedure was repeated at a minimum of two different dosages of topiramate when it was titrated for optimal migraine control. The interim dose was that at which an improvement in headache frequency was first observed, and the optimal dose was that at which the patient had a ? 50% reduction in headache frequency, or had reached a 100-mg dose. The mean [standard error (s.e.)] level of letters reported correct at baseline at 100-ms ISI was 91.6 (3.4) compared with 48.5 (6.0) (P = 0.001) at an optimal dose of topiramate. Dose ranged from 50 to 100 mg; the average dose was 75 mg. The interim dose for most patients was 50 mg; the mean (s.e.) percentage of letters reported correct at interim was 75.9 (6.2) compared with baseline (P = 0.01). Mean number of headaches at baseline was 27 per month, compared with eight headaches per month at interim dose and four headaches per month at optimal dose. There was no significant correlation between mean change in frequency of headache and mean change in inhibition from baseline to optimal dose (0.04, P = 0.89). Topiramate modulates occipital cortex excitability in chronic migraine possibly via mechanisms of cortical inhibition. Since there was not a strong correlation between the degree of inhibition and reduction of migraine frequency, it would appear that topiramate did have an independent effect on cortical excitability that was not dependent on reduction in migraine frequency. PMID:19732073
Aurora, S K; Barrodale, P M; Vermaas, A R; Rudra, C B
Over three months of intensive training with a tactile stimulation device, 18 blind and 10 blindfolded seeing subjects improved in their ability to identify geometric figures by touch. Seven blind subjects spontaneously reported 'visual qualia', the subjective sensation of seeing flashes of light congruent with tactile stimuli. In the latter subjects tactile stimulation evoked activation of occipital cortex on electroencephalography (EEG). None of the blind subjects who failed to experience visual qualia, despite identical tactile stimulation training, showed EEG recruitment of occipital cortex. None of the blindfolded seeing humans reported visual-like sensations during tactile stimulation. These findings support the notion that the conscious experience of seeing is linked to the activation of occipital brain regions in people with blindness. Moreover, the findings indicate that provision of visual information can be achieved through non-visual sensory modalities which may help to minimize the disability of blind individuals, affording them some degree of object recognition and navigation aid. PMID:21853098
Ortiz, Tomás; Poch, Joaquín; Santos, Juan M; Requena, Carmen; Martínez, Ana M; Ortiz-Terán, Laura; Turrero, Agustín; Barcia, Juan; Nogales, Ramón; Calvo, Agustín; Martínez, José M; Córdoba, José L; Pascual-Leone, Alvaro
The functional organization of brain activity was investigated by determination of the correlation between evoked (by photic stimulation) activity in the parietal and occipital cortex. Healthy men aged from 20 to 40 years and men of the same age with schi...
K. K. Monakhov, V. B. Strelets
Tactile vision has been approached from a variety of angles using different techniques. So far, a certain kind of object (and text) recognition has been shown, though seeing as such has not been achieved yet, and it remains unclear. Trough repetitive passive tactile stimulation perceptual processing is transferred from temporo-parietal to occipital areas, which affects object recognition. We report the results of passive tactile stimulation, as well as rTMS, applied to a 50 year old left handed blind male with over 97% loss of vision, who suffers from Peter's anomaly and microphthalmia. After 15 weeks of passive tactile stimulation, the subject showed increased activity in occipital areas associated with the development of visual-like perception which remained unchanged after three months without passive tactile stimulation. Inhibitory rTMS over the visual cortex led to noticeable reduction of spatial recognition performance and visual sensations in this subject. Stable changes in occipital cortical activity can be associated with subjective sensations of seeing. Once occipital activation has been achieved, it is necessary for spatial object recognition. Both facts highlight the implication of occipital areas in tactile vision and the cortical plasticity of passive tactile long-term stimulation in people with blindness. PMID:23819463
Ortiz, Tomás; Poch, Joaquín; Santos, Juan M; Martínez, Ana M; Ortiz-Terán, Laura; Requena, Carmen; Barcia, Juan A; de Erausquin, Gabriel A; Pascual-Leone, Alvaro
The lateral occipital complex (LOC) is a set of areas in the human occipito-temporal cortex responding to objects as op- posed to low-level control stimuli. Conventional functional mag- netic resonance imaging (fMRI) analysis methods based on regional averages could not detect signals discriminative of dif- ferent types of objects in this region. Here, we examined fMRI signals using multivariate pattern
Evelyn Eger; John Ashburner; John-dylan Haynes; Raymond J. Dolan; Geraint Rees
In dementia with Lewy bodies (DLB), blood flow tends to be reduced in the occipital cortex. We previously showed elevated activity of the endothelin and angiotensin pathways in Alzheimer's disease (AD). We have measured endothelin-1 (ET-1) level and angiotensin-converting enzyme (ACE) activity in the occipital cortex in DLB and control brains. We also measured vascular endothelial growth factor (VEGF); factor VIII-related antigen (FVIIIRA) to indicate microvessel density; myelin-associated glycoprotein (MAG), a marker of ante-mortem hypoperfusion; total ?-synuclein (?-syn) and ?-synuclein phosphorylated at Ser129 (?-syn-p129). In contrast to findings in AD, ACE activity and ET-1 level were unchanged in DLB compared with controls. VEGF and FVIIIRA levels were, however, significantly lower in DLB. VEGF correlated positively with MAG concentration (in keeping with a relationship between reduction in VEGF and hypoperfusion), and negatively with ?-syn and ?-syn-p129 levels. Both ?-syn and ?-syn-p129 levels increased in human SH-SY5Y neuroblastoma cells after oxygen-glucose deprivation (OGD), and VEGF level was reduced in SH-SY5Y cells overexpressing ?-syn. Taken together, our findings suggest that reduced microvessel density rather than vasoconstriction is responsible for lower occipital blood flow in DLB, and that the loss of microvessels may result from VEGF deficiency, possible secondary to the accumulation of ?-syn. PMID:24521289
Miners, Scott; Moulding, Hayley; de Silva, Rohan; Love, Seth
The effects of postnatal environmental stimulation on the branching patterns of cortical dendrites were measured in rats. Pups were exposed to 4 daily multisensory enrichment sessions from days 10-24, while littermates were maintained in standard conditions. At 25 days of age, the brains were stained using the Golgi-Cox-Sholl method. Camera lucida drawings were made of the basilar dendritic trees from a total of 528 layer-III occipital cortex pyramidal neurons. A highly significant increase was found in number and length of segments from order 1-5 in the neurons from the enriched subjects. PMID:2791261
Venable, N; Fernández, V; Díaz, E; Pinto-Hamuy, T
Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0-130 ms after the onset of the stimulus in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window. PMID:24584900
Tapia, Evelina; Mazzi, Chiara; Savazzi, Silvia; Beck, Diane M
Background The six-layered neocortex of the mammalian brain may appear largely homologous, but is in reality a modular structure of anatomically and functionally distinct areas. However, global gene expression seems to be almost identical across the cerebral cortex and only a few genes have so far been reported to show regional enrichment in specific cortical areas. Results In the present study on adult rat brain, we have corroborated the strikingly similar gene expression among cortical areas. However, differential expression analysis has allowed for the identification of 30, 24 and 11 genes enriched in frontomedial -, temporal- or occipital cortex, respectively. A large proportion of these 65 genes appear to be involved in signal transduction, including the ion channel Fxyd6, the neuropeptide Grp and the nuclear receptor Rorb. We also find that the majority of these genes display increased expression levels around birth and show distinct preferences for certain cortical layers and cell types in rodents. Conclusions Since specific patterns of expression often are linked to equally specialised biological functions, we propose that these cortex sub-region enriched genes are important for proper functioning of the cortical regions in question.
In his pioneering cytoarchitectonic studies of the human brain, Alfred Walter Campbell identified two structurally different areas in the occipital lobes and assigned two different kinds of visual functions to them. The first area, the visuosensory, was essentially on the mesial surface of the calcarine fissure. It was the terminus of nervous impulses generated in the retina and was where simple visual sensations arose. The second area, the visuopsychic, which surrounded or invested the first, was where sensations were interpreted and elaborated into visual perceptions. I argue that Campbell's distinction between the two areas was the starting point for the eventual differentiation of areas V1-V5. After a brief outline of Campbell's early life and education in Australia and of his Scottish medical education and early work as a pathologist at the Lancashire County Lunatic Asylum at Rainhill near Liverpool, I summarise his work on the human brain. In describing the structures he identified in the occipital lobes, I analyse the similarities and differences between them and the related structures identified by Joseph Shaw Bolton. I conclude by proposing some reasons for how that work came to be overshadowed by the later studies of Brodmann and for the more general lack of recognition given Campbell and his work. Those reasons include the effect of the controversies precipitated by Campbell's alliance with Charles Sherrington over the functions of the sensory and motor cortices. PMID:23218905
NINDS Occipital Neuralgia Information Page Table of Contents (click to jump to sections) What is Occipital Neuralgia? Is there any treatment? ... being done? Clinical Trials Organizations What is Occipital Neuralgia? Occipital neuralgia is a distinct type of headache ...
Albinism is a genetic condition associated with abnormalities of the visual system. Defects in melanin production cause underdevelopment of the fovea, reduced retinal cell numbers and abnormal routing of ganglion cell nerve fibres at the optic chiasm. We examined 19 subjects with albinism and 26 control subjects to determine whether retinal abnormalities affect the structure of the visual cortex. Whole-brain,
Elisabeth A. H. Hagen; Gavin C. Houston; Michael B. Hoffmann; Glen Jeffery; Antony B. Morland
Shape is an object property that inherently exists in vision and touch, and is processed in part by the lateral occipital complex (LOC). Recent studies have shown that shape can be artificially coded by sound using sensory substitution algorithms and learned with behavioral training. This finding offers a unique opportunity to test intermodal generalizability of the LOC beyond the sensory modalities in which shape is naturally perceived. Therefore, we investigated the role of the LOC in processing of shape by examining neural activity associated with learning tactile-shape-coded auditory information. Nine blindfolded sighted people learned the tactile-auditory relationship between raised abstract shapes and their corresponding shape-coded sounds over 5 d of training. Using functional magnetic resonance imaging, subjects were scanned before and after training during a task in which they first listened to a shape-coded sound transformation, then touched an embossed shape, and responded whether or not the tactile stimulus matched the auditory stimulus in terms of shape. We found that behavioral scores improved after training and that the LOC was commonly activated during the auditory and tactile conditions both before and after training. However, no significant training-related change was observed in magnitude or size of LOC activity; rather, the auditory cortex and LOC showed strengthened functional connectivity after training. These findings suggest that the LOC is available to different sensory systems for shape processing and that auditory-tactile sensory substitution training leads to neural changes allowing more direct or efficient access to this site by the auditory system. PMID:21613498
Kim, Jung-Kyong; Zatorre, Robert J
Most visual activities, whether reading, driving, or playing video games, require rapid detection and identification of learned patterns defined by arbitrary conjunctions of visual features. Initially, such detection is slow and inefficient, but it can become fast and efficient with training. To determine how the brain learns to process conjunctions of visual features efficiently, we trained participants over eight consecutive days to search for a target defined by an arbitrary conjunction of color and location among distractors with a different conjunction of the same features. During each training session, we measured brain activity with functional magnetic resonance imaging (fMRI). The speed of visual search for feature conjunctions improved dramatically within just a few days. These behavioral improvements were correlated with increased neural responses to the stimuli in visual cortex. This suggests that changes in neural processing in visual cortex contribute to the speeding up of visual feature conjunction search. We find evidence that this effect is driven by an increase in the signal-to-noise ratio (SNR) of the BOLD signal for search targets over distractors. In a control condition where target and distractor identities were exchanged after training, learned search efficiency was abolished, suggesting that the primary improvement was perceptual learning for the search stimuli, not task-learning. Moreover, when participants were retested on the original task after nine months without further training, the acquired changes in behavior and brain activity were still present, showing that this can be an enduring form of learning and neural reorganization. Hum Brain Mapp 35:1201-1211, 2014. © 2013 Wiley Periodicals, Inc. PMID:23418123
Frank, Sebastian M; Reavis, Eric A; Tse, Peter U; Greenlee, Mark W
Brain rhythms are more than just passive phenomena in visual cortex. For the first time, we show that the physiology underlying brain rhythms actively suppresses and releases cortical areas on a second-to-second basis during visual processing. Furthermore, their influence is specific at the scale of individual gyri. We quantified the interaction between broadband spectral change and brain rhythms on a second-to-second basis in electrocorticographic (ECoG) measurement of brain surface potentials in five human subjects during a visual search task. Comparison of visual search epochs with a blank screen baseline revealed changes in the raw potential, the amplitude of rhythmic activity, and in the decoupled broadband spectral amplitude. We present new methods to characterize the intensity and preferred phase of coupling between broadband power and band-limited rhythms, and to estimate the magnitude of rhythm-to-broadband modulation on a trial-by-trial basis. These tools revealed numerous coupling motifs between the phase of low-frequency (?, ?, ?, ?, and ? band) rhythms and the amplitude of broadband spectral change. In the ? and ? ranges, the coupling of phase to broadband change is dynamic during visual processing, decreasing in some occipital areas and increasing in others, in a gyrally specific pattern. Finally, we demonstrate that the rhythms interact with one another across frequency ranges, and across cortical sites. PMID:21119778
Miller, Kai J; Hermes, Dora; Honey, Christopher J; Sharma, Mohit; Rao, Rajesh P N; den Nijs, Marcel; Fetz, Eberhard E; Sejnowski, Terrence J; Hebb, Adam O; Ojemann, Jeffrey G; Makeig, Scott; Leuthardt, Eric C
Occipital pain is a common complaint amongst patients with headache, and the differential can include many primary headache disorders such as cervicogenic headache or migraine. Occipital neuralgia is an uncommon cause of occipital pain characterized by paroxysmal lancinating pain in the distribution of the greater, lesser or third occipital nerves. Greater occipital nerve blockade with anesthetics and/or corticosteroids can aid in confirming the diagnosis and providing pain relief. However, nerve blocks are also effective in migraine headache and misdiagnosis can result in a false positive. Physical therapy and preventive medication with antiepileptics and tricyclic antidepressants are often effective treatments for occipital neuralgia. Refractory cases may require intervention with pulsed radiofrequency or occipital nerve stimulation. PMID:24737457
A genetic deficiency of lysosomal alpha-mannosidase causes the lysosomal storage disease alpha-mannosidosis (AMD), in which oligosaccharide accumulation occurs in neurons and glia. The purpose of this study was to evaluate the role of magnetic resonance spectroscopy (MRS) in detecting the oligosaccharide accumulation in AMD. Five cats with AMD and eight age-matched normal cats underwent in vivo MRS studies with a single voxel short echo time (20 ms) STEAM spectroscopy sequence on a 4.7T magnet. Two voxels were studied in each cat, from the cerebellar vermis and the occipital cortex. Metabolites of brain samples from these regions were extracted with perchloric acid and analyzed by high resolution NMR spectroscopy. A significantly elevated unresolved resonance signal between 3.4 and 4. ppm was observed in the cerebellar vermis and occipital cortex of all AMD cats, which was absent in normal cats. This resonance was shown to be from carbohydrate moieties by high resolution NMR of tissue extracts. Resonances from the Glc-NAc group (1.8-2.2 ppm) along with anomeric proton signals (4.6-5.4 ppm) from undigested oligosaccharides were also observed in the extract spectra from AMD cats. This MRS spectral pattern may be a useful biomarker for AMD diagnosis as well as for assessing responses to therapy. PMID:19743435
Magnitsky, Sergey; Vite, Charles H; Delikatny, Edward J; Pickup, Stephen; Wehrli, Suzanne; Wolfe, John H; Poptani, Harish
A number of MRI studies have shown focal or diffuse cortical gray matter (GM) abnormalities in patients with post-traumatic stress disorder (PTSD). However, the results of these studies are unclear regarding the cortical regions involved in this condition, perhaps due to the heterogeneity of the PTSD population included or to the differences in the methodology used for the quantification of the brain structures. In this study, we assessed differences in cortical GM volumes between a selected group of 25 drug-naive PTSD patients with history of adulthood trauma and 25 matched non-traumatized controls. Analyses were performed by using two different automated methods: the structural image evaluation using normalization of atrophy (SIENAX) and the voxel-based morphometry (VBM), as we trusted that if these complementary techniques provided similar results, it would increase the confidence in the validity of the assessment. Results of SIENAX and VBM analyses similarly showed that cortical GM volume decreases in PTSD patients when compared to healthy controls, particularly in the frontal and occipital lobes. These decreases seem to correlate with clinical measures. Our findings suggest that in drug-naïve PTSD patients with a history of adulthood trauma, brain structural damage is diffuse, with a particular prevalence for the frontal and occipital lobes, and is clinically relevant. PMID:21710131
Tavanti, Maricla; Battaglini, Marco; Borgogni, Federico; Bossini, Letizia; Calossi, Sara; Marino, Daniela; Vatti, Gianpaolo; Pieraccini, Fulvio; Federico, Antonio; Castrogiovanni, Paolo; De Stefano, Nicola
While the relationship between sensory stimulation and tasks and the size of the cortical activations is generally unknown,\\u000a the visual modality offers a unique possibility of an experimental manipulation of stimulus size-related increases of the\\u000a spatial extent of cortical activation even during the earliest activity in the retinotopically organized primary visual cortex.\\u000a We used magnetoecephalography (MEG), visual stimuli of increasing
Sanja Josef Golubic; Ana Susac; Veljko Grilj; Douglas Ranken; Ralph Huonker; Jens Haueisen; Selma Supek
Acceleration (+GZ)-induced loss of consciousness (G LOC) is but one isolated symptom that results when central nervous system (CNS) function is altered by G-stress. Other symptoms and changes also result when reduction of oxygenated blood flow to the CNS ...
J. E. Whinnery
In humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single-unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal cortex, is involved in both components of prehension, the hand transport towards the visual target and the grip formation to secure the grasp. In Experiment 1, neural activity was recorded in V6A while two monkeys performed two instructed-delay reaching tasks (reach-to-point and reach-to-grasp) under controlled conditions in darkness. Fourty-five of 93 tested neurons (48%) were modulated during reach-to-point and 62% (52/84) during reach-to-grasp. In 63% of cells (51/81) neural activity was significantly different between reach-to-point and reach-to-grasp tasks, suggesting that grip formation could influence neural activity. In Experiment 2, two monkeys performed natural reach-to-grasp movements in fully lit environment; V6A neural activity and arm-hand movements were recorded by a digital camcorder and analysed frame-by-frame using a digital video technique. Thirty of the 58 tested neurons (52%) were modulated during natural prehension; about 30% of these neurons (8/30) were modulated only during the last phase of prehension, i.e. during finger flexion around the object to be grasped. This is the first direct demonstration that both reaching and grasping modulate neural activity in the caudal part of the posterior parietal cortex of the macaque. Our work suggests a strict functional homology between human and monkey superior parietal lobule. PMID:15525286
Fattori, Patrizia; Breveglieri, Rossella; Amoroso, Katia; Galletti, Claudio
A new technology of the plastic package is offered in volume production of 16 Mb DRAM. This new package, called the LOC (Lead On Chip) structured package, is characterized by directly bonding the lead frame to the surface of the chip with a adhesive tape. This technology requires some new type packaging materials. Adhesive tape is the key material used
Y. Okugawa; T. Yoshida; T. Suzuki; H. Nakayoshi
There are reports of differences in occipital lobe asymmetry within psychiatric populations when compared with healthy control subjects. Anecdotal evidence and enlarged lateral ventricles suggests that there may also be a different pattern of curvature whereby one occipital lobe wraps around the other, termed 'occipital bending'. We investigated the prevalence of occipital bending in 51 patients with major depressive disorder (males mean age = 41.96 ± 14.00 years, females mean age = 40.71 ± 12.41 years) and 48 age- and sex-matched healthy control subjects (males mean age = 40.29 ± 10.23 years, females mean age = 42.47 ± 14.25 years) and found the prevalence to be three times higher among patients with major depressive disorder (18/51, 35.3%) when compared with control subjects (6/48, 12.5%). The results suggest that occipital bending is more common among patients with major depressive disorder than healthy subjects, and that occipital asymmetry and occipital bending are separate phenomena. Incomplete neural pruning may lead to the cranial space available for brain growth being restricted, or ventricular enlargement may exacerbate the natural occipital curvature patterns, subsequently causing the brain to become squashed and forced to 'wrap' around the other occipital lobe. Although the clinical implications of these results are unclear, they provide an impetus for further research into the relevance of occipital bending in major depression disorder. PMID:24740986
Maller, Jerome J; Thomson, Richard H S; Rosenfeld, Jeffrey V; Anderson, Rodney; Daskalakis, Zafiris J; Fitzgerald, Paul B
Occipital condyle fractures are a rare finding in trauma victims. Bilateral fractures are even more unusual and have typically been reported in autopsy studies. We treated two patients with bilateral occipital condyle fractures who had only minor symptoms. Anderson and Montesano's classification,1 possible cranial nerve palsies, diagnosis, and treatment of this rare fracture are discussed. ImagesFigure 1Figure 2
Schrodel, Markus H.; Kestlmeier, Ralph; Trappe, Anna E.
We used fMRI-informed EEG source-imaging in humans to characterize the dynamics of cortical responses during a disparity-discrimination task. After the onset of a disparity-defined target, decision-related activity was found within an extended cortical network that included several occipital regions of interest (ROIs): V4, V3A, hMT+ and the Lateral Occipital Complex (LOC). By using a response-locked analysis, we were able to determine the timing relationships in this network of ROIs relative to the subject's behavioral response. Choice-related activity appeared first in the V4 ROI almost 200 ms before the button press and then subsequently in the V3A ROI. Modeling of the responses in the V4 ROI suggests that this area provides an early contribution to disparity discrimination. Choice-related responses were also found after the button-press in ROIs V4, V3A, LOC and hMT+. Outside the visual cortex, choice-related activity was found in the frontal and temporal poles before the button-press. By combining the spatial resolution of fMRI-informed EEG source imaging with the ability to sort out neural activity occurring before, during and after the behavioral manifestation of the decision, our study is the first to assign distinct functional roles to the extra-striate ROIs involved in perceptual decisions based on disparity, the primary cue for depth. PMID:24513152
Cottereau, Benoit R; Ales, Justin M; Norcia, Anthony M
Although there is evidence for strong connectivity between the amygdala and the visual cortex and some evidence for reduced occipital lobe gray matter volume in patients with post-traumatic stress disorder (PTSD), few studies have directly examined the effects of PTSD on occipital function. The current study used functional and structural MRI to examine occipital cortex function and structure in male combat veterans with and without PTSD. Left occipital gray matter volume was reduced in PTSD patients relative to the controls and correlated negatively with the severity of PTSD symptoms. Functional activity in the lateral occipital complex to aversive and nonaversive pictures presented in novel and repeated presentations was not altered by PTSD. These findings suggest that PTSD adversely affects occipital lobe volume but not the reactivity of the lateral occipital complex to generally aversive, trauma nonspecific stimuli. PMID:22453299
Chao, Linda L; Lenoci, Maryann; Neylan, Thomas C
The prediction of protein sub-cellular localization is an important step toward elucidating protein function. For each query protein sequence, LocTree2 applies machine learning (profile kernel SVM) to predict the native sub-cellular localization in 18 classes for eukaryotes, in six for bacteria and in three for archaea. The method outputs a score that reflects the reliability of each prediction. LocTree2 has performed on par with or better than any other state-of-the-art method. Here, we report the availability of LocTree3 as a public web server. The server includes the machine learning-based LocTree2 and improves over it through the addition of homology-based inference. Assessed on sequence-unique data, LocTree3 reached an 18-state accuracy Q18 = 80 ± 3% for eukaryotes and a six-state accuracy Q6 = 89 ± 4% for bacteria. The server accepts submissions ranging from single protein sequences to entire proteomes. Response time of the unloaded server is about 90 s for a 300-residue eukaryotic protein and a few hours for an entire eukaryotic proteome not considering the generation of the alignments. For over 1000 entirely sequenced organisms, the predictions are directly available as downloads. The web server is available at http://www.rostlab.org/services/loctree3. PMID:24848019
Goldberg, Tatyana; Hecht, Maximilian; Hamp, Tobias; Karl, Timothy; Yachdav, Guy; Ahmed, Nadeem; Altermann, Uwe; Angerer, Philipp; Ansorge, Sonja; Balasz, Kinga; Bernhofer, Michael; Betz, Alexander; Cizmadija, Laura; Do, Kieu Trinh; Gerke, Julia; Greil, Robert; Joerdens, Vadim; Hastreiter, Maximilian; Hembach, Katharina; Herzog, Max; Kalemanov, Maria; Kluge, Michael; Meier, Alice; Nasir, Hassan; Neumaier, Ulrich; Prade, Verena; Reeb, Jonas; Sorokoumov, Aleksandr; Troshani, Ilira; Vorberg, Susann; Waldraff, Sonja; Zierer, Jonas; Nielsen, Henrik; Rost, Burkhard
Real-world visual scenes are complex cluttered, and heterogeneous stimuli engaging scene- and object-selective cortical regions including parahippocampal place area (PPA), retrosplenial complex (RSC), and lateral occipital complex (LOC). To understand the unique contribution of each region to distributed scene representations, we generated predictions based on a neuroanatomical framework adapted from monkey and tested them using minimal scenes in which we independently manipulated both spatial layout (open, closed, and gradient) and object content (furniture, e.g., bed, dresser). Commensurate with its strong connectivity with posterior parietal cortex, RSC evidenced strong spatial layout information but no object information, and its response was not even modulated by object presence. In contrast, LOC, which lies within the ventral visual pathway, contained strong object information but no background information. Finally, PPA, which is connected with both the dorsal and the ventral visual pathway, showed information about both objects and spatial backgrounds and was sensitive to the presence or absence of either. These results suggest that 1) LOC, PPA, and RSC have distinct representations, emphasizing different aspects of scenes, 2) the specific representations in each region are predictable from their patterns of connectivity, and 3) PPA combines both spatial layout and object information as predicted by connectivity.
Kravitz, Dwight J.; Baker, Chris I.
Real-world visual scenes are complex cluttered, and heterogeneous stimuli engaging scene- and object-selective cortical regions including parahippocampal place area (PPA), retrosplenial complex (RSC), and lateral occipital complex (LOC). To understand the unique contribution of each region to distributed scene representations, we generated predictions based on a neuroanatomical framework adapted from monkey and tested them using minimal scenes in which we independently manipulated both spatial layout (open, closed, and gradient) and object content (furniture, e.g., bed, dresser). Commensurate with its strong connectivity with posterior parietal cortex, RSC evidenced strong spatial layout information but no object information, and its response was not even modulated by object presence. In contrast, LOC, which lies within the ventral visual pathway, contained strong object information but no background information. Finally, PPA, which is connected with both the dorsal and the ventral visual pathway, showed information about both objects and spatial backgrounds and was sensitive to the presence or absence of either. These results suggest that 1) LOC, PPA, and RSC have distinct representations, emphasizing different aspects of scenes, 2) the specific representations in each region are predictable from their patterns of connectivity, and 3) PPA combines both spatial layout and object information as predicted by connectivity. PMID:22473894
Harel, Assaf; Kravitz, Dwight J; Baker, Chris I
What is the neural code for object shape? Despite intensive research, the precise nature of object representations in high-level visual cortex remains elusive. Here we use functional magnetic resonance imaging (fMRI) to show that convex shapes are encoded in a privileged fashion by human lateral occipital complex (LOC), a region that has been implicated in object recognition. On each trial, two convex or two concave shapes that were either identical or different were presented sequentially. Critically, the convex and concave stimuli were the same except for a binocular disparity change that reversed the figure–ground assignment. The fMRI response in LOC for convex stimuli was higher for different than that for identical shape pairs, indicating sensitivity to differences in convex shape. However, when the same stimuli were seen as concave, the response for different and identical pairs was the same, indicating lower sensitivity to changes in concave shape than convex shape. This pattern was more pronounced in the anterior than that in the posterior portion of LOC. These results suggest that convex contours could be important elements in cortical object representations.
Haushofer, Johannes; Baker, Chris I.; Livingstone, Margaret S.; Kanwisher, Nancy
Here we review recent findings that reveal the functional properties of extra-striate regions in the human visual cortex that are involved in the representation and perception of objects. We characterize both the invariant and non-invariant properties of these regions and we discuss the correlation between activation of these regions and recognition. Overall, these results indicate that the lateral occipital complex
Kalanit Grill-Spector; Zoe Kourtzi; Nancy Kanwisher
The anatomic distribution of the greater occipital nerve during its path permits a close relationship with muscular structures, tendons, vessels and bones. The rupture of this relationship can origin its irritation and headache. We describe an uncommon association between an osteolytic lesion on occipital bone and greater occipital nerve. The patient, female 50, has been presenting headache for two years on the right occipital region spreading to the hemicranic and ipsilateral supraorbital region. The symptoms started spontaneously or by pressure on the trapezius tendon. The pain lasted about 30 minutes, compressive, mild intensity, with no autonomic symptoms and no improvement after the infiltration in the greater occipital nerve. The total improvement of the symptoms after releasing the nerve has allowed us to associate this lesion to the presence of algic symptoms. PMID:10347737
Piovesan, E J; Werneck, L C; Kowacs, P A; Tatsui, C; Lange, M C; Carraro Júnior, H; Wittig, E O
The invariant properties of human cortical neurons cannot be studied directly by fMRI due to its limited spatial resolution. Here, we circumvented this limitation by using fMR adaptation, namely, reduction of the fMR signal due to repeated presentation of identical images. Object-selective regions (lateral occipital complex [LOC]) showed a monotonic signal decrease as repetition frequency increased. The invariant properties of
Kalanit Grill-Spector; Tammar Kushnir; Shimon Edelman; Galia Avidan; Yacov Itzchak; Rafael Malach
High-level visual cortex in humans includes functionally defined regions that preferentially respond to objects, faces and places. It is unknown how these regions develop and whether their development relates to recognition memory. We used functional magnetic resonance imaging to examine the development of several functionally defined regions including object (lateral occipital complex, LOC)-, face (‘fusiform face area’, FFA; superior temporal sulcus, STS)- and place (‘parahippocampal place area’, PPA)-selective cortices in children (ages 7–11), adolescents (12–16) and adults. Right FFA and left PPA volumes were substantially larger in adults than in children. This development occurred by expansion of FFA and PPA into surrounding cortex and was correlated with improved recognition memory for faces and places, respectively. In contrast, LOC and STS volumes and object-recognition memory remained constant across ages. Thus, the ventral stream undergoes a prolonged maturation that varies temporally across functional regions, is determined by brain region rather than stimulus category, and is correlated with the development of category-specific recognition memory.
Golarai, Golijeh; Ghahremani, Dara G; Whitfield-Gabrieli, S; Reiss, Allan; Eberhardt, Jennifer L; Gabrieli, John DE; Grill-Spector, Kalanit
...2009-10-01 false Revocation of the LOC. 732.406-74 Section 732.406-74...Payments 732.406-74 Revocation of the LOC. If during the term of the contract FM/CMP believes that the LOC should be revoked, FM/CMP may,...
...2010-10-01 false Revocation of the LOC. 732.406-74 Section 732.406-74...Payments 732.406-74 Revocation of the LOC. If during the term of the contract FM/CMP believes that the LOC should be revoked, FM/CMP may,...
... 2009-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under subsection...
... 2010-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under subsection...
... 2009-10-01 2009-10-01 false LOC contract clause. 732.406-73 Section...FINANCING Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain the clause...
... 2010-10-01 2010-10-01 false LOC contract clause. 732.406-73 Section...FINANCING Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain the clause...
One hundred thirty-four cases of occipital skull fracture seen over the past 15 years at the Medical Center Hospital of Vermont have been analyzed with respect to their clinical course and neurologic outcome. Among the cases reviewed, one third of patients had an uncomplicated course, 24% recovered with mild neurologic findings (such as cranial nerve palsy), and 13% died as a result of neurologic insult. This high morbidity results from combinations of traumatic subarachnoid hemorrhage, coup and contrecoup brain lesions, and injury at the skull base. Posterior fossa hematoma, cerebellar contusion, parietal and occipital lobe injury, and cranial nerve injuries associated with this lesion are discussed in detail. CAT scanning is now part of our diagnostic routine in patients with occipital fracture in coma grades 1-5 (Grady scale). PMID:7143497
Young, H A; Schmidek, H H
Epileptic seizures of parietal and occipital origin are heterogeneous and mainly characterised by the presenting auras, although the most dramatic clinical manifestations may reflect spread, and overshadow the focal origin. The two lobes serve mainly sensory functions, and the characteristic seizure phenomena are therefore subjective sensations. The incidence of these seizures is not well known, but they are generally considered
JOHN S. DUNCAN
Functional magnetic resonance imaging (fMRI) has revealed a set of regions selectively engaged in visual scene processing: the parahippocampal place area (PPA); the retrosplenial complex (RSC); and a region around the transverse occipital sulcus (previously known as “TOS”), here renamed the “occipital place area” (OPA). Are these regions not only preferentially activated by, but also causally involved in scene perception? Although past neuropsychological data imply a causal role in scene processing for PPA and RSC, no such evidence exists for OPA. Thus, to test the causal role of OPA in human adults, we delivered transcranial magnetic stimulation (TMS) to the right OPA (rOPA) or the nearby face-selective right occipital face area (rOFA) while participants performed fine-grained perceptual discrimination tasks on scenes or faces. TMS over rOPA impaired discrimination of scenes but not faces, while TMS over rOFA impaired discrimination of faces but not scenes. In a second experiment, we delivered TMS to rOPA, or the object-selective right lateral occipital complex (rLOC) while participants performed categorization tasks involving scenes and objects. TMS over rOPA impaired categorization accuracy of scenes but not objects, while TMS over rLOC impaired categorization accuracy of objects but not scenes. These findings provide the first evidence that OPA is causally involved in scene processing, and further show that this causal role is selective for scene perception. Our findings illuminate the functional architecture of the scene perception system, and also argue against the “distributed coding” view in which each category-selective region participates in the representation of all objects.
Dilks, Daniel D.; Julian, Joshua B.; Paunov, Alexander M.; Kanwisher, Nancy
Functional magnetic resonance imaging has revealed a set of regions selectively engaged in visual scene processing: the parahippocampal place area (PPA), the retrosplenial complex (RSC), and a region around the transverse occipital sulcus (previously known as "TOS"), here renamed the "occipital place area" (OPA). Are these regions not only preferentially activated by, but also causally involved in scene perception? Although past neuropsychological data imply a causal role in scene processing for PPA and RSC, no such evidence exists for OPA. Thus, to test the causal role of OPA in human adults, we delivered transcranial magnetic stimulation (TMS) to the right OPA (rOPA) or the nearby face-selective right occipital face area (rOFA) while participants performed fine-grained perceptual discrimination tasks on scenes or faces. TMS over rOPA impaired discrimination of scenes but not faces, while TMS over rOFA impaired discrimination of faces but not scenes. In a second experiment, we delivered TMS to rOPA, or the object-selective right lateral occipital complex (rLOC), while participants performed categorization tasks involving scenes and objects. TMS over rOPA impaired categorization accuracy of scenes but not objects, while TMS over rLOC impaired categorization accuracy of objects but not scenes. These findings provide the first evidence that OPA is causally involved in scene processing, and further show that this causal role is selective for scene perception. Our findings illuminate the functional architecture of the scene perception system, and also argue against the "distributed coding" view in which each category-selective region participates in the representation of all objects. PMID:23345209
Dilks, Daniel D; Julian, Joshua B; Paunov, Alexander M; Kanwisher, Nancy
LOC79017 (MW 21.0 kDa, residues 1-188) was annotated as a hypothetical protein encoded by Homo sapiens chromosome 7 open reading frame 24. It was selected as a target by the Center for Eukaryotic Structural Genomics (CESG) because it did not share more than 30% sequence identity with any protein for which the three-dimensional structure is known. The biological function of the protein has not been established yet. Parts of LOC79017 were identified as members of uncharacterized Pfam families (residues 1-95 as PB006073 and residues 104-180 as PB031696). BLAST searches revealed homologues of LOC79017 in many eukaryotes, but none of them have been functionally characterized. Here, we report the crystal structure of H. sapiens protein LOC79017 (UniGene code Hs.530024, UniProt code O75223, CESG target number go.35223).
Bae, Euiyoung; Bingman, Craig A.; Aceti, David J.; Phillips, Jr., George N. (UW)
This report presents the results of Loss-of-Coolant (LOC) Test LOC-6, conducted in the Power Burst Facility at the Idaho National Engineering Laboratory by EG and G Idaho, Inc., for the US Nuclear Regulatory Commission. Postirradiation examination results are included, together with the results of thermal-hydraulic and fuel behavior calculations using the RELAP4 and FRAP-T6\\/BALON-2 computer codes. Two of the four
T. M. Broughton; K. Vinjamuri; D. L. Hagrman; D. W. Golden; P. E. MacDonald
Functional magnetic resonance imaging (MRI) showed that the superior temporal and occipital cortex are involved in multisensory integration. Probabilistic fiber tracking based on diffusion-weighted MRI suggests that multisensory processing is supported by white matter connections between auditory cortex and the temporal and occipital lobe. Here, we present a combined functional MRI and probabilistic fiber tracking study that reveals multisensory processing mechanisms that remained undetected by either technique alone. Ten healthy participants passively observed visually presented lip or body movements, heard speech or body action sounds, or were exposed to a combination of both. Bimodal stimulation engaged a temporal-occipital brain network including the multisensory superior temporal sulcus (msSTS), the lateral superior temporal gyrus (lSTG), and the extrastriate body area (EBA). A region-of-interest (ROI) analysis showed multisensory interactions (e.g., subadditive responses to bimodal compared to unimodal stimuli) in the msSTS, the lSTG, and the EBA region. Moreover, sounds elicited responses in the medial occipital cortex. Probabilistic tracking revealed white matter tracts between the auditory cortex and the medial occipital cortex, the inferior occipital cortex (IOC), and the superior temporal sulcus (STS). However, STS terminations of auditory cortex tracts showed limited overlap with the msSTS region. Instead, msSTS was connected to primary sensory regions via intermediate nodes in the temporal and occipital cortex. Similarly, the lSTG and EBA regions showed limited direct white matter connections but instead were connected via intermediate nodes. Our results suggest that multisensory processing in the STS is mediated by separate brain areas that form a distinct network in the lateral temporal and inferior occipital cortex.
Beer, Anton L.; Plank, Tina; Meyer, Georg; Greenlee, Mark W.
A case of a Chiari malformation with an extraordinarily thick occipital bone is described. The thick occipital bone might make the posterior fossa narrow with consequent herniation of the cerebellar tonsils to the foramen magnum and formation of a syrinx. At dural plasty, well-developed marginal and occipital sinuses should be deliberately handled with the preservation of normal venous drainage. This case gives us the essence of the occurrence mechanisms of Chiari malformation and foramen magnum decompression. PMID:21339798
Yasuhara, Takao; Miyoshi, Yasuyuki; Date, Isao
The occipital lobe contains retinotopic representations of the visual field. The representation of the central retina in early visual areas (V1–3) is found at the occipital pole. When the central retina is lesioned in both eyes by macular degeneration, this region of visual cortex at the occipital pole is accordingly deprived of input. However, even when such lesions occur in
Heidi A Baseler; André Gouws; Koen V Haak; Christopher Racey; Michael D Crossland; Adnan Tufail; Gary S Rubin; Frans W Cornelissen; Antony B Morland
Two types of childhood epilepsy have recently been reported: childhood epilepsy with occipital paroxysms, and benign nocturnal childhood occipital epilepsy. This article reports the clinical evolution, electroencephalographic (EEG) changes, and response to therapy of eight children with childhood epilepsy with occipital paroxysms (five boys and three girls, aged from 11\\/12 to 8 years) and eight children with benign nocturnal childhood
Alberto Verrotti; Sergio Domizio; Maria Guerra; Giuseppe Sabatino; Guido Morgese; Francesco Chiarelli
Diffusion tensor imaging (DTI) and fiber tracking (FT) were used to measure the occipital lobe fiber tracts connecting the two hemispheres in individual human subjects. These tracts are important for normal vision. Also, damage to portions of these tracts is associated with alexia. To assess the reliability of the DTI-FT measurements, occipital-callosal projections were estimated from each subject's left and right hemispheres independently. The left and right estimates converged onto the same positions within the splenium. We further characterized the properties of the estimated occipital-callosal fiber tracts by combining them with functional MRI. We used functional MRI to identify visual field maps in cortex and labeled fibers by the cortical functional response at the fiber endpoint. This labeling reveals a regular organization of the fibers within the splenium. The dorsal visual maps (dorsal V3, V3A, V3B, V7) send projections through a large band in the middle of the splenium, whereas ventral visual maps (ventral V3, V4) send projections through the inferior-anterior corner of the splenium. The agreement between the independent left/right estimates, further supported by previous descriptions of homologous tracts in macaque, validates the DTI-FT methods. However, a principal limitation of these methods is low sensitivity: a large number of fiber tracts that connect homotopic regions of ventral and lateral visual cortex were undetected. We conclude that most of the estimated tracts are real and can be localized with a precision of 1-2 mm, but many tracts are missed because of data and algorithm limitations.
Dougherty, Robert F.; Ben-Shachar, Michal; Bammer, Roland; Brewer, Alyssa A.; Wandell, Brian A.
The occipital and frontal lobes are anatomically distant yet functionally highly integrated to generate some of the most complex behaviour. A series of long associative fibres, such as the fronto-occipital networks, mediate this integration via rapid feed-forward propagation of visual input to anterior frontal regions and direct top-down modulation of early visual processing. Despite the vast number of anatomical investigations a general consensus on the anatomy of fronto-occipital connections is not forthcoming. For example, in the monkey the existence of a human equivalent of the 'inferior fronto-occipital fasciculus' (iFOF) has not been demonstrated. Conversely, a 'superior fronto-occipital fasciculus' (sFOF), also referred to as 'subcallosal bundle' by some authors, is reported in monkey axonal tracing studies but not in human dissections. In this study our aim is twofold. First, we use diffusion tractography to delineate the in vivo anatomy of the sFOF and the iFOF in 30 healthy subjects and three acallosal brains. Second, we provide a comprehensive review of the post-mortem and neuroimaging studies of the fronto-occipital connections published over the last two centuries, together with the first integral translation of Onufrowicz's original description of a human fronto-occipital fasciculus (1887) and Muratoff's report of the 'subcallosal bundle' in animals (1893). Our tractography dissections suggest that in the human brain (i) the iFOF is a bilateral association pathway connecting ventro-medial occipital cortex to orbital and polar frontal cortex, (ii) the sFOF overlaps with branches of the superior longitudinal fasciculus (SLF) and probably represents an 'occipital extension' of the SLF, (iii) the subcallosal bundle of Muratoff is probably a complex tract encompassing ascending thalamo-frontal and descending fronto-caudate connections and is therefore a projection rather than an associative tract. In conclusion, our experimental findings and review of the literature suggest that a ventral pathway in humans, namely the iFOF, mediates a direct communication between occipital and frontal lobes. Whether the iFOF represents a unique human pathway awaits further ad hoc investigations in animals. PMID:23137651
Forkel, Stephanie J; Thiebaut de Schotten, Michel; Kawadler, Jamie M; Dell'Acqua, Flavio; Danek, Adrian; Catani, Marco
Controversy surrounds the proposal that specific human cortical regions in the ventral occipitotemporal cortex, commonly called the fusiform face area (FFA) and occipital face area (OFA), are specialized for face processing. Here, we present findings from an fMRI study of identity discrimination of faces and objects that demonstrates the FFA and OFA are equally responsive to processing stimuli at the level of individuals (i.e., individuation), be they human faces or non-face objects. The FFA and OFA were defined via a passive viewing task as regions that produced greater activation to faces relative to non-face stimuli within the middle fusiform gyrus and inferior occipital gyrus. In the individuation task, participants judged whether sequentially presented images of faces, diverse objects, or wristwatches depicted the identical or a different exemplar. All three stimulus types produced equivalent BOLD activation within the FFA and OFA; that is, there was no face-specific or face-preferential processing. Critically, individuation processing did not eliminate an object superiority effect relative to faces within a region more closely linked to object processing in the lateral occipital complex (LOC), suggesting that individuation processes are reasonably specific to the FFA and OFA. Taken together, these findings challenge the prevailing view that the FFA and OFA are face-specific processing regions, demonstrating instead that they function to individuate – i.e., identify specific individuals – within a category. These findings have significant implications for understanding the function of brain regions widely believed to play an important role in social cognition.
Haist, Frank; Lee, Kang; Stiles, Joan
Analyzes differences in students' performance on algorithmic, lower-order cognitive skills (LOCS), and conceptual exam questions and the correlations between their achievements on these categories across different populations.Reports that the highest scores were obtained for the algorithmic questions, the lowest for the conceptual questions, and…
Zoller, Uri; And Others
We present a 45 year old female with right occipital condylar metastases who was treated at William Beaumont Hospital in the Gamma Knife Unit. Clinical results at 17 months follow-up and MRI are exposed. PMID:19776003
Krishnamurthy, Satish; Navarro-Martín, Arturo; Maitz, Ann
Extensive research on the neuropsychology of the parietal and occipital epilepsies has not yet been undertaken. The parietal\\u000a lobes are known to be important for aspects of attention, spatial processing, spoken and written language, coordinated motor\\u000a sequencing, and sensory function. The occipital lobes are known to be involved in visual processing. Although the clinical\\u000a phenomena associated with seizures arising in
Mary Lou Smith; Rebecca L. Billingsley
Congenital occipital dermal sinus with an underlying dermoid is a rare, benign lesion of embryological origin and may occur anywhere along the neuraxis. We present a case of a 15-year-old girl with a vermian dermoid and an occipital dermal sinus. Gross total resection of the lesion was done and post-operative period was uneventful. A detailed review of the literature is also covered.
Srikantha, Umesh; Khanapure, Kiran; Nirmala, S; Varma, Ravi Gopal
Two types of childhood epilepsy have recently been reported: childhood epilepsy with occipital paroxysms, and benign nocturnal childhood occipital epilepsy. This article reports the clinical evolution, electroencephalographic (EEG) changes, and response to therapy of eight children with childhood epilepsy with occipital paroxysms (five boys and three girls, aged from 1 1/12 to 8 years) and eight children with benign nocturnal childhood occipital epilepsy (six boys and two girls, aged from 1 4/12 to 8 3/12 years). A careful clinical and EEG follow-up of at least 7 years was carried out for all patients. At the end of follow-up, all but one of the patients with childhood epilepsy with occipital paroxysms were seizure-free, and only two were still receiving anticonvulsant drugs. All but three children had a normal EEG, and normal mental development was observed in all but two cases. Patients with benign nocturnal childhood occipital epilepsy had a good long-term prognosis; all but two children with benign nocturnal childhood occipital epilepsy had a normal EEG. These two patients showed learning disabilities and poor school performances, and required remedial education. Therefore, although childhood epilepsy with occipital paroxysms and benign nocturnal childhood occipital epilepsy are two different types of epilepsy, the long-term prognosis seems to be similar. PMID:10805186
Verrotti, A; Domizio, S; Guerra, M; Sabatino, G; Morgese, G; Chiarelli, F
... 2009-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...
... 2010-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...
Photic driving using a flashing strobe light was recorded via intracranial electrodes in two patients with occipital epilepsy being evaluated for surgery. The same technique was used to monitor the visual cortex intraoperatively. Visual evoked potentials (VEPs) were also obtained using the intracranial electrodes in one patient. Preoperative photic driving occurred in a separate location from the cortical areas producing ictal epileptiform activity. VEPs were located in the same site as photic driving. Photic driving was monitored throughout the resection and remained unaffected at the end of each procedure. Postoperative visual field testing in both patients showed preservation of central vision although some reduction in peripheral fields was seen. Intraoperative monitoring of the visual cortex using photic stimulation proved to be a reliable technique for preserving central vision during occipital lobe surgery. PMID:10833622
Curatolo, J M; Macdonell, R A; Berkovic, S F; Fabinyi, G C
Occipital condyle fractures are rare, and conservative treatment is sufficient for many cases. Surgical treatment may be required if the condyle fracture is accompanied by atlantooccipital dislocation. Unfortunately, condyle fracture generally cannot be diagnosed with X-ray in the emergency department. Recently, computed tomography scans have been used more frequently, and enable easier diagnosis of these types of fractures. In this report, we describe a patient who admitted to our emergency department after a major trauma. She complained of neck pain, and maxillofacial trauma was more evident. Her cervical X-rays were normal, but cervical computed tomography revealed unilateral occipital condyle fracture. PMID:24936848
Dinç, Cem; Türko?lu, Mehmet Erhan; Tuncer, Cengiz; Aykanat, Omer; Ozçelik, Derya; Ozkan, Gamze
Disruption or embryologic derailment of the normal bony architecture of the craniovertebral junction (CVJ) may result in symptoms. As studies of the embryology and pathology of hypoplasia of the occipital condyles and third occipital condyles are lacking in the literature, the present review was performed. Standard search engines were accessed and queried for publications regarding hypoplastic occipital condyles and third occipital condyles. The literature supports the notion that occipital condyle hypoplasia and a third occipital condyle are due to malformation or persistence of the proatlas, respectively. The Pax-1 gene is most likely involved in this process. Clinically, condylar hypoplasia may narrow the foramen magnum and lead to lateral medullary compression. Additionally, this maldevelopment can result in transient vertebral artery compression secondary to posterior subluxation of the occiput. Third occipital condyles have been associated with cervical canal stenosis, hypoplasia of the dens, transverse ligament laxity, and atlanto-axial instability causing acute and chronic spinal cord compression. Treatment goals are focused on craniovertebral stability. A better understanding of the embryology and pathology related to CVJ anomalies is useful to the clinician treating patients presenting with these entities. PMID:23338989
Tubbs, R Shane; Lingo, Patrick Ryan; Mortazavi, Martin M; Cohen-Gadol, Aaron A
The case of a neonate with a dermoid cyst originating within an occipital encephalocele is reported. The finding of the tumor was made during the routine repair of the meningoencephalocele. To our knowledge this is the first time that this association has been described. (J Child Neurol 1992;7:427-430).
Juan F. Martinez-Lage; Máximo Poza; José Ramos; Maria J. Almagro; Manuel Sempere; José Mestre
Cluster headache is perhaps the most painful of the primary headache disorders. Its treatment includes acute, transitional, and preventive therapy. Despite the availability of many treatments, cluster headache patients can still be difficult to treat. We treated 14 cluster headache patients with greater occipital nerve block as transitional therapy (treatment initiated at the same time as preventive therapy). The mean
M FP Peres; M A Stiles; H C Siow; T D Rozen; W B Young; S D Silberstein
OBJECTIVES—Autistic disorder is a developmental handicap with an unknown neurological basis. Current neuropsychological models for autism suggest an abnormal construction of visual perceptual representation or a deficit in executive functions. These models predict cerebral lesions in the temporo-occipital or frontal regions of autistic patients. The present study aimed at studying the presence of symptoms of autism and visual agnosia in a 13 year old girl who had a right temporo-occipital cortical dysplasia that was surgically removed at the age of 7.?METHODS—Neuropsychological evaluation included Wechsler and Kaufman intelligence scales, a test of word fluency, digit span, Corsi block, California verbal learning, Trail making, Benton facial recognition, Snoodgrass object recognition tests, Rivermead face learning subtest, and developmental test of visual perception. The ADI-R was used to show current and retrospective diagnosis of autistic disorder. Neuroimagery included brain MRI, single photon emission computed tomography (SPECT), and PET.?RESULTS—Brain MRI showed a right occipital defect and an abnormal hyperintensity of the right temporal cortex. PET and SPECT disclosed a left frontal hypometabolism together with the right occipital defect. Neuropsychological testing showed a visual apperceptive agnosia and executive function deficits. Psychiatric study confirmed the diagnosis of autistic disorder.?CONCLUSIONS—Although the possibilty that autism and visual agnosia were dissociable factors in this patient cannot be excluded, the finding of both deficits supports the possibility that occipito-temporal lesions can predispose to the development of autism.??
Jambaque, I; Mottron, L; Ponsot, G; Chiron, C
The recreational drug MDMA (3,4, methylenedioxymethamphetamine; sold under the street name of Ecstasy) is toxic to serotonergic axons in some animal models of MDMA administration. In humans, MDMA use is associated with alterations in markers of brain function that are pronounced in occipital cortex. Among neuroimaging methods, magnetic resonance spectroscopy (MRS) studies of brain metabolites N-acetylaspartate (NAA) and myoinositol (MI) at a field strength of 1.5 Tesla (T) reveal inconsistent results in MDMA users. Because higher field strength proton MRS has theoretical advantages over lower field strengths, we used proton MRS at 4.0 T to study absolute concentrations of occipital cortical NAA and MI in a cohort of moderate MDMA users (n = 9) versus non-MDMA using (n = 7) controls. Mean NAA in non-MDMA users was 10.47 mM (± 2.51), versus 9.83 mM (± 1.94) in MDMA users. Mean MI in non-MDMA users was 7.43 mM (± 1.68), versus 6.57 mM (± 1.59) in MDMA users. There were no statistical differences in absolute metabolite levels for NAA and MI in occipital cortex of MDMA users and controls. These findings are not supportive of MDMA-induced alterations in NAA or MI levels in this small sample of moderate MDMA users. Limitations to this study suggest caution in the interpretation of these results.
Cowan, Ronald L.; Bolo, Nicolas R.; Dietrich, Mary; Haga, Erica; Lukas, Scott E.; Renshaw, Perry F.
We describe a first trimester female foetus with aplasia of the occipital bone allowing a meningocele without skin coverage to be formed. The pregnancy was terminated, and on later autopsy the brain appeared to be intact. The foetus carried an apparently balanced translocation 46,XX,t(3;9)(p21.3;q22.3) inherited from a normal father and grandfather.
Torbjørn M Eggebø; Janne Brathetland; Hege U Dirdal; Gunnar Houge
Long-term Vipassana meditators sat in meditation vs. a control rest (mind-wandering) state for 21 min in a counterbalanced design with spontaneous EEG recorded. Meditation state dynamics were measured with spectral decomposition of the last 6 min of the eyes-closed silent meditation compared to control state. Meditation was associated with a decrease in frontal delta (1-4 Hz) power, especially pronounced in those participants not reporting drowsiness during meditation. Relative increase in frontal theta (4-8 Hz) power was observed during meditation, as well as significantly increased parieto-occipital gamma (35-45 Hz) power, but no other state effects were found for the theta (4-8 Hz), alpha (8-12 Hz), or beta (12-25 Hz) bands. Alpha power was sensitive to condition order, and more experienced meditators exhibited no tendency toward enhanced alpha during meditation relative to the control task. All participants tended to exhibit decreased alpha in association with reported drowsiness. Cross-experimental session occipital gamma power was the greatest in meditators with a daily practice of 10+ years, and the meditation-related gamma power increase was similarly the strongest in such advanced practitioners. The findings suggest that long-term Vipassana meditation contributes to increased occipital gamma power related to long-term meditational expertise and enhanced sensory awareness. PMID:20013298
Cahn, B Rael; Delorme, Arnaud; Polich, John
Mirror focus is one of the evidence of progression in epilepsy, and also has practical points for curative resective epilepsy surgery. The mirror foci are related to the kindling phenomena that occur through interhemispheric callosal or commissural connections. A mirror focus means the secondary epileptogenic foci develop in the contralateral hemispheric homotopic area. Thus mirror foci are mostly reported in patients with temporal or frontal lobe epilepsy, but not in occipital lobe epilepsy. We have observed occipital lobe epilepsy with mirror focus. Before epilepsy surgery, the subject’s seizure onset zone was observed in the left occipital area by ictal studies. Her seizures abated for 10 months after the resection of left occipital epileptogenic focus, but recurred then. The recurred seizures were originated from the right occipital area which was in the homotopic contralateral area. This case can be an evidence that occipital lobe epilepsy may have mirror foci, even though each occipital lobe has any direct interhemispheric callosal connections between them.
Kim, Jiyoung; Shin, Hae kyung; Hwang, Kyoung Jin; Choi, Su Jung; Joo, Eun Yeon; Hong, Seung Bong; Hong, Seung Chul; Seo, Dae-Won
Playing video games is a popular leisure activity among children and adults, and may therefore potentially influence brain structure. We have previously shown a positive association between probability of gray matter (GM) volume in the ventral striatum and frequent video gaming in adolescence. Here we set out to investigate structural correlates of video gaming in adulthood, as the effects observed in adolescents may reflect only a fraction of the potential neural long-term effects seen in adults. On magnetic resonance imaging (MRI) scans of 62 male adults, we computed voxel-based morphometry to explore the correlation of GM with the lifetime amount of video gaming (termed joystick years). We found a significant positive association between GM in bilateral parahippocamal region (entorhinal cortex) and left occipital cortex/inferior parietal lobe and joystick years (P<0.001, corrected for multiple comparisons). An exploratory analysis showed that the entorhinal GM volume can be predicted by the video game genres played, such as logic/puzzle games and platform games contributing positively, and action-based role-playing games contributing negatively. Furthermore, joystick years were positively correlated with hippocampus volume. The association of lifetime amount of video game playing with bilateral entorhinal cortex, hippocampal and occipital GM volume could reflect adaptive neural plasticity related to navigation and visual attention. PMID:23958958
Kühn, S; Gallinat, J
Acceleration (+Gz) induced loss of consciousness (G-LOC) during high +Gz flight maneuvers continues to be a hazard for pilots of high performance aircraft. In the centrifuge studies, G-LOC detection of pilots flying under high +Gz forces is usually made by an observer outside of the gondola and therefore depends upon the reaction time and the alertness of the individual who
Yeu-Shyr Wu; Hun H. Sun; Joseph P. Cammarota; Leonid Hrebien
Protein-coding genes account for only a small part of the human genome, whereas the vast majority of transcripts make up the non-coding RNAs including long non-coding RNAs (lncRNAs). Accumulating evidence indicates that lncRNAs could play a critical role in regulation of cellular processes such as cell growth and apoptosis as well as cancer progression and metastasis. LncRNA loc285194 was previously shown to be within a tumor suppressor unit in osteosarcoma and to suppress tumor cell growth. However, it is unknown regarding the regulation of loc285194. Moreover, the underlying mechanism by which loc285194 functions as a potential tumor suppressor is elusive. In this study, we show that loc285194 is a p53 transcription target; ectopic expression of loc285194 inhibits tumor cell growth both in vitro and in vivo. Through deletion analysis, we identify an active region responsible for tumor cell growth inhibition within exon 4, which harbors two miR-211 binding sites. Importantly, this loc285194-mediated growth inhibition is in part due to specific suppression of miR-211. We further demonstrate a reciprocal repression between loc285194 and miR-211; in contrast to loc285194, miR-211 promotes cell growth. Finally, we detect downregulation of loc285194 in colon cancer specimens by quantitative PCR arrays and in situ hybridization of tissue microarrays. Together, these results suggest that loc285194 is a p53-regulated tumor suppressor, which acts in part through repression of miR-211.
Liu, Qian; Huang, Jianguo; Zhou, Nanjiang; Zhang, Ziqiang; Zhang, Ali; Lu, Zhaohui; Wu, Fangting; Mo, Yin-Yuan
Exploring brain connectivity is fundamental to understanding the functional architecture of the cortex. In our study we employed tractography-based parcellation, combined with the principal component analysis statistical framework, to divide the occipital lobes into seven areas in a group of eighteen healthy participants. Tractography-based parcellation is a method based on diffusion imaging tractography, which segregates the living human brain into distinctive areas showing sharp differences in their anatomical connectivity. The results were compared to covarying functional networks involving distinct areas within the occipital lobes, that we obtained using resting state functional magnetic resonance imaging (fMRI), as well as to other existing subdivisions of the occipital lobes. Our results showed similarities with functional imaging data in healthy controls and cognitive profiles in brain-damaged patients, although several differences with cytoarchitectonic, myelogenetic, myeloarchitectonic and functional maps were reported. While the similarities are encouraging, the potential validity and limitations of the differences observed are discussed. Taken together these results suggest that tractography-based parcellation may provide a new promising anatomical subdivision of the living human brain based on its anatomical connectivity, which may benefit the understanding of clinical-neuroanatomical dissociations and functional neuroimaging results. PMID:23312799
Thiebaut de Schotten, Michel; Urbanski, Marika; Valabregue, Romain; Bayle, Dimitri J; Volle, Emmanuelle
Using simultaneous electroencephalography as a measure of ongoing activity and functional magnetic resonance imaging (fMRI) as a measure of the stimulus-driven neural response, we examined whether the amplitude and phase of occipital alpha oscillations at the onset of a brief visual stimulus affects the amplitude of the visually evoked fMRI response. When accounting for intrinsic coupling of alpha amplitude and occipital fMRI signal by modeling and subtracting pseudo-trials, no significant effect of prestimulus alpha amplitude on the evoked fMRI response could be demonstrated. Regarding the effect of alpha phase, we found that stimuli arriving at the peak of the alpha cycle yielded a lower blood oxygenation level-dependent (BOLD) fMRI response in early visual cortex (V1/V2) than stimuli presented at the trough of the cycle. Our results therefore show that phase of occipital alpha oscillations impacts the overall strength of a visually evoked response, as indexed by the BOLD signal. This observation complements existing evidence that alpha oscillations reflect periodic variations in cortical excitability and suggests that the phase of oscillations in postsynaptic potentials can serve as a mechanism of gain control for incoming neural activity. Finally, our findings provide a putative neural basis for observations of alpha phase dependence of visual perceptual performance. PMID:21389236
Scheeringa, René; Mazaheri, Ali; Bojak, Ingo; Norris, David G; Kleinschmidt, Andreas
Extensive research has demonstrated that several specialized cortical regions respond preferentially to faces. One such region, located in the inferior occipital gyrus, has been dubbed the occipital face area (OFA). The OFA is the first stage in two influential face-processing models, both of which suggest that it constructs an initial representation of a face, but how and when it does so remains unclear. The present study revealed that repetitive transcranial magnetic stimulation (rTMS) targeted at the right OFA (rOFA) disrupted accurate discrimination of face parts but had no effect on the discrimination of spacing between these parts. rTMS to left OFA had no effect. A matched part and spacing discrimination task that used house stimuli showed no impairment. In a second experiment, rTMS to rOFA replicated the face-part impairment but did not produce the same effect in an adjacent area, the lateral occipital cortex. A third experiment delivered double pulses of TMS separated by 40 ms at six periods after stimulus presentation during face-part discrimination. Accuracy dropped when pulses were delivered at 60 and 100 ms only. These findings indicate that the rOFA processes face-part information at an early stage in the face-processing stream. PMID:17764942
Pitcher, David; Walsh, Vincent; Yovel, Galit; Duchaine, Bradley
Occipital epilepsies often elude diagnosis as they frequently masquerade as other seizure syndromes. Visual hallucinations are the key clinical symptoms indicating an occipital focus, but may be difficult to elicit on history, especially from children, and are not always present. When visual symptoms are not prominent, the seizure semiology and scalp EEG may lead the clinician away from considering an occipital focus, as they often reflect seizure propagation rather than seizure origin. Clinical and neuroimaging advances have led to the recognition of many new occipital epilepsy syndromes, which generally present in childhood or adolescence. Major groups include malformations of cortical development [focal cortical dysplasia, periventricular heterotopia (PVH), subcortical band heterotopia (SBH), polymicrogyria], vascular (including epilepsy with bilateral occipital calcifications often associated with coeliac disease), metabolic and the emerging idiopathic occipital epilepsies. The idiopathic occipital epilepsies now comprise three identifiable electroclinical syndromes of childhood and adolescence, the biological inter-relationships and overlap with idiopathic generalized epilepsies of which are discussed here. We emphasize the clues to recognition of specific occipital epilepsies, some of which now have specific treatments. Where medical therapy is ineffective, occipital corticectomy should be considered. Emerging evidence suggests that some syndromes have a good surgical outcome, and the consequences to visual function may be less severe than anticipated. PMID:12615636
Taylor, Isabella; Scheffer, Ingrid E; Berkovic, Samuel F
Traditionally, it has been theorized that the human visual system identifies and classifies scenes in an object-centered approach, such that scene recognition can only occur once key objects within a scene are identified. Recent research points toward an alternative approach, suggesting that the global image features of a scene are sufficient for the recognition and categorization of a scene. We have previously shown that disrupting object processing with repetitive TMS to object-selective cortex enhances scene processing possibly through a release of inhibitory mechanisms between object and scene pathways [Mullin, C. R., & Steeves, J. K. E. TMS to the lateral occipital cortex disrupts object processing but facilitates scene processing. Journal of Cognitive Neuroscience, 23, 4174-4184, 2011]. Here we show the effects of TMS to the transverse occipital sulcus (TOS), an area implicated in scene perception, on scene and object processing. TMS was delivered to the TOS or the vertex (control site) while participants performed an object and scene natural/nonnatural categorization task. Transiently interrupting the TOS resulted in significantly lower accuracies for scene categorization compared with control conditions. This demonstrates a causal role of the TOS in scene processing and indicates its importance, in addition to the parahippocampal place area and retrosplenial cortex, in the scene processing network. Unlike TMS to object-selective cortex, which facilitates scene categorization, disrupting scene processing through stimulation of the TOS did not affect object categorization. Further analysis revealed a higher proportion of errors for nonnatural scenes that led us to speculate that the TOS may be involved in processing the higher spatial frequency content of a scene. This supports a nonhierarchical model of scene recognition. PMID:23410031
Ganaden, Rachel E; Mullin, Caitlin R; Steeves, Jennifer K E
The inferior fronto-occipital fasciculus (IFOF) is historically described as the longest associative bundle in the human brain and it connects various parts of the occipital cortex, temporo-basal area and the superior parietal lobule to the frontal lobe through the external/extreme capsule complex. The exact functional role and the detailed anatomical definition of the IFOF are still under debate within the scientific community. In this study we present a fiber tracking dissection of the right and left IFOF by using a q-ball residual-bootstrap reconstruction of High-Angular Resolution Diffusion Imaging (HARDI) data sets in 20 healthy subjects. By defining a single seed region of interest on the coronal fractional anisotropy (FA) color map of each subject, we investigated all the pathways connecting the parietal, occipital and posterior temporal cortices to the frontal lobe through the external/extreme capsule. In line with recent post-mortem dissection studies we found more extended anterior-posterior association connections than the “classical” fronto-occipital representation of the IFOF. In particular the pathways we evidenced showed: a) diffuse projections in the frontal lobe, b) fronto-parietal lobes connections trough the external capsule in almost all the subjects and c) widespread connections in the posterior regions. Our study represents the first consistent in vivo demonstration across a large group of individuals of these novel anterior and posterior terminations of the IFOF detailed described only by post-mortem anatomical dissection. Furthermore our work establishes the feasibility of consistent in vivo mapping of this architecture with independent in vivo methodologies. In conclusion q-ball tractography dissection supports a more complex definition of IFOF, which includes several subcomponents likely underlying specific function.
Amirbekian, Bagrat; Berger, Mitchel S.; Henry, Roland G.
The visual P300 brain-computer interface (BCI), a popular system for electroencephalography (EEG)-based BCI, uses the P300 event-related potential to select an icon arranged in a flicker matrix. In earlier studies, we used green/blue (GB) luminance and chromatic changes in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray (WG) luminance flicker matrix. To highlight areas involved in improved P300-BCI performance, we used simultaneous EEG-fMRI recordings and showed enhanced activities in bilateral and right lateralized parieto-occipital areas. Here, to capture coherent activities of the areas during P300-BCI, we collected whole-head 306-channel magnetoencephalography data. When comparing functional connectivity between the right and left parieto-occipital channels, significantly greater functional connectivity in the alpha band was observed under the GB flicker matrix condition than under the WG flicker matrix condition. Current sources were estimated with a narrow-band adaptive spatial filter, and mean imaginary coherence was computed in the alpha band. Significantly greater coherence was observed in the right posterior parietal cortex under the GB than under the WG condition. Re-analysis of previous EEG-based P300-BCI data showed significant correlations between the power of the coherence of the bilateral parieto-occipital cortices and their performance accuracy. These results suggest that coherent activity in the bilateral parieto-occipital cortices plays a significant role in effectively driving the P300-BCI. PMID:24860546
Takano, Kouji; Ora, Hiroki; Sekihara, Kensuke; Iwaki, Sunao; Kansaku, Kenji
The visual P300 brain–computer interface (BCI), a popular system for electroencephalography (EEG)-based BCI, uses the P300 event-related potential to select an icon arranged in a flicker matrix. In earlier studies, we used green/blue (GB) luminance and chromatic changes in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray (WG) luminance flicker matrix. To highlight areas involved in improved P300-BCI performance, we used simultaneous EEG–fMRI recordings and showed enhanced activities in bilateral and right lateralized parieto-occipital areas. Here, to capture coherent activities of the areas during P300-BCI, we collected whole-head 306-channel magnetoencephalography data. When comparing functional connectivity between the right and left parieto-occipital channels, significantly greater functional connectivity in the alpha band was observed under the GB flicker matrix condition than under the WG flicker matrix condition. Current sources were estimated with a narrow-band adaptive spatial filter, and mean imaginary coherence was computed in the alpha band. Significantly greater coherence was observed in the right posterior parietal cortex under the GB than under the WG condition. Re-analysis of previous EEG-based P300-BCI data showed significant correlations between the power of the coherence of the bilateral parieto-occipital cortices and their performance accuracy. These results suggest that coherent activity in the bilateral parieto-occipital cortices plays a significant role in effectively driving the P300-BCI.
Takano, Kouji; Ora, Hiroki; Sekihara, Kensuke; Iwaki, Sunao; Kansaku, Kenji
The human cortical system for face perception is comprised of a network of connected regions including the middle fusiform gyrus ("fusiform face area" or FFA), the inferior occipital cortex ("occipital face area" or OFA), and the superior temporal sulcus. The traditional hierarchical feedforward model of visual processing suggests information flows from early visual cortex to the OFA for initial face feature analysis to higher order regions including the FFA for identity recognition. However, patient data suggest an alternative model. Patients with acquired prosopagnosia, an inability to visually recognize faces, have been documented with lesions to the OFA but who nevertheless show face-selective activation in the FFA. Moreover, their ability to categorize faces remains intact. This suggests that the FFA is not solely responsible for face recognition and the network is not strictly hierarchical, but may be organized in a reverse hierarchical fashion. We used transcranial magnetic stimulation (TMS) to temporarily disrupt processing in the OFA in neurologically-intact individuals and found participants' ability to categorize intact versus scrambled faces was unaffected, however face identity discrimination was significantly impaired. This suggests that face categorization but not recognition can occur without the "earlier" OFA being online and indicates that "lower level" face category processing may be assumed by other intact face network regions such as the FFA. These results are consistent with the patient data and support a non-hierarchical, global-to-local model with re-entrant connections between the OFA and other face processing areas. PMID:24077427
Solomon-Harris, Lily M; Mullin, Caitlin R; Steeves, Jennifer K E
Data derived from massive cloning and traditional sequencing methods have revealed that long non-coding RNAs (lncRNA) play important roles in the development and progression of cancer. Although many studies suggest that the lncRNAs have different cellular functions, many of them are not yet to be identified and characterized for the mechanism of their functions. To address this question, we assay the expression level of lncRNAs-Loc554202 in breast cancer tissues and find that Loc554202 is significantly increased compared with normal control, and associated with advanced pathologic stage and tumor size. Moreover, knockdown of Loc554202 decreased breast cancer cell proliferation, induced apoptosis and inhibits migration/invasion in vitro and impeded tumorigenesis in vivo. These data suggest an important role of Loc554202 in breast tumorigenesis. PMID:24631686
Shi, Yongguo; Lu, Jianwei; Zhou, Jing; Tan, Xueming; He, Ye; Ding, Jie; Tian, Yun; Wang, Li; Wang, Keming
Diffusion tensor imaging (DTI) and fiber tracking (FT) were used to measure the occipital lobe fiber tracts connecting the two hemispheres in individual human subjects. These tracts are important for normal vision. Also, damage to portions of these tracts is associated with alexia. To assess the reliability of the DTI-FT measurements, occipital-callosal projections were estimated from each subject's left and
Michal Ben-Shachar; Roland Bammer; Alyssa A. Brewer; Brian A. Wandell
The association of epilepsy, occipital calcifications, and celiac disease has been recognized as a distinct syndrome. The objective of this study was to present the clinical, electrophysiologic, and neuroradiologic features in a series of patients with this syndrome. Thirty-two patients with the constellation of epilepsy, occipital calcifications, and celiac disease were identified in our epilepsy clinic. The mean age was
Hugo A. Arroyo; Susana De Rosa; Victor Ruggieri; María T. G. de Dávila; Natalio Fejerman
This paper reports the investigation into Lead-On-Chip (LOG) package cracking resistance, the effects of mold compound properties, and the package cracking predication. The vehicle for such investigation was a DRAM LOC package and four mold compounds under two IR reflow processes (220°C and 260°C). As the reliability of the LOC package is strongly dependent on the mechanical properties of the
YANG Ji-Cheng; Leong Chew Weng; Goh Jing Sua; Yew Chee Kiang
Summary The feasibility of producing a visual prosthesis for the blind using intracorticai microstimulation (ICMS) of the visual cortex was studied in a 42-year-old woman who had been totally blind for 22 years secondary to glaucoma. Thirty- eight microelectrodes were implanted in the right visual cortex, near the occipital pole, for a period of 4 months. Percepts reported as small
E. M. Schmidt; M. J. Bak; F. T. Hambrecht; C. V. Kufta; D. K. O'Rourke; P. Vallabhanath
Chronic daily headache is a major worldwide health problem that affects 3–5% of the population and results in substantial disability. Advances in the management of headache disorders have meant that a substantial proportion of patients can be effectively treated with medical treatments. However, a significant minority of these patients are intractable to conventional medical treatments. Occipital nerve stimulation (ONS) is emerging as a promising treatment for patients with medically intractable, highly disabling chronic headache disorders, including migraine, cluster headache and other less common headache syndromes. Open-label studies have suggested that this treatment modality is effective and recent controlled trial data are also encouraging. The procedure is performed using several technical variations that have been reviewed along with the complications, which are usually minor and tolerable. The mechanism of action is poorly understood, though recent data suggest that ONS could restore the balance within the impaired central pain system through slow neuromodulatory processes in the pain neuromatrix. While the available data are very encouraging, the ultimate confirmation of the utility of a new therapeutic modality should come from controlled trials before widespread use can be advocated; more controlled data are still needed to properly assess the role of ONS in the management of medically intractable headache disorders. Future studies also need to address the variables that are predictors of response, including clinical phenotypes, surgical techniques and stimulation parameters.
Compared to objects, pictures of faces elicit a larger early electromagnetic response at occipito-temporal sites on the human scalp, with an onset of 130?ms and a peak at about 170?ms. This N170 face effect is larger in the right than the left hemisphere and has been associated with the early categorization of the stimulus as a face. Here we tested whether this effect can be observed in the absence of some of the visual areas showing a preferential response to faces as typically identified in neuroimaging. Event-related potentials were recorded in response to faces, cars, and their phase-scrambled versions in a well-known brain-damaged case of prosopagnosia (PS). Despite the patient’s right inferior occipital gyrus lesion encompassing the most posterior cortical area showing preferential response to faces (“occipital face area”), we identified an early face-sensitive component over the right occipito-temporal hemisphere of the patient that was identified as the N170. A second experiment supported this conclusion, showing the typical N170 increase of latency and amplitude in response to inverted faces. In contrast, there was no N170 in the left hemisphere, where PS has a lesion to the middle fusiform gyrus and shows no evidence of face-preferential response in neuroimaging (no left “fusiform face area”). These results were replicated by a magnetoencephalographic investigation of the patient, disclosing a M170 component only in the right hemisphere. These observations indicate that face-preferential activation in the inferior occipital cortex is not necessary to elicit early visual responses associated with face perception (N170/M170) on the human scalp. These results further suggest that when the right inferior occipital cortex is damaged, the integrity of the middle fusiform gyrus and/or the superior temporal sulcus – two areas showing face-preferential responses in the patient’s right hemisphere – might be necessary to generate the N170 effect.
Prieto, Esther Alonso; Caharel, Stephanie; Henson, Richard; Rossion, Bruno
Peripheral nerve stimulation of the occipital nerve has a favourable efficacy to safety profile for chronic migraine, which is notoriously difficult to treat. This article covers the rationale, surgical procedure and clinical data for this treatment option. PMID:23411977
Ashkan, Keyoumars; Dowson, Andrew
Vertigo, dizziness and visual blurring have been reported in painful conditions in trigeminal innervation zones such as in idiopathic stabbing headache, supraorbital neuralgia or trigeminal nerve ophthalmic branch neuralgia. Although not common, pain in occipital neuralgia can spread through the anterior parts of the head. In this article, we present a case whose occipital neuralgiform paroxysms spread to the ipsilateral eye with simultaneous visual obscuration; the mechanisms of propagation and visual obscuration are discussed. PMID:20865585
Selekler, Hamit Macit; Dündar, Gülmine; Kutlu, Ay?e
The authors report their experience on one patient with hypersexuality from resection of left occipital arteriovenous malformation.\\u000a To the best of our knowledge, this is the first case reported in the literature. A 35-year-old right-handed female farmer\\u000a suffered a sudden left occipital hemorrhage with subarachnoid and subdural hemorrhages of the left hemisphere. Transient left\\u000a uncal herniation occurred at the onset
Yong Cao; Zhaohui Zhu; Rong Wang; Shuo Wang; Jizong Zhao
We present 2 term newborn infants with apneic seizure originating in the occipital lobe that was diagnosed by video-EEG. One infant had ischemic infarction in the distribution of the posterior cerebral artery, extending to the cingulate gyrus. In the other infant, only transient occipital hyperechogenicity was observed by using neurosonography. In both cases, although the critical EEG discharge was observed at the occipital level, the infants presented no clinical manifestations. In patient 1, the discharge extended to the temporal lobe first, with subtle motor manifestations and tachycardia, then synchronously to both hemispheres (with bradypnea/hypopnea), and the background EEG activity became suppressed, at which point the infant experienced apnea. In patient 2, background EEG activity became suppressed right at the end of the focal discharge, coinciding with the appearance of apnea. In neither case did the clinical description by observers coincide with video-EEG findings. The existence of connections between the posterior limbic cortex and the temporal lobe and midbrain respiratory centers may explain the clinical symptoms recorded in these 2 cases. The novel features reported here include video-EEG capture of apneic seizure, ischemic lesion in the territory of the posterior cerebral artery as the cause of apneic seizure, and the appearance of apnea when the epileptiform ictal discharge extended to other cerebral areas or when EEG activity became suppressed. To date, none of these clinical findings have been previously reported. We believe this pathology may in fact be fairly common, but that video-EEG monitoring is essential for diagnosis. PMID:22641764
Castro Conde, José Ramón; González-Hernández, Tomás; González Barrios, Desiré; González Campo, Candelaria
Neurologic dysfunction accompanied by malformation of both the skull and the cervical vertebrae has been previously described in lions kept in captivity worldwide, and this dysfunction and malformation were most often related to vitamin A deficiency. Diagnosis of the bone malformation and its effects on the neural tissue was until recently limited to postmortem examination, with characteristic thickening of the bones of the cranial vault, cerebellar herniation, compression of the foramen magnum, and enlargement of the lateral ventricles. For some mildly affected lion cubs with neurologic signs, improvement was reported with excessive vitamin A supplementation. However, definitive diagnosis was only available for those that eventually died or were euthanized. This case documents the antemortem diagnosis of the disease using computed tomographic imaging and liver biopsy. While conservative treatment failed, suboccipital craniectomy removed the thickened occipital bone and was demonstrated to be a successful surgical intervention that can be used to treat more severely affected lions. PMID:18817011
Shamir, Merav H; Shilo, Yael; Fridman, Alon; Chai, Orit; Reifen, Ram; Miara, Limor
In a model with weak bosons based on the SU(2)/sub L//sup loc/ x U(1)/sub Y//sup loc/ symmetry, excited weak gauge bosons, W* and Z*, are introduced as composites generated by four Fermi interactions. From the complementarity viewpoint that requires a new...
Benign occipital seizure syndromes are benign childhood epilepsy syndromes and are mainly of two types, Panayiotopoulos syndrome, an autonomic epilepsy and idiopathic childhood occipital epilepsy of Gastaut (ICOE-G) including the idiopathic photosensitive occipital lobe epilepsy. Although both these types are categorized as occipital seizures, they are distinct in presentation and management. They can also be tricky to diagnose as visual symptoms may not always be the presenting feature and it is also not very easy to elicit visual hallucinations during history taking. These seizures have a good response to treatment; however, there could be atypical evolution and refractoriness to treatment especially with ICOE-G. We describe three children who presented with visual and non-visual symptoms and the electroencephalography (EEG) in all the three cases showed occipital paroxysms. We have emphasized the clues in the clinical history and EEG leading to the diagnosis of these distinct epilepsy syndromes. We have also discussed the natural course of these epilepsy syndromes with some atypical evolution, which clinicians need to be aware of during treatment of these children.
Chary, Prithika; Rajendran, Bhuvaneshwari
Studies the performance of freshmen biology and physics-mathematics majors and chemistry majors as well as pre- and in-service chemistry teachers at two Israeli universities on algorithmic (ALG), lower-order cognitive skills (LOCS), and higher-order cognitive skills (HOCS) chemistry exam questions. Finds that students in both universities…
LOC3D (http://cubic.bioc.columbia.edu/db/LOC3d/) is both a weekly-updated database and a web server for predictions of sub-cellular localization for eukaryotic proteins of known three-dimensional (3D) structure. Localization is predicted using four different methods: (i) PredictNLS, prediction of nuclear proteins through nuclear localization signals; (ii) LOChom, inferring localization through sequence homology; (iii) LOCkey, inferring localization through automatic text analysis of SWISS-PROT keywords; and (iv) LOC3Dini, ab initio prediction through a system of neural networks and vector support machines. The final prediction is based on the method that predicts localization with the highest confidence. The LOC3D database currently contains predictions for >8700 eukaryotic protein chains taken from the Protein Data Bank (PDB). The web server can be used to predict sub-cellular localization for proteins for which only a predicted structure is available from threading servers. This makes the resource of particular interest to structural genomics initiatives.
Nair, Rajesh; Rost, Burkhard
The experiment operating procedure for Test LOC-5 is described. The test will be performed using four, separately shrouded fuel rods of PWR 15 x 15 design. Two rods have been previously irradiated and two rods will be unirradiated. One unirradiated and one irradiated rod will be backfilled with helium to a pressure typical of beginning-of-life PWR fuel rods, and the
BACKGROUND: Knowledge of subcellular localization of proteins is crucial to proteomics, drug target discovery and systems biology since localization and biological function are highly correlated. In recent years, numerous computational prediction methods have been developed. Nevertheless, there is still a need for prediction methods that show more robustness and higher accuracy. RESULTS: We extended our previous MultiLoc predictor by incorporating
Torsten Blum; Sebastian Briesemeister; Oliver Kohlbacher
Bear attacks are reported from nearly every part of the world. The chance of a human encountering a bear increases as the remote bear territory diminishes. The sloth bear is one of the three species of bears found in India, which inhabits the forests of India and its neighboring countries. Here we describe a teenager who came to us with a critical injury involving the face, temporal and occipital bones inflicted by a sloth bear attack. He underwent a temporal exploration, facial nerve decompression, pinna reconstruction, and occipital bone repair to save him from fatality. PMID:24396623
Prasad, Sampath Chandra; Thada, Nikhil Dinaker; Rao, Pallavi; Thada, Smitha Rani; Prasad, Kishore Chandra
Bilateral cortical blindness and Anton syndrome, are most commonly caused by ischaemic stroke. In this condition, patients have loss of vision but deny their blindness despite objective evidence of visual loss. We report a case of a patient with multiple cardiovascular risk factors who developed recurrent bilateral occipital lobe infarct with Anton syndrome. A suspicion of this condition should be raised when the patient has denial of blindness in the presence of clinical and radiological evidence of occipital lobe injury. Management of this condition should focus on the underlying cause, in which our patient requires secondary stroke prevention and rehabilitation.
Kwong Yew, Kiu; Abdul halim, Sanihah; Tharakan, John
Subcutaneous stimulation of the occipital nerve has been reported using percutaneously placed spinal cord stimulator electrodes. Occasionally, gradual loss of effectiveness has been noted possibly due to scar formation around the contacts. We report on the use of the Medtronic Resume II(R), peripheral nerve / spinal cord stimulator electrode for causing peripheral stimulation of the occipital nerve in the suboccipital region. Initial results suggest improved stimulation with lower power requirements using this larger electrode. The larger contact size might lessen the effect of scar formation and offer improved stimulation over a longer period. PMID:16871305
Jones, Rodney L
Background The greater occipital nerve (GON) block has been frequently used for different types of headache, but performed with rough estimates of anatomic landmarks. Our study presents the values of the anatomic parameters and estimates the effectiveness of the ultrasound-guided GON blockade. Methods The GON was detected using ultrasound technique and distance from external occipital protuberance (EOP) to GON, from GON to occipital artery and depth from skin to GON was measured in volunteers. Patients with occipital headache were divided into two groups (ultrasound-guided block: group S, conventional blind block: group B) and GON block was performed. The same parameters were measured on group S and VAS scores were assessed at pretreatment, 1 week and 4 weeks after treatment on both groups. Results The GON had distance of 23.1 ± 3.4 mm (right) and 20.5 ± 2.8 mm (left) from EOP to GON. Its depth below the skin was 6.8 ± 1.5 mm (right) and 7.0 ± 1.3 mm (left). The distance from GON to occipital artery was 1.5 ± 0.6 mm (right) and 1.2 ± 0.6 mm (left) in volunteers. Initial VAS score of group S and group B patients were 6.4 ± 0.2 and 6.5 ± 0.2. VAS score of 4 weeks after injection were 2.3 ± 0.2 on group S and 3.8 ± 0.3 on group B (P = 0.0003). Conclusions The parameters measured in this study should be useful for GON block and ultrasound-guided blockade is likely to be a more effective technique than blind blockade in occipital headache treatment.
Shim, Jae Hang; Ko, So Young; Bang, Mi Rang; Jeon, Woo Jae; Cho, Sang Yun; Yeom, Jong Hoon; Shin, Woo Jong; Kim, Kyoung Hun
Background The loss of vision has been associated with enhanced performance in non-visual tasks such as tactile discrimination and sound localization. Current evidence suggests that these functional gains are linked to the recruitment of the occipital visual cortex for non-visual processing, but the neurophysiological mechanisms underlying these crossmodal changes remain uncertain. One possible explanation is that visual deprivation is associated with an unmasking of non-visual input into visual cortex. Methodology/Principal Findings We investigated the effect of sudden, complete and prolonged visual deprivation (five days) in normally sighted adult individuals while they were immersed in an intensive tactile training program. Following the five-day period, blindfolded subjects performed better on a Braille character discrimination task. In the blindfold group, serial fMRI scans revealed an increase in BOLD signal within the occipital cortex in response to tactile stimulation after five days of complete visual deprivation. This increase in signal was no longer present 24 hours after blindfold removal. Finally, reversible disruption of occipital cortex function on the fifth day (by repetitive transcranial magnetic stimulation; rTMS) impaired Braille character recognition ability in the blindfold group but not in non-blindfolded controls. This disruptive effect was no longer evident once the blindfold had been removed for 24 hours. Conclusions/Significance Overall, our findings suggest that sudden and complete visual deprivation in normally sighted individuals can lead to profound, but rapidly reversible, neuroplastic changes by which the occipital cortex becomes engaged in processing of non-visual information. The speed and dynamic nature of the observed changes suggests that normally inhibited or masked functions in the sighted are revealed by visual loss. The unmasking of pre-existing connections and shifts in connectivity represent rapid, early plastic changes, which presumably can lead, if sustained and reinforced, to slower developing, but more permanent structural changes, such as the establishment of new neural connections in the blind.
Merabet, Lotfi B.; Hamilton, Roy; Schlaug, Gottfried; Swisher, Jascha D.; Kiriakopoulos, Elaine T.; Pitskel, Naomi B.; Kauffman, Thomas; Pascual-Leone, Alvaro
A dermal sinus is a congenital defect arising from a closure failure of the neural tube that results in different degrees of communication between the skin and the central nervous system. A dermal sinus can occur anywhere from the root of the nose to the conus medullaris, and the occipital location is the second most common. Dermal sinuses are often
A. García Galera; M. I. Martínez León; S. Pérez da Rosa; B. Ros López
The early and late benign occipital epilepsies of childhood (BOEC) are described as two discrete electro-clinical syndromes, eponymously known as Panayiotopoulos and Gastaut syndromes. Our aim was to explore the clinical features, classification and clinical genetics of these syndromes using twin and multiplex family studies to determine whether…
Taylor, Isabella; Berkovic, Samuel F.; Kivity, Sara; Scheffer, Ingrid E.
Objectives To describe use of bilateral temporal and occipital stimulator leads for a refractory headache disorder. Materials and methods A 31-year-old female had a 10-year history of chronic, severe occipital and temporal region headaches. The patient underwent permanent implant of an occipital stimulator system that resulted in sustained, compete resolution of her occipital pain. However, she continued to suffer disabling (10/10) temporal region headaches and was bedbound most days of the week. Therefore, bilateral temporal stimulator leads were implanted and tunneled to her internal pulse generator. Results At 12-month follow-up, the patient enjoyed sustained improvement in her pain scores (8/10) and marked increase in her level of functioning. Taking into account increased activity level, she rated her overall improvement at 50%. Unfortunately, infection and erosion of her right temporal lead necessitated temporal stimulator removal. Conclusion Headache disorders may require stimulation of all painful cephalic regions. However, our success in this case must be considered in light of the technical challenges and expense of placing stimulator leads subcutaneously around the head and neck, including the risk of infection, lead breakage, erosion, and migration.
Zach, Kelly J; Trentman, Terrence L; Zimmerman, Richard S; Dodick, David W
The purpose of this document is to specify the experiment operating procedure for Test LOC-3. The test will be performed using four, separately shrouded fuel rods of PWR 15x15 design. Two rods have been previously irradiated and two rods will be unirradiated. One unirradiated and one irradiated rod will be backfilled with helium to a pressure typical of beginning-of-life PWR
This paper presents a simple and reliable multi-immunosensing lab-on-a-chip detecting antibodies as multi-disease markers using electrochemical method suitable for a portable point-of-care system. Since multi-immunosensing LOCs are to be disposable and cheap, the complications associated with the liquid control need to be removed. The main complication arises from the active microfluidic part driven by the external electric power. In this paper, a multi-stacked PDMS LOC including PDMS passive valves is proposed. The sequential liquid driving by capillary attraction and the action of check valve provide a reliable immunosensing tool simply triggered by an air bladder push without an electrical power. The immunosensing-LOC with the size of "25mm × 20mm × 6 mm" is fabricated with PDMS using the replica molding and oxygen plasma bonding. The LOC consists of a PDMS valve, channel, and a glass substrate. The fluidic tests were performed using DI water. The liquids are controlled by two kinds of passive valve, one is capillary stop valve and the other is membrane type check valve. The capillary stop valve stops liquids using pressure barrier of expanded channel. The check valve stops the liquid triggered by an air bladder from flowing backward. The assembly of these two valves assures the well controlled liquid driving for the immunosensing. The model experiments were performed with anti-DNP antibody and anti-biotin antibody as target analytes. The antibodies conjugated with GOX are used as a signaling molecule for cyclic voltammetry. The different amplified signals show different target analyte affinities and make sure the multi-immunosensing.
Kang, Tae Ho; Park, Sin Wook; Lee, Jun Hwang; Yoon, Hyun C.; Yang, Sang Sik
Twenty-six patients were studied who had the clinical and electroencephalographic features of benign childhood epilepsy with occipital paroxysms (BCEOP) as defined by the Commission of the International League Against Epilepsy (ILAE). Twelve patients were characterized as having early-onset benign childhood occipital seizures (EBOS) susceptible syndrome, as described by Panayiotopoulos, and 14 patients had late onset childhood idiopathic occipital seizures (LOS).
Min-Lan Tsai; Hsin-Yu Lo; Wun-Tsong Chaou
We present a method called ngLOC, an n-gram-based Bayesian classifier that predicts the localization of a protein sequence over ten distinct subcellular organelles. A tenfold cross-validation result shows an accuracy of 89% for sequences localized to a single organelle, and 82% for those localized to multiple organelles. An enhanced version of ngLOC was developed to estimate the subcellular proteomes of eight eukaryotic organisms: yeast, nematode, fruitfly, mosquito, zebrafish, chicken, mouse, and human.
King, Brian R; Guda, Chittibabu
BackgroundThe loss of vision has been associated with enhanced performance in non-visual tasks such as tactile discrimination and sound localization. Current evidence suggests that these functional gains are linked to the recruitment of the occipital visual cortex for non-visual processing, but the neurophysiological mechanisms underlying these crossmodal changes remain uncertain. One possible explanation is that visual deprivation is associated with
Lotfi B. Merabet; Roy Hamilton; Gottfried Schlaug; Jascha D. Swisher; Elaine T. Kiriakopoulos; Naomi B. Pitskel; Thomas Kauffman; Alvaro Pascual-Leone; David C. Burr
The occipital interhemispheric transtentorial approach is commonly used for pineal region tumors. However, there are few reports of this approach for lesions in the superior cerebellum. We present a 47-year-old male patient with an incidental cystic lesion in the superior cerebellum, detected on MRI consistent with cerebellar hemangioblastoma. The patient initially underwent stereotactic radiosurgery. After 5 months he presented with dizziness. A repeat MRI scan revealed an interval increase in lesion size. We performed surgery using the occipital interhemispheric transtentorial approach to remove the lesion. There were no intraoperative complications and the patient tolerated the procedure well. We describe our approach, supplemented by a short video, and review operative approaches to the superior cerebellum. PMID:20947356
Cardenas, Raul J; Javalkar, Vijayakumar; Ezer, Haim; Burnham, Jeremy; Nanda, Anil
A dermal sinus is a congenital defect arising from a closure failure of the neural tube that results in different degrees of communication between the skin and the central nervous system. A dermal sinus can occur anywhere from the root of the nose to the conus medullaris, and the occipital location is the second most common. Dermal sinuses are often found in association with dermoid or epidermoid cysts and less frequently with teratomas. Patients with an occipital dermoid cyst associated with a dermal sinus can develop meningitis and/or abscesses as the first clinical manifestation of the disease due to the dermoid cyst itself becoming abscessed or to the formation of secondary abscesses; few cases of the formation of secondary abscesses have been reported. We present a case of a dermoid cyst associated with an infected dermal sinus and posterior development of cerebellar abscesses and hydrocephalus. PMID:22130510
García Galera, A; Martínez León, M I; Pérez da Rosa, S; Ros López, B
A rare case of a giant, temporo-occipital sinus pericranii is presented. A 38-year-old male presented with minor symptoms of headache and heaviness over an enlarging temporo-occipital bone defect. Within the defect a soft, compressible, mass lesion was observed, which varied in size with changes in intracranial pressure. Radiological imaging demonstrated bone erosion around a fluid filled mass, which on angiography communicated via a series of channels with the transverse sinus. A diagnosis of sinus pericranii was made. Due to the risk of future complication the patient elected to undergo surgery, which successfully resected the mass and obliterated the venous communications with the diploic veins and transverse sinus. The classification, aetiology, differential diagnosis, radiological characteristics and management options relating to sinus pericranii are discussed. PMID:11533535
Marras, C; McEvoy, A W; Grieve, J P; Jäger, H R; Kitchen, N D; Villani, R M
Occipital condylar fractures (OCFs) are rare and difficult to diagnose. The routine use of computed tomography (CT) scan in traumatology has however now made their diagnosis easier, with an estimated frequency of 4 to 19% of craniospinal traumatized patients and 0.4 to 0.7% of all severe traumatized patients in emergencies. This paper describes a patient who was not diagnosed with OCF during his first hospitalization after a road accident. However, 15 days later a left sided hypoglossal nerve palsy occurred. In this case report, we underline that an examination of the cranial nerve is a quick and easy procedure to screen each head trauma patient for occipital foramen fractures. Also, careful attention must be paid to X-Rays, CT scans and magnetic resonance imaging of the craniocervical junction. PMID:24475495
Rué, M; Jecko, V; Dautheribes, M; Vignes, J-R
Rapid-rate transcranial magnetic stimulation (rTMS) was administered to 10 healthy volunteers on different days over the right or left prefrontal cortex, midfrontal cortex, occipital cortex, or cerebellum. Mood (self-rated), reaction time, and hormone levels were serially measured. Consistent with a previous study, comparison of hemispheres revealed significant associations with decreased happiness after left prefrontal rTMS and decreased sadness after right prefrontal rTMS. Stimulation of all three prefrontal regions, but not the occipital or cerebellar regions, was associated with increases in serum thyroid-stimulating hormone. There was no effect on serum prolactin. rTMS applied to prefrontal cortex is safe and well tolerated and produces regionally and laterally specific changes in mood and neuroendocrine measures in healthy adults. rTMS is a promising tool for investigating prefrontal cortex functions. PMID:9081553
George, M S; Wassermann, E M; Williams, W A; Steppel, J; Pascual-Leone, A; Basser, P; Hallett, M; Post, R M
BACKGROUNDHydrocephalus and cerebellar abscesses as the principal manifestations of posterior fossa dermoid cyst are rare. In addition, extradural dermoid cyst of the posterior fossa has been described in only 9 cases in the literature. We present an unusual case of obstructive hydrocephalus due to cerebellar abscesses induced by an adjacent extradural dermoid cyst with complete occipital dermal sinus.CASE DESCRIPTIONA 14-month-old
Ali Akhaddar; Mohamed Jiddane; Noureddine Chakir; Rachid El Hassani; Brahim Moustarchid; Fouad Bellakhdar
We studied six children with ages ranging from 4 to 10 years who were affected by childhood epilepsy with occipital paroxysms\\u000a and presented after a stormy onset with prolonged loss of consciousness for 6–14 h. In all these patients, seizures were preceded\\u000a by visual symptoms in the form of colored circular disks. A CT scan was performed immediately after the
A. Verrotti; S. Domizio; D. Melchionda; M. Guerra; T. Mucedola; M. Onofrj; F. Chiarelli; G. Sabatino
To explore the neural substrates of visual–tactile crossmodal integration during motion direction discrimination, we conducted functional magnetic resonance imaging with 15 subjects. We initially performed independent unimodal visual and tactile experiments involving motion direction matching tasks. Visual motion discrimination activated the occipital cortex bilaterally, extending to the posterior portion of the superior parietal lobule, and the dorsal and ventral premotor
Satoru Nakashita; Daisuke N. Saito; Takanori Kochiyama; Manabu Honda; Hiroki C. Tanabe; Norihiro Sadato
Imaging studies in blind subjects have consistently shown that sensory and cognitive tasks evoke activity in the occipital cortex, which is normally visual. The precise areas involved and degree of activation are dependent upon the cause and age of onset of blindness. Here, we investigated the cortical language network at rest and during an…
Watkins, Kate E.; Cowey, Alan; Alexander, Iona; Filippini, Nicola; Kennedy, James M.; Smith, Stephen M.; Ragge, Nicola; Bridge, Holly
Directional transport of mRNA is a universal feature in eukaryotes, requiring the assembly of motor-dependent RNA-transport particles. The cytoplasmic transport of mRNAs is preceded by the nuclear assembly of pre-messenger ribonucleoprotein particles (mRNPs). In budding yeast, the asymmetric synthesis of HO 1 (ASH1) pre-mRNP originates already cotranscriptionally and passes through the nucleolus before its nuclear export. The nucleolar localization of ASH1 mRNA protein 1 (Loc1p) is required for efficient ASH1 mRNA localization. Immunoprecipitation experiments have revealed that Loc1p forms cocomplexes with other components of the ASH1 transport complex. However, it remains unclear how Loc1p is recruited into this mRNP and why Loc1p is important for ASH1 mRNA localization. Here we demonstrate that Loc1p undergoes a direct and specific interaction with the ASH1 mRNA-binding Swi5p-dependent HO expression protein 2 (She2p). This cocomplex shows higher affinity and specificity for RNA bearing localization elements than the individual proteins. It also stabilizes the otherwise transient binding of She2p to ASH1 mRNA, suggesting that cooperative mRNA binding of Loc1p with She2p is the required nuclear function of Loc1p for ASH1 mRNA localization. After nuclear export, myosin-bound She3p joins the ASH1 mRNP to form a highly specific cocomplex with She2p and ASH1 mRNA. Because Loc1p is found only in the nucleus, it must be removed from the complex directly before or after export. In vitro and in vivo experiments indicate that the synergistic interaction of She2p and She3p displaces Loc1p from the ASH1 complex, allowing free Loc1p to rapidly reenter the nucle(ol)us. Together these findings suggest an ordered process of nuclear assembly and reorganization for the maturation of localizing ASH1 mRNPs.
Niedner, Annika; Muller, Marisa; Moorthy, Balaji T.; Jansen, Ralf-Peter; Niessing, Dierk
Occipital neuralgia is a form of headache that involves the posterior occiput in the greater or lesser occipital nerve distribution. Pain can be severe and persistent with conservative treatment. We present a case of intractable occipital neuralgia that conventional therapeutic modalities failed to ameliorate. We speculate that, in this case, the cause of headache could be the greater occipital nerve entrapment by the obliquus capitis inferior muscle. After steroid and local anesthetic injection into obliquus capitis inferior muscles under fluoroscopic and sonographic guidance, the visual analogue scale was decreased from 9-10/10 to 1-2/10 for 2-3 weeks. The patient eventually got both greater occipital neurectomy and partial resection of obliquus capitis inferior muscles due to the short term effect of the injection. The successful steroid and local anesthetic injection for this occipital neuralgia shows that the refractory headache was caused by entrapment of greater occipital nerves by obliquus capitis inferior muscles.
Kim, Ok Sun; Jeong, Seung Min; Ro, Ji Young; Kim, Duck Kyoung; Koh, Young Cho; Ko, Young Sin; Lim, So Dug; Kim, Hae Kyoung
Cognitive control is required for correct performance on antisaccade tasks, including the ability to inhibit an externally driven ocular motor repsonse (a saccade to a peripheral stimulus) in favor of an internally driven ocular motor goal (a saccade directed away from a peripheral stimulus). Healthy humans occasionally produce errors during antisaccade tasks, but the mechanisms associated with such failures of cognitive control are uncertain. Most research on cognitive control failures focuses on post-stimulus processing, although a growing body of literature highlights a role of intrinsic brain activity in perceptual and cognitive performance. The current investigation used dense array electroencephalography and distributed source analyses to examine brain oscillations across a wide frequency bandwidth in the period prior to antisaccade cue onset. Results highlight four important aspects of ongoing and preparatory brain activations that differentiate error from correct antisaccade trials: (i) ongoing oscillatory beta (20–30Hz) power in anterior cingulate prior to trial initiation (lower for error trials), (ii) instantaneous phase of ongoing alpha-theta (7Hz) in frontal and occipital cortices immediately before trial initiation (opposite between trial types), (iii) gamma power (35–60Hz) in posterior parietal cortex 100 ms prior to cue onset (greater for error trials), and (iv) phase locking of alpha (5–12Hz) in parietal and occipital cortices immediately prior to cue onset (lower for error trials). These findings extend recently reported effects of pre-trial alpha phase on perception to cognitive control processes, and help identify the cortical generators of such phase effects.
Hamm, Jordan P.; Dyckman, Kara A.; McDowell, Jennifer E.; Clementz, Brett A.
Humans typically read at incredibly fast rates, because they predict likely occurring words from a given context. Here, we used functional near-infrared spectroscopy (fNIRS) to track the ultra-rapid hemodynamic responses of words presented every 280ms in a naturally paced sentence context. We found a lower occipital deoxygenation to unpredictable than to predictable words. The greater hemodynamic responses to unexpected words suggest that the visual features of expected words have been pre-activated previous to stimulus presentation. Second, we tested opposing theoretical proposals about the role of the medial orbitofrontal cortex (OFC): Either OFC may respond to the breach of expectation; or OFC is activated when the present stimulus matches the prediction. A significant interaction between word frequency and predictability indicated OFC responses to breaches of expectation for low- but not for high-frequency words: OFC is sensitive to both, bottom-up processing as mediated by word frequency, as well as top-down predictions. Particularly, when a rare word is unpredictable, OFC becomes active. Finally, we discuss how a high temporal resolution can help future studies to disentangle the hemodynamic responses of single trials in such an ultra-rapid event succession as naturally paced reading. PMID:24642288
Hofmann, Markus J; Dambacher, Michael; Jacobs, Arthur M; Kliegl, Reinhold; Radach, Ralph; Kuchinke, Lars; Plichta, Michael M; Fallgatter, Andreas J; Herrmann, Martin J
As the present technology of cancer treatment cannot cure the diseases, a prospective therapy, named 'systemic therapy', brings forth a new trend in cancer treatment. The aptamer-NASBA-based lab-on-a-chip (LOC) for systemic therapy was designed, fabricated and tested as an ultra-sensitive tool to monitor signaling molecular profiling in serum samples. The chip is divided into four parallel functional areas, corresponding to four groups of signaling molecules (i.e. hormones, neurotransmitters, cytokines and tumor biomarkers). The results can help doctors fully understand the body of patients. The chip is modeled on a 384-well microplate, which is completely compatible with common microplate readers in a biological laboratory. It can distinguish 24 signaling molecules in the same blood sample quantitatively and simultaneously. The chip was made of PDMS and silicon with a deposited gold layer, which was coated by aptamers before bonding; then, the LOC was operated by external valves and a vacuum pump. Its performance was demonstrated by detecting the presence of a synthetic peptide, GnRH (gonadotropin-releasing hormone) in artificial samples. The results indicated that the LOC has the potential to quantify traces of biomarkers even at subfemtomolar levels. Compared with our previous immuno-NASBA LOC, the aptamer-NASBA LOC showed an increased sensitivity and better repeatability. PMID:23365958
Zhao, Xinyan; Dong, Tao; Yang, Zhaochu; Karlsen, Haakon
Epistasis is a growing area of research in genome-wide studies, but the differences between alternative definitions of epistasis remain a source of confusion for many researchers. One problem is that models for epistasis are presented in a number of formats, some of which have difficult-to-interpret parameters. In addition, the relation between the different models is rarely explained. Existing software for testing epistatic interactions between single-nucleotide polymorphisms (SNPs) does not provide the flexibility to compare the available model parameterizations. For that reason we have developed an R package for investigating epistatic and penetrance models, Epi2Loc, to aid users who wish to easily compare, interpret, and utilize models for two-locus epistatic interactions. Epi2Loc facilitates research on SNP-SNP interactions by allowing the R user to easily convert between common parametric forms for two-locus interactions, generate data for simulation studies, and perform power analyses for the selected model with a continuous or dichotomous phenotype. The usefulness of the package for model interpretation and power analysis is illustrated using data on rheumatoid arthritis. PMID:24983251
Walters, Raymond K; Laurin, Charles; Lubke, Gitta H
Previous investigations of ITG and TEM/ETG turbulence using the reduced gyro-landau fluid code TGLF, and gyrokinetic code GYRO have predicted that in the linear ohmic confinement (LOC) regime in Alcator C-Mod the dilution of the main D ion species by low-Z impurities reduces the ion transport to experimentally observed levels. This analysis assumed an average impurity ion charge Zi= 8. Recent spectroscopic measurements of the impurity ion species in the LOC regime in C-Mod have shown that the average Zi is approximately 9, which at the measured Zeff values (2-4) results in a significant dilution (>10%) of the majority D ion species. By puffing in nitrogen while using a cryopump to keep the density constant, new experiments enabled us to lower Zi to values near 8, thus further increasing dilution. To account for the sensitivity of the turbulent transport on the density (Lne) and temperature (LTe) gradient scale lengths, recently we used TGYRO to improve the agreement between theory and the measurements. The results of such simulations will be presented.
Porkolab, M.; Ennever, P.; Reinke, M. L.; Rice, J.; Rost, C.; Tsujii, N.; Davis, E.; Ernst, D.; Fiore, C.; Greenwald, M.; Hubbard, A.; Hughes, J.; Marmar, E.; Candy, J.; Staebler, G. M.; Waltz, R.
Motivation: Subcellular localization is one aspect of protein function. Despite advances in high-throughput imaging, localization maps remain incomplete. Several methods accurately predict localization, but many challenges remain to be tackled. Results: In this study, we introduced a framework to predict localization in life's three domains, including globular and membrane proteins (3 classes for archaea; 6 for bacteria and 18 for eukaryota). The resulting method, LocTree2, works well even for protein fragments. It uses a hierarchical system of support vector machines that imitates the cascading mechanism of cellular sorting. The method reaches high levels of sustained performance (eukaryota: Q18=65%, bacteria: Q6=84%). LocTree2 also accurately distinguishes membrane and non-membrane proteins. In our hands, it compared favorably with top methods when tested on new data. Availability: Online through PredictProtein (predictprotein.org); as standalone version at http://www.rostlab.org/services/loctree2. Contact: firstname.lastname@example.org Supplementary Information: Supplementary data are available at Bioinformatics online.
Goldberg, Tatyana; Hamp, Tobias; Rost, Burkhard
Background A number of excellent results with the cementless titanium femoral component of the Mallory Head Total Hip Replacement have been published. Unfortunately, these excellent results have been counteracted by the poor performance of the cementless titanium acetabular components. In 1994, the HexLoc acetabular component was replaced with a second-generation design, the RingLoc. We hypothesized that the new generation would have improved the results. Methods We retrospectively studied 111 consecutive patients (150 hips) younger than 55 years. Median follow-up time was 14 (6–18) years for the HexLoc and 10 (1–14) years for the RingLoc. 7 patients were lost to follow-up and 7 patients died. The 10-year survival rate, radiographic liner wear, and radiographic signs of prosthesis failure were compared between the 2 acetabular components. Results The Kaplan-Meier survival estimate with revision for any reason as the endpoint showed a 10-year survival of 89% (95% CI: 81–97) for the HexLoc and 92% (CI: 85–98) for the RingLoc. The mean annual wear rate for the HexLoc was 0.16 (SD 0.16) mm and it was 0.15 (0.1) mm for the RingLoc (p = 0.3). The radiographic signs of failure were equally distributed between the 2 groups. Interpretation Compared to the HexLoc type, the RingLoc system did not improve the mean percentage survival at 10 years; nor did it reduce the liner wear. Despite correction of the known design flaws in the HexLoc design, the RingLoc system did not show a clinically relevant improvement compared to its predecessor.
Arachnoid granulation is often found incidentally in the dural sinuses and skull. It may also enlarge the dural sinus or inner table of the skull. We report a 46-year-old woman who presented with occipital headaches and arachnoid granulations in both transverse sinuses and torcular herophili. Neurological examination was normal. Fundoscopic examination, visual fields and acuity were normal. The headache resolved with medical treatment. No intervention for these lesions was planned. The patient was followed up with magnetic resonance imaging studies. PMID:23319230
Tural Emon, Selin; Orakdogen, Metin; Akpinar, Elif; Hakan, Tayfun; Zafer Berkman, Mehmet
Objective The optimal surgical approach for a trigone meningioma is still controversial. Here, we report two patients with trigone meningioma\\u000a treated successfully via an occipital inter-hemispheric and trans-cortical approach in the lateral semi-prone position.\\u000a \\u000a \\u000a \\u000a Clinical presentation A 53-year-old woman was admitted to a local hospital with sudden transient dizziness and vomiting. The CT brain scan demonstrated\\u000a a right intra-ventricular tumour. She was
Takafumi Nishizaki; Norio Ikeda; Shigeki Nakano; Tomomi Okamura; Seisho Abiko
Paintball is an "extreme sport" that has been steadily growing in popularity since the early 1980s. Although this activity is considered recreational, there are a number of inherent dangers associated. Most notably, the number of head and neck injuries due to paintball participation has been increasing in recent years. In this paper we present the first reported case of occipital artery traumatic pseudoaneurysm resulting from a paintball accident. The presentation, diagnosis and intraoperative findings are detailed. A discussion including a review of the literature is also presented. The authors recommend a re-evaluation of guidelines within the paintball sporting industry, including improvements in protective equipment. PMID:18922630
John, Neely; Leach, James L; Rachana, Tyagi; Mangano, Francesco T
Bilateral dermoid sinuses were identified on the parieto-occipital region of a Rottweiler. Diagnosis was confirmed by histological examination after successful complete surgical resection. The dermoid sinuses were independent with separate tracts. This unusual parasagittal location can be explained by craniofacial development: dermoid sinuses on the head could occur along the lines of embryological fusion and not only in the sagittal plane. A hypothesis of an origin at the level of the suture between the parietal and interparietal bones is possible in this case. PMID:17286665
Bornard, N; Pin, D; Carozzo, C
Cultural reshaping (artificial deformation or modification) of the neurocranial vault provides an artificially increased range of morphological variability within which the relationship between the growing neurocranium and face can be investigated. We analyze crania which have been fronto-occipitally compressed to ascertain possible morphological effects on the mandible. We collected measures of mandibular breadth, length, and height from 82 modified (N = 48) and unmodified (N = 34) crania from a Peruvian Ancon series. Angle classification was also scored in order to investigate whether or not occlusal relationships were affected by neurocranial reshaping. Only intercondylar distance (posterior mandibular breadth) exhibited significant differences between unmodified and modified groups, though this difference was relatively small compared with vault deformation. The modified crania had a higher frequency of normal occlusion (Class I) than the unmodified crania. Increased intercondylar breadth in modified skulls is due to a cascade of effects which begin with a direct effect of the fronto-occipital deforming device on neurocranial shape (increased neurocranial width). The increase in mandibular breadth may be a compensatory response to increased cranial base breadth and maintains articulation between the cranial base and mandible. The increased posterior breadth, coupled with a slight decrease in mandibular depth, may contribute to the change in occlusal relationships suggested for this sample. PMID:1543243
Cheverud, J M; Midkiff, J E
The deep-seated location of pineal parenchymal tumors (PPTs) and their associations with critical structures make their surgical resection technically challenging; further, the rarity of PPTs and repeated changes in their histopathological diagnostic criteria makes the study of their biological behavior and clinical outcomes difficult. Here, we describe the surgical techniques and results of an occipital transtentorial approach for PPTs together with the results in the clinicopathological study of PPTs. Since 1982, we have treated 93 patients with pineal region tumors, including 17 PPTs, with the occipital transtentorial approach using the lateral semiprone position. The infrasplenial approach is helpful in separating the internal cerebral veins from the tumor, particularly when the tumor is tightly adherent to the veins. Permanent homonymous hemianopsia occurred in 1 of the 17 patients with PPTs. Permanent ocular movement disorders were not encountered. Extensive removal of the tumor significantly prolongs survival at least in patients with pineocytomas and PPT of intermediate differentiation (PPTIMD). Despite extensive resection and adjuvant radiochemotherapy, the prognosis of the patients with pineoblastomas is extremely poor. Although the proliferative potentials of pineocytomas and PPTIMD were significantly lower than those of pineoblastomas, there was no such difference between pineocytomas and PPTIMD. PMID:19329859
Tsumanuma, Itaru; Tanaka, Ryuichi; Fujii, Yukihiko
We studied six children with ages ranging from 4 to 10 years who were affected by childhood epilepsy with occipital paroxysms and presented after a stormy onset with prolonged loss of consciousness for 6-14 h. In all these patients, seizures were preceded by visual symptoms in the form of colored circular disks. A CT scan was performed immediately after the onset of symptoms and was normal in all patients. Routine laboratory and cerebrospinal fluid examinations were normal in all patients. The interictal EEG was characterized by continuous or subcontinuous occipital spike wave discharges, which disappeared after the patients' eyes opened. We carried out a 7-year follow-up of all these patients. Only two patients were treated with antiepileptic drugs. The therapy (phenobarbital, clobazam) in the two patients did not induce changes in the EEG pattern. The first did not suffer any further seizures. The second patient had two more seizures (at 8 and 18 months from the onset) with phosphenes, confusional state, and involuntary movements followed by loss of consciousness. Among the other four patients, who did not receive any treatment, only one had any other seizures. The stormy onset of the syndrome described in our six patients emphasizes the extreme variability in the presentation of this type of childhood epilepsy. Our follow-up confirms the good prognosis of this epilepsy even when it has a stormy onset. PMID:10672427
Verrotti, A; Domizio, S; Melchionda, D; Guerra, M; Mucedola, T; Onofrj, M; Chiarelli, F; Sabatino, G
Predicting protein subcellular localization is an important and difficult problem, particularly when query proteins may have the multiplex character, i.e., simultaneously exist at, or move between, two or more different subcellular location sites. Most of the existing protein subcellular location predictor can only be used to deal with the single-location or “singleplex” proteins. Actually, multiple-location or “multiplex” proteins should not be ignored because they usually posses some unique biological functions worthy of our special notice. By introducing the “multi-labeled learning” and “accumulation-layer scale”, a new predictor, called iLoc-Euk, has been developed that can be used to deal with the systems containing both singleplex and multiplex proteins. As a demonstration, the jackknife cross-validation was performed with iLoc-Euk on a benchmark dataset of eukaryotic proteins classified into the following 22 location sites: (1) acrosome, (2) cell membrane, (3) cell wall, (4) centriole, (5) chloroplast, (6) cyanelle, (7) cytoplasm, (8) cytoskeleton, (9) endoplasmic reticulum, (10) endosome, (11) extracellular, (12) Golgi apparatus, (13) hydrogenosome, (14) lysosome, (15) melanosome, (16) microsome (17) mitochondrion, (18) nucleus, (19) peroxisome, (20) spindle pole body, (21) synapse, and (22) vacuole, where none of proteins included has pairwise sequence identity to any other in a same subset. The overall success rate thus obtained by iLoc-Euk was 79%, which is significantly higher than that by any of the existing predictors that also have the capacity to deal with such a complicated and stringent system. As a user-friendly web-server, iLoc-Euk is freely accessible to the public at the web-site http://icpr.jci.edu.cn/bioinfo/iLoc-Euk. It is anticipated that iLoc-Euk may become a useful bioinformatics tool for Molecular Cell Biology, Proteomics, System Biology, and Drug Development Also, its novel approach will further stimulate the development of predicting other protein attributes.
Chou, Kuo-Chen; Wu, Zhi-Cheng; Xiao, Xuan
Occipital stroke and occipital epilepsy are possible manifestations of mitochondrial diseases. A previous study in northern\\u000a Finland suggested a frequency of 10% for mitochondrial disorder in young patients with stroke. Here we studied the epidemiology\\u000a of occipital brain infarcts in a defined population in southwestern Finland. Patients diagnosed with brain infarct or visual\\u000a field defect with onset at the ages
Mika H. Martikainen; Kari Majamaa
The NMDA receptor antagonist ketamine can induce a rapid improvement in depressive symptoms that often endures for days after a single intravenous dose. The pharmacodynamic basis for this effect is poorly understood. Using a proton magnetic resonance spectroscopy ([1H]-MRS) method that previously detected a normalization of amino acid neurotransmitter (AANt) content after chronic treatment with conventional antidepressant treatments, we examined whether the acute action of ketamine is associated with alterations in AANt content as well. Ten subjects with major depressive disorder (MDD) received saline, then ketamine in a fixed order, one week apart, under single-blind conditions. Each infusion was associated with three [1H] MRS scans (baseline, 3 hours and 48 hours post-infusion) that measured glutamate, GABA and glutamine within the occipital cortex. Rating scales were administered before, during and after each infusion. The rapid (1 hour) and sustained (at least 7 days) antidepressant effect we observed after ketamine infusion was not associated with either baseline measures of, or changes in, occipital AANt content. Dissociative symptoms were not correlated with changes in depression scores. While our results indicate that changes in occipital AANt content are not a correlate of ketamine’s antidepressant action, this may only apply to the regional and temporal windows of our MRS measurements.
Valentine, Gerald W.; Mason, Graeme F.; Gomez, Rosane; Fasula, Madonna; Watzl, June; Pittman, Brian; Krystal, John H.; Sanacora, Gerard
The Lockne crater is a 456 Ma old marine-target impact structure. It has a 7,5km wide inner crater developed in the crystalline basement, which is surrounded by a 3,5km wide brim where the crater excavation removed most of sedimentary cover rocks (mainly limestone and dark shale) before it was covered by the ejecta flap from the basement crater. The crystalline rocks of the basement are mainly granitoids, but several tens of meters thick dolerite sills are included. Here, we provide a precise analysis of the rock magnetic properties from the LOC-9 core. This is a 31,04m long and 42mm in diameter core drilled into the crystalline crater brim and ejecta flap. Thus, it provides an excellent opportunity to study the process of flap formation.
Melero Asensio, I.; Martín-Hernández, F.; Ormö, J.
We have found that pulse wave delay increases linearly with +Gz experienced by conscious subjects and that G-tolerance limits, as measured using conventional light bars, occur repeatedly at the same pulse wave delays or delta delay. When protective modalities such as anti-G suits or supinating seats are used, the delta delays increase at a slower rate as a function of +Gz. G-tolerance thresholds occur at higher +Gz levels with protection but the delta pulse wave delays reach the same value for all tolerance levels. This parameter can be used to warn expert systems of the approach of G-LOC during actual flight and/or provides an objective measure of G protection provided by new or modified anti-G equipment. Therefore, this tool can be used in the research setting to evaluate the efficacy of G-protective equipment in an objective manner. PMID:3355462
Twelve normal subjects viewed alternating sequences of unfa- miliar faces, unpronounceable nonword letterstrings, and tex- tures while echoplanar functional magnetic resonance images were acquired in seven slices extending from the posterior margin of the splenium to near the occipital pole. These stimuli were chosen to elicit initial category-specific processing in extrastriate cortex while minimizing semantic processing. Over- all, faces evoked
Aina Puce; Truett Allison; Maryam Asgari; John C. Gore; Gregory McCarthy
Background Occipital condyle fractures (OCF) are rare traumatic injuries and are of critical clinical importance because of the anatomic considerations of the occipitoatlantoaxial joint complex. OCF can be a diagnostic challenge because of the inability to diagnose this injury with plain radiographs. This is especially true in the emergency department (ED) setting. A high degree of clinical suspicion and careful investigation of the craniocervical junction is warranted in patients presenting to the ED with head and cervical trauma. Findings We present a case of a 45-year-old male who presented to the ED with complaints of neck pain and headache four days after an assault. The classification, clinical presentation, diagnosis, and management of his injury are discussed, and pertinent literature is reviewed. Conclusions OCF can be easily overlooked due to multiple factors; including the conscious state of the patient or the inability to diagnose it through plain radiographs. Early recognition and diagnosis of OCF is crucial to prevent neurological involvement.
A 20 year old girl presented with a history of neck and occipital pain for six weeks, which was found to be due to a unicameral bone cyst of the left occipital condylar region. The differential diagnosis of bone cysts in the skull is discussed. Six months after the operation, the patient again presented with backache due to adhesive arachnoiditis.
W. G. Bradley; R. M. Kalbag; P. S. Ramani; B. E. Tomlinson
Purpose Age-related macular degeneration (AMD) is a multi-factorial blinding disease in the elderly. LOC387715 harbors a single-nucleotide polymorphism that has an association with AMD. This study was conducted to confirm the association between LOC387715 and AMD and to refine estimates of the impact of this gene variation in using samples from three studies: an Australian population-based study and two U.S. clinic-based case-control studies. Methods Cases and controls were collected from a National Eye Institute (NEI) clinical protocol (n = 240), the Age-Related Eye Disease Study (AREDS; n = 488), and the Blue Mountains Eye Study (BMES; n = 851). After DNA extraction, subjects were genotyped for the LOC387715 Ala69Ser polymorphism (rs10490924). Results The combined NEI and AREDS samples yielded odds ratios (ORs) of 2.61 (95% CI 1.89–3.61, P = 1.42 × 10?9) and 8.59 (95% CI 4.49–16.5, P = 3.56 × 10?13) for the heterozygous and homozygous risk alleles, respectively. The corresponding odds ratios in the BMES sample were 1.69 (95% CI: 1.25–2.28, P = 0.0007) and 2.20 (95% CI: 1.05–4.62, P = 0.038) for the heterozygous and homozygous groups. Neither set of samples showed statistically significant interaction with smoking, although there appeared to be a trend of interaction between smoking and LOC387715 for risk of advanced AMD. Conclusions Although these data from three case-control samples support an AMD genetic risk marker harbored within LOC387715, the nested case-control data from the population-based BMES samples showed lower estimates than from the clinic-based samples. This may be because the BMES samples consisted of largely early AMD cases while the clinic-based AMD samples consisted exclusively of advanced cases.
Ross, Robert J.; Bojanowski, Christine M.; Wang, Jie Jin; Chew, Emily Y.; Rochtchina, Elena; Ferris, Frederick L.; Mitchell, Paul; Chan, Chi-Chao; Tuo, Jingsheng
Subcellular localization is a key functional characteristic of proteins. It is determined by signals encoded in the protein sequence. The experimental determination of subcellular localization is laborious. Thus, a number of computational methods have been developed to predict the protein location from sequence. However predictions made by different methods often disagree with each other and it is not always clear which algorithm performs best for the given cellular compartment. We benchmarked primary subcellular localization predictors for proteins from Gram-negative bacteria, PSORTb3, PSLpred, CELLO, and SOSUI-GramN, on a common dataset that included 1056 proteins. We found that PSORTb3 performs best on the average, but is outperformed by other methods in predictions of extracellular proteins. This motivated us to develop a meta-predictor, which combines the primary methods by using the logistic regression models, to take advantage of their combined strengths, and to eliminate their individual weaknesses. MetaLocGramN runs the primary methods, and based on their output classifies protein sequences into one of five major localizations of the Gram-negative bacterial cell: cytoplasm, plasma membrane, periplasm, outer membrane, and extracellular space. MetaLocGramN achieves the average Matthews correlation coefficient of 0.806, i.e. 12% better than the best individual primary method. MetaLocGramN is a meta-predictor specialized in predicting subcellular localization for proteins from Gram-negative bacteria. According to our benchmark, it performs better than all other tools run independently. MetaLocGramN is a web and SOAP server available for free use by all academic users at the URL http://iimcb.genesilico.pl/MetaLocGramN. This article is part of a Special Issue entitled: Computational Methods for Protein Interaction and Structural Prediction. PMID:22705560
Magnus, Marcin; Pawlowski, Marcin; Bujnicki, Janusz M
Individuals using a visual-to-auditory sensory substitution device (SSD) called 'The vOICe' can identify objects in their environment through images encoded by sound. We have shown that identifying objects with this SSD is associated with activation of occipital visual areas. Here, we show that repetitive transcranial magnetic stimulation (rTMS) delivered to a specific area of occipital cortex (identified by functional MRI) profoundly impairs a blind user's ability to identify objects. rTMS delivered to the same site had no effect on a visual imagery task. The task and site-specific disruptive effect of rTMS in this individual suggests that the cross-modal recruitment of occipital visual areas is functional in nature and critical to the patient's ability to process and decode the image sounds using this SSD. PMID:19104453
Merabet, Lotfi B; Battelli, Lorella; Obretenova, Souzana; Maguire, Sara; Meijer, Peter; Pascual-Leone, Alvaro
Dementia with Lewy bodies (DLB) is often associated with occipital hypometabolism or hypoperfusion, as well as deficits in cholinergic neurotransmission. In this study, 11 mild DLB, 16 mild AD and 16 age-matched controls underwent arterial spin-labeled perfusion MRI (ASL-pMRI) and neuropsychological testing. Patterns of cerebral blood flow (CBF) and cognitive performance were compared. In addition, combined ASL-pMRI and ChEI drug challenge (pharmacologic MRI) was tested as a probe of cholinergic function in 4 of the DLB participants. Frontal and parieto-occipital hypoperfusion was observed in both DLB and AD but was more pronounced in DLB. Following ChEI treatment, perfusion increased in temporal and parieto-occipital cortex, and cognitive performance improved on a verbal fluency task. If confirmed in a larger study, these results provide further evidence for brain cholinergic dysfunction in DLB pathophysiology, and use of pharmacologic MRI as an in vivo measure of cholinergic function.
Inouye, Sharon K.; Dai, Weiying; Press, Daniel Z.; Alsop, David C.
Occipital nerve stimulation (ONS) is a form of peripheral nerve stimulation used to treat refractory headaches. The trial of ONS was carried with the midline incision C1-2 level, inserted electrical lead subcutaneously to oblique and cephalad direction followed by trajectory of blunt dissection. We used 8 pole electrical lead to cover lesser occipital nerve, greater occipital nerve, third occipital nerve and great auricular nerve. We anchored the lead at the midline insertion site after confirming the stimulation of the patient. And then we looped and tightened the lead loosely, connected the lead and the extension under right supraspinatus muscle region. After 1 week trial period, we performed the permanent implantation of occipital nerve stimulator. We inserted internal pulse generator under a pocket located at right infraclavicular region. The VAS score dropped from 8/10 to 1-2/10. No serious complications were detected during 1 month follow-up.
Shin, Jae Hyuck; Jang, In Ki; Kim, Jae-Hun; Park, Soo Young; Lee, Sang Chul
The human cerebral cortex appears to shrink during adolescence. To delineate the dynamic morphological changes involved in this process, 52 healthy male and female adolescents (11-17 years old) were neuroimaged twice using magnetic resonance imaging, approximately 2 years apart. Using a novel morphometric analysis procedure combining the FreeSurfer and BrainVisa image software suites, we quantified global and lobar change in cortical thickness, outer surface area, the gyrification index, the average Euclidean distance between opposing sides of the white matter surface (gyral white matter thickness), the convex ("exposed") part of the outer cortical surface (hull surface area), sulcal length, depth, and width. We found that the cortical surface flattens during adolescence. Flattening was strongest in the frontal and occipital cortices, in which significant sulcal widening and decreased sulcal depth co-occurred. Globally, sulcal widening was associated with cortical thinning and, for the frontal cortex, with loss of surface area. For the other cortical lobes, thinning was related to gyral white matter expansion. The overall flattening of the macrostructural three-dimensional architecture of the human cortex during adolescence thus involves changes in gray matter and effects of the maturation of white matter. PMID:24048830
Alemán-Gómez, Yasser; Janssen, Joost; Schnack, Hugo; Balaban, Evan; Pina-Camacho, Laura; Alfaro-Almagro, Fidel; Castro-Fornieles, Josefina; Otero, Soraya; Baeza, Immaculada; Moreno, Dolores; Bargalló, Nuria; Parellada, Mara; Arango, Celso; Desco, Manuel
One of the most intriguing findings on language comprehension is that violations of syntactic predictions can affect event-related potentials as early as 120 ms, in the same time-window as early sensory processing. This effect, the so-called early left-anterior negativity (ELAN), has been argued to reflect word category access and initial syntactic structure building (Friederici, 2002). In two experiments, we used magnetoencephalography to investigate whether (a) rapid word category identification relies on overt category-marking closed-class morphemes and (b) whether violations of word category predictions affect modality-specific sensory responses. Participants read sentences containing violations of word category predictions. Unexpected items varied in whether or not their word category was marked by an overt function morpheme. In Experiment 1, the amplitude of the visual evoked M100 component was increased for unexpected items, but only when word category was overtly marked by a function morpheme. Dipole modeling localized the generator of this effect to the occipital cortex. Experiment 2 replicated the main results of Experiment 1 and eliminated two non-morphology-related explanations of the M100 contrast we observed between targets containing overt category-marking and targets that lacked such morphology. Our results show that during reading, syntactically relevant cues in the input can affect activity in occipital regions at around 125 ms, a finding that may shed new light on the remarkable rapidity of language processing.
Dikker, Suzanne; Rabagliati, Hugh; Pylkkanen, Liina
Combining transcranial magnetic stimulation (TMS) with concurrent functional magnetic resonance imaging (fMRI) allows study of how local brain stimulation may causally affect activity in remote brain regions. Here, we applied bursts of high- or low-intensity TMS over right posterior parietal cortex, during a task requiring sustained covert visuospatial attention to either the left or right hemifield, or in a neutral control condition, while recording blood oxygenation-level–dependent signal with a posterior MR surface coil. As expected, the active attention conditions activated components of the well-described “attention network,” as compared with the neutral baseline. Also as expected, when comparing left minus right attention, or vice versa, contralateral occipital visual cortex was activated. The critical new finding was that the impact of high- minus low-intensity parietal TMS upon these visual regions depended on the currently attended side. High- minus low-intensity parietal TMS increased the difference between contralateral versus ipsilateral attention in right extrastriate visual cortex. A related albeit less pronounced pattern was found for left extrastriate visual cortex. Our results confirm that right human parietal cortex can exert attention-dependent influences on occipital visual cortex and provide a proof of concept for the use of concurrent TMS–fMRI in studying how remote influences can vary in a purely top–down manner with attentional demands.
Ruff, Christian C.; Bestmann, Sven; Bjoertomt, Otto; Josephs, Oliver; Deichmann, Ralf; Driver, Jon
Neuroimaging studies have identified a face-selective region in the right posterior superior temporal sulcus (rpSTS) that responds more strongly during facial expression recognition tasks than during facial identity recognition tasks, but precisely when the rpSTS begins to causally contribute to expression recognition is unclear. The present study addressed this issue using transcranial magnetic stimulation (TMS). In Experiment 1, repetitive TMS delivered over the rpSTS of human participants, at a frequency of 10 Hz for 500 ms, selectively impaired a facial expression task but had no effect on a matched facial identity task. In Experiment 2, participants performed the expression task only while double-pulse TMS (dTMS) was delivered over the rpSTS or over the right occipital face area (rOFA), a face-selective region in lateral occipital cortex, at different latencies up to 210 ms after stimulus onset. Task performance was selectively impaired when dTMS was delivered over the rpSTS at 60-100 ms and 100-140 ms. dTMS delivered over the rOFA impaired task performance at 60-100 ms only. These results demonstrate that the rpSTS causally contributes to expression recognition and that it does so over a longer time-scale than the rOFA. This difference in the length of the TMS induced impairment between the rpSTS and the rOFA suggests that the neural computations that contribute to facial expression recognition in each region are functionally distinct. PMID:24990937
We studied patient JS, who had a right occipital infarct that encroached on visual areas V1, V2v, and VP. When tested psychophysically, he was very impaired at detecting the direction of motion in random dot displays where a variable proportion of dots moving in one direction (signal) were embedded in masking motion noise (noise dots). The impairment on this motion coherence task was especially marked when the display was presented to the upper left (affected) visual quadrant, contralateral to his lesion. However, with extensive training, by 11 months his threshold fell to the level of healthy participants. Training on the motion coherence task generalized to another motion task, the motion discontinuity task, on which he had to detect the presence of an edge that was defined by the difference in the direction of the coherently moving dots (signal) within the display. He was much better at this task at 8 than 3 months, and this improvement was associated with an increase in the activation of the human MT complex (hMT(+)) and in the kinetic occipital region as shown by repeated fMRI scans. We also used fMRI to perform retinotopic mapping at 3, 8, and 11 months after the infarct. We quantified the retinotopy and areal shifts by measuring the distances between the center of mass of functionally defined areas, computed in spherical surface-based coordinates. The functionally defined retinotopic areas V1, V2v, V2d, and VP were initially smaller in the lesioned right hemisphere, but they increased in size between 3 and 11 months. This change was not found in the normal, left hemisphere of the patient or in either hemispheres of the healthy control participants. We were interested in whether practice on the motion coherence task promoted the changes in the retinotopic maps. We compared the results for patient JS with those from another patient (PF) who had a comparable lesion but had not been given such practice. We found similar changes in the maps in the lesioned hemisphere of PF. However, PF was only scanned at 3 and 7 months, and the biggest shifts in patient JS were found between 8 and 11 months. Thus, it is important to carry out a prospective study with a trained and untrained group so as to determine whether the patterns of reorganization that we have observed can be further promoted by training. PMID:24345177
Vaina, Lucia M; Soloviev, Sergei; Calabro, Finnegan J; Buonanno, Ferdinando; Passingham, Richard; Cowey, Alan
Lesions located in the bilateral posterior incisural space are difficult to treat due to limited exposure. The classical approaches to this area are limited for lesions located bilaterally and especially when the lesion extends also below the tentorium as it may occur with meningiomas. Kawashima et al. reported, in anatomic studies, a new occipital transtentorial approach: the occipital bi-transtentorial/falcine approach, to treat such lesions. We present a patient with a large falcotentorial meningioma, located bilaterally in the posterior incisural space. The occipital bi-transtentorial/falcine approach allowed an excellent surgical exposure and complete tumor removal with an excellent patient outcome. PMID:16622571
Gusmão, Sebastião; Oliveira, Marcelo Magaldi; Arantes, Aluízio; Ulhoa, Tales Henrique; Morato, Eric Grossi
Atlanto-occipital assimilation is one of the most common osseous anomalies observed at the craniocervical junction. Most patients with atlas assimilation show no symptom, but some have neurological problems such as myelopathy that may require surgical treatment. Occipitocervical fusion may be required if atlato-occipital assimilation is accompanied by occipito-axial instability. However, in cases of symptomatic atlas assimilation with minor cord compression without instability, simple decompressive surgery may be the treatment modality. This report describes a case of successful treatment of a patient with myelopathy secondary to atlanto-occipital assimilation without instability, using posterior simple decompressive surgery. PMID:24757486
Kim, Kang Rae; Lee, Young Min; Kim, Young Zoon; Cho, Yong Woon; Kim, Joon Soo; Kim, Kyu Hong; Lee, In Chang
Atlanto-occipital assimilation is one of the most common osseous anomalies observed at the craniocervical junction. Most patients with atlas assimilation show no symptom, but some have neurological problems such as myelopathy that may require surgical treatment. Occipitocervical fusion may be required if atlato-occipital assimilation is accompanied by occipito-axial instability. However, in cases of symptomatic atlas assimilation with minor cord compression without instability, simple decompressive surgery may be the treatment modality. This report describes a case of successful treatment of a patient with myelopathy secondary to atlanto-occipital assimilation without instability, using posterior simple decompressive surgery.
Kim, Kang Rae; Kim, Young Zoon; Cho, Yong Woon; Kim, Joon Soo; Kim, Kyu Hong; Lee, In Chang
Quasar broad lines exhibit several trends, including the Baldwin effect, an anticorrelation between the emission line equivalent width and continuum luminosity. There is suggestive evidence that the Baldwin effect is driven by the spectral energy distribution (SED). We test this assertion and the efficacy of the locally-optimally-emitting cloud (LOC) model using large-scale Cloudy modeling. We investigate the effect of the SED by constructing a grid of continua in which ?ox and the temperature of the UV cutoff are varied independently. We also vary the LOC radial- and density-distribution indices. We constrain the results using three sets of results: the relationship between ?ox and CIV equivalent width observed by Wu et al. 2009, the relationship between luminosity and ?ox parameterized by Just et al. 2007, and the Baldwin effect results from 19 lines measured in luminosity-sorted quasar composite spectra by Dietrich et al. 2002. We investigate the baseline LOC (column density log(NH)=23.5) as well as high column density log(NH)=24.5, enhanced abundances (Z=5), and alternative SEDs that have a power law in the EUV rather than an exponential cutoff. Our preliminary results show that, for the baseline model, the Baldwin effect is explained by a softening of the SED as well as a decrease of the covering fraction at higher luminosities. The radial and density indices are independent of luminosity and lie near the standard values of -1 and -1. In contrast, the high column model explains the Baldwin effect principally as a softening of the SED with no trend in covering fraction. Both the high metallicity and alternative SED models provide poorer fits. The LOC fails to model some emission lines well, and some evidence for two zones is found. Additional results will be described. This work is funded by NSF AST-0707703.
Leighly, Karen; Hemantha, M. D. P.; Richards, G.
Purpose BH3-like motif containing, cell death inducer (BLID) and LOC399959 are two genes associated with the single nucleotide polymorphism (SNP) rs577948, which is a susceptibility locus for high myopia in Japanese subjects. The purpose of this study was to determine if BLID and LOC399959 are associated with high myopia in Chinese Han subjects. Methods High myopia subjects (n=476) had a spherical refractive error of less than ?6.00 D in at least one eye and/or an axial length greater than 26 mm. Genomic DNA was extracted and genotyped from peripheral blood leukocytes of high myopes and controls (n=275). Using a case-control association study of candidate regions, linkage disequilibrium blocks for 19 tag SNPs (tSNPs), including rs577948, harbored within and surrounding the BLID and LOC399959 genes were analyzed on a MassArray platform using iPlex chemistry. Each of the tSNPs had an r2>0.8 and minor allele frequency >10% in the Chinese Han population. Haplotype association analysis was performed on Haploview 4.1 using Chi-square (?2) tests. Results None of the 19 tSNPs were statistically associated with high myopia. Conclusions While rs577948 may be associated with high myopia in Japanese subjects, it and the other tSNPs near the BLID and LOC399959 genes are not susceptibility loci for high myopia in the Chinese Han population. Thus, associations of SNPs with high myopia as determined by Genome-Wide Association Study (GWAS) may be restricted to certain ethnic or genetically distinct populations. Without systematic replication in other populations, the results of GWAS associations should be interpreted with great caution.
Zhao, Fuxin; Bai, Jian; Chen, Wei; Xue, Anquan; Li, Chaohua; Yan, Zhonghui; Chen, Hui; Lu, Fan; Hu, Yongwu; Qu, Jia; Zeng, Changqing
In this paper, we present a novel, ultra-long-time- constant analogue integrator for a PID controller in Lab-on- Chip (LOC) applications. A time constant of up to 5 seconds is achievable using a capacitance of only 18pF by exploiting transconductance reduction techniques involving current splitting and gm-attenuated OTA. Additionally, this architecture provides the ability to digitally tune the time constant from
Yuanqi Hu; Yan Liu; Timothy G. Constandinou; Christofer Toumazou
The Freiburg RNA tools web server integrates three tools for the advanced analysis of RNA in a common web-based user interface. The tools IntaRNA, ExpaRNA and LocARNA support the prediction of RNA–RNA interaction, exact RNA matching and alignment of RNA, respectively. The Freiburg RNA tools web server and the software packages of the stand-alone tools are freely accessible at http://rna.informatik.uni-freiburg.de.
Smith, Cameron; Heyne, Steffen; Richter, Andreas S.; Will, Sebastian; Backofen, Rolf
Neurophysiology and neuroimaging research implicates distinct regions of posterior parietal cortex for reaching versus grasping\\u000a and for completing these movements in central versus peripheral space. Typically, visuomotor tasks only examine movements\\u000a made in the frontoparallel plane. We examined a patient with a right superior parietal lesion encompassing the parietal-occipital\\u000a junction, the intraparietal sulcus and the putative human homologue of V6A
James Danckert; Lana Goldberg; Carol Broderick
The representation of the visual field in early visual areas is retinotopic. The point-to-point relationship on the retina is therefore maintained on the convoluted cortical surface. Functional magnetic resonance imaging (fMRI) has been able to demonstrate the retinotopic representation of the visual field in occipital cortex of normal subjects. Furthermore, visual areas that are retinotopic can be identified on computationally
Antony B. Morland; Heidi A. Baseler; Michael B. Hoffmann; Lindsay T. Sharpe; Brian A. Wandell
Purpose: Children with medulloblastoma undergo surgery, radiotherapy, and chemotherapy. After treatment, these children have numerous structural abnormalities. Using high-resolution magnetic resonance imaging, we measured the thickness of the cerebral cortex in a group of medulloblastoma patients and a group of normally developing children. Methods and Materials: We obtained magnetic resonance imaging scans and measured the cortical thickness in 9 children after treatment of medulloblastoma. The measurements from these children were compared with the measurements from age- and gender-matched normally developing children previously scanned. For additional comparison, the pattern of thickness change was compared with the cortical thickness maps from a larger group of 65 normally developing children. Results: In the left hemisphere, relatively thinner cortex was found in the perirolandic region and the parieto-occipital lobe. In the right hemisphere, relatively thinner cortex was found in the parietal lobe, posterior superior temporal gyrus, and lateral temporal lobe. These regions of cortical thinning overlapped with the regions of cortex that undergo normal age-related thinning. Conclusion: The spatial distribution of cortical thinning suggested that the areas of cortex that are undergoing development are more sensitive to the effects of treatment of medulloblastoma. Such quantitative methods may improve our understanding of the biologic effects that treatment has on the cerebral development and their neuropsychological implications.
Liu, Arthur K. [Harvard Combined Radiation Oncology Program, Harvard Medical School, Boston, MA (United States)]. E-mail: email@example.com; Marcus, Karen J. [Department of Radiation Oncology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Department of Radiation Oncology, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Department of Radiation Oncology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (United States); Fischl, Bruce [Athinoula A. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA (United States); Department of Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Division of Health Sciences and Technology, Cambridge, MA (United States); Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Young Poussaint, Tina [Department of Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Rivkin, Michael J. [Departments of Neurology, Psychiatry, and Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Davis, Peter [Departments of Neurology, Psychiatry, and Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Yock, Torunn I. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States)
Classical fiber dissection of post mortem human brains enables us to isolate a fiber tract by removing the cortex and overlying white matter. In the current work, a modification of the dissection methodology is presented that preserves the cortex and the relationships within the brain during all stages of dissection, i.e. ‘cortex-sparing fiber dissection’. Thirty post mortem human hemispheres (15 right side and 15 left side) were dissected using cortex-sparing fiber dissection. Magnetic resonance imaging study of a healthy brain was analyzed using diffusion tensor imaging (DTI)-based tractography software. DTI fiber tract reconstructions were compared with cortex-sparing fiber dissection results. The fibers of the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) were isolated so as to enable identification of their cortical terminations. Two segments of the SLF were identified: first, an indirect and superficial component composed of a horizontal and vertical segment; and second, a direct and deep component or arcuate fasciculus. The IFOF runs within the insula, temporal stem and sagittal stratum, and connects the frontal operculum with the occipital, parietal and temporo-basal cortex. The UF crosses the limen insulae and connects the orbito-frontal gyri with the anterior temporal lobe. Finally, a portion of the ILF was isolated connecting the fusiform gyrus with the occipital gyri. These results indicate that cortex-sparing fiber dissection facilitates study of the 3D anatomy of human brain tracts, enabling the tracing of fibers to their terminations in the cortex. Consequently, it is an important tool for neurosurgical training and neuroanatomical research.
Martino, Juan; De Witt Hamer, Philip C; Vergani, Francesco; Brogna, Christian; de Lucas, Enrique Marco; Vazquez-Barquero, Alfonso; Garcia-Porrero, Juan A; Duffau, Hugues
Occipital condyle fractures are rarely reported in the Emergency Medicine literature. It is unclear whether these fractures are rare or under-diagnosed. Occipital condyle fractures are associated with high-energy blunt trauma with significant cranial-cervical torque or axial loading. We report a case of a female patient with an occipital condyle fracture. The patient only complained of shoulder pain, but was found to have high cervical spine tenderness, after a moderate-speed front-end motor vehicle collision. Initial cervical spine radiographs were non-diagnostic. Computed tomography of the cervical spine demonstrated a non-displaced occipital condyle fracture. Conservative management with a semi-rigid cervical collar was successful in treating this patient's fracture. A review of the literature covers the diagnosis, radiographic findings, and management of this fracture. PMID:16982357
Mowafi, Hani O; Hickey, Kenneth S
An 11-year-old girl who had been given antiepileptic drugs (AEDs) for occipital lobe epilepsy was hospitalized with alternative psychosis and dysgraphia accompanied by forced normalization of the EEG. Her epileptic seizures and psychosis disappeared after administration of carbamazepine. She developed dysgraphia for Kanji words (Japanese morphograms). The EEG showed sporadic spikes predominantly in the left occipital region, and [123I]iomazenil single-photon-emission computed tomography (IMZ-SPECT) imaging revealed an area of hypoperfusion in the left occipital lobe. Interestingly, the left posterior inferior temporal area is known to play an important role in writing Kanji words. It is assumed that abnormal discharges in the left occipital lobe were projected into the left posterior inferior temporal area and that a functional disorder in that area led to dysgraphia; however, further exploration is needed. PMID:18182329
Hirashima, Yoshifumi; Morimoto, Masafumi; Nishimura, Akira; Osamura, Toshio; Sugimoto, Tohru
Background Most subjects with logopenic primary progressive aphasia (lvPPA) have beta-amyloid (A?) deposition on Pittsburgh Compound B PET (PiB-PET), usually affecting prefrontal and temporoparietal cortices, with less occipital involvement. Objectives To assess clinical and imaging features in lvPPA subjects with unusual topographic patterns of A? deposition with highest uptake in occipital lobe. Methods Thirty-three lvPPA subjects with A? deposition on PiB-PET were included in this case-control study. Line-plots of regional PiB uptake were created, including frontal, temporal, parietal and occipital regions, for each subject. Subjects in which the line sloped downwards in occipital lobe (lvPPA-low), representing low uptake, were separated from those where the line sloped upwards in occipital lobe (lvPPA-high), representing unusually high occipital uptake compared to other regions. Clinical variables, atrophy on MRI, hypometabolism on F18-fluorodeoxyglucose PET, and presence and distribution of microbleeds and white matter hyperintensities (WMH) were assessed. Results Seventeen subjects (52%) were classified as lvPPA-high. Mean occipital PiB uptake in lvPPA-high was higher than all other regions, and higher than all regions in lvPPA-low. The lvPPA-high subjects performed more poorly on cognitive testing, including executive and visuospatial testing, but the two groups did not differ in aphasia severity. Proportion of microbleeds and WMH was higher in lvPPA-high than lvPPA-low. Parietal hypometabolism was greater in lvPPA-high than lvPPA-low. Conclusions Unusually high occipital A? deposition is associated with widespread cognitive impairment and different imaging findings in lvPPA. These findings help explain clinical heterogeneity in lvPPA, and suggest that A? influences severity of overall cognitive impairment but not aphasia.
Whitwell, Jennifer L.; Lowe, Val J.; Duffy, Joseph R.; Strand, Edythe A.; Machulda, Mary M.; Kantarci, Kejal; Wille, Samantha M.; Senjem, Matthew L.; Murphy, Matthew C.; Gunter, Jeffrey L.; Jack, Clifford R.; Josephs, Keith A.
Osteoblastoma is an infrequent benign tumor and skull involvement is extremely rare. The occipital bone is much less frequently involved. We report an unusual case of a huge occipital osteoblastoma with aneurysmal bone cyst in the posterior cranial fossa of a 20-year-old young man. MRI scan and CT three-dimensional reconstruction revealed that the tumor (approximately 8.5cm×6cm×5cm) occupied nearly half volume
Xi Han; Yan Dong; Kehua Sun; Yicheng Lu
Charles Bonnet syndrome is an underrecognized disease that involves visual hallucinations in visually impaired patients. We present the cases of three patients who experienced complex visual hallucinations following various pathomechanisms. In two cases, diagnosis showed coexistence of occipital lobe damage with ocular damage, while in the third case it showed occipital lobe damage with retrobulbar optic neuritis. Theories of pathogenesis and the neuroanatomical basis of complex visual hallucinations are discussed and supported by literature review. PMID:24376461
Paradowski, Bogus?aw; Kowalczyk, Edyta; Chojdak-?ukasiewicz, Justyna; Loster-Niewi?ska, Aleksandra; S?u?ewska-Nied?wied?, Monika
Charles Bonnet syndrome is an underrecognized disease that involves visual hallucinations in visually impaired patients. We present the cases of three patients who experienced complex visual hallucinations following various pathomechanisms. In two cases, diagnosis showed coexistence of occipital lobe damage with ocular damage, while in the third case it showed occipital lobe damage with retrobulbar optic neuritis. Theories of pathogenesis and the neuroanatomical basis of complex visual hallucinations are discussed and supported by literature review.
Paradowski, Boguslaw; Kowalczyk, Edyta; Chojdak-Lukasiewicz, Justyna; Sluzewska-Niedzwiedz, Monika
Background Gene Ontology (GO) annotation, which describes the function of genes and gene products across species, has recently been used to predict protein subcellular and subnuclear localization. Existing GO-based prediction methods for protein subcellular localization use the known accession numbers of query proteins to obtain their annotated GO terms. An accurate prediction method for predicting subcellular localization of novel proteins without known accession numbers, using only the input sequence, is worth developing. Results This study proposes an efficient sequence-based method (named ProLoc-GO) by mining informative GO terms for predicting protein subcellular localization. For each protein, BLAST is used to obtain a homology with a known accession number to the protein for retrieving the GO annotation. A large number n of all annotated GO terms that have ever appeared are then obtained from a large set of training proteins. A novel genetic algorithm based method (named GOmining) combined with a classifier of support vector machine (SVM) is proposed to simultaneously identify a small number m out of the n GO terms as input features to SVM, where m <
Huang, Wen-Lin; Tung, Chun-Wei; Ho, Shih-Wen; Hwang, Shiow-Fen; Ho, Shinn-Ying
Blind individuals do not necessarily receive more auditory stimulation than sighted individuals. However, to interact effectively with their environment, they have to rely on non-visual cues (in particular auditory) to a greater extent. Often benefiting from cerebral reorganization, they not only learn to rely more on such cues but also may process them better and, as a result, demonstrate exceptional abilities in auditory spatial tasks. Here we examine the effects of blindness on brain activity, using positron emission tomography (PET), during a sound-source discrimination task (SSDT) in both early- and late-onset blind individuals. This should not only provide an answer to the question of whether the blind manifest changes in brain activity but also allow a direct comparison of the two subgroups performing an auditory spatial task. The task was presented under two listening conditions: one binaural and one monaural. The binaural task did not show any significant behavioural differences between groups, but it demonstrated striate and extrastriate activation in the early-blind groups. A subgroup of early-blind individuals, on the other hand, performed significantly better than all the other groups during the monaural task, and these enhanced skills were correlated with elevated activity within the left dorsal extrastriate cortex. Surprisingly, activation of the right ventral visual pathway, which was significantly activated in the late-blind individuals during the monaural task, was negatively correlated with performance. This suggests the possibility that not all cross-modal plasticity is beneficial. Overall, our results not only support previous findings showing that occipital cortex of early-blind individuals is functionally engaged in spatial auditory processing but also shed light on the impact the age of onset of blindness can have on the ensuing cross-modal plasticity. PMID:18234523
Voss, Patrice; Gougoux, Frederic; Zatorre, Robert J; Lassonde, Maryse; Lepore, Franco
Neuroscientists have long debated whether focal brain regions perform specific cognitive functions [1-5], and the issue remains central to a current debate about visual object recognition. The distributed view of cortical function suggests that object discrimination depends on dispersed but functionally overlapping representations spread across visual cortex [6-8]. The modular view claims different categories of objects are discriminated in functionally segregated and specialized cortical areas [9-11]. To test these competing theories, we delivered transcranial magnetic stimulation (TMS) over three adjacent functionally localized areas in extrastriate cortex. In three experiments, participants performed discrimination tasks involving faces, bodies, and objects while TMS was delivered over the right occipital face area (rOFA) , the right extrastriate body area (rEBA) , or the right lateral occipital area (rLO) . All three experiments showed a task selective dissociation with performance impaired only by stimulation at the site selective for that category: TMS over rOFA impaired discrimination of faces but not objects or bodies; TMS over rEBA impaired discrimination of bodies but not faces or objects; TMS over rLO impaired discrimination of objects but not faces or bodies. The results support a modular account in which category-selective areas contribute solely to discrimination of their preferred categories. PMID:19200723
Pitcher, David; Charles, Lucie; Devlin, Joseph T; Walsh, Vincent; Duchaine, Bradley
The effect of multi-modal vs uni-modal prior stimuli on the subsequent processing of a simple flash stimulus was studied in the context of the audio-visual ‘flash-beep’ illusion, in which the number of flashes a person sees is influenced by accompanying beep stimuli. EEG recordings were made while combinations of simple visual and audio-visual stimuli were presented. The experiments found that the electric field strength related to a flash stimulus was stronger when it was preceded by a multi-modal flash/beep stimulus, compared to when it was preceded by another uni-modal flash stimulus. This difference was found to be significant in two distinct timeframes – an early timeframe, from 130–160 ms, and a late timeframe, from 300–320 ms. Source localisation analysis found that the increased activity in the early interval was localised to an area centred on the inferior and superior parietal lobes, whereas the later increase was associated with stronger activity in an area centred on primary and secondary visual cortex, in the occipital lobe. The results suggest that processing of a visual stimulus can be affected by the presence of an immediately prior multisensory event. Relatively long-lasting interactions generated by the initial auditory and visual stimuli altered the processing of a subsequent visual stimulus.
Innes-Brown, Hamish; Barutchu, Ayla; Crewther, David P.
Quantitative descriptions of the occipital sinus are lacking in the extant medical literature. Posterior fossa duras with the superior sagittal sinus, the inferior and superior petrosal sinuses were dissected and taken out from fresh human cadavers by cutting at the superior sagittal sinus, the marginal sinuses and the petrosal sinuses bilaterally. The length of the occipital sinuses was measured using calipers. A 0.5-cm section of the occipital sinus was cut out at its midpoint and prepared for measurements of the perimeter and diameter using a stereology workstation. The sinuses were also examined qualitatively using a surgical microscope. There was no occipital sinus in 6.6% of total 30 cases. Multiple occipital sinuses were seen in 10%. In one specimen, the sinus seemed incomplete, failing to reach the marginal sinuses. Some specimens gave the impression that more than one occipital sinus was present, nevertheless, careful dissection showed connections. The breadth of the sinus steadily narrowed downward in direction of foramen magnum. The inner wall with many fibrous bridges was tight, except the lateral parts that were easily separated into two dural sheets. The length of the sinus varied from 10 to 37 mm. The inner diameter (feret maximum) varied from 0.33 to 7.06 mm at midpoint. The breadth of the multiple sinuses did not exceed the mean of our series except in one case. The occipital sinus, which is generally ellipsoid in shape, functions in the majority of cases as a thin, single midline sinus. It may have less resistant recesses laterally. PMID:20196130
Balak, Naci; Ersoy, Gökhan; Uslu, Unal; Tanriöver, Necmettin; Tapul, Leyla; Cetin, Gürsel; I?ik, Nejat; Elmaci, Ilhan
The analysis of ossification points plays a considerable role in forensic age estimation. Although traditional methods are still in use, researchers are working on different age estimation procedures especially within the development of radiologic methods. One of these methods is to define spheno-occipital synchondrosis fusion degree. Spheno-occipital synchondrosis, an important growth point on cranial base, provides noteworthy information about age estimation through its late stage ossification nature. This study aimed to investigate spheno-occipital synchondrosis fusion degree for age estimation in the Turkish population. In our study, 1-mm-sectioned computed tomography images of 638 (399 men and 139 women) subjects within the age of 10 to 25 years were retrospectively examined. It is stated in our study that spheno-occipital syncondrosis fusion begins superiorly and progresses inferiorly until it is completed. Spheno-occipital syncondrosis is known to be totally open at the mean (SD) age of 11.5 (1.5) years in men and 10.7 (0.8) years in women. In addition, fusion degree is known to be increased with age. Fusion starts approximately 2 years earlier in women than in men, and the process of fusion completes at the age of 17 years in both sexes. An analysis of fusion degree between sex groups showed significance at the age of 11 to 15 years, and Spearman rank correlations indicate a significant positive relationship between age and degree of spheno-occipital fusion (P < 0.001; men, ? = 0.714; women, ? = 0.698). Consequently, 5-staged analysis of spheno-occipital synchondrosis fusion degree in use with 1-mm computed tomography images will be helpful for age estimation between 11 and 17 years. PMID:25006899
Can, Ismail Ozgur; Ekizoglu, Oguzhan; Hocaoglu, Elif; Inci, Ercan; Sayin, Ibrahim; Kaya, Kamil Hakan
Over the past 30 years researchers have learned a great deal about the development of object processing in infancy. In contrast, little is understood about the neural mechanisms that underlie this capacity, in large part because there are few techniques available to measure brain functioning in human infants. The present research examined the…
Wilcox, Teresa; Bortfeld, Heather; Woods, Rebecca; Wruck, Eric; Boas, David A.
In humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single-unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal
Patrizia Fattori; Rossella Breveglieri; Katia Amoroso; Claudio Galletti
A recent study in humans (McDonald et al., 2013) found that peripheral, task-irrelevant sounds activated contralateral visual cortex automatically as revealed by an auditory-evoked contralateral occipital positivity (ACOP) recorded from the scalp. The present study investigated the functional significance of this cross-modal activation of visual cortex, in particular whether the sound-evoked ACOP is predictive of improved perceptual processing of a subsequent visual target. A trial-by-trial analysis showed that the ACOP amplitude was markedly larger preceding correct than incorrect pattern discriminations of visual targets that were colocalized with the preceding sound. Dipole modeling of the scalp topography of the ACOP localized its neural generators to the ventrolateral extrastriate visual cortex. These results provide direct evidence that the cross-modal activation of contralateral visual cortex by a spatially nonpredictive but salient sound facilitates the discriminative processing of a subsequent visual target event at the location of the sound. Recordings of event-related potentials to the targets support the hypothesis that the ACOP is a neural consequence of the automatic orienting of visual attention to the location of the sound. PMID:25031419
Feng, Wenfeng; Störmer, Viola S; Martinez, Antigona; McDonald, John J; Hillyard, Steven A
OBJECTIVESTo make a personal report of a hemianopia due to an occipital infarct, sustained by a professor of neurology.METHODSVerbatim observation of neurological phenomena recorded during the acute illness.RESULTSHemianopia, visual hallucinations, and non-occipital deficits without extraoccipital lesions on MRI, are described and discussed.CONCLUSIONSHemianopia, due to an occipital infarct, without alexia, is not a disability which precludes a normal professional career. Neurorehabilitation
Two patients with occipital neuralgia due to severe arthropathy of the C1-2 facet joint were treated using atlantoaxial fusion with transarticular screws without decompression of the C-2 nerve root. Both patients experienced immediate postoperative relief of occipital neuralgia. The resultant motion elimination at C1-2 eradicated not only the movement-evoked pain, but also the paroxysms of true occipital neuralgia occurring at rest. A possible pathophysiological explanation for this improvement is presented in the context of the ignition theory of neuralgic pain. This represents the first report of C1-2 transarticular screw fixation for the treatment of arthropathy-associated occipital neuralgia. PMID:21214317
Human attention may be guided by representations held in working memory (WM) and also by priming from implicit memory. Neurophysiological data suggest that WM and priming may be associated with distinct neural mechanisms, but this prior evidence is only correlative. Furthermore, the role of the visual cortex in attention biases from memory remains unclear, because most previous studies conflated memory and selection processes. Here, we manipulated memory and attention in an orthogonal fashion and used an interventional approach to demonstrate the functional significance of WM and priming states in visual cortex for attentional biasing. Observers searched for a Landolt target that was preceded by a nonpredictive color cue that either had to be held in WM for a later recognition test or merely attended (priming counterpart). The application of transcranial magnetic stimulation (TMS) over the occipital cortex modulated the impact of memory on search. Critically, the direction of this modulation depended on the memory state. In the WM condition, the application of TMS on validly cued trials (when the cue surrounded the sought target) enhanced search accuracy relative to the invalid trials (when the cue surrounded a distracter); the opposite pattern was observed in the priming condition. That the effects of occipital TMS on selection were contingent on memory context demonstrates that WM and priming represent distinct states in the early visual cortex that play a causal role in memory-based guidance of attention. PMID:22399767
Soto, David; Llewelyn, Dafydd; Silvanto, Juha
Phosphene sensation is commonly used to measure cortical excitability during transcranial magnetic stimulation (TMS) of the occipital cortex. However, some individuals lack this perception, and the reason for it is still unknown. In this work, we used functional magnetic resonance imaging (fMRI) to detect brain activation during local TMS of the occipital cortex in twelve healthy subjects. We found that TMS modulated brain activity in areas connected to the stimulation site, even in people unable to see phosphene. However, we observed a trend for a lower blood-oxygenation-level dependent (BOLD) signal, and smaller brain-activation clusters near the stimulated site than in the interconnected brain areas, suggesting that TMS pulse is more effective downstream than at its application site. Furthermore, we noted prominent differences in brain activation/deactivation patterns between subjects who perceived phosphene and those who did not, implying a functional distinction in their neuronal networks that might explain the origin of differences in phosphene generation.
Caparelli, E.C.; Backus, W.; Telang, F.; Wang, G-J; Maloney, T.; Goldstein, R.Z.; Anschel, D.; Henn, F.
Introduction: Encephalocele, midline defect of cranial bone fusion, occurs most frequently in the occipital region. Airway management in pediatric patients with craniofacial disorders poses many challenges to the anesthesiologist. The purpose of this study is to describe the airway problems encountered for such cases, and describe how these problems were managed. Materials and Methods: We reviewed the charts of occipital encephalocele newborn that were treated by surgical correction in Harran University Hospital during 2006–2008. The collected data were categorized into preoperative, intraoperative, and postoperative data. Results: The mean age of the patients was 5.17 days. Of these 17 patients, eight patients (47.1%) had hydrocephaly, one patient (5.8%) with Dandy Walker syndrome. Micrognathia, macroglossia, restriction in neck movements were recorded as the reasons in six cases each. No major anesthetic complication was found. Conclusions: We reported perioperative management in 17 occipital encephalocele infant. Comprehensive care during peroperative period is essential for successful outcome.
Y?ld?r?m, Zeynep Baysel; Avci, Emel; Torun, Fuat; Cengiz, Mustafa; Cigdem, Ali; Karabag, Hamza; Karaman, Haktan
Introduction Occipital artery aneurysms are very rare vascular lesions. Most cases reported in the literature have been post-traumatic pseudoaneurysms of the occipital artery. Case presentation We report the case of a 14-year-old Caucasian boy presented with a painless non-pulsatile scalp mass that developed rapidly after minor blunt head trauma. The scalp mass was excised six months after the trauma. A pathologic diagnosis of a thrombosed true aneurysm was made. Our patient has had no recurrence of the mass at 15?months follow-up. Conclusions We present a case of a true aneurysm of the occipital artery following minor head trauma. We review the literature for similar cases and discuss the difficulty of establishing a diagnosis prior to surgical intervention.
Oculomotor events such as blinks and saccades transiently interrupt the visual input and, even though this mostly goes undetected, these brief interruptions could still influence the percept. In particular, both blinking and saccades facilitate switching in ambiguous figures such as the Necker cube. To investigate the neural state antecedent to these oculomotor events during the perception of an ambiguous figure, we measured the human scalp electroencephalogram (EEG). When blinking led to perceptual switching, antecedent occipital alpha band activity exhibited a transient increase in amplitude. When a saccade led to switching, a series of transient increases and decreases in amplitude was observed in the antecedent occipital alpha band activity. Our results suggest that the state of occipital alpha band activity predicts the impact of oculomotor events on the percept.
Nakatani, Hironori; van Leeuwen, Cees
In this work the design and fabrication of a novel passive microfluidic mixer capable of achieving mixing in shorter distances and lower Reynolds numbers (Re) is reported. Passive mixers typically rely on the channel geometry to mix fluids, and many previously reported designs work efficiently only at moderate to high Re and are often difficult to fabricate as they incorporate complex 3-D structures within the channel. The mixer design discussed in this work achieves good mixing at low Re, has planar geometry and thus is simpler to fabricate and integrate with existing labon- a-chip (LOC) technologies. The design incorporates triangular notches patterned along the channel walls to laminate the flow, thus enhancing mixing. Numerical and experimental studies to determine the effect of the notch dimensions and placement within the microchannel were carried out to optimize the mixing performance. Results show that the final mixer design is efficient at mixing fluids at low Re. The mixer is fabricated in polydimethylsiloxane (PDMS) bonded to glass slides and tested using fluorescence dyes. Results show that the new design exhibit complete mixing at Re < 0.1 within 7 mm and thus will benefit a wide range of LOC applications where space is limited.
Bhagat, Ali Asgar S.; Peterson, Erik T. K.; Papautsky, Ian
INTRODUCTION. Occipital neuralgia is a pain in the distribution of the occipital nerves, accompanied by hypersensitivity to touch in the corresponding territory. AIMS. We present the occipital neuralgia series from the specialised headache unit at a tertiary hospital and analyse its clinical characteristics and its response to therapy. PATIENTS AND METHODS. Variables were collected from the cases of occipital neuralgia diagnosed in the above-mentioned headache unit between January 2008 and April 2013. RESULTS. A series of 14 patients (10 females, 4 males) with occipital neuralgia was obtained out of a total of 2338 (0.59%). Age at onset of the clinical signs and symptoms: 53.4 ± 20.3 years (range: 17-81 years) and time elapsed to diagnosis was 35.5 ± 58.8 months (range: 1-230 months). An intracranial or cervical pathology was ruled out by suitable means in each case. Baseline pain of a generally oppressive nature and an intensity of 5.3 ± 1.3 (4-8) on the verbal analogue scale was observed in 13 of them (92.8%). Eleven (78.5%) presented exacerbations, generally stabbing pains, a variable frequency (4.6 ± 7 a day) and an intensity of 7.8 ± 1.7 (range: 4-10) on the verbal analogue scale. Anaesthetic blockade was not performed in four of them (two due to a remitting pattern and two following the patient's wishes); in the others, blockade was carried out and was completely effective for between two and seven months. Four cases had previously received preventive treatment (amitriptyline in three and gabapentin in one), with no response. CONCLUSIONS. In this series from a specialised headache unit, occipital neuralgia is an infrequent condition that mainly affects patients over 50 years of age. Given its poor response to preventive treatment, the full prolonged response to anaesthetic blockades must be taken into account. PMID:23975524
Pedraza, María Isabel; Ruiz, Marina; Rodríguez, Cristina; Muñoz, Irene; Barón, Johanna; Mulero, Patricia; Herrero-Velázquez, Sonia; Guerrero-Peral, Ángel L
Mammalian odorant receptors have been known to be involved not only in odorant detection but also in neuronal development of olfactory sensory neurons. We have examined a possibility of odorant receptor expression in nonolfactory neurons in the mouse. Mouse odorant receptors (M71, C6, and OR3), two of which were already shown to be functionally activated by odorants in heterologous systems, were detected by polymerase chain reactions (PCRs) from the cerebral cortex but not from other brain tissues. Degenerate PCR further suggested that other odorant receptors were also expressed in the mouse cerebral cortex. One of these receptors showed high sequence-match with a putative chick odorant receptor OR7 transiently expressed in the notochord during development. In situ hybridization detected signals for M71 and C6 receptors in the layer II cortical pyramidal neurons located in the occipital pole. In the M71-IRES-tauLacZ mouse, in which M71 expression was genetically marked with tauLacZ, X-gal staining signals were mostly localized in the layer II neurons in the occipital pole, being consistent with the in situ hybridization result. Fluorescent immunohistochemistry using anti-beta-galactosidase antibody further detected the tauLacZ signals in the same cells. X-gal staining began at P3, peaked at P8, and continued to adults, although signals gradually decreased. These data showed that at least a few odorant receptors are expressed not only in olfactory sensory neurons but also in pyramidal neurons in the cerebral cortex, possibly playing an important role either in chemical detection of exogenous or endogenous ligands or in a developmental process such as axon guidance and target recognition. PMID:14750145
Otaki, Joji M; Yamamoto, Haruhiko; Firestein, Stuart
Headache occipital neuralgia is an example of pain-disease for which treatment both pharmacological protocols and invasive methods are used. Among the latter, the RF (Radiofrequency) pulse-dose has been of interest for the prospects of analgesic efficacy, safety and patient compliance, although at the moment only data concerning the pulsed RF and not the RF pulse-dose, that represents its evolution, are discussed in scientific literature. The purpose of this study is a “simple” economic evaluation of this method in headache occipital neuralgia.
Giovannini, Vittoria; Pusateri, Rachele; Russo, Viera; Viscardi, Daniela; Palomba, Rosa
Headache occipital neuralgia is an example of pain-disease for which treatment both pharmacological protocols and invasive methods are used. Among the latter, the RF (Radiofrequency) pulse-dose has been of interest for the prospects of analgesic efficacy, safety and patient compliance, although at the moment only data concerning the pulsed RF and not the RF pulse-dose, that represents its evolution, are discussed in scientific literature. The purpose of this study is a "simple" economic evaluation of this method in headache occipital neuralgia. PMID:23905049
Giovannini, Vittoria; Pusateri, Rachele; Russo, Viera; Viscardi, Daniela; Palomba, Rosa
A 28-year-old man developed cerebral blindness from infarction of both mesial occipital lobes after cardiogenic hypotension induced by electrical shock. He remained globally encephalopathic for several weeks, but his most enduring deficit was bilateral homonymous hemianopias with macular sparing. Cerebral visual loss after electrical injury has been sparsely reported. It has been attributed to direct thermal injury of the skull or posterior dural venous sinuses. We suggest that cerebral blindness after cardiogenic hypotension in which there is no thermal injury to the scalp be attributed to hypotensive infarction of the mesial occipital lobes, which lie in the terminal domain of the posterior cerebral arteries. PMID:19491633
Kamyar, Roheena; Trobe, Jonathan D
Human visual cortex contains maps of the visual field. Much research has been dedicated to answering whether and when these visual field maps change if critical components of the visual circuitry are damaged. Here, we first provide a focused mini-review of the functional magnetic resonance imaging (fMRI) studies that have evaluated the human cortical visual field maps in the face of retinal lesions, brain injury, and atypical retinocortical projections. We find that there is a fair body of research that has found abnormal fMRI activity, but also that this abnormal activity does not necessarily stem from cortical remapping. The abnormal fMRI activity can often be explained in terms of task effects and/or the uncovering of normally hidden system dynamics. We then present the case of a 16-year-old patient who lost the entire left cerebral hemisphere at age three for treatment of chronic focal encephalitis (Rasmussen syndrome) and intractable epilepsy. Using an fMRI retinotopic mapping procedure and population receptive field (pRF) modeling, we found that (1) despite the long period since the hemispherectomy, the retinotopic organization of early visual cortex remained unaffected by the removal of an entire cerebral hemisphere, and (2) the intact lateral occipital cortex contained an exceptionally large representation of the center of the visual field. The same method also indicates that the neuronal receptive fields in these lateral occipital brain regions are extraordinarily small. These features are clearly abnormal, but again they do not necessarily stem from cortical remapping. For example, the abnormal features can also be explained by the notion that the hemispherectomy took place during a critical period in the development of the lateral occipital cortex and therefore arrested its normal development. Thus, caution should be exercised when interpreting abnormal fMRI activity as a marker of cortical remapping; there are often other explanations. PMID:23347557
Haak, Koen V; Langers, Dave R M; Renken, Remco; van Dijk, Pim; Borgstein, Johannes; Cornelissen, Frans W
Schizophrenia is a complex brain disorder associated with numerous etiological factors and pathophysiological pathways leading to multiple clinical outcomes. Compelling evidence suggests that deviations in neurodevelopmental processes are a major risk factor of schizophrenia. The identification of patients with high neurodevelopmental deviance is an important issue as it could help to identify homogeneous subgroups of patients with similar pathophysiological pathways, a key step to decipher the etiology of this complex condition. Several clinical arguments suggest that schizophrenia patients with Neurological Soft Signs (NSS)--ie, observable defects in motor coordination, motor integration, and sensory integration--would have high neurodevelopmental deviance. Based on the analysis of magnetic resonance imaging of 44 first-episode psychosis patients, we compared the cortex morphology, a marker of brain development, in patients with NSS vs patients with nonsignificant NSS. The cortex morphology was automatically assessed from three-dimensional global sulcal index (g-SI, the ratio between total sulcal area and outer cortex area) and regional sulcal indexes (r-SI, the ratio between the area of pooled labeled sulci and the total outer cortex area). Patients with NSS were found to have a lower g-SI in both hemispheres and a lower r-SI in left dorsolateral prefrontal and right lateral occipital cortices. Exploratory analyses revealed correlations between NSS dimensions and r-SI in distinct cortical areas, including dorsolateral and medial prefrontal cortices, lateral temporal, occipital, superior parietal, and medial parieto-occipital cortices. These findings provide evidence of distinct neurodevelopmental pathways in patients with NSS as compared with patients with nonsignificant NSS. PMID:22892556
Gay, Olivier; Plaze, Marion; Oppenheim, Catherine; Mouchet-Mages, Sabine; Gaillard, Raphaël; Olié, Jean-Pierre; Krebs, Marie-Odile; Cachia, Arnaud
SUMMARY While there are selective regions of occipito-temporal cortex that respond to faces, letters, and bodies, the large-scale neural organization of most object categories remains unknown. Here we find that object representations can be differentiated along the ventral temporal cortex by their real-world size. In a functional neuroimaging experiment, observers were shown pictures of big and small real-world objects (e.g. table, bathtub; paperclip, cup), presented at the same retinal size. We observed a consistent medial-to-lateral organization of big and small object preferences in the ventral temporal cortex, mirrored along the lateral surface. Regions in the lateral-occipital, infero-temporal, and parahippocampal cortices showed strong peaks of differential real-world size selectivity, and maintained these preferences over changes in retinal size and in mental imagery. These data demonstrate that the real-world size of objects can provide insight into the spatial topography of object representation.
Konkle, Talia; Oliva, Aude
In this contribution, the great potential of surface enhanced Raman spectroscopy (SERS) in a lab-on-a-chip (LOC) device for the detection of analyte molecules in a complex environment is demonstrated. Using LOC-SERS, the enzyme activity of thiopurine S-methyltransferase (TPMT) is analysed and identified in lysed red blood cells. The conversion of 6-mercaptopurine to 6-methylmercaptopurine catalysed by TPMT is observed as it gives evidence for the enzyme activity. Being able to determine the TPMT activity before starting a treatment using 6-mercaptopurine, an optimized dosage can be applied to each patient and serious toxicity appearing within thiopurine treatment will be prevented. PMID:21359568
März, Anne; Mönch, Bettina; Rösch, Petra; Kiehntopf, Michael; Henkel, Thomas; Popp, Jürgen
The Pax-1 gene has been found to play an important role in the development of the vertebral column. The cervico-occipital transitional zone is a specialized region of the vertebral column, and malformations of this region have frequently been described in humans. The exact embryonic border between head and trunk is a matter of controversy. In order to determine a possible
Jörg Wilting; Cecilia Ebensperger; Thomas S. Müller; Haruhiko Koseki; Johan Wallin; Bodo Christ
Three retarded epileptic individuals (17 to 22 years old) with a variety of seizure disorders were provided with 8 to 12 Hz occipital EEG biofeedback training. While seizures were not totally eliminated in any of the Ss, the results of the study indicated that all Ss exhibited decreases in some aspect of their seizure activity. (Author)
Rudrud, Eric; Striefel, Sebastian
This is a qualitative and chronological analysis of ictal and postictal symptoms, frequency of seizures, family history, response to treatment, and prognosis in nine patients with idiopathic occipital epilepsy and visual seizures. Ictal elementary visual hallucinations are stereotyped for each patient, usually lasting for seconds. They consist of mainly multiple, bright coloured, small circular spots, circles, or balls. Mostly, they
C P Panayiotopoulos
The extent to which primary visual cues such as motion or luminance are segregated in different cortical areas is a subject of controversy. To address this issue, we examined cortical activation in the human occipital lobe using functional magnetic resonance imaging (fMRI) while subjects performed a fixed visual task, object recognition, using three different primary visual cues: motion, texture, or
Kalanit Grill-Spector; Tamar Kushnir; Shimon Edelman; Yacov Itzchak; Rafael Malach
The development of pressure ulcers in acute care settings remains an important concern, especially in high-risk populations such as patients who are critically ill and admitted to an ICU setting. In addition to immobility and other risk factors associated with critical illness, occipital pressure ulcer development has been associated with young age (neonates, infants, and young children) and patient care devices (cervical collars, bed lateral rotation). A 7-year-old boy was admitted to the pediatric intensive care unit with severe sepsis that progressed to multi-organ failure including respiratory distress requiring mechanical ventilation, cardiovascular failure requiring extracorporeal membrane oxygenation, and renal failure requiring dialysis. At 4 weeks, hair braids that were placed before admission were taken down, revealing five full-thickness occipital lesions. All wounds eventually healed, but scarring alopecia at the site of the largest wound was visible. This is the first case study describing hair braids as a potential risk factor for occipital pressure-related skin dam- age and suggests that if a patient is immobile and admitted with braids, patient/family and nursing staff education should include discussing the importance of releasing the hair to decrease the risk of occipital ulcers. PMID:21918247
Dixon, Marilu; Ratliff, Catherine
Aim. Panayiotopoulos syndrome (PS) is an age-related seizure susceptibility syndrome that affects the central autonomic system. Although the majority of the few ictal recordings obtained so far suggest an occipital origin, semiological and interictal EEG data appear to favour more extensive involvement. In this study, the characteristics (including those based on semiology and EEG) of children with Panayiotopoulos syndrome (n=24) and those with lesion-related, symptomatic occipital lobe epilepsy (SOLE) (n=23) were compared. Methods. Detailed semiological information and EEG parameters including the localisation, distribution, density (n/sec), reactivity, and morphological characteristics of spike-wave foci and their relationship with different states of vigilance were compared between the two groups. Results. The age at seizure onset was significantly younger in patients with symptomatic occipital lobe epilepsy than in those with PS (mean age at onset: 3.4 versus 5.6 years, respectively; p=0.044). Autonomic seizures (p=0.001) and ictal syncope (p=0.055) were more frequent in PS than in symptomatic occipital lobe epilepsy (87.5% and 37.5% versus 43.5% and 13%, respectively). The interictal spike-wave activity increased significantly during non-rapid eye movement (non-REM) sleep in both groups. The spike waves in non-REM seen in PS tended to spread mainly to central and centro-temporal regions. Conclusions. The results indicate that although common features do exist, Panayiotopoulos syndrome differs from symptomatic occipital lobe epilepsy and has a unique low epileptogenic threshold related to particular brain circuits. PMID:24777033
Tata, Gulten; Guveli, Betul Tekin; Dortcan, Nimet; Cokar, Ozlem; Kurucu, Hatice; Demirbilek, Veysi; Dervent, Aysin
Interictal or ictal events in partial epilepsies may project on scalp EEG contralaterally to the side of the epileptogenic lesion. Such paradoxical lateralization can be observed in case of para-sagittal generators, and is likely due to the spatial orientation of the generator, presenting an oblique projection towards the midline. We present here a case of medial occipital epilepsy investigated using EEG, MEG and stereoelectroencephalography (SEEG). MRI displayed a focal cortical dysplasia in the superior margin of the right calcarine fissure. SEEG demonstrated bilateral medial occipital interictal spikes, with an inversion of polarity at the level of the lesion and a contralateral propagation occurring in 10 ms. Interictal iterative EEG cartographies showed a large posterior field, with a maximum contralateral to the initial generator (EEG paradoxical lateralization). With the same number of channels, interictal iterative MEG cartographies were more precise and more complex than EEG ones, indicating an onset accurately lateralized. A few milliseconds later, MEG cartographies were quadripolar, thus indicating two homotopic active generators. These MEG and EEG cartographies have been reproduced using BESA dipole simulator. Relative merits of MEG and EEG are still debated. With 151 channels, MEG source localizations indicated the right medial occipital area, as demonstrated by SEEG. An investigation with a corresponding number of EEG channels was not performed. After a down sampling to 64 sensors, this precision was lost. MEG and EEG source localization results, both with 64 channels, were quite comparable, indicating both medial occipital areas. However, a careful analysis of MEG/EEG iterative cartographies, performed with the same number of channels in both modalities, demonstrated that, in this configuration, MEG sensitivity was superior to the EEG one, allowing separating two medial occipital sources, characterized in SEEG by a time delay of 10 ms. PMID:24005334
Gavaret, Martine; Badier, Jean-Michel; Bartolomei, Fabrice; Bénar, Christian-Georges; Chauvel, Patrick
We have used positron emission tomography (PET), which measures regional cerebral blood flow (rCBF), to demonstrate directly the specialization of function in the normal human visual cortex. A novel technique, statistical parametric mapping, was used to detect foci of significant change in cerebral blood flow within the prestriate cortex, in order to localize those parts involved in the perception of color and visual motion. For color, we stimulated the subjects with a multicolored abstract display containing no recognizable objects (Land color Mondrian) and contrasted the resulting blood flow maps with those obtained when subjects viewed an identical display consisting of equiluminous shades of gray. The comparison identified a unique area (area V4) located in the lingual and fusiform gyri of the prestriate cortex. For motion, blood flow maps when subjects viewed moving or stationary black and white random-square patterns were contrasted. The comparison identified a unique area located in the region of the temporo-parieto-occipital junction (area V5). We thus provide direct evidence to show that, just as in the macaque monkey, different areas of the human prestriate visual cortex are specialized for different attributes of vision. The striate cortex (V1) and the contiguous visual area (V2), which in the monkey brain feed both the homologous areas, were active in all 4 conditions. This pattern of activity allowed us to use an extension of the approach to assess the functional relationship between the 3 areas during color and motion stimulation. This is based on an hypothesis-led analysis of the covariance structure of the blood flow maps and promises to be a powerful tool for inferring anatomical pathways in the normal human brain.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2002358
Zeki, S; Watson, J D; Lueck, C J; Friston, K J; Kennard, C; Frackowiak, R S
Parkinson's disease (PD) is a complex neurodegenerative condition involving a motor disorder that is related to reduced dopaminergic input to the striatum. Intellectual deficits are also seen in PD, but the pathophysiology of these difficulties is poorly understood. Regional cerebral blood flow (rCBF) was studied in neurologically intact subjects during the performance of attention-demanding, sentence processing tasks using positron emission tomography (PET). The results demonstrated significantly increased rCBF in a distributed set of cerebral regions during the detection of an adjective or a particular agent in a sentence, including anterior cingulate cortex, left inferior and middle frontal cortex, left inferior temporo-occipital cortex, posterolateral temporal cortex, left caudate, and left thalamus. We identified defects in this cerebral network by studying PD patients with two PET techniques. Resting PET studies revealed a significant correlation between regional cerebral glucose metabolism in anterior cingulate cortex and deficits in attending to subtle grammatical aspects of sentences. Studies of PD patients with the PET activation technique revealed little change in anterior cingulate and left frontal CBF during performance of the adjective detection or agent detection tasks. These data suggest that a defect in anterior cingulate cortex contributes to the cognitive impairments observed in PD. PMID:1477527
Grossman, M; Crino, P; Reivich, M; Stern, M B; Hurtig, H I
Unlike natural numbers, negative numbers do not have natural physical referents. How does the brain represent such abstract mathematical concepts? Two competing hypotheses regarding representational systems for negative numbers are a rule-based model, in which symbolic rules are applied to negative numbers to translate them into positive numbers when assessing magnitudes, and an expanded magnitude model, in which negative numbers have a distinct magnitude representation. Using an event-related functional magnetic resonance imaging design, we examined brain responses in 22 adults while they performed magnitude comparisons of negative and positive numbers that were quantitatively near (difference <4) or far apart (difference >6). Reaction times (RTs) for negative numbers were slower than positive numbers, and both showed a distance effect whereby near pairs took longer to compare. A network of parietal, frontal, and occipital regions were differentially engaged by negative numbers. Specifically, compared to positive numbers, negative number processing resulted in greater activation bilaterally in intraparietal sulcus (IPS), middle frontal gyrus, and inferior lateral occipital cortex. Representational similarity analysis revealed that neural responses in the IPS were more differentiated among positive numbers than among negative numbers, and greater differentiation among negative numbers was associated with faster RTs. Our findings indicate that despite negative numbers engaging the IPS more strongly, the underlying neural representation are less distinct than that of positive numbers. We discuss our findings in the context of the two theoretical models of negative number processing and demonstrate how multivariate approaches can provide novel insights into abstract number representation.
Blair, Kristen P.; Rosenberg-Lee, Miriam; Tsang, Jessica M.; Schwartz, Daniel L.; Menon, Vinod
Three cortical areas (Retro-Splenial Cortex (RSC), Transverse Occipital Sulcus (TOS) and Parahippocampal Place Area (PPA)) respond selectively to scenes. However, their wider role in spatial encoding and their functional connectivity remain unclear. Using fMRI, first we tested the responses of these areas during spatial comparison tasks using dot targets on white noise. Activity increased during task performance in both RSC and TOS, but not in PPA. However, the amplitude of task-driven activity and behavioral measures of task demand were correlated only in RSC. A control experiment showed that none of these areas were activated during a comparable shape comparison task. Secondly, we analyzed functional connectivity of these areas during the resting state. Results revealed a significant connection between RSC and frontal association areas (known to be involved in perceptual decision-making). In contrast, TOS showed functional connections dorsally with the Inferior Parietal Sulcus, and ventrally with the Lateral Occipital Complex--but not with RSC and/or frontal association areas. Moreover, RSC and TOS showed differentiable functional connections with the anterior-medial and posterior-lateral parts of PPA, respectively. These results suggest two parallel pathways for spatial encoding, including RSC and TOS respectively. Only the RSC network was involved in active spatial comparisons. PMID:23872156
Nasr, Shahin; Devaney, Kathryn J; Tootell, Roger B H
Aim: The objective of this in vivo dissolution study was to investigate the usefulness of the Loc-I-Gut® technique for differentiating between the in vivo dissolution rate of two particle sizes of spironolactone, and to compare these in vivo results with corresponding in vitro data. Methods: The study included six volunteers, and consisted of three sequential parts (I, II, III). In
Lisbet Bønløkke; Lars Hovgaard; Henning G. Kristensen; Lars Knutson; Hans Lennernäs
A bio-microfluidic package has been developed with integrated reservoir and valves for DNA (deoxyribonucleic acid) lab on a chip (LOC) application. A polymer material, PDMS (polydimethylsiloxane) is used for encapsulating the DNA chip. Channels, reservoirs and valves are formed on the PDMS material by casting method. A double sided adhesive tape is used to bond PDMS substrates and DNA chip.
Ling Xie; C. S. Premachandran; Ser Choong Chong; Michelle Chew
Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction. Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early–onset strabismic subject with binocular suppression, indicating real-time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.
Conner, Ian P; Odom, J Vernon; Schwartz, Terry L; Mendola, Janine D
Functional neuroimaging studies have consistently reported abnormalities in the visual cortex in patients with dementia with Lewy bodies (DLB), but their neuropathologic substrates are poorly understood. We analyzed synaptic proteins and choline acetyltransferase (ChAT) in the primary (BA17) and association (BAs18/19) visual cortex in DLB and similar aged control and Alzheimer disease (AD) subjects. We found lower levels of synaptophysin, syntaxin, SNAP-25, and ?-synuclein in DLB subjects versus both aged control (68%-78% and 27%-72% for BA17 and BAs18/19, respectively) and AD cases (54%-67% and 10%-56% for BA17 and BAs18/19, respectively). The loss in ChAT activity in DLB cases was also greater in BA17 (72% and 87% vs AD and control values, respectively) than in BAs18/19 (52% and 65% vs AD and control groups, respectively). The observed synaptic and ChAT changes in the visual cortices were not associated with tau or ?-amyloid pathology in the occipital or the frontal, temporal, and parietal neocortex. However, the neocortical densities of LBs, particular those in BA17 and BAs18/19, correlated with lower synaptic and ChAT levels in these brain areas. These findings draw attention to molecular changes within the primary visual cortex in DLB and correlate with the neuroimaging findings within the occipital lobe in patients with this disorder. PMID:23242284
Mukaetova-Ladinska, Elizabeta B; Andras, Alina; Milne, Joan; Abdel-All, Zeinab; Borr, Iwo; Jaros, Evelyn; Perry, Robert H; Honer, William G; Cleghorn, Andrea; Doherty, Jeanette; McIntosh, Gary; Perry, Elaine K; Kalaria, Raj N; McKeith, Ian G
Cranial sutures and synchondrosis have long been studied by forensic scientists, human anatomists, and anthropologists for estimation of age in different population groups. Observation of the closure of spheno-occipital synchondrosis has an important role to play in the estimation of age in the examination of unknown human remains when a skull is brought for examination. The present article reviews the studies conducted on the closure of spheno-occipital synchondrosis and presents a few valuable considerations that would be essential for carrying out research related to closure of spheno-occipital synchondrosis in humans.
Krishan, Kewal; Kanchan, Tanuj
Study Objective: This study aims at providing a quantitative description of intrinsic spindle frequency and density (number of spindles/min) in cortical areas using deep intracerebral recordings in humans. Patients or Participants: Thirteen patients suffering from pharmaco-resistant focal epilepsy and investigated through deep intracortical EEG in frontal, parietal, temporal, occipital, insular, and limbic cortices including the hippocampus were included. Methods: Spindle waves were detected from the ongoing EEG during slow wave sleep (SWS) by performing a time-frequency analysis on filtered signals (band-pass filter: 10-16 Hz). Then, spindle intrinsic frequency was determined using a fast Fourier transform, and spindle density (number of spindles per minute) was computed. Results: Firstly, we showed that sleep spindles were recorded in all explored cortical areas, except temporal neocortex. In particular, we observed the presence of spindles during SWS in areas such as the insular cortex, medial parietal cortex, occipital cortex, and cingulate gyrus. Secondly, we demonstrated that both spindle frequency and density smoothly change along the caudo-rostral axis, from fast frequent posterior spindles to slower and less frequent anterior spindles. Thirdly, we identified the presence of spindle frequency oscillations in the hippocampus and the entorhinal cortex. Conclusions: Spindling activity is widespread among cortical areas, which argues for the fundamental role of spindles in cortical functions. Mechanisms of caudo-rostral gradient modulation in spindle frequency and density may result from a complex interplay of intrinsic properties and extrinsic modulation of thalamocortical and corticothalamic neurons. Citation: Peter-Derex L; Comte JC; Mauguière F; Salin PA. Density and frequency caudo-rostral gradients of sleep spindles recorded in the human cortex. SLEEP 2012;35(1):69-79.
Peter-Derex, Laure; Comte, Jean-Christophe; Mauguiere, Francois; Salin, Paul A.
Giant cell tumors (GCTs) are usually found in the epiphysis of the long bones, and represent ~5% of all bone tumors. Only <1% of GCTs are localized in the cranium. When localized in the cranium, GCTs are commonly observed in the sphenoid or temporal bones, and rarely in the parietal or frontal bones. Occipital bone posterior fossa involvement is an extremely rare occurrence. The current study presents a 22-year-old female patient was admitted to the Department of Radiation Oncology (Karadeniz Technical University, Faculty of Medicine, Trabzon, Turkey) with complaints of neck pain and headache. The patients cranial magnetic resonance images showed a 2.5 6-cm mass in the occipital bone, which was subtotally excised. The patient was treated with radiotherapy following the surgery. At present, the patient has shown no progression after 20 months of follow-up.
USLU, GONCA HANEDAN; CANYILMAZ, EMINE; YONEY, ADNAN; AYDIN, SEVDEGUL; SAHBAZ, ASLI; SARI, AHMET
Characterization of the electroclinical features and evolution of childhood occipital epilepsy of Gastaut (COE-G). Seven children were retrospectively identified as having COE-G and were followed-up clinically using EEGs. Visual manifestations were the most common ictal event. Eye-associated ictal deviation was associated with ipsilateral turning of the head and migraine-like symptoms were frequent. Hemiconvulsions occurred in two children, and only one child had secondary generalized tonic-clonic seizures. In all patients, seizures occurred while awake, while two patients also had seizures while sleeping. EEG showed five patients with occipital spike-wave discharges when their eyes were closed which disappeared once their eyes were opened. Two cases continued having frequent seizures despite antiepileptic drug treatment. These patients also displayed learning difficulties and behavioral impairments after seizure onset. COE-G is a distinctive epileptic syndrome; however, the long-term prognosis for patients with the condition is unclear. PMID:23589070
Shu, Xiao Mei; Zhang, Gui Ping; Yang, Bing Zhu; Li, Juan
Migraine is a common clinical disorder, quite disabling and affecting the quality of life in majority of patients. The visual aura is the commonest among all types of aura. Various types of migraine aura described in the literature are photopsia, fortification spectra, scotoma, visual distortion, haemianopia and metamorphsia. The epileptic visual aura differs from aura associated with migraine in certain features: short lasting for 2-3 minutes, occurring in clusters, multicoloured and circular in shape. The ictal manifestations of occipital lobe lesions can mimic episodes of migraine with visual aura according to some reports. In this case report, we intended to highlight aggravation and increased frequency of headache attacks and changed pattern of aura induced by occipital lobe cysticercus granuloma in a patient diagnosed of migraine with aura. The importance of neuroimaging of brain in state of unexpected increased frequency of headache episodes has been emphasised. PMID:22962401
Verma, Rajesh; Lalla, Rakesh
Synaesthesia is a condition in which the input of one sensory modality triggers extraordinary additional experiences. On an explicit level, subjects affected by this condition normally report unidirectional experiences. In grapheme-colour synaesthesia for example, the letter A printed in black may trigger a red colour experience but not vice versa. However on an implicit level, at least for some types of synaesthesia, bidirectional activation is possible. In this study we tested whether bidirectional implicit activation is mediated by the same brain areas as explicit synaesthetic experiences. Specifically, we demonstrated suppression of implicit bidirectional activation with the application of transcranial magnetic stimulation over parieto-occipital brain areas. Our findings indicate that parieto-occipital regions are not only involved in explicit but also implicit synaesthetic binding. PMID:20678509
Rothen, Nicolas; Nyffeler, Thomas; von Wartburg, Roman; Müri, René; Meier, Beat
In head and neck surgery, peripheral sensory nerves are at risk for traumatic injury. These injuries are known to be peripheral triggers of chronic headaches if left untreated or unrecognised. We report the case of a patient that presented with a severe headache, nausea and emesis of 2 years duration following endolymphatic shunt placement for Meniere's disease. Nerve blockade suggested a peripheral trigger, and surgical exploration of the incision site revealed traumatic neuromas of the greater auricular and lesser occipital nerves. Subsequent nerve resection yielded complete symptomatic relief. This is the first case report of a peripherally triggered migraine headache due to the development of neuromas of the greater auricular and lesser occipital nerves, also representing a previously unreported complication of endolymphatic shunt placement. It is recommended that in patients presenting with intractable migraines and a history of head and neck surgery, diagnostic nerve blockage be used to assess for neuromas. PMID:23048004
Vorobeichik, Leon; Fallucco, Michael A; Hagan, Robert R
Twenty patients affected by bilateral occipital cortical-subcortical calcification (BOC) are described, 19 (95%) had epilepsy. In 8 of 16 cases studied, intestinal biopsy revealed coeliac disease. Fourteen patients had occipital partial epilepsy with a relatively benign outcome, while 4 patients were affected by a severe form of epilepsy, with very frequent, drug-resistant, generalised and partial seizures with mental deterioration. One patient had a single episode of convulsive status epilepticus at four months of age. The neurological examination was normal in all patients. CT showed flocculo-nodular, cortico-subcortical BOC, without enhancement and without lobar or hemispheric atrophy. MRI was normal. The clinical and neuroimaging features of these patients are different therefore from those with the Sturge-Weber Syndrome. The study confirms a high prevalence of coliac disease in patients with BOC, but the relationship between these two pathologies still needs to be clarified. Images
Magaudda, A; Dalla Bernardina, B; De Marco, P; Sfaello, Z; Longo, M; Colamaria, V; Daniele, O; Tortorella, G; Tata, M A; Di Perri, R
Two cases of ruptured aneurysms in the posterior cervical regions associated with type-1 neurofibromatosis treated by transcatheter embolization are reported. Patients presented with acute onset of swelling and pain in the affected areas. Emergently performed contrast-enhanced CT demonstrated aneurysms and large hematomas widespread in the posterior cervical regions. Angiography revealed aneurysms and extravasations of the occipital artery. Patients were successfully treated by percutaneous transcatheter arterial microcoil embolization. Transcatheter arterial embolization therapy was found to be an effective method for treating aneurysmal rupture in the posterior cervical regions occurring in association with type-1 neurofibromatosis. A literature review revealed that rupture of an occipital arterial aneurysm, in the setting of neurofibromatosis type 1, has not been reported previously.
Kanematsu, Masayuki; Kato, Hiroki; Kondo, Hiroshi; Goshima, Satoshi; Tsuge, Yusuke; Kojima, Toshiaki; Watanabe, Haruo [Gifu University Hospital, Department of Radiology (Japan)
The history of clinical frontal lobe study is long and rich which provides valuable insights into neuropsychologic determinants of functions of prefrontal cortex (PFC). PFC is often classified as multimodal association cortex as extremely processed information from various sensory modalities is integrated here in a precise fashion to form the physiologic constructs of memory, perception, and diverse cognitive processes. Human neuropsychologic studies also support the notion of different functional operations within the PFC. The specification of the component ‘executive’ processes and their localization to particular regions of PFC have been implicated in a wide variety of psychiatric disorders.
Siddiqui, Shazia Veqar; Chatterjee, Ushri; Kumar, Devvarta; Siddiqui, Aleem; Goyal, Nishant
The juvenile occipital bone from the site of Malladetes in Valencia (Spain) is described and compared with other European Pleistocene representatives of the genus Homo. This specimen derives from a Gravettian cultural context and has been AMS radiocarbon-dated to 25,120±240 years bp. As such, it provides evidence on early modern human anatomy from the Central Mediterranean region of the Iberian
Juan Luis Arsuaga; Valent??n Villaverde; Rolf Quam; Ana Gracia; Carlos Lorenzo; Ignacio Mart??nez; José-Miguel Carretero
Many reports have described the presence of alopecia areata (AA) associated with other autoimmune diseases, which support the autoimmune nature of AA. Additionally, AA has been reported in association with malignancy as a paraneoplastic symptom. In this report, we describe three patients with diffuse large B-cell lymphoma, alveolar soft part sarcoma, and cavernous sinus arteriovenous fistula with embolization treatment, respectively, who characteristically presented with rectangular-patterned occipital AA.
Shin, Jaeyong; Jang, Hong Sun; Cho, Sung Bin
A woman having common migraine attacks coincident with an asymmetrical bilateral occipital lobe infarction that spared the brainstem and cerebellum underwent these studies: serial electroencephalography, brainstem auditory, visual and somatosensory evoked potentials, magnetic resonance imaging of the brain and cerebral arteriography. The patient's vision improved greatly during a one-year follow-up. The absence of risk factors for stroke suggested that migraine caused the infarction in the posterior circulation network. The pathophysiological mechanisms of stroke in migraine remains speculative. PMID:1526769
Ganji, S; Williams, W; Furlow, J
Objective To provide an overview of atlanto-occipital dislocation and associated occipital condyle fractures so as to alert physicians to this rare injury and potentially improve patient outcome. The pertinent anatomy, mechanism of injury, clinical and radiologic evaluation and the management of these rare injuries are discussed in an attempt to alert physicians to this type of injury and to improve outcome. Data sources The data were obtained from a MEDLINE search of the English literature from 1966 to 1999 and the experience of 4 spine surgeons at a quaternary care acute spinal cord injury unit. Study selection Detailed anatomic and epidemiologically sound radiology studies were identified and analyzed. Only small retrospective studies or case series were available in the literature. Data extraction Valid anatomic, biomechanical and radiologic evaluation was extracted from studies. Clinical data came from limited studies and expert opinion. Data synthesis Early diagnosis is essential and is facilitated by a detailed clinical examination and strict adherence to an imaging algorithm that includes CT and MRI scanning. When the dislocation is identified, timely gentle reduction and prompt stabilization throuigh nonoperative or operative means is found to optimize patient outcome. Conclusions Atlanto-occipital dislocation should be suspected in any patient involved in a high speed motor vehicle or pedestrian collision. Once suspected, proper imaging and appropriate management of these once fatal injuries can improve survival and neurologic outcome.
Fisher, Charles G.; Sun, John C.L.; Dvorak, Marcel
Neuropsychological deficits after occipital infarction are most often described in case studies and only a small sample of studies has attempted to exactly correlate the anatomical localization of lesions with associated neuropsychological symptoms. The present study investigated a large number of patients (N = 128) in order to provide an overview of neurological and neuropsychological deficits after occipital, occipito-temporal and occipito-parietal infarction. A particular approach of the study was to define exact anatomical correlates of neuropsychological dysfunction by using voxel-based lesion-symptom mapping (VLSM) in 61 patients. In addition to a visual field defect and phosphenes, patients often reported anomia, difficulties in reading and memory deficits. Visual disorders, such as achromatopsia, akinetopsia or prosopagnosia, were rarely reported by the patients. Memory and visual disorders were diagnosed efficiently using simple clinical screening tests, such as the Rey-Osterrieth Complex Figure Test for immediate recall, the Demtect and the Lang Stereo Test. Visual field defects, reading disorders and the perception of phosphenes were associated primarily with lesions of the calcarine sulcus. Anomia and memory deficits were related to lesions of the occipital inferior gyrus, the lingual gyrus and hippocampus, as well as to lesions of principal white matter tracts. PMID:23206528
Kraft, Antje; Grimsen, Cathleen; Kehrer, Stefanie; Bahnemann, Markus; Spang, Karoline; Prass, Maren; Irlbacher, Kerstin; Köhnlein, Martin; Lipfert, Anika; Brunner, Freimuth; Kastrup, Andreas; Fahle, Manfred; Brandt, Stephan A
Charles Bonnet syndrome is a condition characterized by visual hallucinations. These simple or complex visual hallucinations are more common in elderly individuals with impaired peripheral vision. The current report describes a case of transient Charles Bonnet syndrome appearing after the removal of a meningioma. The patient was a 61-year-old man who already had impaired visual acuity due to diabetic retinopathy. Brain MRI revealed a cystic tumor severely compressing the right occipital lobe. Starting on day 2 postoperatively, the patient was troubled by recurring visual hallucinations involving people, flowers, pictures, and familiar settings(the train and a coffee shop). These continued for 3.5 months. This period roughly coincided with the time for the occipital lobe to recover from the compression caused by the tumor, a fact that was confirmed by several MRI scans. 123I-IMP SPECT performed 1 month after the surgical operation showed an area of hypoperfusion in the right parieto-occipital lobe. Based on the patient's clinical course and MRI findings, the mechanism of onset of visual hallucinations in this patient was put forward. The release of pressure in the brain by tumor removal and subsequent recovery changed the blood flow to the brain. This triggered visual hallucinations in the patient, who was already predisposed to developing Charles Bonnet syndrome because of diabetic retinopathy. This case is interesting since it indicates that central neurological factors, as well as visual deficits, may induce the appearance of visual hallucinations in Charles Bonnet syndrome. PMID:24807549
Arai, Takao; Hasegawa, Yuzuru; Tanaka, Toshihide; Kato, Naoki; Watanabe, Mitsuyoshi; Nakamura, Aya; Murayama, Yuichi
Functional networks in the human brain have been investigated using electrophysiological methods (EEG/MEG, LFP, and MUA) and steady-state paradigms that apply periodic luminance or contrast modulation to drive cortical networks. We have used this approach with fMRI to characterize a cortical network driven by a checkerboard reversing at a fixed frequency. We found that the fMRI signals in voxels located in occipital cortex were increased by checkerboard reversal at frequencies ranging from 3 to 14 Hz. In contrast, the response of a cluster of voxels centered on basal medial frontal cortex depended strongly on the reversal frequency, consistently exhibiting a peak in the response for specific reversal frequencies between 3 and 5 Hz in each subject. The fMRI signals at the frontal voxels were positively correlated indicating a homogeneous cluster. Some of the occipital voxels were positively correlated to the frontal voxels apparently forming a large-scale functional network. Other occipital voxels were negatively correlated to the frontal voxels, suggesting a functionally distinct network. The results provide preliminary fMRI evidence that during visual stimulation, input frequency can be varied to engage different functional networks.
Srinivasan, Ramesh; Fornari, Eleonora; Knyazeva, Maria G.; Meuli, Reto; Maeder, Philippe
We have examined the activity levels produced in various areas of the human occipital cortex in response to various motion stimuli using functional magnetic resonance imaging (fMRI) methods. In addition to standard luminance-defined (first-order) motion, three types of second-order motion were used. The areas examined were the motion area V5 (MT) and the following areas that were delineated using retinotopic
Andrew T. Smith; Mark W. Greenlee; Krish D. Singh; Falk M. Kraemer; Jurgen Hennig
Right hemisphere dominance in face processing is well established and unilateral right inferior temporo-occipital damage can result in prosopagnosia. Here, we describe a 21-year-old right-handed woman with acute impairment in face recognition that selectively concerned unfamiliar faces, following a focal left lateral temporo-occipital venous infarct. She was severely impaired in discerning that unknown people seen in everyday life were unfamiliar,
Patrik Vuilleumier; Christine Mohr; Nathalie Valenza; Corinne Wetzel; Theodor Landis
It remains unclear to what extent retinotopic maps can undergo large-scale plasticity following damage to human visual cortex. The literature has predominately focused on retinotopic changes in patients with retinal pathologies or congenital brain malformations. Yet, damage to the adult visual cortex itself is common in cases such as stroke, tumor, or trauma. To address this issue, we used a unique database of fMRI vision maps in patients with adult-onset (n = 25) and congenital (n = 2) pathology of the visual cortex. We identified atypical retinotopic organization in three patients (two with adult-onset, and one with congenital pathology) consisting of an expanded ipsilateral field representation that was on average 3.2 times greater than healthy controls. The expanded representations were located at the vertical meridian borders between visual areas such as V1/V2. Additionally, two of the three patients had apparently an ectopic (topographically inconsistent) representation of the ipsilateral field within lateral occipital cortex that is normally associated with visual areas V3/V3A (and possibly other areas). Both adult-onset cases had direct damage to early visual cortex itself (rather than to the afferent drive only), resulting in a mostly nonfunctional hemisphere. The congenital case had severe cortical malformation of the visual cortex and was acallosal. Our results are consistent with a competitive model in which unilateral damage to visual cortex or disruption of the transcallosal connections removes interhemispheric suppression from retino-geniculate afferents in intact visual cortex that represent the vertical meridian and ipsilateral visual field.
Mathis, Jedidiah; Ulmer, John L.; Mueller, Wade; Maciejewski, Mary J.; DeYoe, Edgar A.
This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can induce a phenomenon analogous to blindsight in which conscious detection is impaired while the ability to discriminate ‘unseen’ stimuli is preserved above chance. Here we sought to reproduce this phenomenon using offline occipital cTBS, which has been shown to induce an inhibitory cortical aftereffect lasting 45–60 minutes. Contrary to expectations, our first experiment revealed the opposite effect: cTBS enhanced conscious vision relative to a sham control. We then sought to replicate this cTBS-induced potentiation of consciousness in conjunction with magnetoencephalography (MEG) and undertook additional experiments to assess its relationship to visual cortical excitability and levels of the inhibitory neurotransmitter ?-aminobutyric acid (GABA; via magnetic resonance spectroscopy, MRS). Occipital cTBS decreased cortical excitability and increased regional GABA concentration. No significant effects of cTBS on MEG measures were observed, although the results provided weak evidence for potentiation of event related desynchronisation in the ? band. Collectively these experiments suggest that, through the suppression of noise, cTBS can increase the signal-to-noise ratio of neural activity underlying conscious vision. We speculate that gating-by-inhibition in the visual cortex may provide a key foundation of consciousness.
Allen, Christopher P. G.; Dunkley, Benjamin T.; Muthukumaraswamy, Suresh D.; Edden, Richard; Evans, C. John; Sumner, Petroc; Singh, Krish D.; Chambers, Christopher D.
Dementia with Lewy bodies (DLB) is often associated with occipital hypometabolism or hypoperfusion, as well as deficits in cholinergic neurotransmission. In this study, 11 mild DLB, 16 mild AD and 16 age-matched controls underwent arterial spin-labeled perfusion MRI (ASL-pMRI) and neuropsychological testing. Patterns of cerebral blood flow (CBF) and cognitive performance were compared. In addition, combined ASL-pMRI and ChEI drug challenge (pharmacologic MRI) was tested as a probe of cholinergic function in 4 of the DLB participants. Frontal and parieto-occipital hypoperfusion was observed in both DLB and AD but was more pronounced in DLB. Following ChEI treatment, perfusion increased in temporal and parieto-occipital cortex, and cognitive performance improved on a verbal fluency task. If confirmed in a larger study, these results provide further evidence for brain cholinergic dysfunction in DLB pathophysiology, and use of pharmacologic MRI as an in vivo measure of cholinergic function. PMID:20924800
Fong, Tamara G; Inouye, Sharon K; Dai, Weiying; Press, Daniel Z; Alsop, David C
A number of behavioral and neuroimaging studies have reported converging data in favor of a cortical network for vestibular function, distributed between the temporo-parietal cortex and the prefrontal cortex in the primate. In this review, we focus on the role of the cerebral cortex in visuo-vestibular integration including the motion sensitive temporo-occipital areas i.e., the middle superior temporal area (MST) and the parietal cortex. Indeed, these two neighboring cortical regions, though they both receive combined vestibular and visual information, have distinct implications in vestibular function. In sum, this review of the literature leads to the idea of two separate cortical vestibular sub-systems forming (1) a velocity pathway including MST and direct descending pathways on vestibular nuclei. As it receives well-defined visual and vestibular velocity signals, this pathway is likely involved in heading perception and rapid top-down regulation of eye/head coordination and (2) an inertial processing pathway involving the parietal cortex in connection with the subcortical vestibular nuclei complex responsible for velocity storage integration. This vestibular cortical pathway would be implicated in high-order multimodal integration and cognitive functions, including world space and self-referential processing.
Transcranial electrical stimulation (tES) is a promising therapeutic tool for a range of neurological diseases. Understanding how the small currents used in tES spread across the scalp and penetrate the brain will be important for the rational design of tES therapies. Alternating currents applied transcranially above visual cortex induce the perception of flashes of light (phosphenes). This makes the visual system a useful model to study tES. One hypothesis is that tES generates phosphenes by direct stimulation of the cortex underneath the transcranial electrode. Here, we provide evidence for the alternative hypothesis that phosphenes are generated in the retina by current spread from the occipital electrode. Building on the existing literature, we first confirm that phosphenes are induced at lower currents when electrodes are placed farther away from visual cortex and closer to the eye. Second, we explain the temporal frequency tuning of phosphenes based on the well-known response properties of primate retinal ganglion cells. Third, we show that there is no difference in the time it takes to evoke phosphenes in the retina or by stimulation above visual cortex. Together, these findings suggest that phosphenes induced by tES over visual cortex originate in the retina. From this, we infer that tES currents spread well beyond the area of stimulation and are unlikely to lead to focal neural activation. Novel stimulation protocols that optimize current distributions are needed to overcome these limitations of tES.
Bright light can cause excessive visual discomfort, referred to as photophobia. The precise mechanisms linking luminance to the trigeminal nociceptive system supposed to mediate this discomfort are not known. To address this issue in healthy human subjects we modulated differentially visual cortex activity by repetitive transcranial magnetic stimulation (rTMS) or flash light stimulation, and studied the effect on supraorbital pain thresholds and the nociceptive-specific blink reflex (nBR). Low frequency rTMS that inhibits the underlying cortex, significantly decreased pain thresholds, increased the 1st nBR block ipsi- and contralaterally and potentiated habituation contralaterally. After high frequency or sham rTMS over the visual cortex, and rMS over the right greater occipital nerve we found no significant change. By contrast, excitatory flash light stimulation increased pain thresholds, decreased the 1st nBR block of ipsi- and contralaterally and increased habituation contralaterally. Our data demonstrate in healthy subjects a functional relation between the visual cortex and the trigeminal nociceptive system, as assessed by the nociceptive blink reflex. The results argue in favour of a top-down inhibitory pathway from the visual areas to trigemino-cervical nociceptors. We postulate that in normal conditions this visuo-trigeminal inhibitory pathway may avoid disturbance of vision by too frequent blinking and that hypoactivity of the visual cortex for pathological reasons may promote headache and photophobia.
Sava, Simona L.; de Pasqua, Victor; Magis, Delphine; Schoenen, Jean
The ability to use rules or principles allows behavior to generalize from specific circumstances. We have previously shown that such rules are encoded in the lateral prefrontal cortex (PFC) and premotor cortex (PMC). Here, we extend these investigations to two other areas directly connected with the PFC and the PMC, the inferior temporal cortex (ITC) and the dorsal striatum (STR).
Rahmat Muhammad; Jonathan D. Wallis; Earl K. Miller
Reasoning is a key component of adaptable “executive” behavior and is known to depend on a network of frontal and parietal brain regions. However, the mechanisms by which this network supports reasoning and adaptable behavior remain poorly defined. Here, we examine the relationship between reasoning, executive control, and frontoparietal function in a series of nonverbal reasoning experiments. Our results demonstrate that, in accordance with previous studies, a network of frontal and parietal brain regions is recruited during reasoning. Our results also reveal that this network can be fractionated according to how different subregions respond when distinct reasoning demands are manipulated. While increased rule complexity modulates activity within a right lateralized network including the middle frontal gyrus and the superior parietal cortex, analogical reasoning demand—or the requirement to remap rules on to novel features—recruits the left inferior rostrolateral prefrontal cortex and the lateral occipital complex. In contrast, the posterior extent of the inferior frontal gyrus, associated with simpler executive demands, is not differentially sensitive to rule complexity or analogical demand. These findings accord well with the hypothesis that different reasoning demands are supported by different frontal and parietal subregions.
Thompson, Russell; Duncan, John; Owen, Adrian M.
? Abstract The discovery and analysis of cortical visual areas is a major accom- plishment of visual neuroscience. In the past decade the use of noninvasive,functional imaging, particularly functional magnetic resonance imaging (fMRI), has dramatically increased our detailed knowledge,of the functional organization of the human,visual cortex and its relation to visual perception. The fMRI method,offers a major advantage over other
Kalanit Grill-Spector; Rafael Malach
The purpose of this study was to identify the incidence of neuropathic pain occurring after radiofrequency neurotomy of the third occipital nerve (TON). This study was conducted at a teaching hospital from January 1, 2008, to March 31, 2010. With institutional review board approval, Current Procedural Terminology codes were used to identify patients who received radiofrequency ablation (RFA) of the nerves supplying the C2-3 facet joint and the TON. The C3 dorsal ramus provides innervation to the C2-3 facet joint and the suboccipital cutaneous region, and procedures that included ablation to this region were reviewed for complications. Postprocedural data were collected by reviewing follow-up appointment notes and telephone calls. Included were patients who had new neuropathic pain in the distribution of the TON after RFA. They described what they were feeling as burning, tingling, or numbness. All patients who presented with complaints had normal neurologic findings and no secondary cause for their symptoms. The included patient medical records were then reviewed for severity and duration of symptoms and the need for treatment with pain medication. Sixty-four patients underwent C2-3 RFA or TON RFA, and 12 patients were identified as experiencing ablation-induced third occipital neuralgia, an incidence rate of 19%. This finding suggests that patients undergoing RFA of the nerves supplying the C2-3 joint or TON are at risk for postprocedural third occipital neuralgia. This possibility may affect providing informed consent as well as anticipating and managing postprocedural pain.
Gazelka, Halena M; Knievel, Sarah; Mauck, William D; Moeschler, Susan M; Pingree, Matthew J; Rho, Richard H; Lamer, Tim J
The Pax-1 gene has been found to play an important role in the development of the vertebral column. The cervico-occipital transitional zone is a specialized region of the vertebral column, and malformations of this region have frequently been described in humans. The exact embryonic border between head and trunk is a matter of controversy. In order to determine a possible role of Pax-1 in the development of the cervico-occipital transitional zone we studied the expression of this gene in a series of quail embryos and murine fetuses with in situ hybridization and immunohistochemistry. Pax-1 is expressed in all somites of the embryo, including the first five occipital ones. During embryonic days 3-5 the gene is down-regulated in the caudal direction within the first five somites, whereas more caudally Pax-1 is strongly expressed in the cells of the perinotochordal tube. In 5-day-old quail embryos, the cartilaginous anlage of the basioccipital bone has developed and ther is no more expression of Pax-1 in this region. The fusion of the dens axis with the body of the axis also coincides with switching off of the Pax-1 gene. More caudally, the gene is continuously expressed in the intervertebral discs of murine embryos and therefore seems to be important for the process of resegmentation. Quail embryos do not possess permanent intervertebral discs. ¿Hyper-¿ or ¿hyposegmentation¿ defects may be explained by an over- or under-expression of Pax-1 during development. We also reinvestigated the border between the head and trunk in chick embryos by performing homotopical grafting experiments of the 5th somite between chick and quail embryos. PMID:8651506
Wilting, J; Ebensperger, C; Müller, T S; Koseki, H; Wallin, J; Christ, B
Blind individuals often demonstrate enhanced nonvisual perceptual abilities. However, the neural substrate that underlies this improved performance remains to be fully understood. An earlier behavioral study demonstrated that some early-blind people localize sounds more accurately than sighted controls using monaural cues. In order to investigate the neural basis of these behavioral differences in humans, we carried out functional imaging studies using positron emission tomography and a speaker array that permitted pseudo-free-field presentations within the scanner. During binaural sound localization, a sighted control group showed decreased cerebral blood flow in the occipital lobe, which was not seen in early-blind individuals. During monaural sound localization (one ear plugged), the subgroup of early-blind subjects who were behaviorally superior at sound localization displayed two activation foci in the occipital cortex. This effect was not seen in blind persons who did not have superior monaural sound localization abilities, nor in sighted individuals. The degree of activation of one of these foci was strongly correlated with sound localization accuracy across the entire group of blind subjects. The results show that those blind persons who perform better than sighted persons recruit occipital areas to carry out auditory localization under monaural conditions. We therefore conclude that computations carried out in the occipital cortex specifically underlie the enhanced capacity to use monaural cues. Our findings shed light not only on intermodal compensatory mechanisms, but also on individual differences in these mechanisms and on inhibitory patterns that differ between sighted individuals and those deprived of vision early in life.
Gougoux, Frederic; Zatorre, Robert J; Lassonde, Maryse; Voss, Patrice
Occipital dermal sinuses (ODSs) are congenital lesions located in the midline and characterized by a cutaneous pit or dimple. The intracranial extension as well as the associated symptoms are variable. To date, a familial occurrence of these lesions has not been reported. In this paper the authors report on a 2-year-old boy with an ODS and intracranial hypertension. The boy's mother had a similar lesion but did not have any complaints. Following their experience with this case and a literature review, the authors suggest that there may be a genetic basis in certain instances of ODS. PMID:17328285
Ansari, Saeed; Dadmehr, Majid; Nejat, Farideh
This is a case study presented by the University of Pittsburgh Department of Pathology in which a 32-year-old man with symptoms of an upper respiratory infection presented himself to the hospital with mental status changes and a severe occipital headache of two days duration. Visitors are given both the microscopic description and radiology results, including images, and are given the opportunity to diagnose the patient. This is an excellent resource for students in the health sciences to familiarize themselves with using patient history and laboratory results to diagnose disease. It is also a helpful site for educators to use to introduce or test student learning in neuropathology.
Grossman, Robert I.; Lavi, Ehud; Lieberman, Andrew P.
CX-516 is one of a series of AMPA modulators under development by Cortex, in collaboration with Shire and Servier, for the potential treatment of Alzheimer's disease (AD), schizophrenia and mild cognitive impairment (MCI) . By June 2001, CX-516 was in phase II trials for both schizophrenia and attention deficit hyperactivity disorder (ADHD) . A phase II trial in fragile X syndrome and autism was expected to start in May 2002 . In October 2001, Cortex was awarded a Phase II SBIR grant of $769,818 from the National Institutes of Mental Health to investigate the therapeutic potential of AMPAkines in schizophrenia. This award was to support a phase IIb study of CX-516 as a combination therapy in schizophrenia patients concomitantly treated with olanzapine. The trial was to enroll 80 patients and employ a randomized, double-blind, placebo-controlled design in which the placebo group was to receive olanzapine plus placebo and the active group was to receive olanzapine plus CX-516 . In April 2000, Shire and Cortex signed an option agreement in which Shire was to evaluate CX-516for the treatment of ADHD. Under the terms of the agreement, Shire would undertake a double-blind, placebo-controlled evaluation of CX-516 involving ADHD patients. If the study proved effective, Shire would have the right to convert its option into an exclusive worldwide license for the AMPAkines for ADHD under a development and licensing agreement. Should Shire elect to execute this agreement, Shire would bear all future developmental costs . By February 2002, Cortex and Servier had revealed their intention to begin enrolment for an international study of an AMPAkine compound as a potential treatment for MCI in the near future. Assuming enrollment proceeded as anticipated, results were expected during the second quarter of 2003 . By May 2002, phase II trials were underway . In March 2002, Cortex was awarded extended funding under the University of California BioSTAR projectfor the research project: 'Ampakine modulation of brain neurotrophin expression: a novel therapeutic strategy'. This funding was expected to amount to $193,000 over a two-year period . PMID:12186271
Chronic subdural hematoma (CSH) is a common disease that is treated with burr hole drainage by neurosurgeons. The outcome of CSH is mostly favorable. We treated 2 cases with bilateral occipital lobe infarction due to CSH. A 57-year-old woman was ambulatory when she visited a clinic for evaluation of headache. One hour after the CT was taken, she developed acute impairment of consciousness, so that she was referred to our hospital. The second patient was a 73-year-old woman with a history of depression who was involved in a traffic accident 5 weeks before admission to our hospital. She was at first admitted to a psychiatric hospital for evaluation of gait disturbance. Three weeks after she was admitted to the psychiatric hospital, she fell into a coma. She was referred to our hospital. Their brain CT on admission revealed compressed ambient and interpeduncular cistern and bilateral CSH. Although burr hole drainage surgery was performed, the 2 patients developed severe sequelae due to occipital lobe infarction caused by central transtentorial herniation. PMID:23542794
Kudo, Kanae; Naraoka, Masato; Shimamura, Norihito; Ohkuma, Hiroki
Secondary to the increase in deformational plagiocephaly a growing number of infants with cranial deformity present to craniofacial teams. Computed tomography (CT) is diagnostic, but uses ionizing radiation. The purpose of this study was to evaluate ultrasound as a screening test for the patency of cranial sutures in scaphocephaly and occipital plagiocephaly. The cranial sutures of 54 infants with this cranial deformity were assessed by ultrasound. Sutures were read as patent or fused if a hypoechoic gap could or could not be demonstrated between the hyperechoic clavarial bones, respectively. Seven children suffered from true craniosynostosis of either the sagittal or the lambdoid suture. In five cases the ultrasound findings were diagnostic for a fused suture, in two cases the results were inconclusive. Forty-seven infants presented with deformational plagiocephaly. Ultrasound examination demonstrated patent sutures in 45 cases and was inconclusive in two cases. Sonography of the cranial sutures is a good screening tool to distinguish fused from patent cranial sutures in scaphocephaly and occipital plagiocephaly and avoids the radiation exposure associated with CT examinations. PMID:22510342
Krimmel, M; Will, B; Wolff, M; Kluba, S; Haas-Lude, K; Schaefer, J; Schuhmann, M U; Reinert, S
Stimulus inversion impairs face discrimination to a greater extent than discrimination of other non-face object categories. This finding has led to suggestions that upright faces are represented by mechanisms specialized for upright faces whereas inverted face representation depends on more general object recognition mechanisms. In the present study we tested the causal role of face-selective and object-selective cortical areas for upright and inverted face discrimination by transiently disrupting neural processing using transcranial magnetic stimulation (TMS). Participants matched upright and inverted faces while TMS was delivered over each participant's functionally localized right occipital face area (rOFA) or right lateral occipital area (rLO). TMS delivered over rOFA disrupted the discrimination of upright and inverted faces while TMS delivered over rLO impaired inverted face discrimination only. These results provide causal evidence that upright faces are represented by face-specific mechanisms whereas inverted faces are represented by both face-specific and object-specific mechanisms. The similar sensitivity of the OFA to upright and inverted faces is consistent with the hypothesis that the OFA processes facial features at an early stage of face processing. PMID:21896279
Pitcher, David; Duchaine, Bradley; Walsh, Vincent; Yovel, Galit; Kanwisher, Nancy
To delineate further the clinical spectrum of Menkes disease, an X-linked recessive disorder of copper transport, we studied 4 related males, ranging in age from 4-38 years, with a unique phenotype that combines manifestations of classical and mild Menkes disease and occipital horn syndrome (OHS). The propositus, an 18-year-old man, was evaluated following an intracerebral hemorrhage at age 15 years and was noted to have marked hypotonia, motor delay with mental retardation, bladder diverticula, failure to thrive, and diarrhea from infancy; seizures from age 3 years; and abnormal hair (pili torti) and face, cutis laxa, and multiple joint dislocations. Radiographic abnormalities included occipital exostoses, tortuous cerebral blood vessels with multiple branch occlusions, and hammer-shaped clavicles. Biochemical studies demonstrated reduced copper and ceruloplasmin levels in serum, and abnormal plasma catecholamine ratios. We reported previously the molecular defect in this family, a splice-site mutation that predicts formation of approximately 20% of the normal Menkes gene product. Here, we detail the clinical course and physical features and radiographic findings in these 4 individuals, and compare their phenotype with classical and mild Menkes and OHS. Unusual Menkes disease variants such as this may escape recognition due to anomalies that appear inconsistent with the diagnosis, particularly prolonged survival and later onset of seizures. Males with mental retardation and connective tissue abnormalities should be evaluated for biochemical evidence of defective copper transport. 28 refs., 8 figs.
Proud, V.K.; Mussell, H.G.; Percy, A.K. [Univ. of Alabama School of Medicine, Birmingham, AL (United States)] [and others] [Univ. of Alabama School of Medicine, Birmingham, AL (United States); and others
A 56-year-old man presented with a 6-mo history of headache. Although neurological and laboratory examinations were normal, computed tomography (CT) scan was performed which revealed multiple occipital osteolytic lesions, which were suspected to be multiple myeloma. Subsequently nuclear magnetic resonance imaging (MRI) showed that these lesions presented with a cerebrospinal fluid (CSF)-like signal intensity, no diffusional restriction and intrinsic mass-like enhancement on conventional sequences were seen. T2 relaxation time was similar to that of CSF in the ventricles and adjacent subarachnoid space on T2-mapping. Single photon emission CT with 99mTc-Methyl diphosphonate was performed which revealed no increased radiotracing accumulation. Finally, these lesions were diagnosed as mutiple arachnoid granulations (AGs). The headache was treated symptomatically with medical therapy. On follow up examination after 6 mo no evidence of tumor was detected. This report aimed to illustrate the appearance and differentiation of occipital defects caused by multiple AGs on CT and MRI, with emphasis on the findings from T2 mapping.
Lu, Chao-Xuan; Du, Yong; Xu, Xiao-Xue; Li, Yang; Yang, Han-Feng; Deng, Shao-Qiang; Xiao, Dong-Mei; Li, Bing; Tian, Yun-Hong
Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC. PMID:22356730
Le, Tien V; Burkett, Clint; Ramos, Edwin; Uribe, Juan S
Activity of the human visual cortex, elicited by steady-state flickering at 8Hz, is non-invasively probed by multi-speckle diffusingwave spectroscopy (DWS). Parallel detection of the intensity fluctuations of statistically equivalent, but independent speckles allows to resolve stimulation-induced changes in the field autocorrelation of multiply scattered light of less than 2%. In a group of 9 healthy subjects we find a faster decay of the field autocorrelation function during the stimulation periods for data measured with a long-distance probe (30mm source-receiver distance) at 2 positions over the occipital cortex (t-test: t(8) = -2.672, p = 0.028 < 0.05 for position 1, t(8) = -2.874, p = 0.021 < 0.05 for position 2). In contrast, no statistically significant change is seen when a short-distance probe (16mm source-receiver distance) is used (t-test: t(8) = -2.043, p = 0.075 > 0.05 for position 1, t(8) = -2.146, p = 0.064 > 0.05 for position 2). The enhanced dynamics observed with DWS is positively correlated with the functional increase of blood volume in the visual cortex, while the heartbeat rate is not affected by stimulation. Our results indicate that the DWS signal from the visual cortex is governed by the regional cerebral blood flow velocity.
Jaillon, Franck; Li, Jun; Dietsche, Gregor; Elbert, Thomas; Gisler, Thomas
The venous variations of the galenic system were evaluated using three-dimensional computed tomography angiography (3D-CTA) to assess the influence on the occipital transtentorial approach in 150 patients who underwent 3D-CTA as a routine screening examination for cerebrovascular diseases. The variations of the vein of Galen with its tributaries, the tentorial sinus, and the veins around the tentorium were evaluated in multiple intensity projections and stereoscopic images. The angle between the vein of Galen and the straight sinus was 67.1 +/- 31.9 degrees (mean +/- SD). Observation of the pineal body from the direction of the approach tended to extend to the quadrigeminal bodies in acute angle cases, and to the third ventricle in obtuse angle cases. Bilateral internal cerebral veins (ICVs) joined in the anterior portion were associated with a long vein of Galen, or in the posterior portion with a short vein of Galen. The distance between the bilateral ICVs was 4.66 +/- 2.28 mm (mean +/- SD), and the shape of the space could be classified as spindle, parallel, hairpin, and round types. The basal vein could be classified into well-developed, hypoplastic, hardly recognized, and mimicking two basal veins because the tributary did not join but ran parallel to the basal vein. The drainage pathways lead to the anterior or posterior portion of the vein of Galen, the ICV, the tentorial sinus, and the superior petrosal sinus. The various types of the tentorial sinus and primitive tentorial sinus which might be sacrificed during section of the tentorium were confirmed. The inferior cerebral vein draining to the tentorial sinus could be seen. 3D-CTA could also demonstrate the presence, the course, and the drainage points of the internal occipital vein, the precentral cerebellar vein, the posterior pericallosal vein, and so on. 3D-CTA is useful to evaluate the variations of the venous system and the relationship with the tumor, and for preoperative simulation and intraoperative navigation of the occipital transtentorial approach. PMID:16127255
Suzuki, Yasuhiro; Nakajima, Masateru; Ikeda, Hisato; Abe, Takumi
Background Latissimus dorsi (LD) myocutaneous flap is a popular method of breast reconstruction which can be associated with high incidence of seroma formation. Quilting sutures at the harvest site are used to reduce this. Barbed sutures are self anchoring sutures which avoid multiple knotting and can be useful in quilting. Methods A retrospective analysis of prospectively maintained database of patients who underwent LD flap breast reconstruction between January 2009 and January 2011 was carried out. Seroma formation at the harvest site, wound related complications, inpatient stay and duration of surgery were analysed and a comparison was made between two groups where quilting was done with barbed (V-Loc) suture and conventional polydioxanone (PDS) II sutures. Results Fifty-seven patients were included of which 33 had quilting by V-Loc sutures and in 24 patients PDS II suture was used. Median age in the PDS group was 55 years (interquartile range [IQR)], 45 to 61 years) which was comparable to the V-Loc group (53 years [IQR, 48 to 59 years]; P-value 0.948). Sixteen patients (28%) had significant seroma formation and 5 (9%) patients developed superficial wound dehiscence. Incidences of seroma or wound complications were comparable (P-value 0.378 and 1.00, respectively). Secondary outcomes such as total duration of surgery, total inpatient stay, total amount of drain at the donor site were also similar in two groups. Conclusions Use of barbed sutures for quilting the donor site in LD flap reconstruction is a feasible option and the associated seroma formation and wound complications are comparable with conventional sutures.
Hussain, Tasadooq; Mahapatra, Tapan Kumar; McManus, Penelope Louise; Kneeshaw, Peter John
Objective: We compared polyglecaprone (Monocryl®) and bidirectional barbed (V-Loc® 180) running sutures during urethrovesial anastomosis (UVA) in laparoscopic radical prostatectomy (LRP). Materials and methods: A total of 92 consecutive patients underwent extraperitoneal LRP for prostate cancer. In the first 47 patients, the running UVA was performed using 3-0 monofilament polyglecaprone (Monocryl®) suture (Group 1). In the subsequent 45 patients, the running UVA was performed with the 3-0 barbed suture (V-Loc® 180) (Group 2). Rhabdosphincter reconstruction was performed in all the patients. Results: The mean prostatectomy time was 196 and 179 minutes in Group 1 and 2, respectively (p < 0.001). Moreover, the mean UVA time was 40 and 24 minutes in Group 1 and 2, respectively (p < 0.001). Also, catheterization time, lenght of hospital stay and the number of the patients with urine leakage were significantly lower in Group 2 than the other (p < 0.001). No patients in V-Loc® 180 suture group and 5 patients in Monocryl® suture group experienced postoperative drain leakage in the present study. Overall pad usage at 6th month was higher in group 1 than the other group. In group 1 and 2, 78.7% and 93.3% of the patients reported 0 to 1 pads daily, whereas 21.3% and 6.7% reported ? 2 pads daily (p = 0.002). Conclusions: We therefore consider that use of barbed suture running UVA during LRP is associated with a significantly shorter operative time maintaining a proper suturing tension compared with standard suture and it is not associated with a higher incidence of adverse events with no postoperative complications. PMID:25017586
Arslan, Murat; Tuncel, Altug; Aslan, Yilmaz; Kozacioglu, Zafer; Gunlusoy, Bulent; Atan, Ali
Single-cell studies in the macaque have reported selective neural responses evoked by visual presentations of faces and bodies. Consistent with these findings, functional magnetic resonance imaging studies in humans and monkeys indicate that regions in temporal cortex respond preferentially to faces and bodies. However, it is not clear how these areas correspond across the two species. Here, we directly compared category-selective areas in macaques and humans using virtually identical techniques. In the macaque, several face- and body part-selective areas were found located along the superior temporal sulcus (STS) and middle temporal gyrus (MTG). In the human, similar to previous studies, face-selective areas were found in ventral occipital and temporal cortex and an additional face-selective area was found in the anterior temporal cortex. Face-selective areas were also found in lateral temporal cortex, including the previously reported posterior STS area. Body part-selective areas were identified in the human fusiform gyrus and lateral occipitotemporal cortex. In a first experiment, both monkey and human subjects were presented with pictures of faces, body parts, foods, scenes, and man-made objects, to examine the response profiles of each category-selective area to the five stimulus types. In a second experiment, face processing was examined by presenting upright and inverted faces. By comparing the responses and spatial relationships of the areas, we propose potential correspondences across species. Adjacent and overlapping areas in the macaque anterior STS/MTG responded strongly to both faces and body parts, similar to areas in the human fusiform gyrus and posterior STS. Furthermore, face-selective areas on the ventral bank of the STS/MTG discriminated both upright and inverted faces from objects, similar to areas in the human ventral temporal cortex. Overall, our findings demonstrate commonalities and differences in the wide-scale brain organization between the two species and provide an initial step toward establishing functionally homologous category-selective areas. PMID:19225169
Pinsk, Mark A; Arcaro, Michael; Weiner, Kevin S; Kalkus, Jan F; Inati, Souheil J; Gross, Charles G; Kastner, Sabine
Cluster headache is marked by its circadian rhythmicity and the hypothalamus appears to have a significant influence over cluster pathogenesis. However, as not all cluster patients present in the same manner and not all respond to the same combination of medications, there is likely a nonhypothalamic form of cluster headache. A patient is presented who began to develop cluster headaches after receiving bilateral greater occipital nerve (GON) blockade. His headaches fit the IHS criteria for cluster headache but had some irregularities including frequent side shifting of pain, irregular duration and time of onset and the ability of the patient to sit completely still during a headache without any sense of agitation. This article will suggest that some forms of cluster headache are not primarily hypothalamic influenced and that the GON may play a significant role in cluster pathogenesis in some individuals. PMID:16355296
Rozen, Todd D
The occurrence of the lesser occipital nerve (LON) at an anomalous location in the “carefree part” within the posterior triangle has been seldom reported in the literature. We are reporting a rare case of location of the LON in the “carefree part” of the posterior triangle, in a 55-year-old formalin embalmed male cadaver. LON, after emerging from the posterior margin of the sternomastoid muscle (SM), ran obliquely towards the trapezius muscle. Here, it hooked around the unusual separated muscle fasciculus of the trapezius, 7.5 cm below the superior nuchal line. Further, LON gave contributions to spinal accessory nerve (SAN); one deep into the SM and another one in the posterior triangle. The knowledge on the unusual location and course of the LON and its contribution to the SAN is significantly important while an anaesthetic blockade is being performed for the management of a cervicogenic headache and a super selective radical neck dissection.
Sirasanagandla, Srinivasa Rao; Nayak, Satheesha B; Rao KG, Mohandas; Patil, Jyothsna
Purpose In contrast to EEG, which has guidelines for interpretation and a plethora of textbooks, the full range of activity seen in Magnetoencephalography (MEG) has not been fleshed out. Currently, magnetoencephalographers apply criteria for EEG waveforms to MEG signals based on an assumption that MEG activity should have morphology that is similar to EEG. The purpose of this paper is to show the characteristic MEG profile of Positive Occipital Sharp Transients of Sleep (POSTS) Method Simultaneous MEG-EEG recordings of two cases are shown. Result In the both cases, the morphological features of POSTS in MEG vary, and sometimes mimic epileptic spikes. Conclusion This report raises a caution that a normal variant may have an even more epileptic appearance on MEG than on EEG. Employing the simultaneously recorded EEG to avoid misinterpretation of spikey-looking POSTS in MEG is a natural and prudent practice.
Kakisaka, Yosuke; Wang, Zhong I.; Enatsu, Rei; Dubarry, Anne-Sophie; Mosher, John C.; Alexopoulos, Andreas V.; Burgess, Richard C.
Artificial fronto-occipital deformation of the cranial vault was typical of pre-Columbian cultures in the central Andean coastal regions. We have studied the influence of this deformation on maxillary and mandibular morphology. Measurements were performed on 86 adult Ancon skulls with anteroposterior deformation. Undeformed skulls from the area of Makatampu (n = 52) were used as the control group. To explore the influence of the deformity on occlusion, the skulls were categorized using the Angle classification and the alignment of the interincisor midline. In the group of deformed skulls, there was an increase in lateral growth of the vault and of the base of the skull (P < 0.001), giving rise to a greater interpterygoid width of the maxilla (P < 0.001), and an increase in the transverse diameter of the palatal vault. The mandible presented an increase in the length of the rami (P < 0.001) and in the intercondylar width, with no alteration of mandibular length. The deformed skulls had normal (class I) occlusion, with no displacement of the midline. The difference in the asymmetry index between the two groups was not statistically significant. Artificial fronto-occipital deformation of the cranial vault provoked compensatory lateral expansion of the base that was correlated with the transverse development of the maxilla and mandible. Occlusion and sagittal intermaxillary position were not affected by the cranial deformity. These results provide evidence of the integration between the neurocranium and the viscerocranium in craniofacial development, and support the hypothesis of a compensatory effect of function. PMID:21990029
Jimenez, Publio; Martinez-Insua, Arturo; Franco-Vazquez, Jaime; Otero-Cepeda, Xose Luis; Santana, Urbano
In interpersonal communication, the listener can often see as well as hear the speaker. Visual stimuli can subtly change a listener’s auditory perception, as in the McGurk illusion, in which perception of a phoneme’s auditory identity is changed by a concurrent video of a mouth articulating a different phoneme. Studies have yet to link visual influences on the neural representation of language with subjective language perception. Here we show that vision influences the electrophysiological representation of phonemes in human auditory cortex prior to the presentation of the auditory stimulus. We used the McGurk effect to dissociate the subjective perception of phonemes from the auditory stimuli. With this paradigm we demonstrate that neural representations in auditory cortex are more closely correlated with the visual stimuli of mouth articulation, which drive the illusory subjective auditory perception, than the actual auditory stimuli. Additionally, information about visual and auditory stimuli transfer in the caudal–rostral direction along the superior temporal gyrus during phoneme perception as would be expected of visual information flowing from the occipital cortex into the ventral auditory processing stream. These results show that visual stimuli influence the neural representation in auditory cortex early in sensory processing and may override the subjective auditory perceptions normally generated by auditory stimuli. These findings depict a marked influence of vision on the neural processing of audition in tertiary auditory cortex and suggest a mechanistic underpinning for the McGurk effect.
Smith, Elliot; Duede, Scott; Hanrahan, Sara; Davis, Tyler; House, Paul; Greger, Bradley
In interpersonal communication, the listener can often see as well as hear the speaker. Visual stimuli can subtly change a listener's auditory perception, as in the McGurk illusion, in which perception of a phoneme's auditory identity is changed by a concurrent video of a mouth articulating a different phoneme. Studies have yet to link visual influences on the neural representation of language with subjective language perception. Here we show that vision influences the electrophysiological representation of phonemes in human auditory cortex prior to the presentation of the auditory stimulus. We used the McGurk effect to dissociate the subjective perception of phonemes from the auditory stimuli. With this paradigm we demonstrate that neural representations in auditory cortex are more closely correlated with the visual stimuli of mouth articulation, which drive the illusory subjective auditory perception, than the actual auditory stimuli. Additionally, information about visual and auditory stimuli transfer in the caudal-rostral direction along the superior temporal gyrus during phoneme perception as would be expected of visual information flowing from the occipital cortex into the ventral auditory processing stream. These results show that visual stimuli influence the neural representation in auditory cortex early in sensory processing and may override the subjective auditory perceptions normally generated by auditory stimuli. These findings depict a marked influence of vision on the neural processing of audition in tertiary auditory cortex and suggest a mechanistic underpinning for the McGurk effect. PMID:24023823
Smith, Elliot; Duede, Scott; Hanrahan, Sara; Davis, Tyler; House, Paul; Greger, Bradley
This contribution will present a variety of applications of lab-on-a-chip surface enhanced Raman spectroscopy in the field of bioanalytic. Beside the quantification and online monitoring of drugs and pharmaceuticals, determination of enzyme activity and discrimination of bacteria are successfully carried out utilizing LOC-SERS. The online-monitoring of drugs using SERS in a microfluidic device is demonstrated for nicotine. The enzyme activity of thiopurine methyltransferase (TPMT) in lysed red blood cells is determined by SERS in a lab-on-a-chip device. To analyse the activity of TPMT the metabolism of 6-mercaptopurine to 6-methylmercaptopurine is investigated. The discrimination of bacteria on strain level is carried out with different E. coli strains. For the investigations, the bacteria are busted by ultra sonic to achieve a high information output. This sample preparation provides the possibility to detect SERS spectra containing information of the bacterial cell walls as well as of the cytoplasm. This contribution demonstrates the great potential of LOC-SERS in the field of bioanalytics.
März, Anne; Mönch, Bettina; Walter, Angela; Bocklitz, Thomas; Schumacher, Wilm; Rösch, Petra; Kiehntopf, Michael; Popp, Jürgen
DNAi location: Genome>Tour>flyover>Ubiquilin and olfactory receptor cluster The intergenic region is followed by two adjacent ubiquilin genes, which are involved in key cell processes, from replication to \\"programmed\\" death. Ubiquilin 3 is expressed specifically in the testis, where it is believed to help regulate sperm development. These are followed by a cluster of gene locations (LOC) thought to encode olfactory receptors, which receive stimuli in the nose to allow us to detect smells. At 31,110 nucleotides long, the first gene in this cluster, LOC120009, is the longest we will encounter on our journey. Its 11 coding exons are indicated in red, but most of its bulk comes from its yellow introns and 29 blue and purple transposons. However, the majority of olfactory receptors are short. The next four gene locations are more typical of olfactory receptors in having only one or two coding exons. About 60% of our smell receptors are nonfunctional. Presumably, humans have less need for smell in locating food and interacting socially. The mutations that inactivate many receptors vary among people, meaning that there is a DNA basis for the observation that some people can smell better than others! It also suggests that the loss of smelling acuity has occurred very recently in human evolution and is still ongoing.
Investigating the organization of tone representation in the rodent auditory cortex at high resolution, two new studies in this issue find that the arrangement of relative frequency responsiveness is not preserved at a fine-scale cortical level.
Castro, Jason B; Kandler, Karl
Taste is a primary reinforcer. Olfactory–taste and visual–taste association learning takes place in the primate including human orbitofrontal cortex to build representations of flavor. Rapid reversal of this learning can occur using a rule-based learning system that can be reset when an expected taste or flavor reward is not obtained, that is by negative reward prediction error, to which a population of neurons in the orbitofrontal cortex responds. The representation in the orbitofrontal cortex but not the primary taste or olfactory cortex is of the reward value of the visual/olfactory/taste input as shown by devaluation experiments in which food is fed to satiety, and by correlations of the activations with subjective pleasantness ratings in humans. Sensory-specific satiety for taste, olfactory, visual, and oral somatosensory inputs produced by feeding a particular food to satiety is implemented it is proposed by medium-term synaptic adaptation in the orbitofrontal cortex. Cognitive factors, including word-level descriptions, modulate the representation of the reward value of food in the orbitofrontal cortex, and this effect is learned it is proposed by associative modification of top-down synapses onto neurons activated by bottom-up taste and olfactory inputs when both are active in the orbitofrontal cortex. A similar associative synaptic learning process is proposed to be part of the mechanism for the top-down attentional control to the reward value vs. the sensory properties such as intensity of taste and olfactory inputs in the orbitofrontal cortex, as part of a biased activation theory of selective attention.
Rolls, Edmund T.
Functional imaging techniques have demonstrated a relationship between the intensity of tinnitus and the degree of reorganization\\u000a of the primary auditory cortex. Studies in experimental animals and humans have revealed that tinnitus is associated with\\u000a a synchronized hyperactivity in the auditory cortex and proposed that the underlying pathophysiological mechanism is thalamocortical\\u000a dysrhythmia; hence, decreased auditory stimulation results in decreased firing
Dirk Ridder; G. De Mulder; E. Verstraeten; M. Seidman; K. Elisevich; S. Sunaert; S. Kovacs; K. Van der Kelen; P. Van de Heyning; A. Moller
The left ventral occipito-temporal cortex (LvOT) is thought to be essential for the rapid parallel letter processing that is required for skilled reading. Here we investigate whether rapid written word identification in skilled readers can be supported by neural pathways that do not involve LvOT. Hypotheses were derived from a stroke patient who acquired dyslexia following extensive LvOT damage. The patient followed a reading trajectory typical of that associated with pure alexia, re-gaining the ability to read aloud many words with declining performance as the length of words increased. Using functional MRI and dynamic causal modelling (DCM), we found that, when short (three to five letter) familiar words were read successfully, visual inputs to the patient's occipital cortex were connected to left motor and premotor regions via activity in a central part of the left superior temporal sulcus (STS). The patient analysis therefore implied a left hemisphere "reading-without-LvOT" pathway that involved STS. We then investigated whether the same reading-without-LvOT pathway could be identified in 29 skilled readers and whether there was inter-subject variability in the degree to which skilled reading engaged LvOT. We found that functional connectivity in the reading-without-LvOT pathway was strongest in individuals who had the weakest functional connectivity in the LvOT pathway. This observation validates the findings of our patient's case study. Our findings highlight the contribution of a left hemisphere reading pathway that is activated during the rapid identification of short familiar written words, particularly when LvOT is not involved. Preservation and use of this pathway may explain how patients are still able to read short words accurately when LvOT has been damaged. PMID:23017598
Seghier, Mohamed L; Neufeld, Nicholas H; Zeidman, Peter; Leff, Alex P; Mechelli, Andrea; Nagendran, Arjuna; Riddoch, Jane M; Humphreys, Glyn W; Price, Cathy J
Translating sensory information into perceptual decisions is a core challenge faced by the brain. This ability is understood to rely on weighting sensory evidence in order to form mental templates of the critical differences between objects. Learning is shown to optimize these templates for efficient task performance, but the neural mechanisms underlying this improvement remain unknown. Here, we identify the mechanisms that the brain uses to implement templates for perceptual decisions through experience. We trained observers to discriminate visual forms that were randomly perturbed by noise. To characterize the internal stimulus template that observers learn when performing this task, we adopted a classification image approach (e.g., [5-7]) for the analysis of both behavioral and fMRI data. By reverse correlating behavioral and multivoxel pattern responses with noisy stimulus trials, we identified the critical image parts that determine the observers' choice. Observers learned to integrate information across locations and weight the discriminative image parts. Training enhanced shape processing in the lateral occipital area, which was shown to reflect size-invariant representations of informative image parts. Our findings demonstrate that learning optimizes mental templates for perceptual decisions by tuning the representation of informative image parts in higher ventral cortex. PMID:24012311
Kuai, Shu-Guang; Levi, Dennis; Kourtzi, Zoe
Higher visual areas in the occipitotemporal cortex contain discrete regions for face processing, but it remains unclear if V1 is modulated by top-down influences during face discrimination, and if this is widespread throughout V1 or localized to retinotopic regions processing task-relevant facial features. Employing functional magnetic resonance imaging (fMRI), we mapped the cortical representation of two feature locations that modulate higher visual areas during categorical judgements – the eyes and mouth. Subjects were presented with happy and fearful faces, and we measured the fMRI signal of V1 regions processing the eyes and mouth whilst subjects engaged in gender and expression categorization tasks. In a univariate analysis, we used a region-of-interest-based general linear model approach to reveal changes in activation within these regions as a function of task. We then trained a linear pattern classifier to classify facial expression or gender on the basis of V1 data from ‘eye’ and ‘mouth’ regions, and from the remaining non-diagnostic V1 region. Using multivariate techniques, we show that V1 activity discriminates face categories both in local ‘diagnostic’ and widespread ‘non-diagnostic’ cortical subregions. This indicates that V1 might receive the processed outcome of complex facial feature analysis from other cortical (i.e. fusiform face area, occipital face area) or subcortical areas (amygdala).
Petro, Lucy S; Smith, Fraser W; Schyns, Philippe G; Muckli, Lars
Functional reorganization after focal brain injury can lead to altered cerebral metabolism of glucose. Sturge-Weber syndrome (SWS) with unilateral involvement is a clinical model for evaluating the effects of early focal brain injury on brain metabolism and function. In this study, 2-deoxy-2[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET) was used to measure glucose metabolism in cortex and basal ganglia, both ipsilateral and contralateral to the angioma, in 17 children (eight males, nine females; age range 1y 8mo-10y 4mo; mean 5y 7mo [SD 2y 11mo]) with unilateral SWS and epilepsy. The PET findings were compared with those of a control group of 11 age-matched children (four males, seven females; age range 3y-10y 8mo; mean 6y [SD 2y 10mo]) with partial epilepsy but normal magnetic resonance imaging and PET scans. In the SWS group, visual and parietal cortex showed decreased glucose metabolism on the side of the angioma (p=0.001) but increased metabolism on the contralateral side (p=0.002). In particular, glucose metabolism was very high in contralateral visual cortex of childrenwith SWS, showing severe occipital hypometabolism on the side of the angioma. Eight children with visual field defect showed increased metabolism in the contralateral visual cortex (p=0.012). These findings indicate that early, severe unilateral cortical damage in SWS may induce increased glucose metabolism in the contralateral visual cortex, probably reflecting reorganization. PMID:17635199
Batista, Carlos E A; Juhasz, C; Muzik, O; Chugani, D C; Chugani, H T
A "cavity" lesion made by aspiration in the rat occipital cortex induces a parenchymal and a vascular reaction in its vicinity. The first was mainly characterized by cellular necrosis and gliosis, the second by an increase of the vascular network. In vehicle treated rats, a 50% significant increase of the vascular network was observed around the cavity 4 days after the lesion, in comparison to the uninjured contralateral cortex. The effects of a vasoactive substance, suloctidil, on the vascular reaction was studied in the brain cortex. A single oral dose of suloctidil (30 mg/kg; 2 hours before the sacrifice) gave the same effect as the vehicle group. After 8 days of suloctidil oral administration (30 mg/kg; twice daily: 4 days before lesion and 4 days after) a significant increase (123%) of the vascular network was observed around the cavity. The hypothetical ways by which a chronic treatment of suloctidil induces this increase of the neovascularization observed after cortical lesion are discussed. PMID:2464117
De Paermentier, F; Heuschling, P; Knoops, B; Janssens De Varebeke, P; Pauwels, G; Laszlo De Kaszon-Jakabfalva, C; Van den Bosch De Aguilar, P
Visual motion perception is normally mediated by neural processing in the posterior cortex. Focal damage to the Middle Temporal Area (MT), a posterior extrastriate region, induces motion perception impairment. It is unclear, however, how more broadly distributed cortical dysfunction affects this visual behavior and its neural substrates. Schizophrenia manifests itself in a variety of behavioral and perceptual abnormalities that have proved difficult to understand through a dysfunction of any single brain system. One of these perceptual abnormalities involves impaired motion perception. Motion processing provides an opportunity to clarify the roles of multiple cortical networks in both the healthy and schizophrenic brains. Using fMRI, we measured cortical activation while subjects performed two visual motion tasks (direction discrimination and speed discrimination) and one non-motion task (contrast discrimination). Normal controls showed robust cortical activation (BOLD signal changes) in MT during the direction and speed discrimination tasks, documenting primary processing of sensory input in this posterior region. In schizophrenia patients cortical activation was significantly reduced in MT and significantly increased in the inferior convexity of the prefrontal cortex (ICPFC), an area that is normally involved in higher-level cognitive processing. This shift in cortical responses from posterior to prefrontal regions suggests that motion perception in schizophrenia is associated with both deficient sensory processing and compensatory cognitive processing. Further, this result provides evidence that in the context of broadly distributed cortical dysfunction, the usual functional specificity of the cortex becomes modified even across the domains of sensory and cognitive processing.
Chen, Yue; Grossman, Emily D.; Bidwell, L. Cinnamon; Yurgelun-Todd, Deborah; Gruber, Staci A.; Levy, Deborah L.; Nakayama, Ken; Holzman, Philip S.
Reading requires the extraction of letter shapes from a complex background of text, and an impairment in visual shape extraction would cause difficulty in reading. To investigate the neural mechanisms of visual shape extraction in dyslexia, we used functional magnetic resonance imaging (fMRI) to examine brain activation while adults with or without dyslexia responded to the change of an arrow’s direction in a complex, relative to a simple, visual background. In comparison to adults with typical reading ability, adults with dyslexia exhibited opposite patterns of atypical activation: decreased activation in occipital visual areas associated with visual perception, and increased activation in frontal and parietal regions associated with visual attention. These findings indicate that dyslexia involves atypical brain organization for fundamental processes of visual shape extraction even when reading is not involved. Overengagement in higher-order association cortices, required to compensate for underengagment in lower-order visual cortices, may result in competition for top-down attentional resources helpful for fluent reading.
Zhang, Ying; Whitfield-Gabrieli, Susan; Christodoulou, Joanna A.; Gabrieli, John D. E.
Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25-40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function. PMID:24015304
Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A; Zennig, Corinna; Benca, Ruth M; Lutz, Antoine; Davidson, Richard J; Tononi, Giulio
Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25–40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function.
Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A.; Zennig, Corinna; Benca, Ruth M.; Lutz, Antoine; Davidson, Richard J.; Tononi, Giulio
Magnetic resonance imaging (MRI) was performed in 270 patients with various neurologic complaints (1-15 Y) with a 0.5 tesla superconducting imaging system (MRT-50 A, Toshiba Co.) using a field echo sequence (TR/TE: 300 ms/14 ms) and a spine echo sequence (TR/TE: 2,000 ms/100 ms or 2,000 ms/120 ms, and 2,000 ms/30 ms). The slice thickness was 10 mm. Hyperintensity areas on T2-weighted images were noted at the occipital lobe in 33 patients (12.2%). Twenty-seven of them had hyperintensity within the deep white matter, which revealed iso- or hypointensity on T1-weighted images. The diagnosis for the 27 patients included medulloblastoma after multidisciplinary therapy (1), congenital heart disease (1), neurofibromatosis (1), tuberous sclerosis (1), congenital muscular dystrophy (1), congenital myotonic dystrophy (2), febrile convulsion (2), autism (3), epilepsy (9) and unknown causes (6). Because the hyperintensity areas are age-dependent, they may result from delayed myelination in the central nervous system. PMID:1931165
Miyazaki, M; Hashimoto, T
The insular cortex is located in the centre of the cerebral hemisphere, having connections with the primary and secondary somatosensory areas, anterior cingulate cortex, amygdaloid body, prefrontal cortex, superior temporal gyrus, temporal pole, orbitofrontal cortex, frontal and parietal opercula, primary and association auditory cortices, visual association cortex, olfactory bulb, hippocampus, entorhinal cortex, and motor cortex. Accordingly, dense connections exist among
M. Nagai; K. Kishi; S. Kato
Magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) findings in a 4-year-old child with occipital encephalocele, cerebellar vermis hypogenesis, and tectal malformation are presented. The neuroimaging findings are reminiscent of tectocerebellar dysraphism with an occipital encephalocele (TCD-OE). Additionally, elongated, thickened, and horizontally orientated superior cerebellar peduncles, an abnormally deepened interpeduncular fossa, subependymal heterotopia, and focal cortical dysplasia were noted. Color-coded fractional anisotropy (FA) maps revealed an absence of the decussation of the superior cerebellar peduncles. These findings are highly suggestive of Joubert syndrome and related disorders (JSRD). Our report and the review of the published cases suggest that TCD-OE is not a nosological entity, but may represent the structural manifestation of heterogeneous disorders such as the JSRD spectrum. DTI may be very helpful to differentiate between similar midbrain-hindbrain malformations. PMID:21932183
Poretti, A; Singhi, S; Huisman, T A G M; Meoded, A; Jallo, G; Ozturk, A; Boltshauser, E; Tekes, A
For the past decade, a screw-rod construct has been used commonly to stabilize the atlantoaxial joint, but the insertion of the screw through the C1 lateral mass (LM) can cause several complications. We evaluated whether using a higher screw entry point for C1 lateral mass (LM) fixation than in the standard procedure could prevent screw-induced occipital neuralgia. We enrolled 12 consecutive patients who underwent bilateral C1 LM fixation, with the modified screw insertion point at the junction of the C1 posterior arch and the midpoint of the posterior inferior portion of the C1 LM. We measured postoperative clinical and radiological parameters and recorded intraoperative complications, postoperative neurological deficits and the occurrence of occipital neuralgia. Postoperative plain radiographs were used to check for malpositioning of the screw or failure of the construct. Four patients underwent atlantoaxial stabilization for a transverse ligament injury or a C1 or C2 fracture, six patients for os odontoideum, and two patients for C2 metastasis. No patient experienced vertebral artery injury or cerebrospinal fluid leak, and all had minimal blood loss. No patient suffered significant occipital neuralgia, although one patient developed mild, transient unilateral neuralgia. There was also no radiographic evidence of construct failure. Twenty screws were positioned correctly through the intended entry points, but three screws were placed inferiorly (that is, below the arch), and one screw was inserted too medially. When performing C1-C2 fixation using the standard (Harms) construct, surgeons should be aware of the possible development of occipital neuralgia. A higher entry point may prevent this complication; therefore, we recommend that the screw should be inserted into the arch of C1 if it can be accommodated. PMID:23117140
Lee, Sun-Ho; Kim, Eun-Sang; Eoh, Whan
A patient with a dominantly inherited form of Kuf's disease and an associated occipital astrocytoma is presented. This is the first reported case in which the diagnosis of Kufs' disease was made by a cortical biopsy several years before its expected clinical onset. The nosology of this disease, and its clinical, genetic, and histopathological characteristics are discussed. The establishment of an early diagnosis by cortical biopsy and its implications are considered. Images
Brodner, R A; Noh, J M; Fine, E J
Background: The objective of our study was to determine the safety and usefulness of performing surgery via occipital transtentorial approach to treat posterior cranial fossa tumors, which is well known as an approach to the pineal region (Poppen's approach). Methods: Fourteen patients with posterior cranial fossa tumors were successfully treated using occipital transtentorial approach between 2007 and 2012. The lesions included five meningiomas, three astrocytomas, two metastases, two hemangioblastomas, one cavernoma, and one dysgerminoma. Results: Lesions were <3 cm in 12 cases and ?3 cm in two cases. Average Karnofsky Performance Status (KPS) scoring at admission was 88.5. Eleven patients scored ?70 and seven patients <70. Average age was 43.1 years. All patients underwent surgical treatment by the same surgical team. All tumors were completely removed surgically without any injury to the venous complex and the adjoining structures. There was no incidence of mortality or morbidity in all patients, and all functional outcomes were good to excellent postoperatively. Postoperative computed tomography (CT) imaging revealed that none of the patients had suffered brain damage or infarction around the cerebellum, brainstem, or occipital lobe. Conclusions: We found that the use of occipital transtentorial approach is strongly supported by the successful removal of posterior cranial fossa tumors without serious complications. Open microneurosurgery is probably still the most effective therapy in improving survival and KPS in patients with posterior cranial fossa tumors, given that the proper surgical technique is used and complications do not occur. This case study has strongly suggested that this approach is very useful, safe, and accurate for removing the tumors of posterior fossa and evaluating the surrounding anatomy, as well as for determining operative strategy.
Maselli, Giuliano; De Paulis, Danilo; Ricci, Alessandro; Galzio, Renato J.
Recently, using event-related functional MRI (fMRI), we located a bilateral region in the human posterior parietal cortex (retIPS) that topographically represents and updates targets for saccades and pointing movements in eye-centered coordinates. To generate movements, this spatial information must be integrated with the selected effector. We now tested whether the activation in retIPS is dependent on the hand selected. Using 4-T fMRI, we compared the activation produced by movements, using either eyes or the left or right hand, to targets presented either leftward or rightward of central fixation. The majority of the regions activated during saccades were also activated during pointing movements, including occipital, posterior parietal, and premotor cortex. The topographic retIPS region was activated more strongly for saccades than for pointing. The activation associated with pointing was significantly greater when pointing with the unseen hand to targets ipsilateral to the hand. For example, although there was activation in the left retIPS when pointing to targets on the right with the left hand, the activation was significantly greater when using the right hand. The mirror symmetric effect was observed in the right retIPS. Similar hand preferences were observed in a nearby anterior occipital region. This effector specificity is consistent with previous clinical and behavioral studies showing that each hand is more effective in directing movements to targets in ipsilateral visual space. We conclude that not only do these regions code target location, but they also appear to integrate target selection with effector selection. PMID:15356184
Medendorp, W Pieter; Goltz, Herbert C; Crawford, J Douglas; Vilis, Tutis
Lateral occipital cortical areas are involved in the perception of objects, but it is not clear how these areas interact with first tier visual areas. Using synthetic images portraying a simple texture-defined figure and an electrophysiological paradigm that allows us to monitor cortical responses to figure and background regions separately, we found distinct neuronal networks responsible for the processing of each region. The figure region of our displays was tagged with one temporal frequency (3.0 Hz) and the background region with another (3.6 Hz). Spectral analysis was used to separate the responses to the two regions during their simultaneous presentation. Distributed source reconstructions were made by using the minimum norm method, and cortical current density was measured in a set of visual areas defined on retinotopic and functional criteria with the use of functional magnetic resonance imaging. The results of the main experiments, combined with a set of control experiments, indicate that the figure region, but not the background, was routed preferentially to lateral cortex. A separate network extending from first tier through more dorsal areas responded preferentially to the background region. The figure-related responses were mostly invariant with respect to the texture types used to define the figure, did not depend on its spatial location or size, and mostly were unaffected by attentional instructions. Because of the emergent nature of a segmented figure in our displays, feedback from higher cortical areas is a likely candidate for the selection mechanism by which the figure region is routed to lateral occipital cortex.
Appelbaum, L. Gregory; Wade, Alex R.; Vildavski, Vladimir Y.; Pettet, Mark W.; Norcia, Anthony M.
We quantify the variability in diffuse optical tomography (DOT) sensitivity over the cortical surface in eight young adult subjects. We use the 10/5 electroencephalography system as a basis for our whole-head optical high-density probe design. The contrast-to-noise ratio (CNR) is calculated along with the percentage of the cortex that is above a CNR = 0 dB threshold. We also quantify the effect of including vasculature on the forward model and list our assumptions that allow us to estimate light penetration depth in the head. We show that using the 10/5 system for the optical probe design allows for the measurement of 37% of the cortical surface on average, with a mean CNR in the visible region of 5.5 dB. Certain anatomical regions, such as the lateral occipital cortex, had a very high percentage above the CNR threshold, while other regions such as the cingulate cortex were not measurable. Vasculature blocked optical sensitivity over 1% of the cortex. Cortical coverage was positively correlated with intracranial volume and relative cerebrospinal fluid volume, and negatively correlated with relative scalp volume and skull volume. These contributions allow experimenters to understand how anatomical variation in a subject population may impact DOT or functional near-infrared spectroscopy measurements.
Perdue, Katherine L.; Fang, Qianqian; Diamond, Solomon G.
MRI-guided thermal ablation is a relatively new technique utilising heat to ablate both tumours and epileptogenic lesions. Its use against epilepsy offers some patients a new and relatively safe way of reducing or aborting seizures. Most cases of MRI-guided thermal ablation have been performed in patients with isolated lesions. Placement of depth electrodes prior to laser ablation has been rarely performed. We present a case with bilateral independent lesions traversing eloquent cortex, which, after sampling for seizures and successful ablation, retained normal function. The patient is, to date, seizure-free. PMID:24842711
Clarke, Dave F; Tindall, Kristi; Lee, Mark; Patel, Bhairav
BackgroundAlthough there have been various interposed bypass grafts used for cerebral revascularization, the occipital artery has never been used as a graft. Interposed occipital artery bypass graft in an adult case with moyamoya disease after failed indirect revascularization is presented.Case DescriptionThis 34-year-old woman with moyamoya disease, who had suffered from cerebral ischemic symptoms since the age of 6 years, was
Shigekazu Takeuchi; Tetsuo Koike; Ryuichi Tanaka
Novel imaging technologies provide a detailed look at the structure of the tremendously complex and variable human brain. Optimal exploitation of the information stored in the rapidly growing collection of acquired and segmented MRI data calls for robust and reliable descriptions of the individual geometry of the cerebral cortex. A mathematical description and representation of 3-D shape, capable of dealing
Olaf Kuebler; Gabor Szekely; Christian Brechbuehler; Robert Ogniewicz; Thomas F. Budinger; Peter T. Sander
Computational theories propose that attention modulates the topographical landscape of spatial ‘priority’ maps in regions of visual cortex so that the location of an important object is associated with higher activation levels. While single-unit recording studies have demonstrated attention-related increases in the gain of neural responses and changes in the size of spatial receptive fields, the net effect of these modulations on the topography of region-level priority maps has not been investigated. Here, we used fMRI and a multivariate encoding model to reconstruct spatial representations of attended and ignored stimuli using activation patterns across entire visual areas. These reconstructed spatial representations reveal the influence of attention on the amplitude and size of stimulus representations within putative priority maps across the visual hierarchy. Our results suggest that attention increases the amplitude of stimulus representations in these spatial maps, particularly in higher visual areas, but does not substantively change their size.
Sprague, Thomas C.; Serences, John T.
Although the inferior petro-occipital vein has been recently used for vascular access to the cavernous sinus, few detailed descriptions of its anatomy are in the literature. We aimed to investigate the morphology and relationships of this vessel. Twelve latex-injected cadaveric heads (24 sides) were dissected to identify the inferior petro-occipital vein and anatomic details documented. The petro-occipital vein was identified on 83.3% of sides. Generally this vein united the internal carotid venous plexus to the superior jugular bulb. However, on 10% of sides, the anterior part of this vein communicated directly with the cavernous sinus, and on 15%, the posterior vein drained into the inferior petrosal sinus at its termination into the superior jugular bulb. The petro-occipital vein was separated from the overlying inferior petrosal sinus by a thin plate of bone. On 40% of sides, small venous connections were found between these two venous structures. The vein was usually larger if a nondominant transverse sinus was present. The overlying inferior petrosal sinus was smaller in diameter when an underlying inferior petro-occipital vein was present. On 20% of sides, the posterior aspect of the vein communicated with the hypoglossal canal veins. On three sides, diploic veins from the clivus drained into the inferior petro-occipital vein. The inferior petro-occipital vein is present in most humans. This primarily extracranial vessel communicates with intracranial venous sinuses and should be considered an emissary vein. Knowledge of this vessel's exact anatomy may be useful to cranial base surgeons and endovascular specialists. Clin. Anat. 27:698-701, 2014. © 2013 Wiley Periodicals, Inc. PMID:23716071
Tubbs, R Shane; Watanabe, Koichi; Loukas, Marios; Cohen-Gadol, Aaron A
The present study investigated hierarchical lexical semantic structure in oral descriptions of concrete word meanings produced by a subject (ZZ) diagnosed with anomic aphasia due to left occipital lesions. The focus of the analysis was production of a) nouns at different levels of semantic specificity (e.g., “robin”–“bird”–“animal”) and b) words describing sensory or motor experiences (e.g., “blue,” “soft,” “fly”). Results show that in contrast to healthy and aphasic controls, who produced words at all levels of specificity and mainly vision-related sensory information, ZZ produced almost exclusively nouns at the most non-specific levels and words associated with sound and movement.
Martensson, F.; Roll, M.; Lindgren, M.; Apt, P.; Horne, M.
Attention can dramatically enhance behavioral performance based on a visual stimulus, but the degree to which attention modulates activity in early visual cortex is unclear. Whereas single-unit studies of spatial attention in monkeys have repeatedly revealed relatively modest attentional modulations in V1, human functional magnetic resonance imaging studies demonstrate a large attentional enhancement of the blood oxygen level-dependent (BOLD) signal in V1. To explore this discrepancy, we used intracranial electrodes to directly measure the effect of spatial attention on the responses of neurons near the human occipital pole. We found that spatial attention does not robustly modulate stimulus-driven local field potentials in early human visual cortex, but instead produces modest modulations that are consistent with those seen in monkey neurophysiology experiments. This finding suggests that the neuronal activity that underlies visual attention in humans is similar to that found in other primates and that behavioral state may alter the linear relationship between neuronal activity and BOLD. PMID:18045914
Yoshor, Daniel; Ghose, Geoffrey M; Bosking, William H; Sun, Ping; Maunsell, John H R
Electrical brain stimulation can provide important information about the functional organization of the human visual cortex. Here, we report the visual phenomena evoked by a large number (562) of intracerebral electrical stimulations performed at low-intensity with depth electrodes implanted in the occipito-parieto-temporal cortex of 22 epileptic patients. Focal electrical stimulation evoked primarily visual hallucinations with various complexities: simple (spot or blob), intermediary (geometric forms), or complex meaningful shapes (faces); visual illusions and impairments of visual recognition were more rarely observed. With the exception of the most posterior cortical sites, the probability of evoking a visual phenomenon was significantly higher in the right than the left hemisphere. Intermediary and complex hallucinations, illusions, and visual recognition impairments were almost exclusively evoked by stimulation in the right hemisphere. The probability of evoking a visual phenomenon decreased substantially from the occipital pole to the most anterior sites of the temporal lobe, and this decrease was more pronounced in the left hemisphere. The greater sensitivity of the right occipito-parieto-temporal regions to intracerebral electrical stimulation to evoke visual phenomena supports a predominant role of right hemispheric visual areas from perception to recognition of visual forms, regardless of visuospatial and attentional factors. Hum Brain Mapp 35:3360-3371, 2014. © 2013 Wiley Periodicals, Inc. PMID:24733699
Jonas, Jacques; Frismand, Solène; Vignal, Jean-Pierre; Colnat-Coulbois, Sophie; Koessler, Laurent; Vespignani, Hervé; Rossion, Bruno; Maillard, Louis
Repetition suppression (RS) (or functional magnetic resonance imaging adaptation) refers to the reduction in blood oxygen level–dependent signal following repeated presentation of a stimulus. RS is frequently used to investigate the role of face-selective regions in human visual cortex and is commonly thought to be a “localized” effect, reflecting fatigue of a neuronal population representing a given stimulus. In contrast, predictive coding theories characterize RS as a consequence of “top-down” changes in between-region modulation. Differentiating between these accounts is crucial for the correct interpretation of RS effects in the face-processing network. Here, dynamic causal modeling revealed that different mechanisms underlie different forms of RS to faces in occipitotemporal cortex. For both familiar and unfamiliar faces, repetition of identical face images (same size) was associated with changes in “forward” connectivity between the occipital face area (OFA) and the fusiform face area (FFA) (OFA-to-FFA). In contrast, RS across image size was characterized by altered “backward” connectivity (FFA-to-OFA). In addition, evidence was higher for models in which information projected directly into both OFA and FFA, challenging the role of OFA as the input stage of the face-processing network. These findings suggest “size-invariant” RS to faces is a consequence of interactions between regions rather than being a localized effect.
Henson, Richard N.; Rowe, James B.; Stoyanova, Raliza S.; Calder, Andrew J.
The Nhieu Loc - Thi Nghe basin is the most important administrative and business area of Ho Chi Minh City. Due to system complexity of the basin such as the increasing trend of rainfall intensity, (tidal) water level and land subsidence, the simulation of hydrological, hydraulic variables for flooding prediction seems rather not adequate in practical projects. The basin is still highly vulnerable despite of multi-million USD investment for urban drainage improvement projects since the last decade. In this paper, an integrated system analysis in both spatial and temporal aspects based on statistical, GIS and modelling approaches has been conducted in order to: (1) Analyse risks before and after projects, (2) Foresee water-related risk under uncertainties of unfavourable driving factors and (3) Develop a sustainable flood risk management strategy for the basin. The results show that given the framework of risk analysis and adaptive strategy, certain urban developing plans in the basin must be carefully revised and/or checked in order to reduce the highly unexpected loss in the future
Ho, Long-Phi; Chau, Nguyen-Xuan-Quang; Nguyen, Hong-Quan
Merosin-deficient congenital muscular dystrophy (MD) type 1A (MDC1A) is one of the most frequent forms of CMD in Western countries. The classical form, characterized by a total lack of laminin alpha2 chain expression, usually shows severe clinical features; cases with complete laminin alpha2 deficiency and mild phenotype have also been reported, although the mechanisms underlying the lack of genotype-phenotype correlation have not been elucidated. Epilepsy and focal cortical dysplasia-in addition to the classical diffuse white matter abnormalities-have been described in some of these patients associated with cognitive deterioration. We report on a patient with total laminin alpha2 deficiency due to a homozygous stop-codon mutation in the LAMA2 gene, with mild evolution. When 6.9 years old, she developed focal occipital seizures and absence-like status when awake, with probable relation to an extensive bilateral occipital micropolygyria. Soon afterwards she lost ambulation and developed cognitive deterioration. Our case confirms that the clinical spectrum of MDC1A is more heterogeneous than previously thought. PMID:18406646
Vigliano, Piernanda; Dassi, Patrizia; Di Blasi, Claudia; Mora, Marina; Jarre, Laura
In macaques, superior parietal lobule area 5 has been described as occupying an extensive region, which includes the caudal half of the postcentral convexity as well as the medial bank of the intraparietal sulcus. Modern neuroanatomical methods have allowed the identification of various areas within this region. In the present study, we investigated the corticocortical afferent projections of one of these subdivisions, area PE. Our results demonstrate that PE, defined as a single architectonic area that contains a topographic map of the body, forms specific connections with somatic and motor fields. Thus, PE receives major afferents from parietal areas, mainly area 2, PEc, several areas in the medial bank of the intraparietal sulcus, opercular areas PGop/PFop, and the retroinsular area, frontal afferents from the primary motor cortex, the supplementary motor area, and the caudal subdivision of dorsal premotor cortex, as well as afferents from cingulate areas PEci, 23, and 24. The presence and relative strength of these connections depend on the location of injection sites, so that lateral PE receives preferential input from anterior sectors of the medial bank of intraparietal sulcus and from the ventral premotor cortex, whereas medial PE forms denser connections with area PEc and motor fields. In contrast with other posterior parietal areas, there are no projections to PE from occipital or prefrontal cortices. Overall, the sensory and motor afferents to PE are consistent with functions in goal-directed movement but also hint at a wider variety of motor coordination roles. PMID:23575861
Bakola, Sophia; Passarelli, Lauretta; Gamberini, Michela; Fattori, Patrizia; Galletti, Claudio
The neural correlates for retention of visual information in visual short-term memory are considered separate from those of sensory encoding. However, recent findings suggest that sensory areas may play a role also in short-term memory. We investigated the functional relevance, spatial specificity, and temporal characteristics of human early visual cortex in the consolidation of capacity-limited topographic visual memory using transcranial magnetic stimulation (TMS). Topographically specific TMS pulses were delivered over lateralized occipital cortex at 100, 200, or 400 ms into the retention phase of a modified change detection task with low or high memory loads. For the high but not the low memory load, we found decreased memory performance for memory trials in the visual field contralateral, but not ipsilateral to the side of TMS, when pulses were delivered at 200 ms into the retention interval. A behavioral version of the TMS experiment, in which a distractor stimulus (memory mask) replaced the TMS pulses, further corroborated these findings. Our findings suggest that retinotopic visual cortex contributes to the short-term consolidation of topographic visual memory during early stages of the retention of visual information. Further, TMS-induced interference decreased the strength (amplitude) of the memory representation, which most strongly affected the high memory load trials. PMID:22219265
van de Ven, Vincent; Jacobs, Christianne; Sack, Alexander T
Novel stimuli often require a rapid reallocation of sensory processing resources to determine the significance of the event, and the appropriate behavioral response. Both the amygdala and the visual cortex are central elements of the neural circuitry responding to novelty, demonstrating increased activity to new as compared to highly familiarized stimuli. Further, these brain areas are intimately connected, and thus the amygdala may be a key region for directing sensory processing resources to novel events. Although knowledge regarding the neurocircuit of novelty detection is gradually increasing, we still lack a basic understanding of the conditions that are necessary and sufficient for novelty-specific responses in human amygdala and the visual cortices, and if these brain areas interact during detection of novelty. In the present study, we investigated the response of amygdala and the visual cortex to novelty, by comparing functional MRI activity between 1st and 2nd time presentation of a series of emotional faces in an event-related task. We observed a significant decrease in amygdala and visual cortex activity already after a single stimulus exposure. Interestingly, this decrease in responsiveness was less for subjects with a high score on state anxiety. Further, novel faces stimuli were associated with a relative increase in the functional coupling between the amygdala and the inferior occipital gyrus (BA 18). Thus, we suggest that amygdala is involved in fast sensory boosting that may be important for attention reallocation to novel events, and that the strength of this response depends on individual state anxiety.
Ousdal, Olga T.; Andreassen, Ole A.; Server, Andres; Jensen, Jimmy
The ability to use abstract rules or principles allows behavior to generalize from specific circumstances. We have previously shown that such rules are encoded in the lateral prefrontal cortex (PFC) and premotor cortex (PMC). Here, we extend these investigations to two other areas directly connected with the PFC and the PMC, the inferior temporal cortex (ITC) and the dorsal striatum (STR). Monkeys were trained to use two abstract rules: "same" or "different". They had to either hold or release a lever, depending on whether two successively presented pictures were the same or different, and depending on which rule was in effect. The rules and the behavioral responses were reflected most strongly and, on average, tended to be earlier in the PMC followed by the PFC and then the STR; few neurons in the ITC reflected the rules or the actions. By contrast, perceptual information (the identity of the pictures used as sample and test stimuli) was encoded more strongly and earlier in the ITC, followed by the PFC; they had weak, if any, effects on neural activity in the PMC and STR. These findings are discussed in the context of the anatomy and posited functions of these areas. PMID:16839304
Muhammad, Rahmat; Wallis, Jonathan D; Miller, Earl K
The occipital face area (OFA) is face-selective. This enhanced activation to faces could reflect either generic face and shape-related processing or high-level conceptual processing of identity. Here we examined these two possibilities using a state-dependent transcranial magnetic stimulation (TMS) paradigm. The lateral occipital (LO) cortex which is activated non-selectively by various types of objects served as a control site. We localized OFA and LO on a per-participant basis using functional MRI. We then examined whether TMS applied to either of these regions affected the ability of participants to decide whether two successively presented and physically different face images were of the same famous person or different famous people. TMS was applied during the delay between first and second face presentations to investigate whether neuronal populations in these regions played a causal role in mediating the behavioral effects of identity repetition. Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different. Surprisingly, TMS applied over LO (but not OFA) modulated overall RTs, compared to the No-TMS condition. But critically, we found no effects of TMS to either area that were modulated by identity repetition. Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing. Instead, these brain regions may be involved in the processing of more generic features of their preferred stimulus categories.
Gilaie-Dotan, Sharon; Silvanto, Juha; Schwarzkopf, Dietrich S.; Rees, Geraint
Giant plexiform neurofibroma (GPNF) of the scalp is an extremely rare lesion reported in association with neurofibromatosis. Occipital location of GPNF is even more infrequent, especially in association with occipital dysplasia (OD). The authors report 2 pediatric cases of GPNF associated with OD. The first case had an associated meningoencephalocele, and the second had large vascular channels within the lesion and the dominant ipsilateral transverse sinus lying in the center of the calvarial defect. The authors present these 2 unusual cases with a review of literature and discuss the radiological findings, theories of etiopathogenesis of the OD, and management dilemmas. PMID:24032991
Dadlani, Ravi; Sadanand, Venkatraman; Ghosal, Nandita; Hegde, Alangar S
This article describes a large-scale model of turtle visual cortex that simulates the propagating waves of activity seen in real turtle cortex. The cortex model contains 744 multicompartment models of pyramidal cells, stellate cells, and horizontal cells. Input is provided by an array of 201 geniculate neurons modeled as single compartments with spike-generating mechanisms and axons modeled as delay lines.
Zoran Nenadic; Bijoy K. Ghosh; Philip Ulinski
We report two cases of leptomeningeal angiomatosis in atypical frontoparietotemporal locations without an associated facial port-wine stain. Evidence of a leptomeningeal angioma was found in each when they were evaluated for headaches and seizures. The diagnosis of a leptomeningeal angioma was suggested by calcifications noted on computed tomographic scan of the head and confirmed with contrast-enhanced magnetic resonance images of the brain. We hypothesize that given the lack of occipital involvement with the angioma, and therefore the noncontiguous nature of this lesion with the developing upper facial ectoderm, the failure to develop a facial angioma would be expected. We found that the useof an anticonvulsant along with a migraine prophylactic medication appeared to have the greatest efficacy in these two cases, whereas anticonvulsants alone were less helpful. This diagnosis should be considered in any child presenting with seizures or complicated migraines and intracranial calcifications. PMID:12661936
Comi, Anne M; Fischer, Richard; Kossoff, Eric H
While previous results from univariate analysis showed that the activity level of the parahippocampal gyrus (PHG) but not the fusiform gyrus (FG) reflects selective maintenance of the cued picture category, present results from multi-voxel pattern analysis (MVPA) showed that the spatial response patterns of both regions can be used to differentiate the selected picture category in working memory. The ventral temporal and occipital areas including the PHG and FG have been shown to be specialized in perceiving and processing different kinds of visual information, though their role in the representation of visual working memory remains unclear. To test whether the PHG and FG show spatial response patterns that reflect selective maintenance of task-relevant visual working memory in comparison with other posterior association regions, we reanalyzed data from a previous fMRI study of visual working memory with a cue inserted during the delay period of a delayed recognition task. Classification of FG and PHG activation patterns for the selected category (face or scene) during the cue phase was well above chance using classifiers trained with fMRI data from the cue or probe phase. Classification of activity in other temporal and occipital regions for the cued picture category during the cue phase was relatively less consistent even though classification of their activity during the probe recognition was comparable with the FG and PHG. In sum, these findings suggest that the FG and PHG carry information relevant to the cued visual category, and their spatial activation patterns during selective maintenance seem to match those during visual recognition. PMID:23380167
Han, Xufeng; Berg, Alexander C; Oh, Hwamee; Samaras, Dimitris; Leung, Hoi-Chung
Previously, we devised a novel strategy for in vivo 13C MRS using [2-13C]glucose infusion and low-power proton decoupling, and proposed that this strategy could be used to acquire 13C MR spectra from the frontal lobe of the human brain. Here, we demonstrate, for the first time, in vivo 13C MRS of human frontal lobe acquired at 3 T. Because the primary metabolites of [2-13C]glucose can be decoupled using very-low-radiofrequency power, we used a volume coil for proton decoupling in this study. The homogeneous B1 field of the volume coil was found to significantly enhance the decoupling efficiency of the stochastic decoupling sequence. Detailed specific absorption rates inside the human head were analyzed using the finite difference time domain method to ensure experimental safety. In vivo 13C spectra from the occipital and frontal lobes of the human brain were obtained. At a decoupling power of 30 W (time-averaged power, 2.45 W), the spectra from the occipital lobe showed well-resolved spectral resolution and excellent signal-to-noise ratio. Although frontal lobe 13C spectra were affected by local B0 field inhomogeneity, we demonstrated that the spectral quality could be improved using post-acquisition data processing. In particular, we showed that the frontal lobe glutamine C5 at 178.5 ppm and aspartate C4 at 178.3 ppm could be spectrally resolved with effective proton decoupling and B0 field correction. Because of its large spatial coverage, volume coil decoupling provides the potential to acquire 13C MRS from more than one brain region simultaneously.
Li, Shizhe; Zhang, Yan; Wang, Shumin; Araneta, Maria Ferraris; Johnson, Christopher S.; Xiang, Yun; Innis, Robert B.; Shen, Jun
Many features of visual scenes are represented in the visual cortex in the form of maps. The best studied of these are the maps of features such as ocular dominance and orientation in primary visual cortex (V1). The beautifully regular structure of these maps and their dependence on patterns of neural activity have inspired several dieren t computational models. In
Miguel A. Carreira-Perpi; Georey J. Goodhill
The ‘executive’ regions of the prefrontal cortex (PFC) such as the dorsolateral PFC (dlPFC) and its rodent equivalent medial PFC (mPFC) are thought to respond in concert with the ‘limbic’ regions of the PFC such as the orbitofrontal (OFC) cortex to orchestrate behavior that is consistent with context and expected outcome. Both groups of regions have been implicated in behavioral
Bita Moghaddam; Houman Homayoun
Functional areas of mammalian cerebral cortex seem positioned to minimize costs of their interconnections, down to a best-in-a-billion optimality level. The optimization problem here, originating in microcircuit design, is: Given connections among components, what is the physical placement of the components on a surface that minimizes total length of connections? Because of unfeasibility of measuring long-range “wire length” in the cortex, a simpler adjacency cost was validated. To deal with incomplete information on brain networks, a size law was developed that predicts optimization patterns in subnetworks. Macaque and cat cortex rank better in this connection optimization than the wiring of comparably structured computer chips, but somewhat worse than the macroeconomic commodity-flow network among U.S. states. However, cortex wiring conforms to the size law better than the macroeconomic patterns, which may indicate cortex optimizing mechanisms involve more global processes.
Cherniak, Christopher; Mokhtarzada, Zekeria; Rodriguez-Esteban, Raul; Changizi, Kelly
Abstract During closed-loop control of a brain–computer interface, neurons in the primary motor cortex can be intensely active even though the subject may be making no detectable movement or muscle contraction. How can neural activity in the primary motor cortex become dissociated from the movements and muscles of the native limb that it normally controls? Here we examine circumstances in which motor cortex activity is known to dissociate from movement – including mental imagery, visuo-motor dissociation and instructed delay. Many such motor cortex neurons may be related to muscle activity only indirectly. Furthermore, the integration of thousands of synaptic inputs by individual ?-motoneurons means that under certain circumstances even cortico-motoneuronal cells, which make monosynaptic connections to ?-motoneurons, can become dissociated from muscle activity. The natural ability of motor cortex neurons under voluntarily control to become dissociated from bodily movement may underlie the utility of this cortical area for controlling brain–computer interfaces.
Schieber, Marc H
Background There are increasing evidences on the role of non-coding RNA (ncRNA) as key regulator of cellular homeostasis. LOC284889 is an uncharacterized ncRNA gene on reverse strand to MIF mapped to 22q11.23. MIF, a lymphokine, regulates innate immune response by up-regulating the expression of TLR4, suppressing the p53 activity and has been shown to be involved in malaria pathogenesis. Methods In this study, the possible effect of MIF variations on malaria susceptibility was investigated by re-sequencing the complete MIF gene along with 1 kb each of 5? and 3? region in 425 individuals from malaria endemic regions of the Orissa and Chhattisgarh states of India. The subjects comprised of 160 cases of severe malaria, 101 of mild malaria and 164 ethnically matched asymptomatic controls. Data were statistically compared between cases and controls for their possible association with Plasmodium falciparum malarial outcome. Results It is the first study, which shows that the allele A (rs34383331T?>?A) in ncRNA is significantly associated with increased risk to P. falciparum malaria [severe: OR?=?2.08, p?=?0.002 and mild: OR?=?2.09, P?=?0.005]. In addition, it has been observed that the higher MIF-794CATT repeats (>5) increases malaria risk (OR?=?1.61, p?=?0.01). Further, diplotype (MIF-794CATT and rs34383331T?>?A) 5 T confers protection to severe malaria (OR?=?0.55, p?=?0.002) while 6A (OR?=?3.07, p?=?0.001) increases malaria risk. Conclusions These findings support the involvement of ncRNA in malarial pathogenesis and further emphasize the complex genetic regulation of malaria outcome. In addition, the study shows that the higher MIF-794CATT repeats (>5) is a risk factor for severe malaria. The study would help in identifying people who are at higher risk to malaria and adapt strategies for prevention and treatment.
All non-human primates communicate with conspecifics using vocalizations, a system involving both the production and perception of species-specific vocal signals. Much of the work on the neural basis of primate vocal communication in cortex has focused on the sensory processing of vocalizations, while relatively little data are available for vocal production. Earlier physiological studies in squirrel monkeys had shed doubts on the involvement of primate cortex in vocal behaviors. The aim of the present study was to identify areas of common marmoset (Callithrix jacchus) cortex that are potentially involved in vocal communication. In this study, we quantified cFos expression in three areas of marmoset cortex – frontal, temporal (auditory), and medial temporal – under various vocal conditions. Specifically, we examined cFos expression in these cortical areas during the sensory, motor (vocal production), and sensory–motor components of vocal communication. Our results showed an increase in cFos expression in ventrolateral prefrontal cortex as well as the medial and lateral belt areas of auditory cortex in the vocal perception condition. In contrast, subjects in the vocal production condition resulted in increased cFos expression only in dorsal premotor cortex. During the sensory–motor condition (antiphonal calling), subjects exhibited cFos expression in each of the above areas, as well as increased expression in perirhinal cortex. Overall, these results suggest that various cortical areas outside primary auditory cortex are involved in primate vocal communication. These findings pave the way for further physiological studies of the neural basis of primate vocal communication.
Miller, Cory T.; DiMauro, Audrey; Pistorio, Ashley; Hendry, Stewart; Wang, Xiaoqin
Infertility is a major health problem today, affecting about 15% of couples trying to conceive a child. Impaired fertility of the male factor is causative in 20% of infertile couples and contributory in up to another 30%-40%. Based on association studies, an increasing number of gene polymorphisms have been proposed to modulate the efficiency of spermatogenesis. Here, we have investigated the possible association of 9 single-nucleotide polymorphisms (SNP) in 8 different genes-FASLG, JMJDIA, LOC203413, TEX15, BRDT, OR2W3, INSR, and TAS2R38--with male infertility. We analyzed a total of 136 men with idiopathic infertility (60 azoospermic and 76 oligozoospermic) and 161 fertile controls. Our study group included individuals of different ethnic origin: 93 of the infertile men were Macedonians, 32 were Albanians, and 11 were of other origin. The control group was composed of 125 Macedonian and 36 Albanian men. The methodology included multiplex polymerase chain reaction/SNaPshot analyses, followed by capillary electrophoresis on an ABI3130 Genetic Analyzer. Of the 9 SNPs evaluated, 3 are significantly associated (P < .05) with male infertility: SNPs rs5911500 in LOC203413, rs3088232 in BRDT, and rs11204546 in OR2W3. SNP rs5911500 showed the strongest association with infertility among Albanians (P = .0001), whereas rs3088232 was most significantly associated with azoospermia among Macedonians (P = .0082). Moreover, the frequency of co-occurrence of LOC203413 minor T allele with either homozygosity or heterozygosity for the BRDT minor G allele was significantly higher among both azoospermic (6 of 60 [10%]; P = .0057; odds ratio [95% confidence interval], 8.83 [1.73-45.08]) and oligozoospermic (10 of 76 [13.2%]; P = .0002; odds ratio [95% confidence interval], 12.04 [2.57-56.47]) men in comparison with fertile controls (2 of 161 [1.2%]). PMID:22016351
Plaseski, Toso; Noveski, Predrag; Popeska, Zaneta; Efremov, Georgi D; Plaseska-Karanfilska, Dijana
Our brain disambiguates the objects in our cluttered visual world seemingly effortlessly, enabling us to understand their significance and to act appropriately. The role of anteromedial temporal structures in this process, particularly the perirhinal cortex, is highly controversial. In some accounts, the perirhinal cortex is necessary for differentiating between perceptually and semantically confusable objects. Other models claim that the perirhinal cortex neither disambiguates perceptually confusable objects nor plays a unique role in semantic processing. One major hurdle to resolving this central debate is the fact that brain damage in human patients typically encompasses large portions of the anteromedial temporal lobe, such that the identification of individual substructures and precise neuroanatomical locus of the functional impairments has been difficult. We tested these competing accounts in patients with Alzheimer's disease with varying degrees of atrophy in anteromedial structures, including the perirhinal cortex. To assess the functional contribution of each anteromedial temporal region separately, we used a detailed region of interest approach. From each participant, we obtained magnetic resonance imaging scans and behavioural data from a picture naming task that contrasted naming performance with living and non-living things as a way of manipulating perceptual and semantic confusability; living things are more similar to one another than non-living things, which have more distinctive features. We manually traced neuroanatomical regions of interest on native-space cortical surface reconstructions to obtain mean thickness estimates for the lateral and medial perirhinal cortex and entorhinal cortex. Mean cortical thickness in each region of interest, and hippocampal volume, were submitted to regression analyses predicting naming performance. Importantly, atrophy of the medial perirhinal cortex, but not lateral perirhinal cortex, entorhinal cortex or hippocampus, significantly predicted naming performance on living relative to non-living things. These findings indicate that one specific anteromedial temporal lobe region-the medial perirhinal cortex-is necessary for the disambiguation of perceptually and semantically confusable objects. Taken together, these results support a hierarchical account of object processing, whereby the perirhinal cortex at the apex of the ventral object processing system is required to bind properties of not just perceptually, but also semantically confusable objects together, enabling their disambiguation from other similar objects and thus comprehension. Significantly, this model combining a hierarchical object processing architecture with a semantic feature statistic account explains why category-specific semantic impairments for living things are associated with anteromedial temporal lobe damage, and pinpoints the root of this syndrome to perirhinal cortex damage. PMID:23250887
Kivisaari, Sasa L; Tyler, Lorraine K; Monsch, Andreas U; Taylor, Kirsten I
Ball Lightning was seen and described since antiquity and recorded in many places. Ball lightning is usually observed during thunderstorms but large number of ball lightning observations is also reported during fine weather without any connection to thunderstorms or lightning. However, so far no one has managed to generate them in the laboratory. It is photographed very rarely and in many cases the authenticity of them is questionable. It is possible that many different phenomena are grouped together and categorized simply as ball lightning. Indeed, the visual hallucinations associated with simple partial epileptic seizures, during which the patient remains conscious, may also be categorized by a patient unaware of his or her condition as ball lightning observation. Such visual hallucinations may occur as a result of an epileptic seizure in the occipital, temporo-occipital or temporal lobes of the cerebrum [1,2,3]. In some cases the hallucination is perceived as a coloured ball moving horizontally from the periphery to the centre of the vision. The ball may appear to be rotating or spinning. The colour of the ball can be red, yellow, blue or green. Sometimes, the ball may appear to have a solid structure surrounded by a thin glow or in other cases the ball appears to generate spark like phenomena. When the ball is moving towards the centre of the vision it may increase its intensity and when it reaches the centre it can 'explode' illuminating the whole field of vision. During the hallucinations the vision is obscured only in the area occupied by the apparent object. The hallucinations may last for 5 to 30 seconds and rarely up to a minute. Occipital seizures may spread into other regions of the brain giving auditory, olfactory and sensory sensations. These sensations could be buzzing sounds, the smell of burning rubber, pain with thermal perception especially in the arms and the face, and numbness and tingling sensation. In some cases a person may experience only one seizure during lifetime and may not be aware of the reason for the experience. Being of good health otherwise, the person may categorize the experience as a ball lightning encounter. If, as described above, the seizure spread into other regions of the brain the resulting experience may appear as electrical effects (the smell, heat sensation, tingling feeling etc.) of ball lightning. Epileptic seizures are a common and important medical problem, with about one in eleven persons experiencing at least one seizure at some point. Thus some of the ball lightning encounters presented in the literature could very well be associated with the experiences of persons who had an epileptic seizure with visual hallucinations.  Blom, S. et al., Epilepsy, Neurology, Edited by S-M Aquilonius and J. Fagius, Liber, 2000.  Panayiotopoulos, C. P., J. Neorl. Neurosurg. Psychiatry, 66, 536-540, 1999.  Bien et al, Brain,123, 244-253, 2000.
Cooray, G. K.; Cooray, V.
Recent research in cognitive neuroscience using virtual reality, robotic technology and brain imaging has linked self-consciousness to the processing and integration of multisensory bodily signals. This work on bodily self-consciousness has implicated the temporo-parietal, premotor and extrastriate cortex and partly originated in work on neurological patients with different disorders of bodily self-consciousness. One class of such disorders is autoscopic phenomena, which are defined as illusory own-body perceptions, during which patients experience the visual illusory reduplication of their own body in extrapersonal space. Three main forms of autoscopic phenomena have been defined. During autoscopic hallucinations, a second own body is seen without any changes in bodily self-consciousness. During out-of-body experiences, the second own body is seen from an elevated perspective and location associated with disembodiment. During heautoscopy, subjects report strong self-identification with the second own body, often associated with the experience of existing at and perceiving the world from two places at the same time. Although it has been proposed that each autoscopic phenomenon is associated with different impairments of bodily self-consciousness, past research on neurological patients and the development of experimental paradigms for the study of bodily self-consciousness has focused on out-of-body experiences and the association with temporo-parietal cortex. Here, we performed quantitative lesion analysis in the-to date-largest group of patients with autoscopic hallucination and heautoscopy and compared the location of brain damage with those of control patients suffering from complex visual hallucinations. We found that heautoscopy was associated with lesions to the left posterior insula, and that autoscopic hallucinations were associated with damage to the right occipital cortex. Autoscopic hallucination and heautoscopy were further associated with distinct symptoms and deficits. The present data suggest that the autoscopic hallucination is a visuo-somatosensory deficit implicating extrastriate cortex and is, despite the visual hallucination of the own body, not associated with major deficits in bodily self-consciousness. Based on the symptoms and deficits in patients with heautoscopy and the implication of the left posterior insula, we suggest that abnormal bodily self-consciousness during heautoscopy is caused by a breakdown of self-other discrimination regarding affective somatosensory experience due to a disintegration of visuo-somatosensory signals with emotional (and/or interoceptive) bodily signals. These brain mechanisms are distinct from those described for out-of-body experiences. The present data extend previous models of autoscopic phenomena and provide clinical evidence for the importance of emotional and interoceptive signal processing in the posterior insula in relation to bodily self-consciousness. PMID:23423672
Heydrich, Lukas; Blanke, Olaf
Two recent imaging studies have shed new light on information representation in human parahippocampal cortex. Despite their different approaches, the two studies both support the view that this brain region represents space at an elementary level. PMID:21820624
Doeller, Christian F; Kaplan, Raphael
Somatic sensory signals provide a major source of feedback to motor cortex. Changes in somatosensory systems after stroke or injury could profoundly influence brain computer interfaces (BCI) being developed to create new output signals from motor cortex activity patterns. We had the unique opportunity to study the responses of hand/arm area neurons in primary motor cortex to passive joint manipulation in a person with a long-standing brain stem stroke but intact sensory pathways. Neurons responded to passive manipulation of the contralateral shoulder, elbow, or wrist as predicted from prior studies of intact primates. Thus fundamental properties and organization were preserved despite arm/hand paralysis and damage to cortical outputs. The same neurons were engaged by attempted arm actions. These results indicate that intact sensory pathways retain the potential to influence primary motor cortex firing rates years after cortical outputs are interrupted and may contribute to online decoding of motor intentions for BCI applications.
Donoghue, John P.; Hochberg, Leigh R.
Neuronal activity in area MT of the extrastriate visual cortex is correlated with the choices monkeys make on perceptual tasks. New evidence suggests that this correlation is stronger on some tasks than others. PMID:11566118
Britten, K H
A fundamental concept in visual processing is that activity in high-order object-category distinctive regions (e.g., lateral occipital complex, fusiform face area, middle temporal+) is dependent on bottom-up flow of activity in earlier retinotopic areas (V2, V3, V4) whose main input originates from primary visual cortex (V1). Thus, activity in down stream areas should reflect lower-level inputs. Here we qualify this notion reporting case LG, a rare case of developmental object agnosia and prosopagnosia. In this person, V1 was robustly activated by visual stimuli, yet intermediate areas (V2–V4) were strongly deactivated. Despite this intermediate deactivation, activity in down stream visual areas remained robust, showing selectivity for houses and places, while selectivity for faces and objects was impaired. The extent of impairment evident in functional magnetic resonance imaging and electroencephalography activations was somewhat larger in the left hemisphere. This pattern of brain activity, coupled with fairly adequate everyday visual performance is compatible with models emphasizing the role of nonlinear local “amplification” of neuronal inputs in eliciting activity in ventral and dorsal visual pathways as well as perceptual experience in the human brain. Thus, while the proper functioning of intermediate areas appears essential for specialization in the cortex, daily visual behavior and reading are maintained even with deactivated intermediate visual areas.
Gilaie-Dotan, Sharon; Perry, Anat; Bonneh, Yoram; Malach, Rafael
Upon his death in 1955, Albert Einstein’s brain was removed, fixed and photographed from multiple angles. It was then sectioned into 240 blocks, and histological slides were prepared. At the time, a roadmap was drawn that illustrates the location within the brain of each block and its associated slides. Here we describe the external gross neuroanatomy of Einstein’s entire cerebral cortex from 14 recently discovered photographs, most of which were taken from unconventional angles. Two of the photographs reveal sulcal patterns of the medial surfaces of the hemispheres, and another shows the neuroanatomy of the right (exposed) insula. Most of Einstein’s sulci are identified, and sulcal patterns in various parts of the brain are compared with those of 85 human brains that have been described in the literature. To the extent currently possible, unusual features of Einstein’s brain are tentatively interpreted in light of what is known about the evolution of higher cognitive processes in humans. As an aid to future investigators, these (and other) features are correlated with blocks on the roadmap (and therefore histological slides). Einstein’s brain has an extraordinary prefrontal cortex, which may have contributed to the neurological substrates for some of his remarkable cognitive abilities. The primary somatosensory and motor cortices near the regions that typically represent face and tongue are greatly expanded in the left hemisphere. Einstein’s parietal lobes are also unusual and may have provided some of the neurological underpinnings for his visuospatial and mathematical skills, as others have hypothesized. Einstein’s brain has typical frontal and occipital shape asymmetries (petalias) and grossly asymmetrical inferior and superior parietal lobules. Contrary to the literature, Einstein’s brain is not spherical, does not lack parietal opercula and has non-confluent Sylvian and inferior postcentral sulci.
Lepore, Frederick E.; Noe, Adrianne
Freezing of gait (FOG) is an elusive phenomenon that debilitates a large number of Parkinson's disease (PD) patients regardless of stage of disease, medication status, or deep brain stimulation implantation. Sensory feedback cues, especially visual feedback cues, have been shown to alleviate FOG episodes or even prevent episodes from occurring. Here, we examine cortical information flow between occipital, parietal, and motor areas during the pre-movement stage of gait in a PD-with-FOG patient that had a strong positive behavioral response to visual cues, one PD-with-FOG patient without any behavioral response to visual cues, and age-matched healthy controls, before and after training with visual feedback. Results for this case study show differences in cortical information flow between the responding PD-with-FOG patient and the other two subject types, notably, an increased information flow in the beta range. Tentatively suggesting the formation of an alternative cortical sensory-motor pathway during training with visual feedback, these results are proposed as subject for further verification employing larger cohorts of patients. PMID:24409167
Velu, Priya D; Mullen, Tim; Noh, Eunho; Valdivia, Matthew C; Poizner, Howard; Baram, Yoram; de Sa, Virginia R
Occipital nerve stimulation (ONS) has been studied in a few clinical trials for the treatment of chronic migraine (CM) with failure to prove sufficient efficacy. To date, peripheral nerve stimulation for the treatment of primary headache is limited to off-label use only. The authors report their institutional experience in CM therapy with combined ONS and supraorbital nerve stimulation (SONS). Fourteen patients treated with dual ONS and SONS for CM were studied with follow-up ranging from 3 to 60 months. Seventy-one percent achieved successful stimulation as defined by a 50% or greater decrease in pain severity. The mean reduction in headache-related visual analog scale (VAS) score was 3.92 ± 2.4. Half of the patients also had resolution of migraine-associated neurological symptoms and returned to normal functional capacity. The main adverse events included lead migration (42.8%), supraorbital lead allodynia (21.4%), and infection (14.2%) with a resulting high reoperation rate (35.7%). The authors' stimulation efficacy was superior to the combined 33% positive response rates (? 50% pain reduction) in the published studies of ONS for CM. This is likely due to the fact that topographical paresthesia induced by combined ONS and SONS covers the area of migraine pain better than ONS alone. The authors also discuss effective surgical techniques to prevent patient morbidity. PMID:23991822
Hann, Shannon; Sharan, Ashwini
Background: Despite the development of microsurgery and cranial base techniques, the surgical management of Foramen Magnum Meningiomas (FMM) continues to be a technical challenge to neurosurgeons. Controversy concerning the utility of systematic condyle drilling for approaching FMM has been raised. Our aim was to describe the surgical technique, analyze its safety, and the postoperative outcome in 12 consecutive FMM patients. Methods: From 1986 to 2011, 12 patients with FMM underwent operations in the Department of Neurosurgery at Servidores do Estado Hospital and in a private clinic. All patients were operated using a standard suboccipital craniectomy, preserving the occipital condyle, opening of the Foramen Magnum, and ipsilateral removal of the posterior arch of C1. Results: There was no operative mortality, nine patients achieved Glasgow Outcome Scale 4 or 5. Condylar resection was not deemed necessary in any case. Gross total resection was achieved in nine patients. After surgery, four patients developed lower cranial nerve weakness. There was no significant postoperative complication in the remaining patients. The average follow-up is 8.2 years. Conclusion The vast majority of FMM can be safely removed with a retrocondylar lateral suboccipital approach without condylar resection, using meticulous microsurgical techniques.
Lynch, Jose Carlos; Temponi, Vicente; Emmerich, Joao Claudio; Pereira, Celestino Esteves; Goncalves, Mariangela Barbi
The population of neurons in the cat motor cortex which receives monosynaptic input from a specific functional region of the somatic sensory cortex was identified with the techniques of intracellular recording and staining with HRP. Both pyramidal and nonpyramidal cells located in the superficial layers of the pericruciate cortex responded to stimulation of the sensory cortex with short latency, excitatory
L. L. Porter; T. Sakamoto; H. Asanuma
Single-neuron recordings have shown that the posterior parietal cortex (PPC) processes spatial information in many frames of reference, including gaze-centered, head-centered, body-centered, and intermediate coding frames. At the population level, rhythmic neuronal synchronization may provide a mechanism by which PPC could selectively emphasize the task-relevant reference frame in spatial processing. Using magnetoencephalography, we tested this hypothesis by studying the modulations in oscillatory activity in a spatial updating task. Human subjects had to remember the location of a target, briefly flashed left or right of central fixation. Next, they refixated and then, after a further memory delay, made a saccade to the memorized target location. We observed gamma-band (>40 Hz) synchronization and alpha-band (8-12 Hz) desychronization in contralateral occipital and parietal areas, both showing updating in a gaze-centered reference frame but with fast and slow time courses, respectively. Furthermore, after updating, ipsilateral areas showed less alpha desynchronization when they had been contralateral to the target before updating. Taken together, our results suggest that power in the gamma band is instantly reorganized to encode task-relevant visuomotor space in a gaze-centered reference frame, while power in the alpha band reflects a regulatory mechanism actively facilitating the gating of the saccade target and inhibiting the original stimulus representation. PMID:22414770
Van Der Werf, J; Buchholz, V N; Jensen, O; Medendorp, W P
There has been recent interest in the neural correlates of visual short-term memory (VSTM) interference by irrelevant perceptual input. These studies, however, presented distracters that were subjected to conscious scrutiny by participants thus strongly involving attentional control mechanisms. In order to minimize the role of attentional control and to investigate interference occurring at the level of sensory representations, we developed a paradigm in which a subliminal visual distracter is presented during the delay period of a visual short-term memory task requiring the maintenance of stimulus orientation. This subliminal distracter could be either congruent or incongruent with the orientation of the memory item. Behavioral results showed that the intervening distracter affected the fidelity of VSTM when it was incongruent with the memory cue. We then assessed the causal role of the early visual cortex in this interaction by using transcranial magnetic stimulation (TMS). We found that occipital TMS impaired the fidelity VSTM content in the absence of the memory mask. Interestingly, TMS facilitated VSTM performance in the presence of a subliminal memory mask that was incongruent with the memory content. Signal detection analyses indicated that TMS did not modulate perceptual sensitivity of the masked distracter. That the impact of TMS on the precision of VSTM was dissociated by the presence vs. absence of a subliminal perceptual distracter and its congruency with the VSTM content provides causal evidence for the view that competitive interactions between memory and perception can occur at the earliest cortical stages of visual processing. PMID:21839180
Silvanto, Juha; Soto, David
Individuals with developmental prosopagnosia exhibit severe and lasting difficulties in recognizing faces despite the absence of apparent brain abnormalities. We used voxel-based morphometry to investigate whether developmental prosopagnosics show subtle neuroanatomical differences from controls. An analysis based on segmentation of T1-weighted images from 17 developmental prosopagnosics and 18 matched controls revealed that they had reduced grey matter volume in the right anterior inferior temporal lobe and in the superior temporal sulcus/middle temporal gyrus bilaterally. In addition, a voxel-based morphometry analysis based on the segmentation of magnetization transfer parameter maps showed that developmental prosopagnosics also had reduced grey matter volume in the right middle fusiform gyrus and the inferior temporal gyrus. Multiple regression analyses relating three distinct behavioural component scores, derived from a principal component analysis, to grey matter volume revealed an association between a component related to facial identity and grey matter volume in the left superior temporal sulcus/middle temporal gyrus plus the right middle fusiform gyrus/inferior temporal gyrus. Grey matter volume in the lateral occipital cortex was associated with component scores related to object recognition tasks. Our results demonstrate that developmental prosopagnosics have reduced grey matter volume in several regions known to respond selectively to faces and provide new evidence that integrity of these areas relates to face recognition ability.
Furl, Nicholas; Draganski, Bogdan; Weiskopf, Nikolaus; Stevens, John; Tan, Geoffrey Chern-Yee; Driver, Jon; Dolan, Ray J.; Duchaine, Bradley
Imagination is a key function for many human activities, such as reminiscing, learning, or planning. Unravelling its neuro-biological basis is paramount to grasp the essence of our thoughts. Previous neuroimaging studies have identified brain regions subserving the visualisation of "what?" (e.g. faces or objects) and "where?" (e.g. spatial layout) content of mental images. However, the functional role of a common set of involved regions - the frontal regions - and their interplay with the "what" and "where" regions, has remained largely unspecified. This study combines functional MRI and electroencephalography to examine the full-brain network that underlies the visual imagery of complex scenes and to investigate the spectro-temporal properties of its nodes, especially of the frontal cortex. Our results indicate that frontal regions integrate the "what" and "where" content of our thoughts into one visually imagined scene. We link early synchronisation of anterior theta and beta oscillations to regional activation of right and central frontal cortices, reflecting retrieval and integration of information. These frontal regions orchestrate remote occipital-temporal regions (including calcarine sulcus and parahippocampal gyrus) that encode the detailed representations of the objects, and parietal "where" regions that encode the spatial layout into forming one coherent mental picture. Specifically the mesial superior frontal gyrus appears to have a principal integrative role, as its activity during the visualisation of the scene predicts subsequent performance on the imagery task. PMID:22186678
de Borst, Aline W; Sack, Alexander T; Jansma, Bernadette M; Esposito, Fabrizio; de Martino, Federico; Valente, Giancarlo; Roebroeck, Alard; di Salle, Francesco; Goebel, Rainer; Formisano, Elia
Color percept induction in synaesthetes by hearing words was previously shown to involve activation of visual and specifically color processing cortex areas. While this provides a rationale for the origin of the anomalous color percept the question of mechanism of this crossmodal activation remains unclear. We pursued this question with fMRI in color hearing synaesthetes by exposing subjects to words and tones. Brain activations in word condition accompanied by highly reliable color percepts were compared with activations in tone condition with only occasional color percepts and both contrasted to activations in normal subjects under the same stimulus conditions. This revealed that already the tone condition similar to the word condition caused abnormally high activations in various cortical areas even though synaesthetic percepts were more rare. Such tone activations were significantly larger than in normal subjects in visual areas of the right occipital lobe, the fusiform gyrus, and the left middle temporal gyrus and in auditory areas of the left superior temporal gyrus. These auditory areas showed strong word and tone activation alike and not the typically lower tone than word activation in normal subjects. Taken together these results are interpreted in favour of the disinhibited feedback hypothesis as the neurophysiological basis of genuine synaesthesia. PMID:21864461
Gaschler-Markefski, Birgit; Szycik, Gregor R; Sinke, Christopher; Neufeld, Janina; Schneider, Udo; Baumgart, Frank; Dierks, Oliver; Stiegemann, Ursula; Scheich, Henning; Emrich, Hinderk Meiners; Zedler, Markus
The accuracy of forward models for electroencephalography (EEG) partly depends on head tissues geometry and strongly affects the reliability of the source reconstruction process, but it is not yet clear which brain regions are more sensitive to the choice of different model geometry. In this paper we compare different spherical and realistic head modeling techniques in estimating EEG forward solutions from current dipole sources distributed on a standard cortical space reconstructed from Montreal Neurological Institute (MNI) MRI data. Computer simulations are presented for three different four-shell head models, two with realistic geometry, either surface-based (BEM) or volume-based (FDM), and the corresponding sensor-fitted spherical-shaped model. Point Spread Function (PSF) and Lead Field (LF) cross-correlation analyses were performed for 26 symmetric dipole sources to quantitatively assess models' accuracy in EEG source reconstruction. Realistic geometry turns out to be a relevant factor of improvement, particularly important when considering sources placed in the temporal or in the occipital cortex.
Vatta, Federica; Meneghini, Fabio; Esposito, Fabrizio; Mininel, Stefano; Di Salle, Francesco
Although amygdala and frontal lobe functional abnormalities have been reported in patients with mood disorders, the literature regarding Major Depressive Disorder (MDD) is inconsistent. Likely confounds include heterogeneity of patient samples, medication status, and analytic approach. This study evaluated amygdala and frontal lobe activation in unmedicated MDD patients. Fifteen MDD patients and 15 matched healthy controls were scanned using fMRI during the performance of an emotional faces task known to robustly activate the amygdala and prefrontal cortex (PFC). Whole-brain and region of interest analyses were performed, and correlations between clinical features and activation were examined. Significant amygdala and lateral PFC activation were seen within patient and control groups. In a between-group comparison, patients showed significantly reduced activation in the insula, temporal and occipital cortices. In MDD, the presence of anxiety symptoms was associated with decreased orbitofrontal activation. We found robust activation in both the MDD and control groups in fronto-limbic regions with no significant between-group differences using either analytic approach. The current study replicates previous research on unmedicated subjects showing no significant differences in amygdala function in depressed vs. control subjects with respect to simple tasks involving emotion observation.
Townsend, Jennifer D.; Eberhart, Nicole K.; Bookheimer, Susan Y.; Eisenberger, Naomi I.; Foland-Ross, Lara C.; Cook, Ian A.; Sugar, Catherine A.; Altshuler, Lori L.
Emotional stimuli have been shown to preferentially engage initial attention but their sustained effects on neural processing remain largely unknown. The present study evaluated whether emotional faces engage sustained neural processing by examining the attenuation of neural repetition suppression to repeated emotional faces. Repetition suppression of neural function refers to the general reduction of neural activity when processing a repeated stimulus. Preferential processing of emotional face stimuli, however, should elicit sustained neural processing such that repetition suppression to repeated emotional faces is attenuated relative to faces with no emotional content. We measured the reduction of functional magnetic resonance imaging signals associated with immediate repetition of neutral, angry and happy faces. Whereas neutral faces elicited the greatest suppression in ventral visual cortex, followed by angry faces, repetition suppression was the most attenuated for happy faces. Indeed, happy faces showed almost no repetition suppression in part of the right-inferior occipital and fusiform gyri, which play an important role in face-identity processing. Our findings suggest that happy faces are associated with sustained visual encoding of face identity and thereby assist in the formation of more elaborate representations of the faces, congruent with findings in the behavioral literature.
Goh, Joshua O. S.; Hebrank, Andrew; Sutton, Bradley P.; Jenkins, Lucas; Flicker, Blair A.; Park, Denise C.
Fourteen (74%) of 19 patients obtained a significant reduction in seizures after posterior corticectomy; 6 (32%) were seizure-free over a median follow-up of 3.7 years (range, 1 to 14 years). Surgery included limited resections of the occipital lobe in 16 patients, posterior temporal region in 11, and posterior portion of parietal lobe in 7. Surgical failure related to probable multiple areas of epileptogenesis (4 patients), or limited resections (2 patients) to preserve visual fields (2 patients) and to avoid dyslexia (1 patient). Of 14 patients without a complete hemianopia preoperatively, 6 (43%) developed a new or increased visual field deficit, 2 (14%) of which were hemianopia. Four (36%) of 11 occipital lobe resections resulted in a new or increased visual field deficit: quadrantanopia in 3 and hemianopia in 1. Visual phenomena were the most common initial ictal symptoms, occurring in 13 (68%) of the 19 patients. Twelve patients had complex partial seizures: in 2, always without warning; in 7, always following an aura, usually visual; and in 3 patients, with or without warning. Scalp electroencephalography identified the origin of most recorded seizures in 12 (63%) of the 19 patients. A principal interictal spike focus appeared in 15 patients (79%), and always correlated with the epileptogenic lobe as defined by scalp and/or subdural-recorded seizures (14 patients) or by clinical analysis and computed tomography (1 patient). PMID:1892366
Blume, W T; Whiting, S E; Girvin, J P
Schizophrenia is one of the major psychiatric disorders, and lipids have focused on the important roles in this disorder. In fact, lipids related to various functions in the brain. Previous studies have indicated that phospholipids, particularly ones containing polyunsaturated fatty acyl residues, are deficient in postmortem brains from patients with schizophrenia. However, due to the difficulties in handling human postmortem brains, particularly the large size and complex structures of the human brain, there is little agreement regarding the qualitative and quantitative abnormalities of phospholipids in brains from patients with schizophrenia, particularly if corresponding brain regions are not used. In this study, to overcome these problems, we employed matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS), enabling direct microregion analysis of phospholipids in the postmortem brain of a patient with schizophrenia via brain sections prepared on glass slides. With integration of traditional histochemical examination, we could analyze regions of interest in the brain at the micrometric level. We found abnormal phospholipid distributions within internal brain structures, namely, the frontal cortex and occipital cortex. IMS revealed abnormal distributions of phosphatidylcholine molecular species particularly in the cortical layer of frontal cortex region. In addition, the combined use of liquid chromatography/electrospray ionization tandem mass spectrometry strengthened the capability for identification of numerous lipid molecular species. Our results are expected to further elucidate various metabolic processes in the neural system. PMID:21461619
Matsumoto, Junya; Sugiura, Yuki; Yuki, Dai; Hayasaka, Takahiro; Goto-Inoue, Naoko; Zaima, Nobuhiro; Kunii, Yasuto; Wada, Akira; Yang, Qiaohui; Nishiura, Keisuke; Akatsu, Hiroyasu; Hori, Akira; Hashizume, Yoshio; Yamamoto, Takayuki; Ikemoto, Keiko; Setou, Mitsutoshi; Niwa, Shin-ichi
Decision-making impairment has been linked to orbitofrontal cortex lesions and to different disorders including substance abuse, aggression and suicidal behavior. Understanding the neurocognitive mechanisms of these impairments could facilitate the development of effective treatments. In the current study, we aimed to explore the neural and cognitive basis of poor decision-making ability associated with the vulnerability to suicidal behavior, a public health issue in most western countries. Twenty-five not currently depressed male patients, 13 of whom had a history of suicidal acts (suicide attempters) and 12 of whom had none (affective controls), performed an adapted version of the Iowa Gambling Task during functional Magnetic Resonance Imaging. Task-related functional Regions-of-Interest were independently defined in 15 male healthy controls performing the same task (Lawrence et al., 2009). In comparison to affective controls, suicide attempters showed 1) poorer performance on the gambling task 2) decreased activation during risky relative to safe choices in left lateral orbitofrontal and occipital cortices 3) no difference for the contrast between wins and losses. Altered processing of risk under conditions of uncertainty, associated with left lateral orbitofrontal cortex dysfunction, could explain the decision-making deficits observed in suicide attempters. These impaired cognitive and neural processes may represent future predictive markers and therapeutic targets in a field where identification of those at risk is poor and specific treatments are lacking. These results also add to our growing understanding of the role of the orbitofrontal cortex in decision-making and psychopathology. PMID:20302946
Jollant, Fabrice; Lawrence, Natalia S; Olie, Emilie; O'Daly, Owen; Malafosse, Alain; Courtet, Philippe; Phillips, Mary L
Articulatory goals have long been proposed to mediate perception. Examples include direct realist and constructivist (analysis by synthesis) theories of speech perception. Although the activity in brain regions involved with action production has been shown to be present during action observation (Mirror Neuron System), the relationship of this activity to perceptual performance has not been clearly demonstrated at the event level. To this end we used functional magnetic resonance imaging fMRI and magnetoencephalography MEG to measure brain activity for correct and incorrect trials of an auditory phonetic identification in noise task. FMRI analysis revealed activity in the premotor cortex including the neighboring frontal opercular part of Broca's area (PMC/Broca's) for both perception and production tasks involving the same phonetic stimuli (potential mirror system site) that was significantly greater for correct over incorrect perceptual identification trials. Time-frequency analysis of single trials conducted over MEG current localized to PMC/Broca's using a hierarchical variational Bayesian source analysis technique revealed significantly greater event-related synchronization ERS and desynchronization ERD for correct over incorrect trials in the alpha, beta, and gamma frequency range prior to and after stimulus presentation. Together, these fMRI and MEG results are consistent with the hypothesis that articulatory processes serve to facilitate perceptual performance, while further dispelling concerns that activity found in ventral PMC/Broca's (mirror system) is merely a product of covert production of the perceived action. The finding of performance predictive activity prior to stimulus onset as well as activity related to task difficulty instead of information available in stimulation are consistent with constructivist and contrary to direct realist theories of perception. PMID:20184959
Callan, Daniel; Callan, Akiko; Gamez, Mario; Sato, Masa-aki; Kawato, Mitsuo
Objectives To illustrate the clinical presentation, diagnosis, management, and outcome of unilateral right occipital condyle to C2 level spinal cord infarction. Setting A teaching hospital in Taiwan. Findings A 37-year-old man presented with acute-onset severe right neck pain before weakness developed in both right limbs. Early diagnosis was delayed due to mild intervertebral herniation of the C4–C5 disk. Magnetic resonance imaging revealed unilateral right occipital condyle to C2 level infarction. Angiography showed stenosis of the right vertebral artery (foraminal and intradural segments), and dissection of the left vertebral artery at the C1–C2 level. At discharge, he walked with assistance; 2 weeks later, he walked independently. Conclusions An early diagnosis is difficult but important, as it facilitates appropriate treatment for better functional and survival outcomes. Accurate early diagnosis can be made with adequate knowledge of spinal cord infarction and high index of suspicion for this condition.
Wang, Chin-Man; Tsai, Wei-Lun; Lo, Yang-Lan; Chen, Ji-Yih; Wong, Alice M-K
Autism is a severe neurodevelopmental disorder that is characterized by impaired language, communication, and social skills. In regressive autism, affected children first show signs of normal social and language development but eventually lose these skills and develop autistic behavior. Protein kinases are essential in G-protein-coupled, receptor-mediated signal transduction and are involved in neuronal functions, gene expression, memory, and cell differentiation. We studied the activity and expression of protein kinase A (PKA), a cyclic AMP–dependent protein kinase, in postmortem brain tissue samples from the frontal, temporal, parietal, and occipital cortices, and the cerebellum of individuals with regressive autism; autistic subjects without a clinical history of regression; and age-matched developmentally normal control subjects. The activity of PKA and the expression of PKA (C-?), a catalytic subunit of PKA, were significantly decreased in the frontal cortex of individuals with regressive autism compared to control subjects and individuals with non-regressive autism. Such changes were not observed in the cerebellum, or the cortices from the temporal, parietal, and occipital regions of the brain in subjects with regressive autism. In addition, there was no significant difference in PKA activity or expression of PKA (C-?) between non-regressive autism and control groups. These results suggest that regression in autism may be associated, in part, with decreased PKA-mediated phosphorylation of proteins and abnormalities in cellular signaling.
Ji, Lina; Chauhan, Ved; Flory, Michael J.; Chauhan, Abha
What are the neural correlates of attractiveness? Using functional MRI (fMRI), the authors addressed this question in the specific context of the apprehension of faces. When subjects judged facial beauty explicitly, neural activity in a widely distributed network involving the ventral occipital, anterior insular, dorsal posterior parietal, inferior dorsolateral, and medial prefrontal cortices correlated parametrically with the degree of facial attractiveness. When subjects were not attending explicitly to attractiveness, but rather were judging facial identity, the ventral occipital region remained responsive to facial beauty. The authors propose that this region, which includes the fusiform face area (FFA), the lateral occipital cortex (LOC), and medially adjacent regions, is activated automatically by beauty and may serve as a neural trigger for pervasive effects of attractiveness in social interactions. PMID:19254086
Chatterjee, Anjan; Thomas, Amy; Smith, Sabrina E; Aguirre, Geoffrey K
The perirhinal cortex—which is interconnected with several limbic structures and is intimately involved in learning and memory—plays major roles in pathological processes such as the kindling phenomenon of epileptogenesis and the spread of limbic seizures. Both features may be relevant to the pathophysiology of mesial temporal lobe epilepsy that represents the most refractory adult form of epilepsy with up to 30% of patients not achieving adequate seizure control. Compared to other limbic structures such as the hippocampus or the entorhinal cortex, the perirhinal area remains understudied and, in particular, detailed information on its dysfunctional characteristics remains scarce; this lack of information may be due to the fact that the perirhinal cortex is not grossly damaged in mesial temporal lobe epilepsy and in models mimicking this epileptic disorder. However, we have recently identified in pilocarpine-treated epileptic rats the presence of selective losses of interneuron subtypes along with increased synaptic excitability. In this review we: (i) highlight the fundamental electrophysiological properties of perirhinal cortex neurons; (ii) briefly stress the mechanisms underlying epileptiform synchronization in perirhinal cortex networks following epileptogenic pharmacological manipulations; and (iii) focus on the changes in neuronal excitability and cytoarchitecture of the perirhinal cortex occurring in the pilocarpine model of mesial temporal lobe epilepsy. Overall, these data indicate that perirhinal cortex networks are hyperexcitable in an animal model of temporal lobe epilepsy, and that this condition is associated with a selective cellular damage that is characterized by an age-dependent sensitivity of interneurons to precipitating injuries, such as status epilepticus.
Biagini, Giuseppe; D'Antuono, Margherita; Benini, Ruba; de Guzman, Philip; Longo, Daniela; Avoli, Massimo
Near- and far-space coding in the human brain is a dynamic process. Areas in dorsal, as well as ventral visual association cortex, including right posterior parietal cortex (rPPC), right frontal eye field (rFEF), and right ventral occipital cortex (rVO), have been shown to be important in visuospatial processing, but the involvement of these areas when the information is in near or far space remains unclear. There is a need for investigations of these representations to help explain the pathophysiology of hemispatial neglect, and the role of near and far space is crucial to this. We used a conjunction visual search task using an elliptical array to investigate the effects of transcranial magnetic stimulation delivered over rFEF, rPPC, and rVO on the processing of targets in near and far space and at a range of horizontal eccentricities. As in previous studies, we found that rVO was involved in far-space search, and rFEF was involved regardless of the distance to the array. It was found that rPPC was involved in search only in far space, with a neglect-like effect when the target was located in the most eccentric locations. No effects were seen for any site for a feature search task. As the search arrays had higher predictability with respect to target location than is often the case, these data may form a basis for clarifying both the role of PPC in visual search and its contribution to neglect, as well as the importance of near and far space in these. PMID:24259544
Mahayana, Indra T; Liu, Chia-Lun; Chang, Chi Fu; Hung, Daisy L; Tzeng, Ovid J L; Juan, Chi-Hung; Muggleton, Neil G
Burning mouth syndrome (BMS) is a debilitating, idiopathic chronic pain condition. For many BMS patients, burning oral pain begins in late morning and becomes more intense throughout the day, peaking by late afternoon or evening. We investigated brain gray matter volume (GMV) with voxel-based morphometry (VBM), white matter fractional anisotropy (FA) with diffusion tensor imaging (DTI), and functional connectivity in resting state functional MRI (rsfMRI) in a tightly screened, homogeneous sample of 9 female, postmenopausal/perimenopausal BMS patients and 9 matched healthy control subjects. Patients underwent 2 scanning sessions in the same day: in the morning, when ongoing pain/burning was low, and in the afternoon, when pain/burning was significantly higher. Patients had increased GMV and lower FA in the hippocampus (Hc), and decreased GMV in the medial prefrontal cortex (mPFC). rsfMRI revealed altered connectivity patterns in different states of pain/burning, with increased connectivity between mPFC (a node in the default mode network) and anterior cingulate cortex, occipital cortex, ventromedial PFC, and bilateral Hc/amygdala in the afternoon compared with the morning session. Furthermore, mPFC-Hc connectivity was higher in BMS patients than control subjects for the afternoon but not the morning session. mPFC-Hc connectivity was related to Beck depression inventory scores both between groups and between burning states within patients, suggesting that depression and anxiety partially explain pain-related brain dysfunction in BMS. Overall, we provide multiple lines of evidence supporting aberrant structure and function in the mPFC and Hc, and implicate a circuit involving the mPFC and Hc in regulating mood and depressive symptoms in BMS. PMID:24769366
Khan, Shariq A; Keaser, Michael L; Meiller, Timothy F; Seminowicz, David A
Sentence processing problems form a common consequence of left-hemisphere brain injury, in some patients to such an extent that their pattern of language performance is characterized as "agrammatic". However, the location of left-hemisphere damage that causes such problems remains controversial. It has been suggested that the critical site for syntactic processing is Broca's area of the frontal cortex or, alternatively, that a more widely distributed network is responsible for syntactic processing. The aim of this study was to identify brain regions that are required for successful sentence processing. Voxel-based lesion-symptom mapping (VLSM) was used to identify brain regions where injury predicted impaired sentence processing in 50 native speakers of Icelandic with left-hemisphere stroke. Sentence processing was assessed by having individuals identify which picture corresponded to a verbally presented sentence. The VLSM analysis revealed that impaired sentence processing was best predicted by damage to a large left-hemisphere temporo-parieto-occipital area. This is likely due to the multimodal nature of the sentence processing task, which involves auditory and visual analysis, as well as lexical and syntactic processing. Specifically impaired processing of noncanonical sentence types, when compared with canonical sentence processing, was associated with damage to the left-hemisphere anterior superior and middle temporal gyri and the temporal pole. Anterior temporal cortex, therefore, appears to play a crucial role in syntactic processing, and patients with brain damage to this area are more likely to present with receptive agrammatism than patients in which anterior temporal cortex is spared. PMID:22522937
Magnusdottir, S; Fillmore, P; den Ouden, D B; Hjaltason, H; Rorden, C; Kjartansson, O; Bonilha, L; Fridriksson, J
Our working model of the primate auditory cortex recognizes three major regions (core, belt, parabelt), subdivided into thirteen areas. The connections between areas are topographically ordered in a manner consistent with information flow along two major anatomical axes: core-belt-parabelt and caudal-rostral. Remarkably, most of the connections supporting this model were revealed using retrograde tracing techniques. Little is known about laminar circuitry, as anterograde tracing of axon terminations has rarely been used. The purpose of the present study was to examine the laminar projections of three areas of auditory cortex, pursuant to analysis of all areas. The selected areas were: middle lateral belt (ML); caudomedial belt (CM); and caudal parabelt (CPB). Injections of anterograde tracers yielded data consistent with major features of our model, and also new findings that compel modifications. Results supporting the model were: (1) feedforward projection from ML and CM terminated in CPB; (2) feedforward projections from ML and CPB terminated in rostral areas of the belt and parabelt; and (3) feedback projections typified inputs to the core region from belt and parabelt. At odds with the model was the convergence of feedforward inputs into rostral medial belt from ML and CPB. This was unexpected since CPB is at a higher stage of the processing hierarchy, with mainly feedback projections to all other belt areas. Lastly, extending the model, feedforward projections from CM, ML, and CPB overlapped in the temporal parietal occipital area (TPO) in the superior temporal sulcus, indicating significant auditory influence on sensory processing in this region. The combined results refine our working model and highlight the need to complete studies of the laminar inputs to all areas of auditory cortex. Their documentation is essential for developing informed hypotheses about the neurophysiological influences of inputs to each layer and area.
Hackett, Troy A.; de la Mothe, Lisa A.; Camalier, Corrie R.; Falchier, Arnaud; Lakatos, Peter; Kajikawa, Yoshinao; Schroeder, Charles E.
We used fMRI on neurologically intact humans to investigate whether or not there are different neural substrates for the different kinds of information that a visual surface signals (shape from texture vs material properties from texture). Participants attended to differences in the shape (flat/convex), texture and color (wood/rock), or material properties (soft/hard) of a set of circular surfaces. Attending to shape activated the contour-sensitive lateral occipital (LO) area, and attending to texture activated a region of the collateral sulcus (CoS) that overlaps with the parahippocampal place area (PPA). Interestingly, attending to material properties activated the same texture-sensitive region in the CoS. These results demonstrate the existence of different neural substrates for the different types of information that a visual surface signals. With regard to object shape, the organization of the LO area may be complex, with neurons tuned not only to the outline shape of objects, but also to their surface curvature independent of contour. Moreover, to our knowledge, this is the first study to demonstrate that processing surface texture, which occurs within the scene-sensitive PPA, is a route to accessing knowledge about an object's material properties. With this in mind, we propose that models of visual cortical organization should focus not only on the particular stimulus category to which a region maximally responds (e.g., objects, scenes), but also on the stimulus attributes that best support the processing of that category (e.g., shape, texture, material properties). PMID:21632946
Cant, Jonathan S; Goodale, Melvyn A
Secure Surgical Method for Catheter Placement via the Occipital Artery to Achieve Retrograde Superselective Intra-Arterial Chemotherapy for Advanced Oral Cancer: Alternative to Approach via the Superficial Temporal Artery.
We describe secure surgical method for catheter placement using ultrasonic scalpel via the occipital artery to achieve retrograde superselective intra-arterial chemotherapy for advanced oral cancer, as alternative to approach via the superficial temporal artery. PMID:24822164
Iwai, Toshinori; Fuwa, Nobukazu; Hirota, Makoto; Mitsudo, Kenji; Tohnai, Iwai
Nicotinic receptor activation enhances working memory and attention. The prefrontal cortex is a key brain area involved in working memory, and plasticity of excitatory synaptic transmission within the cortex is likely an important cellular mechanism of memory. A recent study has explored the cellular and synaptic basis of nicotine’s effects on excitability within the prefrontal cortex. The findings suggest that nicotine enhances inhibitory synaptic inputs to layer V pyramidal cells, which suppresses induction of long-term potentiation (LTP). This inhibitory effect can be overcome by stimulating the pyramidal cells in bursts, which suggests a modification in the signal-to-noise ratio for synaptic input. Thus, the impact of strong stimuli on working memory would be enhanced when combined with nicotinic receptor activity. These findings may lead to novel and more effective treatments for memory disorders.
Daniel S. McGehee (University of Chicago;Department of Anesthesia and Critical Care REV)
In the visual cortex of the brain, neurons specialized to process particular aspects of the visual input are arranged in complex spatial patterns, called cortical maps, and interact through a dense network of intracortical connections. Many experimental results are consistent with the hypothesis that the precise organization of patterns and connections within the cortex is not predetermined by genetic instructions, but emerges through activity-dependent self-organization during the first months of life. In this chapter, we will first survey the layout of visual cortical maps and the structure of intracortical connections, and then discuss their activity-dependent development. In the subsequent sections of the chapter, we will discuss the formation of patterns in the developing visual cortex from a nonlinear dynamics perspective. In particular, we will analyze the instability mechanisms, through which cortical patterns presumably emerge early in development. We will also discuss the intriguing possibility that cortical patterns undergo substantial rearrangement during the first months of life.
Löwel, Siegrid; Wolf, Fred
Single neurons in monkey parietal cortex update visual information in conjunction with eye movements. This remapping of stimulus representations is thought to contribute to spatial constancy. We hypothesized that a similar process occurs in human parietal cortex and that we could visualize it with functional MRI. We scanned subjects during a task that involved remapping of visual signals across hemifields. We observed an initial response in the hemisphere contralateral to the visual stimulus, followed by a remapped response in the hemisphere ipsilateral to the stimulus. We ruled out the possibility that this remapped response resulted from either eye movements or visual stimuli alone. Our results demonstrate that updating of visual information occurs in human parietal cortex.
Merriam, Elisha P.; Genovese, Christopher R.; Colby, Carol L.
The importance of orbitofrontal cortex (OFC) in human behavioral regulation is no longer a matter of dispute, though its precise role remains a matter of ongoing investigation. It is ironic that this revaluation of OFC required a major departure from a historical nadir, during which it was viewed as redundant or “silent cortex,” a situation that prevailed even up to the latter half of the 20th century. The increasing wealth of data from diverse fields within neuroscience now provides an unambiguous testament to the importance of this cortical region in behavioral regulation and cognition in general.
DOLAN, R. J.
The neural network that contributes to the suffering which accompanies persistent pain states involves a number of brain regions. Of primary interest is the contribution of the cingulate cortex in processing the affective component of pain. The purpose of this review is to summarize recent data obtained using novel behavioral paradigms in animals based on measuring escape and/or avoidance of a noxious stimulus. These paradigms have successfully been used to study the nature of the neuroanatomical and neurochemical contributions of the anterior cingulate cortex (ACC) to higher order pain processing in rodents.
Fuchs, Perry N.; Peng, Yuan Bo; Boyette-Davis, Jessica A.; Uhelski, Megan L.
The cerebellum, parietal cortex, and premotor cortex are integral to visuomotor processing. The parameters of visual information that modulate their role in visuomotor control are less clear. From motor psychophysics, the relation between the frequency of visual feedback and force variability has been identified as nonlinear. Thus we hypothesized that visual feedback frequency will differentially modulate the neural activation in the cerebellum, parietal cortex, and premotor cortex related to visuomotor processing. We used functional magnetic resonance imaging at 3 Tesla to examine visually guided grip force control under frequent and infrequent visual feedback conditions. Control conditions with intermittent visual feedback alone and a control force condition without visual feedback were examined. As expected, force variability was reduced in the frequent compared with the infrequent condition. Three novel findings were identified. First, infrequent (0.4 Hz) visual feedback did not result in visuomotor activation in lateral cerebellum (lobule VI/Crus I), whereas frequent (25 Hz) intermittent visual feedback did. This is in contrast to the anterior intermediate cerebellum (lobule V/VI), which was consistently active across all force conditions compared with rest. Second, confirming previous observations, the parietal and premotor cortices were active during grip force with frequent visual feedback. The novel finding was that the parietal and premotor cortex were also active during grip force with infrequent visual feedback. Third, right inferior parietal lobule, dorsal premotor cortex, and ventral premotor cortex had greater activation in the frequent compared with the infrequent grip force condition. These findings demonstrate that the frequency of visual information reduces motor error and differentially modulates the neural activation related to visuomotor processing in the cerebellum, parietal cortex, and premotor cortex.
Vaillancourt, David E.; Mayka, Mary A.; Corcos, Daniel M.
The orbitofrontal cortex receives multi-modality sensory inputs, including olfactory input, and is thought to be involved in conscious perception of the olfactory image of objects. Generation of olfactory consciousness may require neuronal circuit mechanisms for the “binding” of distributed neuronal activities, with each constituent neuron representing a specific component of an olfactory percept. The shortest neuronal pathway for odor signals to reach the orbitofrontal cortex is olfactory sensory neuron—olfactory bulb—olfactory cortex—orbitofrontal cortex, but other pathways exist, including transthalamic pathways. Here, we review studies on the structural organization and functional properties of the shortest pathway, and propose a model of neuronal circuit mechanisms underlying the temporal bindings of distributed neuronal activities in the olfactory cortex. We describe a hypothesis that suggests functional roles of gamma oscillations in the bindings. This hypothesis proposes that two types of projection neurons in the olfactory bulb, tufted cells and mitral cells, play distinct functional roles in bindings at neuronal circuits in the olfactory cortex: tufted cells provide specificity-projecting circuits which send odor information with early-onset fast gamma synchronization, while mitral cells give rise to dispersedly-projecting feed-forward binding circuits which transmit the response synchronization timing with later-onset slow gamma synchronization. This hypothesis also suggests a sequence of bindings in the olfactory cortex: a small-scale binding by the early-phase fast gamma synchrony of tufted cell inputs followed by a larger-scale binding due to the later-onset slow gamma synchrony of mitral cell inputs. We discuss that behavioral state, including wakefulness and sleep, regulates gamma oscillation couplings across the olfactory bulb, olfactory cortex, and orbitofrontal cortex.
Mori, Kensaku; Manabe, Hiroyuki; Narikiyo, Kimiya; Onisawa, Naomi
Exploiting scene context and object– object co-occurrence is critical in guiding eye movements and facilitating visual search, yet the mediating neural mechanisms are unknown. We used functional magnetic resonance imaging while observers searched for target objects in scenes and used multivariate pattern analyses (MVPA) to show that the lateral occipital complex (LOC) can predict the coarse spatial location of observers’ expectations about the likely location of 213 different targets absent from the scenes. In addition, we found weaker but significant representations of context location in an area related to the orienting of attention (intraparietal sulcus, IPS) as well as a region related to scene processing (retrosplenial cortex, RSC). Importantly, the degree of agreement among 100 independent raters about the likely location to contain a target object in a scene correlated with LOC’s ability to predict the contextual location while weaker but significant effects were found in IPS, RSC, the human motion area, and early visual areas (V1, V3v). When contextual information was made irrelevant to observers’ behavioral task, the MVPA analysis of LOC and the other areas’ activity ceased to predict the location of context. Thus, our findings suggest that the likely locations of targets in scenes are represented in various visual areas with LOC playing a key role in contextual guidance during visual search of objects in real scenes.
Preston, Tim J.; Guo, Fei; Das, Koel; Giesbrecht, Barry; Eckstein, Miguel P.
Docosahexaenoic acid supplementation increases prefrontal cortex activation during sustained attention in healthy boys: a placebo-controlled, dose-ranging, functional magnetic resonance imaging study1234
Background: Emerging evidence suggests that docosahexaenoic acid (DHA, 22:6n?3), the principal omega-3 (n?3) fatty acid in brain gray matter, positively regulates cortical metabolic function and cognitive development. However, the effects of DHA supplementation on functional cortical activity in human subjects are unknown. Objective: The objective was to determine the effects of DHA supplementation on functional cortical activity during sustained attention in human subjects. Design: Healthy boys aged 8–10 y (n = 33) were randomly assigned to receive placebo or 1 of 2 doses of DHA (400 or 1200 mg/d) for 8 wk. Relative changes in cortical activation patterns during sustained attention at baseline and endpoint were determined by functional magnetic resonance imaging. Results: At 8 wk, erythrocyte membrane DHA composition increased significantly from baseline in subjects who received low-dose (by 47%) or high-dose (by 70%) DHA but not in those who received placebo (?11%). During sustained attention, both DHA dose groups had significantly greater changes from baseline in activation of the dorsolateral prefrontal cortex than did the placebo group, and the low-dose and high-dose DHA groups had greater decreases in the occipital cortex and cerebellar cortex, respectively. Relative to low-dose DHA, high-dose DHA resulted in greater decreases in activation of bilateral cerebellum. The erythrocyte DHA composition was positively correlated with dorsolateral prefrontal cortex activation and was inversely correlated with reaction time, at baseline and endpoint. Conclusion: Dietary DHA intake and associated elevations in erythrocyte DHA composition are associated with alterations in functional activity in cortical attention networks during sustained attention in healthy boys. This trial was registered at clinicaltrials.gov as NCT00662142.
Able, Jessica; Jandacek, Ronald; Rider, Therese; Tso, Patrick; Eliassen, James C; Alfieri, David; Weber, Wade; Jarvis, Kelly; DelBello, Melissa P; Strakowski, Stephen M; Adler, Caleb M
A computer program was developed for unfolding the cerebral cortex so that it could be viewed as a 2-dimensional surface. Input to the program consisted of tissue sections cut in a standard plane of section. Each section was represented by one line, which corresponded to a contour line in the flattened map. From these data, the computer constructed a 3-dimensional surface representation, which it then flattened. Because the cerebral cortex has considerable intrinsic curvature, flattening required that some regions be expanded and others shrunken. These changes occurred as a natural consequence of local decisions made by the computer as it laid down successive contours. The user could intervene during both surfacing and flattening in order to shape the developing map. The program has been used to generate 37 flattened maps from various regions of cat cortex, and 1 from monkey cortex. The local topography of cortical features such as gyri, sulci, architectonic boundaries, and patches of transported tracer, appeared to be conserved fairly faithfully. Areal distortion was also modest, with an average change in surface area of only 12%. PMID:1513183
We immunocytochemically identified microglia in fronto-insular (FI) and visual cortex (VC) in autopsy brains of well-phenotyped subjects with autism and matched controls, and stereologically quantified the microglial densities. Densities were determined blind to phenotype using an optical fractionator probe. In FI, individuals with autism had…
Tetreault, Nicole A.; Hakeem, Atiya Y.; Jiang, Sue; Williams, Brian A.; Allman, Elizabeth; Wold, Barbara J.; Allman, John M.
Magnetic source imaging was used to determine whether tonotopy in auditory cortex of individuals with tinnitus diverges from normative functional organization. Ten tinnitus subjects and 15 healthy controls were exposed to four sets of tones while magnetoencephalographic recordings were obtained from the two cortical hemispheres in sequence. A marked shift of the cortical representation of the tinnitus frequency into an
Werner Muhlnickel; Thomas Elbert; Edward Taub; Herta Flor
Although most studies of visual attention have examined the effects of shifting attention between different locations in the visual field, attention can also be directed to particular visual features, such as a color, orientation or a direction of motion. Single-unit studies have shown that attention to a feature modulates neuronal signals in a range of areas in monkey visual cortex.
John H. R. Maunsell; Stefan Treue
Responses were recorded from isolated neurons in the visual cortex of rhesus monkeys while they performed an orientation match to sample task. In each trial the animal was first cued with randomly selected orientation, and then presented with a sequence of gratings whose orientations were randomly selected. The animal was required to release a switch when it saw a grating
P. E. Haenny; J. H. R. Maunsell; P. H. Schiller
The prefrontal cortex (PFC) plays an important role in the integration of cognitive and affective behavior and regulating autonomic and neuroendocrine functions. This region of the brain, which may be considered analogous to the RAM memory of a computer, is important for translating stressful experience into adaptive behavior. The PFC responds to stress and modulates the response to stress through
João J. Cerqueira; Osborne F. X. Almeida; Nuno Sousa
Beginnings Looking back 40 years, it is hard to imagine how the prospects could have been better for us when, in the spring of 1958, we set out to try to understand the visual cortex. We were both medically trained. Torsten had a long experience in psychiatry, he grew up in a mental hospital outside Stockholm and had practiced both
David H. Hubel; Torsten N. Wiesel
We review here a new approach to mapping the human cerebral cortex into distinct subdivisions. Unlike cytoarchitecture or traditional functional imaging, it does not rely on specific anatomical markers or functional hypotheses. Instead, we propose that the unique activity time course (ATC) of each cortical subdivision, elicited during natural conditions, acts as a temporal fingerprint that can be used to
Andreas Bartels; Semir Zeki
Neuroimaging studies of normal subjects and studies of pa- tients with focal lesions implicate regions of parietal cortex in verbal working memory (VWM), yet the precise role of parietal cortex in VWM remains unclear. Some evidence (Paulesu et al., 1993; Awh et al., 1996) suggests that the parietal cortex medi- ates the storage of verbal information, but these studies and
John Jonides; Eric H. Schumacher; Edward E. Smith; Robert A. Koeppe; Edward Awh; Patricia A. Reuter-Lorenz; Christy Marshuetz; Christopher R. Willis
In epilepsy research, there is growing interest in the role of the piriform cortex (PC) in the development and maintenance of limbic kindling and other types of limbic epileptogenesis leading to complex partial seizures, i.e. the most common type of seizures in human epilepsy. The PC (“primary olfactory cortex”) is the largest area of the mammalian olfactory cortex and receives
WOLFGANG LÖSCHER; ULRICH EBERT
In this thesis, we first described a theoretical framework for the analysis of spine remodeling plasticity. We provided a quantitative description of two models of spine remodeling in which the presence of a bouton is either required or not for the formation of a new synapse. We derived expressions for the density of potential synapses in the neuropil, the connectivity fraction, which is the ratio of actual to potential synapses, and the number of structurally different circuits attainable with spine remodeling. We calculated these parameters in mouse occipital cortex, rat CA1, monkey V1, and human temporal cortex. We found that on average a dendritic spine can choose among 4-7 potential targets in rodents and 10-20 potential targets in primates. The neuropil's potential for structural circuit remodeling is highest in rat CA1 (7.1-8.6 bits/mum3) and lowest in monkey V1 (1.3-1.5 bits/mum 3 We next studied the role neuron morphology plays in defining synaptic connectivity. As previously stated it is clear that only pairs of neurons with closely positioned axonal and dendritic branches can be synaptically coupled. For excitatory neurons in the cerebral cortex, ). We also evaluated the lower bound of neuron selectivity in the choice of synaptic partners. Post-synaptic excitatory neurons in rodents make synaptic contacts with more than 21-30% of pre-synaptic axons encountered with new spine growth. Primate neurons appear to be more selective, making synaptic connections with more than 7-15% of encountered axons. We next studied the role neuron morphology plays in defining synaptic connectivity. As previously stated it is clear that only pairs of neurons with closely positioned axonal and dendritic branches can be synaptically coupled. For excitatory neurons in the cerebral cortex, such axo-dendritic oppositions, or potential synapses, must be bridged by dendritic spines to form synaptic connections. To explore the rules by which synaptic connections are formed within the constraints imposed by neuron morphology, we compared the distributions of the numbers of actual and potential synapses between pre- and post-synaptic neurons forming different laminar projections in rat barrel cortex. Quantitative comparison explicitly ruled out the hypothesis that individual synapses between neurons are formed independently of each other. Instead, the data are consistent with a cooperative scheme of synapse formation, where multiple-synaptic connections between neurons are stabilized, while neurons that do not establish a critical number of synapses are not likely to remain synaptically coupled. In the above two projects, analysis of potential synapse numbers played an important role in shaping our understanding of connectivity and structural plasticity. In the third part of this thesis, we shift our attention to the study of the distribution of potential synapse numbers. This distribution is dependent on the details of neuron morphology and it defines synaptic connectivity patterns attainable with spine remodeling. To better understand how the distribution of potential synapse numbers is influenced by the overlap and the shapes of axonal and dendritic arbors, we first analyzed uniform disconnected arbors generated in silico. The resulting distributions are well described by binomial functions. We used a dataset of neurons reconstructed in 3D and generated the potential synapse distributions for neurons of different classes. Quantitative analysis showed that the binomial distribution is a good fit to this data as well. All distributions considered clustered into two categories, inhibitory to inhibitory and excitatory to excitatory projections. We showed that the distributions of potential synapse numbers are universally described by a family of single parameter (p) binomial functions, where p = 0.08, and for the inhibitory and p = 0.19 for the excitatory projections. In the last part of this thesis an attempt is made to incorporate some of the biological constraints we considered thus far, into an artificial neural network model. It became
Fares, Tarec Edmond
The temporo-parieto-occipital (TPO) junction is a complex brain territory heavily involved in several high-level neurological functions, such as language, visuo-spatial recognition, writing, reading, symbol processing, calculation, self-processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three-dimensional subcortical organisation of this highly connected region to minimise post-operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klingler's technique. Proceeding latero-medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo-cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto-occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo-functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post-operative morbidity. PMID:24975421
De Benedictis, Alessandro; Duffau, Hugues; Paradiso, Beatrice; Grandi, Enrico; Balbi, Sergio; Granieri, Enrico; Colarusso, Enzo; Chioffi, Franco; Marras, Carlo Efisio; Sarubbo, Silvio
Temporal arteries are typically below detectable levels of PET scanners, which repeatedly showed to be limiting in finding increased F-FDG accumulation even in histologically proven cases of giant cell arteritis. In 2010, Gaemperli and coworkers showed metabolic active inflammation in temporal arteries in an experimental study using PET with [C]-PK11195 combined with CT angiography. Herein, we present the case where an increased accumulation of routinely used tracer F-FDG can be identified directly in temporal and occipital arteries and even in smaller branches using a common hybrid PET/CT scanner if a brain acquisition protocol is applied. PMID:23510881
Rehák, Zden?k; Szturz, Petr; K?en, Leoš; Fojtík, Zden?k; Staní?ek, Jaroslav
Repair of scalp defects using local hair bearing scalp is technically challenging. Transposition or rotation of local flaps to close the defect has its own disadvantages. Reconstruction of a large posterior scalp defect using occipital artery based pedicled V-Y advancement flap following the excision of a recurrent fibrolipoma of epicranial aponeurosis is reported here. It is possible to reconstruct the defect with hair bearing scalp in a single stage along with primary closure of the donor site using this technique. PMID:22942599
Sharma, Rohit; Sirohi, Deepika; Sinha, Ramen; Menon, P Suresh
How the human auditory system extracts perceptually relevant acoustic features of speech is unknown. To address this question, we used intracranial recordings from nonprimary auditory cortex in the human superior temporal gyrus to determine what acoustic information in speech sounds can be reconstructed from population neural activity. We found that slow and intermediate temporal fluctuations, such as those corresponding to syllable rate, were accurately reconstructed using a linear model based on the auditory spectrogram. However, reconstruction of fast temporal fluctuations, such as syllable onsets and offsets, required a nonlinear sound representation based on temporal modulation energy. Reconstruction accuracy was highest within the range of spectro-temporal fluctuations that have been found to be critical for speech intelligibility. The decoded speech representations allowed readout and identification of individual words directly from brain activity during single trial sound presentations. These findings reveal neural encoding mechanisms of speech acoustic parameters in higher order human auditory cortex.
Pasley, Brian N.; David, Stephen V.; Mesgarani, Nima; Flinker, Adeen; Shamma, Shihab A.; Crone, Nathan E.; Knight, Robert T.; Chang, Edward F.
Psychopathy is a personality disorder characterized by remorseless and impulsive antisocial behavior. Given the significant societal costs of the recidivistic criminal activity associated with the disorder, there is a pressing need for more effective treatment strategies, and hence, a better understanding of the psychobiological mechanisms underlying the disorder. The prefrontal cortex (PFC) is likely to play an important role in psychopathy. In particular, the ventromedial and anterior cingulate sectors of PFC are theorized to mediate a number of social and affective decision-making functions that appear to be disrupted in psychopathy. This article provides a critical summary of human neuroimaging data implicating prefrontal dysfunction in psychopathy. A growing body of evidence associates psychopathy with structural and functional abnormalities in ventromedial PFC and anterior cingulate cortex. Although this burgeoning field still faces a number of methodological challenges and outstanding questions that will need to be resolved by future studies, the research to date has established a link between psychopathy and PFC.
We investigated the key neurodevelopmental factors that determine cortical thickness, namely synaptogenesis and regression, by analyzing the thickness of the visual cortex in humans with early- and late-onset blindness. The bilateral visual cortices of the early blind were significantly thicker than those of the late blind and the sighted controls, but the latter two groups did not differ significantly. This suggests reduced "pruning" of synapses in the visual cortex, which may be due to a lack of visual experience during a critical developmental period. These findings support the hypothesis that sensory experience is necessary for an appropriate regression and remodeling of neuronal processes and that synaptic regression might be a major determinant of macroscopic anatomical features like cortical thickness. PMID:19228973
Jiang, Jiefeng; Zhu, Wanlin; Shi, Feng; Liu, Yong; Li, Jun; Qin, Wen; Li, Kuncheng; Yu, Chunshui; Jiang, Tianzi
Making robust inferences about the functional neuroanatomy of the brain is critically dependent on experimental techniques that examine the consequences of focal loss of brain function. Unfortunately, the use of the most comprehensive such technique-lesion-function mapping-is complicated by the need for time-consuming and subjective manual delineation of the lesions, greatly limiting the practicability of the approach. Here we exploit a recently-described general measure of statistical anomaly, zeta, to devise a fully-automated, high-dimensional algorithm for identifying the parameters of lesions within a brain image given a reference set of normal brain images. We proceed to evaluate such an algorithm in the context of diffusion-weighted imaging of the commonest type of lesion used in neuroanatomical research: ischaemic damage. Summary performance metrics exceed those previously published for diffusion-weighted imaging and approach the current gold standard-manual segmentation-sufficiently closely for fully-automated lesion-mapping studies to become a possibility. We apply the new method to 435 unselected images of patients with ischaemic stroke to derive a probabilistic map of the pattern of damage in lesions involving the occipital lobe, demonstrating the variation of anatomical resolvability of occipital areas so as to guide future lesion-function studies of the region. PMID:23347558
Mah, Yee-Haur; Jager, Rolf; Kennard, Christopher; Husain, Masud; Nachev, Parashkev
Making robust inferences about the functional neuroanatomy of the brain is critically dependent on experimental techniques that examine the consequences of focal loss of brain function. Unfortunately, the use of the most comprehensive such technique—lesion-function mapping—is complicated by the need for time-consuming and subjective manual delineation of the lesions, greatly limiting the practicability of the approach. Here we exploit a recently-described general measure of statistical anomaly, zeta, to devise a fully-automated, high-dimensional algorithm for identifying the parameters of lesions within a brain image given a reference set of normal brain images. We proceed to evaluate such an algorithm in the context of diffusion-weighted imaging of the commonest type of lesion used in neuroanatomical research: ischaemic damage. Summary performance metrics exceed those previously published for diffusion-weighted imaging and approach the current gold standard—manual segmentation—sufficiently closely for fully-automated lesion-mapping studies to become a possibility. We apply the new method to 435 unselected images of patients with ischaemic stroke to derive a probabilistic map of the pattern of damage in lesions involving the occipital lobe, demonstrating the variation of anatomical resolvability of occipital areas so as to guide future lesion-function studies of the region.
Mah, Yee-Haur; Jager, Rolf; Kennard, Christopher; Husain, Masud; Nachev, Parashkev
Quantitative RNA analyses of autopsy materials to diagnose the cause and mechanism of death are challenging tasks in the field of forensic molecular pathology. Alterations in mRNA profiles can be induced by cellular stress responses during supravital reactions as well as by lethal insults at the time of death. Here, we demonstrate that several gene transcripts encoding heat shock proteins (HSPs), a gene family primarily responsible for cellular stress responses, can be differentially expressed in the occipital region of postmortem human cerebral cortices with regard to the cause of death. HSPA2 mRNA levels were higher in subjects who died due to mechanical asphyxiation (ASP), compared with those who died by traumatic injury (TI). By contrast, HSPA7 and A13 gene transcripts were much higher in the TI group than in the ASP and sudden cardiac death (SCD) groups. More importantly, relative abundances between such HSP mRNA species exhibit a stronger correlation to, and thus provide more discriminative information on, the death process than does routine normalization to a housekeeping gene. Therefore, the present study proposes alterations in HSP mRNA composition in the occipital lobe as potential forensic biological markers, which may implicate the cause and process of death.
Chung, Ukhee; Seo, Joong-Seok; Kim, Yu-Hoon; Son, Gi Hoon; Hwang, Juck-Joon
The posterior superior temporal sulcus (pSTS) is active when observing biological motion. We investigated the functional connections of the pSTS node within the action observation network by measuring the after-effect of focal repetitive transcranial magnetic stimulation (rTMS) with whole-brain functional magnetic resonance imaging (fMRI). Participants received 1-Hz rTMS over the pSTS region for 10 min and underwent fMRI immediately after. While scanned, they were shown short video clips of a hand grasping an object (grasp clips) or moving next to it (control clips). rTMS-fMRI was repeated for four consecutive blocks. In two blocks we stimulated the left pSTS region and in the other two the right pSTS region. For each side TMS was applied with an effective intensity (95 % of motor threshold) or with ineffective intensity (50 % of motor threshold). Brain regions showing interactive effects of (clip type) × (TMS intensity) were identified in the lateral temporo-occipital cortex, in the anterior intraparietal region and in the ventral premotor cortex. Remote effects of rTMS were mostly limited to the stimulated hemisphere and consisted in an increase of blood oxygen level-dependent responses to grasp clips compared to control clips. We show that the pSTS occupies a pivotal relay position during observation of goal-directed actions. PMID:22772359
Arfeller, Carola; Schwarzbach, Jens; Ubaldi, Silvia; Ferrari, Paolo; Barchiesi, Guido; Cattaneo, Luigi
Recent in vitro experiments have provided useful insights into the development of connections between the thalamus and the cortex. While most of these previous studies focused on neurite guidance and target recognition, our experiments used a serum-free culture system to examine the possible roles of unidentified diffusible cortex-derived growth factors. We demonstrated that occipital cortical explants release diffusible growth factors that enhance neurite outgrowth from explants of the posterior thalamus (the region around the developing lateral geniculate nucleus). The amount of thalamic outgrowth was dependent on the age of the cocultured cortical slices. Our results suggest that there is an overall increase in the release of cortex-derived growth factors during the first three postnatal weeks in mice; this parallels known postnatal increases in the production of several identified growth factors. We found evidence for two peaks in the release of cortex-derived growth factors during the general upward trend, the first at around postnatal day 6 (shortly after thalamocortical innervation of layer 4) and a second between postnatal days 14 and 18 (just after eye-opening). The increased release of cortex-derived growth factors was not found when cortical slices were from mice that had been dark-reared from birth, suggesting that neural activity may be important for enhancing release. Other regions of the central nervous system, including the cerebellum and medulla, were also capable of stimulating some thalamic outgrowth; neither additional explants of the thalamus nor hepatic explants enhanced outgrowth. Fibroblast growth factor is one substance that is distributed preferentially among those tissues that were stimulatory in our experiments. Its level of transcription is known to increase in the brain during the first three postnatal weeks and to be influenced by neural activity. At low doses, fibroblast growth factor greatly increased outgrowth from isolated posterior thalamic explants. Nerve growth factor, another candidate molecule, was less effective. Overall, our results complement the in vivo observations of others on the synthesis of identified growth factors in the cortex and the factors that influence their production. They suggest that growth factors may influence thalamic neurons, and indicate that fibroblast growth factor, and possibly nerve growth factor, are two candidates for molecules mediating the in vitro effects. PMID:7757266
Lotto, R B; Price, D J
SUMMARY Imaging studies are consistent with the exis- tence of brain regions specialized for color, but electrophysiological studies have produced conflicting results. Here we address the neural basis for color, using targeted single-unit recording in alert macaque monkeys, guided by functional magnetic resonance imaging (fMRI) of the same subjects. Distributed within posterior inferior temporal cortex, a large region encompassing V4,
Bevil R. Conway; Sebastian Moeller; Doris Y. Tsao