Differences in the neuronal correlation between the central and peripheral vision in the cat early visual cortex.

Significant surround modulation was reported in the cortical areas corresponding to the periphery of the visual field, whereas no clear surround modulation was reported in the center. To understand the neural bases underlying the differences of the functions between the cortical areas corresponding to the center and periphery of the visual field, responses of the cells in the cat early visual cortex with their receptive fields in the center and periphery of the visual field were recorded by using multichannel electrodes, and cross-correlations of the spikes in the responses to the full-field stimuli, and the center-surround stimuli, which contained a grating in a central patch and a surround grating, were analyzed. Percentages of the cell pairs showing significant cross-correlation were larger in the cortical areas corresponding to the periphery than the center. In the center of the visual field, the percentages of the cell pairs showing significant cross-correlation significantly decreased as the separation of the recording points increased, and the time lags of the peaks of the cross-correlogram distributed around zero. In the periphery of the visual field, the time lags of the peaks of the cross-correlogram distributed more widely and increased as the separation of the recording points increased. In the responses to the center-surround stimuli in the preferred orientation of each cell, percentages of the cell pairs showing significant cross-correlation were larger in the periphery than the center. These results suggest that more lateral interactions occur in the cortical areas corresponding to the periphery than the center of the visual field.

Correlations between features of event-related potentials and Autism Spectrum Quotient scores.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder and is characterized by deficits in social communication and social interaction. ASD includes a continuum from mild to severe expression of autistic traits. The purpose of the present study was to investigate correlations between event-related potentials (ERPs) during visual-auditory priming, and Autism Spectrum Quotient (AQ) scores, which include subscores in 5 different areas: social skills, attention switching, attention to detail, communication, and imagination. High-density electroencephalograms were recorded while participants performed a visual-auditory priming task that required categorization of auditory stimuli presented following a semantically congruent or incongruent visual primer. Differences in ERPs to auditory targets following semantically congruent and incongruent primers occurred between 200 ms and 600 ms at the posterior temporal electrodes. Amplitudes associated with incongruent auditory stimuli at P7 were negatively correlated with overall AQ scores, and positively correlated with communication subscores. Amplitudes associated with congruent stimuli were positively correlated with attention to detail subscores. In addition, PO7 amplitudes were negatively correlated with communication subscores. The results demonstrate significant correlations between electrophysiological features of cross-modal priming and AQ scores. Our findings suggest that electrophysiological parameters may be useful tools to evaluate the severity of autistic trait expression.

Long-term Object Discrimination at Several Viewpoints Develops Neural Substrates of View-invariant Object Recognition in Inferotemporal Cortex.

Object recognition requires differentiation across different objects and generalization across views of the same object. We previously demonstrated that discrimination of object images at several views without any possibility of association was enough to achieve object recognition within a certain range of viewing angles and confirmed the response tolerance of monkey inferotemporal cells within a similar range of viewing angles. However, neither behavioral object recognition nor electrophysiological response tolerance was complete across views. In the present study, we extended such learning past performance saturation and recorded neuronal activity during the further learning period. When monkeys were trained to discriminate objects at several views, we found that they could discriminate the trained objects regardless of the eventual change in viewing angle, and confirmed a response tolerance at the population level over a large viewing angle range covering all the viewpoints experienced. At the cell population level, such overtraining leads to significantly higher neural response similarity for views of the same objects than for views of different objects regardless of the extent of viewing angle separation. These results suggest a possible method of view-invariant object recognition development.