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Advancements in fMRI Methods: What Can They Inform about the Functional Organization of the Human Ventral Stream?
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fMRI adaptation: a tool for studying visual representations in the primate brain.
No full textx.1 Adaptation and short-term brain plasticity in high-level object areas. One of the most fundamental properties of the brain that clearly distinguishes it from artificially constructed computational devices is its ability to continuously update its functional properties based on prior experience. This property, also termed brain "plasticity" is manifested on many levels of organization and at many time scales. In recent years, clear demonstrations of experience-dependent modifications of brain activity in the human visual cortex have been established. Fairly long term changes (on the order of days) were observed after subjects learned to recognize unfamiliar shapes (Gauthier et al., 1999), or when trained to recognize subliminally-presented visual objects (Grill-Spector et al., 2000) and even single presentations of objects (van Turennout et al., 2000). Experience-dependent changes are not only evident on long range time scales lasting days, but also in short times scales in the order of seconds. A particularly robust phenomenon is repetition-suppression, or adaptation, in which repeated presentation of the same visual stimulus leads to a consistent and gradual reduction in activation within seconds of the occurrence of the first image presentation. Thi
TemporalChannels
No full textData from Stigliani et al. (2017) used to model temporal channels in visual corte
Training a deep convolutional neural network with multiple face sizes and positions, but not resolutions, is necessary for generating invariant face recognition across these transformations
No full textAn encoding model of temporal processing in human visual cortex
No full textABSTRACTHow is temporal information processed in human visual cortex? There is intense debate as to how sustained and transient temporal channels contribute to visual processing beyond V1. Using fMRI, we measured cortical responses to time-varying stimuli, then implemented a novel 2 temporal-channel encoding model to estimate the contributions of each channel. The model predicts cortical responses to time-varying stimuli from milliseconds to seconds and reveals that (i) lateral occipito-temporal regions and peripheral early visual cortex are dominated by transient responses, and (ii) ventral occipito-temporal regions and central early visual cortex are not only driven by both channels, but that transient responses exceed the sustained. These findings resolve an outstanding debate and elucidate temporal processing in human visual cortex. Importantly, this approach has vast implications because it can be applied with fMRI to decipher neural computations in millisecond resolution in any part of the brain.</jats:p
A preference for mathematical processing outweighs the selectivity for Arabic numbers in the inferior temporal gyrus
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