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Here we test our conceptual understanding of V1 function by asking two experimental questions: 1) How do neurons respond to the spatiotemporal structure contained in dynamic, natural scenes? and 2) What is the true range of visual responsiveness and predictability of neural responses obtained in an unbiased sample of neurons across all layers of cortex? We address these questions by recording responses to natural movie stimuli with 32 channel silicon probes. By simultaneously recording from cells in all layers, and taking all recorded cells, we reduce recording bias that results from hunting for neural responses evoked from drifting bars and gratings. A nonparametric model reveals that many cells that are visually responsive do not appear to be captured by standard receptive field models. Using nonlinear Radial Basis Function kernels in a support vector machine, we can explain the responses of some of these cells better than standard linear and phase-invariant complex cell models. This suggests that V1 neurons exhibit more complex and diverse responses than standard models can capture, ranging from simple and complex cells strongly driven by their classical receptive fields, to cells with more nonlinear receptive fields inferred from the nonparametric and RFB model, and cells that are not visually responsive despite robust firing.
Orientation selectivity is the most striking feature of simple cell coding in V1 which has been shown to emerge from the reduction of higher-order correlations in natural images in a large variety of statistical image models. The most parsimonious on
Response variability, as measured by fluctuating responses upon repeated performance of trials, is a major component of neural responses, and its characterization is key to interpret high dimensional population recordings. Response variability and co
It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. W
When presented with information of any type, from music to language to mathematics, the human mind subconsciously arranges it into a network. A network puts pieces of information like musical notes, syllables or mathematical concepts into context by
Astrocytes affect neural transmission by a tight control via glutamate transporters on glutamate concentrations in direct vicinity to the synaptic cleft and by extracellular glutamate. Their relevance for information representation has been supported