Cite as:
Benucci A, Frazor R A, Carandini M, 2007, "Dynamics of population activity in cat primary visual cortex" Perception 36 ECVP Abstract Supplement

Dynamics of population activity in cat primary visual cortex

A Benucci, R A Frazor, M Carandini

An oriented stimulus causes activity in a population of neurons in primary visual cortex (V1). A sudden shift in orientation changes this population activity. Understanding the dynamics of this change can shed light on the underlying computations. We measured population activity with voltage-sensitive dye imaging in area V1 of anesthetized, paralyzed cats (Grinvald and Hildesheim, 2004 Nature Reviews Neuroscience 5 874 - 885). Stimuli were sequences of flashed gratings of random orientation (Ringach et al, 1997 Nature 387 281 - 284). Population activity could be explained (correlation r=0.997±0.002) by a simple linear model, ie by convolving the stimulus with an elemental response, the average response to a single orientation. The linear model, however, underestimated (by tens of milliseconds) the duration of the response when a stimulus was followed by a blank screen. We conclude that the dynamics of population responses to changes in orientation reflect a simple linear computation. However, the brief maintenance of cortical activity can only be explained by a nonlinear mechanism. This maintenance may underlie perceptual phenomena of visual persistence.

[Supported by the National Eye Institute and by the McKnight Endowment Fund for Neuroscience.]

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