Neurobiology Invited Seminar Series

John Maunsell is visiting from University of Chicago to give his talk "Reading out neuronal signals from primary visual cortex". Abstract: Much has been learned lot about how sensory, motor and cognitive information is represented in different parts of cerebral cortex. However, we know relatively little about how signals in various cortical representations are selectively accessed by other brain regions to guide behavior. Electrical microstimulation has shown that the activity of specific neurons is linked with specific percepts, and that some patterns of strong cortical activity have no impact on behavior. Optogenetic methods make it possible to explore the readout of cortical activity with greater precision. We have been using optogenetic perturbations to explore the readout of spiking activity in V1 of trained, behaving mice. Using optogenetic excitation or inhibition that is sustained, transient or delivered in white-noise sequences, we have found that mice integrate spikes in V1 nearly perfectly over periods of hundreds of millisecond when detecting near-threshold visual stimuli, and are insensitive to large, rapid increments or decrements in spiking except to the extent that they affect integrated spike counts.