Stimulus-induced decorrelation of neuronal activity in the visual system

The reliability of neuronal encoding of sensory inputs depends on the correlation structure and basic response statistics of the activity of the neurons. We examined the response statistics, including the correlation structures of responses to visual stimuli in the anterior superior temporal sulcus and inferotemporal cortex of the macaque monkey. We find that stimulus-elicited activity starts with a brief period showing reduced response variability and decorrelation of neuronal activity in both time and space. After -50 ms of decorrelated activity, the levels of correlation between and within neuronal responses during periods of stimulus-elicited activity resemble the levels observed in the resting state. The decorrelation and reduction in response variability occurs in both active and inactive neurons, suggesting a network-wide effect. These results suggest that the feedforward components of the network convey signals that are independent of each other. The re-emergence of the correlated activity may reflect signals useful for learning as well as representing the impact of prior expectations about upcoming stimuli