Spatial Attention Decorrelates Intrinsic Activity Fluctuations in Macaque Area V4

• DOI: 10.1016/j.neuron.2009.09.013
• Publication Date: 2009-09-24T12:46:47Z
• Authors: Jude F. Mitchell; Kristy A. Sundberg; John H. Reynolds
• Keywords: Neurons; 0301 basic medicine; SYSBIO; Time Factors; Neuroscience(all); Statistics as Topic; Action Potentials; Neuropsychological Tests; 03 medical and health sciences; SIGNALING; Space Perception; Reaction Time; Animals; Macaca; Attention; Visual Pathways; Visual Fields; SYSNEURO; Photic Stimulation; Visual Cortex

Attention typically amplifies neuronal responses evoked by task-relevant stimuli while attenuating responses to task-irrelevant distracters. In this context, visual distracters constitute an external source of noise that is diminished to improve attended signal quality. Activity that is internal to the cortex itself, stimulus-independent ongoing correlated fluctuations in firing, might also act as task-irrelevant noise. To examine this, we recorded from area V4 of macaques performing an attention-demanding task. The firing of neurons to identically repeated stimuli was highly variable. Much of this variability originates from ongoing low-frequency (<5 Hz) fluctuations in rate correlated across the neuronal population. When attention is directed to a stimulus inside a neuron's receptive field, these correlated fluctuations in rate are reduced. This attention-dependent reduction of ongoing cortical activity improves the signal-to-noise ratio of pooled neural signals substantially more than attention-dependent increases in firing rate.