Spatial Attention Decorrelates Intrinsic Activity Fluctuations in Macaque Area V4

Neuron. 2009 Sep 24;63(6):879-88. doi: 10.1016/j.neuron.2009.09.013.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Attention / physiology*
  • Macaca / physiology*
  • Neurons / physiology*
  • Neuropsychological Tests
  • Photic Stimulation / methods
  • Reaction Time
  • Space Perception / physiology*
  • Statistics as Topic
  • Time Factors
  • Visual Cortex / cytology*
  • Visual Cortex / physiology
  • Visual Fields
  • Visual Pathways