Attention to Tactile Stimuli Increases Neural Synchrony in Somatosensory Cortex

Perception of tactile stimuli requires that the neural activities evoked by stimuli that are relevant for behavior are efficiently selected. Attention influences the firing rates of neurons in the brainstem, thalamus, and cortex. At the level of secondary somatosensory cortex (SII), the firing rates of about 90% of all neurons are modulated by selective attention. In addition to modulating the firing rates of neurons, selective attention also affects the temporal synchrony of firing between neurons. In tasks in which macaques switched their attention toward and away from tactile and visual stimuli, more than 40% of the neurons in SII cortex changed the degree of synchronous firing between neurons when attending to the tactile stimuli. The effects cannot be accounted for by simple changes in firing rate. Computational models show that changes in synchrony between neurons representing a stimulus is a potential mechanism of selective attention.