ATTENTION-INDUCED NEURONAL-ACTIVITY IN THE MONKEY SOMATOSENSORY CORTEX REVEALED BY PUPILLOMETRICS

Detection of a sensory stimulus is facilitated when attention is direc ted towards the stimulus source. Neuronal substrates for this psycholo gical effect were studied in monkeys performing an attention-demanding task, by simultaneous recording of neuronal activity and pupillary di lation as an indicator of attentive state. We found that neurons in th e postcentral somatosensory cortex (SI) starred to discharge concurren t with the pupil dilation onset which occurred well before the somatos ensory stimulus. Neuronal firing rates were positively correlated with the degree of dilation, suggesting that the SI neural activity is und er the direct influence of the attentional process.