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Attention modulates synchronized neuronal firing in primate somatosensory cortex


A potentially powerful information processing strategy in the brain is to take advantage of the temporal structure of neuronal spike trains. An increase in synchrony within the neural representation of an object or location increases the efficacy of that neural representation at the next synaptic stage in the brain; thus, increasing synchrony is a candidate for the neural correlate of attentional selection1. We investigated the synchronous firing of pairs of neurons in the secondary somatosensory cortex (SII) of three monkeys trained to switch attention between a visual task and a tactile discrimination task. We found that most neuron pairs in SII cortex fired synchronously and, furthermore, that the degree of synchrony was affected by the monkey's attentional state. In the monkey performing the most difficult task, 35% of neuron pairs that fired synchronously changed their degree of synchrony when the monkey switched attention between the tactile and visual tasks. Synchrony increased in 80% and decreased in 20% of neuron pairs affected by attention.

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Figure 1: Responses of a typical neuron pair in monkey M2.
Figure 2: Shift predictor corrected cross-correlograms (SCCCs).


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This work was supported by the NIH, the NSF and the Alfred P. Sloan Foundation. We thank J. DiCarlo, M. Usher and S. Yantis for discussions and J. Lane for technical support.

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Correspondence to E. Niebur.

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Steinmetz, P., Roy, A., Fitzgerald, P. et al. Attention modulates synchronized neuronal firing in primate somatosensory cortex. Nature 404, 187–190 (2000).

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