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Network of attention in human and macaque

開催日 2014/9/13
時間 17:10 - 19:10
会場 Room C(502)
Chairperson(s) 吉田 正俊 / Masatoshi Yoshida (自然科学研究機構 生理学研究所 / Department of Developmental Physiology, National Institute for Physiological Sciences, Japan)
Ziad Hafed (Physiology of Active Vision, Centre for Integrative Neuroscience, University of Tüebingen, Germany)

Neuronal response gain modulation around the time of microsaccades

  • S3-C-3-3
  • Ziad Hafed:1 
  • 1:Tüebingen University, Tuebingen, Germany 

Neuronal response gain modulation is a classic signature of covert visual attention. Using human psychophysics, I have recently found that visual performance changes observed in attention tasks are tightly synchronized to the occurrence of fixational microsaccades (Hafed, Neuron, 2013). While these results reveal a strong connection between subliminal motor activity and attention, the majority of neuronal studies of attention do not consider this connection. Here, I show in six different monkeys and two different brain areas related to attention, superior colliculus (SC) and frontal eye fields (FEF), that neuronal response gain modulation occurs around microsaccades, and in a manner consistent with the above human results. We found that the response of SC and FEF neurons to a visual stimulus inside their receptive fields (RFs) can be either enhanced or suppressed when the stimulus appears in close temporal proximity to microsaccades compared to when the same stimulus appears without nearby eye movements. The patterns of response modulation that we found were highly specific: SC neurons tended to exhibit response enhancement if stimulus onset occurred <100 ms before the onset of a microsaccade directed towards their RFs, but not for microsaccades opposite the RFs. The same neurons showed strong suppression if stimuli occurred <100 ms after microsaccade end. Virtually identical results were obtained from FEF, although enhancement was not as prevalent. These results reveal a surprising modulation of neuronal response gain around the time of microsaccades, and one that cannot be explained by simple saccadic suppression since we often saw enhancement instead. Given that both response enhancement (attentional allocation) and suppression (inhibition of return) are classic signatures of attention, our work suggests that attention and subliminal motor programming are more connected than previously thought. Two possible mechanisms could account for such a connection. First, corollary discharge associated with microsaccade generation could alter visual representations, much like with larger saccades. Second, oculomotor system rhythmicity (Hafed & Ignashchenkova, 2013) could be related to visual sensitivity oscillations in the brain, such that microsaccades happen at specific phases of either enhanced or reduced sensitization.

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