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Paul Khayat, Julio Martinez-Trujillo; Coding of changes in motion direction by local field potentials in primate area MT. Journal of Vision 2013;13(9):227. doi: 10.1167/13.9.227.
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© ARVO (1962-2015); The Authors (2016-present)
In primate area MT, direction-selective neurons convey information about a stimulus’ motion direction, as early as in their initial response. These neurons may also selectively signal transient changes in motion direction by increasing or decreasing their firing rate depending on whether the direction change deviated closer to or further away from their preferred direction. These properties may thus serve to detect and discriminate changes in a stimulus’ feature. Another potential source of neuronal encoding of motion direction relies on the activity of local field potentials (LFPs). Indeed, LFPs in area MT are tuned for motion direction, in a frequency-dependent manner. It is, however, unclear whether LFPs can provide a reliable signal to detect and discriminate changes in a stimulus’ feature. To investigate this issue, we recorded LFPs and spiking activity of direction-selective neurons in area MT of monkeys trained to covertly detect a 30-degree motion direction change in one of two moving RDPs. On each trial, both RDPs moved either in the preferred or antipreferred (AP) direction, and thus the actual motion direction after the change deviated away from either the preferred or the AP direction. Across the neuronal population (n=73), the motion direction change evoked a significant (p<0.05) decrease or increase in firing rates when the change deviated the motion direction away from preferred and AP, respectively. The direction change also induced changes in the LFP power in all frequency bands. However, only the gamma-band power reflected the identity of the change, being significantly larger when the change deviated the motion direction away from AP compared to away from preferred. These results indicate that the detection of transient stimulus changes can be encoded by LFPs in all frequency bands, while the discrimination of the type of change may be encoded by LFPs in the gamma band.
Meeting abstract presented at VSS 2013
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