March 20, 2014 17:00 〜 18:00
CiNet 1F Conference Room A
Affiliation of Junji Ito: Institute of Neuroscience and Medicine (INM-6) and Institute for Advanced Simulation (IAS-6), Juelich Research Centre and JARA, Juelich, Germany
Recent studies have emphasized functional roles of oscillatory neuronal activities during visual processing in natural conditions, such as free viewing of complex natural scenes or watching of natural movies.
While a number of functionally relevant frequency components has been reported in multiple frequency bands, little is known about whether the components in different frequency bands are independent or not, and if not, how they interact with each other.
We examined this phenomenon in local field potential (LFP) signals obtained from the primary visual cortex of capuchin monkeys freely viewing still images of natural scenes.
We identified eye movement related changes with respect to power and phase of the LFP signal in four dominant frequency bands: delta-theta (2-4 Hz), alpha-beta (10-13 Hz), low-gamma (20-40 Hz), and high-gamma (>100 Hz).
We found that the phase of the delta-theta band component was found to be entrained to the rhythm of the repetition of voluntary saccades, and that modulation of the power in the alpha-beta and low-gamma bands was locked to the onset of saccades.
Furthermore, the strength of the power modulation in the alpha-beta and low-gamma frequency bands was positively correlated with the strength of the phase-locking of the delta-theta oscillations.
These results suggest cross-frequency interactions in the form of phase-amplitude coupling between the slow (delta-theta) and the faster (alpha-beta and low gamma) oscillations.
We also found that the timing of neuronal spikes evoked by visual fixations during the free viewing was phase-locked to the fast oscillations.
Such cross-frequency interaction may provide a general mechanism for coordination of motor action, which occurs on the timescale of several hundred milliseconds, and spiking activity, occurring on the timescale of milliseconds, during active sensing behaviors.