Reciprocal interaction between three areas of the visual cortex of the cat revealed with optical imaging of intrinsic signals

Reciprocal interaction between three areas of the visual cortex of the cat revealed with optical imaging of intrinsic signals

Optical imaging of intrinsic signals was used to simultaneously investigate several visual cortical areas ipsilaterally and contralaterally so that the spatial and temporal variations of the optical signals and the functional interdependence between the areas could be evaluated. The comparison between the spontaneous optical signals and the neuronal activities recorded from the local cortex showed a temporal correspondence, implying that the spontaneous optical signal is related to the local variations resulted from neuronal activities. Two rhythmic components, low frequency oscillation (LFO) and spindle wave, have been demonstrated in cat visual cortex by optical imaging of intrinsic signals at wavelength of 540 nm. In ipsilateral visual cortex, the LFO is essentially synchronized between areas 17 and 21a, while for areas 17 and 18 it is in anti-phase. The LFO and spindle wave obtained from contralateral visual areas 17 are out of phase or anti phase for 65% of the time reckoned. In order to understand the temporal and inter-area parameters of this activity, we compared the oscillatory activity of these visual cortical areas using correlation analysis. The synchrony of activation between areas 17 and 21a may reflect a synergy of function by which the form of a visual scene in the central field can be analyzed with high resolution. The anti-phase activation between areas 17 and 18, which are assumed to be the neural substrates of form and movement processing respectively, is interpreted as reflection of reciprocal inhibition between the X- and Y- channels. The possible mechanism of the periodic interhemispheric asynchrony revealed by the LFO and spindle wave is discussed.