[The selective intensification of polysynaptic interhemispheric connections with latencies that are multiples of gamma-oscillation periods]

Abstract

The high-effective polysynaptic transcallosal connections were revealed in the motor cortex of anesthetized rats. Polysynaptic connections were manifested in crosscorrelation histograms as high narrow peaks of width 1-2 ms and latencies up to the end of the analyzed interval in 50 ms. In most cases the polysynaptic transcallosal connections were reciprocal. The incidence of transcallosal polysynaptic connections was twice as high as of the ipsilateral. Gamma oscillations were observed in the same neural assemblies. Interhemispheric oscillations were 1.5-fold more frequent than the ipsilateral ones. The peak latencies were multiples of gamma-oscillation periods. The distribution of peak latencies was similar to the distribution of gamma oscillations. It was suggested that synchronous discharges in neurons in a polysynaptic interhemispheric pathway in consequence of gamma oscillations cause potentiation in efficacy of neural connections, which promotes the high-effective transmission of a signal from one hemisphere to another.