Analysis of neural networks in subcortical visual structures using correlation methods

Correlation methods were used to characterize the activity of single neurons and network connections in three subcortical structures of the cat visual system. Autocorrelation analysis performed on spike trains of single cells recorded from the lateral geniculate nucleus and perigeniculate nucleus showed the presence of bursts of high-frequency oscillations ranging from 100 - 550 Hz in the spontaneous neuronal activity. Autocorrelation performed on spike trains of single cells recorded from the superior colliculus also revealed oscillations, but in the frequency range of 10-90 Hz, both in the spontaneous and visually evoked neuronal activity. The presence of oscillations was confirmed with spectral analysis and a shift predictor was used to distinguish between stimulus locked and stimulus independent oscillations in visually evoked activity. On the other hand, a crosscorrelation analysis performed on two spike trains recorded from the same electrode or pair of electrodes in the superior colliculus, revealed a common input from an external source and the presence of inhibitory interactions in the neuronal network.