Oscillations in Spontaneous and Visually Evoked Neuronal Activity in the Superficial Layers of the Cat's Superior Colliculus

Abstract

Oscillations are ubiquitous features of neuronal activity in sensory systems and are considered as a substrate for the integration of sensory information. Several studies have described oscillatory activity in the geniculate visual pathway, but little is known about this phenomenon in the extrageniculate visual pathway. We describe oscillations in evoked and background activity in the cat's superficial layers of the superior colliculus, a retinorecipient structure in the extrageniculate visual pathway. Extracellular single-unit activity was recorded during periods with and without visual stimulation under isoflurane anesthesia in the mixture of N2O/O2. Autocorrelation, FFT and renewal density analyses were used to detect and characterize oscillations in the neuronal activity. Oscillations were common in the background and stimulus-evoked activity. Frequency range of background oscillations spanned between 5 and 90 Hz. Oscillations in evoked activity were observed in about half of the cells and could appear in two forms —stimulus-phase-locked (10–100 Hz), and stimulus-phase-independent (8–100 Hz) oscillations. Stimulus-phase-independent and background oscillatory frequencies were very similar within activity of particular neurons suggesting that stimulus-phase-independent oscillations may be a form of enhanced “spontaneous” oscillations. Stimulus-phase-locked oscillations were present in responses to moving and flashing stimuli. In contrast to stimulus-phase-independent oscillations, the strength of stimulus-phase-locked oscillations was positively correlated with stimulus velocity and neuronal firing rate. Our results suggest that in the superficial layers of the superior colliculus stimulus-phase-independent oscillations may be generated by the same mechanism(s) that lie in the base of “spontaneous” oscillations, while stimulus-phase-locked oscillations may result from interactions within the intra-collicular network and/or from a phase reset of oscillations present in the background activity.

Infra‐slow modulation of fast beta/gamma oscillations in the mouse visual system

“…2018; Foik et al . 2018). Thus, their spatiotemporal topology is more flexible and need not necessarily reflect the underlying structural connectivity.…”

“…Fast beta/gamma oscillations typically are short-lasting events that can arise locally and transiently synchronize distant brain areas (Buzsáki, 2006). Those oscillations can be evoked by sensory stimulation (Gray et al 1989;Cardin et al 2009;Storchi et al 2017) or by cognitive tasks (Fries, 2005) but can also emerge spontaneously (Tsuji et al 2016;Chrobok et al 2018;Foik et al 2018). Thus, their spatiotemporal topology is more flexible and need not necessarily reflect the underlying structural connectivity.…”

Oscillations in the auditory system and their possible role

“…The geometry of such nuclei is organized circularly, rather than in columns as in the neocortex, which makes the summation of dendritic potentials quite small and therefore makes the LFP unpredictable. Still, this absence of oscillations is in contrast with subcortical nuclei from the visual system (Bal et al, 2000;Foik et al, 2018;Le et al, 2019).…”