Exploring the function of neural oscillations in early sensory systems

Abstract

Neuronal oscillations appear throughout the nervous system, in structures as diverse as the cerebral cortex, hippocampus, subcortical nuclei and sense organs. Whether neural rhythms contribute to normal function, are merely epiphenomena, or even interfere with physiological processing are topics of vigorous debate. Sensory pathways are ideal for investigation of oscillatory activity because their inputs can be defined. Thus, we will focus on sensory systems as we ask how neural oscillations arise and how they might encode information about the stimulus. We will highlight recent work in the early visual pathway that shows how oscillations can multiplex different types of signals to increase the amount of information that spike trains encode and transmit. Last, we will describe oscillation-based models of visual processing and explore how they might guide further research.

Independent encoding of grating motion across stationary feature maps in primary visual cortex visualized with voltage-sensitive dye imaging

“…Along the visual pathway multiplexing of oscillatory signals is a general way to increase the amount of information being transmitted (Koepsell et al, 2010). Multiplexed channels acting across various time scales were recently also observed at the subcortical level in thalamic spike trains (Koepsell et al, 2009).…”

Oscillatory phase coupling coordinates anatomically dispersed functional cell assemblies

“…Other studies used current injection to simulate synaptic input and show that cellular (33) and network (2) properties interact with the injected current to influence spiking timing (34) and stimulus discriminability (35). Finally, in vivo studies show that depth of processing varies with local oscillatory phase (15,36,37) and that oscillatory activity arises from interacting networks of multiple cell subtypes (21,(38)(39)(40). Thus, neuronal oscillations clearly have a direct causal impact upon local cortical computation.…”

Cosine Directional Tuning of Theta Cell Burst Frequencies: Evidence for Spatial Coding by Oscillatory Interference

“…The nervous system generates a multitude of oscillatory rhythms spanning a wide range of frequency bands (Buzsáki, 2006), and phase relationships among such oscillators have been proposed to encode information not only about space, but also about time (Miall, 1989;Hopfield and Brody, 2001;Matell and Meck 2004) or complex sensory stimuli (Laurent et al, 2001;Tiesinga et al, 2008;Koepsell et al, 2010). If the phase of a neural oscillator shifts smoothly in conjunction with a time-varying state variable, x, then that oscillator's frequency would inherently be modulated by dx/dt, and thereby exhibit firing properties analogous to the velocity-modulated theta cells we observed here.…”