Gamma and the Coordination of Spiking Activity in Early Visual Cortex

Abstract

SUMMARY Gamma components of the local field potential (LFP) are elevated during cognitive and perceptual processes. It has been suggested that gamma power indicates the strength of neuronal population synchrony, which influences the relaying of signals between cortical areas. However, the relationship between coordinated spiking activity and gamma remains unclear, and the influence on corticocortical signaling largely untested. We investigated these issues by recording from neuronal populations in areas V1 and V2 of anesthetized macaque monkeys. We found that visual stimuli that induce a strong, coherent gamma rhythm result in enhanced pairwise and higher-order V1 synchrony. This is associated with stronger coupling of V1-V2 spiking activity, in a retinotopically specific manner. Coupling is more strongly related to the gamma modulation of V1 firing than to the downstream V2 rhythm. Our results thus show that elevated gamma power is associated with stronger coordination of spiking activity both within and between cortical areas.

Cortical oscillations arise from contextual interactions that regulate sparse coding

“…1E). Recent experiments suggest that slower gamma-range oscillations are induced by the recruitment of a spatially extended neural population (5,20), an observation at odds with experimental evidence emphasizing the local nature of these oscillations (6,21); our network demonstrates how a spatially limited neural population can generate both fast and slow oscillations.…”

Theta Phase Segregation of Input-Specific Gamma Patterns in Entorhinal-Hippocampal Networks

“…While principal cells in the superficial layers of neocortex are more electrotonically compact (Zador et al, 1995), which could perhaps enable cortical circuits to more effectively employ gamma synchronization as a mechanism for selective interregional communication (Singer, 1993; Fries, 2005), this hypothesis remains hotly debated (Shadlen and Movshon, 1999; Kopell et al, 2000; Fries, 2009; Ray and Maunsell, 2010; Fell and Axmacher, 2011; Bosman et al, 2012; Akam and Kullmann, 2012; Jia et al, 2013; Srinath and Ray, 2014). In our analysis, LFP-spike coupling between CA1 units and CA3 or EC3 LFP was mostly attributable to phase-locking of interneurons (Figure 6).…”

In Vivo Magnetic Recording of Neuronal Activity

“…The separation of spikes originating from these many neurons would be a challenge. Electrophysiological recordings allow separation of a handful of spikes, based on the relatively stereotypical spike waveform of a given neuron and the fact that millisecond-precise spike coincidences of neighboring neurons occur with a very low probability of 0.01 – 0.001 (Jia et al, 2013; Kohn and Smith, 2005). Magnetic recordings would be able to benefit from the same factors, and in addition from the vectorial nature of magnetic sources and the corresponding vectorial sensitivity of the sensors.…”