Chapter 7 Oscillatory responses and gamma band activity

‘Gamma’ band oscillatory response to chromatic stimuli in volunteers and patients with idiopathic Parkinson’s disease

“…The observation adds to the evidence suggesting partly distinct origins of the gamma-band and low-frequency VEP response components (Narici et al, 2003; Sannita, 2000; Sannita, 2005; Sannita et al, 1999, 2007), and indicates mechanisms of generation of the gamma response common to the subsystems that process contrast and colors. A functional role of gamma activity(ies) in processes such as the phase coding and bottom-up synchronization of neuronal activation, seems plausible (Adjamian et al, 2004; Bressler 1990; Bringuier et al, 1997; Cardin, Palmer, & Contreras, 2005; Engel et al, 1992a, 1992b; Fries et al, 2002; Gray, 1999; Hall et al, 2005; Jefferys et al, 1996; Liang, Bressler, Buffalo, Desimone, & Fries, 2005; Rodriguez, Kallenbach, Singer, & Munk, 2004; Sannita, 2000; Singer, 1993).…”

“…A ~20.0-40.0 Hz oscillatory component with peak frequency centered at ~25.0-35.0 Hz can be separated with negligible filter distortion from the human broad-band cortical responses to transient (reversal or onset/offset) contrast stimulation (VEP) and from the cat pattern-reversal VEPs. In man, this gamma mass response is almost entirely phase-locked to stimulus and has shorter latency than the VEP low-frequency components (Bodis-Wollner, Davis, Tzelepi, & Bezerianos, 2001; De Carli et al, 2001; Hall et al, 2005; Sannita, 2000, 2005; Sannita, Conforto, Lopez, & Narici, 1999; Sannita, Lopez, Piras, & Di Bon, 1995; Sannita et al, 2001; Tzelepi, Bezerianos, & Bodis-Wollner, 2000). The cortical source equivalents of gamma response shared the macro-topography, but had different orientation than those of the VEP low-frequency components in a neuromagnetic study on humans (Narici, Carozzo, Lopez, Ogliastro, & Sannita, 2003).…”

Neuronal Functional Diversity and Collective Behaviors

“…Mass oscillatory responses in the gamma interval are recorded in vivo in animals and humans in response to suitable visual stimulation, with the oscillatory response occurring earlier than the postsynaptic, low-frequency components and contributing to their generation. In the visual system, gamma activity reflects the global properties of the stimulus, with amplitude tuning at ∼5.0 c/deg consistent with the contrast function of the mammalian visual system, and it is thought to allow the required spatiotemporal accuracy for the activation of a cortical neuronal functional assembly (or assemblies) in response to sensory inputs or to mediate other time-related brain processes [36,40,41,46,47,[98][99][100][101][102][103].…”

“…For instance, modulation of synchronicity of responses in V 1 cortex is complementary to changes in spiking rate in the enhancement of saliency of neuronal responses [33]; as an other example, hippocampal neuronal assemblies independently code for spatial and episodic memory [34]. Gamma band (∼20-80 Hz) oscillations intrinsic to the resting neuron membrane and enhanced by synaptic interaction and network mechanisms are the suggested property of inhibitory interneuron mediation of code interaction [31,[34][35][36][37][38][39][40][41][42][43][44][45]; see [46,47] for reference.…”

“…Underlying hyperpolarizing GABA A potentials have been documented in hippocampal neuron cultures, where synchronization was lost and oscillations suppressed after receptor blockade. The frequency of oscillation is determined to a relevant extent by the cell and circuit properties [85][86][87][88][91][92][93][94][95][96][97][98][99][100]; see also [46,47] for reference. Mass oscillatory responses in the gamma interval are recorded in vivo in animals and humans in response to suitable visual stimulation, with the oscillatory response occurring earlier than the postsynaptic, low-frequency components and contributing to their generation.…”