Gamma Rhythmic Bursts: Coherence Control in Networks of Cortical Pyramidal Neurons

Abstract

Much evidence indicates that synchronized gamma-frequency (20-70 Hz) oscillation plays a significant functional role in the neocortex and hippocampus. Chattering neuron is a possible neocortical pacemaker for the gamma oscillation. Based on our recent model of chattering neurons, here we study how gamma-frequency bursting is synchronized in a network of these neurons. Using a phase oscillator description, we first examine how two coupled chattering neurons are synchronized. The analysis reveals that an incremental change of the bursting mode, such as from singlet to doublet, always accompanies a rapid transition from antisynchronous to synchronous firing. The state transition occurs regardless of what changes the bursting mode. Within each bursting mode, the neuronal activity undergoes a gradual change from synchrony to antisynchrony. Since the sensitivity to Ca(2+) and the maximum conductance of Ca(2+)-dependent cationic current as well as the intensity of input current systematically control the bursting mode, these quantities may be crucial for the regulation of the coherence of local cortical activity. Numerical simulations demonstrate that the modulations of the calcium sensitivity and the amplitude of the cationic current can induce rapid transitions between synchrony and asynchrony in a large-scale network of chattering neurons. The rapid synchronization of chattering neurons is shown to synchronize the activities of regular spiking pyramidal neurons at the gamma frequencies, as may be necessary for selective attention or binding processing in object recognition.

Toward a developmental neurobiology of autism

“…In the hippocampus, synchronous gamma oscillation is considered to occur through the GABA A receptor-mediated mutual inhibition among interneurons [Buhl et al, 1994;Cobb et al, 1995;Freund and Buzsaki, 1996]. In the neocortex; it is known that a class of pyramidal neurons termed fast rhythmic bursting cells or "chattering" neurons synchronize their activities at gamma frequencies and are thought to be necessary for selective attention or binding processing in object recognition [Aoyagi et al, 2003]. Therefore, a slight disruption of the balance between excitation and inhibition in the cortex could have dramatic consequences on the function of the neuronal networks underlying perception and attention.…”

Synchronous and asynchronous bursting states: role of intrinsic neural dynamics

“…Since the mathematical details of this model have been published elsewhere (Aoyagi et al 2002(Aoyagi et al , 2003, below we list only the parameter values that were different from the previous ones: T = 309.16, K CAN = 13.16 μM and g CAN = 113 or 170 (two types of doublet) mS/cm 2 .…”

“…Our previous study of single-compartment CAN current model has revealed that PRCs for burst firing can in general show a broad peak in the inter-burst interval and a sharp peak in the interval within a burst (Aoyagi et al 2003). The two peaks play differential and PRCs (lower panels) during one bursting cycle were calculated in singlet, doublet near the singlet, doublet near the triplet, and triplet bursting states, respectively, using a neuron model proposed by Izhikevich (2003).…”

“…Other studies suggested that the persistent sodium (NaP) current and the electronic interplay between soma and dendrite are crucial for FRB (Wang 1999;Brumberg et al 2000;Traub et al 2003). Therefore we analyzed the synchronization properties of two types of neuron models when the same type of neurons were coupled via AMPA receptor-mediated excitatory synapses (Aoyagi et al 2003;Takekawa et al 2004). The coupled neuron system of the CAN current-based single-compartment model underwent an exchange of the stability from anti-phase (with π phase lag) to in-phase (with 0 phase lag) synchronous firing when the bursting mode, or the number of spikes per burst, increased (Aoyagi et al 2003).…”

“…Therefore we analyzed the synchronization properties of two types of neuron models when the same type of neurons were coupled via AMPA receptor-mediated excitatory synapses (Aoyagi et al 2003;Takekawa et al 2004). The coupled neuron system of the CAN current-based single-compartment model underwent an exchange of the stability from anti-phase (with π phase lag) to in-phase (with 0 phase lag) synchronous firing when the bursting mode, or the number of spikes per burst, increased (Aoyagi et al 2003). By contrast, the NaP current-based twocompartment neuron model showed neither in-phase nor anti-phase phase-locked state in many cases, and the stability exchanges between them were also less evident (Takekawa et al 2004).…”