Brain state-dependent neuronal computation

Abstract

Neuronal firing pattern, which includes both the frequency and the timing of action potentials, is a key component of information processing in the brain. Although the relationship between neuronal output (the firing pattern) and function (during a task/behavior) is not fully understood, there is now considerable evidence that a given neuron can show very different firing patterns according to brain state. Thus, such neurons assembled into neuronal networks generate different rhythms (e.g., theta, gamma and sharp wave ripples), which sign specific brain states (e.g., learning, sleep). This implies that a given neuronal network, defined by its hard-wired physical connectivity, can support different brain state-dependent activities through the modulation of its functional connectivity. Here, we review data demonstrating that not only the firing pattern, but also the functional connections between neurons, can change dynamically. We then explore the possible mechanisms of such versatility, focusing on the intrinsic properties of neurons and the properties of the synapses they establish, and how they can be modified by neuromodulators, i.e., the different ways that neurons can use to switch from one mode of communication to the other.

A digital implementation of neuron–astrocyte interaction for neuromorphic applications

“…On the other hand, based on different neural coding schemes, the firing pattern of a neuron, which includes both the frequency and the timing of action potentials, is a key component of information processing in the brain. In the "temporal code", the precise timing of action potentials is important and in the "rate code", the information is represented by a modulation of the firing rate (Quilichini and Bernard, 2012). In this way, it was demonstrated that the astrocyte could apply feedback mechanism to regulate neuronal excitability.…”

“…This guides a new generation of technologies that can combine the strengths of industrial scale electronics with the computational performance of brains. Neuronal firing activity, which includes both the frequency and the timing of action potentials, is an essential component in information processing in the brain (Quilichini and Bernard, 2012). In addition, over the past decade, the knowledge about the diverse role of astrocytes in many facets of synaptic transmission has considerably expanded (Rusakov et al, 2011).…”

An analog astrocyte–neuron interaction circuit for neuromorphic applications

“…This will help to create a new generation of technologies that can combine the strengths of industrial scale electronics with the computational performance of brains [53,[58][59][60]. Neuronal firing activity, which includes both the frequency and the timing of action potentials, is an essential component in information processing in the brain [57,61]. In addition, over the past decade, the knowledge about the diverse role of astrocytes in many facets of synaptic transmission has considerably expanded [62][63][64].…”

“…Moreover, based on different neural coding paradigms, the firing activity of a neuron is a key component of information processing. In the "temporal code", the precise timing of action potentials is important and in the "rate code", the information is represented by a modulation of the firing rate [57]. Thus, variation in the strength of astrocyte-neuron interactions can be considered as a mechanism for information encoding.…”

Acetylcholine functionally reorganizes neocortical microcircuits

“…Neuromodulators influence cortical activity patterns (Harris and Thiele 2011), suggesting that the functional organization of cortical circuits is also modified (Quilichini and Bernard 2012). Functional connectivity within a circuit can reflect the reliable propagation of activity through the underlying synaptic structure (Ko et al 2011(Ko et al , 2013, and state-dependent modulation of this structure is a potential mechanism through which information processing can be dynamically regulated (Quilichini and Bernard 2012). Acetylcholine (ACh) is the major neurochemical substrate underlying attention (Herrero et al 2008;Paolone et al 2013), behaviorally defined as enhanced discriminability of select sensory stimuli (Cohen and Maunsell 2009;Pinto et al 2013).…”