Synaptic computation

Abstract

Neurons are often considered to be the computational engines of the brain, with synapses acting solely as conveyers of information. But the diverse types of synaptic plasticity and the range of timescales over which they operate suggest that synapses have a more active role in information processing. Long-term changes in the transmission properties of synapses provide a physiological substrate for learning and memory, whereas short-term changes support a variety of computations. By expressing several forms of synaptic plasticity, a single neuron can convey an array of different signals to the neural circuit in which it operates.

Instability of Attractors in Auto-associative Networks with Bio-inspired Fast Synaptic Noise

“…It is likely that the reported short-time synaptic noise determines the transmission of information in the brain [1,2,3,4]. By means of a modified attractor neural network, we shall illustrate here that fast synaptic noise may result in a nonequilibrium condition [6] consistent with short-time depression [5].…”

Nonequilibrium Behavior in Neural Networks: Criticality and Optimal Performance

“…For instance, the stochasticity of the opening and closing of the neurotransmitter vesicles, variation in the postsynaptic response along the dendritic tree, which in turn has several sources (e.g., variations of the glutamate concentration in the synaptic cleft) and differences in the power released from different locations on the active zone of the synapses [5]. Together with these fast synaptic changes, it has been reported that the postsynaptic response is also affected by short-time activity-dependent mechanisms which can decrease or increase the amount of available neurotransmitter and, consequently, the postsynaptic response is either depressed or facilitated [1,6]. This type of synaptic plasticity is believed to be fundamental for the development and adaptation of the nervous system, and to be at the base of higher brain functions such as learning and memory.…”

“…Recent research in neuroscience including both in vivo and in vitro experiments have demonstrated that synapses are more than simple communication lines among neurons, and that many different dynamic processes taking place in the synapses can influence and even determine different type of information processing in the brain [1]. Some of these mechanisms can occur on different time scales.…”

Phase Precession Through Synaptic Facilitation

“…Short-term depression is proposed, for instance, as a mechanism for an input-specific gain control (Abbott, Varela, Sen, & Nelson, 1997), the detection of input coherence (Tsodyks & Markram, 1997;Senn, Segev, & Tsodyks, 1998), and encoding of stimulus features in the visual cortex (Artun, Shouval, & Cooper, 1998;Buchs & Senn, 2002). Short-term facilitation is discussed, for example, as a mechanism for temporal integration of presynaptic input (Buonomano & Merzenich, 1995;Maass, Natschläger, & Markram, 2002;Abbott & Regehr, 2004). Here we propose that synaptic facilitation, for example, at the hippocampal mossy fiber (mf) synapse, allows for generating a relational spike code.…”