Short-Term Synaptic Plasticity Orchestrates the Response of Pyramidal Cells and Interneurons to Population Bursts

Abstract

Abstract. The synaptic drive from neuronal populations varies considerably over short time scales. Such changes in the pre-synaptic rate trigger many temporal processes absent under steady-state conditions. This paper examines the differential impact of pyramidal cell population bursts on post-synaptic pyramidal cells receiving depressing synapses, and on a class of interneuron that receives facilitating synapses. In experiment a significant shift of the order of one hundred milliseconds is seen between the response of these two cell classes to the same population burst. It is demonstrated here that such a temporal differentiation of the response can be explained by the synaptic and membrane properties without recourse to elaborate cortical wiring schemes. Experimental data is first used to construct models of the two types of dynamic synaptic response. A population-based approach is then followed to examine analytically the temporal synaptic filtering effects of the population burst for the two post-synaptic targets. The peak-to-peak delays seen in experiment can be captured by the model for experimentally realistic parameter ranges. It is further shown that the temporal separation of the response is communicated in the outgoing action potentials of the two post-synaptic cells: pyramidal cells fire at the beginning of the burst and the class of * To whom correspondence should be addressed. 324 Richardson et al.interneuron receiving facilitating synapses fires at the end of the burst. The functional role of such delays in the temporal organisation of activity in the cortical microcircuit is discussed.

Dopaminergic modulation of short-term synaptic plasticity at striatal inhibitory synapses

“…Although pre-and postsynaptic actions of dopamine have been described (24,32,37,38), a global action with a potential impact at the circuit level is not known. Here we show that STD between SPNs can be regulated by the dopaminergic system (6,32,39).…”

“…This change would make the circuit suitable to respond to sudden fast commands (48) and subtle changes in frequency (dynamic component), helping to balance inputs of different strengths (6,9,39). However, D 2 -class receptors decrease STD, perhaps setting the circuit to keep responding to and transferring a continuous basal level of activity (static or tonic component) (6,9,39). STD modulation was demonstrated by dual (unitary) recordings between SPNs and by field stimulation of groups of afferents arising from striofugal axons stimulated at the GP.…”

“…STP bestows circuits with functional capabilities such as detection of sudden changes, filtering, and fidelity transfer (5)(6)(7)(8). Short-term depression (STD) is a form of STP.…”

“…Short-term depression (STD) is a form of STP. STD gives networks dynamic gain-control and filtering capabilities that facilitate synchronization (5,6,9,10). It is little known what variables regulate STD.…”

Why the Realism Debate Matters for Science Policy: The Case of the Human Brain Project

“…Most of Markram's own work, for example, exemplified successful computational representations of neurotransmitter release probabilities (Senn et al 2001), generic neural microcircuits , short-term synaptic plasticity (Richardson et al 2005), and many other phenomena. More acutely, the HBP explicitly aims to build upon the Blue Brain Project, which successfully modeled approximately thirty thousand neurons of the neocortical column in mice.…”