Spike Timing and Synaptic Plasticity

A NIPS*99 Workshop organized by Larry Abbott and Paul Munro

Abstract

Recent experiments have characterized a form of long-term synaptic modification that depends on the relative timing of pre- and postsynaptic action potentials. Synapses are strengthened if presynaptic action potentials precede postsynaptic action potentials by less than about 20-30 ms and are weakened if, instead, presynaptic action potentials follow postsynaptic spikes by an equivalent interval. This form of synaptic modification has important implications for theoretical studies of development and learning through synaptic plasticity.

Hebbian learning in neural networks requires both correlation-based synaptic plasticity and a mechanism that induces competition between different synapses. Spike-timing-dependent synaptic plasticity is especially interesting because it combines both of these elements in a single synaptic modification rule. Competition arises because different synapses compete to control the timing of postsynaptic spikes in order to increase their strengths. This competition is equivalent to that produced by a subtractive constraint on the summed synaptic strengths of the postsynaptic neuron.

Temporally dependent synaptic plasticity is attracting a rapidly growing amount of attention in the computational neuroscience community. The change in synaptic efficacy arising from this form of plasticity is highly sensitive to temporal correlations between different presynaptic spike trains. Furthermore, it can generate asymmetric and directionally selective receptive fields, a result supported by experiments on experience-dependent modifications of hippocampal place fields. Finally, spike-timing-dependent plasticity automatically balances excitation and inhibition producing a state in which neuronal responses are rapid but highly variable.

The major goals of the workshop are:

To review current experimental results on spike-timing-dependent synaptic plasticity.
To discuss models and mechanisms for this form of synaptic plasticity.
To explore its implications for development and learning in neural networks.

+++++++++++++++++++++++++++++++++++++++++

Tentative Presentation Schedule

(click here for list of abstracts or on the name of a person to jump to that presenter's abstract)

Morning Session (7:30AM - 11:00AM):

7:30 Welcome and Introduction (Munro and Abbott) (20 min)
7:50 Chip Levy The Time Span of Associative Synaptic Modification is Substantially Amplified by Neural Interactions
8:15 Mu-Ming Poo Correlated Activity and Long-term Synaptic Modifications - Hebb's Postulate Revisited
8:40 Richard Kempter Intrinsic Rate Normalization by Hebbian Rules: Spike-Based vs. Rate-Based Learning
9:05 BREAK
9:20 Dan Feldman Long-term plasticity induced by action potential-EPSP timing at layer II/III pyramidal cells in rat somatosensory cortex.
9:45 Sen Song Spike-Timing Dependent Synaptic Plasticity Enables Groups of Correlated Neurons to Supervise Network Learning
10:10 Kevin Franks Simulated Dendritic Ca Influx through Ligand- and Voltage-Gated Channels.
10:35 Discussion (25 min, more or less)

Afternoon Session (4:30PM-7:00PM):

4:30 Mayank Mehta Effect of LTP on Spatio-Temporal Structure of Receptive Fields: Hippocampal Lessons for V1
4:55 Misha Tsodyks An Algorithm for Modifying Neurotransmitter Release Probability Based on Pre- and Post-Synaptic Spike Timing
5:20 Rajesh Rao Predictive Learning of Direction Selectivity in Recurrent Cortical Circuits
5:45 David Horn Distributed Synchrony in a Hebbian Cell Assembly of Spiking Neurons
6:10 BREAK
6:25 General Discussion (35 min)