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Wake Forest Physics…
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WFU Physics Colloquium
TITLE:
The stochastic rise-to-threshold: a fundamental neuro-computational process at multiple time scales
SPEAKER:
Dr. Emilio Salinas,
WFU Medical School Department of Neurobiology & Anatomy
TIME: Wednesday March 21, 2012 at 4:00 PM
PLACE: Room 101 Olin Physical Laboratory
Refreshments will be served at 3:30 PM in the Olin Lounge.
All interested persons are cordially invited to attend.
ABSTRACT
A typical cortical neuron is driven by thousands of synaptic inputs from other neurons, and the collective statistics of those inputs determine when the postsynaptic neuron itself fires; that is, when it produces action potentials. During such integration process, the neuron's intracellular voltage rises stochastically until it reaches a threshold value, at which point an action potential is triggered. In single neurons, this integrate-and-fire cycle takes on the order of tens of milliseconds, and very accurate models exist for describing it. More recently, however, it has become clear that processes with similar dynamics (but very different biophysical implementations) also take place at the level of local microcircuits. In that case, populations of neurons gradually increase their overall activity, and when a distinct threshold is reached, a discrete event -- for example, an eye movement -- is triggered. Such processes develop over much longer time scales, from hundreds of milliseconds to tens of seconds. Furthermore, the psychophysical behavior of subjects in numerous two-alternative choice tasks is often reproduced with great quantitative detail by simple models in which two competing integrators race toward a threshold. These results suggest that the rise-to-threshold is a fundamental computational operation implemented by neural circuits under a wide range of behavioral contexts and time scales.
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