In this meeting we will talk about the classical theory of sensory coding derived from Lord Adrian's early concepts of sensory coding. The rate-coding, or frequency-coding hypothesis was used to model the firing patterns of sensory receptors in the visual system and other similar systems. Rate coding will serve as an important backdrop for our understanding of sensory function. In this meeting we will discuss classical concepts: the relationship between stimulus intensity and firing frequency, intensity perception and firing frequency; the Weber-Fechner relationship. We will discuss the integrate and fire model of sensory coding. We will discuss Heeger's review of the Integrate and Fire Model.
(Adrian, 1934; Fuortes, 1958; Kiang, 1965; Perkel and Bullock, 1968; Knight, 1972; Uttal, 1973, Chapter 6: pp. 232-336; Ratliff, 1974; Heeger, 1997; Rieke, 1997 Chapter 1).
There are two articles for review.
1. Riehle, A., Grun, S., Diesmann, M. and Aertsen, A. (1997). Spike synchronization and rate modulation differentially involved in motor cortical function. Science 278, 1950-3. You will need to print this article in color or read it from the original or from the website.
2. Diesmann, M., Gewaltig, M. O. and Aertsen, A. (1999). Stable propagation of synchronous spiking in cortical neural networks. Nature 402, 529-33.
In this meeting, we will discuss a new method designed to compare the differences between two spike trains. "A Novel Spike Distance" uses a remarkably simple algorithm to compare the timing of two different spike trains to see if they differ from one another. The beauty of the method is that it is computationally simple, yet adaptable to physiological systems. (Presented by Bruce Land)
We will examine two applications: one study looks at the temporal patterns of discharges generated by electric fish (a study done by Bruce Carlson); the second is a study of a motion-sensing circuit in the fly visual system (a modeling study by Egelhaaf's group in Bielefeldl).
Bruce Carlson will explore Michael Paulin's digital filtering of spike train paper which considers a number of convolution kernels for generating spike density functions. He will use this technique to study the form and stereopy of electric fish spike trains used as social communication signals.
We will also discuss general topics of how one measures "instantaneous frequency", how one computes a "spike density function". There will be Matlab examples.
We will explore different algorithms for spike rate analysis.
Paulin, M. G. (1992). Digital filters for firing rate estimation. Biol Cybern 66, 525-31.
J., Egelhaaf, M. and Warzecha, A. K. (2001). Membrane potential
fluctuations determine the precision of spike timing and synchronous
activity: a model study. J Comput Neurosci 10, 79-97.
van Rossum, M. C. (2001). A novel spike distance. Neural Comput 13, 751-63.
We continue our discussion of spike train analysis with an analysis of cvan Rossum (2001)'s paper on distance analysis of spike times: "A Novel Spike Distance".
For some time-coding systems, the precision of temporal analysis is far less than the duration of a single spike. For example, sound localization using interaural time differences requires estimating time to an accurary of 10 microseconds or so, while the duratino of the action potential is 100 times greater. In vision, the ability to resolve spatial information finer than that of the spacing of the individual cones is referred to as visual hyperacuity. By analogy, measurements of timing with great accuracy is called temporal hyperacuity. Some of the best acknowledged cases of temporal hyperacuity come from the auditory and electrosenory systems of bats, owls and electric fish. In this meeting, we discuss the jamming avoidance response of electric fish which has a temporal acuity of 0.2 microseconds.
M. (1997). Sensory hyperacuity in the jamming avoidance response
of weakly electric fish. Current Opinion in Neurobiology 7, 473-479.
Rose, G. and Heiligenberg, W. (1985). Temporal hyperacuity in the electric sense of fish. Nature 318, 178-80.
Comments on this web site should be directed to Carl D. Hopkins