RESEARCH INTEREST

Representation of information in auditory and visual systems, particularly with reference to function of assemblies of neurons; models of neuronal networks.

This is a Joint-peristimulus time histogram, or JPSTH. Details

RESEARCH TECHNIQUES

Multiple microelectrodes for extracellular recording; micro and mini computers for control of experiments, analysis of relations among and patterns in spike trains, and for theoretical and simulation studies.


RESEARCH SUMMARY

Our laboratory studies the nervous system at the level of neuronal assemblies both experimentally and with computer modeling. The experiments involve technology to record in parallel the spike train activity of some 20 neurons in a small brain region .Subsequent analysis of the time structure of these spike trains allows inference of the dynamic organization among the observed neurons, and gives access to their handling of information. Modeling of networks made up of fairly realistic spiking elements (membrane time constants, synaptic currents, potassium currents, some additional channels, thresholds, etc.) allows both validation of the analysis tools used on the experimental data and also mimicking various aspects of the observed neuronal assemblies.

When a sensory-motor task is learned and performance slowly improves, the relevant domain in the cortical sensory map enlarges. A large part of our current effort is directed at the reverse of this observation: If the cortical domain is enlarged by an appropriate acute manipulation (there are several such available) will there be an improvement in a task that depends on that domain? In one series of experiments we used intra-cortical microstimulation which indeed enlarges the domain to which it is applied, but found no significant associated improvement in task performance. This may be because the manipulation is without any behavioral context. A current series of experiments is making use of lateral hypothalamic reward stimulation paired with an auditory tone to to force rapid domain enlargement; the behavioral consequences are not yet known. Other work in the lab has used muscimol (a GABA agonist) to suppress all activity in auditory cortex during task behavior. The result is total deafness, in contradiction to early literature that used cortical ablation. We also have recently been studying the role of cortico-thalamic feedback in auditory and visual systems suing experiments and modeling.

KEY WORDS: Neuronal assemblies; coding; mapping; plasticity; cortex.


KEY REFERENCES

Determination of response latency and its application to normalization of cross-correlation measures. S.N. Baker and G.L. Gerstein, Neural Computation 13: 1351-1377, 2001.

Reorganization in awake rat auditory cortex by local microstimulation and its effect on frequency discrimination behavior. S.K. Talwar and G.L. Gerstein, J. Neurophysiology 86: 1555-1572, 2001.

The role of mammalian auditory cortex in the perception of elementary sound properties. S.K. Talwar, P.G. Musial, G.L. Gerstein, J.Neurophysiology 85: 2350-2358, 2001.

Daily variation and appetitive conditioning-induced plasticity of auditory cortex receptive fields. M.A. Kisley and G.L. Gerstein, European Journal of Neuroscience 13: 1993-2003, 2001.

Signal-to-noise ratio improvement in multiple electrode recording. P.G. Musial, S.N. Baker, G.L. Gerstein, E. King and J.G. Keating, J. Neuroscience Methods 115: 29-43, 2002.

Recordings, behavior, and models related to cortico-thalamic feedback. G.L. Gerstein, K.L. Kirkland, P.G. Musial, and S.K. Talwar, Phil. Trans. R. Soc. Lond. 357: 1835-1841, 2002.