Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - Temporal Coding (Do behaving animals extract information from precise spike timing? – The use of temporal codes)

Teaser

Neural temporal codes have come to dominate our way of thinking on how information is coded in the brain. When precise spike timing is found to carry information, the neural code is defined as a temporal code. In spite of the importance of temporal codes, whether behaving...

Summary

Neural temporal codes have come to dominate our way of thinking on how information is coded in the brain. When precise spike timing is found to carry information, the neural code is defined as a temporal code. In spite of the importance of temporal codes, whether behaving animals actually use this type of coding is still an unresolved question. To date studying temporal codes was technically impossible due to the inability to manipulate spike timing in behaving animals. However, very recent developments in optogenetics solved this problem. Despite these modern tools, this key question is very difficult to resolve in mammals, because the meaning of manipulating a part of a neural circuit without knowledge of the neural activity of all the neurons involved in the coding is unclear
The fly is an ideal model system to study temporal codes because its small number of neurons allows for complete mapping of the neural activity of all the neurons involved. Since temporal codes are suggested to be involved in olfactory intensity coding, we will study this process. We will device a multidisciplinary approach of electrophysiology, two-photon imaging and behavior
We aim to examine for the first time directly whether temporal coding is used by behaving animals and to unravel the circuits and mechanisms that underlie intensity coding. To do so, we will manipulate the temporal codes in behaving animals and examine whether the behavioral responses change accordingly.

Work performed

We found that both excitatory and inhibitory optogentic tools when expressed in first and second order olfactory neurons proved ineffective in blocking intensity dependent odor response. We are attempting to develop novel tools based current optogentic tools as well as on modulation of presynaptic proteins to manipulate temporal action potential dynamics of post synaptic neurons (albeit in a less precise manner).

Final results

We are developing a novel model system for studying the relevance of action potentials temporal dynamics. Expected potential impact includes:
- impact on other researchers in neuroscience
- novel understanding of temporal dynamics
- novel understanding on the role of presynaptic proteins on temporal dynamics
- communication of results to general audiences through public engagement events, press releases, etc.
- training in advanced skills to staff and students