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ANC Workshop: Angus Chadwick/Matthias Hennig

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  • ANC Workshop Talk
When Oct 28, 2014
from 11:00 AM to 12:00 PM
Where Room IF 4.31/4.33
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Angus Chadwick

Population Coding in Hippocampal Theta States

Neurons in the rodent hippocampus encode the animal's location in space through changes in firing rate and spike timing relative to the 8Hz theta rhythm. Populations of such neurons exhibit complex sequential activity patterns, suggesting that neurons are engaging in coordinated ensembles with collective dynamics. We propose an alternative hypothesis in which rate and temporal coding in individual cells generates these population activity patterns. We illustrate the consequences of this hypothesis for spatial coding and show that it is compatible with recent experimental findings on hippocampal theta sequences.


Matthias Hennig:

Variability and constraints in spontaneous neuronal network remodelling

Ongoing plasticity continuously remodels neural circuits, yet the behaviour and function of neuronal assemblies are generally rather stable over time. In this talk, I will addresses which factors determine this stability despite ongoing changes in single neurons and synapses. We used densely seeded dissociated hippocampal cultures plated on 4,096 channel multi-electrode arrays to monitor neural activity over the course of several days. To assess the significance of changes in firing rates and correlations, we conducted a sensitivity analysis of parametric models of the activity. While the parameters of these models, similar to neural activity, changed considerably over time, their sensitivity changed only slowly. In addition, activity changes predominantly occurred along insensitive parameter dimensions. These results show that neuronal networks can exhibit considerable remodelling over time, which is however constrained such that the overall functional network architecture is maintained.