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Independent theta phase coding accounts for CA1 population sequences and enables flexible remapping.

Chadwick A, van Rossum MC, Nolan MF - Elife (2015)

Bottom Line: These sequential representations have been suggested to result from temporally coordinated synaptic interactions within and between cell assemblies.We identify measures of global remapping and intracellular theta dynamics as critical for distinguishing mechanisms for pacemaking and coordination of sequential population activity.Our analysis suggests that, unlike synaptically coupled assemblies, independent neurons flexibly generate sequential population activity within the duration of a single theta cycle.

View Article: PubMed Central - PubMed

Affiliation: Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.

ABSTRACT
Hippocampal place cells encode an animal's past, current, and future location through sequences of action potentials generated within each cycle of the network theta rhythm. These sequential representations have been suggested to result from temporally coordinated synaptic interactions within and between cell assemblies. Instead, we find through simulations and analysis of experimental data that rate and phase coding in independent neurons is sufficient to explain the organization of CA1 population activity during theta states. We show that CA1 population activity can be described as an evolving traveling wave that exhibits phase coding, rate coding, spike sequences and that generates an emergent population theta rhythm. We identify measures of global remapping and intracellular theta dynamics as critical for distinguishing mechanisms for pacemaking and coordination of sequential population activity. Our analysis suggests that, unlike synaptically coupled assemblies, independent neurons flexibly generate sequential population activity within the duration of a single theta cycle.

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Effect of normalization factor(Nspikes).Firing rate vs time for runs with v = 50 cm/s,k = 0.7, and three different values ofNspikes.DOI:http://dx.doi.org/10.7554/eLife.03542.005
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fig2s1: Effect of normalization factor(Nspikes).Firing rate vs time for runs with v = 50 cm/s,k = 0.7, and three different values ofNspikes.DOI:http://dx.doi.org/10.7554/eLife.03542.005

Mentions: Place cells often show variations in firing rate in response to nonspatial factorsrelevant to a particular task (e.g., Wood et al.,2000; Fyhn et al., 2007; Griffin et al., 2007; Allen et al., 2012). In our model, such multiplexing ofadditional rate coded information can be achieved by varying the number of spikes perpass Nspikes without interfering with the otherparameters ϕ(x), σ,and k (Figure 2—figuresupplement 1).


Independent theta phase coding accounts for CA1 population sequences and enables flexible remapping.

Chadwick A, van Rossum MC, Nolan MF - Elife (2015)

Effect of normalization factor(Nspikes).Firing rate vs time for runs with v = 50 cm/s,k = 0.7, and three different values ofNspikes.DOI:http://dx.doi.org/10.7554/eLife.03542.005
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383210&req=5

fig2s1: Effect of normalization factor(Nspikes).Firing rate vs time for runs with v = 50 cm/s,k = 0.7, and three different values ofNspikes.DOI:http://dx.doi.org/10.7554/eLife.03542.005
Mentions: Place cells often show variations in firing rate in response to nonspatial factorsrelevant to a particular task (e.g., Wood et al.,2000; Fyhn et al., 2007; Griffin et al., 2007; Allen et al., 2012). In our model, such multiplexing ofadditional rate coded information can be achieved by varying the number of spikes perpass Nspikes without interfering with the otherparameters ϕ(x), σ,and k (Figure 2—figuresupplement 1).

Bottom Line: These sequential representations have been suggested to result from temporally coordinated synaptic interactions within and between cell assemblies.We identify measures of global remapping and intracellular theta dynamics as critical for distinguishing mechanisms for pacemaking and coordination of sequential population activity.Our analysis suggests that, unlike synaptically coupled assemblies, independent neurons flexibly generate sequential population activity within the duration of a single theta cycle.

View Article: PubMed Central - PubMed

Affiliation: Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.

ABSTRACT
Hippocampal place cells encode an animal's past, current, and future location through sequences of action potentials generated within each cycle of the network theta rhythm. These sequential representations have been suggested to result from temporally coordinated synaptic interactions within and between cell assemblies. Instead, we find through simulations and analysis of experimental data that rate and phase coding in independent neurons is sufficient to explain the organization of CA1 population activity during theta states. We show that CA1 population activity can be described as an evolving traveling wave that exhibits phase coding, rate coding, spike sequences and that generates an emergent population theta rhythm. We identify measures of global remapping and intracellular theta dynamics as critical for distinguishing mechanisms for pacemaking and coordination of sequential population activity. Our analysis suggests that, unlike synaptically coupled assemblies, independent neurons flexibly generate sequential population activity within the duration of a single theta cycle.

Show MeSH