Quantifying circularalinear associations: Hippocampal phase precession

When a rat crosses the place field of a hippocampal pyramidal cell, this cell typically fires a series of spikes. Spike phases, measured with respect to theta oscillations of the local field potential, on average decrease as a function of the spatial distance traveled. This relation between phase an...

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Bibliographic Details
Published in:Journal of neuroscience methods 2012-05, Vol.207 (1), p.113-124
Main Authors: Kempter, Richard, Leibold, Christian, Buzslki, Gyoergy, Diba, Kamran, Schmidt, Robert
Format: Article
Language:English
Subjects:
Data processing
Electrophysiological recording
Hippocampus
Nervous system
Pyramidal cells
theta rhythms
Online Access:Get full text
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Summary:When a rat crosses the place field of a hippocampal pyramidal cell, this cell typically fires a series of spikes. Spike phases, measured with respect to theta oscillations of the local field potential, on average decrease as a function of the spatial distance traveled. This relation between phase and position of spikes might be a neural basis for encoding and is called phase precession. The degree of association between the circular phase variable and the linear spatial variable is commonly quantified through, however, a linearalinear correlation coefficient where the circular variable is converted to a linear variable by restricting the phase to an arbitrarily chosen range, which may bias the estimated correlation. Here we introduce a new measure to quantify circularalinear associations. This measure leads to a robust estimate of the slope and phase offset of the regression line, and it provides a correlation coefficient for circularalinear data that is a natural analog of Pearson's product-moment correlation coefficient for linearalinear data. Using surrogate data, we show that the new method outperforms the standard linearalinear approach with respect to estimates of the regression line and the correlation, and that the new method is less dependent on noise and sample size. We confirm these findings in a large data set of experimental recordings from hippocampal place cells and theta oscillations, and we discuss remaining problems that are relevant for the analysis and interpretation of phase precession. In summary, we provide a new method for the quantification of circularalinear associations.
ISSN:0165-0270
DOI:10.1016/j.jneumeth.2012.03.007