Submitted on July 2, 2008
Revised on November 9, 2008
Accepted on December 20, 2008
Bayesian Correction for Attenuation of Correlation in Multi-Trial Spike Count Data
Sam Behseta1*, Tamara Berdyyeva2, Carl R Olson3, and Robert E. Kass3
1 California State University Fullerton
2 Center for the Neural Basis of Cognition, Carnegie Mellon University
3 Carnegie Mellon University
* To whom correspondence should be addressed. E-mail: sbehseta{at}fullerton.edu.
When correlation is measured in the presence of noise, its value is decreased. In single-neuron recording experiments, for example, the correlation of selectivity indices in a pair of tasks may be assessed across neurons but, because the number of trials is limited, the measured index values for each neuron will be noisy. This attenuates the correlation. A correction for such attenuation was proposed by Spearman more than 100 years ago, and more recent work has shown how confidence intervals may be constructed to supplement the correction. In this paper, we propose an alternative Bayesian correction. A simulation study shows that this approach can be far superior to Spearman's, both in accuracy of the correction and in coverage of the resulting confidence intervals. We demonstrate the usefulness of this technology by applying it to a set of data obtained from the frontal cortex of a macaque monkey while performing serial order and variable reward saccade tasks. There, the correction results in a substantial increase in the correlation across neurons in the two tasks.
