Neural Computation, Vol 8, 511-529, Copyright © 1996 by The MIT Press

ARTICLES

Parameter extraction from population codes: a critical assessment

HP Snippe
Department of Psychology, University of Stirling, Scotland, U.K.

In perceptual systems, a stimulus parameter can be extracted by determining the center-of-gravity of the response profile of a population of neural sensors. Likewise at the motor end of a neural system, center-of-gravity decoding, also known as vector decoding, generates a movement direction from the neural activation profile. We evaluate these schemes from a statistical perspective, by comparing their statistical variance with the minimum variance possible for an unbiased parameter extraction from the noisy neuronal ensemble activation profile. Center-of-gravity decoding can be statistically optimal. This is the case for regular arrays of sensors with gaussian tuning profiles that have an output described by Poisson statistics, and for arrays of sensors with a sinusoidal tuning profile for the (angular) parameter estimated. However, there are also many cases in which center-of-gravity decoding is highly inefficient. This includes the important case where sensor positions are very irregular. Finally, we study the robustness of center-of-gravity decoding against response nonlinearities at different stages of an information processing hierarchy. We conclude that, in neural systems, instead of representing a parameter explicitly, it is safer to leave the parameter coded implicitly in a neuronal ensemble activation profile.

This article has been cited by other articles:

				S. Deneve Bayesian Spiking Neurons II: Learning Neural Comput., January 1, 2007; 20(1): 118 - 145. [Abstract] [Full Text] [PDF]

				W. M. Brown and A. Backer Optimal Neuronal Tuning for Finite Stimulus Spaces Neural Comput., July 1, 2006; 18(7): 1511 - 1526. [Abstract] [Full Text] [PDF]

				E. Guigon Computing with Populations of Monotonically Tuned Neurons Neural Comput., September 1, 2003; 15(9): 2115 - 2127. [Abstract] [Full Text]

				M. Bethge, D. Rotermund, and K. Pawelzik Optimal Short-Term Population Coding: When Fisher Information Fails Neural Comput., October 1, 2002; 14(10): 2317 - 2351. [Abstract] [Full Text]

				E. Todorov Cosine Tuning Minimizes Motor Errors Neural Comput., June 1, 2002; 14(6): 1233 - 1260. [Abstract] [Full Text]

				E. Guigon and P. Baraduc A Neural Model of Perceptual-Motor Alignment J. Cogn. Neurosci., May 1, 2002; 14(4): 538 - 549. [Abstract] [Full Text] [PDF]

				S. Wu, S.-i. Amari, and H. Nakahara Population Coding and Decoding in a Neural Field: A Computational Study Neural Comput., May 1, 2002; 14(5): 999 - 1026. [Abstract] [Full Text]

				P. Baraduc and E. Guigon Population Computation of Vectorial Transformations Neural Comput., April 1, 2002; 14(4): 845 - 871. [Abstract] [Full Text] [PDF]

				H. E. Wheat and A. W. Goodwin Tactile Discrimination of Edge Shape: Limits on Spatial Resolution Imposed by Parameters of the Peripheral Neural Population J. Neurosci., October 1, 2001; 21(19): 7751 - 7763. [Abstract] [Full Text] [PDF]

				H. Nakahara, S. Wu, and S.-i. Amari Attention Modulation of Neural Tuning Through Peak and Base Rate Neural Comput., September 1, 2001; 13(9): 2031 - 2047. [Abstract] [Full Text] [PDF]

				S. Wu, H. Nakahara, and S.-i. Amari Population Coding with Correlation and an Unfaithful Model Neural Comput., April 1, 2001; 13(4): 775 - 797. [Abstract] [Full Text]

				R. S. Petersen and M. E. Diamond Spatial-Temporal Distribution of Whisker-Evoked Activity in Rat Somatosensory Cortex and the Coding of Stimulus Location J. Neurosci., August 15, 2000; 20(16): 6135 - 6143. [Abstract] [Full Text] [PDF]

				C. W. Eurich and S. D. Wilke Multidimensional Encoding Strategy of Spiking Neurons Neural Comput., July 1, 2000; 12(7): 1519 - 1529. [Abstract] [Full Text]

				J. A. Bednar and R. Miikkulainen Tilt Aftereffects in a Self-Organizing Model of the Primary Visual Cortex Neural Comput., July 1, 2000; 12(7): 1721 - 1740. [Abstract] [Full Text]

				S. Panzeri, A. Treves, S. Schultz, and E. T. Rolls On Decoding the Responses of a Population of Neurons from Short Time Windows Neural Comput., October 1, 1999; 11(7): 1553 - 1577. [Abstract] [Full Text]

				S. R. Lehky and T. J. Sejnowski Seeing White: Qualia in the Context of Decoding Population Codes Neural Comput., August 15, 1999; 11(6): 1261 - 1280. [Abstract] [Full Text]

				E. N. Brown, L. M. Frank, D. Tang, M. C. Quirk, and M. A. Wilson A Statistical Paradigm for Neural Spike Train Decoding Applied to Position Prediction from Ensemble Firing Patterns of Rat Hippocampal Place Cells J. Neurosci., September 15, 1998; 18(18): 7411 - 7425. [Abstract] [Full Text] [PDF]