QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, September 29, 2004, 24(39):8551-8561; doi:10.1523/JNEUROSCI.0919-04.2004

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Paninski, L. Articles by Donoghue, J. P. Search for Related Content PubMed PubMed Citation Articles by Paninski, L. Articles by Donoghue, J. P.

 Previous Article  |  Next Article 

Behavioral/Systems/Cognitive
Superlinear Population Encoding of Dynamic Hand Trajectory in Primary Motor Cortex

Liam Paninski,¹ Shy Shoham,² Matthew R. Fellows,³ Nicholas G. Hatsopoulos,⁴ and John P. Donoghue³

¹Gatsby Computational Neuroscience Unit, University College London, London, United Kingdom WC1N 3AR, ²Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, ³Department of Neuroscience, Brown University, Providence, Rhode Island 02912, and ⁴Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois 60637

Neural activity in primary motor cortex (MI) is known to correlate with hand position and velocity. Previous descriptions of this tuning have (1) been linear in position or velocity, (2) depended only instantaneously on these signals, and/or (3) not incorporated the effects of interneuronal dependencies on firing rate. We show here that many MI cells encode a superlinear function of the full time-varying hand trajectory. Approximately 20% of MI cells carry information in the hand trajectory beyond just the position, velocity, and acceleration at a single time lag. Moreover, approximately one-third of MI cells encode the trajectory in a significantly superlinear manner; as one consequence, even small position changes can dramatically modulate the gain of the velocity tuning of MI cells, in agreement with recent psychophysical evidence. We introduce a compact nonlinear "preferred trajectory" model that predicts the complex structure of the spatiotemporal tuning functions described in previous work. Finally, observing the activity of neighboring cells in the MI network significantly increases the predictability of the firing rate of a single MI cell; however, we find interneuronal dependencies in MI to be much more locked to external kinematic parameters than those described recently in the hippocampus. Nevertheless, this neighbor activity is approximately as informative as the hand velocity, supporting the view that neural encoding in MI is best understood at a population level.

Key words: hand; motor cortex; movement; motion; motor activity; gain modulation; statistical model; correlated coding

---

Received March 12, 2004; revised August 10, 2004; accepted August 10, 2004.

This article has been cited by other articles:

				M. M. Churchland and K. V. Shenoy Temporal Complexity and Heterogeneity of Single-Neuron Activity in Premotor and Motor Cortex J Neurophysiol, June 1, 2007; 97(6): 4235 - 4257. [Abstract] [Full Text] [PDF]

				N. G. Hatsopoulos, Q. Xu, and Y. Amit Encoding of Movement Fragments in the Motor Cortex J. Neurosci., May 9, 2007; 27(19): 5105 - 5114. [Abstract] [Full Text] [PDF]

				E. Trainin, R. Meir, and A. Karniel Explaining Patterns of Neural Activity in the Primary Motor Cortex Using Spinal Cord and Limb Biomechanics Models J Neurophysiol, May 1, 2007; 97(5): 3736 - 3750. [Abstract] [Full Text] [PDF]

				B. R. Townsend, L. Paninski, and R. N. Lemon Linear Encoding of Muscle Activity in Primary Motor Cortex and Cerebellum J Neurophysiol, November 1, 2006; 96(5): 2578 - 2592. [Abstract] [Full Text] [PDF]

				T. Verstynen, T. Konkle, and R. B. Ivry Two Types of TMS-Induced Movement Variability After Stimulation of the Primary Motor Cortex J Neurophysiol, September 1, 2006; 96(3): 1018 - 1029. [Abstract] [Full Text] [PDF]

				J. Hore, M. O'Brien, and S. Watts Control of Joint Rotations in Overarm Throws of Different Speeds Made by Dominant and Nondominant Arms J Neurophysiol, December 1, 2005; 94(6): 3975 - 3986. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help