This article is part of the supplement: Seventeenth Annual Computational Neuroscience Meeting: CNS*2008

Open Access Poster presentation

From multiple neural cortical networks to motor mechanical behavior: the importance of inherent learning over separable space-time length scales

Kanuresh Ganguly1, Elizabeth B Torres2*, Jorge V José3 and Jose M Carmena4

Author Affiliations

1 Neurology, UCSF, San Francisco, CA 94143, USA

2 Biology-CNS, CALTECH, Pasadena, CA, 91125, USA

3 Physics, Physiology and Biophysics, SUNY, Buffalo, NY, 14260, USA

4 Computer Science, Electrical Engineering, UC Berkeley, Berkeley, CA, 94720, USA

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BMC Neuroscience 2008, 9(Suppl 1):P70 doi:10.1186/1471-2202-9-S1-P70


The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2202/9/S1/P70


Published:11 July 2008

© 2008 Ganguly et al; licensee BioMed Central Ltd.

Poster presentation

An important question in neuroscience is how different cortical areas bind during the planning and execution of voluntary, goal-directed behavior. Learning visually-guided reaches can provide important theoretical and experimental insights into this problem, particularly when combined with Brain-Machine Interface (BMI) and multi-electrode measurements over extended periods of time across multiple cortical regions. We exploit the force-field paradigm [1] that alters the arm dynamics of the subject to monitor the ensuing adaptive processes in order to understand across multiple regions the differences between a habitual reach and a reach that requires learning. We quantify the translation of movement plans into their physical implementation by studying the representation of time [2] in relation of its well documented separability from the spatial components of motion trajectories [3]. Previously the internal representation of environmentally-dependent forces on position and velocity was found to be time-invariant [2]. We aim at explaining this feature in relation to the motor system's plasticity [4] during closed loop BMI. To this end we followed the evolution of tuning, mean firing rate levels and spike-time statistics across separable cell classes simultaneously recorded in the pre-motor and motor cortical regions of rhesus macaques as they adapted to new movement dynamics imposed by an external mechanical device.

We find that (1) several stable spatio-temporal representations co-exist in a given cell which permits identification and selection of different motor programs to operate the external device, and (2) these multiple representations can be extracted from the multi-electrode neuron spike patterns reflecting various spatial re-parameterizations compatible with the ones imposed by the external mechanical device. A neural theoretical formulation in terms of a Hodgkin-Huxley excitatory and inhibitory neural ring network is used [5] to model multi-electrode spiking statistics, explicitly considering the separation of different motor dynamical times.

Acknowledgements

Funding Sources NIH, NSF

References

  1. Shadmehr R, Mussa-Ivaldi FA: Adaptive representation of dynamics during learning of a motor task.

    J Neurosci 1994, 14:3208-3224. PubMed Abstract | Publisher Full Text OpenURL

  2. Conditt MA, Mussa-Ivaldi FA: Central Representation of time during motor learning.

    Proc Natl Acad Sci USA 1999, 96:11625-11630. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  3. Torres EB, Andersen RA: Space-time separation during obstacle avoidance learning in monkeys.

    J Neurophysiol 2006, 96:2613-2632. PubMed Abstract | Publisher Full Text OpenURL

  4. Carmena JM, Lebedev MA, Crist RE, O'Doherty JE, Santucci DM, Dimitrov DF, Patil PG, Henriquez CS, Nicolelis MAL: Learning to control a brain-machine interface for reaching and grasping by primates.

    PLoS Biology 2003, 1:193-208. Publisher Full Text OpenURL

  5. Tiesinga PHE, Fellous JM, Salinas E, Jose JV, Sejnowski TJ: Inhibitory Synchrony as a mechanism for attentional gain modulation.

    J Physiol (Paris) 2004, 98:296-314. PubMed Abstract | Publisher Full Text OpenURL