This article discusses the compositional structure of hand movements by analyzing and modeling neural and behavioral data obtained from experiments where a monkey (Macaca fascicularis) performed scribbling movements induced by a search task. Using geometrically based approaches to movement segmentation, it is shown that the hand trajectories are composed of elementary segments that are primarily parabolic in shape. The segments could be categorized into a small number of classes on the basis of decreasing intra-class variance over the course of training. A separate classification of the neural data employing a hidden Markov model showed a coincidence of the neural states with the behavioral categories. An additional analysis of both types of data by a data mining method provided evidence that the neural activity patterns underlying the behavioral primitives were formed by sets of specific and precise spike patterns. A geometric description of the movement trajectories, together with precise neural timing data indicates a compositional variant of a realistic synfire chain model. This model reproduces the typical shapes and temporal properties of the trajectories; hence the structure and composition of the primitives may reflect meaningful behavior.
Keywords: voluntary-movements, scribbling, compositionality, hand-motion-model, synfire chains, motion-primitives
Citation: Abeles M, Diesmann M, Flash T, Geisel T, Herrmann M and Teicher M (2013) Compositionality in neural control: an interdisciplinary study of scribbling movements in primates. Front. Comput. Neurosci. 7:103. doi: 10.3389/fncom.2013.00103
Received: 18 May 2013; Paper pending published: 11 June 2013;
Accepted: 11 July 2013; Published online: 12 September 2013.
Edited by:Martin Giese, University Clinic Tuebingen, Germany
Reviewed by:Alessandro Treves, Scuola Internazionale Superiore di Studi Avanzati, Italy
Copyright © 2013 Abeles, Diesmann, Flash, Geisel, Herrmann and Teicher. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Moshe Abeles, Gonda Brain Research Center, Bar-Ilan University, Max ansAnna Wb Str., 52900 Ramat-Gan, Israel e-mail: firstname.lastname@example.org