Organization of frontoparietal cortex in the tree shrew (Tupaia belangeri). I. Architecture, microelectrode maps, and corticospinal connections
Article first published online: 5 MAY 2006
Copyright © 2006 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 497, Issue 1, pages 133–154, 1 July 2006
How to Cite
Remple, M. S., Reed, J. L., Stepniewska, I. and Kaas, J. H. (2006), Organization of frontoparietal cortex in the tree shrew (Tupaia belangeri). I. Architecture, microelectrode maps, and corticospinal connections. J. Comp. Neurol., 497: 133–154. doi: 10.1002/cne.20975
- Issue published online: 5 MAY 2006
- Article first published online: 5 MAY 2006
- Manuscript Accepted: 14 JAN 2006
- Manuscript Revised: 15 DEC 2005
- Manuscript Received: 10 NOV 2005
- National Institutes of Health. Grant Number: NS 16446
Despite extensive investigation of the motor cortex of primates, little is known about the organization of motor cortex in tree shrews, one of their closest living relatives. We investigated the organization of frontoparietal cortex in Belanger's tree shrews (Tupaia belangeri) by using intracortical microstimulation (ICMS), corticospinal tracing, and detailed histological analysis. The results provide evidence for the subdivision of tree shrew frontoparietal cortex into seven distinct areas (five are newly identified), including two motor fields (M1 and M2) and five somatosensory fields (3a, 3b, S2, PV, and SC). The types of movements evoked in M1 and M2 were similar, but M2 required higher currents to elicit movements and had few connections to the cervical spinal cord and distinctive cyto- and immunoarchitecture. The borders between M1 and the anterior somatosensory regions (3a and 3b) were identified primarily from histological analysis, because thresholds were similar between these regions, and differences in corticospinal neuron distribution were subtle. The caudal (SC) and lateral (S2 and PV) somatosensory fields were identified based on differences in architecture and distribution of corticospinal neurons. Myelin-dense modules were identified in lateral cortex, in the expected location of the oral, forelimb, and hindlimb representations of S2, and possibly PV. Evidence for a complex primate-like array of motor fields is lacking in tree shrews, but their motor cortex shares a number of basic features with that of primates, which are not found in more distantly related species, such as rats. J. Comp. Neurol. 497:133–154, 2006. © 2006 Wiley-Liss, Inc.