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The organization of frontoparietal cortex in the tree shrew ( Tupaia belangeri ): II. Connectional evidence for a frontal‐posterior parietal network
Author(s) -
Remple Michael S.,
Reed Jamie L.,
Stepniewska Iwona,
Lyon David C.,
Kaas Jon H.
Publication year - 2007
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21226
Subject(s) - posterior parietal cortex , somatosensory system , biology , neuroscience , anatomy , cortex (anatomy) , parietal lobe , inferior parietal lobule , dorsum , functional magnetic resonance imaging
Abstract Tree shrews are small squirrel‐like mammals that are the closest living relative to primates available for detailed neurobiological study. In a recent study (Remple et al. [2006] J. Comp. Neurol. 497:133–154), we provided anatomical and electrophysiological evidence that the frontoparietal cortex of tree shrews has two motor fields (M1 and M2) and five somatosensory fields (3a, 3b, S2, somatosensory caudal area [SC], and parietal ventral area [PV]). In the present study, we injected anatomical tracers into M1, M2, 3a, 3b, SC, and posterior parietal cortex to establish the ipsilateral cortical connections of these areas. The results provide evidence for a number of new cortical areas including medial motor and somatosensory areas (MMA and MSA), three posterior parietal areas (PPd, PPv, and PPc), and an area ventral to temporal inferior cortex (TIV). M1 receives topographic projections from M2, MMA, 3a, and PPv, and nontopographic connections from the temporal anterior and dorsal areas (TA and TD), PPc, TIV, and MSA. The connections of M2 are similar to those of M1, except that M2 receives denser projections from TIV, PPc, and dorsal frontal cortex and sparser input from M1. Areas 3a, 3b, and SC receive dense topographic projections from each other, S2, and PV and sparser connections from PPd and PPv. Area 3a receives additional input from posterior parietal and temporal regions and from M1 and MMA. Overall, the frontoparietal connections of tree shrew cortex are most similar to those of prosimian primates and quite different from those of more distant relatives such as rats. J. Comp. Neurol. 501:121–149, 2007. © 2007 Wiley‐Liss, Inc.