The relation of corpus callosum connections to architectonic fields and body surface maps in sensorimotor cortex of new and old world monkeys

Abstract

Corpus callosum connections of parietal and motor cortex were studied in New World owl monkeys (Aotus trivirgatus) and Old World macaque monkeys (Macaca fascicularis) after multiple injections of 3H-proline and horseradish peroxidase, HRP, into one cerebral hemisphere, and extensive microelectrode mapping of architectonic Areas 3b, 1, and 2 of the other hemisphere. Results were obtained both from parasagittal brain sections cut orthogonal to the brain surface and from sections from flattened brains cut parallel to the brain surface. Cortical fields varied in density of callosal connections, and the density of connections varied according to body part within sensory representations. Thus, Area 3b had few, Area 1 had more, and Area 2 had relatively dense callosal connections. Within each of these fields, connections were much less dense for the representations of the glabrous hand and foot and much more dense for the representations of the face and trunk. For the representation of the hand, retrogradely labeled cells were extremely sparse in Area 3b, moderately sparse in Area 1, and moderate in Area 2. There were less dense callosal connections in the hand representations of Areas 3b, 1, and 2 in macaque as compared to owl monkeys. Label in posterior parietal cortex was uneven with zones of extremely dense connections. A large region of very dense callosal connections was noted in motor cortex just medial to the probable location of the hand representation. In all regions, callosally projecting cells appeared to be more broadly distributed than callosal terminations. In no region was the discontinuous arrangement of callosal connections obviously organized into an extensive pattern of mediolateral or rostrocaudal bands or strips.

Segregation and overlap of callosal and association neurons in frontal and parietal cortices of primates: a spectral and coherency analysis

“…The callosal system of the superior parietal lobule has been described in detail (Caminiti and Sbriccoli, 1985) and will be reconsidered here only in relation to certain aspects of the interhemispheric transfer of motor behavior. In agreement with other studies, the pattern of frontal callosal connections that emerges from our work points up some of the main features of that transfer: the relative absence of callosal cells in part of the hand and foot representations of M 1 (Jenny, 1979;Jones et al, 1979;Killackey et al, 1983;Gould et al, 1986); the presence of callosal connections in more rostrally and laterally located frontal fields (Gould et al, 1986), in which additional representations of the arm and hand have been found (in area 6; Muakkassa and Strick, 1979;Gould et al, 1986;Matelli et al, 1986); the abundance of callosal projecting cells in the proximal limb, trunk, and face representations (Jones et al, 1979;Gould et al, 1986). This complex and fractionated pattern of callosal connections suggests a heterogeneity in the structural organization of the frontal lobe that is also evidenced by morphological studies (Matelli et al, 1986;Barbas and Pandya, 1987).…”

Loss of Resting Interhemispheric Functional Connectivity after Complete Section of the Corpus Callosum

“…Anatomic tracer studies in multiple species have shown limited callosal connections between corresponding distal limb motor cortices. That somatomotor synchrony is less affected by callosotomy is consistent with the existence of these "callosal holes" (Myers, 1965;Pappas and Strick, 1981;Killackey et al, 1983). Conversely, persistent somatomotor correlations after callosotomy may be caused by synchronous ascending information transmitted via somatomotor thalamocortical projections.…”

Diffuse optical tomography of pain and tactile stimulation: Activation in cortical sensory and emotional systems

“…In addition to pain, tactile stimulation of the hand results in bilateral SI activation (Hansson and Brismar 1999); this was around 20% less than the contraleral effect, which was similar to that observed in our study for brush stimuli. Anatomical studies of corpus callosum connections indicated relatively sparse connections for the glabarous hand and foot compared with the face and trunk (Killackey et al 1983). Thus, in humans multiple pathways for noxious information may exist that activate bilateral regions in the cortex (Tsuji et al 2006).…”