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Showing papers by "Neeraj Jain published in 2000"


Journal ArticleDOI
TL;DR: The face afferents from the trigeminal nucleus of the brainstem sprout and grow into the cuneate nucleus in adult monkeys after lesions of the dorsal columns of the spinal cord or therapeutic amputation of an arm, which may underlie the large-scale expansion of the face representation into the hand region of somatosensory cortex that follows such deafferentations.
Abstract: Somatotopic maps in the cortex and the thalamus of adult monkeys and humans reorganize in response to altered inputs. After loss of the sensory afferents from the forelimb in monkeys because of transection of the dorsal columns of the spinal cord, therapeutic amputation of an arm or transection of the dorsal roots of the peripheral nerves, the deprived portions of the hand and arm representations in primary somatosensory cortex (area 3b), become responsive to inputs from the face and any remaining afferents from the arm. Cortical and subcortical mechanisms that underlie this reorganization are uncertain and appear to be manifold. Here we show that the face afferents from the trigeminal nucleus of the brainstem sprout and grow into the cuneate nucleus in adult monkeys after lesions of the dorsal columns of the spinal cord or therapeutic amputation of an arm. This growth may underlie the large-scale expansion of the face representation into the hand region of somatosensory cortex that follows such deafferentations.

190 citations


Journal ArticleDOI
TL;DR: The organization of neocortex in the short-tailed opossum was explored with multiunit microelectrode recordings from middle layers of cortex, revealing the presence of at least two systematic representations of the contralateral body surface located in a continuous strip of cortex running from the rhinal sulcus to the medial wall.
Abstract: The organization of neocortex in the short-tailed opossum ( Monodelphis domestica ) was explored with multiunit microelectrode recordings from middle layers of cortex. Microelectrode maps were subsequently related to the chemoarchitecture of flattened cortical preparations, sectioned parallel to the cortical surface and processed for either cytochrome oxidase (CO) or NADPH-diaphorase (NADPHd) histochemistry. The recordings revealed the presence of at least two systematic representations of the contralateral body surface located in a continuous strip of cortex running from the rhinal sulcus to the medial wall. The primary somatosensory area (S1) was located medially while secondary somatosensory cortex (S2) formed a laterally located mirror image of S1. Auditory cortex was located in lateral cortex at the caudal border of S2, and some electrode penetrations in this area responded to both auditory and somatosensory stimulation. Auditory cortex was outlined by a dark oval visible in flattened brain sections....

34 citations


Journal ArticleDOI
TL;DR: It is demonstrated that NADPHd Type I neurons are not homogeneously distributed in the isocortex of these mammals: rats, marmosets and opossums, and that the latter are considered to have more 'generalized' brains.

25 citations