Somatotopic maps in the cortex and thalamus of adult monkeys humans reorganize response to altered inputs. After loss sensory afferents from forelimb because transection dorsal columns spinal cord, therapeutic amputation an arm or roots peripheral nerves, deprived portions hand representations primary somatosensory (area 3b), become responsive inputs face any remaining arm. Cortical subcortical mechanisms that underlie this reorganization are uncertain appear be manifold. Here we show...

Adult brains undergo large-scale plastic changes after peripheral and central injuries. Although it has been shown that both the cortical thalamic representations can reorganize, uncertainties exist regarding extent, nature, time course of at each level. We have determined how in somatosensory area 3b ventroposterior (VP) nucleus thalamus are affected by long standing unilateral dorsal column lesions cervical levels macaque monkeys. In monkeys with recovery periods 22–23 months, intact face...

The nodes of a parietal–frontal pathway that mediates grasping in primates are anterior intraparietal area (AIP) and ventral premotor cortex (PMv). Nevertheless, multiple somatosensory motor representations the hand, parietal frontal cortex, respectively, suggest additional pathways remain unrealized. We explored this possibility macaque monkeys by injecting retrograde tracers into grasp zones identified primary (M1), PMv, 2 with long train electrical stimulation. M1 zone was densely...

Abstract In order to determine the relationship of superior colliculus inputs thalamic neurons projecting middle temporal visual area (MT), injections wheat germ agglutinin conjugated with horseradish peroxidase were placed in three owl monkeys, Fast Blue MT. The locations labelled terminals and posterior thalamus related four architectonically distinct nuclei inferior pulvinar (Stepniewska & Kaas, Vis. Neurosci. 14 , pp.1043–1060, 1997). MT largely medial nucleus pulvinar. A few found...

Neuronal activity was recorded in the ventral premotor cortex of one monkey (Macaca fascicularis) trained to exert finely graded forces with thumb and index finger on a force sensor visuomotor step-tracking paradigm. Trials two or three consecutive ramp-and-hold steps were presented randomly. Most neurons displayed similar discharge patterns two- three-step trials assigned following classes: phasic, phasic-tonic, tonic, decreasing, mixed. For more than 50% tonic activity, positive negative...

Patterns of terminals labeled after WGA-HRP injections in the superior colliculus (SC) squirrel monkeys and macaque monkeys, DiI application marmosets, were related to architecture pulvinar dorsal lateral geniculate nucleus (LGN). In all studied species, SC projects densely two architectonic subdivisions inferior pulvinar, posterior (PIp) central medial (PIc m ). These projection zones expressed substance P. Thus, sections processed for P reveal termination pulvinar. The subdivision PIm,...

We determined the somatotopy of face and oral cavity representation in cortical area 3b New World owl monkeys squirrel monkeys. Area is apparent as a densely myelinated strip brain sections cut parallel to surface flattened cortex. A narrow myelin-light septum that we have termed "hand-face septum" separates hand from more lateral mouth representation. The further divided into series myelin-dense ovals. show three ovals adjacent correspond upper face, lip, chin plus lower whereas or four...

In the primary visual area of macaques and other monkeys, layer 4A is a mosaic separate tissue compartments related to parvocellular (P) magnocellular (M) layers lateral geniculate nucleus. This resembles honeycomb, with thin walls that receive direct P inputs cores consisting columns dendrites cell bodies ascending from 4B, receives indirect M inputs. To determine whether apes humans have macaque-like 4A, we examined in humans, chimpanzees, an orangutan, Old World New monkeys. Apes lacked...

Abstract Microelectrode mapping methods were used to define the parietal ventral somatosensory area (PV) on upper bank of lateral sulcus in five marmosets (Callithrix jacchus). In same animals, neuroanatomical tracers placed into electrophysiologically identified sites PV and/or second (S2). Foci anterograde and retrograde label related electrophysiological maps cortical areas thalamic architecture. The results lead following conclusions: (1) Multiunit recordings from cortex demonstrate that...

The organization of primary motor cortex (M1) adult macaque monkeys was examined years after therapeutic amputation part a limb or digits. For each case, large number sites in M1 were electrically stimulated with penetrating microelectrode, and the evoked movements levels current needed to evoke recorded. Results from four loss forelimb near above elbow show that extensive regions formerly devoted missing hand stump adjoining shoulder. Threshold for comparable those normal arm movements. Few...

Abstract The organization of anterior and lateral somatosensory cortex was investigated in titi monkeys ( Callicebus moloch ). Multiunit microelectrode recordings were used to identify multiple representations the body, anatomical tracer injections reveal connections. (1) Representations face identified areas 3a, 3b, 1, S2, parietal ventral area (PV). In represented from chin/lower lip upper neck/upper a rostrocaudal sequence. representation 1 mirrored that 3b. Another located 3a. Adjoining...

Despite the lack of ipsilateral receptive fields (RFs) for neurons in hand representation area 3b primary somatosensory cortex, interhemispheric interactions have been reported to varying degrees. We investigated spatiotemporal properties these determine following: response types, timing between stimuli evoke strongest bimanual interactions, topographical distribution effects, and their dependence on similarity stimulus locations two hands. analyzed magnitudes latencies single multineuron...

Tactile discrimination depends on integration of information from the discrete receptive fields (RFs) peripheral sensory afferents. Because this is processed over a hierarchy subcortical nuclei and cortical areas, likely occurs at multiple levels. The current study presents results indicating that neurons across most extent hand representation in monkey primary somatosensory cortex (area 3b) interact, even when these have separate RFs. We obtained simultaneous recordings by using...

Abstract Connections of representations the teeth and tongue in primary somatosensory cortex (area 3b) adjoining were revealed owl, squirrel, marmoset monkeys with injections fluorescent tracers. Injection sites identified by microelectrode recordings from neurons responsive to touch on or tongue. Patterns cortical label related myeloarchitecture sections cut parallel surface flattened cortex, coronal thalamus processed for cytochrome oxidase (CO). Cortical a caudorostral series myelin dense...

An incomplete lesion of the ascending afferents from hand in dorsal columns spinal cord monkeys is followed after weeks recovery by a reactivation much territory representations primary somatosensory cortex (area 3b). However, relationship between extent column and amount cortical has not been clear. Largely, this due to uncertainties about axon sparing lesions. Here, we unilaterally sectioned cervical (C4–C6) adult squirrel monkeys. After recovery, cholera toxin subunit B (CTB) was injected...

Somatosensory cortices of adult primates reactivate over time after sensory loss. The course and the neural mechanisms underlying cortical reactivation are not well understood. Here we report that longitudinal high-resolution functional magnetic resonance imaging (fMRI) studies on anesthetized squirrel monkeys revealed dynamic reorganizations digit activations in area 3b, within 2 months severely disrupting afferent inputs by dorsal column section. We found regions which were disrupted...

Significance Nearly all mammals have tactile hairs. Distinct modular representations of the vibrissae within central nervous system been found in five mammalian orders (Marsupialia, Carnivora, Eulipotyphla, Lagomorpha, Rodentia). This work documents vibrissae-related modules a sixth order: Primata. The presence subcortical barrel-like prosimian galagos suggests broad similarities processing sensory information among rodents and primates. Additionally, thalamic “galagounculus” appears to show...

Lesions of the dorsal columns spinal cord in adult macaque monkeys lead to loss hand inputs and large-scale expansion face region somatosensory cortex. Inputs from alternate pathways do not reactivate deafferented regions area 3b. Here, we determined how transections done within a few days after birth affect developing Dorsal were transected between 3rd 12th postnatal day (PND), cortex was mapped when macaques over 3 y old. There two distinct outcomes depending on age at time lesion. In...

Abstract In the present study, we determined anatomic relationships between somatosensory and motor pathways within ventrolateral (VL) thalamic nuclei of thalamus macaque monkeys. labeling experiments, four monkeys ( Macaca mulatta ) received injections biotinylated dextran amine wheat germ agglutinin conjugated to horseradish peroxidase into cerebellar or internal segment globus pallidus cervical segments spinal cord, respectively. Each tracer was visualized in brain sections by...

Receptive fields of neurons in somatosensory area 3b monkeys are typically described as restricted to part a single digit or palm pad. However, such likely involved integrating stimulus information from across the hand. To evaluate this possibility, we recorded anesthetized owl with 100-electrode arrays, stimulating two hand locations electromechanical probes simultaneously asynchronously. Response magnitudes and latencies single- multiunits varied conditions, multiunit responses were...

ABSTRACT The ventral posterior nucleus of thalamus sends highly segregated inputs into each digit representation in area 3b primary somatosensory cortex. However, the spatial organization connections that link representations areas with other is less understood. Here we examined cortical to individual four squirrel monkeys and one prosimian galago. Retrograde tracers were injected neurophysiologically defined digits 3b. Cortical tissues cut parallel surface some cases showed feedback...