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ABSTRACT: Motor output capabilities of the forelimb representation of dorsal motor area (PMd) and ventral motor area (PMv) were compared with primary motor cortex (M1) in terms of latency, strength, sign, and distribution of effects. Stimulus-triggered averages (60 microA) of electromyographic activity collected from 24 forelimb muscles were computed at 314 tracks in 2 monkeys trained to perform a reach-to-grasp task. The onset latency and magnitude of facilitation effects from PMd and PMv were significantly longer and 7- to 9-fold weaker than those from M1. Proximal muscles were predominantly represented in PMd and PMv. A joint-dependent flexor or extensor preference was also present. Distal and proximal muscle representations were intermingled in PMd and PMv. A gradual increase in latency and decrease in magnitude of effects were observed in moving from M1 surface sites toward more anterior sites in PMd. For many muscles, segregated areas producing suppression effects were found along the medial portion of PMd and adjacent M1. Although some facilitation effects from PMd and PMv had onset latencies as short as those from M1 in the same muscle, suggesting equal direct linkage, the vast majority had properties consistent with a more indirect linkage to motoneurons either through corticocortical connections with M1 and/or interneuronal linkages in the spinal cord.
Cerebral Cortex 07/2009; 20(1):169-86. · 6.54 Impact Factor
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ABSTRACT: Neuroimaging studies in stroke survivors have suggested that adaptive plasticity occurs following stroke. However, the complex temporal dynamics of neural reorganization after injury make the interpretation of functional imaging studies equivocal. In the present study in adult squirrel monkeys, intracortical microstimulation (ICMS) techniques were used to monitor changes in representational maps of the distal forelimb in the supplementary motor area (SMA) after a unilateral ischemic infarct of primary motor (M1) and premotor distal forelimb representations (DFLs). In each animal, ICMS maps were derived at early (3 wk) and late (13 wk) postinfarct stages. Lesions resulted in severe deficits in motor abilities on a reach and retrieval task. Limited behavioral recovery occurred and plateaued at 3 wk postinfarct. At both early and late postinfarct stages, distal forelimb movements could still be evoked by ICMS in SMA at low current levels. However, the size of the SMA DFL changed after the infarct. In particular, wrist-forearm representations enlarged significantly between early and late stages, attaining a size substantially larger than the preinfarct area. At the late postinfarct stage, the expansion in the SMA DFL area was directly proportional to the absolute size of the lesion. The motor performance scores were positively correlated to the absolute size of the SMA DFL at the late postinfarct stage. Together, these data suggest that, at least in squirrel monkeys, descending output from M1 and dorsal and ventral premotor cortices is not necessary for SMA representations to be maintained and that SMA motor output maps undergo delayed increases in representational area after damage to other motor areas. Finally, the role of SMA in recovery of function after such lesions remains unclear because behavioral recovery appears to precede neurophysiological map changes.
Journal of Neurophysiology 08/2008; · 3.32 Impact Factor
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ABSTRACT: Our earlier efforts to document the cortical connections of the ventral premotor cortex (PMv) revealed dense connections with a field rostral and lateral to PMv, an area we called the frontal rostral field (FR). Here, we present data collected in FR using electrophysiological and anatomical methods. Results show that FR contains an isolated motor representation of the forelimb that can be differentiated from PMv based on current thresholds and latencies to evoke electromyographic activity using intracortical microstimulation techniques. In addition, FR has a different pattern of cortical connections compared with PMv. Together, these data support that FR is an additional, previously undescribed motor-related area in squirrel monkeys.
Cerebral Cortex 05/2008; 18(12):2719-28. · 6.54 Impact Factor
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Ann M Stowe,
Erik J Plautz,
Phuong Nguyen, Shawn B Frost,
Ines Eisner-Janowicz,
Scott Barbay,
Numa Dancause,
Anirban Sensarma,
Michael D Taylor,
Elena V Zoubina,
Randolph J Nudo
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ABSTRACT: Clinical and experimental data support a role for the intact cortex in recovery of function after stroke, particularly ipsilesional areas interconnected to the infarct. There is, however, little understanding of molecular events in the intact cortex, as most studies focus on the infarct and peri-infarct regions. This study investigated neuronal immunoreactivity for hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2) in remote cortical areas 3 days after a focal ischemic infarct, as both HIF-1alpha and VEGFR-2 have been implicated in peri-infarct neuroprotection. For this study, intracortical microstimulation techniques defined primary motor (M1) and premotor areas in squirrel monkeys (genus Saimiri). An infarct was induced in the M1 hand representation, and immunohistochemical techniques identified neurons, HIF-1alpha and VEGFR-2. Stereologic techniques quantified the total neuronal populations and the neurons immunoreactive for HIF-1alpha or VEGFR-2. The results indicate that HIF-1alpha upregulation is confined to the infarct and peri-infarct regions. Increases in VEGFR-2 immunoreactivity occurred; however, in two remote regions: the ventral premotor hand representation and the M1 hindlimb representation. Neurons in these representations were previously shown to undergo significant increases in VEGF protein immunoreactivity, and comparison of the two data sets showed a significant correlation between levels of VEGF and VEGFR-2 immunoreactivity. Thus, while remote areas undergo a molecular response to the infarct, we hypothesize that there is a delay in the initiation of the response, which ultimately may increase the 'window of opportunity' for neuroprotective interventions in the intact cortex.
Journal of Cerebral Blood Flow & Metabolism 04/2008; 28(3):612-20. · 5.01 Impact Factor
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ABSTRACT: This study describes the pattern of interhemispheric connections of the ventral premotor cortex (PMv) distal forelimb representation (DFL) in squirrel monkeys. Our objectives were to describe qualitatively and quantitatively the connections of PMv with contralateral cortical areas. Intracortical microstimulation techniques (ICMS) guided the injection of the neuronal tract tracers biotinylated dextran amine or Fast blue into PMv DFL. We classified the interhemispheric connections of PMv into three groups. Major connections were found in the contralateral PMv and supplementary motor area (SMA). Intermediate interhemispheric connections were found in the rostral portion of the primary motor cortex, the frontal area immediately rostral and ventral to PMv (FR), cingulate motor areas (CMAs), and dorsal premotor cortex (PMd). Minor connections were found inconsistently across cases in the anterior operculum (AO), posterior operculum/inferior parietal cortex (PO/IP), and posterior parietal cortex (PP), areas that consistently show connections with PMv in the ipsilateral hemisphere. Within-case comparisons revealed that the percentage of PMv connections with contralateral SMA and PMd are higher than the percentage of PMv connections with these areas in the ipsilateral hemisphere; percentages of PMv connections with contralateral M1 rostral, FR, AO, and the primary somatosensory cortex are lower than percentages of PMv connections with these areas in the ipsilateral hemisphere. These studies increase our knowledge of the pattern of interhemispheric connection of PMv. They help to provide an anatomical foundation for understanding PMv's role in motor control of the hand and interhemispheric interactions that may underlie the coordination of bimanual movements.
The Journal of Comparative Neurology 01/2008; 505(6):701-15. · 3.81 Impact Factor
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Ann M Stowe,
Erik J Plautz,
Phuong Nguyen, Shawn B Frost,
Ines Eisner-Janowicz,
Scott Barbay,
Numa Dancause,
Anirban Sensarma,
Michael D Taylor,
Elena V Zoubina,
Randolph J Nudo
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ABSTRACT: Clinical and experimental data support a role for the intact cortex in recovery of function after stroke, particularly ipsilesional areas interconnected to the infarct. There is, however, little understanding of molecular events in the intact cortex, as most studies focus on the infarct and peri-infarct regions. This study investigated neuronal immunoreactivity for hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2) in remote cortical areas 3 days after a focal ischemic infarct, as both HIF-1α and VEGFR-2 have been implicated in peri-infarct neuroprotection. For this study, intracortical microstimulation techniques defined primary motor (M1) and premotor areas in squirrel monkeys (genus Saimiri). An infarct was induced in the M1 hand representation, and immunohistochemical techniques identified neurons, HIF-1α and VEGFR-2. Stereologic techniques quantified the total neuronal populations and the neurons immunoreactive for HIF-1α or VEGFR-2. The results indicate that HIF-1α upregulation is confined to the infarct and peri-infarct regions. Increases in VEGFR-2 immunoreactivity occurred; however, in two remote regions: the ventral premotor hand representation and the M1 hindlimb representation. Neurons in these representations were previously shown to undergo significant increases in VEGF protein immunoreactivity, and comparison of the two data sets showed a significant correlation between levels of VEGF and VEGFR-2 immunoreactivity. Thus, while remote areas undergo a molecular response to the infarct, we hypothesize that there is a delay in the initiation of the response, which ultimately may increase the ‘window of opportunity’ for neuroprotective interventions in the intact cortex.Keywords: VEGF (vascular endothelial growth factor), VEGF receptor-2 (VEGFR-2), HIF-1α (hypoxia inducible factor-1α), stroke, neuron, stereology
Journal of Cerebral Blood Flow & Metabolism 09/2007; 28(3):612-620. · 5.01 Impact Factor
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ABSTRACT: Vascular endothelial growth factor (VEGF) is thought to contribute to both neuroprotection and angiogenesis after stroke. While increased expression of VEGF has been demonstrated in animal models after experimental ischemia, these studies have focused almost exclusively on the infarct and peri-infarct regions. The present study investigated the association of VEGF to neurons in remote cortical areas at three days after an infarct in primary motor cortex (M1). Although these remote areas are outside of the direct influence of the ischemic injury, remote plasticity has been implicated in recovery of function. For this study, intracortical microstimulation techniques identified primary and premotor cortical areas in a non-human primate. A focal ischemic infarct was induced in the M1 hand representation, and neurons and VEGF protein were identified using immunohistochemical procedures. Stereological techniques quantitatively assessed neuronal-VEGF association in the infarct and peri-infarct regions, M1 hindlimb, M1 orofacial, and ventral premotor hand representations, as well as non-motor control regions. The results indicate that VEGF protein significantly increased association to neurons in specific remote cortical areas outside of the infarct and peri-infarct regions. The increased association of VEGF to neurons was restricted to cortical areas that are functionally and/or behaviorally related to the area of infarct. There was no significant increase in M1 orofacial region or in non-motor control regions. We hypothesize that enhancement of neuronal VEGF in these functionally related remote cortical areas may be involved in recovery of function after stroke, through either neuroprotection or the induction of remote angiogenesis.
Journal of Cerebral Blood Flow & Metabolism 02/2007; 27(1):76-85. · 5.01 Impact Factor
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ABSTRACT: There is growing interest in the use of D-amphetamine (D-AMPH) as a pharmacological treatment to supplement rehabilitative therapy following stroke. Based on the success of earlier animal models, several clinical studies have demonstrated beneficial effects of applying physical rehabilitation while stroke patients are under the influence of D-AMPH. To begin to understand the neural mechanisms underlying this promising adjuvant therapy, the authors examined the effects of a single pairing of D-AMPH and rehabilitative training on motor performance after cortical infarct in squirrel monkeys.
Microelectrode stimulation techniques were used to delineate hand movement areas in the primary motor cortex prior to delivering a unilateral infarct to the complete hand representation. Postinfarct recovery was assessed for 3 groups of monkeys: D-AMPH + training, saline + training, and spontaneous recovery (SR). Postinfarct training groups received 14 consecutive days of motor skill training on a reach and retrieval task. A single injection of D-AMPH (0.25 mg/kg) or saline was given only on the 1st day of training (postinfarct day 10). Monkeys in the SR group had only minimal exposure to the training task once per week to monitor recovery.
The results show that a single coupling of D-AMPH + training initiated 10 days after cortical infarct facilitated the rate of recovery and improved performance (68% improvement from 1st day of training) beyond the level achieved by the monkeys in the saline + training group (27% improved from 1st day of training).
D-AMPH is a potent modulator of behavioral recovery following an ischemic infarct in nonhuman primates.
Neurorehabilitation and neural repair 01/2007; 20(4):455-8. · 4.49 Impact Factor
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ABSTRACT: After a cortical lesion, cortical areas distant from the site of injury are known to undergo physiological and anatomical changes. However, the mechanisms through which reorganization of distant cortical areas is initiated are poorly understood. In a previous publication, we showed that the ventral premotor cortex (PMv) undergoes physiological reorganization after a lesion destroying the majority of the primary motor cortex (M1) distal forelimb representation (DFL). After large lesions destroying >50% of the M1 DFL, the PMv DFL invariably increased in size, and the amount of the increase was positively correlated with the size of lesion. To determine whether lesions destroying <50% of the M1 DFL followed a similar trajectory, we documented PMv reorganization using intracortical microstimulation techniques after small, ischemic lesions targeting subregions within the M1 DFL. In contrast to earlier results, lesions resulted in a reduction of the PMv DFL regardless of their location. Further, because recent anatomical findings suggest a segregation of PMv connectivity with M1, we examined two lesion characteristics that may drive alterations in PMv physiological reorganization: location of the lesion with respect to PMv connectivity and relative size of the lesion. The results suggest that after a lesion in the M1 DFL, the induction of representational plasticity in PMv, as evaluated using intracortical microstimulation, is related more to the size of the lesion than to the disruption of its intracortical connections.
Journal of Neurophysiology 12/2006; 96(6):3506-11. · 3.32 Impact Factor
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ABSTRACT: This study was undertaken to determine the topographic organization of connections between the forelimb representations of the ventral premotor cortex (PMv) and the primary motor cortex (M1). Intracortical microstimulation techniques were used in three experimentally naive squirrel monkeys to delineate the M1 and PMv forelimb representations in the hemisphere contralateral to the dominant hand. Small amounts of biotinylated dextran amine (BDA) were then injected in the PMv distal forelimb representation. Following tangential sectioning, the location of the injection core in PMv and BDA-labeled cell bodies and synaptic boutons in M1 were documented in relation to functional topography. Whereas the injection core was mainly located within the distal forelimb representation in PMv, BDA-labeled cell bodies and terminals were distributed over comparable proportions of proximal and distal forelimb representations in M1. These results suggest that neuronal populations within PMv send topographically divergent outputs to M1 and receive topographically convergent inputs from M1. Finally, we found that PMv projections to M1 were not evenly distributed but rather were directed consistently to three domains within the rostro-lateral portion of M1. To our knowledge, this is the first description of such a consistent clustering of PMv terminals within M1.
Cerebral Cortex 09/2006; 16(8):1057-68. · 6.54 Impact Factor
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ABSTRACT: In this study stereotaxic injections of the vasoconstrictive peptide endothelin-1 (ET-1) were used to create infarcts in the white matter of the internal capsule underlying sensorimotor cortex in rats. Resulting deficits were assessed using established sensorimotor tests conducted on each rat before and after the ET-1-induced infarct. After a 14-day survival period, histological examination revealed tissue necrosis and demyelination in the infarcted white matter of ET-1-injected rats, but not saline-injected control rats. Infarcts resulted in measurable sensorimotor deficits in rats that received ET-1 injections. The same sensorimotor tests showed no deficits in surgical-control rats. The present model of white matter infarct should be valuable in examining the underlying mechanisms of subcortical ischemic stroke and to evaluate potential therapeutic interventions.
Behavioural Brain Research 06/2006; 169(2):206-11. · 3.42 Impact Factor
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ABSTRACT: The present study describes the pattern of connections of the ventral premotor cortex (PMv) with various cortical regions of the ipsilateral hemisphere in adult squirrel monkeys. Particularly, we 1) quantified the proportion of inputs and outputs that the PMv distal forelimb representation shares with other areas in the ipsilateral cortex and 2) defined the pattern of PMv connections with respect to the location of the distal forelimb representation in primary motor cortex (M1), primary somatosensory cortex (S1), and supplementary motor area (SMA). Intracortical microstimulation techniques (ICMS) were used in four experimentally naïve monkeys to identify M1, PMv, and SMA forelimb movement representations. Multiunit recording techniques and myelin staining were used to identify the S1 hand representation. Then, biotinylated dextran amine (BDA; 10,000 MW) was injected in the center of the PMv distal forelimb representation. After tangential sectioning, the distribution of BDA-labeled cell bodies and terminal boutons was documented. In M1, labeling followed a rostrolateral pattern, largely leaving the caudomedial M1 unlabeled. Quantification of somata and terminals showed that two areas share major connections with PMv: M1 and frontal areas immediately rostral to PMv, designated as frontal rostral area (FR). Connections with this latter region have not been described previously. Moderate connections were found with PMd, SMA, anterior operculum, and posterior operculum/inferior parietal area. Minor connections were found with diverse areas of the precentral and parietal cortex, including S1. No statistical difference between the proportions of inputs and outputs for any location was observed, supporting the reciprocity of PMv intracortical connections.
The Journal of Comparative Neurology 05/2006; 495(4):374-90. · 3.81 Impact Factor
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ABSTRACT: A focal injury within the cerebral cortex results in functional reorganization within the spared cortex through time-dependent metabolic and physiological reactions. Physiological changes are also associated with specific post-injury behavioral experiences. Knowing how these factors interact can be beneficial in planning rehabilitative intervention after a stroke. The purpose of this study was to assess the functional impact of delaying the rehabilitative behavioral experience upon movement representations within the primary motor cortex (M1) in an established nonhuman primate, ischemic infarct model. Five adult squirrel monkeys were trained on a motor-skill task prior to and 1 month after an experimental ischemic infarct was induced in M1. Movement representations of the hand were derived within M1 using standard electrophysiological procedures prior to the infarct and again one and two months after the infarct. The results of this study show that even though recovery of motor skills was similar to that of a previous study in squirrel monkeys after early training, unlike early training, delayed training did not result in maintenance of the spared hand representation within the M1 peri-infarct hand area. Instead, delaying training resulted in a large decrease in spared hand representation during the spontaneous recovery period that persisted following the delayed training. In addition, delayed training resulted in an increase of simultaneously evoked movements that are typically independent. These results indicate that post-injury behavioral experience, such as motor skill training, may modulate peri-infarct cortical plasticity in different ways in the acute versus chronic stages following stroke.
Experimental Brain Research 03/2006; 169(1):106-16. · 2.39 Impact Factor
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ABSTRACT: Previously, we showed that the ventral premotor cortex (PMv) underwent neurophysiological remodeling after injury to the primary motor cortex (M1). In the present study, we examined cortical connections of PMv after such lesions. The neuroanatomical tract tracer biotinylated dextran amine was injected into the PMv hand area at least 5 months after ischemic injury to the M1 hand area. Comparison of labeling patterns between experimental and control animals demonstrated extensive proliferation of novel PMv terminal fields and the appearance of retrogradely labeled cell bodies within area 1/2 of the primary somatosensory cortex after M1 injury. Furthermore, evidence was found for alterations in the trajectory of PMv intracortical axons near the site of the lesion. The results suggest that M1 injury results in axonal sprouting near the ischemic injury and the establishment of novel connections within a distant target. These results support the hypothesis that, after a cortical injury, such as occurs after stroke, cortical areas distant from the injury undergo major neuroanatomical reorganization. Our results reveal an extraordinary anatomical rewiring capacity in the adult CNS after injury that may potentially play a role in recovery.
Journal of Neuroscience 12/2005; 25(44):10167-79. · 7.11 Impact Factor
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ABSTRACT: Primary motor cortex (M1) has traditionally been considered a motor structure. Although neurophysiologic studies have demonstrated that M1 is also influenced by somatosensory inputs (cutaneous and proprioceptive), the behavioral significance of these inputs has yet to be fully defined in primates. The present study describes differential sensory-related deficits after small ischemic lesions in either the rostral or caudal subregion of the M1 hand area in a nonhuman primate. Squirrel monkeys retrieved food pellets out of different sized wells drilled into a Plexiglas board. Before the lesion, monkeys retrieved pellets by directing the hand to the well, inserting fingers directly into it, and extracting the pellet. After a lesion to the rostral portion of M1, monkeys frequently failed to direct the hand accurately to the well. Instead, fingers contacted the surface of the board outside the well before entering the well. These aiming errors are consistent with both the large amount of proximal motor outputs and the predominant proprioceptive inputs of rostral M1. Overall, these aiming errors are suggestive of dysfunctional processing of proprioceptive information or the failure to integrate proprioceptive information with motor commands. In contrast, after a lesion to the caudal portion of M1, monkeys frequently examined their palm visually for the presence of the pellet after an attempted retrieval. These errors are consistent with both the large amount of distal motor outputs and the predominant cutaneous inputs of caudal M1. Thus these errors are suggestive of a deficit in processing of cutaneous information or the failure to integrate cutaneous information with motor commands. Rostral and caudal M1 lesions result in different deficits in sensory-dependent motor control that appear to correlate with broad segregation of motor outputs and previously described sensory inputs of M1.
Journal of Neurophysiology 09/2005; 94(2):1312-24. · 3.32 Impact Factor
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ABSTRACT: Stroke is often characterized by incomplete recovery and chronic motor impairments. A nonhuman primate model of cortical ischemia was used to evaluate the feasibility of using device-assisted cortical stimulation combined with rehabilitative training to enhance behavioral recovery and cortical plasticity. Following pre-infarct training on a unimanual motor task, maps of movement representations in primary motor cortex were derived. Then, an ischemic infarct was produced which destroyed the hand representation. Several weeks later, a second cortical map was derived to guide implantation of a surface electrode over peri-infarct motor cortex. After several months of spontaneous recovery, monkeys underwent subthreshold electrical stimulation combined with rehabilitative training for several weeks. Post-therapy behavioral performance was tracked for several additional months. A third cortical map was derived several weeks post-therapy to examine changes in motor representations. Monkeys showed significant improvements in motor performance (success, speed, and efficiency) following therapy, which persisted for several months. Cortical mapping revealed large-scale emergence of new hand representations in peri-infarct motor cortex, primarily in cortical tissue underlying the electrode. Results support the feasibility of using a therapy approach combining peri-infarct electrical stimulation with rehabilitative training to alleviate chronic motor deficits and promote recovery from cortical ischemic injury.
Neurological Research 01/2004; 25(8):801-10. · 1.52 Impact Factor
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ABSTRACT: Nonhuman primate models of poststroke recovery have become increasingly rare primarily due to high purchase and maintenance costs and limited availability of nonhuman primate species. Despite this obstacle, nonhuman primate models may offer important advantages over rodent models for understanding many of the brain's mechanisms for self-repair due to greater similarity in cortical organization to humans. Since the mid-1990s, surgical, neurophysiological, and neuroanatomical methods have been developed to understand structural and functional remodeling of the cerebral cortex after an ischemic event, such as occurs in stroke. These methods require long surgical procedures and entail constant physiological monitoring. With careful attention to intraoperative and postsurgical monitoring, these procedures can be repeated multiple times in individual monkeys without untoward events. This model provides a statistically powerful approach for tracking brain plasticity in the ensuing weeks and months after a stroke-like injury, reducing the number of animals required for individual experiments. This methodology is described in detail, and many of the resulting findings that are relevant for understanding stroke recovery and the effects of rehabilitative and pharmacotherapeutic interventions are summarized.
ILAR journal / National Research Council, Institute of Laboratory Animal Resources 02/2003; 44(2):161-74. · 2.33 Impact Factor
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ABSTRACT: To examine the potential early stages in the evolution of sensorimotor cortex, electrophysiological studies were conducted in the primitive South American marsupial opossum, Monodelphis domestica. Somatosensory maps derived from multiunit microelectrode recordings revealed a complete somatosensory representation of the contralateral body surface within a large region of midrostral cortex (primary somatosensory cortex, or S1). A large proportion (∼51%) of S1 was devoted to representation of the glaborous snout, mystacial vibrissae, lower jaw, and oral cavity (the rostrum). A second representation, the second somatosensory area (or S2), was found adjacent and caudolateral to S1 as a mirror image reversed along the representation of the glabrous snout. A reversal of somatotopic order and an enlargement of receptive fields marked the transition from S1 to S2. Mapping of excitable cortex was conducted by using intracortical microstimulation (ICMS) techniques, as well as low-impedance depth stimulation and bipolar surface stimulation. In all three procedures, electrical stimulation resulted in movements confined strictly to the face. Specifically, at virtually all sites from which movements could be evoked, stimulation resulted in only vibrissae movement. ICMS-evoked vibrissae movements typically occurred at sites within S1 with receptive fields of the mystacial vibrissae, lower jaw, and glaborous snout. Results were similar using low-impedance depth stimulation and bipolar surface stimulation techniques except that the motor response maps were generally larger in area. There was no evidence of a motor representation rostral to S1. Examination of the cytoarchitecture in this cortical region (reminiscent of typical mammalian somatosensory cortex) and the high levels of stimulation needed for vibrissae movement suggest that the parietal neocortex of Monodelphis is representative of a primitive sensorimotor condition. It possesses a complete S1 representation with an incomplete motor component overlapping the S1 representation of the face. It contains no primary motor representation. Completion of the motor representations within S1 (trunk, limbs, tail) as well as the emergence of a primary motor cortex rostral to S1 may have occurred relatively late in mammalian phylogeny. J. Comp. Neurol. 421:29–51, 2000. © 2000 Wiley-Liss, Inc.
The Journal of Comparative Neurology 05/2000; 421(1):29 - 51. · 3.81 Impact Factor
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ABSTRACT: Small lesions to rostral versus caudal portions of the hand representation in the primary motor cortex (M1) produce different behavioral deficits. The goal of the present study was to determine if rehabilitative training has similar effects on functional topography of the spared M1 after rostral versus previously reported caudal M1 lesions.
Following a lesion to the rostral M1 hand area, monkeys were trained for 1 h/day for 30 days to retrieve food pellets from small wells using their impaired hand. Electrophysiological maps of the M1 were derived in anesthetized monkeys before infarct and after rehabilitative training using intracortical microstimulation.
After a lesion to the rostral M1 and rehabilitative training, the size of the spared hand representation decreased 1.2%. This change is not statistically different from the 9% increase seen after caudal M1 lesion and rehabilitative training (P > 0.2).
Postlesion training spares peri-infarct hand area regardless of whether the lesion is in the rostral or caudal M1.
Neurorehabilitation and neural repair 21(1):51-61. · 4.49 Impact Factor
