Omar A. Gharbawie

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The nodes of a parietal-frontal pathway that mediates grasping in primates are in anterior intraparietal area (AIP) and ventral premotor cortex (PMv). Nevertheless, multiple somatosensory and motor representations of the hand, in parietal and frontal cortex, respectively, suggest that additional pathways remain unrealized. We explored this possibility in(More)
The failure of injured axons to regenerate following spinal cord injury deprives brain neurons of their normal sources of activation. These injuries also result in the reorganization of affected areas of the central nervous system that is thought to drive both the ensuing recovery of function and the formation of maladaptive neuronal circuitry. Better(More)
The effect of the premature commitment of neurons to exuberant growth by nicotine on concurrent and subsequent learning is unknown and was the focus of the present study. Animals were trained on a tray reaching for food task (where lots of pieces of chicken feed were available) for 3 weeks before they received two daily injections of nicotine (0.3 mg/kg) or(More)
The classical approach to investigating brain contributions to behavior has been to localize function to a region. In clinical investigations, however, injury is frequently multifocal, raising the question of how individual brain regions contribute to a resulting behavioral syndrome. For example, middle cerebral artery (MCA) ischemia in humans can(More)
When given a locomotor/exploratory test in the laboratory, rats form one or more home bases, operationally defined as places where they spend a disproportionate period of their time and from which they make excursions. Because exploratory tests in the laboratory necessarily restrict the animals' movements, the cause of exploration (e.g., fear, curiosity,(More)
We examined the connections of posterior parietal cortex (PPC) with motor/premotor cortex (M1/PM) and other cortical areas. Electrical stimulation (500 ms trains) delivered to microelectrode sites evoked movements of reach, defense, and grasp, from distinct zones in M1/PM and PPC, in squirrel and owl monkeys. Tracer injections into M1/PM reach, defense, and(More)
Unilateral damage to cortical areas in the frontal cortex produces sensorimotor deficits on the side contralateral to the lesion. Although there are anecdotal reports of bilateral deficits after stroke in humans and in experimental animals, little is known of the effects of unilateral lesions on the same side of the body. The objective of the present study(More)
Parietal-frontal networks in primate brains are central to mediating actions. Physiological and anatomical investigations have shown that the parietal-frontal network is consistently organized across several branches of primate evolution that include prosimian galagos, New World owl and squirrel monkeys, and Old World macaque monkeys. Electrical stimulation(More)
Middle cerebral artery (MCA) stroke in the rat produces impairments in skilled movements. The lesion damages lateral neocortex but spares primary motor cortex (M1), raising the question of the origin of skilled movement deficits. Here, the behavioral deficits of MCA stroke were identified and then M1 was examined neurophysiologically and neuroanatomically.(More)
The notion that shock or diaschisis is a distinctive stage in the recovery process following brain damage has played a formative role in the characterization of brain injury. For example, damage to the forelimb region of motor cortex results in an acute period of behavioural depression in skilled reaching and other skilled actions followed by improved(More)