Layer 5 neurons of the neocortex receive direct and relatively strong input from the thalamus. However, the intralaminar distribution of these inputs and their capacity for plasticity in adult animals are largely unknown. In slices of the primary motor cortex (M1), we simultaneously recorded from pairs of corticospinal neurons associated with control of distinct motor outputs: distal forelimb v...

Turtles use their limbs during both aquatic and terrestrial locomotion, but water and land impose dramatically different physical requirements. How must musculoskeletal function be adjusted to produce locomotion through such physically disparate habitats? We addressed this question by quantifying forelimb kinematics and muscle activity during aquatic and terrestrial locomotion in a generalized ...

The majority of terrestrial locomotion studies have focused on parasagittal motion and paid less attention to forces or movement in the frontal plane. Our previous research has shown that grizzly bears produce higher medial ground reaction forces (lateral pushing from the animal) than would be expected for an upright mammal, suggesting frontal plane movement may be an important aspect of their ...

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....

Storage and utilization of strain energy in the elastic tissues of the distal forelimb of the horse is thought to contribute to the excellent locomotory efficiency of the animal. However, the structures that facilitate elastic energy storage may also be exposed to dangerously high forces, especially at the fastest galloping speeds. In the present study, experimental gait data were combined with...

The ability of dopaminergic (DA) transplants to restore complex sensorimotor behaviors in experimental Parkinson's disease is dependent on graft survival and reinnervation and is likely to be further modified by complex functional graft-host interactions. Here, we examined the impact of hemispheric dominance and extensive testing regimes on the functional capabilities of DA transplants to resto...

We characterized the architecture, fiber type, titin isoform distribution, and collagen content of 27 portions of 22 muscles in the murine forelimb. The mouse forelimb was different from the human arm in that it had the extensor digitorum lateralis muscle and no brachioradialis muscle. Architecturally, the mouse forelimb differed from humans with regard to load bearing, having a much larger con...

Recovery of hand function following lesions in the primary motor cortex (M1) is associated with a reorganization of premotor areas in the ipsilesional hemisphere, and this reorganization depends on the size of the lesion. It is not clear how lesion size affects motor representations in the contralesional hemisphere and how the effects in the 2 hemispheres compare. Our goal was to study how lesi...

The Effect of Body Position and Forelimb Exercise on Cephalic Blood Flow • Flow through both common carotid, vertebral, and subclavian arteries was measured with "C-core" probes and square wave electromagnetic flowmeters in mongrel dogs. Exercise of the neurally isolated forelimb was simulated by electrical stimulation to obtain first clonic and then tetanic muscle contraction. Exercise was per...

Traumatic Brain Injury (TBI) is one of the largest health problems in the United States, and affects nearly 2 million people every year. The effects of TBI, including weakness and loss of coordination, can be debilitating and last years after the initial injury. Recovery of motor function is often incomplete. We have developed a method using electrical stimulation of the vagus nerve paired with...