Cortical reintegration after facial allotransplantation.

Neural plasticity of the brain or its ability to reorganize following injury has likely coincided with the successful clinical correction of severe deformity by facial transplantation since 2005. In this study, we present the cortical reintegration outcomes following syngeneic hemifacial vascularized composite allograft (VCA) in a small animal model. Specifically, changes in the topographic organization and unit response properties of the rodent whisker-barrel somatosensory system were assessed following hemifacial VCA.

Effect of whisker geometry on contact force produced by vibrissae moving at different velocities.

Rats and mice are able to perform a variety of subtle tactile discriminations with their mystacial vibrissae. Increasingly, the design and interpretation of neurophysiological and behavioral studies are inspired by and linked to a more precise understanding of the detailed physical properties of the whiskers and their associated hair follicles. Here we used a piezoelectric sensor (bimorph) to examine how contact forces are influenced by the geometry of individual whisker hairs.

Response properties of whisker-associated primary afferent neurons following infraorbital nerve transection with microsurgical repair in adult rats.

The rodent whisker/trigeminal system, characterized by high spatial and temporal resolution, provides an experimental model for developing new therapies for improving sensory functions of damaged peripheral nerves. Here, we use controlled whisker stimulation and single-unit recordings of trigeminal ganglion cells to examine in detail the nature and time course of functional recovery of mechanoreceptive afferents following nerve transection with microsurgical repair of the infraorbital nerve (ION) branch of the trigeminal nerve in adult rats. Response measures include rapid vs.

The synergistic effect of treadmill running on stem-cell transplantation to heal injured skeletal muscle.

Muscle-derived stem-cell (MDSC) transplantation presents a promising method for the treatment of muscle injuries. This study investigated the ability of exercise to enhance MDSC transplantation into the injured muscle. Mice were divided into four groups: contusion + phosphate-buffered saline (C + PBS; n = 14 muscles), C + MDSC transplantation (n = 12 muscles), C + PBS + treadmill running (C + PBS + TM; n = 17 muscles), and C + MDSC + TM (n = 13 muscles).

A model for functional recovery and cortical reintegration after hemifacial composite tissue allotransplantation.

Background: The ability to achieve optimal functional recovery is important in both face and hand transplantation. The purpose of this study was to develop a functional rat hemifacial transplant model optimal for studying both functional outcome and cortical reintegration in composite tissue allotransplantation.

Methods: Five syngeneic transplants with motor and sensory nerve appositions (group 1) and five syngeneic transplants without nerve appositions (group 2) were performed.

Motor modulation of afferent somatosensory circuits.

A prominent feature of thalamocortical circuitry in sensory systems is the extensive and highly organized feedback projection from the cortex to the thalamic neurons that provide stimulus-specific input to the cortex. In lightly sedated rats, we found that focal enhancement of motor cortex activity facilitated sensory-evoked responses of topographically aligned neurons in primary somatosensory cortex, including antidromically identified corticothalamic cells; similar effects were observed in ventral posterior medial thalamus (VPm). In behaving rats, thalamic responses were normally smaller during whisking but larger when signal transmission in brainstem trigeminal nuclei was bypassed or altered.

Thalamocortical conduction times and stimulus-evoked responses in the rat whisker-to-barrel system.

Studies of the rodent whisker system indicate that somatosensory cortical circuitry operates at a millisecond timescale to transform sensory afferent signals from the thalamus. We measured axon conduction times and whisker-evoked responses of 48 thalamocortical (TC) neurons in the rat whisker-to-barrel pathway. Conduction times were derived from spike-triggered averages of local field potentials evoked in layer 4 cortical whisker-related barrels by the spontaneous firing of individual topographically aligned neurons in the ventral posterior medial thalamus.

Texture discrimination and unit recordings in the rat whisker/barrel system.

We have developed a semi-automated technique for acquiring neurophysiological data during whisker-based tactile discriminative behavior. Water-deprived, blindfolded rats are tethered by means of a harness vest that permits them to contact a rough (250 micrometer grooves) or smooth discriminandum with only their vibrissae. Discriminanda are mounted on a motor-driven carousel, and the rat indicates its choice (rough, smooth) by licking either a right or left water port located near the carousel.

Voluntary upper-extremity movements in patients with unilateral peripheral vestibular hypofunction.

Background And Purpose: People with peripheral vestibular pathology demonstrate motor impairments when responding and adapting to postural platform perturbations and during performance of sit-to-stand and locomotor tasks. This study investigated the influence of unilateral peripheral vestibular hypofunction on voluntary arm movement.

Subjects And Methods: Subjects without known neurological impairments and subjects with vestibular impairments performed 3 voluntary arm movements: an overhead reach to a target, a sideward reach to a target, and a forward flexion movement through 90 degrees.