From studies of subhuman primates it has been assumed that functional corticospinal innervation occurs post-natally in man. We report a post-mortem morphological study of human spinal cord, and neurophysiological and behavioural studies in preterm and term neonates and infants. From morphological studies it was demonstrated that corticospinal axons reach the lower cervical spinal cord by 24 wee...

OBJECTIVE We examined how corticospinal excitability was affected by motor imagery of foot dorsiflexion and motor imagery of gait. METHODS Transcranial magnetic stimulation was applied over the primary motor cortex of 16 young healthy subjects while they performed imaginary foot dorsiflexions (Experiment I) and imaginary walking (Experiment II). Motor-evoked potentials (MEPs) were recorded fr...

OBJECTIVE We compared manual infarct definition, which is time-consuming and open to bias, with an automated abnormal tissue detection method in measuring corticospinal tract-infarct overlap volumes in chronic stroke patients to help predict motor outcome. METHODS Using diffusion tensor imaging and probabilistic tractography, 4 corticospinal tracts from the primary motor cortex, dorsal and ve...

Brain injury that results in an initial behavioural deficit is frequently followed by spontaneous recovery. The intrinsic mechanism of this functional recovery has never been fully understood. Here, we show that reorganization of the corticospinal tract induced by target-derived brain-derived neurotrophic factor is crucial for spontaneous recovery of motor function following brain injury. After...

27 This study investigated whether repetitive transcranial magnetic stimulation (TMS) delivered as 28 continuous theta burst stimulation (cTBS) to left M1 degraded selective muscle activation in the 29 contralateral and ipsilateral upper limb in healthy participants. Contralateral motor evoked 30 potentials (cMEPs) were elicited in left and right biceps brachii (BB) before either elbow flexion ...

Emerging evidence suggests that regular physical activity can impact cortical function and facilitate plasticity. In the present study, we examined how physical activity levels influence corticospinal excitability and intracortical circuitry in motor cortex following a single session of moderate intensity aerobic exercise. We aimed to determine whether exercise-induced short-term plasticity dif...

OBJECTIVE To examine the mechanisms of disuse-induced plasticity following long-term limb immobilization. METHODS We studied 9 subjects, who underwent left upper limb immobilization for unilateral wrist fractures. All subjects were examined immediately after splint removal. Cortical motor maps, resting motor threshold (RMT), motor evoked potential (MEP) latency and MEP recruitment curves were...

Repeated pairs of timed presynaptic and postsynaptic potentials cause lasting changes in efficacy of transmission at many synapses. The corticospinal tract is the major pathway controlling voluntary movement in humans, and corticospinal neurons have monosynaptic connections to motoneurons of many muscles. We hypothesized that corticospinal transmission in humans could be altered by delivering, ...

Motor cortex is a key brain center involved in motor control in rodents and other mammals, but specific intracortical mechanisms at the microcircuit level are largely unknown. Neuronal expression of hyperpolarization-activated current (I(h)) is cell class specific throughout the nervous system, but in neocortex, where pyramidal neurons are classified in various ways, a systematic pattern of exp...