Recruitment gain of spinal motor neuron pools in cat and human.

The output from a motor nucleus is determined by the synaptic input to the motor neurons and their intrinsic properties. Here, we explore whether the source of synaptic inputs to the motor neurons (cats) and the age or post-stroke conditions (humans) may change the recruitment gain of the motor neuron pool. In cats, the size of Ia EPSPs in triceps surae motor neurons (input) and monosynaptic reflexes (MSRs; output) was recorded in the soleus and medial gastrocnemius motor nerves following graded stimulation of dorsal roots.

Impact of subthalamic stimulation and medication on proximal and distal bradykinesia in Parkinson's disease.

Objective: To evaluate the usefulness of a new instrument for bedside testing of proximal arm and distal finger tapping performance in patients with Parkinson's disease (PD).

Methods: Twenty healthy controls and 25 PD patients with subthalamic nucleus deep brain stimulation were investigated in different treatment conditions using three different tapping paradigms: (1) the standard tapping task of the CAPSIT-PD-protocol; (2) alternate pressing of two buttons on the new board by moving the arm at the elbow and shoulder (proximal tapping), and (3) alternate pressing of two closely collocated buttons on the new board by moving only the index finger (distal tapping) for 30 s.

Results: The new tapping board was as sensitive as the standard board to distinguish untreated PD patients from controls.

Kinematic analysis of thalamic versus subthalamic neurostimulation in postural and intention tremor.

Deep brain stimulation of the thalamus (thalamic DBS) is an established therapy for medically intractable essential tremor and tremor caused by multiple sclerosis. In both disorders, motor disability results from complex interaction between kinetic tremor and accompanying ataxia with voluntary movements. In clinical studies, the efficacy of thalamic DBS has been thoroughly assessed.

Eye-hand coordination in essential tremor.

Patients with essential tremor (ET) or with cerebellar lesions have in common oculomotor abnormalities, with the exception of saccadic eye movements, which do not seem to be involved in ET. Since grasping is prolonged in ET and might be related to saccadic dysmetria, we tested whether simultaneous hand pointing could unmask it. Twelve ET patients and 14 controls performed saccades with and without simultaneous pointing movements to the same targets, and with and without a gap between the disappearance of the fixation point and the appearance of the target.