This project comprises three sets of physiological studies - testing eight specific hypotheses - that will contribute new knowledge on proprioception and motor control in a genetic disorder that affects specific components of the sensory nervous system.

I: To investigate the neurophysiological basis for disturbed motor control in Hereditary sensory and autonomic neuropathy (HSAN) III II: To investigate the effects of enhancing cutaneous feedback on motor control in HSAN III III: To investigate the cortical representation of proprioceptive inputs in HSAN III

HSAN III patients (n=15) and healthy control subjects (n=15) will lay supine on an MRI bed and a tungsten microelectrode inserted percutaneously into a muscle or cutaneous fascicle of the right common peroneal nerve at the fibular head, according to standard techniques employed by Prof Macefield. Neural activity will be acquired, RMS-processed (200 ms) and analysed on computer. The subject's head will be tightly enclosed in a standard clinical 32-channel SENSE head coil and headphones will be provided to minimize noise and to allow communication with the subject. The subject will be placed in the bore of a 3T whole-body scanner for 60-90 minutes.

Inclusion Criteria:

• Confirmed genetic diagnosis of HSAN III will be recruited from the Dysautonomia Center at NYU

Exclusion Criteria:

• homeless
• active drug or alcohol dependence
• evidence of neurological disorder or diabetes
• exposure to neurotoxic drugs that in the investigator's opinion may compromise results
• Pregnant women