Sensory processing in Huntington's disease.
An intriguing electrophysiological feature of patients with Huntington's disease (HD) is the delayed latency and decreased amplitude of somatosensory long-latency evoked potentials (LLeps). We investigated whether such dysfunction was associated with delayed conscious perception of the sensory stimulus.



Sixteen HD patients and 16 control subjects faced a computer screen showing the Libet's clock (Libet et al., 1983). In Rest trials, subjects had to memorize the position of the clock handle at perception of either electrical or thermal stimuli (AW). In React, additionally, they were asked to make a fist with their right hand, in a simple reaction time task (SRT). LLseps were recorded from Cz in both conditions.



LLeps negative peak latency (N2) and SRT were abnormally delayed in patients in all conditions. AW was only abnormally prolonged in the React condition but the time difference between AW and the negative peak of the LLeps was not different in the two groups. There was a significant negative correlation between SRT and AW or LLeps amplitude in patients but not in healthy subjects.



Our HD patients did not show abnormalities in conscious perception of sensory stimuli but their LLeps abnormalities were more marked when they had to react. This is compatible with failure to detect stimulus salience rather than with a cognitive defect.



HD patients at early stages of the disease have preserved subjective perception of sensation but faulty sensorimotor integration.
EMG Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain; Center for Neural Science (CNS), New York University (NYU), USA. Electronic address: ana.mirallave@gmail.com.
Ana
A
Mirallave
EMG Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Merche
M
Morales
EMG Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Christopher
C
Cabib
Movement Disorders Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Esteban J
EJ
Muñoz
Movement Disorders Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Pilar
P
Santacruz
Neurophysiology Lab, Department of Physiological Sciences I, Medical School, Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Xavier
X
Gasull
EMG Unit, Neurology Department, Hospital Clinic, Facultat de Medicina, University of Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Spain.
Josep
J
Valls-Sole
D000328:Adult; D016022:Case-Control Studies; D003071:Cognition; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010465:Perception; D011930:Reaction Time
Conscious perception; Evoked potentials; Huntington’s disease; Reaction time; Sensory processing