Altered eyeblink reflex conditioning in restless legs syndrome patients

McEchron, Matthew D.; Alexander, Danielle N.; Smith, Michael E.; Hoffman, Deborah L.; Podskalny, Gerald D.; Connor, James R.

doi:10.1016/j.sleep.2009.06.010

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Volume 11, Issue 3 , Pages 314-319, March 2010

Altered eyeblink reflex conditioning in restless legs syndrome patients

Matthew D. McEchron
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
- Department of Medical Education, University of Wyoming, Laramie, WY 82071, USA
- Corresponding author. Tel.: +1 307 766 2497; fax: +1 307 766 2492.
Danielle N. Alexander
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
Michael E. Smith
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
Deborah L. Hoffman
- Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
Gerald D. Podskalny
- Department of Neurology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
James R. Connor
- Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA

Received 29 January 2009; received in revised form 24 April 2009; accepted 16 June 2009.

Abstract

Background

Restless legs syndrome (RLS) is characterized by abnormal leg sensations and an uncontrollable urge to move the lower extremities during rest periods. Evidence suggests that reflex tasks that involve sensory–motor integration may be altered in RLS patients. This led us to determine if RLS patients show alterations in a sensory–motor reflex conditioning task called differential eyeblink conditioning.

Methods

RLS subjects were washed out of treatment medication for 7days prior to testing. Subjects (20 RLS and 19 Control) received 120 discrimination conditioning trials consisting of 60 CS+ trials (i.e., an auditory stimulus paired with the airpuff-US separated by a silent 900ms trace interval) and 60 CS− trials (i.e., a different auditory stimulus that was NOT paired with the US).

Results

Control subjects showed normal differential responding to the CS+ and CS−, but the RLS patients showed little or no differential responding. A post-test questionnaire provides evidence that symptomatic interference was not responsible for the eyeblink conditioning deficits in the RLS subjects, and further suggests that neurophysiological factors were responsible for these deficits.

Conclusions

Together these results suggest that deficits in eyeblink conditioning are related to the pathophysiology of RLS. The eyeblink conditioning test may also be useful for supporting a clinical diagnosis or treatment strategy for RLS.

Keywords: Sensory, Motor, Eyeblink, RLS, Reflex, Conditioning, Electrophysiology