Eye Blink Response in Healthy Volunteers and Adults With Schizophrenia
Condition: Healthy; Schizophrenia
MeSH terms: Schizophrenia
Study type: Observational

Summary: 
      The purpose of this study is to explore how the brain works during particular memory tasks in
      people with schizophrenia and healthy volunteers.

      Research has shown that patients with schizophrenia have structural and functional
      abnormalities in the hippocampus and cerebellum of their brains. These abnormalities are
      likely associated with the memory impairment experienced by these patients. Eye blink tests
      can provide information about memory acquisition involving the cerebellar and hippocampal
      regions. By altering the stimuli interval, these tests can distinguish between
      cerebellum-dependent memory associated with subliminal mnemonic encoding and
      hippocampus-dependent memory associated with conscious awareness. This study will use
      eyeblink tests to determine which type of memory is predominantly affected in schizophrenia.

      Participants in this study will be screened with a physical and psychiatric examination.
      Participants will have an electroencephalogram (EEG), an electrocardiogram (ECG), and an
      electrodermal test. Evoked potentials and magnetic resonance imaging (MRI) scans of the brain
      may also be taken.
    

Detailed description: 
      Eyeblink conditioning is a paradigm that allows the study of aspects of the neural mechanism
      of memory in humans. This paradigm has been extensively studied in animals and human beings
      and its functional neuroanatomy appears to be well understood, involving the hippocampus and
      cerebellum. The performance on this task is most likely independent of subject motivation.
      Moreover, manipulation of the intervals between conditioned and unconditioned stimuli allows
      to study subliminal forms of mnemonic encoding ("delay" task) as well as learning that is
      associated with conscious awareness ("trace" task). This makes eyeblink conditioning
      particularly suited for study in patient populations, and particularly in schizophrenia where
      motivation and attention are frequently confounding factors in the study of memory processes.

      Patients with schizophrenia have been reported to have hippocampal and possibly cerebellar
      structural and functional abnormalities, however eyeblink conditioning has been minimally
      studied in this patient population. We expect implicit forms of memory (cerebellum dependent)
      to be relatively spared as compared to declarative memory (hippocampus dependent) in
      schizophrenia.

      We would like to test the hypothesis that patients with schizophrenia have deficits in
      acquiring the trace form of the task as opposed to the delay, where we assume they would be
      unimpaired as compared to normal controls. We would also like to study heart rate and skin
      conductance changes that occur during conditioning, since patients with schizophrenia have
      showed impaired autonomic function.

      We also plan to study neurophysiological correlates of these behaviors with evoked response
      potentials (EP) and eventually functional magnetic resonance imaging (fMRI)

      We expect EPs to show significant change in relation to development of the behavioral
      response. The association of awareness of the stimulus contingency with slow cortical
      potentials on the EEG will also be of interest.
    

Keywords: Schizophrenia; Eyeblink; Evoked Potentials; Learning; Normal Volunteer; Healthy Volunteer