Eye Blink Response in Healthy Volunteers and Adults With Schizophrenia
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.
|Official Title:||Investigation of Brain Function During Eyeblink Responding in Normal Volunteers and Patients With Schizophrenia (A Study of Behavior and Evoked Potentials)|
|Study Start Date:||August 1999|
|Estimated Study Completion Date:||June 2010|
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.
|United States, Maryland|
|National Institutes of Health Clinical Center, 9000 Rockville Pike|
|Bethesda, Maryland, United States, 20892|