This study will examine and compare how the brain controls the timing of movement in healthy
volunteers and in people with schizophrenia. Previous experiments have shown that when
people are asked to look at a clock and report the time they first decide to make a
movement, they report times later than the first brain waves associated with movement
appear. When they are asked to report the time they first initiate the movement, they report
times before the muscles actually begin to move. The study may help determine how the sense
of willing and initiating an action is altered in schizophrenic patients, and how people may
feel more or less "in control" of their movements.
Normal volunteers and patients with schizophrenia between 18 and 65 years of age may be
eligible for this study. Control subjects must not have any neurological or psychological
disorders, and schizophrenia patients must not have any other neurological disorders.
All participants will have a medical history, physical examination, and a test to determine
their level of attention. Schizophrenia patients will be interviewed about their symptoms
and complete psychiatric rating scales. In addition, all participants will undergo the
Participants look at a clock on a computer screen whose hands revolves around the clock
fast. While they look at the clock, they are given small, non-painful electric shocks and
are asked to say when they receive the shocks, according to the clock. The shocks are
repeated 40 times.
Participants are asked to lift their arm up off a table repeatedly, at random times, while
they look at the computer clock. This exercise is repeated a total of 80 times. Of these 80
times, participants are asked 10 times in a row to say the time they first had the desire to
move their arm, and then 10 times in a row the time they first felt that they were moving
Electroencephalography (EEG) and Electromyography (EMG)
Participants undergo EEG and EMG during the electric shock and arm movement experiments to
measure electrical activity of the brain (EEG) and of the muscles (EMG). For EEG, electrodes
(small metal discs) are placed on the scalp with a cap, paste, or glue-like substance and
the brain waves are recorded. For EMG, electrodes are taped to the skin over the muscle.
The purpose of this study is to determine how the subjective sense of willing and initiating
an action is altered in schizophrenic patients. One proposed explanation for characteristic
symptoms of schizophrenia ("passivity phenomena") is a defect in the forward model of
movement that the brain receives as the motor signal is generated. We propose to examine
this forward model using Libet's paradigm, in which normal subjects gave evidence for a
forward model in their anticipatory reports of initiation of movement. We intend to
determine the times associated with willing (W), initiating (M), and
electroencephalographic/electromyographic (EEG/EMG) measures of movement.
We intend to study adult patients with a Diagnostic and Statistical Manual of Mental
Disorders diagnosis of schizophrenia. These patients provide a unique population for this
study because they often do not have the sense that they direct their own movement or author
their own thoughts (passivity phenomena). Studies have shown that schizophrenics have
movement-related cortical potentials on EEG, but it is not known when the subjective sense
of initiating movement occurs for these patients. As the order of mental events in time has
been shown to contribute to the sense of agency, it is important to know how the timing of
voluntary movement is altered in schizophrenia.
We will ask patients to look at a fast-rotating clock on a computer screen and note when
their movements were willed, instigated by an external agent if they have such delusions,
and were initiated. Patients will also report the time of a somatosensory stimulus. Surface
EMG will determine the time of actual movement, and EEG will record brain potentials
associated with movement. Eligible patients with schizophrenia and passivity phenomena will
be recruited from the Clinical Brain Disorders Branch, NIMH.
The primary outcome measure of this study is the absence of time W in some schizophrenics,
the latency of W in other schizophrenics compared to normal subjects, and the latency of M
in schizophrenics compared to normals. Any effect of medication status or symptoms on
performance in the study will be considered exploratory data.
- INCLUSION CRITERIA:
Experimental subjects will be patients with DSM-IV diagnosis of schizophrenia who have
volunteered to participate in the clinical research unit of the Clinical Brain Disorders
Branch, NIMH. In addition, outpatients with DSM-IV diagnosis of schizophrenia who
participate in outpatient research through the CBDB will be included. All patients will
have received the diagnosis of schizophrenia by means of the Structured Clinical Interview
for DSM-IV (SCID) with three psychiatrists reaching a consensus diagnosis. Patients on the
clinical research unit must meet rigorous criteria in order to participate in research.
Exclusionary criteria include history of traumatic brain injury, known comorbid
neurological disorders, including epilepsy, history of drug and alcohol abuse, etc. All
patients will have undergone a comprehensive battery of neuropsychological tests,
including Wide Range Achievement Test- Reading (often to be a good indicator of premorbid
intelligence), a short version of Wechsler Adult Intelligence Scale (WAIS-R), Wechsler
Memory Scales (WMS-R), Trails A and B, tests of attention and executive function,
including the continuous performance test (CPT), Wisconsin Card Sort (WISC), the N-Back
test of working memory. Patients with psychiatric diseases other than schizophrenia that
are not currently active and symptomatic will be included.
All patients in the study will have schizophrenia. However, at the time of testing,
patients will be administered clinical rating scales (i.e., Brief Psychotic Rating Scale
(BPRS), appropriate sections of the SCID and the Yale Hallucination Phenomenology
Assessment (YHPA)) to determine the presence of passivity phenomena.
Twenty-six normal controls will be included; controls will be screened in the NINDS
Movement Disorders Outpatient Clinic, and will have neurological and physical
examinations. They will be asked to abstain from alcohol for 24 hours before the study.
All subjects participating in the studies will have a valid Clinical Center Medical Record
All subjects will be between the ages of 18 and 65. Subjects may be male or female.
Patients younger than 18 years old or older than 65 years old will be excluded from the
A. Patients with neurological disorders will be excluded. Patients with psychiatric
disorders other than schizophrenia who are experiencing an active phase of their disorder
will be excluded.
B. Patients with a history of significant medical disorders requiring chronic treatment
with other drugs, which affect the central nervous system and cannot be stopped will be
C. Patients not capable of giving an informed consent will be excluded.