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The cause of stuttering is unknown. Failure to develop left-hemispheric dominance for speech is a long-standing theory although others implicated the motor system more broadly, often postulating hyperactivity of the right (language nondominant) cerebral hemisphere. As knowledge of motor circuitry has advanced, theories of stuttering have become more(More)
Positron emission tomography (PET) can be used to map brain regions that are active when a visual object (for example, a hand) is discriminated from its mirror form. Chronometric studies suggest that viewers 'solve' this visual shape task by mentally modelling it as a reaching task, implicitly moving their left hand into the orientation of any left-hand(More)
Non-invasive imaging of human inter-regional neural connectivity by positron emission tomography (PET) during transcranial magnetic stimulation (TMS) was performed. The hand area of primary motor cortex (M1) in the left cerebral hemisphere was stimulated with TMS while local and remote effects were recorded with PET. At the stimulated site, TMS increased(More)
The relationship between pretreatment regional cerebral glucose metabolism and eventual antidepressant drug response was measured using positron emission tomography (PET) in hospitalized patients with unipolar depression. Rostral anterior cingulate metabolism uniquely differentiated eventual treatment responders from non-responders. Hypometabolism(More)
Deficits in the perception of facial emotion have been demonstrated in patients with right-sided brain damage (RBD) and schizophrenia (SZ). Furthermore, recent speculations have implicated right-hemisphere dysfunction in Type II schizophrenics, especially those with a preponderance of "negative symptoms" and flat affect. The performance of SZ, RBD, and(More)
The primary neuropsychological theories of schizophrenia have emphasized disturbed dominant hemisphere functioning, although schizophrenics (SZs), particularly those with flat affect, may have deficits resembling those of patients with damage to their right hemisphere. SZs, right-brain-damaged patients (RBDs), and normal controls (NCs) were videotaped while(More)
Components of emotional processing were examined in psychiatric and neurological populations: communication channel (face/voice), processing mode (expression/perception), and emotional valence (positive/negative). These were assessed with an experimental affect battery which was administered to schizophrenic, unipolar depressive, right-brain-damaged,(More)
The purpose of this report was to examine facial asymmetry during the expression of positive and negative emotions. In addition, methodological factors in the study of facial asymmetry were considered. Subjects were 16 neurologically-healthy right-handed adult males, videotaped while posing eight facial expressions (positive and negative) under two(More)
This study examined the relationship between facial expression and social functioning in schizophrenic, depressed, right-brain-damaged, Parkinson's disease, and normal adult participants. Raters evaluated general intensity and amount of positive and negative facial emotion while participants were producing monologues regarding pleasant and unpleasant(More)
Flat affect is a major component of schizophrenia and is often also seen in neurological disorders. A preliminary set of comparisons were conducted to delineate neuropsychological mechanisms underlying flat affect in schizophrenia, and new measures are described for the assessment of affective deficits in clinical populations. Subjects were schizophrenic(More)