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Lateral cortical interactions in schizophrenia: A visual evoked potential study
252 Performance and an Overall score). Electrodermal activity (EDA) were monitored to a series of moderately intense tones (85dB). Nonresponding was defined as the absence of responses on any of the first two trials. Psychotic symptoms were rated with Positive and Negative Syndrome Scale (PANSS). We tested 14 persons with a DSM-IV diagnosis of schizophrenia and 23 nonpsychiatric controls. Compared to the controls, the patients bad marked problems in identifying (p<.0000) and describing problems (p<.0001) in social situations, in processing skills (p<.0000) as well as in sending skills (effectiveness in role-play) (p<.0000). Significant associations between AIPSS and EDA were observed for the cases but not for the controls. Low scores in Performance was associated with few skin conductance responses (r=.60, p<.02) and low skin conductance level (r=.57, p<.03). 9/14 patients (64,3 %) and 2/23 controls (8,7%) were electrodermal nonresponders. Nonresponding eases performed worse than responders concerning processing skills (t(12)=2.22, p<.05). A high level of negative symptoms was related to low scores in Performance (r=-.85, p<.0001). In conclusion, we found a relationship between electrodermal hypoactivity and interpersonal problem solving skills. These results accord with earlier findings relating low skin conductance activity to poor prognosis, poor premorbid adjustment, higher incidence of obstetric complications, birth during winter months and genetic vulnerability in schizophrenia. Donahoe, C.E, Carter, M.J., Bloem, W.D., Hirsch, G.L., Laasi, N. & Wallace, C.J. (1990). Assessment of interpersonal problem solving skills. Psychiatry, 53,329-339. Hultman, C. M. & Ohman, A. (1998). Perinatal characteristics and schizophrenia: electrodermal activity as a mediating link in a vulnerability-stress perspective. Int J Dev Neuroscience, 16, 307-316. Supported by the Swedish Medical Research Council and the Swedish Council for Working Life and Social Research
DO DISRUPTED SLEEP PROCESSES CAUSE SCHIZOPHRENIA SYMPTOMS ? A HYPOTHESIS M. S. K e s h a v a n
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA Schizophrenia is associated with alterations in slow wave sleep (SWS) and rapid eye movement (REM) sleep. The functional significance of these alterations is unclear. We hypothesize that abnormal sleep in schizophrenia can at least in part explain the cognitive and psychotic symptoms of this disorder. SWS may have a restorative effect on brain function, mediated by deactivation of the prefrontal cortex. Impaired prefrontal deactivation during SWS in schizophrenia, could lead to reduced prefrontal function. REM sleep is involved in a reverse learning process, mediated by the hippocampus, that can normally minimize spurious memories, while consolidating appropriate memories. Defective REM processes, resulting from an inadequate activation of limbic brain regions, might interfere with such reverse leanfing. This might in turn lead to the intrusion of redundant neural circuit activations (or parasitic states) into consciousness. In the context of the prefrontally mediated sensory gating deficits in schizophrenia, such redundant neural activations might be consciously experienced, and thus at least in part account for the psychotic symptoms Support for this hypothesis is derived from ongoing analyses of sleep data early course schizophrenia subjects. First, we have observed a relation between impaired working memory and SWS on one hand, and an association between memory consolidation and REM sleep on the other hand. Second, we have observed that decreased SWS is significantly correlated with the structural integrity of the prefrontal cortex. Finally, non-linear analyses of sleep data
16. Electrophysiology point to a reduced ability to deactivate the prefrontal cortex during non-REM sleep in schizophrenia relative to healthy controls. The proposed hypothesis raises testable predictions about whether reversing deficits can benefit at least some symptoms of schizophrenia.
LATERAL CORTICAL INTERACTIONS IN SCHIZOPHRENIA: A VISUAL EVOKED POTENTIAL STUDY D. Kim,* V. Zemon, A. Saperstein, E D. Butler, D. C. Javitt Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA Previous work has indicated that there may be altered excitatory as well as inhibitory neural function in schizophrenia. To ilwestigate nonlinear lateral inhibitory interactions in the visual system of patients with schizophrenia and age-matched controls, binocular and monocular stimulation were employed. The participants included 27 adults with schizophrenia and 20 age-matched healthy adults. Conventional steady-state VEPs to windmill-dartboard stimuli were obtained in 1-minute runs. The stimulus display subtended a visual angle of 7.5 degree at viewing distances of 114cm. The windmilldartboard (background ON) pattern consists of differentially modulating small neighboring spatial regions with temporal contrast reversal, a central disc (radius: visual angle of .9375) surrounded by three contiguous annuli (radii: 1st ring: 1.875; 2nd ring: 2.813 and 3rd ring: 3.75), all radially divided into light and dark segments. In the windmill-dartboard condition, the dynamic regions are sinusoidally contrast-reversed at ~4Hz while the surrounding static regions are fixed in contrast at the peak value (32%) of the dynamic region. As a consequence, the stimuli alternated between a windmill-like pattern and a dartboard-like pattern. In second condition, the partial-windmill pattern (background OFF), only a central disc and second annulus were contrast-reversed (sinusoidally at ~4Hz) and the rings (first and third) were kept at zero contrast (uniform fields of light set at the mean luminance level). Fourier analysis was used to extract the relevant frequency components in the response. One of two statistics, Tcirc2 or magnitude-squared coherence (MSC), was applied to each set of 10 epochs to estimate the noise level in the signal for each frequency component. A facilitation index (FI) and a suppression index (SI) were derived to quantify short- and long-range interactions, respectively. Short-range inhibition reflects function within a hypercolumn and long-range inhibition reflects between hypercolumns. The patients with schizophrenia show significantly greater shortrange lateral inhibition but not long-range lateral interactions compared to age-matched controls. Significantly greater short-range lateral inhibition in patients may reflect hyperactivation of intracortical, GABA-mediated inhibition within the width of a hypercolumn. Supported by Burrounghts Wellcome Fund (BWF1000618) and NIMH RO1 MH49334.
MISMATCH NEGATIVITY IN SCHIZOPHRENIA: COMBINING FMRI AND WHOLE-HEAD MEG T. T. Kircher,* A. Rapp, W. Grodd, K. M a t h i a k
Dept. of Psychiatry, University of Tuebingen, Tuebingen, Germany Background: Mismatch negativity (MMN) or field (MMNm) is an event-related brain potential that is sensitive to deviants within a sequence of repetitive auditory stimnli. It is thought to reflect short term sensory memory and is independent of higher level cognitive processes. The MMN is reduced in patients with schizophrenia. Little is known about the contribution of the different hemispheres and
International Congress on Schizophrenia Research 2003
DO DISRUPTED SLEEP PROCESSES CAUSE SCHIZOPHRENIA SYMPTOMS ? A HYPOTHESIS M. S. K e s h a v a n
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA Schizophrenia is associated with alterations in slow wave sleep (SWS) and rapid eye movement (REM) sleep. The functional significance of these alterations is unclear. We hypothesize that abnormal sleep in schizophrenia can at least in part explain the cognitive and psychotic symptoms of this disorder. SWS may have a restorative effect on brain function, mediated by deactivation of the prefrontal cortex. Impaired prefrontal deactivation during SWS in schizophrenia, could lead to reduced prefrontal function. REM sleep is involved in a reverse learning process, mediated by the hippocampus, that can normally minimize spurious memories, while consolidating appropriate memories. Defective REM processes, resulting from an inadequate activation of limbic brain regions, might interfere with such reverse leanfing. This might in turn lead to the intrusion of redundant neural circuit activations (or parasitic states) into consciousness. In the context of the prefrontally mediated sensory gating deficits in schizophrenia, such redundant neural activations might be consciously experienced, and thus at least in part account for the psychotic symptoms Support for this hypothesis is derived from ongoing analyses of sleep data early course schizophrenia subjects. First, we have observed a relation between impaired working memory and SWS on one hand, and an association between memory consolidation and REM sleep on the other hand. Second, we have observed that decreased SWS is significantly correlated with the structural integrity of the prefrontal cortex. Finally, non-linear analyses of sleep data
16. Electrophysiology point to a reduced ability to deactivate the prefrontal cortex during non-REM sleep in schizophrenia relative to healthy controls. The proposed hypothesis raises testable predictions about whether reversing deficits can benefit at least some symptoms of schizophrenia.
LATERAL CORTICAL INTERACTIONS IN SCHIZOPHRENIA: A VISUAL EVOKED POTENTIAL STUDY D. Kim,* V. Zemon, A. Saperstein, E D. Butler, D. C. Javitt Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA Previous work has indicated that there may be altered excitatory as well as inhibitory neural function in schizophrenia. To ilwestigate nonlinear lateral inhibitory interactions in the visual system of patients with schizophrenia and age-matched controls, binocular and monocular stimulation were employed. The participants included 27 adults with schizophrenia and 20 age-matched healthy adults. Conventional steady-state VEPs to windmill-dartboard stimuli were obtained in 1-minute runs. The stimulus display subtended a visual angle of 7.5 degree at viewing distances of 114cm. The windmilldartboard (background ON) pattern consists of differentially modulating small neighboring spatial regions with temporal contrast reversal, a central disc (radius: visual angle of .9375) surrounded by three contiguous annuli (radii: 1st ring: 1.875; 2nd ring: 2.813 and 3rd ring: 3.75), all radially divided into light and dark segments. In the windmill-dartboard condition, the dynamic regions are sinusoidally contrast-reversed at ~4Hz while the surrounding static regions are fixed in contrast at the peak value (32%) of the dynamic region. As a consequence, the stimuli alternated between a windmill-like pattern and a dartboard-like pattern. In second condition, the partial-windmill pattern (background OFF), only a central disc and second annulus were contrast-reversed (sinusoidally at ~4Hz) and the rings (first and third) were kept at zero contrast (uniform fields of light set at the mean luminance level). Fourier analysis was used to extract the relevant frequency components in the response. One of two statistics, Tcirc2 or magnitude-squared coherence (MSC), was applied to each set of 10 epochs to estimate the noise level in the signal for each frequency component. A facilitation index (FI) and a suppression index (SI) were derived to quantify short- and long-range interactions, respectively. Short-range inhibition reflects function within a hypercolumn and long-range inhibition reflects between hypercolumns. The patients with schizophrenia show significantly greater shortrange lateral inhibition but not long-range lateral interactions compared to age-matched controls. Significantly greater short-range lateral inhibition in patients may reflect hyperactivation of intracortical, GABA-mediated inhibition within the width of a hypercolumn. Supported by Burrounghts Wellcome Fund (BWF1000618) and NIMH RO1 MH49334.
MISMATCH NEGATIVITY IN SCHIZOPHRENIA: COMBINING FMRI AND WHOLE-HEAD MEG T. T. Kircher,* A. Rapp, W. Grodd, K. M a t h i a k
Dept. of Psychiatry, University of Tuebingen, Tuebingen, Germany Background: Mismatch negativity (MMN) or field (MMNm) is an event-related brain potential that is sensitive to deviants within a sequence of repetitive auditory stimnli. It is thought to reflect short term sensory memory and is independent of higher level cognitive processes. The MMN is reduced in patients with schizophrenia. Little is known about the contribution of the different hemispheres and
International Congress on Schizophrenia Research 2003