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Poster #74 MISMATCH NEGATIVITY PEAK LATENCY AND NEGATIVE SYMPTOMS IN SCHIZOPHRENIA
Abstracts of the 3rd Biennial Schizophrenia International Research Conference / Schizophrenia Research 136, Supplement 1 (2012) S1–S375
nia are less accurate than healthy controls in their ability to perceive emotions. However, despite the important implications these deficits have for social functioning, the neural mechanisms that might underlie these deficits have not been elucidated. In the present study, we examined the spatial and temporal characteristics of affect perception in samples of schizophrenia patients and controls. Methods: To differentially activate M and P pathways, the spatial frequency of the original face stimuli was filtered. High frequency filtered stimuli bias the system toward M pathways, whereas low frequency filtered faces bias the system toward P pathways. The temporal characteristics of affect perception were examined by suppressing visual perception with a singlepulse transcranial magnetic stimulation (TMS). Intervals between target and TMS pulse were measured by stimulus onset asynchronies (SOAs), spaced in 50 ms increments from -150 to +150 ms (negative SOAs indicate forward masking, and positive SOAs indicate backward masking). To establish a baseline performance and allow subjects to get used to the stimuli, a block of 25 trials without a TMS pulse was administered at the beginning of the procedure. Results: A masking main effect of TMS was observed for both patients and healthy controls across the six SOAs. Repeated measures ANOVA was used to examine the effects of spatial frequency and SOA manipulations on the performance of patients and controls. Analyses revealed significant main effects for spatial frequency and group, as well as a significant spatial frequency by SOA interaction. No significant spatial frequency by group, SOA by group, or spatial frequency by SOA by group interactions were detected. Discussion: The present study was an effort to examine affect perception deficits in schizophrenia from the perspective of basic visual information processes. We developed and validated a methodology that would enable us to meaningfully probe the visual system using TMS. Findings revealed group differences in affect perception, such that individuals with schizophrenia performed consistently worse than controls across all conditions. We did not find an SOA by group interaction, which is typically detected with visual masking. This may be due to the fact that the visual mask has to activate visual channels in order to obtain a masking effect, whereas TMS, as it does not involve a visual stimulus, may be producing visual suppression in a way that does not involve activation of any specific visual channels. Thus, TMS masking may not necessarily detect any differential impairment in visual channels. Participants performed worse on filtered than non-filtered faces across all conditions. Interestingly, a significant spatial frequency by SOA interaction indicated that maximum visual suppression for unfiltered faces occurred at SOA of -50 ms, whereas maximum suppression for low and high frequency filtered faces occurred at SOA of +50. Based on basic research on vision and affect perception, this finding suggests that the critical time of affect perception occurs during the early V1 feedforward activity produced by the arrival of the bottom-up, afferent stimulus information from subcortical regions. On the other hand, perception of filtered faces, which are more difficult to process for affect, relies more heavily on feedback or reentrant processing from higher areas of the brain.
S307
Results: Patients showed attenuation of MMN amplitude to both deviants at all electrode sites and also impairment of cognitive function. Only MMN to duration deviant tones was significantly correlated with other measures. As reported before, decreased amplitude was related to impairment of psychosocial functioning and increased positive symptoms. There was no significant group difference with regard to peak latency. However a longer peak latency was significantly related to more pronounced negative symptoms in schizophrenia patients. Discussion: In healthy participants, MMN peak latency has previously been shown to be associated with the level of general (g) intellectual functioning. Impairment of the latter is likely to mediate the relationship betwenn the longer MMN duration peak latency with negative symptoms.
Poster #75 COGNITIVE AND ELECTROPHYSIOLOGICAL CORRELATES OF NOISE POWER IN SCHIZOPHRENIA Alvaro Diez 1 , Vanessa Suazo 2 , Pilar Casado 3 , Manuel Martin-Loeches 3 , Vicente Molina 4 1 Basic Psychology, Psychobiology and Methodology Department, School of Psychology, Salamanca, Spain; 2 Neuroscience Institute of Castilla and Leon, Salamanca, Spain; 3 UCM-ISCIII Center for Human Evolution and Behavior, Madrid, Spain; 4 Psychiatry Service, University Hospital of Salamanca‘, Salamanca, Spain Background: Brain activity is disorganized in the resting and task-activated states of schizophrenia.Most previous electroencephalographic power studies do not discriminate between these states. Noise power (scalp-recorded electroencephalographic activity unlocked to stimuli) may be of use for studying this disorganization. Methods: 54 schizophrenia patients (of which 26 were drug-free and 28 stable treated patients) and 27 healthy controls underwent clinical and cognitive assessments and an electroencephalographic recording during a P300 paradigm to calculate noise power magnitudes in the gamma and theta bands. A principal components analysis was used to determine the factor structure of noise power values across electrodes. Results: The principal components analysis revealed a theta noise factor and two gamma factors (roughly corresponding to the default mode network and a frontal topography). In comparison to controls, a significant increase of gamma noise values was common to drug-free and stable patients over Fz, P3 and, at trend level, over P4 electrodes (gamma default mode network factor). Both patients groups showed higher default mode network gamma noise factor loadings than healthy controls. In the patients, frontal gamma noise factor scores were significantly and inversely related to working memory and problem solving performance. Theta noise factor scores were also significantly and inversely related to problem solving in patients. There were no associations with symptoms. Discussion: There is a deficient regulation of functions subserving gamma activity that seems to be related to the default mode network and common to early, acute and stable stages of schizophrenia. Most likely some degree of inhibition is necessary for the functions underlying gamma oscillations.
Poster #74 MISMATCH NEGATIVITY PEAK LATENCY AND NEGATIVE SYMPTOMS IN SCHIZOPHRENIA Gudrun Sartory 1 , Christian Kärgel 2 , Daniela Kariofillis 1 , Bernhard Müller 2 1 University of Wuppertal, Wuppertal, Germany; 2 University of Duisburg-Essen, Essen, Germany Background: Mismatch Negativity (MMN) amplitude to deviant tones is reduced in schizophrenia indicating early auditory processing deficits. Attempts to relate the impairment to cognitive deficits and symptom domains have shown MMN amplitude reduction to be related to psychosocial functioning and, more recently, to positive symptoms. Rarely has the relationship between MMN latency and areas of dysfunction been investigated in schizophrenia Methods: In the present study, MMN latency and amplitude to frequency and shorter duration deviant tones were assessed in 31 patients with schizophrenia and 15 healthy control participants together with measures of cognitive function and clinical symptoms. Most patients (N=21) received atypical, six typical and four patients both types of antipsychotic medication. MMN was recorded at Fz, FCz and Cz electrode sites.
Poster #76 NOISE POWER AS A MEASURE OF EVENT RELATED AND SPONTANEOUS BRAIN ACTIVITY. A LONGITUDINAL STUDY Vanessa Suazo 1 , Alvaro Diez 2 , Pilar Casado 3 , Manuel Martin-Loeches 3 , Vicente Molina 1,4 1 Neuroscience Institute of Castilla and Leon, University of Salamanca Salamanca, Salamanca, Spain; 2 Basic Psychology, Psychobiology and Methodology Department, School of Psychology, University of Salamanca Salamanca, Salamanca, Spain; 3 UCM-ISCIII Center for Human Evolution and Behavior Madrid, Madrid, Spain; 4 Psychiatry Service, University Hospital of Salamanca Salamanca, Salamanca, Spain Background: Noise power was defined as the amount of EEG power unrelated to task performance (Winterer et al., 2004) and may be a useful approach to study cortical disorganization in schizophrenia. Event-related and spontaneous brain activity have been usually evaluated independently with EEG and fMRI. In this study we aim to assess the reliability and stability
nia are less accurate than healthy controls in their ability to perceive emotions. However, despite the important implications these deficits have for social functioning, the neural mechanisms that might underlie these deficits have not been elucidated. In the present study, we examined the spatial and temporal characteristics of affect perception in samples of schizophrenia patients and controls. Methods: To differentially activate M and P pathways, the spatial frequency of the original face stimuli was filtered. High frequency filtered stimuli bias the system toward M pathways, whereas low frequency filtered faces bias the system toward P pathways. The temporal characteristics of affect perception were examined by suppressing visual perception with a singlepulse transcranial magnetic stimulation (TMS). Intervals between target and TMS pulse were measured by stimulus onset asynchronies (SOAs), spaced in 50 ms increments from -150 to +150 ms (negative SOAs indicate forward masking, and positive SOAs indicate backward masking). To establish a baseline performance and allow subjects to get used to the stimuli, a block of 25 trials without a TMS pulse was administered at the beginning of the procedure. Results: A masking main effect of TMS was observed for both patients and healthy controls across the six SOAs. Repeated measures ANOVA was used to examine the effects of spatial frequency and SOA manipulations on the performance of patients and controls. Analyses revealed significant main effects for spatial frequency and group, as well as a significant spatial frequency by SOA interaction. No significant spatial frequency by group, SOA by group, or spatial frequency by SOA by group interactions were detected. Discussion: The present study was an effort to examine affect perception deficits in schizophrenia from the perspective of basic visual information processes. We developed and validated a methodology that would enable us to meaningfully probe the visual system using TMS. Findings revealed group differences in affect perception, such that individuals with schizophrenia performed consistently worse than controls across all conditions. We did not find an SOA by group interaction, which is typically detected with visual masking. This may be due to the fact that the visual mask has to activate visual channels in order to obtain a masking effect, whereas TMS, as it does not involve a visual stimulus, may be producing visual suppression in a way that does not involve activation of any specific visual channels. Thus, TMS masking may not necessarily detect any differential impairment in visual channels. Participants performed worse on filtered than non-filtered faces across all conditions. Interestingly, a significant spatial frequency by SOA interaction indicated that maximum visual suppression for unfiltered faces occurred at SOA of -50 ms, whereas maximum suppression for low and high frequency filtered faces occurred at SOA of +50. Based on basic research on vision and affect perception, this finding suggests that the critical time of affect perception occurs during the early V1 feedforward activity produced by the arrival of the bottom-up, afferent stimulus information from subcortical regions. On the other hand, perception of filtered faces, which are more difficult to process for affect, relies more heavily on feedback or reentrant processing from higher areas of the brain.
S307
Results: Patients showed attenuation of MMN amplitude to both deviants at all electrode sites and also impairment of cognitive function. Only MMN to duration deviant tones was significantly correlated with other measures. As reported before, decreased amplitude was related to impairment of psychosocial functioning and increased positive symptoms. There was no significant group difference with regard to peak latency. However a longer peak latency was significantly related to more pronounced negative symptoms in schizophrenia patients. Discussion: In healthy participants, MMN peak latency has previously been shown to be associated with the level of general (g) intellectual functioning. Impairment of the latter is likely to mediate the relationship betwenn the longer MMN duration peak latency with negative symptoms.
Poster #75 COGNITIVE AND ELECTROPHYSIOLOGICAL CORRELATES OF NOISE POWER IN SCHIZOPHRENIA Alvaro Diez 1 , Vanessa Suazo 2 , Pilar Casado 3 , Manuel Martin-Loeches 3 , Vicente Molina 4 1 Basic Psychology, Psychobiology and Methodology Department, School of Psychology, Salamanca, Spain; 2 Neuroscience Institute of Castilla and Leon, Salamanca, Spain; 3 UCM-ISCIII Center for Human Evolution and Behavior, Madrid, Spain; 4 Psychiatry Service, University Hospital of Salamanca‘, Salamanca, Spain Background: Brain activity is disorganized in the resting and task-activated states of schizophrenia.Most previous electroencephalographic power studies do not discriminate between these states. Noise power (scalp-recorded electroencephalographic activity unlocked to stimuli) may be of use for studying this disorganization. Methods: 54 schizophrenia patients (of which 26 were drug-free and 28 stable treated patients) and 27 healthy controls underwent clinical and cognitive assessments and an electroencephalographic recording during a P300 paradigm to calculate noise power magnitudes in the gamma and theta bands. A principal components analysis was used to determine the factor structure of noise power values across electrodes. Results: The principal components analysis revealed a theta noise factor and two gamma factors (roughly corresponding to the default mode network and a frontal topography). In comparison to controls, a significant increase of gamma noise values was common to drug-free and stable patients over Fz, P3 and, at trend level, over P4 electrodes (gamma default mode network factor). Both patients groups showed higher default mode network gamma noise factor loadings than healthy controls. In the patients, frontal gamma noise factor scores were significantly and inversely related to working memory and problem solving performance. Theta noise factor scores were also significantly and inversely related to problem solving in patients. There were no associations with symptoms. Discussion: There is a deficient regulation of functions subserving gamma activity that seems to be related to the default mode network and common to early, acute and stable stages of schizophrenia. Most likely some degree of inhibition is necessary for the functions underlying gamma oscillations.
Poster #74 MISMATCH NEGATIVITY PEAK LATENCY AND NEGATIVE SYMPTOMS IN SCHIZOPHRENIA Gudrun Sartory 1 , Christian Kärgel 2 , Daniela Kariofillis 1 , Bernhard Müller 2 1 University of Wuppertal, Wuppertal, Germany; 2 University of Duisburg-Essen, Essen, Germany Background: Mismatch Negativity (MMN) amplitude to deviant tones is reduced in schizophrenia indicating early auditory processing deficits. Attempts to relate the impairment to cognitive deficits and symptom domains have shown MMN amplitude reduction to be related to psychosocial functioning and, more recently, to positive symptoms. Rarely has the relationship between MMN latency and areas of dysfunction been investigated in schizophrenia Methods: In the present study, MMN latency and amplitude to frequency and shorter duration deviant tones were assessed in 31 patients with schizophrenia and 15 healthy control participants together with measures of cognitive function and clinical symptoms. Most patients (N=21) received atypical, six typical and four patients both types of antipsychotic medication. MMN was recorded at Fz, FCz and Cz electrode sites.
Poster #76 NOISE POWER AS A MEASURE OF EVENT RELATED AND SPONTANEOUS BRAIN ACTIVITY. A LONGITUDINAL STUDY Vanessa Suazo 1 , Alvaro Diez 2 , Pilar Casado 3 , Manuel Martin-Loeches 3 , Vicente Molina 1,4 1 Neuroscience Institute of Castilla and Leon, University of Salamanca Salamanca, Salamanca, Spain; 2 Basic Psychology, Psychobiology and Methodology Department, School of Psychology, University of Salamanca Salamanca, Salamanca, Spain; 3 UCM-ISCIII Center for Human Evolution and Behavior Madrid, Madrid, Spain; 4 Psychiatry Service, University Hospital of Salamanca Salamanca, Salamanca, Spain Background: Noise power was defined as the amount of EEG power unrelated to task performance (Winterer et al., 2004) and may be a useful approach to study cortical disorganization in schizophrenia. Event-related and spontaneous brain activity have been usually evaluated independently with EEG and fMRI. In this study we aim to assess the reliability and stability