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E L Merrin

Publications and source records attributed to E L Merrin.

16 recordsLinked to original sources
PubMed1992

31Phosphorus magnetic resonance spectroscopy of the temporal lobes in schizophrenia.

Eleven schizophrenic patients and nine normal controls were studied using in vivo 31Phosphorous magnetic resonance spectroscopy (31P MRS) to test the hypothesis of metabolic asymmetry in the temporal lobes in schizophrenia. The controls did not demonstrate any asymmetry of phosphorous metabolite ratios, percentage of phosphorous metabolites, or pH. In the schizophrenics, however, phosphocreatine/beta-adenosine triphosphate (PCr/beta-ATP) and phosphocreatine/inorganic phosphate (PCr/Pi) effects appeared to primarily reflect higher ratios on the right side, while the percentage of beta-ATP appeared to primarily reflect higher relative concentrations in the left temporal lobe. Moreover, significant negative correlations were noted between total Brief Psychiatric Rating Scale scores and PCr/beta-ATP in both the right and left temporal lobes. These results support the hypothesis of an asymmetric distribution of 31P metabolites in the temporal lobe of schizophrenic patients, and also show an association between temporal lobe phosphorous metabolism and the severity of psychiatric symptomatology.

Adenosine Triphosphate↗
PubMed1992

Negative symptoms and EEG alpha activity in schizophrenic patients.

Quantitative analyses of electroencephalographic (EEG) recordings in schizophrenic patients have often demonstrated reduced alpha band (8-13 Hz) activity. However, this finding is not universal and there is some evidence that subgroups of schizophrenics may differ in overall or lateralized levels of EEG alpha activity. To investigate this issue, the authors examined relationships between clinical ratings performed at the time of EEG recording and resting alpha power and coherence in 14 medication free schizophrenic patients. Nine channels of previously recorded resting (eyes open) EEG were transformed to average reference prior to spectral analysis and transformed to source derivation prior to calculation of inter-electrode coherences. Patients were rated with the Brief Psychiatric Rating Scale (BPRS), from which subscales corresponding to negative symptoms, positive symptoms, paranoia, and anxiety/depression were derived. Ratings and EEG measures were also obtained on 10 of the schizophrenic patients after neuroleptic treatment. Multiple regression with repeated measures was used to examine the influence of the subscale scores on bilateral log alpha power and both within- and between-hemisphere alpha coherence at selected locations. Prior to treatment, negative symptoms varied inversely with alpha power (p < 0.02), within-hemisphere alpha coherence (p < 0.03), and between-hemisphere coherence (p = 0.053). The effect of negative symptoms on alpha power was bilateral, but the effect on within-hemisphere coherence tended (p = 0.053) to be right-sided. After treatment these relationships were no longer present. The possible implications of and the effects of drug treatment on an association between negative symptoms and reduced alpha activity are discussed.

Adult↗
PubMed1991

Average reference EEG lateralization in schizophrenic patients.

The authors transformed 9 channels of electroencephalogram (EEG) to 10 channels of average reference data and compared EEG asymmetry between medication-free (for 2 weeks) schizophrenic male patients (n = 14), male patients with affective disorder (n = 9), and normal males (n = 13). Multivariate analyses failed to find lateralized differences between groups in resting and task EEG. Neuroleptic treatment (n = 11) was associated with asymmetrical changes in beta power rather than in alpha and theta, as previously reported. There were no relationships between clinical ratings (based on the Brief Psychiatric Rating Scale and subscales) and alpha asymmetry. The authors discuss conflicts with previous findings and the advantages of minimizing reference bias when studying EEG topography.

Adult↗
PubMed1990

Story recall under monaural and binaural conditions in psychiatric patients.

It has been reported that a large proportion of patients with major psychiatric disorders can recall a short story better if they listen with one ear rather than the other (monaural asymmetry), and that binaural performance is worse than with the better ear alone (binaural inferiority). Blocking the poorer ear with an earplug is said to significantly improve speech comprehension in daily life. Because of the theoretical and practical significance of these reports, we have attempted a replication. Forty-four psychotic patients, primarily schizophrenic, were studied. We found a lower incidence of abnormal monaural asymmetry and binaural inferiority than was previously reported. The incidence remained low whether we considered the entire sample or subgroups defined by diagnosis, chronicity, or age. Retest reliability was poor. We also found that binaural superiority was as common as binaural inferiority, and concluded that the instances of relative binaural inferiority in our sample were primarily due to chance. Differences in methods, subject selection, or medication were considered, but did not clearly account for the discrepancies between our results and previous studies. Future research must focus on establishing the conditions determining reliability.

Adolescent↗
PubMed1990

Topographic segmentation of waking EEG in medication-free schizophrenic patients.

Lehmann has demonstrated that EEG topography can be used to segment EEG map series into a sequence of spatially stationary segments characterized by location of potential maxima and minima. We employed topographic segmentation techniques to study 9 channel EEGs recorded from 11 medication-free schizophrenic patients and 10 normal controls during resting and active task conditions, retesting 8 patients after neuroleptic treatment. To define EEG segments, average reference potential maps corresponding to global field power peaks in theta, alpha, and low beta activity were classified according to locations of extreme minimum and maximum values. Normals and schizophrenics did not differ in the number or types of switches between segments, or the frequency of hemisphere crossing of potential extrema. However, EEGs of normal subjects were characterized by significantly more (P less than 0.003) unused theta segment types (of a theoretically possible 36). Moreover, medication significantly (P less than 0.02) increased the number of unused theta segment types in EEGs of schizophrenics. We interpret these findings as evidence of increased spatial variability of brain electrical activity in schizophrenics and discuss their functional implications.

Adult↗
PubMed1989

EEG coherence in unmedicated schizophrenic patients.

We have recently shown that electroencephalogram (EEG) coherence data recorded with common reference methods, including those obtained from schizophrenics, are confounded by power and phase effects. Three published reports using bipolar recordings found that EEG coherence was higher in schizophrenics; however, only medicated patients were studied. To extend these findings, we measured EEG coherence from bipolar EEG recordings in unmedicated schizophrenics (n = 10), affective disorder patients (n = 8), and normal controls (n = 13) during resting and task conditions. Seven schizophrenics were restudied after a period of neuroleptic treatment. Schizophrenics had higher across-task interhemispheric (p less than 0.05) and intrahemispheric (p less than 0.04) coherence in the theta band and tended to have higher intrahemispheric alpha coherence (p less than 0.08). Medication treatment was associated with clinical improvement and increases in spectral power, but not with changes in coherence values. These results confirm those obtained by earlier investigations and suggest that increased coherence reflects the presence of anomalous cortical organization in schizophrenics rather than medication effects or transient states related to acute clinical disturbance.

Adult↗
PubMed1989

The variety of relations between spatial frequency and reaction time.

While stimuli of lower spatial frequency often result in faster responses, this is not invariably the case. Some individuals respond faster to high frequency stimuli on tasks for which most others respond faster to low frequency stimuli. Past experience can also determine the degree to which a low frequency stimulus will mask a high frequency stimulus. These observations suggest that the effects of spatial frequency on visual information processing are under the control of higher level cognitive operations.

Adult↗
PubMed1988

Common reference coherence data are confounded by power and phase effects.

Coherence analysis of the EEG is used to study the coupling between cortical regions. High coherence between signals recorded at 2 electrodes is interpreted as evidence for neuroanatomic connections between the cortical areas underlying the electrodes. When common reference recordings are used, coherence measures the relationship between 2 time series, each of which is the difference between 2 signals measured at the scalp and is confounded by spectral power and phase at the recording and reference electrodes. Using multi-channel EEG data from 3 subjects, we illustrate the confounding of common reference data coherence computations and demonstrate the extreme effects of power and phase changes on coherence by simulating these changes in the EEG data. Common reference coherence data can be either inflated or deflated as a consequence of activity (i.e., spectral power) at the reference. Phase relationships among the reference and recording time series modulate the power effects on coherence. Both the power and phase effects can vary dramatically across frequencies, having profound and complicated effects on the shape of the coherence function. Based on these considerations, we conclude that common reference coherence data must be interpreted very cautiously and recommend that a new body of EEG coherence data must be gathered using reference-free recording methods before the utility of EEG coherence analysis for understanding brain function can be determined.

Cerebral Cortex↗
PubMed1987

The Neurobehavioral Cognitive Status Examination: comparison with the Cognitive Capacity Screening Examination and the Mini-Mental State Examination in a neurosurgical population.

Studies to determine the validity of the Mini-Mental State Examination (MMSE) and the Cognitive Capacity Screening Examination (CCSE) have indicated unacceptably high false-negative rates for these tests. To determine whether a new examination, the Neurobehavioral Cognitive Status Examination (NCSE), is more sensitive in the detection of cognitive dysfunction, we compared the three examinations in 30 patients with documented brain lesions. The CCSE had a false-negative rate of 53%; the MMSE, of 43%; and the NCSE, of 7%. The sensitivity of the NCSE is derived from two features of its design: the use of independent tests to assess skills within five major areas of cognitive functioning, and the use of graded tasks within each of these cognitive domains.

Adult↗
PubMed1986

EEG asymmetry in schizophrenic patients before and during neuroleptic treatment.

Lateral asymmetry of electroencephalographic (EEG) spectra was assessed in schizophrenic patients compared to normal controls. Ten predominantly unmedicated schizophrenic inpatients and nine normal controls performed monitored cognitive tasks during bilateral recording of EEG from parietal and temporal sites. Lateralization of EEG power in five frequency bands was compared between the groups; separate analyses were performed for linked ears and vertex references. A subsample of schizophrenic patients was restudied after a period of neuroleptic treatment. All significant group differences were obtained with the linked ears reference only. Pretreatment schizophrenics manifested relatively less alpha power over the right hemisphere during all conditions than controls, particularly in the parietal leads. After treatment, there was a significant shift in alpha lateralization toward the control values. These latter effects were also present in the theta frequency band to a lesser extent.

Adult↗
PubMed1986

Dual factitious disorder.

The DSM-III classification of factitious disorders encourages artificial separation into disorders with physical and those with psychologic symptoms. Despite documented examples of similar patients who present with psychiatric complaints, Munchausen's syndrome is usually considered a form of chronic factitious physical disorder. Three patients with both factitious physical and psychologic symptoms are presented. These patients illustrate the importance of focusing on the fundamental behavior of assuming the patient role, rather than on the specific category of symptoms. We recommend that the category of symptoms be used as a modifying statement, rather than defining separate disorders.

Adult↗
PubMed1985

Motor and sighting dominance in schizophrenia and affective disorder. Evidence for right-hand grip strength prominence in paranoid schizophrenia and bipolar illness.

Unusually frequent sinistral motor and sighting dominance have sometimes been reported in schizophrenics, although the majority of patients are still dextral. In this study, assessment of lateral dominance also included a measure of grip strength--a potentially more sensitive index of dominance or lateralised impairment; schizophrenics, non-schizophrenic patients (affective disorder), and normal controls were studied. There were no differences in handedness or sighting dominance. Affective patients, particularly bipolar psychotics, had greater right-handed grip superiority than normals or non-paranoid schizophrenics. Paranoid schizophrenics were similar, being significantly greater in right-sided dominance than non-paranoids, who tended toward a smaller value than normals. Hand grip asymmetry was highly correlated with handedness in normals, but not in patients. The possibility is discussed that these results may reflect asymmetrical patterns of cerebral impairment or attentional bias.

Adult↗
PubMed1976

The Capgras phenomenon.

The underlying diagnosis of Capgras delusion is not found to be exclusively paranoid schizophrenia, nor is the sex exclusively female, as once was believed. Organic factors play a predominant role in many patients, and 41% of the cases are males. The age at diagnosis in those considered to be schizophrenic is older than is usually expected.

Adolescent↗
PubMedDate not supplied

Task-related EEG alpha asymmetry in schizophrenic patients prior to and after neuroleptic treatment.

EEG was recorded from bilateral frontal, central, temporal, and parietal leads (referenced to or transformed to a vertex reference) during cognitive activity in 13 normal controls, ten schizophrenics, and eight patients with affective disorders. All subjects were male and right-handed, and patients had been free of psychotropic medications for at least 2 weeks. A verbal (copying text) and spatial (copying shapes) task were matched for stimulus presentation and motor output. The number and rate of correct responses were recorded for each normal subject and 11 of the patients. As reported by others, normal subjects manifested a significant difference in alpha asymmetry between the tasks, reflecting relatively greater alpha suppression over the left hemisphere during the verbal task compared to the spatial task (P less than 0.05). This effect was not significant in either patient group. However, analysis of seven schizophrenics after neuroleptic treatment revealed robust effects of task on alpha asymmetry similar to that present in the normal control group (P less than 0.02). The results suggest that abnormal task-related brain lateralization may be present in untreated schizophrenic patients, but it is state dependent and does not reflect permanent patterns of brain organization.

Adult↗