Somatosensory evoked potential changes with a selective attention task.
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Adolescent↗
Biomedical subjects
J J Straumanis
Publications and source records attributed to J J Straumanis.
Influence of antipsychotic and antidepressant drugs on evoked potential correlates of psychosis.
This study aimed to (i) determine the changes in evoked potentials (EPs) associated with hospital treatment involving either antipsychotic (AP) drugs, tricyclic (TTR) drugs, or no medication (NM); (ii) determine which EP changes may be direct drug effects; (iii) evaluate effects of testing patients receiving AP and TR drugs on psychiatric correlates of EPs. Somatosensory (SEP) to left and right median nerve stimuli, visual (VEP), and auditory (AEP) EPs were recorded from one eye and 14 scalp leads. Patients were tested before and during AP (N = 28), TR (N = 10), or NM (N = 15) treatments; results of 35 age- and sex-matched nonpatients were compared with predrug and drug test results of 35 patients. Main findings included (i) with AP and TR drugs, SEP peak P30 amplitude tended to decrease and SEP N130 to increase; (ii) with AP drugs and NM, VEP amplitudes decreased; (iii) AEP amplitudes increased with AP drugs; (iv) changes in amplitude measures did not differ significantly between AP, TR, and NM treatments; (v) marked later SEP amplitude differences between patients and nonpatients were about the same for pretreatment and drug tests; (vi) patient-control differences were greater with drugs for VEPs and less with drugs for AEPs. It was concluded that later SEP amplitude correlates of psychopathology are little influenced by AP and TR drugs, but that VEP and AEP results are modified.
Adolescent↗
Psychotropic drugs and evoked potentials.
Effects of antipsychotic and antidepressant drugs and lithium carbonate (Li) on somatosensory, visual and auditory EPs were studied in psychiatric patients under treatment with those agents. A comparison group of patients treated without medication was also examined. The no medication group showed fewer EP changes on retest than the drug-treated groups. The effects of Li were greater than, and differed from, those of antipsychotics and antidepressants. EP changes with antipsychotics and antidepressants were relatively small and in the direction of normalization; these findings indicate that the pre-treatment EP differences from normal found in psychotic patients are probably not secondary to previous treatment with these drugs.
Antipsychotic Agents↗
The attention-related somatosensory evoked potential late positive wave in psychiatric patients.
Somatosensory evoked potential (SEP) late waves (P400) associated with selective attention were elicited by having subjects count electrical stimuli to one of four randomly stimulated fingers. P400 amplitude was lower in a diagnostically heterogeneous group of 20 psychiatric patients than in 16 nonpatients. Among patients, a general psychopathology factor derived from the Millon Clinical Multiaxial Inventory was significantly correlated with a factor accounting for most of the P400 amplitude variance. In psychiatric patients, attention-related late activity amplitude is apparently reduced from normal in evoked potentials of all modalities; degree of reduction appears quantitatively related to level of psychopathology.
Adolescent↗
Cerebral evoked potential changes produced by treatment with lithium carbonate.
To confirm and extend previous findings concerning evoked potential (EP) changes produced by lithium carbonate (Li), 12 depressive patients were studied while on placebo and on therapeutic doses of Li. Four kinds of EPs were recorded from 14 leads: somatosensory (SEP) to left (LSEP) and right (RSEP) median nerve stimuli; visual (VEP) to a checkerboard flash; auditory (AEP) to binaural click. Plasma and erythrocyte (RBC) Li levels and Hamilton Depression ratings were obtained. Li produced a number of amplitude changes in EPs of all sensory modalities, while there were few latency changes; in general, amplitudes of positive components were increased, while negative component amplitudes were reduced. The spatial distributions of EP peaks were mainly unaltered by Li. The amount of EP amplitude change with Li tended to be correlated with plasma and RBC Li levels. No convincing correlations were found between alterations in EPs and depression ratings. The nature of the EP changes with Li was generally not concordant with normalization of the deviant EP characteristics found in depressives. The findings indicate that Li produces more widespread CNS changes than suggested by previous reports; it appears that these tend to be related to Li levels, but not to the therapeutic effects of Li.
Adult↗
Intelligence as a factor in evoked potential studies of psychopathology. I. Comparison of low and high IQ subjects.
To evaluate possible influences of differences in intelligence on evoked potential (EP) relations to psychopathology, EPs of subjects with high and low scores on Raven's Progressive Matrices were compared. EPs to left median nerve (LSEP), right median nerve (RSEP), visual (VEP), and auditory (AEP) stimul were recorded from 15 leads. EPs of age- and sex-matched high and low IQ nonpatients (7 of each) and psychiatric patients (40 of each) were compared with respect to group mean EPs, amplitude, latency, and wave-shape stability measures; high and low IQ patients were also matched for diagnosis. Certain differences between high and low IQ subjects were common to both patients and nonpatients; lower IQ was associated with (i) higher early (before 100 msec) LSEP and RSEP amplitudes; (ii) lower later LSEP amplitudes; (iii) less late epoch LSEP wave-shape stability; (iv) less VEP wave-shape stability. Since these EP characteristics resemble deviations from normal reported for psychotics, intelligence differences could account for part, but by no means all, of the psychopathology-related EP differences. The relationship to IQ of the EP contour length ("string") measure, reported by Hendrickson and Hendrickson to be highly correlated with IQ, was also assessed; results were negative.
Adolescent↗
Intelligence as a factor in evoked potential studies of psychopathology. II. Correlations between treatment-associated changes in IQ and evoked potentials.
The first report of this series indicated that evoked potential (EP) characteristics previously shown to correlate with psychopathology differed between subjects with high and low intelligence test scores (IQ). This paper reports the results of an attempt to determine if these IQ-EP relationships could result from variations in clinical state, rather than from differences between groups in trait IQ. Two patient groups were selected on the basis of the shifts in their Raven Progressive Matrices scores from first test to retest: (i) increase of 17-46 percentile points; (ii) decrease of 5 to 30 points. Their somatosensory, visual, and auditory EPs were compared in several ways to determine if the EP changes on retest were correlated with the IQ changes, as predicted from the state hypothesis. The results did not confirm the predictions, suggesting that the previous findings reflected differences in trait IQ.
Adolescent↗
Confirmation of deviant EEG-evoked potential relationships in the neuroses.
A previous study of relationships between EEG and somatosensory evoked potential (SEP) measurements in psychiatric patients showed correlations between EEG and SEP amplitudes to be negative in nine neurotic patients and positive in nine age- and sex-matched nonpatients. The present study attempted to replicate this finding in 35 neurotics and 35 age- and sex-matched nonpatients. Data involved amplitudes of SEPs to right median nerve stimuli from frontal, central, and parietal leads and central and parietal EEG amplitudes (eyes open and closed), both obtained in the context of our comprehensive EP recording procedure. Correlations between SEP and EEG amplitudes in controls were generally positive, while those in patients tended to be negative or close to zero. No specific neurosis group differed from the others. The results confirm the previous finding in showing absence of normal EEG-SEP amplitude relationships in neurotic disorders.
Adult↗
Topography of sensory evoked potentials in depressive disorders.
This study investigated differences in evoked potential (EP) topography between psychotic depressives, nonpatient controls, chronic schizophrenics, and neurotic depressives. Somatosensory (SEP), visual, and auditory EPs were recorded from 14 scalp leads. Locations (latencies) of consecutive EP peaks in a given subject were identified visually in key leads; these latencies were used for computer measurements of amplitude in all leads. Four sets of age- and sex-matched groups were compared by multivariate profile analysis. Amplitude differences between groups agreed well with findings obtained by comparing group sum EPs, indicating convergence between the two measurement methods. Topographic differences involved mainly SEP peaks. Distributions of SEP peaks P90 (positivity at 90 msec), N130, and P290 showed more posterior maxima in psychotic depressives than controls, while P185 was maximal more anteriorly in depressives. Distribution of SEP peaks N20, N60, N130, and P185 differed between psychotic depressives and chronic schizophrenics. The topographic approach appears to provide new EP information of pyschiatric relevance.
Adolescent↗
Temporal variability of somatosensory, visual, and auditory evoked potentials in schizophrenia.
Previous findings in chronic schizophrenics showed greater than normal somatosensory evoked potential (SEP) waveshape stability before 100-ms after stimulus and reduced stability after 100 ms. To confirm and extend these findings, EPs to left and right median nerve stimuli, visual pattern flashes (VEPs), and auditory clicks (AEPs) were recorded from 14 locations in 86 patients and 33 controls. Three sets of analyses compared different patient groups with age- and sex-matched controls. The results confirmed previous SEP findings in chronic schizophrenics; no other subject group displayed the combination of high early and low late SEP stability. The SEP results did not generalize to VEPs and AEPs. Lead location was important for group differences. In overt schizophrenics, late epoch stability was low in all EPs. The results suggest certain limitations to the hypothesis of an impaired subcortical filtering mechanism in chronic schizophrenics.
Adolescent↗
Correlations between psychiatric diagnosis and some quantitative EEG variables.
Several methods of quantitative analysis were applied to the left parietal 'resting' EEGs of 48 nonpatient controls and 90 undrugged psychiatric inpatients. Patient and control groups, matched for age and sex, differed as follows: (a) Mean frequency was lower and frequency variability was greater in the total patient group than in controls. (b) Mean amplitude was higher and mean frequency lower in chronic schizophrenics than in controls; the amplitude differences were contributed mainly by female patients. (c) Amplitude and frequency means of nonpsychotic patients were intermediate between those of chronic schizophrenics and controls. (d) Mean amplitudes were greater and frequency variability was less in neurotics than in controls.
Adult↗
Somatosensory and auditory evoked potential studies of functional differences between the cerebral hemispheres in psychosis.
Evidence of lateralized hemispheric dysfunction in schizophrenia was previously found with a measure of visual evoked potential (VEP) wave-shape stability. The purpose of this study was to determine whether the VEP findings would extend to the auditory and somatosensory modalities. Measures of wave-shape stability were computed for auditory (AEP) and somatosensory (SEP) evoked potentials, recorded from one EOG and 14 scalp leads. Subjects were 74 unmedicated patients (49 schizophrenics, 25 nonpsychotics) and 27 nonpatients; two sets of age- and sex-matched comparison groups were formed. Main findings were: (i) Overtly psychotic schizophrenics exhibited lower than normal stability in left hemisphere AEPs (15-100 msec poststimulus). (ii) Both overtly psychotic and latent schizophrenics showed lower than normal wave-form stability, bilaterally, in the later epoch of AEPs (101-450 msec poststimulus). (iii) A subgroup of overt schizophrenics (other than chronic paranoid or chronic undifferentiated) had lower than normal stability in SEPs (15-100 msec) evoked by right median nerve stimuli and recorded from the right (ipsilateral) hemisphere. It was concluded that only the AEP results augment the previous VEP evidence indicating left hemisphere involvement in schizophrenic dysfunction.
Acoustic Stimulation↗
Evoked potential correlates of psychosis.
Evoked potential (EP) correlates of several psychiatric disorders were investigated by applying a comprehensive EP procedure to 102 psychiatric patients and 28 nonpatients. EPs to left and right median nerve shocks, visual pattern flashes, and auditory clicks were recorded from one EOG and 14 monopolar scalp derivations. Nine age- and sex-matched groups were compared to yield the following main results: (i) EPs of overtly psychotic patients (schizophrenics, depressives, manics) differed markedly from normal, while those of patients without overt psychosis (neurotics, personality disorders, latent schizophrenics) did not; in the overtly psychotic, later EP events (100 msec or more poststimulus) were attenuated. (ii) EPs of neurotic depressives differed greatly from those of psychotic depressives. (iii) A somatosensory negative peak occurring 60-msec poststimulus (N60) was more posteriorly distributed in chronic schizophrenics (paranoid, undifferentiated) than in any other subject group. The attenuated later EP activity associated with overt psychosis was interpreted as a concomitant of cognitive (attention?) impairment, rather than of emotional disturbance.
Acoustic Stimulation↗
Pattern evoked potential measurements suggesting lateralized hemispheric dysfunction in chronic schizophrenics.
Visual evoked potentials (VEP) were measured to obtain evidence concerning possible lateralized hemispheric dysfunction in schizophrenia. The main results are based on the spatial distribution (12 electrodes) of a measure of VEP wave form stability over time. Subjects were 86 psychiatric inpatients and 33 nonpatients; these were grouped in three ways to permit comparisons of various age- and sex-matched diagnostic classes. Main findings were: (i) VEP wave form stability was generally lower in all types of schizophrenia than in nonpatients, nonpsychotic patients and, probably, psychotic depressives. (ii) VEP stability differed more between the hemispheres in schizophrenics and psychotic depressives than in nonpsychotic subjects; in schizophrenics, left hemisphere stability was lower than normal, whereas it was normal in psychotic depressives. (iii) VEP stability differences between the hemispheres were also greater than normal in latent schizophrenics, with less stability on the left. The results provide a direct demonstration of a left hemisphere involvement in schizophrenic dysfunction.
Adolescent↗
Effects of lithium, triiodothyronine, and propranolol on human somatosensory-evoked potentials [proceedings].
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Evoked Potentials↗
Evoked potentials of schizophrenics in several sensory modalities.
This is the initial report of results obtained by a comprehensive approach to investigation of evoked potential (EP) characteristics of psychiatric patients. EP to left and right medion nerve, visual (checkerboard flash), and auditory (click) stimuli were obtained for 14 monopolar scalp and one EOG derivation in 32 schizophrenics and 16 nonpatients, matched for age and sex. Results showed amplitude attenuation of EP events 100 msec poststimulus or later in the patients' EPs of all modalities and in most lead locations. Attenuation of later EP events thus appears to be a general characteristic of schizophrenia. Comparisons of chronic paranoid and undifferentiated with other patient subtypes revealed a relatively specific correlate of the chronic subgroup, increased negativity of a negative somatosensory peak occurring 60 msec poststimulus (N60) at contralateral central leads.
Acoustic Stimulation↗
Electrophysiological effects of triiodothyronine and propranolol.
The effects of triiodothyronine (T3), T3 combined with propranolol, and propranolol alone on somatosensory evoked responses (SER) and EEG were studied in 2 groups each of 6 male volunteer subjects. The following results were obtained: (1) T3 increased SER amplitude during the first 100 ms after stimulus. (2) Addition of propranolol eliminated the SER amplitude increase resulting from T3 administration. (3) Neither T3 nor T3 plus propranolol significantly altered the mean level or the temporal variability of EEG amplitude and frequency. (4) There were no significant effects of propranolol alone on SER and EEG measures.
Adult↗
Application of factor analytic procedures to complex evoked potential measurements in psychiatric research.
Several factor analytic procedures were applied to data gathered with a modified somatosensory evoked potential (SEP) recovery function prodecure in 56 non-patients and 224 psychiatric inpatients. The data were analyzed for each option reflected in three main issues. (1) Which group should be used for calculating the basic factor structure--normals only or all subjects? (2) Should measurements be preadjusted for covariance with variables known to obscure events of interest? (3) Should varimax rotation be used, or are principal components sufficient? Using two criteria, interpretability of factors in relation to experimental design, and their ability to discriminate clinical groups, it appeared that: (1) choice of either population yielded similar results; (2) when measurements were pre-adjusted for covariance more interpretable factors, which also yielded clinical discriminations, were obtained by varimax rotations than by principal components, and (3) when data were not adjusted by covariance, principal component analysis produced a factor which, although less interpretable in relation to experimental design than the varimax factors, provided equivalent clinical discriminations.
Brain↗