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Biomedical subjects

E Rodin

Publications and source records attributed to E Rodin.

At least 19 recordsLinked to original sources
PubMed1991

P3 latency determination by global field power in normal subjects.

The usefulness for assessing the peak latency of the P3 component of the cognitive event-related potential by means of global field power (GFP) measurements was investigated in 25 normal individuals. An initial test of the program utilizing the visual evoked potential elicited by checkerboard pattern reversals reproduced the findings originally reported by Lehmann and Skrandies demonstrating that the method is technically sound. Grand averages of the cognitive event-related potential showed on GFP determinations two peaks representing the N1 and P3 components, respectively. Correlation of P3 GFP latency with conventional peak determination showed that it was somewhat more closely related to the peak as seen on average reference recordings than when the linked ears were used as reference. Filtering the data to eliminate the intrusion of frequencies above 7 Hz shifted the curves somewhat to the right and correlation coefficients between GFP and conventional peak determinations decreased. GFP can aid in establishing the P3 peak latency, especially when two peaks are present in conventional recordings, e.g., at PZ and CZ with somewhat different latencies, but they cannot be substituted for conventional peak determinations, since the P3 may either show up only as a notch or not at all on the GFP curve, and the major GFP peak may not be related to the P3 component. The large standard deviation for the P3 component on conventional tracings is not reduced by GFP determinations.

Adult↗
PubMed1990

Comparison of conventional P3 determination with global field power in epilepsy patients.

The usefulness of global field power (GFP) determinations in assessing the cognitive event-related potential latency to an auditory "odd-ball" discrimination paradigm was explored in thirty epileptic patients. Relationships to measurements of intellectual and neuropsychologic test parameters were compared between conventional peak determinations and those obtained by GFP. Latencies as determined by GFP showed a greater number and more consistent relationships with neuropsychologic test measures than those obtained by conventional peak determinations. In some instances, GFP gave however also ambiguous results and the method cannot be substituted for conventional peak determinations, but must be used in conjunction in order to avoid spurious results.

Acoustic Stimulation↗
PubMed1989

Source derivation recordings of generalized spike-wave complexes.

The effects of the reference electrode on field changes during generalized spike-wave complexes were studied. Linked ears reference, common average reference and source derivation were compared. Source derivation proved superior to the common average reference because it was not influenced by the 'dipole' effect when large transients are distributed over all the electrodes. Source derivation retained the midfrontal field maximum as previously reported but also showed more frequent bilateral onset. Furthermore, it revealed the marked participation of temporal structure and enhanced biparietal or Pz components. The typical appearances of the maps are demonstrated and the implications discussed.

Action Potentials↗
PubMed1989

The cognitive evoked potential in epilepsy patients.

The P3 component to an auditory "oddball" stimulus was compared between 30 epilepsy patients and 27 age-matched normal controls. The P3 latency was significantly increased in the patients, but an increase beyond 3 standard deviations on two trials occurred in only 10 percent of the total sample and 13 percent when the age was restricted to less than 50 years. There were no significant differences in latencies for different seizure type or anticonvulsant levels. The best relationship on neuropsychologic performance was with the Trails B test. Since the exact latency of the P3 peak is at times difficult to determine and may involve arbitrary choices, it is proposed that when the test is used for clinical diagnostic purposes of dementia, the interpretation be limited to those instances where the P300 peak is either clearly normal or clearly present but prolonged beyond 3 standard deviations from age-matched normals. In the first instance, significant cognitive impairment is unlikely while it becomes very probable in the latter instance.

Adolescent↗
PubMed1988

An eigenfunction approach to the inverse problem of EEG.

A mathematical method of extracting salient features from electroencephalographic data called eigenfunction analysis is presented. It allows the reduction of 21 channels of EEG data to a few components which can be separated into those which are likely to originate relatively close to the surface and others of deeper origin. It was demonstrated that the original tracings can be reconstituted from these few components. The eigenvectors given an indication of the location of sources and the degree to which the eigenfunction appears on source derivation and average reference recordings allows an estimation of relative depth. The method has been successfully applied to EEG tracings from 10 patients and is illustrated in the case of a young woman suffering from complex partial seizures associated with a deep left temporal lesion. The implications for marked data reduction and the development of objective assessment of clinical neurophysiologic data are discussed.

Electroencephalography↗
PubMed1988

Extraction of "deep" components from scalp EEG.

In an attempt to delineate the relative contribution of surface versus deep components in the EEG of patients with 3 per second generalized spike-wave discharges and clinical petit mal seizures, a mathematical method was devised which allows the splitting of the EEG into two major subsystems. It is based on the observation that broad electrical fields tend to represent activity at deeper structures while discrete narrow fields centered at one electrode position tend to be of more superficial origin. Since source derivation intentionally suppresses broad potential fields, a differentiation between superficial and deep activity can be achieved by subtracting the source density values from the corresponding electrode potential values. This will provide those aspects of the EEG which are contributed mainly by deep generators. The resultant data can then be subjected to eigenfunction analysis which yields few uncorrelated components. The percentage of contribution of each electrode to the total component thus derived can then be displayed as a topographic map. When this methodology was applied to ictal EEGs of three patients consistent results were obtained. The "deep" data yielded mainly two components with mutually perpendicular directions.

Cerebral Cortex↗
PubMed1987

Cerebral electrical fields during petit mal absences.

The electrical fields of spike-wave complexes were plotted with the aid of a microcomputer in patients suffering from petit mal absences. The maximum positivity as well as negativity of the individual complexes was mainly in the frontal areas. While this observation was quite constant among different patients and different seizures within the same patient, the way in which these maxima were reached varied markedly. Even in the most regular patterns, successive spike-wave complexes within one seizure could show different origins and different spread of the field. Positive and negative components of the wave and occasionally of the spike could show different areas of onset. The earliest positive change was frequently in one occipital area or at Pz while negativity could be initiated in frontal or posterior head regions. The variability of onset and spread tended to be somewhat more marked for the positive rather than negative component. The spread of the field over the scalp was at times somewhat discontinuous and one or more preliminary peaks could occur which either disappeared or coalesced before the maximum was reached. The findings suggest that several intracortical generators contribute to the formation of the spike-wave complex but the frontal areas play the most crucial role and medial as well as lateral portions appear to be involved.

Adolescent↗
PubMed1987

Testosterone levels in adult male epileptic patients.

Total and free testosterone levels were assayed in 80 epileptic outpatients. The levels were in the low-normal range, and there was no dissociation between free and total levels observable in this sample. No relationships to clinical epilepsy parameters or anticonvulsant levels were found, but significant inverse relationships existed with age and the number of different anticonvulsant medications a patient was taking. The age effect was independent of the medication contribution and raises the question of premature aging of the sexual system in patients with epilepsy. Whether or not this is part of a more general premature decrease in the functions of the pituitary hypothalamic axis needs to be investigated.

Adult↗
PubMed1987

The cerebral electrical fields in cerebellar syndrome.

Cerebral electrical field mapping in a patient with a clinically pure cerebellar syndrome showed the field maximum at the Pz electrode position. Flash visual evoked potentials also showed, in addition to the occipital response, a late positive peak at 344 ms at Pz. The findings suggest that the Pz electrode may at times record far field activity from the cerebellum.

Cerebellar Ataxia↗
PubMed1985

Brainstem death.

A patient with the clinical picture of brain death resulting from brainstem hemorrhage and subsequent infarction is presented. The EEG showed activity similar to what has been described in the cerveau isolé animal preparations. Cortical evoked potentials were unobtainable from auditory or somatosensory stimulation, but of unusually high amplitude to flash stimuli. The point is made that a diagnosis of brain death cannot be made on clinical grounds alone when a patient is on life support systems, and the differences between cerebral death, brainstem death and brain death are discussed.

Aged↗
PubMed1984

Investigation of sex hormones in male epileptic patients.

Testosterone (T), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) levels were obtained in 33 male epileptic patients and 11 age-matched normal controls. The patients had significantly higher mean levels of FSH, LH, and PRL; T was decreased but not significantly so. Patients who had reported difficulties with sexual arousal on the Bear-Fedio Inventory had significantly lower T levels than those who did not. Increased LH levels correlated with younger age at onset of epilepsy and longer history of tonic clonic seizures. Increased PRL levels were related to a positive family history of epilepsy and nonfocal tonic clonic seizures. Anticonvulsant levels were unrelated to hormonal changes except for carbamazepine which was positively correlated with PRL levels.

Epilepsy↗
PubMed1984

The Bear-Fedio personality inventory and temporal lobe epilepsy.

We administered the Bear-Fedio inventory to normal controls and to patients with epilepsy, chronic pain, and psychiatric disorders. The trait scores showed progressive increase with the severity of psychiatric symptoms. There were no statistically significant differences between epileptic patients with diffuse spike wave discharges and those with focal temporal EEG abnormalities. Also, there were no significant differences in patients with left versus right temporal foci. The inventory is markedly influenced by intellectual factors and, to some extent, by gender and anticonvulsant drug levels, especially those of carbamazepine. The test in its current form measures overall psychopathology rather than a specific syndrome.

Epilepsy, Temporal Lobe↗
PubMed1977

The results of penicillin G Administration of chronic unrestrained cats: electrographic and behavioral observations.

Intramuscular administration of penicillin G was carried out in a series of 27 chronic cat preparations. In addition to the EEG, the high frequency components of cerebral electrical activity were also recorded from cortical and deep structures. Videotape recordings using split-screen technique allowed correlations of the animal's clinical state with the EEG. The results showed that 'spike-wave' type activity occurred earliest in the cortex. The discharges were also best formed in cortical and thalamic structures. The other deep structures showed characteristic bursting, but not of the 'spikewave' type variety. The cerebellum showed also early participation. Clinical expressivity of the bursts depended upon the state of alertness of the animal, the height of the spike components and the extent of depth participation. The high frequency recordings revealed characteristic alternation of decrease and increase in activity mostly in cortical structures and to a lesser extent in thalamus. Pontine and medullary reticular formation areas showed usually no changes in the high frequency records during the bursts. When major seizures were induced, they were always of focal onset rather than of the primary generalized type as one sees with pentylenetetrazol. Different cortical or deep structures served as the initiating site in different animals. It was concluded that systemic penicillin adminstration does not lead to a truly primary generalized form of epilepsy, but produces its effects by multifocal activation of various cerebral structures, with cortex and cerebullum usually showing earliest involvement.

Animals↗