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Biomedical subjects

B E Swartz

Publications and source records attributed to B E Swartz.

48 records · Page 3Linked to original sources
PubMed1979

Correlated effects of acetylcholine and cyclic guanosine monophosphate on membrane properties of mammalian neocortical neurons.

The effects of successive extracellular iontophoresis of acetylcholine (ACh) and atropine, and intracellular hyperpolarizing iontophoresis of cyclic GMP (cGMP) were studied in single neurons of the coronal-pericruciate cortex of awake cats. (a) Fifty-seven percent of the neurons that were tested responded to ACh with an increase in neuronal input resistance (Rm) and 50% responded to ACh with an increase in firing rate; 65% responded to cGMP with an increase in Rm and 60% responded to cGMP with an increase in firing rate. (b) After application of atropine, increases in Rm and firing rate associated with iontophoresis of ACh failed to recur. (c) Persistent increases in Rm following application of ACh accompanied by current-induced neuronal discharge were not diminished by subsequent application of atropine. (d) Atropine did not prevent increases in Rm and firing rate associated with intracellular iontophoresis of cGMP. (e) All cells tested with both ACh and cGMP that were shown initially to respond to extracellular ACh with increases in Rm were later shown to have comparable responses to cGMP.

Acetylcholine↗
PubMed1978

Effects of acetylcholine and cyclic GMP on input resistance of cortical neurons in awake cats.

The effects on input resistance (Rm) of extracellular iontophoresis of acetylcholine (ACh) and of intracellular iontophoresis of cyclic GMP (cGMP) were studied in neurons of the coronal-pericruciate cortex of awake cats. Control studies were also conducted including iontophoresis of saline extracellularly and 5'-GMP intracellularly. (1) Substantial increases in Rm occurred in approximately half the neurons given ACh or cGMP. (2) In the absence of associated repetitive spike discharge induced by intracellular injection of depolarizing current pulses during iontophoretic applications, the increases in Rm were transient occurring in less than 30 sec and lasting 4--5 min. (3) With associated current-induced spike discharge, the increases in Rm persisted for as long as the neurons could be held -- up to 1.5 h maximally. (4) Rm was not increased if saline was substituted for ACh, if 5'-GMP was substituted for cGMP, or if the neuron was only discharged repeatedly. (5) The magnitude and time course of both transient and persistent increases in Rm were comparable between cells given ACh or cGMP and whether action potentials and resting potentials were greater than or equal to 40 mV (average 47 mV)* or were less.

Acetylcholine↗
PubMedDate not supplied

Multidisciplinary analysis of patients with extratemporal complex partial seizures. I. Intertest agreement.

In 15 patients we hypothesized the origin of epilepsies to be 'extratemporal' based on videotaped seizures and surface EEG. Neuropsychological tests and neuroimaging (CAT, MRI, and PET scans) were then compared to the hypothesized ictal sites. Neuropsychological tests were abnormal in 86.6% and FDG-PET scans were abnormal in 73%. The neuropsychological tests and PET localized or lateralized areas of dysfunction to the same sites as electroclinical characteristics did in 85% of patients (P less than 0.01, Fisher exact test). No statistically significant correlation between lesion sites on CT and MRI and the ictal origin was observed due to the high proportion of normal or non-specific scans. These observations should be verified in a larger series of extratemporal seizures.

Adolescent↗
PubMedDate not supplied

Cortical metabolic activation in humans during a visual memory task.

A delayed match-to-sample (DMS) task of abstract, visual memory was performed during the uptake period of 18F-fluorodeoxyglucose. The increase in glucose uptake of cortical and subcortical regions ("activation") during the DMS task was compared with that during a control, immediate match-to-sample task using positron emission tomography. Both discriminant analysis and paired t tests supported the observation that the dorsolateral prefrontal area underwent the greatest activation, while a factor analysis revealed the functional correlation matrices of the tasks. Activations in the ventral premotor cortex and supramarginal and angular gyri were highly correlated with the change in the dorsolateral prefrontal cortex. The basal forebrain/ventral pole region showed a smaller but independently significant change. The findings support the role of the dorsal prefrontal region in the nonspatial working memory of humans.

Adult↗
PubMedDate not supplied

Complex partial seizures of hippocampal and amygdalar origin.

We studied the first clinical manifestations of 72 complex partial seizures (CPS) in 17 drug-resistant patients. CPS were indicated to be of hippocampal-amygdalar origin by scalp and depth EEG. We asked: (a) Do all CPS of hippocampal-amygdalar origin start with an initial motionless stare and/or oroalimentary automatisms? (b) If not, what other clinical manifestations appear at onset of the CPS? Results showed that approximately 39% of CPS begin with motionless staring, 25% with nonfocal discrete movements, 21% with oroalimentary automatisms, 10% with perseverative stereotyped automatisms, and 6% with vocalizations. Nonfocal discrete movements and oroalimentary automatisms were identified as the most common second and third clinical sequential manifestations during a CPS. We conclude that although approximately 60% of CPS of hippocampal-amygdalar origin start with motionless staring or oroalimentary automatisms, 40% do not.

Amygdala↗
PubMedDate not supplied

Neuroimaging in patients with seizures of probable frontal lobe origin.

Twenty-two patients whose electroclinical ictal characteristics suggested frontal lobe seizure foci were studied. Computed tomography (CT) scans showed abnormalities in only 32% of patients whereas magnetic resonance imaging was informative in 45%. 18FDG-Positron emission tomography (PET) scanning revealed decreased metabolism in 64% of the group. The areas of hypometabolism were focal, regional, or hemispheric. Focal frontal hypometabolism was significantly correlated with the electroclinical (semiologic) ictal localization. Therefore, FDG-PET scanning is a sensitive and specific technique for investigating patients with seizures of probable frontal lobe origins.

Deoxyglucose↗
PubMedDate not supplied

Neuroimaging in temporal lobe epilepsy: test sensitivity and relationships to pathology and postoperative outcome.

We studied patients with documented temporal lobe seizures to evaluate the predictive value of computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for surgical therapy and the relationships between these tests and the pathologic diagnoses. CT detected abnormalities in 32.5%, with an accuracy of 19% when accuracy was defined as congruence with electrophysiologic studies. MRI detected abnormalities in 81%, with an accuracy of 67%. FDG-PET detected abnormalities in 85%, with an accuracy of 82%. Pathologic change was detected in 79% of the excised temporal neocortex, 65% of amygdalae, and 93% of hippocampi. After follow-up periods of 20-71 months (mean 41 months), 67% of patients were free of seizures and 94% had at least a 90% reduction in seizure frequency. There was no relationship between the type of abnormality on MRI or the type of pathology and postoperative outcome. Better outcomes were associated with focal or regional ictal onsets as recorded by surface EEG. Worse outcomes were associated with hypometabolism that extended outside the temporal lobe. Pathologic change in the temporal neocortex was associated with extension of hypometabolism outside the temporal lobe.

Adult↗
PubMedDate not supplied

Electrophysiology of bimanual-bipedal automatisms.

To determine the localizing value and electrophysiology of bimanual-bipedal automatisms (BBAs), we studied these behaviors in 54 seizures of 8 patients with temporal or frontal lobe seizure onset. BBAs occurred with a frequency of 27% in frontal lobe epilepsy (FLE) and of 7% in temporal lobe epilepsy (TLE). The distribution of electrode sites showing ictal activity during these automatisms was significantly different in the two patient groups (0.0001 Chi-square). Mesio- and/or laterotemporal plus orbital frontal areas were involved areas when the behaviors appeared in patients with TLE; dorsolateral and mesiofrontal regions were the most commonly involved when the behaviors occurred during the course of frontal lobe seizures. We concluded that BBAs represent activation of frontal lobe circuitry but are not unique to seizures of frontal lobe origin. Eyelid flutter and repetitive body movements in either the axial or sagittal plane were significantly associated with the frontal lobe group whereas oral-alimentary automatisms were associated with the temporal lobe group. Thus, these associated behaviors may help indicate whether a frontal or temporal lobe seizure onset has occurred when BBAs are observed. A new concept of ictal expression is proposed to conform with the results as well as with other apparently disparate ictal behaviors that may have localizing value.

Adult↗