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Biomedical subjects

B T Volpe

Publications and source records attributed to B T Volpe.

At least 91 records · Page 5Linked to original sources
PubMed1982

Temporal order judgments with amnesia.

The hypothesis that patients with anterograde amnesia fail to recognize the temporal relations among recognizable past events was evaluated. Experiment 1 showed that order recognition for words in a list was at chance levels even though event recognition was significantly above chance. The same pattern did not obtain for intact adults. Experiment 2 examined event and order recognition for news events. Amnesics' event recognition for news events was quite accurate and comparable to controls, yet their order recognition was significantly below that of controls, again at chance levels. It is argued that the failure to encode the temporal relations among events has broad consequences for memory performance in general.

Adult↗
PubMed1982

Evidence for paracallosal verbal transfer after callosal section. A possible consequence of bilateral language organization.

The covert interhemispheric transfer of linguistic information was demonstrated in a commissurotomy patient with bilateral language organization. It was found that under conditions of unilateral stimulation, a verbal association established in one hemisphere was available to the untrained hemisphere as well. Such interhemispheric transfer was observed only for phonetically codable information. Moreover, transfer was not observed under conditions of simultaneous bilateral stimulation. These results suggest that the point of convergence between the left and right hemisphere language systems allows for the paracallosal transfer of linguistic information.

Adult↗
PubMed1982

Cortical mechanisms involved in praxis: observations following partial and complete section of the corpus callosum in man.

In patients who have undergone complete section of the corpus callosum for intractable epilepsy, lateralized presentation of visual nonverbal stimulation showed that the coordination of motor acts by either hand is controlled exclusively by the contralateral hemisphere. When two patients had serial operations consisting of an initial division of the splenium and posterior 3 cm, followed by complete callosal division, an opportunity arose to test the explicit cortical pathways involved in ipsilateral control. Between operations, these patients could not coordinate movements of the hand ipsilateral to the hemisphere receiving the command. This suggested that for visual nonverbal stimulation, the posterior 3 cm of corpus callosum is necessary for control of the ipsilateral hand; the rostral callosum cannot transfer sensorimotor commands. Also, contrary to current views, each hemisphere can carry out sequentially dependent motor activity.

Corpus Callosum↗
PubMed1981

Cognitive interaction after staged callosal section: evidence for transfer of semantic activation.

Sensory and cognitive functions were assessed in a right-handed male before and after partial and complete callosal commissurotomy. After the initial posterior section was made, there was no evidence of interhemispheric sensory transfer, although the left hemisphere did have access to stimulus-related semantic and episodic information from the right hemisphere. After the callosum was completely sectioned, this exchange was no longer observed.

Adult↗
PubMed1981

Can left-handed writing posture predict cerebral language laterality?

In terms of cerebral lateralization of function, left-handed persons represent a more heterogeneous group than right-handed persons. Some evidence suggests that left-handed subgroups can be identified on the basis of the following two types of writing posture: (1) inverted posture that indicates ipsilateral hemisphere language capability and (2) straight writing posture that indicates contralateral hemisphere language capability. A direct test of this hypothesis with an intracarotid amobarbital sodium injection failed to support these predictions. For clinical decisions in which the hemisphere subserving language is necessary, one should rely on direct assessment with the use of the amobarbital injection technique.

Adult↗
PubMed1981

Environmental reduplication associated with right frontal and parietal lobe injury.

Four patients with environmental reduplication, a specific form of spatial disorientation and confabulation are described. The patients maintained that their hospital rooms were located in their homes. Each patients had evidence of right frontal or right parietal injury based upon computed tomography, neurosurgery, and neuropsychological testing. The factors associated with environmental reduplication were: impaired spatial perception and visual memory, inability of the patients to recognise the inconsistency between their believed location and their actual location, confusion soon after admission to hospital, and a strong desire to be at home.

Adult↗
PubMed1981

Variability in right hemisphere language function after callosal section: evidence for a continuum of generative capacity.

Two recent patients in our behavioral series investigating the psychological effects of callosal section exhibit right hemisphere language. Using lateralized visual and auditory stimulation, semantic, phonetic, and expressive linguistic functions were examined. While the right hemisphere language systems in both patients were shown to be capable of semantic information processing, they differed in their abilities to process phonetic information, follow verbal commands, and produce linguistic responses. It is argued that the differences between left and right hemisphere language systems are quantitative and are best characterized along a continuum of generative capacity. It is the variability in such capacity that appears to be responsible for the variability in right hemisphere language function within the split-brain population.

Adult↗
PubMed1979

Plasticity in speech organization following commissurotomy.

For three-and-a-half years we have been studying the cognitive and conscious mechanisms in a remarkable 18-year-old man: Case P.S. This unique individual had his corpus callosum divided in order to control intractable epilepsy. Although for some time after the operation he appeared like other split-brain patients, unable to describe verbally stimuli directed to his mute right hemisphere, he behaved as if he was capable of comprehending a wide range of language-related stimuli directed to that hemisphere. Spelling by choosing the appropriate letters with his left hand, he could process nouns, verbs, rhymes, antonyms, and superordinate concepts. When asked about tachistoscopic presentations delivered to his left visual field, he either said he had seen nothing, or only a flash of light. He was also unable to identify verbally tactile 'sterognostic' inputs to his left hand. In the last year P.S. has begun to speak about stimuli directed to his right hemisphere. This series of experiments suggests that this speech is not interhemispheric transfer within the visual modality. Further, plotting the relative increased proficiency of verbal description of inputs directed to the right hemisphere, this speech system seems to be in a process of continuing development.

Cerebral Cortex↗
PubMed1979

Spatially oriented movements in the absence of proprioception.

Four patients, each with a cerebrovascular accident in a different arterial supply, had unilaterally impaired somatosensory function that included eficits in the perception of touch and proprioception. In spite of central nervous system lesions and absent proprioception, all patients accurately performed spatially oriented movements with the deafferented hand. These observations suggest that execution of certain motor programs can proceed effectively without peripheral feedback.

Adult↗
PubMed1978

Normal CAT scans in craniopharyngioma.

Three patients with symptoms of headache and vision loss had normal routine CAT scans, with and without injection of contrast medium, as their initial diagnostic procedure. Subsequent pneumoencephalography revealed large suprasellar masses, which at operation were found to be partially cystic craniopharyngiomas. The findings emphasize the existence of craniopharyngiomas that are isodense with brain and may not be detected on routine CAT scan. When a patient's clinical presentation suggests chiasmal or sellar abnormalities, the pneumoencephalogram remains the most accurate diagnostic procedure.

Adult↗
PubMed1975

Bile salt alteration of ion transport across jejunal mucosa.

The effect of conjugated dihydroxy and trihydroxy bile salts on electrolyte transport across isolated rabbit jejunal mucosa was studied. Both taurochenodeoxycholic acid and taurocholic acid increased the short-circuit current (Isc) in bicarbonate-Ringer solution but not in a bicarbonate-free, chloride-free solution. Taurochenodeoxycholic acid was significantly more effective than taurocholic acid in increasing Isc. The presence of theophylline prevented the taurochenodeoxycholic acid- and taurocholic acid-induced increase in Isc. Transmural ion fluxes across jejunal mucosa demonstrated that 2 mM taurochenodeoxycholic acid decreased net Na+ absorption, increased net Cl- secretion and increased the residual flux (which probably represents HCO3- secretion). These studies support the hypothesis that cyclic AMP may be a mediator of intestinal electrolyte secretion.

Animals↗
PubMedDate not supplied

An animal model of human-type memory loss based on aging, lesion, forebrain ischemia, and drug studies with the rat.

The goals of this research were to develop a within-subject test of spatial working memory and performance for the rat in a T-maze, based on a delayed alternation, or "win-shift" foraging strategy. Using this model, specific aims were to compare the effects of: (1) age, (2) basal forebrain, medial septal, and amygdala lesions, (3) four vessel occlusion (4-VO), forebrain ischemia, and (4) physostigmine, scopolamine, arecoline, piracetam, and clonidine on memory and performance of young middle-aged, and old rats. Aging significantly impaired working memory and performance of Long-Evans rats. Memory of septal and basal forebrain, but not of amygdala lesioned rats was significantly impaired without effects on performance. Transient, 4-VO forebrain ischemia produced significant memory impairment, without effects on performance, and highly selective CA1 cell loss in the hippocampus. Physostigmine enhanced working memory in middle-aged and old rats. Scopolamine impaired memory in young, middle-aged, and old rats. Physostigmine reversed the scopolamine impairments of working memory. Arecoline enhanced memory in old rats without effects on performance. Piracetam and clonidine had no direct effects on memory, but piracetam increased and clonidine decreased speed of performance. From the aging, lesion, ischemia, and drug studies it was concluded that there was a convergence of evidence from 4 different approaches for a critical role for the hippocampus, particularly the CA1 fields, in spatial working memory.

Aging↗