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Biomedical subjects

R G Heath

Publications and source records attributed to R G Heath.

At least 37 records · Page 2Linked to original sources
PubMed1980

Cannabis sativa: effects on brain function and ultrastructure in rhesus monkeys.

Two studies, designed to control for as many variables as possible, were conducted in 21 rhesus monkeys, some with brain electrodes and some unoperated, to determine the effects of marijuana on brain function and ultrastructure. Some monkeys were exposed to smoke of active marijuana (using different dose schedules), some were administered delta-9-THC (0.69 mg/kg iv), and others were exposed to smoke of inactive marijuana (from which all cannabinols had been removed). To deliver smoke to the monkeys, two different apparatuses were used. Dose schedules comparable to those of human marijuana smokers were established, as determined by plasma levels of delta-9-THC. After 2- to 3-months' exposure, the monkeys that were heavy- and moderate-smokers of active marijuana, and those administered delta-9-THC iv, developed chronic recording changes at deep brain sites, most marked in the septal region, hippocampus, and amygdala. These changes persisted throughout the exposure period (6 or 8 months) and during the postexposure observation period (1 to 8 months). Brains of these electrode-implanted monkeys, as well as those without electrodes that were exposed to delta-9-THC, showed ultrastructural alterations characterized by changes at the synapse, destruction of rough endoplasmic reticulum, and development of nuclear inclusion bodies. In contrast, brains of monkeys exposed to smoke of inactive marijuana and of unexposed controls showed no ultrastructural changes. The findings indicate that exposure to delta-9-THC, the psychoactive ingredient of marijuana, at doses commensurate with those used by human marijuana smokers can produce permanent alterations in brain function and structure of monkeys.

Animals↗
PubMed1980

Feedback loop between cerebellum and septal-hippocampal sites: its role in emotion and epilepsy.

Data collected in animal studies suggest the existence of a feedback loop between the cerebellum, septal region, and hippocampus, the same sites where anatomic connections were demonstrated in previous studies. In monkeys, stimulation through the vermis of the cerebellum inhibits epileptiform electroencephalographic activity at these supratentorial subcortical sites. In cats, macrostimulation of one of these sites consistently affects each of the other sites, either by facilitation or inhibition of unit activity. Further, in cats, there is a consistent relation between unit activity of the Purkinje cells and seizural activity in the septal region and hippocampus induced by hippocampal stimulation. Facilitation of Purkinje cell activity by the seizural activity appears to play a role in stopping the seizure. The possibility that the feedback relation is involved in epilepsy and emotional disorders and the mechanism by which cerebellar vermal stimulation has been useful in the treatment of these disorders are considered.

Amygdala↗
PubMed1980

Chronic cerebellar stimulation in the modulation of behavior.

From March 1976 until March 1979, 28 patients with disabling emotional symptoms were studied in the Psychiatry and Neurosurgery Departments at Tulane University, and pre-selected for cerebellar electrode implantation and subsequent cerebellar stimulation. This series include 12 patients with different types of schizophrenia; 7 epileptic patients with Grand Mal and/or psychomotor attacks, and concomitant psychiatric symptoms; 5 patients with intractable depression; and 4 patients with miscellaneous psychiatric symptoms. Follow-up results are graded as excellent, good, fair and poor. The authors conclude that significant improvement were observed in many patients, and the results, although preliminary and incomplete, are encouraging.

Cerebellum↗
PubMed1980

Phencyclidine abuse in New Orleans: medical, forensic, and laboratory aspects.

A one year study of phencyclidine abuse in New Orleans showed that 90% of the cases cannot be detected by routine laboratory methods. Fifty percent of all cases showed evidence of police intervention. Initial impressions covered a wide range of psychiatric and clinical diagnoses. Recurring psychiatric problems due to the presence of the drug would indicate observation for a period of at least 72 hours. Patterns of PCP abuse cross racial and ethnic boundaries and are found uniformly in all population groups.

Adolescent↗
PubMed1980

The cerebellar pacemaker for intractable behavioral disorders and epilepsy: follow-up report.

Thirty-eight patients who were intractably ill with a variety of behavioral disorders have been treated at Tulane with a chronically implanted cerebellar pacemaker. Included in the series ara schizophrenics, depressives, epileptics with behavioral pathology, and patients with severe organic brain pathology. The patients who have responded best to the treatment are those with depression, those with behavioral pathology consequent to epilepsy, and those with psychotic behavior consequent to structural brain damage. Results obtained in the chronic schizophrenic patients have been less favorable. The follow-up period ranges from a few months to 27 months. Overall, the results continue to be encouraging. Twenty-one percent of the patient group displayed structural evidence of cerebellar pathology that was not detected before operation, a finding which suggests that cerebellar damage may induce psychotic behavior.

Cerebellum↗
PubMed1979

Cannabis sativa: ultrastructural changes in organelles of neurons in brain septal region of monkeys.

Ultrastructural studies of layer V pyramidal neurons of the septal region of rhesus monkeys exposed to smoke of active marihuana and of those exposed to intravenous delta-9-THC revealed low volume density and various degrees of fragmentation and disorganization of rough endoplasmic reticulum. In contrast, no changes were observed in these neurons of the septal region of control monkeys (unexposed monkeys and one monkey exposed to smoke of inactive marihuana). There were no significant differences in volume density of mitochondria or golgi apparatus between exposed animals and controls.

Animals↗
PubMed1978

Cerebellar stimulation: effects on septal region, hippocampus, and amygdala of cats and rats.

The influence of the cerebellum on activity of the septal region, hippocampus, and amygdala of cats and rats was determined by obtaining unit recordings from those supratentorial sites with cerebellar stimulation. With stimulation of the postral vermis, fastigial nucleus, and intervening midline folia of the cerebellum, units in the septal region were facilitated, whereas those in the hippocampus were inhibited. Mixed results were obtained in the amygdala, some units being facilitated and others inhibited. Stimulation over the lateral cerebellar hemispheres and dentate nucleus, on the other hand, yielded no changes in activity, and stimulation of the posterior vermis produced inconsistent septal facilitation and no hippocampal response. With stimulation of the rostral cerebellar vermis and fastigial nucleus, evoked potentials at the supratentorial sites were of very short delay times, indicating direct pathways from the cerebellum to the septal region, hippocampus, and amygdala. When the dentate and fastigial nuclei were lesioned in cats, the firing rate of cells at supratentorial sites was not affected and cerebellar vermis stimulation did not significantly alter delay times of evoked responses, providing further evidence of a direct influence of the cerebellar vermis on the supratentorial sites. Relating these findings to previous patient and animal data provides a rationale for use of specific types of cerebellar simulation in the treatment of intractable behavioral disorders and epilepsy.

Amygdala↗
PubMed1977

Effects of Cannabis sativa on ultrastructure of the synapse in monkey brain.

Electron microscopic study of brain tissues of monkeys chronically exposed to psychoactive Cannabis showed widening of the synaptic cleft, electron opaque material in the cleft and in pre- and postsynaptic regions, and some "clumping" of synaptic vesicles. In contrast, tissues of control monkeys showed no ultrastructural changes.

Animals↗
PubMed1977

Modulation of emotion with a brain pacemamer. Treatment for intractable psychiatric illness.

A treatment involving chronic implantation of a receiver that can be activated by an external power source to stimulate specific brain sites has been used in 11 patients with intractable psychiatric illness. All of the patients, a heterogeneous group, had failed to respond to all indicated treatments. Length of illness varied from 6 to 23 years without significant remission. Of the 11 patients, four had uncontrollable violence-aggression (two with no demonstrable organic brain disease and two with brain pathology), five were chronic schizophrenics, and two had lifelong patterns of severe neurosis in addition to the disabling disorder for which the procedure was performed. Three of the 11 patients had seizures in addition to behavioral pathology. Ten of the 11 patients are out of the hospital and functioning without medications or other treatment. Some are symptom-free and others have shown significant improvement. The one patient who failed to respond had an organic lesion over the cerebellar site that was to be stimulated. The rationale for the procedure was based on data gathered during earlier therapeutic studies in patients with depth electrodes and extensive anatomical and physiological experiments in animals. The transistorized stimulator used in treating these patients is similar to stimulators being used for treatment of epileptic and spastic patients.

Adult↗
PubMed1976

Brain function in epilepsy: midbrain, medullary, and cerebellar interaction with the rostral forebrain.

Against the background previous findings in epileptic patients, in whom electroencephalographic recordings were obtained from numerous deep and surface brain sites during seizures, rhesus monkeys with electrodes implanted into specific brain sites were used to demonstrate anatomical connections by evoked potential techniques and to serve as models of experimental epilepsy. In the animals, many monosynaptic connections were revealed between forebrain sites consistently involved in seizures in patients and more caudal brain sites subserving functions of sensory perception, eye movement, synaptic chemical transmission, and motor coordination. Further, the participation of these interrelated sites during seizures was demonstrated. The findings provide an anatomical-physiological explanation for many of the clinical phenomena observed in epileptic patients and a rationale for the use of cerebellar stimulation as a treatment.

Animals↗
PubMed1976

Nationwide residues of organochlorines in wings of adult mallards and black ducks, 1972-73.

Organochlorine residues in wings of adult mallards and black ducks were monitored during the 1972-73 hunting season. DDE, DDT, DDD, dieldrin, and polychlorinated biphenyls (PCB's) were present in all samples. Mallard wings from Alabama contained the highest mean levels of DDE, DDT, DDD, dieldrin, and PCB's. Mallards and black ducks from the Atlantic Flyway and mallards from the Pacific Flyway contained significantly lower DDE residues than in 1969-70. Black ducks from the Atlantic Flyway contained significantly less dieldrin than in 1969-70, and mallards in the Central and Pacific Flyways contained significantly lower levels of PCB's. As in 1969-70, DDE residues were lowest in the Central Flyway and highest in the Atlantic Flyway. The average PCB level remained unchanged in the Atlantic Flyway but was higher in the Mississippi Flyway than in 1969-70, probably because of the unusually high levels in Alabama samples. All organochlorine residues in black ducks from the Atlantic Flyway significantly correlated. DDE concentrations in mallards from the Atlantic Flyway significantly correlated with those of DDT, DDD, and PCB's.

Animals↗
PubMed1976

Correlation of brain function with emotional behavior.

Identification of brain sites where physiologic activity was correlated with subjective emotional experiences in patients undergoing treatment was the starting point for our investigations of the neural basis for emotion and related clinically documented behavioral phenomena. By use of anatomic and physiologic techniques, the neural substrate has been shown to be notably different from that which continues to be described in textbooks, that is, the limbic system. Establishing the neurophysiologic basis for emotion has led to effective treatment for some neurologic and psychiatric disorders. Further, it has provided a basis for defining the origin of certain clinical disorders that are still obscure, the first step toward development of their specific treatment.

Animals↗