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[Dendritic action potentials of pyramidal neurons of the sensomotor cortex of the cerebral cortex of the cat].

The intracellular activity of pyramidal tract neurons during electrical stimulation of ventro-lateral and ventro-postero-lateral nuclei of thalamus was studied in acute experiments on cats immobilized by myorelaxants. Both somatic and presumably dendritic spikes (d-spikes) were observed. The latter were characterized by relatively low and variable (5-60 mV) amplitude; d-spikes occurred both spontaneously and in response to single shock and tetanic (8-14/s) stimulation of the thalamus. They were also induced by intracellular depolarizing current pulses and thalamic stimulation following iontophoretic application of strychnine. Simultaneously generated somatic and d-spikes revealed no collision between each other. Intracellular hyperpolarizing current pulses abolished only somatic spikes, while d-spikes were not affected. Dendritic origin with multiple generation zones of these variable spikes is suggested. Possible functional role of d-spike is discussed.

Action Potentials↗

[Adrenal cortex transplantation. Animal experimental models for the human Cushing and Conn syndromes--clinical aspects of adrenal cortex transplantation].

Thymusaplastic mutants of mice (nu/nu) and rats (rnu/rnu) were used as recipients for tissue of one aldosteronoma of a 21-year-old male patient with Conn's syndrome and for tissue of one adenoma of a 28-year-old female patient with Cushing's syndrome. In this animal experimental study we succeeded in demonstrating that congenitally athymic rodents are ideal recipients for xenotransplantation of adrenal cortical tissue. The graft viability was demonstrated by obtaining light and electron micrographs of the biopsied transplants and its endocrine function documented by the measurements of plasma renin, cortisol, and urinary excretion of aldosterone, cortisol, and corticosterone. Fifteen patients are presented who were surgically treated for Cushing's disease. Fourteen patients with adrenocortical hyperplasia underwent total adrenalectomy and two had after adrenalectomy autotransplantation of adrenal tissue in the forearm muscle. One patient was treated with a transsphenoidal, partial hypophysectomy. Our clinical experience with Cushing's disease showed that the initial surgical procedure may be directed to the pituitary and only in unsuccessful surgery to the adrenals. Adrenal autotransplantation after total adrenalectomy is an obsolete procedure.

Adrenal Cortex↗

Largely segregated parietofrontal connections linking rostral intraparietal cortex (areas AIP and VIP) and the ventral premotor cortex (areas F5 and F4).

Two functionally different cortical areas are located in the rostral part of the intraparietal sulcus (IP): the ventral intraparietal area (VIP), along the fundus of the sulcus, and the anterior intraparietal area (AIP), rostral in the lateral bank. VIP and AIP have functional properties comparable to those of the ventral premotor areas, F4 and F5, respectively. The aim of this study was to establish whether these intraparietal and premotor areas have direct and specific anatomical connections. Neural tracers were injected in F4, F5, and AIP in three macaque monkeys. The results showed that F4 and F5 are targets of strong projections from VIP and AIP, respectively, and that the linkage between F5 and AIP is highly selective. These data support the notion that parietofrontal connections selectively link areas displaying similar functional properties and form largely segregated anatomical circuits. Each of these circuits is possibly dedicated to specific aspects of sensorimotor transformations. In particular, the AIP-F5 circuit should play a crucial role in visuomotor transformation for grasping, the VIP-F4 circuit is possibly involved in peripersonal space coding for movement.

Animals↗