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Biomedical subjects

E Fonberg

Publications and source records attributed to E Fonberg.

At least 55 records · Page 3Linked to original sources
PubMed1974

Amygdala functions within the alimentary system.

The amygdaloid complex plays an important role in various defensive, sexual and metabolic functions of the organism. Our previous experiments on the defensive functions demonstrated that the amygdala may be divided into dorsomedial excitatory and basolateral inhibitory parts. Our recent experiments showed that this division is true also for alimentary mechanisms. The dorsomedial part of the amygdala acts as a facilitatory "center" and the lateral part as an inhibitory alimentary "center". These functions of the amygdala are parallel to those of the hypothalamic feeding centers. Bilateral damage to either the dorsomedial amygdala or to the lateral hypothalamus produced aphagia with adipsia, decrease of body weight and impairment of both classical and instrumental reactions. These changes were accompanied by low general arousal, atonia, catatonic like positions, negavitism and loss of positive emotional reactions. Damage to the lateral amygdala, on the other hand, produces a syndrome similar to damage to the ventromedial hypothalamus, i.e. hyperphagia and an increase of body weight. Slight increase of both classical and instrumental reactions and disinhibition of responses during intertrial intervals were found in both cases. Combined damage of the dorsomedial amygdala and lateral hypothalamus enhanced the symptoms attributable to each and prolonged the period of aphagia. Damage to the lateral amygdala subsequent to lesions of the dorsomedial amygdala and/or the lateral hypothalamus produced restoration of food intake, instrumental reactions and general arousal.

Amygdala↗
PubMed1973

The normalizing effect of lateral amygdalar lesions upon the dorsomedial amygdalar syndrome in dogs.

Two types of bilateral amygdalar lesions were performed successively. The first operation, involving the dorsomedial part, produced aphagia and subsequent hypophagia, vomiting and apathy. Consequently the body weight was reduced. After a few weeks partial recovery occurred. The second operation, involving the lateral part of the amygdaloid complex, produced hyperphagia, increase of body weight and restoration of general arousal. These results indicate the existence of two antagonistic systems: excitatory in the dorsomedial amygdala and inhibitory in the lateral amygdala. Damage of the inhibitory system reverses almost completely the syndrome produced by an initial lesion of the excitatory system.

Amygdala↗
PubMed1973

Salivary reactions after ventromedial hypothalamic lesions in dogs.

Lesions of the ventromedial hypothalamic nucleus produced an increase of food intake and body weight, marked augmentation of intertrial salivation, and transient disinhibition of salivation to the differentiated conditioned stimulus. It is concluded that damage of the ventromedial hypothalamic nucleus produces an increase of alimentary drive.

Animals↗
PubMed1972

Impairment of salivary reflexes after lateral hypothalamic lesions in dogs.

The effects of lateral hypothalamic lesions on salivary conditioned and unconditioned reflexes were investigated on seven dogs. Subsequent to the operation during the period of aphagia and hypophagia a total lack (6 dogs), or a decrease (1 dog) of conditioned salivary reaction was found. Strong diminution of unconditioned reactions and intertrial salivation were observed. At the end of the observation period (7 months) the conditioned and unconditioned salivary reflexes were still diminished reaching levels of 12-54 percent and 35-75 percent respectively in comparison with the pre-operative period. The mechanism of the impairment of salivary reactions was discussed.

Animals↗