A. Zanchetti

Midbrain course of descending pathways mediating sham rage behavior

Abstract The midbrain course of descending pathways mediating sham rage behavior has been investigated in thalamic cats. Electrical stimulation of the lateral hypothalamus has been tested for rage outbursts before and following various lesions in the midbrain. The following lesions were found not to impair transmission of the descending hypothalamic influences: transection of the rostral third of the central periaqueductal gray and adjacent tegmentum, with interruption of the hypothalamic component of Schutzs dorsal longitudinal fasciculus; midline lesions, including the medial component of the medial forebrain bundle to the ventral tegmental area of Tsai and to the caudal periaqueductal gray; and lateral tegmental lesions involving the lateral component of the medial forebrain bundle to the lateral midbrain tegmentum. Large lesions involving most, though not all, of the tegmentum at the midcollicular level impaired, but did not abolish, rage responses to lateral hypothalamic stimulation. It is concluded that descending connections from the lateral hypothalamus, responsible for the peripheral manifestations of rage, are diffuse through the midbrain, including both the lateral and the medial components of the medial forebrain bundle, and possibly the dorsal longitudinal fasciculus as well.

CAROTID SINUS AND AORTIC REFLEXES IN THE REGULATION OF CIRCULATION DURING SLEEP.

In the cat with intact sinoaortic reflexes, episodes of deep sleep are accompanied by marked falls in both systolic and diastolic blood pressure. The falls are much larger after bilateral sino-aortic deafferentation: to such low pressures during deep sleep that episodes of transient cerebral ischemia (electroencephalographic flattening and seizures) sometimes occur.

Electroencephalographic Desynchronization during Deep Sleep after Destruction of Midbrain-Limbic Pathways in the Cat

Lesions which interrupt the ascending limb of the midbrain-limbic circuit in the cat at different levels, or which even destroy it completely, do not prevent electroencephalographic desynchronization at the beginning of periods of deep sleep, nor do they affect the maintenance of desynchronization throughout the sleep episodes. The pontine mechanisms responsible for these electroencephalographic patterns can apparently exert their influence through ascending pathways other than those directly impinging on the hypothalamus and the limbic system.

Spatial patterns of ventricular repolarization in arterial hypertension

Abstract 1. 1. A study of the spatial electrocardiographic patterns has been performed in patients with arterial hypertension, using Franks corrected orthogonal system, and the results obtained have been compared to the patterns characteristic of normal subjects. 2. 2. Spatial QRS- and T-vector magnitude and direction, and the angle between the two (dA°) have been measured preliminarily in normal subjects, and a definite correlation has been found to exist between spatial QRS and T magnitudes, and between dA° and T magnitude. A multiple regression equation showing dependence of T magnitude on both QRS magnitude and dA° has been calculated and the relation found highly significant. 3. 3. In hypertensive patients with no signs of altered repolarization on conventional electrocardiographic leads the most striking feature has been found to be a widening of dA° and an absent correlation between dA° and T magnitude. These phenomena are paralleled by a definite increase in ventricular gradient magnitude. Widening of dA° has therefore been assumed to represent an early sign of altered repolarization which may not be evident from qualitative evaluation of conventional leads. 4. 4. In hypertensive patients with electrocardiographic signs of overload the direction of the T vector has been found to be completely upset, so that a further widening of dA° results. Any correlation between QRS, T, and dA° magnitude is completely lost.

Regional blood flows during desynchronized sleep in the cat

Durante il sonno desincronizzato del gatto, non si ha una vasodilatazione generalizzata a tutti i letti vascolari. Mentre il distretto mesenterico si dilata, quello muscolare si costringe. La vasodilatazione viscrale dipende da una diminuita attività simpatica; per la vasocostrizione muscolare, invece, bisogna pensare, oltre che a meccanismi nervosi, anche a fattori meccanici e metabolici.

Carotid body chemoceptors: physiological role in buffering fall in blood pressure during sleep.

In cats whose aortic nerves were severed subsequent deafferentation of the carotid body chemoceptors (the carotid sinus baroceptors remaining intact) did not change arterial pressure during wakefulness or light sleep, but the falls in pressure during deep sleep were markedly exaggerated. Subsequent baroceptive denervation did not modify the hypotensive effect.

Tonic reflex regulation of the cat's blood pressure through vagal 'non-aortic' afferents

La sezione del vago cervicale, dopo precedente sezione dei nervi aortici, produce un cospicuo aumento della risposta pressoria allocclusione carotidea, o, nellanimale con denervazione seno-carotidea, della pressione arteriosa basale. Questo fenomeno non dipende dalle concomitanti variazioni respiratorie, né dalla sezione di eventuali fibre di origine aortica decorrenti nel vago.

Effects of presso- and chemoceptive components of the cat's aortic nerve on sham rage behaviour

La stimolazione elettrica delle fibre aortiche a più bassa soglia, presumibilmente dorigine pressocettiva, è capace dinibire tutte le manifestazioni somatiche e viscerali dellattività di rabbia del gatto talamico acuto. Uno stimolo maggiore, eccitando un altro gruppo di fibre, probabilmente di tipo chemocettivo, maschera questo effetto inibitorio, portando alla luce in sua vece una forte attivazione del comportamento di rabbia.

Excitation of sham rage behaviour by controlled electrical stimulation of group I muscle afferents

La stimolazione elettrica ad alta cadenza (100–600 c/sec) del puro contingente di fibre muscolari appartenenti al gruppo I è in grado di scatenare accessi di falsa rabbia nel gatto decorticato, anche dopo ablazione del cervelletto e somministrazione di curarizzanti.

Respiratory influences upon depressor and pressor responses to stimulation of the aortic nerve in the decerebrate cat

Le risposte circolatorie alla stimolazione elettrica del nervo aortico sono notevolmente modificate dalla ventilazione polmonare. In particolare le risposte a stimoli di intensità intermedia ed elevata, che attivano oltre a fibre pressocettive anche fibre chemocettive, divengono da ipotensive ipertensive durante ipoventilazione. Gli effetti dellipoventilazione sono sempre riprodotti sia dallipercapnia (respirazione con CO2 5–7% in O2) sia dallipossia (respirazione di O2 5–8% in N2).