This study analysed the effect of the intracerebroventricular administration of bombesin (BN) at doses of 0.001, 0.005, 0.1 and 1.0 microg/2 microl on yawning, grooming and other behavioral correlates in two inbred strains of male rats. These were selected for high-yawning (HY) and low-yawning (LY) frequency, a difference that correlates with novelty-induced grooming. Grooming increased with BN...

Yawning is a common phenomenon that is an expression of certain physiological and psychological states, yet it bas received remarkably little attention in the medical literature. Dumpert (1921), Hauptmann (1920), and Lewy (1921) reached some conclusions regarding the nature of yawning in connection with observations of patients with encephalitis lethargica; however, after the 1920s the subject ...

Objective: Crocin and safranal, as the major constituents of saffron, have many biological activities. This study investigated the effects of crocin and safranal on yawning response induced by intracerebroventricular (i.c.v.) injection of histamine in rats. Materials and Methods: In ketamine/xylazine-anesthetized rats, a guide cannula was implanted in the right ventricle of the brain and yawnin...

Yawning and spontaneous blink rate (SBR) are two physiological reflexes which have been incompletely examined but one neurobiological step of these two behaviours seems, at least in part, dopamine-dependent. The reference dopaminergic agonist, apomorphine hydrochloride (0.5, 1, and 2 micrograms kg-1 s.c.), was compared with a placebo in a double-blind latin-square design, and was shown to induc...

Yawning is a phylogenetically old behaviour that can be observed in most vertebrate species from foetal stages to old age. The origin and function of this conspicuous phenomenon have been subject to speculations for centuries. Here, we review the experimental evidence for each of these hypotheses. It is found that theories ascribing a physiological role to yawning (such as the respiratory, arou...

The dopamine (DA) D3 receptor (D3R) has been associated with impulsivity, pathologic gambling, and drug addiction, making it a potential target for pharmacotherapy development. Positron emission tomography studies using the D3R-preferring radioligand [(11)C]PHNO ([(11)C](+)-propyl-hexahydro-naphtho-oxazin) have shown higher binding potentials in drug abusers compared with control subjects. Prec...

Yawning is a phylogenetically old, stereotyped event that occurs alone or associated with stretching and/or penile erection in humans, in animals from reptiles to birds and mammals, under different conditions. Several neurotransmitters and neuropeptides are involved in its control at the central level. One of these at the level of the paraventricular hypothalamic nucleus (PVHN) is nitric oxide ...

In humans, the susceptibility to yawn contagion has been theoretically and empirically related to our capacity for empathy. Because of its relevance to evolutionary biology, this phenomenon has been the focus of recent investigations in non-human species. In line with the empathic hypothesis, contagious yawning has been shown to correlate with the level of social attachment in several primate s...

Despite the fact that yawning is a reality of everyday life, its study is not included in the curriculum of medical schools, and most medical textbooks barely mention its existence. Two factors may help to explain this puzzling situation: (a) yawning's borderline position between psychology and neurology, and (b) researchers' lack of understanding as to why people yawn. After review of the lite...

INTRODUCTION The motor pattern 'yawning' has been described for all vertebrate groups. The most intensive study of this behaviour pattern has been made by SAUER & SAUER (1967) in the South African Ostrich. They suggest that yawning assists in the regulation of the physiological state of these birds. It is primarily released and activated by endogenous stimuli, but can also be facilitated and tr...