Impact of generalized brain arousal on sexual behavior

Abstract

Although there is an extensive amount known about specific sensory and motor functions of the vertebrate brain, less is understood about the regulation of global brain states. We have recently proposed that a function termed generalized arousal (Ag) serves as the most elemental driving force in the nervous system, responsible for the initial activation of all behavioral responses. An animal with increased generalized CNS arousal is characterized by greater motor activity, increased responsivity to sensory stimuli, and greater emotional lability. Implicit in this theory was the prediction that increases in generalized arousal would augment specific motivated behaviors that depend on arousal. Here, we address the idea directly by testing two lines of mice bred for high or low levels of generalized arousal and assessing their responses in tests of specific forms of behavioral arousal, sex and anxiety/ exploration. We report that animals selected for differential generalized arousal exhibit marked increases in sensory, motor, and emotional reactivity in our arousal assay. Furthermore, male mice selected for high levels of generalized arousal were excitable and showed more incomplete mounts before the first intromission (IN), but having achieved that IN, they exhibited far fewer IN before ejaculating, as well as ejaculating much sooner after the first IN, thus indicating a high level of sexual arousal. Additionally, high-arousal animals of both sexes exhibited greater levels of anxiety-like behaviors and reduced exploratory behavior in the elevated plus maze and light-dark box tasks. Taken together, these data illustrate the impact of Ag on motivated behaviors.anxiety | behavioral genetics | generalized arousal | male sexual behavior O ne of the basic challenges facing all vertebrate animals is the necessity to activate large numbers of behavioral responses to large numbers of environmental conditions, some of which are threatening. We have recently proposed (1) that a function exists in vertebrate nervous systems that initiates behavioral activation of large numbers of responses to meet this basic challenge, a function we have termed generalized arousal. Neurons serving generalized arousal mechanisms would receive sensory inputs both from the external environment and the internal milieu and be able rapidly to activate arousal states that empower more specific, motivated behavioral responses. An increase in activity of this system would elevate generalized arousal, producing an animal with more motor activity, greater sensory responsiveness, and increased emotional lability. The purpose of the work reported here was to add to the evidence that a generalized arousal function exists (by beginning the breeding of high and low arousal lines of mice) and to test the impact of high or low generalized arousal states on specific motivated behaviors: male sexual behavior and anxiety/exploration.So far, the existence of generalized arousal as a measurable and physiologically-relevant CNS state has been inferred from three sepa...

Quantitative descriptions of generalized arousal, an elementary function of the vertebrate brain

“…In the breeding experiment, we found that high levels of GA, as bred, had a significant impact on male sex behavior. The high-arousal male mice exhibited greater excitement and premature mounts in the presence of a receptive female and, having achieved an intromission, ejaculated significantly sooner (4). Additionally, high-arousal animals of both sexes exhibited greater levels of anxiety-like behaviors and reduced exploratory behavior in the elevated plus maze and light-dark box tasks.…”

“…With each generation, we expect the two lines to diverge if there is, in fact, a genetic basis for GA. We note that one cannot breed for a function that does not exist, and thus our success so far offers independent evidence for GA. Success so far, through generation 7, in this breeding program has recently been reported (4), showing that animals bred for high arousal have significantly greater measures in our GA assay than animals bred for low arousal.…”

Motivated state control in larval zebrafish: behavioral paradigms and anatomical substrates

“…The existence of a generalized arousal state has been inferred from a statistical factor that accounts for a substantial fraction of the variability in spontaneous locomotion and sensory responsiveness in mice during different arousal experiments (Garey et al, 2003), as well as from the success of selective breeding in generating high and low arousal strains of mice (Weil et al, 2010). A difficulty with this concept is the considerable evidence, as outlined above, that changes in sensory responsiveness are often highly selective, confined to a single ethologically relevant modality.…”

RNA interference of gonadotropin-inhibitory hormone gene induces aggressive and sexual behaviors in birds

“…It was recently proposed that generalized arousal of the central nervous system (CNS) underlies specific motivated behavior such as aggressive and sexual behaviors [39,61]. An animal with a greater degree of CNS arousal (1) shows greater responsiveness to sensory stimuli in all sensory modalities; (2) emits more motor activity; and (3) is more reactive emotionally [40].…”