The arousal construct from a behavioral perspective: Structure, hormones and genes
While the construct of arousal has been regarded as the fundamental substrate of behavior, the structure and determinants of arousal are unclear. A review of the literature indicates a disparity between classical theories of arousal and recent physiological findings. While theorists such as Hebb and Duffy have conceptualized arousal as a unitary construct, neurological research has focused on elucidating distinct neuroanatomical pathways for individual arousal systems. Moreover, neurotransmitters, and hormones may influence specific subtypes of arousal. ^ At the same time, do such distinctions at a neurological level necessarily imply fractionation of the on a behavioral level as well? Might such distinct underlying mechanisms not function in a unified, harmonious, equilibrium, much like the components of a well-oiled machine? If so, the psychological theories of arousal and the neurological evidence would be complementary, rather than at odds with each other. ^ The purpose of this study was to address these issues. As such, comparative analysis of behavioral functioning in mice was conducted among six behavioral assays divided amongst Sensory, Motor, or Fear dimensions. Indices of acoustic and tactile startle comprised the Sensory measures. Motor behavior was assessed by home-cage exploratory activity, open-field activity, and performance on a running wheel. A fear conditioning paradigm indexed Fear. Three specific hypothesis were investigated: (1) Arousal functions on a behavioral level as a fractionated construct. Therefore, arousal measures will group into three independent factors, namely Sensory, Motor, and Fear. (2) Thyroid hormone will increase, and estrogen will decrease, performance in each factor. (3) Hormone receptor knock-out mice should demonstrate syndromes characteristic of deficiencies of the particular hormone. ^ Results indicated evidence for the existence of particular underlying arousal systems which generally conformed to a division along Sensory, Motor, and Fear dimensions. This was more clear for mice treated with T4 or EB. Furthermore, thyroid hormone treatment was found to increase arousal behaviors, and estrogen was demonstrated to engender behavioral calming. This pattern of results was proposed to match-up with models of human temperament. Finally, mice missing the gene for the ERα receptor were more active, and mice lacking TRβ were less active, than their wild-type controls. ^
Biology, Neuroscience|Psychology, Psychobiology|Psychology, Behavioral|Psychology, Physiological
Jonathan Steven Frohlich,
"The arousal construct from a behavioral perspective: Structure, hormones and genes"
(January 1, 2001).
ETD Collection for Fordham University.