Arousal

Neuropsychology
Topics Brain regions Clinical neuropsychology Cognitive neuropsychology Cognitive neuroscience Dementia Human brain Neuroanatomy Neurophysiology Neuropsychological assessment Neuropsychological rehabilitation Traumatic brain injury
Brain functions Arousal Attention Consciousness Decision making Executive functions Natural language Learning Memory Motor coordination Perception Planning Problem solving Thought
People Alan Baddeley Arthur L. Benton David Bohm Antonio Damasio Phineas Gage Norman Geschwind Elkhonon Goldberg Patricia Goldman-Rakic Donald O. Hebb Kenneth Heilman Eric Kandel Edith Kaplan Muriel Lezak Benjamin Libet Rodolfo Llinás Alexander Luria Brenda Milner Karl H. Pribram Pasko Rakic Oliver Sacks Mark Rosenzweig Roger W. Sperry Hans-Lukas Teuber Henry Molaison ("H.M.", patient) K.C. (patient)
Tests Benton Visual Retention Test Continuous Performance Task Halstead-Reitan Neuropsychological Battery Hayling and Brixton tests Lexical Decision Task Luria-Nebraska neuropsychological battery Mini–mental state examination Rey–Osterrieth complex figure Stroop Test Wechsler Adult Intelligence Scale Wechsler Memory Scale Wisconsin Card Sorting Task
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Arousal is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire, mobility, and reactivity.

Arousal is mediated by several neural systems. Wakefulness is regulated by the ARAS, which is composed of projections from five major neurotransmitter systems that originate in the brainstem and form connections extending throughout the cortex; activity within the ARAS is regulated by neurons that release the neurotransmitters norepinephrine, acetylcholine, dopamine, serotonin and histamine.

Activation of these neurons produces an increase in cortical activity and subsequently alertness.

Arousal is important in regulating consciousness, attention, alertness, and information processing. It is crucial for motivating certain behaviours, such as mobility, the pursuit of nutrition, the fight-or-flight response and sexual activity (the arousal phase of Masters and Johnson's human sexual response cycle). It holds significance within emotion and has been included in theories such as the James–Lange theory of emotion. According to Hans Eysenck, differences in baseline arousal level lead people to be extraverts or introverts.

The Yerkes–Dodson law states that an optimal level of arousal for performance exists, and too little or too much arousal can adversely affect task performance. One interpretation of the Yerkes–Dodson Law is the "Easterbrook cue-utilisation hypothesis". Easterbrook's hypothesis suggests that under high-stress conditions, individuals tend to focus on a narrower set of cues and may overlook relevant information, leading to a decrease in decision-making effectiveness.