Department of Psychiatry, University of Cape Town, Observatory, 7925, Cape Town, South Africa; Department of Human Biology, University of Cape Town, Observatory, 7925, Cape Town, South Africa; Department of Psychiatry, University of Cape Town, Office 105, J-2 Block Groote Schuur Hospital, Anzio Road, Observatory, 7925, Cape Town, South Africa
Howells, F.M., Department of Psychiatry, University of Cape Town, Observatory, 7925, Cape Town, South Africa, Department of Human Biology, University of Cape Town, Observatory, 7925, Cape Town, South Africa, Department of Psychiatry, University of Cape Town, Office 105, J-2 Block Groote Schuur Hospital, Anzio Road, Observatory, 7925, Cape Town, South Africa; Stein, D.J., Department of Psychiatry, University of Cape Town, Observatory, 7925, Cape Town, South Africa; Russell, V.A., Department of Human Biology, University of Cape Town, Observatory, 7925, Cape Town, South Africa
A certain level of arousal is required for an individual to perform optimally, and the locus coeruleus norepinephrine (LC-NE) system plays a central role in optimizing arousal. Tonic firing of LC-NE neurons needs to be held within a narrow range of 1-3 Hz to facilitate phasic firing of the LC-NE neurons; these two modes of activity act synergistically, to allow the individual to perform attentional tasks optimally. How this information can be applied to further our understanding of psychiatric disorders has not been fully elucidated. Here we propose two models of altered LC-NE activity that result in attentional deficits characteristic of psychiatric disorders: 1) 'hypoaroused' individuals with e.g. attention-deficit/hyperactivity disorder (ADHD) have decreased tonic firing of the LC-NE system, resulting in decreased cortical arousal and poor attentional performance and 2) 'hyperaroused' individuals with e.g. anxiety disorders have increased tonic firing of the LC-NE system, resulting in increased cortical arousal and impaired attentional performance. We argue that hypoarousal (decreased tonic firing of LC-NE neurons) and hyperarousal (increased tonic firing of LC-NE neurons) are suboptimal states in which phasic activity of LC-NE neurons is impeded. To further understand the neurobiology of attentional dysfunction in psychiatric disorders a translational approach that integrates findings on the LC-NE arousal system from animal models and human imaging studies may be useful. © Springer Science+Business Media, LLC 2012.
noradrenalin; anxiety disorder; arousal; article; attention; attention deficit disorder; human; locus ceruleus; mental performance; mental task; nerve potential; neuromodulation; nonhuman; Action Potentials; Animals; Anxiety Disorders; Arousal; Attention; Attention Deficit Disorder with Hyperactivity; Disease Models, Animal; Humans; Locus Coeruleus; Models, Neurological; Animalia