The effects of arousal on apical amplification and conscious state



Phillips W, Larkum ME, Harley CW & Silverstein SM (2016) The effects of arousal on apical amplification and conscious state. Neuroscience of Consciousness, 2016 (1), pp. 1-13.

Neocortical pyramidal cells can integrate two classes of input separately and use one to modulate response to the other. Their tuft dendrites are electrotonically separated from basal dendrites and soma by the apical dendrite, and apical hyperpolarization-activated currents (Ih) further isolate subthreshold integration of tuft inputs. When apical depolarization exceeds a threshold, however, it can enhance response to the basal inputs that specify the cell’s selective sensitivity. This process is referred to as apical amplification (AA). We review evidence suggesting that, by regulating Ihin the apical compartments, adrenergic arousal controls the coupling between apical and somatic integration zones thus modifying cognitive capabilities closely associated with consciousness. Evidence relating AA to schizophrenia, sleep, and anesthesia is reviewed, and we assess theories that emphasize the relevance of AA to consciousness. Implications for theories of neocortical computation that emphasize context-sensitive modulation are summarized. We conclude that the findings concerning AA and its regulation by arousal offer a new perspective on states of consciousness, the function and evolution of neocortex, and psychopathology. Many issues worthy of closer examination arise.

apical amplification; arousal; conscious state; context-sensitive modulation; hyperpolarization-activated currents; schizophrenia;

Neuroscience of Consciousness: Volume 2016, Issue 1

Publication date31/12/2016
Publication date online11/09/2016
Date accepted by journal08/08/2016
PublisherOxford University Press

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Professor Bill Phillips
Professor Bill Phillips

Emeritus Professor, Psychology