title: D-amphetamine depresses visual responses in the rat superior colliculus: a possible mechanism for amphetamine-induced decreases in distractibility.
abstract: Amphetamines can enhance sustained attention, and reduce distractibility, in normal subjects and patients with attentional-deficit/hyperactivity disorder (ADHD). Their mechanism of action in this regard is unknown, however one possibility is that the drugs affect the superior colliculus (SC), a structure with a clearly defined role in distractibility. The aim of the present studies was to explore the effect of systemically and locally administered d-amphetamine on visual responses in the superficial layers of the SC to wholefield light flashes in the rat, using local field potential and multi-unit recording. Systemic and intra-collicular d-amphetamine both produced a dose-related depression of visual activity, which sometimes progressed to inactivation of the multi-unit response at the highest dose. As a consequence, it is possible that amphetamines enhance sustained attention, and reduce distractibility, via an action on the colliculus. A corollary of this is that collicular dysfunction may underlie enhanced distractibility in ADHD.
authors.affiliation: Department of Psychology, University of Sheffield, Sheffield, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Gowan
authors.forename: V
authors.initials: V
authors.lastname: Coizet
authors.forename: I M
authors.initials: IM
authors.lastname: Devonshire
authors.forename: P G
authors.initials: PG
authors.lastname: Overton
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003913:Dextroamphetamine / Q000494:pharmacology*; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D008839:Microelectrodes; D010775:Photic Stimulation; D051381:Rats; D013477:Superior Colliculi / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine