Novel objects in a holeboard probe the role of the locus coeruleus in curiosity: support for two modes of attention in the rat.
Idazoxan, an alpha 2 adrenoceptor antagonist (2 mg/kg), enhanced novel object investigation in a holeboard in rats as previously reported (V. Devauges & S. J. Sara, 1990). Two weeks of 10 min/day in 37 degrees C water increased dopamine-beta-hydroxylase staining density in the locus coeruleus but did not enhance novel object investigation. In contrast to idazoxan, however, the warm water treatment increased rearing, center entries, and activity, a pattern previously described during tonic infusion of norepinephrine into the hippocampus. Correlations among dopamine-beta-hydroxylase measures and behavior reinforced these tonic norepinephrine/behavior associations. The behavioral effects across the idazoxan and warm water experiments support G. Aston-Jones et al.'s (1999) 2 modes of attention hypothesis for locus coeruleus function: Phasic locus coeruleus activity promotes focused attention; tonic locus coeruleus activity promotes scanning attention.
Mansour
Atef A H
AA
Division of Basic Medical Sciences, Memorial University, St. John's, Newfoundland, Canada.
Babstock
Doris M
DM
Penney
Jennifer H
JH
Martin
Gerard M
GM
McLean
John H
JH
Harley
Carolyn W
CW
D000818:Animals; D001288:Attention / Q000502:physiology*; D004299:Dopamine beta-Hydroxylase / Q000032:analysis; D005106:Exploratory Behavior / Q000502:physiology*; D006358:Hot Temperature; D008125:Locus Coeruleus / Q000737:chemistry / Q000502:physiology*; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans; D014867:Water
D014867:Water; D004299:Dopamine beta-Hydroxylase