Differential roles for nicotinic and muscarinic cholinergic receptors in sustained visuo-spatial attention? A study using a 5-arm maze protocol in mice.
A 5-arm maze was used to measure sustained visuo-spatial attention in C57Bl/6 mice and test the hypothesis of differential functional roles for central nicotinic and muscarinic receptors in mediating task performance. Mice were first trained to acquire the basic visual discrimination task in which, on each trial, one randomly chosen arm among the five open arms was baited and remained lit until an arm-choice was made. Mice were then submitted to attentional testing in which trials using light signals of 2, 1 or 0.5 s were intermixed to evaluate the decrement in correct responses as a function of the decrease in light signal duration and thus, to construct a reference curve for the attentional performance of C57Bl/6 mice. Mice were then divided into four groups and received, in rotation, over four pharmacological sessions according to a Latin-square design, i.p. injections of either mecamylamine (4.0 mg/kg), scopolamine (0.8 mg/kg), the combination of mecamylamine and scopolamine or saline, 20 min before re-testing. Injection of cholinergic antagonists produced decreases in percentage of correct responses, which were systematically associated with significant increases in choice latencies. Mecamylamine produced slight disruption, whereas scopolamine and the combined treatment both produced severe disruption. In conclusion, whereas both nicotinic and muscarinic cholinergic antagonists disrupt performance in the attentional task, the increase in response latencies entails that correct responding becomes more dependent on the working memory processes and thus compromises conclusions as to a selective disruption of attention.
Leblond
Laurent
L
Laboratoire de Neurosciences Cognitives, CNRS UMR 5106, Université de Bordeaux 1, Avenue des Facultés, 33405 Talence, France.
Beaufort
Christine
C
Delerue
Fabien
F
Durkin
Thomas P
TP
D000818:Animals; D001288:Attention / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D008464:Mecamylamine / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D011597:Psychomotor Performance / Q000187:drug effects; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology; D013028:Space Perception / Q000187:drug effects / Q000502:physiology*
D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D008464:Mecamylamine; D012601:Scopolamine