Differential patterns of performance impairment result from changed reinforcer efficacy or distracting stimulation in a two-choice rodent spatial signal detection task

Measures of the discriminabililty of stimuli in signal detection tasks can be influenced by alterations of motivational state. In the present study, r ats performed an operant signal detection procedure that required the compl etion of a fixed number of responses before a stimulus was presented at one of two front cue lamps to separately measure the motivation to respond fro m the ability to respond accurately. One manipulation, presession water acc ess, affected the speed and frequency that trials were initiated, but did n ot affect response accuracy. In contrast, a flashing houselight during the session, and i.p. ((5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d,] cyc lohepten-5,10-imine (dizocilpine or MK-801), a glutamate N-methyl-D-asparta te receptor antagonist, impaired response accuracy in a stimulus duration-d ependent manner. These results suggest that it is possible to procedurally isolate the motivation to respond to stimuli from accuracy of detection, an d thereby protect attending from side effects of drugs that influence the m otivation to respond. (C) 2001 Published by Elsevier Science B.V.