Psychophysical method for mapping behavioral substrates using a moveable electrode.

With the use of moveable electrodes, 28 rat mesencephalic sites were examined for self-stimulation behavior (SS). The relative importance of each site in SS was established according to (1) a traditional method which consists of comparing sites based on the rates of responding (2) a psychophysical procedure based on the pulse frequency required at each site in order for the stimulation to elicit a criterion behavioral performance. It was shown that anatomical conclusions reached by the use of behavioral output procedures depend purely on the arbitrary choice of stimulation parameters. It was also demonstrated that the combination of moveable electrodes with psychophysical measurements results in enhanced mapping resolution and enables one to trace the boundaries of behaviorally relevant structures and pathways with significantly better confidence.