TEMPORO-FRONTAL DISCONNECTION IMPAIRS VISUAL-VISUAL PAIRED ASSOCIATION LEARNING BUT NOT CONFIGURAL LEARNING IN MACACA MONKEYS

Cynomolgus monkeys were tested in two computer-controlled visual assoc iative memory tasks. The monkeys chose between visual objects on a scr een by touching one. In the configural learning task one correct objec t and one wrong object were presented in each trial. Each of these two objects was composed of two coloured alphanumeric characters abutted together. The designation of the objects as 'correct' or 'wrong' follo wed a configural rule: e.g. if AB and CD are correct objects then AD a nd CB are wrong. In the paired association learning task in each trial three spatially separate objects (single alphanumeric characters) wer e presented. The central object was an instruction cue and the designa tion of the side objects as 'correct' or 'wrong' choices followed a pa ired association rule: e.g. if A, C and B are presented (C in the cent re) then A is correct and B is wrong; however, if A, D and C are prese nted then C is correct and A is wrong. Disrupting the direct cortico-c ortical interaction between the inferior temporal cortex and the prefr ontal cortex by uncinate fascicle transection led to a learning defici t in the paired association task but not in the configural task. These results suggest that the uncinate fascicle facilitates visual-visual associative learning only in the specific case where a visual object a cts as an instruction cue to guide the conditional choice of another, spatially separate object, and they support the evidence for a specifi c role of the uncinate fascicle in the learning of conditional tasks w ith visual instruction cues.