Making associations: is the pedunculopontine tegmental nucleus involved in learning about the outcomes of actions? (360G-Wellcome-081128_Z_06_Z)

We will test the hypothesis that the pedunculopontine tegmental nucleus (PPTg)is critically involved in establishing associations between actions and their consequences. A series of experiments from this laboratory strongly suggests that the PPTg is involved in this. We will (i) examine whether the PPTg is critically required when associations are being made (when an action has low outcome predictability) but not once associations are established (when an action has a predictable outcome). (ii) Define the nature of PPTg involvement with associative learning: is it involved with action-outcome associations (subject, for example, to reinforcer devaluation), habit formation (a stimulus-response process insensitive to reward changes) or the effort required to respond? (iii) Test the hypothesis that separate parts of the PPTgare differentially involved in this. (iv) Examine the involvement of the PPTg with these processes using immediate early gene expression, and to examine theimpact PPTg lesions has on other neural systems engaged with them. The hypothesis that PPTg processes incoming data to enable selection of