Transfer effects and conditional learning in rats with selective lesions of medial septal/diagonal band cholinergic neurons

The authors examined visual-spatial conditional learning with automated touchscreen tasks in male Long-Evans rats with selective lesions of medial septal/vertical limb of diagonal band (MSNDB) cholinergic neurons produced by 192 IgG-saporin. Performance on a conditional task, in which 1 of 2 centrally displayed stimuli directed the rat to respond to an illuminated panel on the left or right, depended on training history: Control rats with experience on other visual tasks performed better than MS/VDB-lesioned rats with similar training histories, whereas this effect was reversed in naive rats. This difference appears to reflect transfer effects present in the control rats that are absent in the MS/VDB-lesioned rats. These findings may suggest that MSNDB cholinergic neurons play a particular role in the transfer of behavioral experience and flexibility of application of behavioral rules in memory, rather than a role in conditional learning per se.