[The participation of the parafascicular thalamic nucleus and of the neostriatal cholinoreactive system in regulating the food-procuring reflex in rats at different stages of learning].

Effects of bilateral lesions of the thalamic parafascicular nucleus (Pf) and bilateral microinjections of scopolamine (cholinolytic) and carbacholine (cholinomimetic) into rat neostriatum on the strength of pressing the bar at different stages of acquisition of food-procuring reflex were studied in 51 rats. At the stage of training of food-procuring movements (only strong bar pressings were reinforced) without introduction of a conditioned stimulus, the Pf lesions decreased the rate of learning and increased the number of week pressings. At this stage, scopolamine neostriatal microinjections against the background of the Pf lesions increased the number of strong and did not affect the number of week bar pressings. On the contrary, carbacholine decreased the number of strong and increased the number of week pressings in comparison with the preinjection background. In the trained group of rats, at the stage of reflex restoration (strong bar pressings were reinforced only during the action of a conditioned stimulus) after the Pf destruction, the reflex restoration time depended on the level of presurgery training. Striatal scopolamine injections that primarily after surgery led to a high level of correct reflex realization induced a sharp impairment in reflex performance on a microinjection day, and carbacholine microinjections against the background of low reflex performance did not change this level after surgery.