Operant Discriminative Learning and Evidence of SubtelencephalicPlastic Changes After Long-Term Detelencephalation in Pigeons

[摘要] We analyzed operant discrimination indetelencephalated pigeons and neuroanatomicalsubstrates after long-term detelencephalation.In Experiment I, experimental pigeons withmassive telencephalic ablation and controlpigeons were conditioned to key peck for food.Successive discrimination was made underalternating red (variable-ratio reinforcement)and yellow (extinction) lights in one key of thechamber. These relations were interchangedduring reversal discrimination. The sessionswere run until steady-state rates were achieved.Experiment II analyzed the morphology of thenucleus rotundus and optic tectum in long-termdetelencephalated and control birds, using aKlüver-Barrera staining and image analyzersystem. Detelencephalated birds had moretraining sessions for response shaping andsteady-state behavior(p<0.001), higher red keypeck rates during discrimination(p<0.01), and reversal discrimination indexes around 0.50.Morphometric analysis revealed a decreasednumber of neurons and increased vascularity,associated with increases in the perimeter(p<0.001)in the nucleus rotundus. In the optictectum, increases in the perimeter(p<0.05)associated with disorganization in the layersarrangement were seen. The data indicate thattelencephalic systems might have an essentialfunction in reversal operant discriminationlearning. The structural characteristics of subtelencephalicsystems after long-term detelencephalationevidence plastic changes thatmight be related to functional mechanisms oflearning and neural plasticity in pigeons.

[学科分类] 精神健康和精神病学