HABITUATION TO SOUND STIMULATION IN DETELENCEPHALATED PIGEONS (COLUMBA-LIVIA)

Habituation to sound stimulation was analyzed in terms of the functional role of the telencephalon in learning. Sixteen pigeons were exposed to 1000-Hz, 83-dB, 1-s sound (stimulus A) at 30-s intervals until there was habituation of the exploratory and pre-exploratory responses. The learning criterion was 10 trials without the occurrence of these responses. Twenty-four hours after habituation to stimulus A the birds were tested with a 500-Hz, 85-dB, 1-s sound (stimulus B). On the day following habituation to stimulus B, the birds of the experimental group (N = 8) suffered ablation of the telencephalon and the birds of the control group (N = 8) had sham surgery. Retesting with the same sequence of procedures was carried out 10 days after surgery. In the POST-lesion situation there was a decrease of the number of habituation trials to stimulus A (P < 0.01) and to stimulus B (P < 0.05) by experimental pigeons compared to the PRE-lesion situation. The data suggest an interaction of a facilitatory effect of the lesion and long-term learning effects.