The functional value of sound and exploratory behaviour in detelencephalated pigeons

Exploratory behaviour in response to a sound previously paired to a shock was analyzed before and after massive telencephalic lesions. Six pigeons were submitted to sound shock associations, habituation tests, telencephalic lesion and habituation retesting. Eighteen birds divided into three sham-lesioned groups received sound shock pairing (Control 1), pre-exposure to sound stimulation (Control 2) or pre-exposure to electric shocks (Control 3) before the behavioural tests. The pre-surgery tests consisted of 25 1 s pulses of sound A (1000 Hz, 83 dB) or B (500 Hz, 85 dB), every 30 s. Retests took place 10 days after surgery using the same sequence of procedures. The behaviour exhibited immediately after each sound stimulation was recorded manually and on video during the sessions. Analysis of variance showed an effect of group {F(3, 20)= 13.37, p < 0.0001) suggesting that pre-exposure to tone-shock association affected the exploration in response to the sound presented in another context. The Experimental and Control 1 birds showed no robust decrease in responses during the pre-surgery sessions. Post-surgery exploration data for detelencephalated birds showed a lower level of responding (p < 0.05). These data suggest a retardation in the typical reduction of responses to recurrent stimulation and support other evidences of the potentiating effect of sound shock association on responding. They are also indicative of telencephalic modulation of exploratory behaviour and strengthen the arguments for the subtelencephalic storage of associative information concerning the functional value of acoustic stimulation.