422 



BRAIN MECHANISMS AND LEARNING 



However, data obtained up to now show a possible difference between 

 the mechanism of attention and habituation. The latter develops slowly at 

 different levels of the specific pathway (Lifschitz, Palestini and Armengol, 

 1959), lasts for hours and even for days (Hernandez-Peon, Guzman, 

 Alcaraz and Fernandez-Guardiola, 1958) and is generally accompanied by 



HABITUATION 

 NORMAL CAT 



1U FLASHES 



PRETRIGEMINAL CAT 



1i» FLASHES 



AFTER 2240 FLASHES 



Fig. 4 

 Lack of habituation of secondary cortical photic potentials in inidpontine pretrigemiiial 



preparation 

 EEG record from gyrus lateralis anterior. Shows fast habituation in the normal cat and no 

 habituation in the MPP. Time calibration 0.5 seconds. 



a synchronized EEG record (Cavaggioni, Gianelli and Santibaiiez, 1959). 

 Attention, on the contrary, is accompanied by immediate reduction in 

 the amplitude of the potential when the animal is suddenly submitted to 

 an extra stimulation, it is a short-lived process and, tmally, goes together 

 with cortical arousal. 



