ROBERT GALAMBOS 237 



of reach of the animal). It is evident, therefore, that the CS can evoke a 

 lar^e or a small response from the brain of a conditioned annual depending 

 on the kind of trainnig he has received. This fict may explain the varia- 

 tions in results obtained by others using this method of study (Kogan). 



HABITUATED REINFORCED WITH PUFF OF AIR 



TRIAL 12 13 5 7 



MDBRAIN (MCHTERCV) ^^ j^ , ■ __ 



yEO«»L KiiiajL«TE \r\ / I, 'J , 



M-335 3-11-58 I 1 



EXTINCTION 



T.'^IAL 9 10 34 35 61 62 



S/,A^V<'^^'"ly^vVf^'^/ V'^'"'^ ■'''*^'''' I V^"^''*' '/'^''"V ,' v'"'''"''^"^ W U Z'*'^' WV'* V*'"^ 



«-V.-^/lyWV"^^i/^*V v-v^-S'.'>y""^V.v''^^i/'^'>^, '>''•'^''M/'A.;.^^AAv,,Wy/^^ 



^.1»»VW-,,\,,WW>ny'i«.w/VWVw*JkV»* iV»'^v^^n/^'VW^'Vi^;,\/V^Wv ,i|V->*K^«VAjv*V^/--'^/'>^//^'^ 



EXTINCTION REINFORCED 



TRIAL ec 87 95 ONCE 95 I 2 



Fig. I 

 Effect of classical conditioning procedure on amplitude and duratum tit response evoked by 

 click. Rhesus monkey, chronic bipolar electrodes implanted in four brain areas as indicated. 

 The fifth line in each record signals delivery of acoustic click whose intensity remained 

 constant throughout. Record to be read from left to right, and top to bottom. In Habituated 

 Trials (i, 2) the click evoked small modest responses at all electrode locations. Effect of 

 reinforcing click with puff of air to face is to increase amplitude and duration of click response 

 in all brain loci. After discontinuation of reinforcement (E.xtinction Trial) response amplitvides 

 and durations decrease progressively until they revert (Trials 87, 95) approximately to control 

 values. A single reinforcement (96) restores response amplitude once more (i, 2). 



4. There arc many subcortical areas in which remarkably sinnlar 

 activity is aroused by both visual and auditory CSs after their reinforce- 

 ment. This is in contrast to the well-known fact that in certain regions 

 (e.g. the classical visual cortex) only one of the stimuli proves effective. 

 Brain locations where a common event is produced by different sense 

 modalities in learning situations include midbrain reticular and limbic 



