FUNCTIONS OF BULBO-PONTINE RETICULAR 



FORMATION AND PLASTIC PHENOMENA 



IN THE CENTRAL NERVOUS SYSTEM 



M. Palestini and W. Lifschitz 



In investigations of the pliysiology of the Reticular Formation, the 

 concept that this structure exerts a diffuse ascending and activatuig in- 

 fluence has predominated until a short time ago. Moreover, many experi- 

 mental results are interpreted as deriving from the action ot the reticular 

 formation of the brani stem considered as a functional whole. 



In this paper, our nitention has been precisely to insist that the reticular 

 formation of the brain stem has ascending influences which evoke con- 

 tradictory phenomena. Thus, we shall see that this structure has not only 

 its well-known desynchronizing action but also a synchronizing action, 

 and that it can both exert an influence by facilitating the cortical potentials, 

 evoked by sensory stmiuli and by inhibiting them. We shall discuss these 

 last functions in relation to their possible independence of the EEG 

 pattern. Lastly, we shall reler to its participation in sleep and wakefulness, 

 in habituation and attention. 



Part of this report (paragraphs A, B, C) is concerned with experiments 

 made in the midpontine prctrigeminal preparation (MPP) in the lines 

 followed by Moruzzi's school. The following paragraph contains recent 

 results obtained in our laboratory using the same preparation. 



On this occasion, we shall omit the technical data, and summarize the 

 hndings of the studies which formed the basis for this paper. The reader 

 will tind further details in the articles that have already been published. 



A. THE MIDPONTINE PRETRIGEMINAL PREPARATION AND THE SLEEP-WAKE- 

 FULNESS RHYTHM 



EEG recordings in cats with electrolytic transsections at midpontine 

 levels (Fig. i) show a low^ voltage and high frequency activity that has 

 generally been related to the waking state (Batini, Moruzzi, Palestini, 

 Rossi and Zanchetti, 1958, 1959). 



This desynchronized EEG pattern of the MPP predominates, and the 

 periods of synchronized cortical activity observed are infrequent and 

 short lived. 



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