THE PATTERNING OF SKILLED MOVEMENTS 



l6 93 



psychic processes antecedent to motor behavior. 

 Lhermitte thinks that this rupture is the essential 

 source of the disorganization which underlies the 

 purest and most certain forms of ideokinetic apraxia 



(73)- 



ideational apraxia. The patients who present this 

 disorder are capable of executing upon command 

 simple symbolic gestures but cannot carry out 

 complicated acts which require the harmonious 

 succession of a series of movements. Everything 

 happens as if the patient could not represent to 

 himself exactly, in their proper order, the series of 

 gestures and movements necessary to attain a deter- 

 mined objective — for instance, to take and light a 

 cigarette or to put a letter in an envelope which he 

 must seal. The patient executes correctly each part 

 of the action but mixes them; he commits surprising 

 errors without being conscious of them, for instance 

 he scratches the cigarette against the match box. 

 Certain authors, like Morlaas (88) have, in this 

 case, spoken of an 'agnosia of use." In this kind of 

 disorder the basic disturbance seems to be con- 

 nected with a disorder of the conception oi the act. 

 The gesture cannot be comprehended according to .1 

 coherent preconceived plan. The kinetic figures, 

 although intact, are anarchically mobilized. 



It seems very difficult to attribute an accurate 

 localizing value to these disorders which are not very 

 well defined. However, it is important to emphasize 

 the deficiency of integration of the gesture in time 

 which characterizes them. The phenomena described 

 can be related to disorders of temporal seriation or of 

 anticipation observed in animals and in man after 

 lesions localized in the anterior frontal areas (39, 57, 

 1 14). 



In this connection Dal Bianco (25) introduces the 

 notion of a 'scheme of action' distinct from the body 

 scheme. This scheme implies the unification of action 

 in time: the integration of influences from movements 

 already carried out with the knowledge of those in 

 the course of execution so as to regulate by antici- 

 pation the succession of future movements necessary 

 to the pursuit of the action. The essential feature of 

 the scheme of action is therefore its temporal ordi- 

 nation of movements. 



We find here again the problem of the nature of 

 the plan of movement that is classically considered as 

 a necessary prerequisite to all volitional activity. It is 

 the esquisse idealoire of the French authors, the Be- 

 wegungsentwur] of the German authors. It supposes the 

 existence of a so-called motor image or representation 



of the movement to be accomplished. The early 

 authors assigned an essential role to these residues of 

 past acts which permit prediction of the action in its 

 smallest details and its realization in conformance 

 with the established intent. 



Wachholder (124), in his study of voluntary 

 movement, emphasizes the importance of the Be- 

 wegungsentwurf which contains potentially all the data 

 necessary for the final development of action. Schilder, 

 like Liepmann, has also postulated the presence of a 

 plan of anticipation before any movement. But this 

 plan, according to Schilder (106), is not clearly 

 represented to us. Thecpicritic components of sensory 

 information play only a secondary role. This plan in 

 its first form should be only the expression of a 

 'psychic tension' born of the representation of the 

 goal to be attained and energized by the psycho- 

 affective elements of motivation. It is an intention 

 directed towards a goal.' The conception of the proper 

 means to attain this goal is hardly conscious. The 

 early stage of the plan will develop and take form 

 through .1 process of dynamic construction in which 

 the "posuiral model" necessary lor die ad is organized 

 in the frame of the usual representation and the 

 11 inal image of the hod v. The visual elements gener- 

 ally play a determining role in the appreciation of the 

 spatial relations which precede intentional action. 

 Then, as soon as the movement is started, the move- 

 ment is performed thanks to the sensor) data born of 

 the action itself. It proceeds until the projected 

 objective is achieved under the influence of the 

 successive structurings of the plan of action. 



Psychologists have underlined the important place 

 held by the affective element, the desire or tendency 

 which favors the structuring of the intention, moti- 

 vates the incitation of the act and sustains the real- 

 ization until the final goal is achieved. The recog- 

 nition of particular disorders "I motor initiative, the 

 Antrieb of the German authors, emphasizes the role 

 which must be reserved to these basic motivational 

 factors in the starting and in the dynamic sustaining 

 of the action. We agree in acknowledging today the 

 part in these manifestations which the rhinencephalic 

 structures play in strict liaison with the anterior 

 frontal regions of the cortex (39, 84, 100). They are 

 integrated with the most general mechanisms con- 

 trolling vigilance which are resident in the reticular 

 formations of the brain stem (27, 76, 81 ). 



Finally, the study of the problem of apraxias has 

 brought up the question of cerebral dominance. The 

 inequality of use and especially of skill of the two 

 hands is well known in man where we generallv 



