1632 



HANDBOOK Ol- I'inslol OOY 



NEUROPHYSIOLOGY III 



I. VISUAL 



2. VISUAL -POSTURAL 



fic. 25. Diagrams of four experiments on spatial localization. 

 Two of these experiments (the visual-postural and visual-visual 

 tasks) have been shown to yield differential results after frontal 

 and posterior brain lesions in man. On the first and fourth tasks 



isual, postural) , normal adults and adults with frontal or parie- 

 tal lesions perform in similar fashion, all three groups can set a 

 luminous line to the vertical with very little error as long as 

 they are upright (Experiment 1), and all three make similar 

 errors in bringing themselves back to a vertical position after 



11 j ing periods in a chair tilted 30 to right or left (Experiment 

 j). However, if required to set a luminous line to the apparent 

 vertical with body tilted {Experiment 2), the frontal group makes 

 greater errors than the other two (in tin- direction opposite their 

 body tilt 1. In the third experiment, a black thread has to be set 

 to the apparent vertical against an interfering background with 

 oblique stripes and the body is kept upright. In this situation, 

 the men with posterior brain lesions make much larger errors 

 (in the- direction of the stripes 1 than the controls or the men 

 with frontal lesions [From Teuber sV Mishkin (478).] 



■ 1 ,, 1 1 1 - I >isorders in finding one's way about, even 

 in Familiar surroundings, and difficulties with dressing 

 and with the verbal distinction of various bod) 

 parts, .ill have been described as representing more 

 or less specific types of agnosia or apraxia. Experi- 

 mental analysis of these troubles (especially in their 

 more subde manifestations) suggests thai these 

 clinical designations ma\ be misleading, Thus, 

 disorders of route-finding are proabaly not a 'visuo- 

 s|>. iii.il agnosia, 1 since the disorder is .is greal or 



ltd when vision is excluded from die l.isk (see 

 fig. 26, 27). 



The task employed series of maps, presented 

 through die sense of sight or touch I 1 18 I I he subjects 

 had to follow by locomotion routes laid oul on these 

 maps (see fig 26 Errors in route-finding, under 

 these conditions, were maximal in a group of men 



TACTUAL MAPS ( CONTRALATERAL HAND ) 



fig. 26. Diagrams of maps used in route-finding test The 

 nine dots in each map represent nine circular red dots painted 

 on the floor of a large room. In the room, adjacent dots are 

 137 cm apart, center to center. The subject is given each map 

 in turn, in the order shown in the figure, and required to walk 

 through the indicated path. The tactual maps are presented to 

 the hand on the side of the brain injury (ipsilaterali or opposite 

 the injury (contralateral); these tactual maps consist of string 

 and tacks and are carried by the subject in a small curtained 

 box which permits palpation but excludes vision, [from 

 Semmes et al. (418).] 



MEAN SCORES BY GROUPS, ALL MODES COMBINED 



15 20 25 30 



MEAN SCORE 



35 



in: 27 Results nl route-finding tests. jumped according to 

 location of cerebral lesions. 1 In score indicates the number of 

 correct nuns I In- scores for the group with parietal lesions 

 .nut for that group iinl\ are significantly below the scores 

 e. lined by all other subjects, and in .ill other groups with 

 injuries to the brain in the regions Indicated (frontal, temporal, 



I'll. if. I'll and right refer to men with lesions involving the 



lill .mil right cerebral hemisphere, respectively, from Semmes 

 ,t al. (418) 



