P. Faglioni

The Comparative Efficiency of Intelligence and Vigilance Tests in Detecting Hemispheric Cerebral Damage

Summary The application of vigilance tests to cases of focal lesions has been investigated in brain-damaged (N: 166) and control patients (N: 139). The performances of the subjects on an intelligence test (Ravens Matrices, 1938) and in two vigilance tests (Visual Reaction Time and Continuous Choice Reaction) were compared. The two vigilance test showed greater efficiency in discriminating between normal and pathological subjects than the intelligence test, if the education level was not taken into account; this difference disappeared when specific criteria of discrimination, based on the years of schooling, were applied. The discrepancy between number of subjects classified correctly and incorrectly with the single and the specific threshold methods was greater with the Matrices than with the vigilance tests. The latter two tests do no differ from each other. In the comparison of aphasic versus left non-aphasic and left-sided versus right-sided patients there were no differences in the performances on Ravens Matrices. In the Continuous Choice Reaction the aphasics showed a poorer performance than the left non-aphasic, presumably because of the importance of internal verbalization for performance on this test; no difference was found between the two hemispheric groups. In Reaction Time aphasic and left non-aphasic subjects showed similar perfomances, but the right-sided patients were markedly slower than the left-sided ones. This result was interpreted tentatively as reflecting the presence of a more severe degree of cerebral damage in the right-sided group. The hypothesis is advanced that R.T. may be regarded as a measure of the severity of a lesion, unbiassed by its localization. This hypothesis raises the problem “why is the performance on Ravens Matrices of right-sided patients, who have the more severe lesions, not worse than that of left brain-damaged patients?” It is suggested as a further hypothesis that this may be due to the fact that the left hemisphere is crucial for all intellectual tasks, verbal as well as non-verbal.

Spatial Memory and Hemispheric Locus of Lesion

Corsis cube test was given to 40 control and 80 brain-damaged patients to assess the relation of different aspects of spatial memory to the hemispheric locus of lesion. Spatial span was found affected by injury producing visual field defect (VFD), regardless of the side of the lesion. Delayed reproduction of a 3 cube sequence (which was within the span of every patient) was performed more poorly by patients with right hemisphere damage and VFD than by controls. This was true whether the delay was unfilled or filled with a counting activity, the two conditions being equally effective in bringing about the inferiority of the right brain-damaged group. Learning to criterion up to a maximum of 50 trails a supraspan sequence was failed by 65% of right brain-damaged patients with VFD, a percentage significantly higher than that found not only in the control group, but also in any other brain-damaged group. These findings point to the dominant role played by the posterior region of the right hemisphere in subserving spatial memory mechanisms, especially when the acquisition of stable traces is requested.

Hemispheric Contribution to Exploration of Space Through the Visual and Tactile Modality

Summary Control and unilaterally brain-damaged patients were given two tests requiring the exploration of space through the visual and the tactile modalities. In the visual test, the patient was required to identify a number on a display board among alternatives, while in the tactile test he had to find a marble in a maze. The score was the time spent in searching for the item. On the visual test, controls performed better when the item was on the left side than when it was on the right. This “normal” left-right gradient (probably due to reading habits) was found to be significantly increased in left brain-damaged patients and reversed in right brain-damaged patients, a finding which supports the assumption that injury to one hemisphere mainly impairs the exploration of contralateral field. On the tactile test, each hemispheric group performed worse in the contralateral field. This lengthening of the searching time cannot be explained by disruption of the sensorimotor mechanism subserving space exploration and points to the impairment of a higher level ability, identifiable as the representation of contralateral space. When performance was scored in terms of failure in finding the marble within the 90 sec time limit, right hemisphere patients with visual field defects turned out to be significantly more impaired than any other brain-damaged subgroup. This finding is suggestive for the occurrence of unilateral neglect also in the tactile modality and it lends support to the hypothesis that hemi-inattention does not depend so much on perceptual and motor factors as on a mutilated representation of space.

Attentional Shift Towards the Rightmost Stimuli in Patients with Left Visual Neglect

In a search task where four letters were displayed to the right of a central fixation point, right brain-damaged patients with visual neglect showed the fastest response when the target was at the rightmost position and progressively slower responses as it moved towards the center of the display. This finding confirms Kinsbournes claim that in visual neglect an important role is played by the magnetic attraction that the extreme end of the right structured space exerts on the patients attention.

The Influence of Aphasia and of the Hemispheric Side of the Cerebral Lesion on Abstract Thinking

Summary A modified version of Weigl Sorting Test which allows 5 criteria of classification was administered to 40 control patients, 40 right brain-damaged patients, 22 left non-aphasic brain-damaged patients and 45 aphasics. The performance of the 4 experimental groups was analyzed by means of co-variance analysis, independent variables being age, years of schooling and RT. Right and left non-aphasic brain-damaged patients performed not differently from control patients on Weigl test, while the mean score of the aphasic group turned out to be about one half of that of the control group. The analysis yielded the same results also when the score obtained by the patients on a general intelligence test (Ravens P. M. 1938) was introduced as an additional independent variable. The score obtained by aphasics on Weigl test was found to correlate highly with an auditory verbal comprehension score, while no significant correlation was found between Weigl score and either a visual naming or an ideomotor apraxia score. Patients with typical “amnesic” aphasia were not found to perform the test more poorly than patients with typical Wernickes or Brocas aphasia. In conclusion, these data indicate that Weigl test is not sensitive to the presence of cerebral damage per se while it is highly sensitive to the presence of left (dominant) hemisphere lesions associated with aphasia. The evidence pointing to a specific defect of “abstract thinking” in aphasics may be interpreted as the consequence of a disruption of “inner language” in these patients; however, an alternative view may be advanced, viz., that the same areas subserving linguistic activities in the left hemisphere are also specialized in carrying out intellectual tasks of a symbolic nature.

Contrasting behavior of right and left hemisphere-damaged patients on a discriminative and a semantic task of auditory recognition.

Summary One hundred and one patients with unilateral hemispheric illness (41 right, 60 left hemisphere-damaged patients) and 49 control patients without cerebral lesions were given two non-verbal auditory recognition tasks, of which one (the Meaningless Sounds Discrimination Test) was intended to test the ability to discriminate the exact acoustic pattern of sounds, while the other (the Meaningful Sounds Identification Test) was intended to test the ability to identify the exact meaning of sounds. Patients were also given tests of visual discrimination (the Profile-Front Face Test), auditory verbal comprehension (the Token Test) and vigilance (simple visual reaction times). It was found that the right hemisphere-damaged patients were specifically impaired on the Meaningless Sounds Test, while the left hemisphere-damaged were specifically impaired on the Meaningful Sounds Test. This “double dissociation” was found to be highly significant. The Meaningless Sounds Test behaved like the visual discrimination test with respect to the side of the lesion, but, unlike this, it was not sensitive to the presence of homonimous visual field defects. Variations of vigilance apparently had no differential influence on the auditory recognition performances. Impairment on the Meaningful Sounds Test in left hemisoheredamaged patients was confined to aphasics and was highly correlated with the severity of the auditory verbal comprehension defect. Patients whose auditory recognition defect was strictly confined to either the Meaningless or the Meaningful Sounds Test were singled out. All 8 patients in the former group suffered from lesions of the right hemisphere and all 22 patients in the latter group suffered from lesions of the left hemisphere and aphasia. The former were significantly more impaired than the latter on the visual discrimination task, while the reverse occurred with tasks implying the semantic decoding of visual stimuli and with Weigl’s test of conceptual thought. The implications of these findings are discussed.

Performance of Left Brain-Damaged Patients on Imitation of Single Movements and Motor Sequences. Frontal and Parietal-Injured Patients Compared

The aim of this study was to investigate the relation of apraxia to the sequential features of the motor task required and to the intra-hemispheric locus of lesion. A single movement and a multiple movement imitation test were given to 60 control patients and 60 left brain-damaged patients, among which patients with frontal and parietal lesion were identified, based on CT scan evidence. Both groups performed the tasks using the left limb. On either test left brain-damaged patients scored poorer than controls and parietal patients were significantly more impaired not only than controls, but also than frontal patients. Seventy five per cent of them performed lower than the poorest control patient. In comparison, the severity and the frequency of the motor deficit following frontal damage was much lower. In no case was there a significant difference between the discriminating power of the single movement test and of the sequence test. These findings suggest that the left parietal lobe has a leading role in motor planning and that the control it exerts over the motor cortex of the right hemisphere does not necessarily involve pathways running through the left premotor area.

Recognition of random shapes by patients with unilateral lesions as a function of complexity, association value and delay.

Summary The performance of unilateral brain-damaged patients was investigated in simultaneous and delayed recognition of random shapes with two levels of complexity and association value. Left brain-damaged patients obtained lower scores than right brain-damaged patients. The impairment of left brain-damaged patients was greater in the recognition of complex patterns and in the delayed recognition of low association value random shapes. The interpretation is suggested that the meaningful identification of nonsense patterns, which favors their recognition, is impaired as a consequence of left hemisphere lesions.

Space exploration with and without the aid of vision in hemisphere-damaged patients.

Space exploration carried out under visual control and in its absence (blindfolded condition) was investigated in 20 RBD patients, 10 LBD patients and 20 normal controls with a modified version of Chedrus test (pressing the keys of a keyboard). Conventional tests for visual hemi-inattention permitted to classify RBD patients in a group with visual neglect (RBD VN+) and a group without visual neglect (RBD VN-). On the visual version of the test both RBD groups showed a preference for pressing the keys ipsilateral to the lesion side, but this tendency was more marked in the RBD VN+ group than in any other brain-damaged group. On the tactile version of the test only RBD VN+ patients showed a gradient favouring the pressing of the ipsilateral half of the keyboard. This ipsilateral preference was, however, significantly less marked than that found when the performance was assisted by vision. No relation between neglect in the blindfolded condition and tactile extinction was found. The nature of space exploration in the absence of vision is discussed and the existence of tactile neglect is questioned.

The Influence of Sex and Age on the Incidence and Type of Aphasia

The relation of sex and age to the incidence and type of aphasia was investigated in 200 aphasic patients. The following conclusions were drawn: (1) Males and females show language disorder with equal frequency. (2) There is a prevalence of non-fluent aphasics in males as compared to females. (3) Brocas aphasics are mildly, but significantly young than Wernickes aphasics.