Influence of ageing and educational level on the prevalence of body-part-as-objects in normal subjects.

When pantomiming gestures to verbal command, the overall production of body-part-as-object (BPO) errors is differentially affected by age and educational level in normal subjects. The higher overall frequency of BPO with age may be related to difficulties in the inhibition of the automatic activation of tool emblems (i.e., the BPO) instead of the appropriate hand posture to hold the tool. However, all subjects are equally able to correct errors in BPO on subsequent trials, which suggests the integrity of these gestural representations. In a clinical perspective, BPO data have therefore to be considered carefully when one wants to include this error type as an indicator of limb apraxia.     

Preliminary data on classification of normal and brain-damaged elderly subjects

Abstract

Classification of “normal” or “impaired” performance using conventional neuropsychological cut-off scores was studied in a sample of 134 normal subjects, and 94 subjects with independently confirmed cerebral damage. Conventional cut-off scores misclassified a large percentage of normal subjects as impaired. Based on raw score distributions, cut-off scores were identified which markedly improved the correct classification rates for normals. Similar analyses were performed on subgroups of the samples matched for age, sex, and education. The data were discussed in regard to previous studies, directions for future research, and potential clinical impact. Caution was urged regarding the preliminary nature of the data, and the hazards inherent in relying solely on level of performance estimates.     

Use of body part as object in brain-damaged subjects

The phenomenon of body parts as object (BPO) involves patients using parts of their body to represent an intended object when required to demonstrate a particular action. The frequency of BPO in left- or right-hemisphere-damaged (LHD, RHD) and control subjects was investigated under three testing conditions: (a) verbal command, (b) imitation, and (c) handling real objects. Mean numbers of BPO responses on command differed between the brain-damaged and control groups but not between the LHD and RHD subjects. BPO responses on command can therefore no longer be considered a feature of specific brain damage. Brain-damaged subjects showed BPO responses on imitation or handling real objects. The presence of apraxia determined the presence of BPO responses during imitation in LHD but not in RHD subjects.     

Tactile exploration of space and visual neglect in brain-damaged patients

Summary A maze test of tactile scanning was used to investigate the relationship between visual neglect and the tactile modality of space exploration in 46 patients with right-sided brain damage (RBD) (20 with and 26 without visual neglect), 27 patients with left-sided brain damage (LBD) and 30 controls. Both LBD and RBD patients that were free from visual neglect more frequently used the tactile mode to explore the space contralateral to the sound hemisphere, while the RBD patients affected by visual hemi-inattention preferred tactile scanning of the left, visually neglected, half of space. Some implications of these findings are discussed. In particular, the modality-specific nature of neglect phenomena and the possibility of tactile compensation are suggested.An earlier version of this work was presented at the 7th INS European Conference, Aachen, Federal Republic of Germany, 14 June 1984     

Discrimination and identification of emotions in human voice by brain-damaged subjects

Discrimination and identification of emotions in human voice was studied in normal controls and in 4 groups of brain-damaged subjects, subdivided along the right/left and anterior/posterior dimensions. Results showed a failure of right-brain-damaged patients, the right posterior group being significantly worse than all the other groups. Qualitative differences emerged as well: both a conceptual and an acoustic deficit seem to contribute to right posterior patient performance.     

Mechanisms of visuomotor coordination: a study in normal and brain-damaged subjects

This paper reviews the role of vision in controlling pointing and reaching movements in man. Studies of visuomotor behaviour in normal subjects allow the identification of several levels for describing organization of visuomotor control. The relative contribution of central (programming) and peripheral (feedback) mechanisms; the role of the eye-head coordinated position as a reference for controlling accuracy and direction of movements; and the relative independence of input-output channels in controlling proximal and distal segments of the musculature. These levels represent a useful framework for understanding pathological disruption of visuomotor control produced by cortical lesions.     

Spatial anisotropy of saccadic latency in normal subjects and brain-damaged patients.

In the present study, reaction time of oblique and orthogonal saccades was investigated in normal subjects and in two groups of patients with right (RBD) and left (LBD) vascular cerebral lesions and no signs of spatial neglect. Clear altitudinal effects were present in each group of subjects: saccadic latencies were longer in the lower than in the upper part of the visual field for both orthogonal and oblique saccades. Asymmetry along the horizontal meridian was present only in case of right hemisphere damage. This supports the view that a lesion in the right hemisphere causes a greater deficit of visual-spatial processing than a left hemisphere lesion. A cerebral lesion in the right and/or left hemisphere produces a general slowing in the saccadic latency and a general reduction in the accuracy of saccades with respect to normal subjects performance. Further, it seems that making saccades in oblique direction reduces the general saccade efficiency.     

Contralesional neglect of constructed visual images in right and left brain-damaged patients

Patients with left- and right-hemispheric cortical lesions and right-handed control subjects were compared on a task requiring them to judge pairs of shapes as same or different. When the shapes were moved behind a narrow viewing slit, requiring the subjects to mentally construct their horizontal dimensions, patients with right-sided lesions showed relative neglect of the left sides of the shapes, while patients with left-sided lesions showed relative neglect of the right sides. Control patients showed no overall unilateral neglect. All patients exhibited contralesional neglect on this task even if they did not show visual hemineglect on more routine measures.     

A distributed network supports spatiotemporal cerebral dynamics of visual naming

ObjectiveCerebral spatiotemporal dynamics of visual naming were investigated in epilepsy patients undergoing stereo-electroencephalography (SEEG) monitoring.MethodsBrain networks were defined by Parcel-Activation-Resection-Symptom matching (PARS) approach by matching high-gamma (50–150 Hz) modulations (HGM) in neuroanatomic parcels during visual naming, with neuropsychological outcomes after resection/ablation of those parcels. Brain parcels with >50% electrode contacts simultaneously showing significant HGM were aligned, to delineate spatiotemporal course of naming-related HGM.ResultsIn 41 epilepsy patients, neuroanatomic parcels showed sequential yet temporally overlapping HGM course during visual naming. From bilateral occipital lobes, HGM became increasingly left lateralized, coursing through limbic system. Bilateral superior temporal HGM was noted around response time, and right frontal HGM thereafter. Correlations between resected/ablated parcels, and post-surgical neuropsychological outcomes showed specific regional groupings.ConclusionsConvergence of data from spatiotemporal course of HGM during visual naming, and functional role of specific parcels inferred from neuropsychological deficits after resection/ablation of those parcels, support a model with six cognitive subcomponents of visual naming having overlapping temporal profiles.SignificanceCerebral substrates supporting visual naming are bilaterally distributed with relative hemispheric contribution dependent on cognitive demands at a specific time. PARS approach can be extended to study other cognitive and functional brain networks.     

Use of visually evoked responses in evaluation of visual blurring in brain-damaged patients

Pattern visual evoked potentials were recorded in brain-damaged patients who complained of fluctuation of vision causing visual blurring. Continuous prolonged pattern stimulation revealed marked variability of P100 amplitudes. In contrast, normal subjects and brain-damaged patients who did not complain of visual blurring showed stable P100 amplitudes. Fluctuation of vision thus seems to have an electrophysiological correlate in terms of P100 amplitude lability, which can be objectively assessed by prolonged continuous recording of pattern visual evoked potentials.     

Influence of pitch tilts on the perception of gravity-referenced eye level in labyrinthine defective subjects

We investigate the role of vestibular information in judging the gravity-referenced eye level (i.e., earth-referenced horizon or GREL) during sagittal body tilt whilst seated. Ten bilateral labyrinthine-defective subjects (LDS) and 10 age-matched controls set a luminous dot to their perception of GREL in darkness, with and without arm pointing. Although judgements were linearly influenced by the magnitude of whole-body tilt, results showed no significant difference between LDS and age-matched controls in the subjective GREL accuracy or in the intra-subject variability of judgement. However, LDS performance without arm pointing was related to the degree of vestibular compensation inferred from another postural study performed with the same patients. LDS did not utilize upper limb input during arm pointing movements as a source of graviceptive information to compensate for the vestibular loss. The data suggest that vestibular cues are not of prime importance in GREL estimates in static conditions. The absence of difference between controls and LDS GREL performance, and the correlation between the postural task and GREL accuracy, indicate that somatosensory input may convey as much graviceptive information required for GREL judgements as the vestibular system.     

Characteristics of visual stimuli and naming performance in aphasic adults.

A confrontation naming task utilizing objects and pictures from the Porch Index of Communicative Ability was presented to 14 aphasic patients. Both initially correct and self-corrected naming responses were compared for the two sets of visual stimuli. In contrast to some studies that have also varied the physical characteristics of size, color and dimensionality, the present study (as well as two other studies) found no significant differences in naming performance for aphasic patients. This evidence would suggest that a choice between pictures and objects will seldom be crucial to diagnosis or therapy with aphasic naming problems.     

Anatomic dissociation of auditory and visual naming in the lateral temporal cortex

BACKGROUND AND OBJECTIVE: Visual object naming traditionally has been used to identify cortical areas essential for naming (i.e., word retrieval), and investigators have found critical naming sites in the middle and posterior temporal region in most patients. Based on clinical observation, empirical findings, and the pathophysiology of temporal lobe epilepsy, the authors hypothesized that naming sites identified from auditory cues might also be relevant, and that within the temporal region, these sites would be anatomically distinct and located anterior to naming sites based on visual cues. METHODS: Twenty patients requiring resective surgery involving the left (language dominant) temporal lobe underwent pre-resection language mapping using direct cortical stimulation. Visual and auditory naming were tested at lateral temporal sites extending from 1 cm from the anterior tip to the parietal operculum. RESULTS: Auditory naming was consistently disrupted by stimulation in the anterior temporal lobe, whereas both auditory and visual naming were impaired by stimulation in the posterior temporal region. CONCLUSIONS: This pattern may explain why word finding difficulties sometimes arise or worsen following surgical procedures in which the anterior temporal region is resected without language mapping, or when resection is based on mapping that identifies language cortex exclusively using visual tasks. These results suggest that utilization of auditory based naming tasks might improve pre-resection identification of essential language cortex during direct stimulation cortical mapping, as well as noninvasive localization of dysfunction during presurgical cognitive testing.     

Influence of visual rearrangement and visual motion on sound localization

Abnormal changes in sound localization occur during rearrangement of the visual environment and during exposure to optokinetic stimulation. In both of these situations the errors of auditory localization result from non-veridical changes in the registration of body posture.     

Assessment of cognitive asymmetries in brain-damaged and normal subjects: validation of a test battery.

A test battery designed to assess cognitive functions normally related to the left and right cerebral hemispheres was validated on 30 patients with unilateral (16 right, 14 left) lesions. The tests were preselected to reflect typical functioning of the hemispheres according to general agreement in the literature. A Cognitive Laterality Quotient (CLQ) was calculated from the difference in performance between the "right" and "left" test batteries and, therefore, reflected the relative functioning attributed to the right and left hemispheres. Using the CLQ measurement and a control group of 30 non-neurological patients matched for age and education, 28 out of 30 brain-damaged patients (93%) were categorised correctly according to side of lesion; the other two were considered to have either abnormal lateralisation (one was left handed) or asymmetrical premorbid cognitive profiles. Using only one (paired) test whose two subparts were designed to vary only slightly in task requirements to measure either right or left functioning, 29 out of 30 patients were correctly categorised. It is suggested that the concept of relative assessment of basic cognitive functions is more fruitful than general assessment of intellectual functions for use in diagnosis and rehabilitation of neurological patients or normal subjects with developmental or acquired behavioural cognitive abnormalities.     

Appreciation of emotional expressions in the visual and auditory modality in normal and brain-damaged patients

Right-handed patients with right-sided, left-sided or without brain lesions, were tested for their appreciation of pictures of faces and tape-recorded voices carrying emotional expressions. The right hemisphere group was impaired in relation to the left and normal group. On the auditory test the impaired right-sided group showed confusion of all emotional categories. On the visual test, the same patients evaluated all emotional qualities to be happy or neutral. It is suggested that different mechanisms explain these findings: one of defective perceptual analysis, prominent in the auditory test, and one of change of mood in an euphoric direction specific to patients suffering damage to the right hemisphere.