Left Hemisphere-damaged Subjects Research Articles

Effects of neurological damage on production of formulaic language

Early studies reported preserved formulaic language in left hemisphere damaged subjects and reduced incidence of formulaic expressions in the conversational speech of stroke patients with right hemispheric damage. Clinical observations suggest a possible role also of subcortical nuclei. This study examined formulaic language in the spontaneous speech of stroke patients with left, right, or subcortical damage. Four subjects were interviewed and their speech samples compared to normal speakers. Raters classified formulaic expressions as speech formulae, fillers, sentence stems, and proper nouns. Results demonstrated that brain damage affected novel and formulaic language competence differently, with a significantly smaller proportion of formulaic expressions in subjects with right or subcortical damage compared to left hemisphere damaged or healthy speakers. These findings converge with previous studies that support the proposal of a right hemisphere/subcortical circuit in the management of formulaic expressions, based on a dual‐process model of language incorporating novel and formulaic language use.

Differential Processing of Implicature in Individuals With Left and Right Brain Damage

To evaluate the processing ability of implicature, especially indirect request and indirect refusal, the Four Scenes Test was administered to 20 left hemisphere damaged (LHD) subjects, 20 right hemisphere damaged (RHD) subjects and 15 normal control subjects. The results showed first, that the performance of the brain-damaged subjects was inferior to that of the control subjects in processing implicature; second, that indirect request understanding was easier than indirect refusal understanding in the brain-damaged subjects, and third that indirect refusal understanding in of the left hemisphere damaged subjects was inferior to that of the right hemisphere damaged subjects. There was no group difference in indirect request understanding though the ability of brain-damaged subjects was poorer than that of the normal controls. These findings suggest that LHD and RHD subjects were not the same in implicature processing and their responses depended on the implicature’s modularity (refusal and request).

Unilateral Brain Damage, Prosodic Comprehension Deficits, and the Acoustic Cues to Prosody

Stimuli from two previously presented comprehension tasks of affective and linguistic prosody (Pell & Baum, 1997) were analyzed acoustically and subjected to several discriminant function analyses, following Van Lancker and Sidtis (1992). An analysis of the errors made on these tasks by left-hemisphere-damaged (LHD) and right-hemisphere-damaged (RHD) subjects examined whether each clinical group relied on specific (and potentially different) acoustic features in comprehending prosodic stimuli (Van Lancker & Sidtis, 1992). Analyses also indicated whether the brain-damaged patients tested in Pell and Baum (1997) exhibited perceptual impairments in the processing of intonation. Acoustic analyses of the utterances reaffirmed the importance of F0 cues in signaling affective and linguistic prosody. Analyses of subjects' affective misclassifications did not suggest that LHD and RHD patients were biased by different sets of the acoustic features to prosody in judging their meaning, in contrast to Van Lancker and Sidtis (1992). However, qualitative differences were noted in the ability of LHD and RHD patients to identifylinguisticprosody, indicating that LHD subjects may be specifically impaired in decoding linguistically defined categorical features of prosodic patterns.

Theory of Mind and Pragmatic Understanding Following Right Hemisphere Damage

It has been maintained that 3-year-olds' difficulties in correctly predicting the undesired outcome of false beliefs reflects difficulties in interpreting the implications of conversations rather than a conceptual limitation in their theory of mind. As the right hemisphere has been seen to be responsible for the interpretation of the pragmatic aspects of communication, right-hemisphere-damaged (RHD) and left-hemisphere-damaged (LHD) adult patients in our study were compared on their ability to correctly draw inferences in false belief tasks. The RHD but not the LHD patients were found to have difficulties similar to those of young children in understanding the conversational implications of test questions. Most reported that a central story character would look for a pet in the place where it was really located instead of where the character believed it was located. However, when then asked in a control question where the pet really was, the RHD patients often switched their answer to the test question and referred to the believed location. Removal of the need to infer the questioner's meaning enabled both RHD and LHD subjects to make correct false belief predictions. The results are discussed in terms of the effects of brain damage on spatial memory and the pragmatic demands of theory of mind tasks.

Semantic attribute knowledge in adults with right and left hemisphere damage

Abstract This study investigated the nature of semantic attribute knowledge in subjects with left and right hemisphere brain damage and subjects with no brain damage. The relationship between attribute knowledge and both auditory comprehension level and naming skills was also studied. Subjects completed a sorting task involving high, mid, and low frequency of occurrence nouns and high (HI) and low importance (LI) attributes. Subjects also named pictures of the stimulus nouns. While the identification of HI attributes remained intact, left and right hemisphere-damaged subjects exhibited equivalent reductions in identification of LI attributes across frequency levels. In contrast, the left hemisphere-damaged subjects were significantly more impaired on comprehension and naming measures than were the right hemisphere-damaged subjects. Comprehension and naming performance demonstrated a systematic relationship with attribute knowledge in the left hemisphere-damaged subjects only.

Language and verbal memory after right hemispheric stroke: A clinical-CT scan study

The performances on language and verbal memory tests of 26 right-hemisphere damaged subjects (RHD) have been compared with normal controls and 11 non-aphasic left-hemisphere damaged subjects. While phonological and syntactic performance was unimpaired, a small subgroup of RHD patients, with CT scan evidence of subcortical lesion, was mildly impaired in naming tasks. The performance of RHD patients on free recall was characterized by a reduced recency effect. The implications of these findings for theories about the participation of the right hemisphere in linguistic functions are discussed.

Isolated and Sequenced Oral Motor Posture Production Under Different Input Modalities by Left-Hemisphere Damaged Adults

The purpose of this investigation was to use a well-refined system of oral movement notation to examine whether the quality of performances for production of elemental oral motor postures as isolated targets was similar to performances of the same postures produced as members of a sequence by left-hemisphere damaged (LHD) and normal adults. The effect of input modality was also examined using three conditions - imitation, photograph and command. Result suggested that “additional movements” and “errors of spatial alignment” prominently characterized both isolated and sequenced postural production errors made by both LHD and normal adults. The frequency of occurrence of these behaviours, however, was dramatically higher among the LHD subjects. Moreover, the quality of productions of oral postures deteriorated in sequences of increasing length among the LHD subjects but not among normal adults. No differential effect for mode of input was found for the LHD subjects but was for the normal adults. Results suggested that the inferior performances of LHD subjects on isolated gesture production are due to exagerrated augmentations and spatial targeting deficits. Sequence production was affected negatively by the same behaviours as well as a disability for “phasing” subcomponents of discrete movements as reflected by a significant increase in “complex” errors on the individual gestures comprising the sequence.

Effects of unilateral brain damage on contralateral and ipsilateral upper extremity function in hemiplegia.

This article describes the long-term effects of unilateral penetrating hemispheric lesions on contralateral and ipsilateral upper extremity motor performance and functional outcome. Activities-of-daily-living skill and gross motor performance contralateral to the lesions were compared among 32 left-sided and 19 right-sided hemiplegic subjects using analysis of variance and chi-square techniques. Ipsilateral to the damaged hemisphere, fine motor tasks of simple visual motor reaction time, grip and pinch strength, finger tapping, and Purdue Pegboard performance were tested. Analysis of covariance compared each ipsilateral task to performance in the corresponding hand of 70 matched controls. Results indicate similar long-term functional ADL outcome in right and left hemisphere-damaged subjects, despite more severe contralateral functional motor deficits following lesions of the left hemisphere. Right hemisphere lesions led to ipsilateral decrements in reaction time, and lesions of either hemisphere diminished grip or pinch strength, finger tapping, and pegboard performance ipsilaterally. These results demonstrate that unilateral brain damage involving the motor areas of either hemisphere has detrimental effects on ipsilateral upper extremity motor function. Findings are discussed and related to the concept that the left hemisphere is specialized or has greater neuronal representation for bilateral motor processes. Physical therapists involved in the treatment of patients with hemiplegia should be aware that motor functions of the ipsilateral, nonparetic upper extremity may also be affected adversely by unilateral brain lesions.

Contextual mood priming following left and right hemisphere damage

This research examined the influence of mood-congruent and mood-incongruent contexts on recognizing affective prosody after brain damage. Predictions stemmed from an associative network theory of learning and memory. Thirty-three male subjects, 11 each in right hemisphere damaged (RHD), left hemisphere damaged (LHD), and normal control groups judged moods from the prosody of semantically neutral phrases. In one task, the prosodic stimulus phrases were judged in isolation. In another task, the phrases were preceded by short paragraphs which were either congruent or incongruent in emotional tone with the prosodic stimuli. These paragraphs were designed to prime specific mood choices. As anticipated, LHD subjects' prosodic mood recognition was more accurate when given congruent rather than incongruent affective contexts. Congruent contexts facilitated, and incongruent contexts disrupted, their prosodic mood judgments to the same extent as normals. RHD subjects showed a partial context decrement. They were less accurate than normal or LHD subjects in the congruent condition, and were unaffected by incongruent contexts. When given congruent biasing paragraphs, however, RHD subjects did experience facilitation on a par with that found for the other groups, indicating spared sensitivity to certain contextual factors. The distinction between automatic and effortful processes is offered as a potential explanation for the RHD group's pattern of performance.

Symbolic and affective non-verbal deficits in left- and right-hemisphere injured adults

Abstract Two groups of unilaterally brain-damaged adults and a normal control group were compared on tasks of symbolic (pantomime) and affective (gesture) non-verbal communicative abilities in an attempt to correlate non-verbal communicative abilities with site of lesion. Data analysis revealed that left-hemisphere damaged subjects exhibited greater deficits in symbolic non-verbal behaviour compared to those with right-hemisphere damage and normal controls. The right-hemisphere damaged subjects demonstrated greater affective non-verbal impairment than those with left-hemisphere damage and normals, but the differences between right-hemisphere damaged subjects and left-hemisphere damaged subjects on affective mean rank scores were small. Lesion location either anterior or posterior to the Rolandic fissure did not differentiate between receptive versus expressive non-verbal abilities.

Some Effects Of Stimulus Presentation Rate and Complexity on Perception and Retention in Brain-Damaged Patients

The short term memory recall performance of 36 brain-damaged subjects was compared with the performances of 36 mentally retarded subjects and 36 normal control subjects for both total responses correct and for order errors. Stimuli were presented to all subjects at three rates, 40, 60 and 120 significant units per minute, and at three levels of stimulus concept complexity, simple, compound, and complex, at each rate. While the brain-damaged subjects perform at a slightly lower level than normal control subjects, the pattern of their performance was similar to that of the control group and showed significant differences from the performance patterns of the mentally retarded group. The brain-damaged group did not make significantly more order errors than the normal control subjects, suggesting that their organization processes for stimuli icould “keep up” with the input of their reception processes. This was not true for the retarded who made significantly more order errors than both braindamaged and normal subjects under all conditions. A comparison of small groups of left and right hemisphere damaged subjects disclosed no differences in their ability to recall aurally perceived verbal material. The incidence of order errors was not related to Verbal IQ. Correlations were made of scores obtained from subjects on a memory test for visually perceived designs and the incidence of mirror-image errors with verbal memory and verbal order error scores. Mirror-image error scores were significantly and positively related to verbal order scores for the right hemisphere damaged subjects. This relationship did not exist between the scores for the left hemisphere damaged subjects.