Right Hemisphere Damage Research Articles

The Temporal Organization of Affective and Non-Affective Speech in Patients with Right-Hemisphere Infarcts

To evaluate the right hemisphere's role in encoding speech prosody, an acoustic investigation of timing characteristics was undertaken in speakers with and without focal right-hemisphere damage (RHD) following cerebrovascular accident. Utterances varying along different prosodic dimensions (emphasis, emotion) were elicited from each speaker using a story completion paradigm, and measures of utterance rate and vowel duration were computed. Results demonstrated parallelism in how RHD and healthy individuals encoded the temporal correlates of emphasis in most experimental conditions. Differences in how RHD speakers employed temporal cues to specify some aspects of prosodic meaning (especially emotional content) were observed and corresponded to a reduction in the perceptibility of prosodic meanings when conveyed by the RHD speakers. Findings indicate that RHD individuals are most disturbed when expressing prosodic representations that vary in a graded (rather than categorical) manner in the speech signal (Blonder, Pickering, Heath et al., 1995; Pell, 1999a).

Age-Related Evolution of the Contribution of the Right Hemisphere to Language: Absence of Evidence

The age difference observed between Wernicke' and Broca' aphasics has been understood by some authors as an indication of a progressive diminution of the contribution of the right hemisphere to language throughout the life span. To test this hypothesis, 24 right-hemisphere-damaged (RHD) and 24 normal control adults were submitted to six tasks looking at different aspects of language abilities. Results showed that RHDs performed less well than normal subjects on 3 of these tasks, but that this difference was not linked with age (younger than 55 versus older than 65 years). Consequently, these results do not support models of functional brain organization suggesting a decreasing contribution of the right hemisphere to language abilities with age.

Process-oriented treatment of right hemisphere communication disorders.

Lacking knowledge about the cognitive processes that underlie communication impairments in patients with right hemisphere damage (RHD) and driven by increasingly limited treatment duration, speech-language pathologists often give little thought to process-oriented treatment. However, operating from a theoretical perspective in which treatment targets the processes that underlie symptoms can result in more effective treatment of a range of symptoms due to a common processing impairment. This article provides research-driven therapeutic approaches based on sound theoretical perspectives that can be combined with task-specific therapy to maximize therapeutic outcomes with this clinical population.

Sex Related Effect of Unilateral Brain Lesions on the Perception of the Mueller-Lyer Illusion

The aim of this study was to investigate the effect of unilateral brain lesions on Mueller-Lyer (M-L) illusion in the two sexes. Patients with left hemisphere (LH) and right hemisphere (RH) damage and control subjects participated in the experiment. They inspected series of M-L patterns in which the shaft with out-going fins was gradually shortened until it induced a perception opposite to the original illusion, that is, the shaft with out-going fins appeared to be shorter than the shaft with in-going fins. The subjects' task was to decide, on each trial, whether the variable shaft was longer or shorter than the other one. The point where the judgements changed from one category to the other was established using the Spearman distribution method for determining psychophysical thresholds, and was considered the measure of the strength of the illusion. The higher the value of the threshold, the stronger the illusion. Our results showed sex-related hemispheric asymmetry in subjects' susceptibility to the M-L illusion, i.e., both LH and RH lesions in females, but only RH lesions in males resulted in an increase of the strength of illusion. Moreover, males with LH lesion as well as controls partially corrected the illusory perception with practice, while both LH and RH damaged females and RH damaged males did not show this learning effect.

Analyses of Deficits in Gestural Pantomime

The frequency and characteristics of apraxia in 63 stroke patients with left- or right-hemisphere damage were examined. Analyses focussing on five dimensions of gestural performance revealed an overall frequency of apraxia of 54 % in patients with LHD and 30 % in patients with RHD. Although both groups were impaired on the orientation and hand posture dimensions of performance, the patients with RHD exhibited significantly poorer performance on the location dimension and the patients with LHD on the action dimension. Analyses of intrahemispheric lesion localization implicated damage to subcortical areas involving periventricular white matter tracts at the temporoparietal junction with apraxia.

Reliability and validity of an auditory working memory measure: Data from elderly and right-hemisphere damaged adults

The use of non-standardized measures in research and clinical assessments creates difficulties with interpretation and generalization of results obtained. One example of a widely used non-standardized tool is the reading/listening span paradigm for assessment of working memory (WM). WM is an important construct because of its purported relationship to language comprehension and capacity theories of cognition. This paper investigates several facets of reliability and validity for an auditory working memory measure designed for older adults and individuals with right hemisphere brain damage (RHD). Results from 28 non-brain-damaged subjects (NBD) and 11 RHD subjects indicate that the measure is internally consistent and reliable over time. Construct validity evidence, which compares favourably with evidence from existing literature, suggests that for NBD sujects this tool differentiates WM from simple short term memory. RHD subjects do not demonstrate the same pattern of validity results as the NBD group. Further evaluation with RHD patients is warranted, because clinically this tool may be useful as a measure of severity or a prognostic indicator of language comprehension abilities for this population.

Modulation of Covert Visual Attention by Hand Movement: Evidence from Parietal Extinction after Right-hemisphere Damage

Modulation of Covert Visual Attention by Hand Movement: Evidence from Parietal Extinction after Right-hemisphere Damage

Modulation of covert visual attention by hand movement: evidence from parietal extinction after right-hemisphere damage

Modulation of covert visual attention by hand movement: evidence from parietal extinction after right-hemisphere damage

Modulation of covert visual attention by hand movement: Evidence from parietal extinction after right-hemisphere damage

Several recent studies have reported that left visual inattention following right-hemisphere damage can be ameliorated during active movements of a contralesional limb in contralesional space, even when that limb is unseen. This apparent influence of motor activity on sensory performance is of considerable interest, both from a theoretical perspective, and also practically because of its potential implications for rehabilitation. However, the exact basis of the motoric influence has remained unclear, in part because many of the clinical tests used for visual inattention themselves involved motoric factors (e.g. exploratory eye-movements are required in typical cancellation tasks). It is therefore possible that limb activation has its effects largely through an influence on other motor systems (e.g. attracting saccades towards the active limb) rather than by directly affecting perception. Here we test in a single patient, with left-sided visual extinction following a right-hemisphere lesion, whether activation of the contralesional hand can overcome left-sided inattention in a visual task that has no spatial motor component. We conducted a standard computerized test for visual extinction (the patient verbally detected brief targets on the left, right, or both sides, while fixating centrally), with the innovation that the patient triggered each trial by pressing a key with her unseen hand. This start key was located either on the left or right, and the patient used either her left or right hand to trigger the trial. We found that left-sided visual extinction was substantially reduced when the patient used her left hand in left hemispace to start each trial. This confirms that activation of a contralesional effector in contralesional hemispace can have a direct influence on sensory visual inattention, bringing contralesional visual events back into the patient's awareness.

Comparison of Graphic Symbol Learning in Individuals with Aphasia and Right Hemisphere Brain Damage

This study compared the differences in performance on recognition of graphic symbols across time by individuals with aphasia, individuals with right-hemisphere brain damage, and neurologically normal adults. The subjects, seen individually, learned 40 Blissymbols. The symbols were selected so that the effects of symbol translucency and complexity on the recognition of graphic symbols could be examined. A paired-associate learning paradigm was used to teach the symbol–referent pairs to subjects. The results indicated that individuals with aphasia and neurologically normal adults do not differ significantly in recognition of graphic symbols. However, individuals with right-hemisphere damage recognized fewer symbols compared to individuals with aphasia and normal adults, suggesting that they have difficulty in associative learning of graphic symbols. Additionally, translucency was found to be a potent factor in the recognition of Blissymbols by all groups. The finding that individuals with severe chronic aphasia can learn and retain graphic symbols has significant clinical implications for aphasia rehabilitation.

Distinguishing Lies from Jokes: Theory of Mind Deficits and Discourse Interpretation in Right Hemisphere Brain-Damaged Patients

Right-hemisphere brain damaged (RHD) patients and a normal control group were tested for their ability to infer first- and second-order mental states and to understand the communicative intentions underlying ironic jokes and lies. Subjects listened to stories involving a character who had either a true or a false belief about another character's knowledge. Stories ended either with an ironic joke or a lie by this character. In the joke stories, the speaker knew that the listener knew the truth (a true second-order belief) and did not expect the listener to believe what was said; in the lie stories, the speaker did not know that the listener actually knew the truth (a false second-order belief) and thus did expect the listener to believe what was said. RHD patients performed significantly worse than control subjects on one of two measures of second-order belief, which suggests that the ability to make second-order mental state attributions is fragile and unreliable following right-hemisphere damage. RHD patients in addition performed worse than controls when asked to distinguish lies from jokes, confirming their known difficulties with discourse interpretation. For both groups, the ability to distinguish lies from jokes was strongly correlated with two measures of the ability to attribute correctly second-order beliefs. These results suggest that the fragility of RHD patients' understanding of second-order mental states underlies a portion of their difficulties in discourse comprehension, but that the underlying impairment is not restricted to right hemisphere dysfunction.

Informational content and unilateral neglect: A longitudinal investigation of five subjects with right hemisphere damage

The relationship between unilateral visual neglect and production of narrative discourse in five patients with right hemisphere damage (RHD) was examined longitudinally. Initially, all subjects demonstrated a left unilateral neglect on the Behavioural Inattention Test (Wilson et al. 1987a). During subsequent testing at 6–8 months and 12–16 months post-onset, subjects with a persistent unilateral neglect produced less concise discourse with reductions in the percentage of meaningful content units as compared to a group of control subjects. Subjects with a transient unilateral neglect produced informational content that was comparable to the normal subjects. Results support the notion that the presence and persistence of a unilateral visual neglect might assist in delineating more homogeneous groups of RHD subjects.

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.

Suppression and discourse comprehension in right brain-damaged adults: A preliminary report

Eighteen right-hemisphere-damaged (RHD) and 15 control subjects listened to sentences that ended in lexical ambiguities. The sentence verbs biased ambiguity interpretation. Probe words, representing unbiased meanings of the ambiguities, were presented for rapid judgements of their fit with the sentences. In rejecting probe words, both groups showed interference from unbiased meanings of the ambiguities at a short (175 ms) probe interval. Only RHD adults demonstrated interference 1000 ms after sentence offset, indicating that they suppressed contextually inappropriate meanings less effectively than control subjects. Discourse comprehension performance in RHD adults was also correlated with suppression. Theoretical and clinical implications are considered.

The Ability to Perceive and Comprehend Intonation in Linguistic and Affective Contexts by Brain-Damaged Adults

Receptive tasks of linguistic and affective prosody were administered to 9 right-hemisphere-damaged (RHD), 10 left-hemisphere-damaged (LHD), and 10 age-matched control (NC) subjects. Two tasks measured subjects' ability to discriminate utterances based solely on prosodic cues, and six tasks required subjects to identify linguistic or affective intonational meanings. Identification tasks manipulated the degree to which the auditory stimuli were structured linguistically, presenting speech-filtered, nonsensical, and semantically well-formed utterances in different tasks. Neither patient group was impaired relative to normals in discriminating prosodic patterns or recognizing affective tone conveyed suprasegmentally, suggesting that neither the LHD nor the RHD patients displayed a receptive disturbance for emotional prosody. The LHD group, however, was differentially impaired on linguistic rather than emotional tasks and performed significantly worse than the NC group on linguistic tasks even when semantic information biased the target response.

Production of affective and linguistic prosody by brain-damaged patients

To test a number of hypotheses concerning the functional lateralization of speech prosody, the ability of unilaterally right-hemisphere-damaged (RHD), unilaterally left-hemisphere-damaged (LHD), and age-matched control subjects (NC) to produce linguistic and affective prosodic contrasts at the sentence level was assessed via acoustic analysis. Multiple aspects of suprasegmental processing were explored, including a manipulation of the type of elicitation task employed (repetition vs reading) and the amount of linguistic structure provided in experimental stimuli (stimuli were either speech-filtered, nonsensical, or semantically well formed). In general, the results demonstrated that both RHD and LHD patients were able to appropriately utilize the acoustic parameters examined (duration, fundamental frequency (F 0), amplitude) to differentiate both linguistic and affective sentence types in a manner comparable to NC speakers. Some irregularities in the global modulation of F 0 and amplitude by RHD speakers were noted, however. Overall, the present findings do not provide support for previous claims that the right hemisphere is specifically engaged in the production of affective prosody. Alternative models of prosodic processing are noted.

Bridging inference and Relevance Theory: An account of right hemisphere inference

Recent research suggests that the integrity of the right hemisphere is necessary for the processing of language in context (e.g. Foldi, 1987). A specific case of such processing is the ability to draw inferences from utterances. Studies show that patients with right hemisphere damage (RHD) have reduced ability to draw correct inferences from texts (e.g. Bryan, 1989). Currently there is little agreement as to the cause of this inability. This study adopts a Relevance Theory approach (Sperber and Wilson, 1986) to create a model of utterance processing, from which the cause of difficulties with inference might be deduced. The model serves as the basis for devising 60 bridging inferences on which six RHD subjects and 12 control subjects are tested. The inferences are of three types: textual, textually reinforced and encyclopaedic. The RHD subjects in this study performed worse overall, and in addition performed differentially on the three inference types. The implications of these results are discussed in the light of Relevance Theory, and it is suggested that RHD patients' problems with inference stem from an inability to use linguistic information from the text in the deductive system, coupled with an over-reliance on encyclopaedic information.

False Recognition of Unfamiliar Faces Following Right Hemisphere Damage: Neuropsychological and Anatomical Observations

False recognition of unfamiliar faces was investigated in patients with focal right hemisphere damage (RHD) in order to define the neuropsychological and anatomical correlates of the recognition impairment and examine its relationship to prosopagnosia. Findings are discussed within the framework of the Bruce and Young (1986) model of face processing. Although false recognition and prosopagnosia were both present in some RHD patients, the two types of face recognition impairments were dissociable in others. Processing deficits in subjects with both false recognition and prosopagnosia were associated with posterior right hemisphere lesion sites and included severe face perception impairment and partial damage to face recognition units (FRUs). Prosopagnosia without false recognition was seen following near complete destruction of FRUs, but this type of dissociation could also occur when FRUs become disconnected. The opposite dissociation, false recognition without prosopagnosia, was observed following right prefrontal damage. We propose that false recognition in frontal patients results from the breakdown of strategic decision making and monitoring functions critical for determining whether a face is indeed that of a familiar person or whether there is merely a resemblance to a known individual. False recognition following prefrontal damage may also be related to confabulation, in which case familiarity or even specific identity are erroneously attributed to facial stimuli without the activation of an underlying memory representation.

Behavioral Differences in School Age Children after Perinatal Stroke

Little is known about the influence of the right hemisphere (RH) on social and emotional development in children. In order to examine the effect of RH damage on behavioral function, the Personality Inventory for Children was administered to parents of 17 children who had suffered perinatal strokes and 23 control children. Children with focal brain lesions, regardless of hemisphere, had higher T scores (indicating greater abnormality) than controls on scales measuring social competence, emotional behavior, cognitive and academic development. Children with lesions involving the frontal lobe obtained higher T scores than did those with nonfrontal lesions or controls on scales related to cognitive function. The nonfrontal group had higher T scores than those with frontal lesions on measures of social competence and behavior. The data suggest that any focal brain lesion of early onset may predispose one to social and cognitive deficits. The site of the lesion within the hemisphere may be of importance in determining what difficulties the child may experience (i.e., frontal lobe lesions are more likely to result in cognitive deficits, whereas posterior lesions are more likely to be associated with social problems). These findings further suggest that brain localization for cognitive and social skills may be determined very early in development.

The basis of hemispheric asymmetries for language and spatial cognition: Clues from focal brain damage in two deaf native signers

Abstract The existence of hemispheric asymmetries for language processing and visuospatial processing is well established. In this report we investigate the basis of these asymmetries through the window of American Sign Language (ASL). ASL uses spatial contrasts to encode grammatical information at all levels of representation, including phonology, morphology, and syntax. In addition, however, ASL uses space in an iconic fashion to represent spatial information directly, as, for example, in describing the layout of objects in a room. We tested the performance of two deaf, native signers—one with left hemisphere damage (LHD) and one with right hemisphere damage (RHD)—on tasks involving the use of space, within ASL, to represent linguistic versus spatial information. We found a double dissociation: the LHD signer was impaired on tasks involving the use of space for encoding grammatical information, but performed well on tasks involving the use of space to encode spatial information iconically; the RHD signe...