Right Hemisphere Damaged Patients Research Articles

Metaphor Comprehension in Right Brain-Damaged Patients with Visuo-Verbal and Verbal Material: A Dissociation (RE)Considered

Metaphor comprehension was investigated in 50 right-hemisphere damaged (RHD) patients and 38 control subjects in two experimental conditions: a visuo-verbal and a verbal test. In the visuo-verbal test, subjects had to match a metaphorical sentence with one of four pictures representing the correct metaphorical meaning, the literal meaning, a control metaphor and a control literal meaning. In the verbal test, a metaphorical sentence had to be matched to a correct written metaphorical interpretation, a literal or a control interpretation. On both tests, the number of correct metaphorical responses in the RHD group was lower than in the control group. However, RHD patients performed more poorly in the visuo-verbal than in the verbal condition. Interestingly, when they selected the wrong response, the RHD patients tended to select the literal one only in the visuo-verbal condition. Context does not seem to be responsible for the dissociation between the two tests. The influence of the RHD patients' major visuo-spatial deficits was also checked, to exclude their role in the tendency to be literal with visuo-verbal material. Results are discussed in the perspective of an integration deficit.

Temporal parameters as cues to phrasal boundaries: A comparison of processing by left- and right-hemisphere brain-damaged individuals

Two experiments were conducted to examine the ability of left- (LHD) and right-hemisphere-damaged (RHD) patients and normal controls to use temporal cues in rendering phrase grouping decisions. The phrase “pink and black and green” was manipulated to signal a boundary after “pink” or after “black” by altering pre-boundary word durations and pause durations at the boundary in a stepwise fashion. Stimuli were presented to listeners auditorily along with a card with three alternative groupings of colored squares from which to select the presented alternative. Results revealed that normal controls were able to use both temporal cues to identify the intended grouping. In contrast, LHD patients required longer than normal pause durations to consistently identify the intended grouping, suggesting a higher than normal threshold for perception of temporal prosodic cues. Surprisingly, the RHD patients exhibited great difficulty with the task, perhaps due to the limited acoustic cues available in the stimuli.

A Comparison of the Comprehension of Idioms by Aphasic Patiens and Right-hemisphere Damaged Patients

A Comparison of the Comprehension of Idioms by Aphasic Patiens and Right-hemisphere Damaged Patients

Sensitivity to sub-syllabic constituents in brain-damaged patients: evidence from word games

Two experiments were conducted to examine whether left- (LHD) and right-hemisphere-damaged (RHD) patients exhibit sensitivity to sub-syllabic constituents (i.e., onsets and codas) in the generation of nonwords, using a word games paradigm adapted from Treiman (1983). Four groups of individuals (including LHD fluent and nonfluent aphasic patients, RHD patients and normal controls) were trained to add syllables to monosyllabic CVC nonwords either after the initial consonant (Experiment 1) or prior to the final consonant (Experiment 2) to create bisyllabic nonwords. Experimental stimuli consisting of CCVC or CVCC nonwords tested whether participants would preserve or split the onset and coda constituents in producing the novel bisyllabic nonwords. Results revealed that the majority of subjects demonstrated sensitivity to the sub-syllabic constituents, preserving the onsets and codas. The fluent aphasic patients exhibited a greater than normal tendency to split the onset and coda constituents; however, the small number of individuals in that group whose data met inclusion criteria limits the conclusions that may be drawn from these findings. The results are discussed in relation to theories of phonological deficits in aphasia.

Word recognition in individuals with left and right hemisphere damage: The role of lexical stress

Lexical stress patterns appear to be important in word recognition processes in normal individuals. The present investigation employed a lexical decision task to assess whether left (LHD) and right hemisphere damaged (RHD) patients are similarly sensitive to stress patterns in lexical access. The results confirmed that individuals without brain damage are influenced by stress patterns, as indicated by increased lexical decision latencies to incorrectly stressed word and nonword stimuli. The data for the LHD patients revealed an effect of stress for real word targets only, whereas the reaction time data for the RHD patients as a group showed no significant influence of stress pattern. However, there was a great deal of individual variability in performance. The latency and error rate findings suggest that LHD patients and non-brain-damaged individuals are both sensitive to lexical stress in word recognition, but the LHD patients are more likely to treat incorrectly stressed items as nonwords. The results are discussed in relation to theories of the hemispheric lateralization of prosodic processing and the role of lexical stress in word recognition.

Production of Stress Retraction by Left- and Right-Hemisphere-Damaged Patients

An acoustic-perceptual investigation of a phonological phenomenon in which stress is retracted in double-stressed words (e.g., thirTEEN vs THIRteen MEN) was undertaken to identify the locus of functional impairments in speech prosody. Subjects included left-hemisphere-damaged (LHD) and right-hemisphere-damaged (RHD) patients and nonneurological controls. They were instructed to read sentences containing double-stressed target words in the presence of a clause boundary or its absence. Whereas all three groups of subjects were capable of manipulating the acoustic parameters that signal a shift in stress, there were some differences between the performance of the patient groups and that of the normal controls. Further, stress production deficits were more severe in LHD aphasic patients than in RHD patients. LHD speakers exhibited deficits in the control of both temporal and F0 cues. Their F0 disturbance appears to be secondary to a primary deficit in temporal control at the phase or sentence level, as an increased number of continuation rises found for the LHD patients seemed to arise from lengthy pauses within sentences. Findings are highlighted to address the nature of breakdown in speech prosody and the competing views of prosodic lateralization.

Patterns of apraxia associated with the production of intransitive limb gestures following left and right hemisphere stroke

The model of apraxia proposed by Roy (1996) states that three patterns of apraxia should be observed across pantomime and imitation conditions. In the present analysis the frequency and severity of each pattern of apraxia were examined in a consecutive sample of left-(LHD) and right-hemisphere-damaged (RHD) patients during the production of intransitive limb gestures. The results indicated that a significant proportion of LHD and RHD patients were selectively impaired in formulating the ideational component of intransitive limb gestures.

Memory and Encoding of Spoken Discourse Following Right Hemisphere Damage: Evidence from the Auditory Moving Window (AMW) Technique

We investigated the hypotheses that impaired discourse processing following right hemisphere damage is mediated by task difficulty and is associated with deficits in discourse encoding. Spoken discourse passages differing in contextual predictability were presented to right hemisphere-damaged (RHD) patients and to non-brain-damaged (NBD) controls for subsequent recall using the Auditory Moving Window paradigm. To manipulate processing difficulty, speech segments were of normal or accelerated speech rates. The recall results showed that RHD adults recalled less than NBD controls overall and failed to recall major idea units better than minor idea units for high predictability passages presented at accelerated speech rates. Both RHD patients and NBD controls failed to recall major idea units better than minor idea units for low predictability passages, regardless of speech rate. The encoding results showed that RHD adults were both slower overall and differentially slower than NBD controls when listening to accelerated passage segments. Taken together, the encoding and recall results are consistent with the view that extracting passage gist under difficult listening conditions is especially vulnerable for patients with right hemisphere strokes.

Using prosody to resolve temporary syntactic ambiguities in speech production: acoustic data on brain-damaged speakers

Left hemisphere brain lesions resulting in aphasia frequently produce impairments in speech production, including the ability to appropriately transmit linguistic distinctions through sentence prosody. The present investigation gathered preliminary data on how focal brain lesions influence one important aspect of prosody that has been largely ignored in the literature - the production of sentence-level syntactic distinctions that rely on prosodic alterations to disambiguate alternate meanings of a sentence. Utterances characterizing three distinct types of syntactic ambiguities (scope, prepositional phrase attachment, and noun phrase/sentential complement attachment) were elicited from individuals with unilateral left hemisphere damage (LHD), right hemisphere damage (RHD), and adults without brain pathology (NC). A written vignette preceding each ambiguous sentence target biased how the utterance was interpreted and produced. Recorded productions were analysed acoustically to examine parameters of duration (word length, pause) and fundamental frequency (F0) for key constituents specific to each of the ambiguity conditions. Results of the duration analyses demonstrated a preservation of many of the temporal cues to syntactic boundaries in both LHD and RHD patients. The two interpretations of sentences containing 'scope' and 'prepositional phrase attachment' ambiguities were differentiated by all speakers (including LHD and RHD patients) through the production of at least one critical temporal parameter that was consistent across the three groups. Temporal markers of sentences containing 'noun phrase/sentential complement attachment' ambiguities were not found to be encoded consistently within any speaker group and may be less amenable to experimental manipulation in this manner. Results of F0 analyses were far less revealing in characterizing different syntactic assignments of the stimuli, and coupled with other findings in the literature, may carry less weight than temporal parameters in this process. Together, results indicate that the ability to disambiguate sentences using prosodic variables is relatively spared subsequent to both LHD and RHD, although it is noteworthy that LHD patients did exhibit deficits regulating other temporal properties of the utterances, consistent with left hemisphere control of speech timing.

Channel-consistency following unilateral stroke: an examination of patient communications across verbal and nonverbal domains

One way in which the dyadic communicative process can go awry is for one or both parties to send channel-inconsistent communications — communications in which the verbal and nonverbal elements are not matched in emotional valence (e.g., uttering positive words with a frown). We hypothesized that unilateral stroke patients would be likely to send such messages. Given the verbal impairments typically associated with left hemisphere damage (LHD), e.g., agrammatism, and the nonverbal impairments typically associated with right hemisphere damage (RHD), we expected LHD and RHD patients to send messages in which the impaired channel was perceived as inconsistent with the unimpaired channel. Ten LHD, 11 RHD and six normal control patients were videotaped while engaging in social interaction. Observers made judgments about the valence of the patients’ (1) words (based on transcripts of the interactions), and (2) facial expressions (based on soundless videos of the interactions). Analysis of word-face difference scores revealed a significant linear trend, with messages of LHD patients judged more positive in facial expression than in verbal content, messages of RHD patients judged more positive in verbal content than in facial expression, and messages of control patients judged channel-consistent (similar in valence across facial and verbal channels).

Effects of lesion variables and emotion type on the perception of facial emotion.

The purpose of this study was to consider the effects of valence, motoric direction (i.e., approach/withdrawal), and arousal on the perception of facial emotion in patients with unilateral cortical lesions. We also examined the influence of lesion side, site, and size on emotional perception. Subjects were 30 right-hemisphere-damaged (RHD) and 30 left-hemisphere-damaged (LHD) male patients with focal lesions restricted primarily to the frontal, temporal, or parietal lobe. Patient groups were comparable on demographic and clinical neurological variables. Subjects were tested for their ability to match photographs of four facial emotional expressions: happiness, sadness, fear, and anger. Overall, RHD patients were significantly more impaired than LHD patients in perceiving facial emotion. Lesion side, but not site, was associated with motoric direction and valence dimensions. RHD patients had specific deficits relative to LHD patients in processing negative and withdrawal emotions; there were no group differences for positive/approach emotions. Lesion size was not significantly correlated with accuracy of emotional perception.

Fundamental Frequency Encoding of Linguistic and Emotional Prosody by Right Hemisphere-Damaged Speakers

To illuminate the nature of the right hemisphere's involvement in expressive prosodic functions, a story completion task was administered to matched groups of right hemisphere-damaged (RHD) and nonneurological control subjects. Utterances which simultaneously specified three prosodic distinctions (emphatic stress, sentence modality, emotional tone) were elicited from each subject group and then subjected to acoustic analysis to examine various fundamental frequency (F0) attributes of the stimuli. Results indicated that RHD speakers tended to produce F0 patterns that resembled normal productions in overall shape, but with significantly less F0 variation. The RHD patients were also less reliable than normal speakers at transmitting emphasis or emotional contrasts when judged from the listener's perspective. Examination of the results across a wide variety of stimulus types pointed to a deficit in successfully implementing continuous aspects of F0 patterns following right hemisphere insult.

Functional disability and rehabilitation outcome in right hemisphere damaged patients with and without unilateral spatial neglect

Objective: To evaluate the impact of unilateral spatial neglect (USN) on the rehabilitation outcome and long-term functioning in activities of daily living (ADL) and instrumental ADL (IADL) of right hemisphere damaged (RHD) stroke patients. Design: Assessments of sensory-motor and cognitive impairment and of functional disability were conducted upon admission to rehabilitation, upon discharge from the rehabilitation hospital, and 6 months after discharge, up to a year postonset. Setting: The Loewenstein Rehabilitation Hospital, which receives patients from all general hospitals in Israel. Patients: Forty consecutive admissions of adult right-handed patients with a first, single, right hemispheric stroke proven by computed tomography. Based on their total score in the Behavioral Inattention Test for neglect, patients were divided into two groups: 19 with neglect (USN+) and 21 without neglect (USN-). Outcome Measures: Functional Independence Measure, for ADL; The Rabideau Kitchen Evaluation, for IADL. Results: Impairment and disability levels of RHD patients with and without USN were clearly differentiated. Neglect is associated with lower performance on measures of impairment (sensory-motor and cognitive), as well as on measures of disability in ADL and IADL. Differences were significant in all testing periods. The recovery pattern of USN+ patients is slower and more attenuated. In both groups, most improvement occurs in the first 5 months after onset. USN is the major predictor of rehabilitation outcome from admission to follow-up. Conclusions: The significance of neglect as a major source of stroke-related long-term disability justifies further research efforts to develop appropriate therapeutic modalities for this complex, multifactorial syndrome.

Apathy and depressed mood in acquired brain damage: relationship to lesion localization and psychophysiological reactivity.

Apathy is a frequent neurobehavioural sequel in patients with acquired brain damage and it may seriously affect outcome of rehabilitation. Patients with traumatic brain injury, cerebrovascular insults and hypoxic brain injury, categorized into four lesion localization groups: left hemisphere damage (LHD); right hemisphere damage (RHD); bilateral hemispheric damage (BHD); and subcortical damage (SCD) were assessed with the Apathy Evaluation Scale (AES) and Montgomery and Asberg Depression Rating Scale (MADRS). Heart rate and electrodermal activity were recorded in an experimental situation that exposed the patients to mental stressors in order to measure psychophysiological reactivity. Significant differences in level of apathy were found between diagnostic groups as well as between localization subgroups. SCD and RHD patients displayed most apathy. Factor analysis of MADRS revealed a three-factor solution; depressed mood, somatic symptoms and negative symptoms. Apathy was significantly correlated with negative symptoms in all localization subgroups, except among the BHD patients. Apathy was not correlated with depressed mood or somatic symptoms. Moreover, apathy was significantly correlated with heart rate reactivity, but not with electrodermal reactivity. Apathy is common, its severity depending on diagnosis and localization of lesion. Apathy and depression in brain damaged patients share common features, but may be differentiated. The significant relationship between apathy and heart rate may provide a psychophysiological correlation of the disengagement, lack of interest and absence of emotional responsivity typically seen in apathy. The results have implications for the theoretical understanding of apathy and related negative symptoms, and for rehabilitation practice.

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.

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.

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.