Perception of emotions from faces and voices following unilateral brain damage

The importance of the right hemisphere in emotion perception in general has been well documented but its precise role is disputed. We compared the performance of 30 right hemisphere damaged (RHD) patients, 30 left hemisphere damaged (LHD) patients, and 50 healthy controls on both facial and vocal affect perception tasks of specific emotions. Brain damaged subjects had a single episode cerebrovascular accident localised to one hemisphere. The results showed that right hemisphere patients were markedly impaired relative to left hemisphere and healthy controls on test performance: labelling and recognition of facial expressions and recognition of emotions conveyed by prosody. This pertained at the level of individual basic emotions, positive versus negative, and emotional expressions in general. The impairment remained highly significant despite covarying for the group's poorer accuracy on a neutral facial perception test and identification of neutral vocal expressions. The LHD group were only impaired relative to controls on facial emotion tasks when their performance was summed over all the emotion categories and before age and other cognitive factors were taken into account. However, on the prosody test the LHD patients showed significant impairment, performing mid-way between the right hemisphere patients and healthy comparison group. Recognition of positive emotional expressions was better than negative in all subjects, and was not relatively poorer in the LHD patients. Recognition of individual emotions in one modality correlated weakly with recognition in another, in all three groups. These data confirm the primacy of the right hemisphere in processing all emotional expressions across modalities--both positive and negative--but suggest that left hemisphere emotion processing is modality specific. It is possible that the left hemisphere has a particular role in the perception of emotion conveyed through meaningful speech.     

Tactual and auditory vigilance in split-brain man.

Two studies are reported of tactual and auditory vigilance performance in patients with a split-brain or partial commissurotomy to examine the attentional behaviour of the right and left hemisphere, and to identify defects in attention which may be related to the division of the cerebral commissures. The performance of the right hemisphere on all tasks of sustained attention so far studied was substantially better than that of the left. Considerable depletion of concentration was observed for the total split-brain group but not in patients with partial commissurotomy. One of the more unusual phenomena of the split-brain condition is that gaps of attention, often lasting many seconds, occur predominantly on the left hemisphere. The switch to a different type of signal on the same hemisphere does not stop them but the switching of signals from one hemisphere to another does. The defect is interpreted as a failure of attention peculiar to the individual hemisphere under test.     

Receptive prosodic processing in aphasia

The aim of this study was to systematically investigate the capacity of aphasic patients in the comprehension of emotional, conversational, and linguistic prosody in relation to the degree of severity of aphasia. In order to make a contribution to an ongoing discussion about the role of the two cerebral hemispheres in prosodic processing, we compared the results of the left-hemisphere-damaged aphasic group with those of a group of right-hemisphere-damaged patients. We found deficits in both patient groups, but with different profiles across tasks: The processing of emphatic stress was significantly impaired in the aphasic group, but relatively spared in the patients with lesions to the right hemisphere. On the other hand, relatively good performance by the aphasic patients and significantly inferior results from the right hemisphere damaged patients were found in the processing of emotional and conversational prosodic information. The disturbances found in the left hemisphere group were independent of the severity of aphasic impairment.     

Emotional and non-emotional facial behaviour in patients with unilateral brain damage.

Aspects of emotional facial expression (responsivity, appropriateness, intensity) were examined in brain-damaged adults with right or left hemisphere cerebrovascular lesions and in normal controls. Subjects were videotaped during experimental procedures designed to elicit emotional facial expression and non-emotional facial movement (paralysis, mobility, praxis). On tasks of emotional facial expression, patients with right hemisphere pathology were less responsive and less appropriate than patients with left hemisphere pathology or normal controls. These results corroborate other research findings that the right cerebral hemisphere is dominant for the expression of facial emotion. Both brain-damaged groups had substantial facial paralysis and impairment in muscular mobility on the hemiface contralateral to site of lesion, and the left brain-damaged group had bucco-facial apraxia. Performance measures of emotional expression and non-emotional movement were uncorrelated, suggesting a dissociation between these two systems of facial behaviour.     

Right hemisphere dysfunction and emotional processing in ALS: an fMRI study

Emotional processing may be abnormal in amyotrophic lateral sclerosis (ALS). Our aim was to explore functional anatomical correlates in the processing of aversive information in ALS patients. We examined the performance of nine non-demented ALS patients and 10 healthy controls on two functional MRI (fMRI) tasks, consisting of an emotional attribution task and a memory recognition task of unpleasant versus neutral stimuli. During the emotional decision task, subjects were asked to select one of three unpleasant or neutral words. During the memory task, subjects were asked to recognize words presented during the previous task. Controls showed, as expected, greater activation in the right middle frontal gyrus during selection of unpleasant than neutral words, and a greater activation mainly in right-sided cerebral areas during the emotional recognition task. Conversely, patients showed a general increase in activation of the left hemisphere, and reduced activation in right hemisphere in both emotional tasks. Such findings may suggest extra-motor neurodegeneration involving key circuits of emotions, mostly negative, commonly involved in FTD.     

The contribution of anterior and posterior regions of the right hemisphere to the recognition of emotional faces

To investigate the contribution of posterior and anterior parts of the right hemisphere (RH) to emotional facial recognition, we studied 11 participants with anterior strokes of the right hemisphere (ASRH), 16 patients with posterior strokes of the right hemisphere (PSRH), and 31 normal controls. All individuals were right-handed and nondemented. The ability to recognize emotional facial expressions was assessed by using Ekman and Friesen's (1976) Pictures of Facial Affect. Analysis revealed that both groups of patients presented with an impaired recognition of emotional faces. However, patients with PSRH were able to identify facial expressions better than participants with ASRH. In comparison to participants sustaining PSRH, patients with ASRH were particularly impaired on recognizing faces of negative valence. Thus, our results suggest that anterior parts of the RH seem to play an important role in the recognition of emotional facial expressions.     

Differences in recovery from constructional apraxia after right and left hemisphere stroke

Abstract

Previous comparisons of constructional apraxia after right and left hemisphere damage have not investigated the influence of time since onset. This paper reports some preliminary findings from stroke patients in a physical rehabilitation trial. Fifty-five patients with right hemisphere damage and 65 with left hemisphere damage were assessed on the WAIS-R Block Design test at 1 month and 6 months post stroke. The groups were similar at 1 month but the left hemisphere group showed better average recovery by 6 months. There was great variability in amount of recovery within the left hemisphere group, suggesting individual differences in initial reasons for failing Block Design, and corresponding differences in the recovery process. Compensation by the right hemisphere is discussed as one possible process. Future detailed longitudinal studies may be useful in contrasting the cognitive deficits which underlie constructional apraxia after right-sided and left-sided lesions, and would provide evidence on mechanisms of recovery and adaptation.     

Hemispheric specialization in emotion: attention, arousal, and EEG activation in unilateral temporal lobe epilepsy

To investigate the neural processing of emotion in right and left temporal lobe epilepsy (TLE), we monitored EEG during neutral and emotionally positive and negative auditory stimulation. Left TLE patients displayed increased right lateralization and a negative emotional stimulus rating bias, while right TLE patients did not. This EEG arousal and negative affect may reflect deactivated inhibition of the right hemisphere, symptomatically expressed as arousal and anxiety. Failure to increase lateralization to emotional stimuli in right TLE may reflect compromised emotional attention/arousal centers in the right hemisphere. Results support a two-dimensional theory of the neural processing of emotion.     

The restricted effects of right-hemisphere lesions after age one; Wechsler test data

The late effects of early and later lateralized brain lesions were studied with the Wechsler intelligence test in 50 patients with unilateral nonprogressive cerebral lesions incurred in infancy or in childhood. Results differed according to age at lesion for right but not left hemisphere patients; patients with right hemisphere lesions after age one had normal Verbal ratings impaired Performance ratings; patients with earlier right hemisphere lesions were impaired on both ratings.     

Head-down manoeuvre in patients with a high symptom score for orthostatic intolerance reveals impaired right brain frontal lobe vasoreactivity.

OBJECTIVE: Autonomic nerve dysregulation produces a sense of impaired well-being and interferes with work performance in affected individuals. In this study, we characterized the pathophysiology of this condition. METHODS: Six patients with high symptom scores for orthostatic intolerance (OI) along with age- and sex-matched normal volunteers were directed to perform a head-down manoeuvre, and the change in cerebral blood flow (CBF) and cerebral oxygen levels (rSO(2)) in the right and left frontal lobes was measured using near-infrared spectroscopy (NIRS). RESULTS: The head-down manoeuvre induced a much greater increase in right-sided total haemoglobin concentration (THbl) in normal volunteers (0.51+/-0.24) when compared to symptomatic patients (0.0+/-0.04) but had no effect on left-sided THbl (P<0.05) in either group. Five of 6 patients showed a gradual decrease in right-sided THbl when assuming a sitting position, and all patients with this pattern complained of symptoms of multiple autonomic dysfunction. Further, this pattern of changes in right-sided THbl was not observed in normal volunteers. CONCLUSIONS: The gradual decrease of THbl with the sitting position and the lack of increase during the head-down manoeuvre in symptomatic patients suggest that these patients have impaired vasoreactivity in the right frontal lobes. SIGNIFICANCE: This impaired vasoreactivity likely reflects dysfunction of the right hemisphere and the sympathetic nervous system in patients with OI.     

Cognitive functions in patients with MR-defined chronic focal cerebellar lesions

Abstract The aim of the present study was to examine cognitive functions in a group of chronic patients with focal cerebellar lesions. Both effects of localization (anterior vs. posterior lobe) and side (left vs. right cerebellar hemisphere) were of interest. Fourteen patients with infarctions within the territory of the posterior inferior cerebellar artery (PICA) and seven patients with infarctions within the territory of the superior cerebellar artery (SCA) participated. The affected lobules and nuclei were assessed based on 3D MR imaging. The right cerebellar hemisphere was affected in eight PICA and two SCA patients, the left hemisphere in six PICA and four SCA patients. One SCA patient revealed a bilateral lesion. In order to study possible lateralization of functions, subjects performed a language task as well as standard neglect and extinction tests. Moreover, two tests of executive functions were applied. There were no significant group differences apart from a verbal fluency task, in which all cerebellar patients – but especially those with right-sided lesions – were impaired. Voxel-based lesionsymptom mapping (VLSM) revealed that a lesion of the right hemispheric lobule Crus II was associated with impaired performance in the verbal fluency task. In sum, the results showed preserved cognitive abilities in chronic cerebellar patients apart from impairments of verbal fluency in patients with right-cerebellar lesions. The latter findings are in line with the assumption that the right posterolateral cerebellar hemisphere supports functions associated with verbal fluency.     

Asymmetrical Cognitive Deterioration in Demented and Parkinson Patients

Patients with Parkinson's disease and patients with dementia showed greater deterioration on functions attributed to the right cerebral hemisphere, than on functions attributed to the left. Relative to matched controls, Parkinson patients were significantly impaired on right hemisphere tests, but did not differ on left hemisphere tests. Demented patients were significantly deficient on all tests, but right decline was greater than left.Ninety-six patients were tested: 32 diagnosed as senile or presenile dementia, 32 Parkinson patients, and 32 non-neurological patients matched for age, sex and education. Functional performance was assessed by a battery of validated tests for left and right hemisphere cognitive functions. Patients were defined with two scores based on the results of the test: Cognitive Laterality Quotient (CLQ) reflecting the averaged performance on the left hemisphere tests, subtracted from the average performance on right hemisphere tests, and Cognitive Performance Quotient (CPQ), reflecting the total level of performance of both hemispheres. These measures defined a characteristic cognitive profile for each group.     

Visuospatial performance in left-handed patients with unilateral brain lesions

A test of visuospatial judgment was given to left-handed patients with lesions of either the right or left hemisphere. In right-handed patients impaired performance on the test has been found to be almost exclusively associated with right hemisphere disease, the performance of patients with left hemisphere disease being comparable to that of controls. The left-handed patients in this study showed the same performance pattern: a high proportion of patients with right hemisphere lesions performed defectively while all the patients with left hemisphere lesions performed on a normal level. Thus the findings are in accord with the conclusion that hemispheric cerebral organisation with respect to the mediation of visuospatial performance do not differ in right-handers and left-handers.     

Hemisphere preference, phobia, and depression

The present study was undertaken in order to examine whether depression and anxiety are related to preference for a right hemisphere mode of thinking. On the basis of a paper-and-pencil test presumably measuring hemisphere preference (Preference Test; Zenhausern, 1978), normal subjects (N = 75) were assigned to a group characterized by a left hemisphere thinking style, a group characterized by a right hemisphere thinking style and a group with mixed tendencies (left and right hemisphere tendencies). Additionally, subjects completed the Fear Questionnaire and the Depression Symptom Inventory. It was found that subjects with a right hemisphere thinking style reported more depressive and fear symptoms than subjects with a left hemisphere thinking style. This finding is in line with theories which assume that the right hemisphere is characterized by a negative, dysphoric emotional tendency.     

Grey scales uncover similar attentional effects in homonymous hemianopia and visual hemi-neglect

Multi-component models of visual hemi-neglect have postulated that visual hemi-neglect is characterised by various attentional deficits. A grey scales task has been developed to quantify the early, automatic, (perhaps obligatory) ipsilesional orienting of visual attention, frequently assumed as the first of these attentional deficits. Explanations for this attentional imbalance are up until now mainly formulated in terms of right hemisphere activation. This lateral attentional bias has also been demonstrated in controls, in whom it is expressed as a leftward perceptual asymmetry. We reproduced previous literature findings on a grey scales task, considering controls and neglect patients. Three patients with neglect showed an extreme ipsilesional lateral bias. This bias did not change during or after cognitive rehabilitation. Additionally, we presented this grey scale task to 32 patients with left- and right-sided homonymous hemianopia (HP). HP is the loss of sight in one visual hemi-field. The HH patients had no clinical signs of impaired lateralised attention. Results revealed that HH patients showed a similar ipsilesional bias, albeit to a lesser degree than in neglect. Left-sided HH patients presented a quantitatively similar, but qualitatively opposite bias than the right-sided HH patients. We suggest that sensory effects can be an alternative source of attentional imbalance, which can interact with the previously proposed (right) hemispheric effects. This suggests that the perceptual asymmetry in the grey scales task is not necessarily an indicator of impaired right hemisphere attention. It rather suggests a pattern of functional cerebral asymmetry, which can also be caused by asymmetric sensory input.     

Defective comprehension of emotional faces and prosody as a result of right hemisphere stroke: modality versus emotion-type specificity.

Studies of patients with brain damage, as well as studies with normal subjects have revealed that the right hemisphere is important for recognizing emotions expressed by faces and prosody. It is unclear, however, if the knowledge needed to perform recognition of emotional stimuli is organized by modality or by the type of emotion. Thus, the purpose of this study is to assess these alternative a priori hypotheses. The participants of this study were 30 stroke patients with right hemisphere damage (RHD) and 31 normal controls (NC). Subjects were assessed with the Polish adaptation of the Right Hemisphere Language Battery of Bryan and the Facial Affect Recognition Test based on work of Ekman and Friesen. RHD participants were significantly impaired on both emotional tasks. Whereas on the visual-faces task the RHD subjects recognized happiness better than anger or sadness, the reverse dissociation was found in the auditory-prosody test. These results confirm prior studies demonstrating the role of the right hemisphere in understanding facial and prosodic emotional expressions. These results also suggest that the representations needed to recognize these emotional stimuli are organized by modality (prosodic-echoic and facial-eidetic) and that some modality specific features are more impaired than others.     

Comprehension of affective and nonaffective prosody

We studied patients with damage of either the right (RHD) or left hemisphere (LHD) and control subjects to determine whether the RHD patients had a global or limited prosodic defect. Compared with LHD patients and controls, RHD subjects had decreased comprehension of emotional prosody. Both LHD and RHD groups had more impaired comprehension of propositional prosody than controls, but the RHD and LHD groups did not differ. The right hemisphere, therefore, seems to be dominant for comprehending emotional prosody but not propositional prosody.     

Visual half-field testing for defining cerebral hemisphere speech laterality

The purpose of this study was to investigate to what extent the noninvasive visual half-field (VHF) test can reliably determine cerebral speech dominance for the individual patient with partial epilepsy considered for surgical treatment. The present VHF test consisted of a list of 36 words presented correctly and mirrored in the lateral visual fields to 13 right-handed and 14 left-handed control subjects and to 14 right-handed and 2 left-handed patients with partial epilepsy. In the controls, it was found that all right-handed and 10 out of 14 left-handed control subjects showed a right VHF (i.e., left hemisphere) advantage. Three of the left-handed control subjects showed the opposite pattern, and one showed no visual field advantage. All of the right-handed patients showed a right VHF advantage, except one who showed no VHF advantage. The two left-handed patients had both a left VHF advantage. Intracarotid amytal speech testing documented left hemisphere speech dominance in all right-handed patients. Of the two left-handed patients, one had right-sided, the other bilateral speech representation. The results suggest that the present VHF test reliably predicts cerebral hemisphere speech in patients with epilepsy.     

Cognitive asymmetry in dyslexic families

On a Cognitive Laterality Battery designed to measure functioning of the left and right cerebral hemisphere, dyslexic children were consistently better on tests of right hemisphere function than on tests of left. Surprisingly, most (90%) of the first degree family members of dyslexics also had the same, right dominant profile, even though most of them claimed never to have a reading problem.

In a series of reading tests where letters were flashed one at a time, the dyslexics were selectively impaired on the test requiring sequential analysis. Since their reading scores were correlated with overall left and right hemisphere performance and with each hemisphere separately, it was hypothesized that dyslexics were “locked” into a right hemisphere mode of processing which governed all their cognitive activity.     

Auditory vocabulary of the right hemisphere following brain bisection or hemidecortication.

Unilateral scores of two commissurotomy and three (one left and two right) hemispherectomy patients were obtained on standardized auditory language comprehension tests which use pointing responses to a pictorial array. Unilateral performance by the commissurotomy patients was achieved by restricting the pictorial array to one visual half field, using a novel contact lens system which permits ocular scanning of the lateralized stimulus and self-monitoring of task performance. Using the Peabody and Ammons Picture Vocabulary Tests, the auditory vocabulary in the disconnected or isolated right hemispheres was found to be equivalent to that of normal subjects of ages 8:1 to 16:3 with a mean of 11:7 (eleven years and 7 months old). At the same time, standardized aphasia tests showed that the picture vocabulary in the right hemispheres is similar to that of a heterogeneous population of aphasics, even though the right hemispheres did not behave quite like any classical aphasic diagnostic group. No significant differences were found between right hemisphere comprehension of object vs. action names. Results indicated that vocabulary as a function of word frequency followed the same pattern in the right and left hemisphere although the right hemisphere was consistently lower. This parallel between the two hemispheres was conjectured to reflect some similar or even shared lexical structures in the two hemispheres. Together with other data on the performance of the right hemisphere on the Token Test (Zaidel, 1976), the results suggest a complex model of the development of language laterality in the brain, in which some, but not all, auditory language functions continue to develop in the right hemisphere past what is generally regarded as the critical period for language acquistion. In general, auditory language comprehension is better characterized as that of an "average aphasic" than that of a child of a specific age.