Hemispheric processing of affective and linguistic intonation contours in normal subjects

In a previous study of the comprehension of linguistic prosody in brain-damaged subjects, S. R. Grant and W. O. Dingwall (1984. The role of the right hemisphere in processing linguistic prosody, presentation at the Academy of Aphasia, 1984) demonstrated that the right hemisphere (RH) of nonaphasic patients plays a prominent role in the processing of stress and intonation. The present study examines laterality for affective and linguistic prosody using the dichotic listening paradigm. Both types of prosody elicited a significant left ear advantage. This advantage was more pronounced for affective than for linguistic prosody. These findings strongly support previously documented evidence of RH involvement in the processing of affective prosody (R. G. Ley & M. P. Bryden, 1982. A dissociation of right and left hemispheric effects for recognizing emotional tone and verbal content, Brain and Cognition, 1, 3-9). They also provide support for the previously mentioned demonstration of RH involvement in the processing of linguistic intonation (S. Blumstein & W. E. Cooper, 1974. Hemispheric processing of intonation contours, Cortex, 10, 146-158; Grant & Dingwall, 1984).     

Lateralization of visuospatial attention across face regions varies with emotional prosody

It is well-established that linguistic processing is primarily a left-hemisphere activity, while emotional prosody processing is lateralized to the right hemisphere. Does attention, directed at different regions of the talker’s face, reflect this pattern of lateralization? We investigated visuospatial attention across a talker’s face with a dual-task paradigm, using dot detection and language comprehension measures. A static image of a talker was shown while participants listened to speeches spoken in two prosodic formats, emotional or neutral. A single dot was superimposed on the speaker’s face in one of 4 facial regions on half of the trials. Dot detection effects depended on emotion condition—in the neutral condition, discriminability was greater for the right-, than for the left-, side of the face image, and at the mouth, compared to the eye region. The opposite effects occurred in the emotional prosody condition. The results support a model wherein visuospatial attention used during language comprehension is directed by the left hemisphere given neutral emotional prosody, and by the right hemisphere given primarily negative emotional prosodic cues.     

Unattended emotional intonations modulate linguistic prosody processing

Prosody or speech melody subserves linguistic (e.g., question intonation) and emotional functions in speech communication. Findings from lesion studies and imaging experiments suggest that, depending on function or acoustic stimulus structure, prosodic speech components are differentially processed in the right and left hemispheres. This direct current (DC) potential study investigated the linguistic processing of digitally manipulated pitch contours of sentences that carried an emotional or neutral intonation. Discrimination of linguistic prosody was better for neutral stimuli as compared to happily as well as fearfully spoken sentences. Brain activation was increased during the processing of happy sentences as compared to neutral utterances. Neither neutral nor emotional stimuli evoked lateralized processing in the left or right hemisphere, indicating bilateral mechanisms of linguistic processing for pitch direction. Acoustic stimulus analysis suggested that prosodic components related to emotional intonation, such as pitch variability, interfered with linguistic processing of pitch course direction.     

Effects of right and left hemisphere cerebrovascular lesions on discrimination of prosodic and semantic aspects of affect in sentences.

Ten nonaphasic left cerebrovascular accident (CVA) patients, 12 right CVA patients, and 16 normals were matched for age, education, lesion sizes, and postonset intervals; all were right handed. One task consisted of 36 sentences connoting one of six primary emotions (joy, sadness, fear, surprise, disgust, anger) presented binaurally with a neutral emotional tone. Subjects were required to point to the appropriate emotion name on a vertically arranged list. A second task consisted of the same 36 sentences voiced emotionally by humming with a closed mouth, presented binaurally, and requiring the same response as for the preceding task. A third task consisted of 18 of the sentences spoken with concordant emotional tone and the remaining 18 sentences spoken with discordant emotional tone, presented binaurally and requiring pointing to the word "SAME" or "DIFFERENT" arrayed vertically. The right hemisphere (RH) patients were significantly impaired, relative to the left hemisphere (LH) patients and normals, on the pure prosody task (2) and on the emotional concordance task (3), the latter effect being significant only for mismatch categorization. The LH patients performed (nonsignificantly) less well than the RH patients and normals on the verbal contextual task (1). Performances on the three tasks were not significantly correlated in the patient groups. It was concluded that the RH probably dominates for phonetic discrimination of vowel trains (fundamental frequency and/or single vowel or multivowel contour) and that the RH probably dominates for certain forms of selective attention in the verbal domain perhaps involving simultaneous mismatch treatment of ongoing sentence-level, distracting, complementary, verbal processes. Comparison of similar right and left, cortical (frontoparietal), and subcortical (capsule and basal ganglia) lesions suggested, but did not prove, that the RH pure prosody impairment is cortical whereas the RH tonal-semantic mismatch categorization impairment involves subcortical as well as cortical contributions.     

Lesion localization in acquired deficits of emotional expression and comprehension

This study investigated the relationship between intrahemispheric location of lesion and disturbances of emotional expression and comprehension. Twenty-eight right hemisphere strokes, 18 left hemisphere strokes, and 20 controls were examined on a standardized test of the expression, repetition, and comprehension of emotional prosody as well as the visual recognition of emotional situations and faces. The patients were classified into aprosodic syndromes according to the test scores. The lesions were independently traced, and overlapped for each aprosodic syndrome. The results, for lesions in either hemisphere, indicated involvement of the basal ganglia most frequently in aprosodic syndromes followed by anterior temporal lobe and insula lesions. Basal ganglia damage was also seen most frequently in patients with impaired comprehension of emotional facial expressions and situations. The anterior temporal lobe was also frequently involved in patients with such deficits. The basal ganglia emerged as a structure of particular importance in the mediation of emotional expression and comprehension.     

Emotional processing following cortical and subcortical brain damage: contribution of the fronto-striatal circuitry

The present study examined the differential contribution of cortical and subcortical brain structures in emotional processing by comparing patients with focal cortical lesions (n = 32) to those with primarily subcortical dysregulation of the basal ganglia (Parkinson's disease n = 14). A standardized measure of emotional perception (Tübingen Affect Battery) was used. Only patients in the more advanced stages of Parkinson's disease and patients with focal damage to the (right) frontal lobe differed significantly from controls in both facial expression and affective prosody recognition. The findings imply involvement of the fronto-striatal circuitry in emotional processing.     

LATERALIZATION FOR FACIAL EMOTIONAL BEHAVIOR: A METHODOLOGICAL PERSPECTIVE*

Recent attention has focused upon the neuropsychological mechanisms underlying facial emotional expression. The greater intensity of expression and more extensive muscular involvement of the left hemiface have suggested right hemisphere dominance in the expression of emotion. This interpretation is based on the fact that the lower portion of the face is predominantly innervated by the contralateral cerebral hemisphere. The current paper reviews a series of studies on (a) facial asymmetry in normal subjects, (b) facial emotional expression in brain-damaged subjects with unilateral lesions, and (c) peripheral factors mediating facial expression findings. Neuropsychological mechanisms underlying emotional processing are also discussed. Our finding of left-sided facial asymmetries in normals is underscored by our finding that right brain-damaged patients are impaired in the expression of facial emotion. Finally, our studies have demonstrated that the asymmetries in normals and the deficits in patient populations are not artifacts of hemiface size and mobility or facial paralysis and apraxia. Taken together, these studies provide evidence that the right hemisphere is specialized for the expression of facial emotion.     

The nature of hemispheric specialization for prosody perception

Recent evidence suggests a relative right-hemispheric specialization for emotional prosody perception, whereas linguistic prosody perception is under bilateral control. It is still unknown, however, how the hemispheric specialization for prosody perception might arise. Two main hypotheses have been put forward. Cue-dependent hypotheses, on the one hand, propose that hemispheric specialization is driven by specialization for the non-prosody-specific processing of acoustic cues. The functional lateralization hypothesis, on the other hand, proposes that hemispheric specialization is dependent on the communicative function of prosody, with emotional and linguistic prosody processing being lateralized to the right and left hemispheres, respectively. In the present study, the functional lateralization hypothesis of prosody perception was systematically tested by instructing one group of participants to evaluate the emotional prosody, and another group the linguistic prosody dimension of bidimensional prosodic stimuli in a dichotic-listening paradigm, while event-related potentials were recorded. The results showed that the right-ear advantage was associated with decreased latencies for an early negativity in the contralateral hemisphere. No evidence was found for functional lateralization. These findings suggest that functional lateralization effects for prosody perception are small and support the structural model of dichotic listening.     

The sad, the angry, and the asymmetrical brain: dichotic listening studies of negative affect and depression

Dichotic Listening (DL) is a valuable tool to study emotional brain lateralization. Regarding the perception of sadness and anger through affective prosody, the main finding has been a left ear advantage (LEA) for the sad but contradictory data for the anger prosody. Regarding an induced mood in the laboratory, its consequences upon DL were a diminished right ear advantage (REA) for the induction of sadness and an increased REA for the induction of anger. The global results fit with the approach-withdrawal motivational model of emotional processing, pointing to sadness as a right hemisphere emotion but anger processed bilaterally or even in the left hemisphere, depending on the subject's preferred mode of expression. On the other hand, the study of DL in clinically depressed patients found an abnormally larger REA in verbal DL tasks which was predictive of therapeutic pharmacological response. However, the mobilization of the available left hemisphere resources in these responders (reflected in a higher REA) would indicate a remission of the episode but would not assure the absence of new relapses.     

On the lateralization of emotional prosody: an event-related functional MR investigation

In order to investigate the lateralization of emotional speech we recorded the brain responses to three emotional intonations in two conditions, i.e., "normal" speech and "prosodic" speech (i.e., speech with no linguistic meaning, but retaining the 'slow prosodic modulations' of speech). Participants listened to semantically neutral sentences spoken with a positive, neutral, or negative intonation in both conditions and judged how positive, negative, or neutral the intonation was on a five-point scale. Core peri-sylvian language areas, as well as some frontal and subcortical areas were activated bilaterally in the normal speech condition. In contrast, a bilateral fronto-opercular region was active when participants listened to prosodic speech. Positive and negative intonations elicited a bilateral fronto-temporal and subcortical pattern in the normal speech condition, and more frontal activation in the prosodic speech condition. The current results call into question an exclusive right hemisphere lateralization of emotional prosody and expand patient data on the functional role of the basal ganglia during the perception of emotional prosody.     

Cerebral mechanisms for understanding emotional prosody in speech

Hemispheric contributions to the processing of emotional speech prosody were investigated by comparing adults with a focal lesion involving the right (n = 9) or left (n = 11) hemisphere and adults without brain damage (n = 12). Participants listened to semantically anomalous utterances in three conditions (discrimination, identification, and rating) which assessed their recognition of five prosodic emotions under the influence of different task- and response-selection demands. Findings revealed that right- and left-hemispheric lesions were associated with impaired comprehension of prosody, although possibly for distinct reasons: right-hemisphere compromise produced a more pervasive insensitivity to emotive features of prosodic stimuli, whereas left-hemisphere damage yielded greater difficulties interpreting prosodic representations as a code embedded with language content.     

Neurodevelopmental differences in emotional prosody in normal children and children with left and right temporal lobe epilepsy

Emotional prosody, which has been defined as the emotional aspects of speech which communicate pleasure, fear, sorrow, anger, etc., has been demonstrated to be primarily a function of the nondominant hemisphere (typically, the right hemisphere) in adult populations. However, few researchers have addressed the developmental or lateralized nature of emotional prosody in children. In this study, an instrument was developed to measure the receptive aspects of emotional prosody in pediatric populations and administered to normal children ages 6 to 11 years old. An analysis of variance revealed significant age-related differences. Additionally, the instrument was administered to 12 children with right temporal lobe epilepsy and 11 children with left temporal lobe epilepsy. Analysis of variance indicated that there was no significant difference in scores between the left temporal and right temporal lobe groups. However, right temporal epileptic patients scored significantly lower than normal children on all sections of the instrument, suggesting that in children like adults, the right temporal lobe may be dominant with respect to the receptive aspects of emotional prosody.     

Horizontal and vertical attentional orienting in Parkinson’s disease

Patients with Parkinson’s disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N = 10), RPD (N = 9) and controls (N = 10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson’s disease – particularly in LPD – from very subtle slowing to clinically detectable horizontal and/or vertical neglect.     

Affective aprosodia from a medial frontal stroke

BACKGROUND AND OBJECTIVES: Whereas injury to the left hemisphere induces aphasia, injury to the right hemisphere's perisylvian region induces an impairment of emotional speech prosody (affective aprosodia). Left-sided medial frontal lesions are associated with reduced verbal fluency with relatively intact comprehension and repetition (transcortical motor aphasia), but persistent affective prosodic defects associated with right medial frontal lesions have not been described. METHODS: We assessed the prosody of a man who sustained a right medial frontal cerebral infarction seven years prior. RESULTS: While propositional speech expression was normal including syntactic prosody, the patient was impaired at expressing emotions using prosody. His comprehension and repetition of prosody were also impaired but less so than expression. CONCLUSIONS: Right medial frontal lesions can induce an affective aprosodia that primarily impairs expression.     

Horizontal and vertical attentional orienting in Parkinson’s disease

Patients with Parkinson’s disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N = 10), RPD (N = 9) and controls (N = 10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson’s disease – particularly in LPD – from very subtle slowing to clinically detectable horizontal and/or vertical neglect.     

Consequences of brain tumour resection on emotion recognition

Emotion processing impairments are common in patients undergoing brain surgery for fronto-temporal tumour resection, with potential consequences on social interactions. However, evidence is controversial concerning side and site of lesions causing such deficits. This study investigates visual and auditory emotion recognition in brain tumour patients with the aim of clarifying which lesion sites are related to impairments in emotion processing from different modalities. Thirty-four patients were evaluated, before and after surgery, on facial expression and emotional prosody recognition; voxel-based lesion–symptom mapping (VLSM) analyses were performed on patients’ post-surgery MRI images. Results showed that patients’ performance decreased after surgery in both visual and auditory modalities, but, in general, recovered 3 months after surgery. In facial expression recognition, left brain-damaged patients showed greater post-surgery deterioration than right brain-damaged ones, whose performance specifically decreased for sadness and fear. VLSM analysis revealed two segregated areas in the left hemisphere accounting for post-surgery scores for happy (fronto-temporo-insular region) and surprised (middle frontal gyrus and inferior fronto-occipital fasciculus) facial expressions. Our findings demonstrate that surgical removal of tumours in the fronto-temporal region produces impairment in facial emotion recognition with an overall recovery at 3 months, suggesting a partially different representation of positive and negative emotions in the left and right hemispheres for visually – but not auditory – presented emotions; moreover, we show that deficits in specific expression recognition are associated with discrete lesion locations.     

外显和内隐情绪韵律加工的脑机制：近红外成像研究

准确识别言语中的情绪韵律信息对社会交往非常重要。本研究采用功能近红外成像技术, 探索外显和内隐情绪加工条件下愤怒、恐惧、快乐三种情绪韵律加工过程中的大脑皮层神经活动。结果表明, 对愤怒、恐惧、快乐韵律进行特异性加工的脑区分别为左侧额极/眶额叶、右侧缘上回、左侧额下回, 其中右侧缘上回脑区同时受到情绪和任务的调控。此外, 右侧颞中回、颞下回和颞极在情绪外显任务中的激活明显强于内隐任务。本研究的结果部分支持了情绪韵律的层次模型, 也对该模型的第三层次, 即“额区对语音情绪信息的精细加工需要外显性情绪加工任务参与”提出了质疑。     

The role of the cerebral hemispheres in music.

This review examines the cerebral control of musical behaviors. In clinical populations, impairment of related musical and linguistic functions, such as reading, writing, articulation, time sense, and prosody, implies the likely role of the language hemisphere in music. Similarly, for both clinical and normal populations, an investigation of mental abilities common to music and language points to left hemisphere control for certain aspects of temporal order, duration, simultaneity, rhythm, effector motor control, and categorical perception. While clinical studies have revealed deficits in various kinds of music capabilities with both left and right cerebral lesions, normal subjects similarly demonstrate varying degrees of asymmetry for components of music emphasizing pitch, harmony, timbre, intensity, and rhythm. Since differential laterality effects are apparent as a function of subjects' training or adopted strategies, the way musical information is processed may be an important determinant of hemispheric mediation. One hemisphere should not be regarded as “dominant” for music, but rather each interacts with the other, operating according to its own specialization.     

The role of the right hemisphere in the production of linguistic stress

Recent research has proposed a general prosodic disturbance associated with right hemisphere damage (RHD), one encompassing both affective and linguistic functions. The present study attempted to explore whether the ability to produce linguistic prosody was impaired in this patient population. Productions of phonemic stress tokens (e.g., Re'dcoat vs. red coa't) as well as examples of contrastive stress, or sentential emphasis (e.g., Sam hated the movie), were elicited from eight male speakers with unilateral right hemisphere CVAs and seven male control subjects. Two types of analyses were conducted on these utterances. Acoustic analysis focused on the correlates associated with word stress, namely changes in amplitude, duration, and fundamental frequency. The perceptual saliency of emerging cues to stress was also examined by presentation of test tokens to phonetically trained listeners for identification of stress placement. The patients as a group produced fewer acoustic cues to stress compared to the normal subjects, but no statistical differences were found between groups for either stress at the phrase level or at the sentence level. In the perceptual analysis, stress produced by the patient group was judged to be less salient than that for the normal group, although a high degree of variability was evident in both populations. The data suggest a spared processing mechanism for linguistic prosody in RHD speakers, thus mitigating against the view of a general dysprosody tied to RHD.     

Neurology of affective prosody and its functional-anatomic organization in right hemisphere

Unlike the aphasic syndromes, the organization of affective prosody in brain has remained controversial because affective-prosodic deficits may occur after left or right brain damage. However, different patterns of deficits are observed following left and right brain damage that suggest affective prosody is a dominant and lateralized function of the right hemisphere. Using the Aprosodia Battery, which was developed to differentiate left and right hemisphere patterns of affective-prosodic deficits, functional-anatomic evidence is presented in patients with focal ischemic strokes to support the concepts that (1) affective prosody is a dominant and lateralized function of the right hemisphere, (2) the intrahemispheric organization of affective prosody in the right hemisphere, with the partial exception of Repetition, is analogous to the organization of propositional language in the left hemisphere and (3) the aprosodic syndromes are cortically based as part of evolutionary adaptations underlying human language and communication.