Judgement of mood in music following right hemisphere damage.

Evidence on hemispheric specialization has implicated the right hemisphere as having a special role in the mediation of emotion. Since music is an area in which both cognitive and affective aspects of perception can be assessed, the aim of this study was to investigate the effect of right hemisphere damage on perception of emotional meaning or mood in music. An initial pilot study was conducted to select music on which normal subjects were consistent in their judgement of musical mood. The musical stimuli consisted of extracts of classical piano music. The technique used as a measure of musical mood was the Semantic Differential. Tracks of music and adjectival scales were selected for the experimental study in which 15 right hemisphere lesioned patients and normal controls were compared in their response to music. The right hemisphere group demonstrated a characteristic response in their judgement of mood in music. The results are discussed in terms of the role of pitch in judgement of mood in music and in terms of the relationship between music and language.     

Hemiface contributions to hemispheric dominance in visual speech perception

Lateralized displays are used widely to investigate hemispheric asymmetry in language perception. However, few studies have used lateralized displays to investigate hemispheric asymmetry in visual speech perception, and those that have yielded mixed results. This issue was investigated in the current study by presenting visual speech to either the left hemisphere (LH) or the right hemisphere (RH) using the face as recorded (normal), a mirror image of the normal face (reversed), and chimeric displays constructed by duplicating and reversing just one hemiface (left or right) to form symmetrical images (left-duplicated, right-duplicated). The projection of displays to each hemisphere was controlled precisely by an automated eye-tracking technique. Visual speech perception showed the same, clear LH advantage for normal and reversed displays, a greater LH advantage for right-duplicated displays, and no hemispheric difference for left-duplicated displays. Of particular note is that perception of LH displays was affected greatly by the presence of right-hemiface information, whereas perception of RH displays was unaffected by changes in hemiface content. Thus, when investigated under precise viewing conditions, the indications are not only that the dominant processes of visual speech perception are located in the LH but that these processes are uniquely sensitive to right-hemiface information.     

Hemispheric perception of emotional valence from facial expressions.

The authors previously reported that normal subjects are better at discriminating happy from neutral faces when the happy face is located to the viewer's right of the neutral face; conversely, discrimination of sad from neutral faces is better when the sad face is shown to the left, supporting a role for the left hemisphere in processing positive valence and for the right hemisphere in processing negative valence. Here, the authors extend this same task to subjects with unilateral cerebral damage (31 right, 28 left). Subjects with right damage performed worse when discriminating sad faces shown on the left, consistent with the prior findings. However, subjects with either left or right damage actually performed superior to normal controls when discriminating happy faces shown on the left. The authors suggest that perception of negative valence relies preferentially on the right hemisphere, whereas perception of positive valence relies on both left and right hemispheres.     

On hemispheric specialisation and visual field effects in the perception of print: A comment on Jordan, Patching, and Thomas

Introduction Due to structural characteristics of the visual pathways, stimuli that are presented in the right half of the visual field (RVF) are initially projected to the left cerebral hemisphere, while those presented in the left half of the visual field (LVF) are projected to the right cerebral hemisphere. This anatomical feature has frequently been taken to support the notion that the well-documented RVF advantage in recognising printed words is a reflection of functional differences between the two hemispheres; notably that of the dominance of the left hemisphere for processing language. Word stimuli that are sent straight to the left hemisphere are believed to profit from more efficient processing than those sent initially to the right hemisphere, because the latter stimuli must follow a longer and more noisy pathway before reaching the language-dominant hemisphere. In the work by Jordan, Patching, and Thomas (2003) the above notion is further developed to speculate that the point of entry of visual information into the cortex may determine the procedure that will underlie the ensuing word recognition process: "... the left hemisphere can process words by mapping orthographic information in parallel onto lexical entries whereas the right hemisphere has a more rudimentary process, that can only map orthographic information sequentially" (p. 50).     

On hemispheric specialisation and visual field effects in the perception of print: A comment on Jordan,Patching, and Thomas

Introduction Due to structural characteristics of the visual pathways, stimuli that are presented in the right half of the visual field (RVF) are initially projected to the left cerebral hemisphere, while those presented in the left half of the visual field (LVF) are projected to the right cerebral hemisphere. This anatomical feature has frequently been taken to support the notion that the well-documented RVF advantage in recognising printed words is a reflection of functional differences between the two hemispheres; notably that of the dominance of the left hemisphere for processing language. Word stimuli that are sent straight to the left hemisphere are believed to profit from more efficient processing than those sent initially to the right hemisphere, because the latter stimuli must follow a longer and more noisy pathway before reaching the language-dominant hemisphere. In the work by Jordan, Patching, and Thomas (2003) the above notion is further developed to speculate that the point of entry of visual information into the cortex may determine the procedure that will underlie the ensuing word recognition process: "... the left hemisphere can process words by mapping orthographic information in parallel onto lexical entries whereas the right hemisphere has a more rudimentary process, that can only map orthographic information sequentially" (p. 50).     

脑肿瘤患者认知功能障碍的初步研究

目的 :探索脑肿瘤患者认知功能障碍的特点。方法 :采用CLB测验对 31例左侧大脑肿瘤患者、34例右侧大脑肿瘤患者及正常对照组进行测验。结果 :(1)左侧大脑脑肿瘤组四项语言—序贯能力测验成绩明显低于对照组 (P <0 .0 5 ) ,四项空间认知能力成绩无明显差别 (P >0 .0 5 ) ,病例组CLQ为正值 ,表明右半球信息加工能力无明显损害 ;(2 )右侧大脑脑肿瘤组四项空间认知能力测验成绩明显低于对照组 (P <0 .0 5 ) ,四项语言—序贯能力测验成绩中系列数字、偏旁组字、类别组词与对照组间无明显差异 (P >0 .0 5 ) ,系列声音测验成绩有明显差异 (P <0 .0 5 ) ,病例组CLQ为负值 ,表明左半球信息加工能力基本正常。结论 :CLB可以对脑肿瘤患者认知功能障碍进行量化 ,是一种评估左右侧大脑肿瘤患者认知功能障碍的有效方法。     

The Effect of Lateral Visual Fixation and the Direction of Eye Movements on Heartbeat Discrimination

This study was undertaken to determine whether the asymmetrical activation of the two cerebral hemispheres affects the accuracy of heartbeat perception. Hemispheric preference--the tendency to activate one hemisphere rather than the other--was assessed by the directionality of conjugate lateral eye movements. Actual differential hemispheric activation was achieved by contralateral visual fixation. The results of 44 right-handed male subjects showed that right hemisphere preferent subjects ("left-movers") performed better on a heartbeat discrimination task than left hemisphere preferent subjects ("right-movers"). The direction of lateral visual fixation also influenced heartbeat discrimination: subjects fixating to the left were more accurate than those fixating to the right.     

Visual motion perception induced by sounds in vertical plane

The alternation of sounds in the left and right ears induces motion perception of a static visual stimulus (SIVM: Sound-Induced Visual Motion). In this case, binaural cues were of considerable benefit in perceiving locations and movements of the sounds. The present study investigated how a spectral cue – another important cue for sound localization and motion perception – contributed to the SIVM. In experiments, two alternating sound sources aligned in the vertical plane were presented, synchronized with a static visual stimulus. We found that the proportion of the SIVM and the magnitude of the perceived movements of the static visual stimulus increased with an increase of retinal eccentricity (1.875–30°), indicating the influence of the spectral cue on the SIVM. These findings suggest that the SIVM can be generalized to the whole two dimensional audio–visual space, and strongly imply that there are common neural substrates for auditory and visual motion perception in the brain.     

Cerebral Lateralization and Heartbeat Discrimination

This study examined individual differences in visceral perception as a function of cerebral lateral preference as assessed by conjugate lateral eye movements. Subjects were classified as “left movers” (i.e., right hemisphere preferent) or “right movers” (i.e., left hemisphere preferent). “Right movers” performed at chance level on a heartbeat detection task, whereas “left movers” performed significantly above chance. With knowledge-of-results (KOR) training all subjects showed a significant increment in performance, but the left movers maintained their superiority. These results support the hypothesis that performance on a visceral perception task may be subserved by relative activation of the right hemisphere.     

The effect of monocular viewing on heartbeat discrimination

In monocular viewing conditions, an activational imbalance between the cerebral hemispheres was assumed to develop, the direction of which depends on the side of the viewing eye. This assumption was based on the morphological differences between the nasal and the temporal hemiretinas and on physiological data. It was assumed that the hemisphere receiving visual information via the nasal optic fibers, that is, the hemisphere contralateral to the viewing eye, would be the more activated one. Because heartbeat perception is regarded as a predominantly right hemispheric function, it was predicted that during right hemispheric activation created by left monocular viewing heartbeat discrimination performance would be better than during left hemispheric activation created by right monocular viewing. This hypothesis was tested on 30 male right-handed university students who performed a Whitehead-type heartbeat discrimination task while viewing only with the left or with the right eye. Heartbeat perception was more accurate when viewing with the left eye. Additionally, respiratory manipulation during heartbeat discrimination improved performance on this task.     

Electrophysiological correlates of categorical speech perception for voicing contrasts in dogs

Auditory evoked responses (AERs) were recorded from the left and right temporal and parietal scalp regions of ten 15‐week‐old border collies. The AERs were collected while the animals listened to series of consonant‐vowel syllables in which the consonant sounds varied in voice onset time. Analyses of the brain responses indicated that portions of the right‐hemisphere AERs discriminated between the consonant sounds in a categorical manner. These components occurred between 50 and 180 msec following the speech onset. Results were interpreted to indicate that the basic brain mechanisms subserving some aspects of human speech perception are present in non‐primates.     

The left visual-field advantage in rapid visual presentation is amplified rather than reduced by posterior-parietal rTMS

In the present task, series of visual stimuli are rapidly presented left and right, containing two target stimuli, T1 and T2. In previous studies, T2 was better identified in the left than in the right visual field. This advantage of the left visual field might reflect dominance exerted by the right over the left hemisphere. If so, then repetitive transcranial magnetic stimulation (rTMS) to the right parietal cortex might release the left hemisphere from right-hemispheric control, thereby improving T2 identification in the right visual field. Alternatively or additionally, the asymmetry in T2 identification might reflect capacity limitations of the left hemisphere, which might be aggravated by rTMS to the left parietal cortex. Therefore, rTMS pulses were applied during each trial, beginning simultaneously with T1 presentation. rTMS was directed either to P4 or to P3 (right or left parietal cortex) either as effective or as sham stimulation. In two experiments, either one of these two factors, hemisphere and effectiveness of rTMS, was varied within or between participants. Again, T2 was much better identified in the left than in the right visual field. This advantage of the left visual field was indeed modified by rTMS, being further increased by rTMS to the left hemisphere rather than being reduced by rTMS to the right. It may be concluded that superiority of the right hemisphere in this task implies that this hemisphere is less irritable by external interference than the left hemisphere.     

Hemispheric differences in evoked potentials to faces and words

Sixteen right-handed subjects (8 male and 8 female) were asked to compare two faces or two words successively presented at the centre of the visual field. The brain's electrical activity was recorded from the scalp at symmetrical points of the left and right occipital lobes (0(1) and 0(2)) and posterior temporal lobes (T5 and T6). The reference electrode was placed on the scalp vertex (Cz). A multi-factor analysis of variance revealed significant hemispheric differences of the N243 and P406 amplitudes. For the N243 the opposite asymmetry was found for faces and words. For the face matching the N243 amplitude was higher in the right hemisphere, whereas for word matching it was higher in the left hemisphere. For the P406 the asymmetry was in the same direction both for faces and words, with higher amplitude in the left hemisphere. In the case of face matching the hemispheric difference in the P406 was more pronounced, due to a negative shift of the potential in the left hemisphere in the latency range of 200-1,500 ms. Functional asymmetry of the brain in face perception thus appears to be reflected in the brain's electrical activity. We conclude that differentiation in hemispheric functions takes place while encoding information about stimulus in short term memory.     

Bilateral Asymmetry of Skin Conductance Responses During Auditory and Visual Tasks

Bilateral skin conductance (SC) was recorded while dextral subjects engaged in tasks designed to differentially engage the right (RH) and left (LH) hemispheres. Subjects compared strings of speech sounds (LH) and musical chords (RH). They also decided whether written words rhymed (LH) and viewed pictures of faces in a continuous recognition paradigm (RH). SCRs in the right hand were larger during the chords task than the syllables task. The left hand did not differ for the two stimuli. In the visual experiment a comparable effect was obtained in males only. SCRs in the left hand were larger for rhymes than faces; the right hand did not differentiate between stimuli. Sex differences in laterality are considered. Subjects who were more equally balanced in awareness of the two sides of their bodies and subjects with familial sinistrals were more likely to show task appropriate SC changes. Using rote repetition and visual imagery as mnemonics did not affect SC asymmetries.     

Musical training intensity yields opposite effects on grey matter density in cognitive versus sensorimotor networks

Using optimized voxel-based morphometry, we performed grey matter density analyses on 59 age-, sex- and intelligence-matched young adults with three distinct, progressive levels of musical training intensity or expertise. Structural brain adaptations in musicians have been repeatedly demonstrated in areas involved in auditory perception and motor skills. However, musical activities are not confined to auditory perception and motor performance, but are entangled with higher-order cognitive processes. In consequence, neuronal systems involved in such higher-order processing may also be shaped by experience-driven plasticity. We modelled expertise as a three-level regressor to study possible linear relationships of expertise with grey matter density. The key finding of this study resides in a functional dissimilarity between areas exhibiting increase versus decrease of grey matter as a function of musical expertise. Grey matter density increased with expertise in areas known for their involvement in higher-order cognitive processing: right fusiform gyrus (visual pattern recognition), right mid orbital gyrus (tonal sensitivity), left inferior frontal gyrus (syntactic processing, executive function, working memory), left intraparietal sulcus (visuo-motor coordination) and bilateral posterior cerebellar Crus II (executive function, working memory) and in auditory processing: left Heschl’s gyrus. Conversely, grey matter density decreased with expertise in bilateral perirolandic and striatal areas that are related to sensorimotor function, possibly reflecting high automation of motor skills. Moreover, a multiple regression analysis evidenced that grey matter density in the right mid orbital area and the inferior frontal gyrus predicted accuracy in detecting fine-grained incongruities in tonal music.     

The impact of visual movement on auditory cortical responses: a magnetoencephalographic study

We developed a visual 3D model of a space module and analyzed whether activity in the auditory cortex is influenced by rotating the image using magnetoencephalography. We presented 1,000 Hz pure tone as an auditory stimulus in four different visual conditions: (1) RR: a virtual image rotated around the center, (2) VR: images rotated vertically, (3) HR: images rotated horizontally and (4) ST: the images did not rotate. We compared the difference in the auditory evoked component among the conditions. The dipoles were estimated to lie in Heschl’s gyrus. The dipole moment was significantly larger for RR and VR than for ST in the right hemisphere. Investigating the inter-hemispheric differences in each visual condition, the dipole moments for RR and VR were significantly larger in the right hemisphere than the left hemisphere. Auditory activity was influenced by visual movement inducing self-motion perception and the effect of such visual movement on the auditory cortex was right-dominant.     

Dementia as a window to the neurology of art

Art is an expression of neurological function and how it organizes and interprets perception. Recent reports of changes in art performance among patients with frontotemporal dementia have provided an unexpected window to the neurology of art. They confirm that visual art is predominantly in the right hemisphere and suggest a neuroanatomical schema for artistic creativity. The right parietal region is critical for the visuospatial prerequisites of art, and the right temporal lobe integrates and interprets these percepts. The right temporal lobe appears necessary for extracting and exaggerating the essential features of an artistic composition. In contrast, the left parietal region and the left temporal lobe have inhibitory effects on artistic expression through attention to visuospatial detail and semantic labeling, respectively. Frontal-executive functions are also required for artistic expression, particularly right dorsolateral frontal initiation of a network for novelty-seeking behavior. Further study of art in dementia can profitably evaluate this proposed schema for the mechanisms of art in the brain.     

Interhemispheric Difference for Upright and Inverted Face Perception in Humans: An Event-Related Potential Study

We recorded event-related potentials (ERPs) to investigate the interhemispheric difference of the N170 component for upright and inverted face perception in detail in fifteen healthy subjects. This is the first ERP study focusing on interhemispheric differences for face perception by showing faces in the hemifield. The face inversion effect, the prolonged latency and enhanced amplitude were found in both hemispheres. We found that the peak latency of the N170 following both upright and inverted face stimulation showed no significant difference between each hemisphere, though the N170 latency for the inverted face in the left hemisphere was shorter than that in the right hemisphere. The N170 recorded from the hemisphere ipsilateral to the stimulated hemifield showed unique findings. The interhemispheric time difference of the N170 between the right and the left hemispheres when the inverted face was presented in the left hemifield was significantly shorter than in the other three conditions. This unique finding may indicate that the conduction time from the right to the left for inverted face perception is faster than the other conditions, or that the left hemisphere specifically processed the inverted face very rapidly after receiving signals from the right hemisphere. If the N170 was generated by some, at least two, temporally overlapping activities, the different style of a summation of these activities may cause the unique findings found in this study. In conclusion, by presenting face stimuli in the hemifields, we could identify several new findings regarding the N170 component related to the face inversion effect.     

MMPI correlates of relatively localized brain damage

Examined the MMPI correlates of relatively localized brain damage classified along dimensions of laterality and caudality. Forty patients with lateralized lesions that involved anterior or posterior cerebral areas were studied. Based on a multivariate analysis of variance, results revealed significant differences in MMPI profiles between left hemisphere and right hemisphere lesion groups. The MMPI profile for the left hemisphere lesion group is well within the normal range; the right hemisphere lesion group is beyond normal limits, primarily on scales 8 and 2. Several issues are dis cussed in an effort to integrate these findings with previous studies.     

Hemispheric specialization for the visual control of action is independent of handedness

The idea that visually guided action is independent of visual perception has been supported by neurological, neuropsychological, and behavioral studies. In healthy subjects, evidence for this distinction has come from psychophysical studies of the effects of visual illusions on perceptual judgments and object-directed grasping. This evidence is limited, however, by the fact that virtually all studies have involved right-handed subjects using their dominant hand, which is presumably controlled by the left hemisphere. There is tentative evidence from earlier neurological studies that the left hemisphere may in fact play a special role in the integration of visual and motor information during grasping. We designed two experiments to test this idea. The first experiment involved pictorial illusions, which are known to have robust effects on perceptual judgments but little influence on grasping. Right- and left-handed subjects reached out and grasped objects embedded in two different visual illusions with either their dominant or their nondominant hand. For both right- and left-handed subjects, precision grasping with the left hand, but not with the right, was affected by the illusions. In a follow-up experiment, we examined precision grasping in a more natural setting and showed that left-handed subjects use their nondominant (right) hand significantly more as compared with right-handed subjects. We conclude that visuomotor mechanisms encapsulated in the left hemisphere play a crucial role in the visual control of action and that this hemispheric specialization evolved independently of handedness.