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Cerebral lateralisation is a core organising principle of the brain that is characterised by a complex pattern of hemispheric specialisations and interhemispheric interactions. In various mental disorders, functional and/or structural hemispheric asymmetries are changed compared to healthy controls, and these alterations may contribute to the primary symptoms and cognitive impairments of a specific disorder. Since multiple genetic and epigenetic factors influence both the pathogenesis of mental illness and the development of brain asymmetries, it is likely that the neural developmental pathways overlap or are even causally intertwined, although the timing, magnitude, and direction of interactions may vary depending on the specific disorder. However, the underlying developmental steps and neuronal mechanisms are still unclear. In this review article, we briefly summarise what we know about structural, functional, and developmental relationships and outline hypothetical connections, which could be investigated in appropriate animal models. Altered cerebral asymmetries may causally contribute to the development of the structural and/or functional features of a disorder, as neural mechanisms that trigger neuropathogenesis are embedded in the asymmetrical organisation of the developing brain. Therefore, the occurrence and severity of impairments in neural processing and cognition probably cannot be understood independently of the development of the lateralised organisation of intra- and interhemispheric neuronal networks. Conversely, impaired cellular processes can also hinder favourable asymmetry development and lead to cognitive deficits in particular. [ABSTRACT FROM AUTHOR]

Tinnitus spatial localisation is an essential attribute of tinnitus perception and how it is separated from other ongoing neural activity. A scoping review was undertaken to determine how tinnitus localisation is reported, the role of the perceived spatial location of tinnitus on neurophysiology and if sound presented spatially can change tinnitus perception. Following reading of the full-text articles and including articles from reference lists, 46 articles were included for review. Six themes emerged from the results. 1. Where tinnitus was localised. 2. The effects of tinnitus on localisation. 3. The mechanisms underpinning tinnitus spatial location. 4. Masking. 5. Auditory training. 6. Multisensory training and virtual reality (VR). Tinnitus is much more complex than the often-used description of 'ringing in the ears'. Tinnitus can be heard anywhere in and around the head. Spatial sound presentation and perceptual training approaches may disrupt spatial selective attention to tinnitus and appear as changes in some of the neural networks involved in sound localisation. Where tinnitus is heard is a critical aspect of its perception, but its report, even in studies purporting to study localisation, is too general. A matrix for standardised minimum reporting of tinnitus location is recommended. [ABSTRACT FROM AUTHOR]

Slow feeding devices (SFDs) are useful tools in order to improve the horse well‐being and to reduce wastage, but their use may result in unnatural posture during feeding and frustration behaviours. Moreover, it may be important to evaluate the laterality during feeding. The aim of the study was to investigate ponies' feeding behaviour (i.e., lateralisation, frustration, postural eating style) with different hay feeding methods: on the ground (G), a fully filled hay net (HF), a partially filled hay net (HL), and a slow feeder hay box (HB). Nine ponies of two different breed types (Shetland and Welsh/Cob) were evaluated. Video recordings were obtained and then behavioural analysis was conducted. Data were analysed statistically using k‐means cluster analysis, repeated measurement mixed model procedure, principal component analysis (PCA) and Pearson's correlation coefficient. Head tilting was more often performed during feeding from HF and HL compared to G and HB. Forelimb forward, referring to the position that ponies assumed during feeding, was performed less frequently with the hay nets. Ponies, in particular Welsh/Cobs, tended to be more left‐lateralized and performed more backward ears when feeding from the hay nets. Blink rate was observed to be greater when ponies were fed from G. No head pushing, striking with forelimb and pawing while feeding was seen. Animals fed from HF tended to eat from the top of the hay net and consequently showed an arched neck; while HL and HB showed for elongated neck an intermediate pattern between G and HF. From our results, HB seemed to be a useful compromise between natural feeding on the ground and the use of hay nets. [ABSTRACT FROM AUTHOR]

Purpose: The anterior stability of reverse total shoulder arthroplasty is affected by multiple factors. However, the effect of glenosphere inclination on stability has rarely been investigated, which is what this study aims to look into. Methods: Reverse shoulder arthroplasty was performed on 15 cadaveric human shoulders. The anterior dislocation forces and range of motion in internal rotation in the glenohumeral joint (primary measured parameters) were tested in a shoulder simulator in different arm positions and implant configurations, as well as with a custom-made 10° inferiorly inclined glenosphere. The inclination and retroversion of the baseplate as well as the distance between the glenoid and coracoid tip in two planes (secondary measured parameters) were evaluated on CT scans. Results: In biomechanical testing, the custom-made inclined glenosphere showed no significant influence on anterior stability other than glenoid lateralisation over all arm positions as well as the neck-shaft angle in two arm positions. The 6 mm lateralised glenosphere reduced internal rotation at 30° and 60° of glenohumeral abduction. In 30° of glenohumeral abduction, joint stability was increased using the 155° epiphysis compared with the 145° epiphysis. The mean inclination was 16.1°. The inclination was positively, and the distance between the glenoid and coracoid tip in the anterior-to-posterior direction was negatively correlated with anterior dislocation forces. Conclusions: The custom-made inferiorly inclined glenosphere did not influence anterior stability, but baseplate inclination itself had a significant effect on stability. [ABSTRACT FROM AUTHOR]

Simple Summary: Animals and plants present asymmetric structures in nature. The most relevant motor behavioural manifestation of lateralisation is handedness, which is defined as the consistent use of one effector rather than the other in performing certain tasks. In animals, including human beings, handedness is associated with the presence of a nervous system. Researchers have recently challenged this idea by reporting that even organisms without a nervous system, such as plants, exhibit similarities with animals in terms of directional movement patterns (i.e., right-handed prevalence), opening up the possibility of a comparative study of handedness across taxa. Here, we advance a comparative approach to the study of handedness in plants by adopting the experimental paradigms already used to research laterality in various animal species. Structural and functional asymmetries are traceable in every form of life, and some lateralities are homologous. Functionally speaking, the division of labour between the two halves of the brain is a basic characteristic of the nervous system that arose even before the appearance of vertebrates. The most well-known expression of this specialisation in humans is hand dominance, also known as handedness. Even if hand/limb/paw dominance is far more commonly associated with the presence of a nervous system, it is also observed in its own form in aneural organisms, such as plants. To date, little is known regarding the possible functional significance of this dominance in plants, and many questions remain open (among them, whether it reflects a generalised behavioural asymmetry). Here, we propose a comparative approach to the study of handedness, including plants, by taking advantage of the experimental models and paradigms already used to study laterality in humans and various animal species. By taking this approach, we aim to enrich our knowledge of the concept of handedness across natural kingdoms. [ABSTRACT FROM AUTHOR]

Introduction: The use of Magnetic Resonance Imaging (MRI) T2 relaxometry and spectroscopy has added new dimensions to the imaging of Temporal Lobe Epilepsy (TLE). Advanced techniques like MRI diffusion and MRI perfusion are new additions to the MRI protocol for epilepsy. Aim: To study the diagnostic value of T2 relaxation time in Electroencephalogram (EEG) confirmed seizure cases. Materials and Methods: A single-centre, cross-sectional study was conducted at Department of Radiodiagnosis, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India, from December 2020 to November 2022 at a tertiary care hospital. All patients were subjected to MRI with a special epilepsy protocol and T2 relaxometry. Hippocampal T2 relaxation values for each slice were measured by placing a Region of Interest (ROI) on the representative image obtained from the T2 relaxometry sequence, focusing on the hippocampus in both the control and study groups. The control group (n=30) consisted of healthy volunteers, whereas the case group (n=36) comprised patients presenting with a history of seizures with positive MRI and EEG findings. Mean T2 relaxation time was calculated in each ROI, and an average was derived. Mean and Standard Deviation (SD) were calculated for the continuous variables, while ratios and proportions were calculated for the categorical variables. To determine the association of T2 relaxometry values in the study and control groups, an unpaired t-test was used. Results: The mean age of participants was 25.14±9.35 years (ranging from 9 to 51 years). The male-to-female ratio was 1.25:1. Hippocampal atrophy (32 out of 36 cases) and T2 signal alteration (30 out of 36 cases) were the most commonly identified features in Mesial Temporal Sclerosis (MTS). MRI without T2 relaxometry had a sensitivity of 94%. In two cases, where only mild hippocampal atrophy was identified in the conventional MRI sequence, making the diagnosis dubious, T2 relaxometry revealed increased T2 relaxation time in the head of the hippocampus and guided a proper diagnosis. EEG was able to lateralise seizures in 8 out of 13 right MTS cases (61.5%), 10 out of 17 left MTS cases (58.9%), and 5 out of 6 cases of bilateral MTS (83%). Conclusion: T2 relaxometry allows quantification of hippocampal signal intensity, allowing the detection of even subtle changes in signal intensity that are difficult to perceive by visual assessment.

Lateralisation is a well-established phenomenon observed in an increasing number of insect species. This study aims to obtain basic details on lateralisation in courtship and mating behaviour in Ostrinia furnacalis , the Asian corn borer. We conducted laboratory investigations to observe lateralisation in courtship and mating behaviours in adult O. furnacalis. Our goal was also to detect lateralised mating behaviour variations during sexual interactions and to elucidate how these variances might influence the mating success of males. Our findings reveal two distinct lateralised traits: male approaches from the right or left side of the female and the direction of male turning displays. Specifically, males approaching females from their right side predominantly exhibited left-biased 180° turning displays, while males approaching females from the left-side primarily displayed right-biased 180° turning displays. Notably, left-biased males, executing a 180° turn for end-to-end genital contact, initiated copulation with fewer attempts and began copulation earlier than their right-biased approaches with left-biased 180° turning displays. Furthermore, mating success was higher when males subsequently approached the right side of females during sexual encounters. Left-biased 180° turning males exhibited a higher number of successful mating interactions. These observations provide the first report on lateralisation in the reproductive behaviour of O. furnacalis under controlled laboratory conditions and hold promise for establishing reliable benchmarks for assessing and monitoring the quality of mass-produced individuals in pest control efforts. [ABSTRACT FROM AUTHOR]

Introduction: The use of Magnetic Resonance Imaging (MRI) T2 relaxometry and spectroscopy has added new dimensions to the imaging of Temporal Lobe Epilepsy (TLE). Advanced techniques like MRI diffusion and MRI perfusion are new additions to the MRI protocol for epilepsy. Aim: To study the diagnostic value of T2 relaxation time in Electroencephalogram (EEG) confirmed seizure cases. Materials and Methods: A single-centre, cross-sectional study was conducted at Department of Radiodiagnosis, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India, from December 2020 to November 2022 at a tertiary care hospital. All patients were subjected to MRI with a special epilepsy protocol and T2 relaxometry. Hippocampal T2 relaxation values for each slice were measured by placing a Region of Interest (ROI) on the representative image obtained from the T2 relaxometry sequence, focusing on the hippocampus in both the control and study groups. The control group (n=30) consisted of healthy volunteers, whereas the case group (n=36) comprised patients presenting with a history of seizures with positive MRI and EEG findings. Mean T2 relaxation time was calculated in each ROI, and an average was derived. Mean and Standard Deviation (SD) were calculated for the continuous variables, while ratios and proportions were calculated for the categorical variables. To determine the association of T2 relaxometry values in the study and control groups, an unpaired t-test was used. Results: The mean age of participants was 25.14±9.35 years (ranging from 9 to 51 years). The male-to-female ratio was 1.25:1. Hippocampal atrophy (32 out of 36 cases) and T2 signal alteration (30 out of 36 cases) were the most commonly identified features in Mesial Temporal Sclerosis (MTS). MRI without T2 relaxometry had a sensitivity of 94%. In two cases, where only mild hippocampal atrophy was identified in the conventional MRI sequence, making the diagnosis dubious, T2 relaxometry revealed increased T2 relaxation time in the head of the hippocampus and guided a proper diagnosis. EEG was able to lateralise seizures in 8 out of 13 right MTS cases (61.5%), 10 out of 17 left MTS cases (58.9%), and 5 out of 6 cases of bilateral MTS (83%). Conclusion: T2 relaxometry allows quantification of hippocampal signal intensity, allowing the detection of even subtle changes in signal intensity that are difficult to perceive by visual assessment. [ABSTRACT FROM AUTHOR]

The frequency of left-handedness in humans is ~10% worldwide and slightly higher in males than females. Twin and family studies estimate the heritability of human handedness at around 25%. The low but substantial frequency of left-handedness has been suggested to imply negative frequency-dependent selection, e.g. owing to a ‘surprise’ advantage of left-handers in combat against opponents more used to fighting right-handers. Because such game-theoretic hypotheses involve social interaction, here we perform an analysis of the evolution of handedness based on kin-selection, which is understood to play a major role in the evolution of social behaviour generally. We show that: (1) relatedness modulates the balance of right-handedness vs. left-handedness, according to whether left-handedness is marginally selfish vs. marginally altruistic; (2) sex differences in relatedness to social partners may drive sex differences in handedness; (3) differential relatedness of parents and offspring may generate parent–offspring conflict and sexual conflict leading to the evolution of maternal and paternal genetic effects in relation to handedness; and (4) differential relatedness of maternal-origin vs. paternal-origin genes may generate intragenomic conflict leading to the evolution of parent-of-origin-specific gene effects – such as ‘genomic imprinting’ – and associated maladaptation.

Simple Summary: As concerns over animal welfare grow, individuals working in animal husbandry need easier ways to assess the psychological wellbeing of livestock. Recent research in lateralisation and stress has helped scientists find links between stress and the sides of the body animals use to inspect new objects and people or engage in new experiences. Research has shown that the left side of the brain processes familiar conditions, while the right side of the brain is more often used for new situations. These sides of the brain correspond to behaviours expressed with the opposite side of the body. Animals often use a specific eye or leg when initiating behavioural responses or interactions which can be assumed to link to the opposite side of the brain. This article summarised the existing literature for lateralisation in common livestock species in addition to advocating for increased use of thermography when assessing welfare in livestock. Lateralised behavioural responses to environmental stressors have become more frequently used as indicators of social welfare in animals. These lateralised behavioural responses are under the control of asymmetrical brain functions as part of the primary functions of most vertebrates and assist in primary social and survival functions. Lateralised behavioural responses originating from the left hemisphere are responsible for processing familiar conditions, while the right hemisphere is responsible for responding to novel stimuli in the environment. The forced lateralisation and side preference tests have been used to determine the visual lateralised behavioural responses in livestock to environmental stressors. Limb preference during movement has also been used to determine motor lateralisation. Although behavioural investigations in livestock have recorded lateralised behavioural responses to environmental stressors, there are still limitations in the implication of lateralisation to other conditions, such as restraint and invasive procedures. Thus, it is important to have a non-invasive measure for these lateralised behavioural responses. Recently, lateralised behavioural responses have been correlated with the use of infrared temperature of external body surfaces, such as the eyes and coronary bands of limbs. This review summarised the different forms of the lateralised behavioural responses in livestock, especially cattle and horses, to environmental stressors, and the association between these responses and the relevant external body surfaces' infrared temperature, with the purpose of improving the use of non-invasive measures in assessing welfare conditions in animals. The combination of the lateralised behavioural responses and infrared temperature of external body surfaces to environmental stressors could improve the assessment strategies of welfare conditions and the related additional husbandry interventions that could be applied to improve the welfare of farm animals. [ABSTRACT FROM AUTHOR]

Reverse total shoulder arthroplasty (RTSA) implants allow variation in lateral and distal offset (LO and DO). The aim of this study was to measure, compare, and classify LO and DO and to assess the effects of modular changes using 2 humeral RTSA implants (one Grammont and one onlay-type) paired with a common modular glenoid component. Three thousand eight hundred sixty virtual RTSA models were created. Measurements of LO and DO between reference points (B—center of the 'baseplate;' C—'glenosphere' center of rotation; P—pivot point of the 'insert;' M—midpoint of the distal surface of the 'tray' in the onlay humeral implant or midpoint of the proximal surface of the 'spacer' in the Grammont implant; J—junction of humeral stem and 'tray,' 'liner' or 'spacer;' H—distal end of stem) were taken. 'Glenoid offset' was distance BP (comprising BC and CP); 'humeral offset' was distance PH (comprising PJ, JM, and MH); their sum was the 'global offset.' Global LO and DO measurements were 14.9-30.9 mm and 13.1-36.3 mm, for the Grammont implant, and 23.0-52.6 mm and 18.0-42.2 mm for the onlay implant. Glenoid LO and DO measurements were 8.2-17.3 mm and 16.3-25.0 mm for the Grammont implant and 11.6-23.1 mm and 12.8-23.3 mm for the onlay implant. LO and DO did not vary proportionally in either implant type. Baseplate modularity affects distance BC; 'glenosphere' modularity affects distance BC, ('glenosphere' eccentricity and lateralization) and/or distance CP ('glenosphere' diameter). Humeral modularity affects distance PH (stem, 'insert,' 'tray,' and 'spacer' geometry, overall neck shaft angle [NSA]) and distance CP (overall NSA). Overall NSA also dictated the relative amount of humeral LO and DO resulting from other humeral modular changes. Both Grammont and onlay humeral RTSA implants paired with a common modular glenoid component can be configured to create a large range of LO and DO, but values are typically greater when using the onlay humeral component. This is despite the higher NSA of the Grammont implant which would be expected to result in more DO. The described classification of DO together with LO may be beneficial. Previous classifications of RTSA based on their 'glenoid' (distance BP) and 'humeral' (distance PH) offsets are misleading. Distance BC should be considered as the measure of 'glenoid' and distance CH as the measure of 'humeral' offset. The 'glenosphere' is best thought of as a 'nonglenoid, nonhumeral spacer' that can affect both BC and CH. [ABSTRACT FROM AUTHOR]

Introduction: Auditory verbal hallucinations (AVHs), or hearing non-existent voices, are a common symptom in psychosis. Recent research suggests that AVHs are also experienced by neurotypical individuals. Individuals with schizophrenia experiencing AVHs and neurotypicals who are highly prone to hallucinate both produce false positive responses in auditory signal detection. These findings suggest that voice-hearing may lie on a continuum with similar mechanisms underlying AVHs in both populations. Methods: The current study used a monaural auditory stimulus in a signal detection task to test to what extent experimentally induced verbal hallucinations are (1) leftlateralised (i.e., more likely to occur when presented to the right ear compared to the left ear due to the left-hemisphere dominance for language processing), and (2) predicted by self-reported hallucination proneness and auditory imagery tendencies. In a conditioning task, fifty neurotypical participants associated a negative word on-screen with the same word being played via headphones through successive simultaneous audio-visual presentations. A signal detection task followed where participants were presented with a target word on-screen and indicated whether they heard the word being played concurrently amongst white noise. Results: Results showed that Pavlovian audio-visual conditioning reliably elicited a significant number of false positives (FPs). However, FP rates, perceptual sensitivities, and response biases did not differ between either ear. They were neither predicted by hallucination proneness nor auditory imagery. Discussion: The results show that experimentally induced FPs in neurotypicals are not left-lateralised, adding further weight to the argument that lateralisation may not be a defining feature of hallucinations in clinical or non-clinical populations. The findings also support the idea that AVHs may be a continuous phenomenon that varies in severity and frequency across the population. Studying induced AVHs in neurotypicals may help identify the underlying cognitive and neural mechanisms contributing to AVHs in individuals with psychotic disorders. [ABSTRACT FROM AUTHOR]

IntroductionAuditory verbal hallucinations (AVHs), or hearing non-existent voices, are a common symptom in psychosis. Recent research suggests that AVHs are also experienced by neurotypical individuals. Individuals with schizophrenia experiencing AVHs and neurotypicals who are highly prone to hallucinate both produce false positive responses in auditory signal detection. These findings suggest that voice-hearing may lie on a continuum with similar mechanisms underlying AVHs in both populations.MethodsThe current study used a monaural auditory stimulus in a signal detection task to test to what extent experimentally induced verbal hallucinations are (1) left-lateralised (i.e., more likely to occur when presented to the right ear compared to the left ear due to the left-hemisphere dominance for language processing), and (2) predicted by self-reported hallucination proneness and auditory imagery tendencies. In a conditioning task, fifty neurotypical participants associated a negative word on-screen with the same word being played via headphones through successive simultaneous audio-visual presentations. A signal detection task followed where participants were presented with a target word on-screen and indicated whether they heard the word being played concurrently amongst white noise.ResultsResults showed that Pavlovian audio-visual conditioning reliably elicited a significant number of false positives (FPs). However, FP rates, perceptual sensitivities, and response biases did not differ between either ear. They were neither predicted by hallucination proneness nor auditory imagery.DiscussionThe results show that experimentally induced FPs in neurotypicals are not left-lateralised, adding further weight to the argument that lateralisation may not be a defining feature of hallucinations in clinical or non-clinical populations. The findings also support the idea that AVHs may be a continuous phenomenon that varies in severity and frequency across the population. Studying induced AVHs in neurotypicals may help identify the underlying cognitive and neural mechanisms contributing to AVHs in individuals with psychotic disorders.

Introduction: Hand-eye coordination is essential to carry out daily activities or take part in sports. Developing strong visual-motor coordination is especially important for athletes or musicians who rely on it for their careers. Goal: This study aimed to evaluate visual-motor coordination in drummers’ upper limbs. Materials and methods: The study group consisted of 60 men, aged 20 to 30 years (average 24.62 ±2.48). The respondents were divided into two groups, group P consisted of 30 experienced drummers and group N of 30 non-drummers. Standardized tests were employed: Relative Hand Skill test (RHS test) and a plate tapping test. Results: The RHS test conducted on an original sample demonstrated no significant difference between the P and N group for the dominant limb (p=0.7272) or the non-dominant limb (p=0.3274). A significant difference was observed between the P and N group in the plate tapping test. The difference in the plate tapping test results between the dominant and non-dominant hands was significantly smaller in the P group than in the N group (p< 0.0001).

The behavioural outcomes associated with atypical cerebral lateralization during the early stages of cognitive development is an interesting research venture. However, there are few tasks for assessing lateralization in young children. The current study describes the Magic Hat task and the Teddy Bear Picnic task, which were designed to measure the lateralization of language and visuospatial attention, respectively, in children as young as three years old. Forty-five adults were recruited to complete the child-friendly tasks as well as the Word Generation and Landmark tasks whilst functional Transcranial Doppler ultrasound (fTCD) measured cerebral blood flow velocity. As expected, at the group level, the Magic Hat task produced left hemisphere lateralization, and the Teddy Bear Picnic task produced right hemisphere lateralization. Both tasks demonstrated high internal reliability (α >.80). The laterality indices produced by the Magic Hat task correlated with the Word Generation task, ρ =.52, p =.001. Likewise, the laterality indices produced by the Teddy Bear Picnic task correlated with the Landmark task, ρ =.45, p =.028. Thus, the Magic Hat and Teddy Bear Picnic tasks are reliable and valid measures of language and visuospatial lateralization, suitable for toddlers and young children using fTCD. [ABSTRACT FROM AUTHOR]

Since the ground-breaking discovery that in-egg light exposure triggers the emergence of visual lateralisation, domestic chicks became a crucial model for research on the interaction of environmental and genetic influences for brain development. In domestic chick embryos, light exposure induces neuroanatomical asymmetries in the strength of visual projections from the thalamus to the visual Wulst. Consequently, the right visual Wulst receives more bilateral information from the two eyes than the left one. How this impacts visual Wulst's physiology is still unknown. This paper investigates the visual response properties of neurons in the left and right Wulst of dark- and light-incubated chicks, studying the effect of light incubation on bilaterally responsive cells that integrate information from both eyes. We recorded from a large number of visually responsive units, providing the first direct evidence of lateralisation in the neural response properties of units of the visual Wulst. While we confirm that some forms of lateralisation are induced by embryonic light exposure, we found also many cases of light-independent asymmetries. Moreover, we found a strong effect of in-egg light exposure on the general development of the functional properties of units in the two hemispheres. This indicates that the effect of embryonic stimulation goes beyond its contribution to the emergence of some forms of lateralisation, with influences on the maturation of visual units in both hemispheres. [ABSTRACT FROM AUTHOR]

Laterality patterns of resting state networks (RSN) change in various neuropsychiatric conditions. Multiple sclerosis (MS) causes neuro-cognitive symptoms involving dysfunctional large-scale brain networks. Yet, whether healthy laterality patterns of RSNs are maintained in MS and whether altered laterality patterns explain disease symptoms has not been explicitly investigated. We analysed functional MRI and diffusion tensor imaging data from 24 relapsing–remitting MS patients and 25 healthy participants. We performed group-level independent component analysis and used dual regression to estimate individual versions of well-established RSNs. Voxelwise laterality indices were calculated for each RSN. Group differences were assessed via a general linear model-based approach. The relationship between functional laterality and white matter microstructural asymmetry was assessed using Tract-Based Spatial Statistics. Spearman's correlation was calculated between laterality indices and Brief International Cognitive Assessment for Multiple Sclerosis scores. Functional laterality of the dorsal attention network showed a significant leftward shift in the MS group in the posterior intraparietal sulcus (p < 0.033). Default-mode network laterality showed a significant leftward shift in the MS group in the angular gyrus (p < 0.005). Diminished dorsal attention network laterality was associated with increased fractional anisotropy asymmetry in the superior longitudinal fasciculus (p < 0.02). In the default-mode network, leftward laterality of the angular gyrus was associated with higher BVMT-R scores (R = − 0.52, p < 0.023). Our results confirm previous descriptions of RSN dysfunction in relapsing–remitting MS and show that altered functional connectivity lateralisation patterns of RSNs might contibute to cognitive performance and structural remodellation even in patients with mild clinical symptoms. [ABSTRACT FROM AUTHOR]

Ageing leads to a decline in white matter microstructure and dexterous function of the hand. In adolescents, it has previously been shown that the degree of right-left asymmetry in the corticospinal tract (CST) is linearly related with right-left asymmetry in dexterity. Here, we tested whether this association is also expressed in older adults. Participants completed a simple circle drawing task with their right and left hand as a measure of dexterity and underwent whole-brain diffusion weighted imaging at 3 Tesla (n = 199; aged 60–72 years). Fractional anisotropy and mean diffusivity of right and left CST were extracted from a manually defined region-of-interest. Linear regression analyses were computed to replicate the analyses in adolescents. Frequentist analyses were complemented with a Bayesian analytical framework. Outcome measures were compared with those previously reported in adolescents (aged 11–16 years). Asymmetries in white matter microstructure of the CST were evident and comparable to the degree of lateralisation observed in adolescence. Similarly, asymmetries in dexterity were evident, but to a lesser degree than in adolescents. Unlike in adolescents, we found no evidence of a linear relationship between asymmetries in CST microstructure and dexterity. Complementary Bayesian regression analysis provided moderate evidence in favour of the null hypothesis, pointing towards a lack of association between the structural and functional measures of right-left asymmetry. Our findings are compatible with the notion that, by late adulthood, a diverging impact of age on white matter structure and dexterous hand function dilutes the structure-function relationship between CST microstructure and manual proficiency that has been reported in adolescents.

Introduction: Approximately 30% of patients with mesial temporal lobe epilepsy (MTLE) will develop drug resistance, which requires early surgical treatment. The success of the surgical procedure largely depends on the correct lateralisation of the epileptogenic zone, which can only be determined in 70% of patients with such conventional diagnostic tools as video electroencephalography and volumetric structural magnetic resonance imaging. We evaluated the performance of a memory functional magnetic resonance imaging (fMRI) paradigm in lateralising the epileptogenic zone in patients with drug-resistant MTLE., Methods: We included 18 patients with MTLE attended at the Instituto Neurológico Colombiano in Medellin (Colombia) between 2018 and 2019. The volume of functional activation in both temporal lobes was determined with a memory fMRI paradigm. A concordance analysis was performed to compare the performance of fMRI against that of conventional tests., Results: In patients with left MTLE, lower total activation was found in the hemisphere ipsilateral to the epileptogenic zone as compared to the contralateral hemisphere (121.15 ± 16.48 voxels vs 170.23 ± 17.8 voxels [P < .001]), showing substantial concordance with conventional tests. Patients with right MTLE displayed lower hippocampal activation ipsilateral to the epileptogenic zone (18.5 ± 3.38 voxels vs 27.8 ± 3.77 voxels in the contralateral hippocampus [P = .048]), showing moderate concordance with conventional tests., Conclusions: These findings suggest that lower functional activation as determined by a memory fMRI paradigm has a high level of concordance with conventional tests for lateralising the epileptogenic zone in patients with drug-resistant MTLE., (Copyright © 2022 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.)

Objective: Benign paroxysmal positional vertigo (BPPV) is poorly reported in developing countries. This study aimed at determining the prevalence, aetiology, and comorbid illnesses of benign paroxysmal positional vertigo in our center. Materials and Methods: This was a prevalence hospital-based study of all patients with the diagnosis of benign paroxysmal positional vertigo (BPPV). Pretested interviewer assisted questionnaire was administered to obtain data. Otoscopic examination, otoneurologic review, followed by mandatory Dix Hallpike maneuver and supine roll test was performed on all patients to diagnose posterior, lateral or anterior canal benign paroxysmal positional vertigo. All the data obtained were collated and analyzed by using SPSS version 16.0. Results: Prevalence was 1.9%. Peak prevalence of 37.0% was at age group 41–50 years. Male accounted for 46.1% with male to female ratio of 1:1.2. Benign paroxysmal positional vertigo accounted for 62.3% urban dwellers, 33.1% postsecondary education, 39.6% Civil servant and 33.8% married. There were 99.4% unilateral and 64.3% right benign paroxysmal positional vertigo. Idiopathic was 70.1% while trauma, migraine, and inner ear disorder were 20.8%, 7.1%, and 1.9%, respectively. Benign paroxysmal positional vertigo was 66.2% posterior semicircular canal followed by 24.7% lateral semicircular canal and 0.6% anterior semicircular canal. Commonly associated comorbid illnesses were visual disorder, hypertension, arthritis, and diabetes mellitus in 27.9%, 23.4%, 22.1%, and 2.6%, respectively. Conclusion: Benign paroxysmal positional vertigo is common otologic disorder. It is associated with significant comorbid illnesses. Early detection will reduce morbidity and mortality. Improvement in the level of health care at primary level and health education to create awareness among the populace is to be encouraged.

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The present study explored the relationships between the personality traits boldness, activity, exploration, and sociability, and lateralized utilisation of brain hemispheres in the hatchery-reared juveniles of Deccan Mahseer (Tor khudree), an endangered megafish inhabiting the rivers of central and southern India. Our results revealed a significant positive correlation between boldness, activity and exploratory traits in this species when tested in isolation. Boldness was also positively correlated with the time spent near a conspecific individual, but not with an alien invasive heterospecific tilapia (Oreochromis mossambicus). Although juvenile Deccan Mahseer exhibited significantly greater preference towards conspecific over heterospecific, no divergence in the utilisation of right or left eye was seen while observing these individuals, suggesting the lack of lateralised utilisation of brain hemispheres. Furthermore, laterality in visual perception did not show any significant correlation with any of the personality traits tested in this species. Positive correlations between boldness and sociability in hatchery-reared mahseer populations could result in divergent patterns of dispersion, while absence of laterality may reflect cognitive deficits induced by homogeneous rearing conditions. A greater understanding of such behavioural patterns could help improve rearing practices and inform release protocols for the purposes of conservation of this endangered species. [ABSTRACT FROM AUTHOR]

Chameleons (Chamaeleonidae, Reptilia) are known for their extreme sensory and motor adaptations to arboreal life and insectivoury. They show most distinct sequences of visuo-motor patterns in threat avoidance and in predation with prey capture being performed by tongue strikes that are unparalleled in vertebrates. Optical adaptations result in retinal image enlargement and the unique capacity to determine target distance by accommodation cues. Ocular adaptations result in complex eye movements that are context dependent, not independent, as observed in threat avoidance and predation. In predation, evidence from the chameleons' capacity to track multiple targets support the view that their eyes are under individual controls. Eye movements and body movements are lateralised, with lateralisation being a function of many factors at the population, individual, and specific-situation levels. Chameleons are considered a potentially important model for vision in non-mammalian vertebrates. They provide exceptional behavioural tools for studying eye movements as well as information gathering and analysis. They open the field of lateralisation, decision making, and context dependence. Finally, chameleons allow a deeper examination of the relationships between their unique visuo-motor capacities and the central nervous system of reptiles and ectotherms, in general, as compared with mammals. [ABSTRACT FROM AUTHOR]

Copyright of Medical Rehabilitation / Rehabilitacja Medyczna is the property of Medical Rehabilitation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An accurate perception of the space surrounding us is central for effective and safe everyday functioning. Understanding the factors influencing spatial perception is therefore vital. Here, we first confirm previous reports that our cultural reading habits shape the perception of space. Twenty-four left-to-right readers (tested in Australia) and 23 right-to-left readers (tested in Israel) over-attend to information presented on the left and right side of space, respectively. We then show that this cultural bias is highly malleable. By employing a simple mirror-reading task prior to the spatial judgments, we demonstrate that the supposed cultural bias can be easily overridden. These findings question hardwired, lateralisation models of spatial-attentional biases and highlight the need for a dynamic model that takes into account hemispheric lateralisation, cultural habits and situational context. [ABSTRACT FROM AUTHOR]

Purpose: Although lateralisation errors (LEs) are a common speech sound disorder, no studies have examined their early development. The purpose of this exploratory small-scale investigation was to compare the early (birth–24 months) speech sound development between children later diagnosed with LEs and typically developing children. Method: This was a between-group case-controlled design with six monolingual English-speaking participants. Participants were White, non-Hispanic girls with at least one college-educated parent. As children, three had been diagnosed with lateralisation speech sound errors and three demonstrated typical speech sound development. Participants' parents provided home video-recordings of the participants as infants/toddlers between birth and age 2. These videos were then analysed for the amount, type and diversity of sounds, and canonical babbling onset. Result: There was no statistically significant between-group difference in the volubility (i.e. combined frequency of non-resonant and resonant utterances) or in the age at which [s] or [z] emerged. However, infants/toddlers who were later diagnosed with LEs showed reduced frequency/minute in production of resonant utterances and consonants (including [s, z]), used fewer different consonants/minute, and used fewer syllable shapes/minute compared to typically developing infants/toddlers. At 7–12 months, none of the infants/toddlers later diagnosed with LEs, but all participants in the comparison group had reached the canonical babbling stage. Conclusion: Children who have LEs may have had a less robust speech sound system as infants/toddlers than their typically developing peers. However, these findings must be considered with caution due to the significant limitations of this investigation. [ABSTRACT FROM AUTHOR]

In epilepsy patients, language lateralisation is an important part of the presurgical diagnostic process. Using task-based fMRI, language lateralisation can be determined by visual inspection of activity patterns or by quantifying the difference in left- and right-hemisphere activity using variations of a basic formula [(L–R)/(L+R)]. However, the values of this laterality index (LI) depend on the choice of activity thresholds and regions of interest. The diagnostic utility of the LI also depends on how its continuous values are translated into categorical decisions about a patient's language lateralisation. Here, we analysed fMRI data from 712 epilepsy patients who performed a verbal fluency task. Each fMRI data set was evaluated by a trained human rater as depicting left-sided, right-sided, or bilateral lateralisation or as being inconclusive. We used data-driven methods to define the activity thresholds and regions of interest used for LI computation and to define a classification scheme that allowed us to translate the LI values into categorical decisions. By deconstructing the LI into measures of laterality (L–R) and strength (L+R), we also modelled the relationship between activation strength and conclusiveness of a data set. In a held-out data set, predictions reached 91% correct when using only conclusive data and 82% when inconclusive data were included. Although only trained on human evaluations of fMRIs, the approach generalised to the prediction of language Wada test results, allowing for significant above-chance accuracies. Compared against different existing methods of LI-computation, our approach improved the identification and exclusion of inconclusive cases and ensured that decisions for the remaining data could be made with consistently high accuracies. We discuss how this approach can support clinicians in assessing fMRI data on a single-case level, deciding whether lateralisation can be determined with sufficient certainty or whether additional information is needed.

Functional magnetic resonance imaging (fMRI) is an established eloquent cortex mapping technique that is now an integral part of the pre-operative work-up in candidates for epilepsy surgery. Emerging evidence in adults with epilepsy suggests that material-specific fMRI paradigms can predict postoperative memory outcomes, however these paradigms are not suitable for children. In pediatric age, the use of memory fMRI paradigms designed for adults is complicated by the effect of developmental stages in cognitive maturation, the impairment experienced by some people with temporal lobe epilepsy (TLE) and the normal representation of memory function during development, which may differ from adults. We present a memory fMRI paradigm designed to activate mesial temporal lobe structures that is brief, independent of reading ability, and therefore a novel candidate for use in children. Data from 33 adults and 19 children (all healthy controls) show that the paradigm captures the expected leftward asymmetry of mesial temporal activation in adults. A more symmetrical pattern was observed in children, consistent with the progressive emergence of hemispheric specialisation across childhood. These data have important implications for the interpretation of presurgical memory fMRI in the pediatric setting. They also highlight the need to carefully consider the impact of cognitive development on fMRI tools used in clinical practice. [ABSTRACT FROM AUTHOR]

Disruption to language lateralisation has been proposed as a cause of developmental language impairments. In this study, we tested the idea that consistency of lateralisation across different language functions is associated with language ability. A large sample of adults with variable language abilities (N = 67 with a developmental disorder affecting language and N = 37 controls) were recruited. Lateralisation was measured using functional transcranial Doppler sonography (fTCD) for three language tasks that engage different language subprocesses (phonological decision, semantic decision and sentence generation). The whole sample was divided into those with consistent versus inconsistent lateralisation across the three tasks. Language ability (using a battery of standardised tests) was compared between the consistent and inconsistent groups. The results did not show a significant effect of lateralisation consistency on language skills. However, of the 31 individuals showing inconsistent lateralisation, the vast majority (84%) were in the disorder group with only five controls showing such a pattern, a difference that was higher than would be expected by chance. The developmental disorder group also demonstrated weaker correlations between laterality indices across pairs of tasks. In summary, although the data did not support the hypothesis that inconsistent language lateralisation is a major cause of poor language skills, the results suggested that some subtypes of language disorder are associated with inefficient distribution of language functions between hemispheres. Inconsistent lateralisation could be a causal factor in the aetiology of language disorder or may arise in some cases as the consequence of developmental disorder, possibly reflective of compensatory reorganisation. [ABSTRACT FROM AUTHOR]

Previous research has established that the left cerebral hemisphere is dominant for the control of continuous bimanual movements. The lateralisation of motor control for discrete bimanual movements, in contrast, is underexplored. The purpose of the current study was to investigate which (if either) hemisphere is dominant for discrete bimanual movements. Twenty-one participants made bimanual reach-to-grasp movements towards pieces of candy. Participants grasped the candy to either place it in their mouths (grasp-to-eat) or in a receptacle near their mouths (grasp-to-place). Research has shown smaller maximum grip apertures (MGAs) for unimanual grasp-to-eat movements than unimanual grasp-to-place movements when controlled by the left hemisphere. In Experiment 1, participants made bimanual symmetric movements where both hands made grasp-to-eat or grasp-to-place movements. We hypothesised that a left hemisphere dominance for bimanual movements would cause smaller MGAs in both hands during bimanual grasp-to-eat movements compared to those in bimanual grasp-to-place movements. The results revealed that MGAs were indeed smaller for bimanual grasp-to-eat movements than grasp-to-place movements. This supports that the left hemisphere may be dominant for the control of bimanual symmetric movements, which agrees with studies on continuous bimanual movements. In Experiment 2, participants made bimanual asymmetric movements where one hand made a grasp-to-eat movement while the other hand made a grasp-to-place movement. The results failed to support the potential predictions of left hemisphere dominance, right hemisphere dominance, or contralateral control. [ABSTRACT FROM AUTHOR]

Objective: Benign paroxysmal positional vertigo (BPPV) is poorly reported in developing countries. This study aimed at determining the prevalence, aetiology, and comorbid illnesses of benign paroxysmal positional vertigo in our center. Materials and Methods: This was a prevalence hospital-based study of all patients with the diagnosis of benign paroxysmal positional vertigo (BPPV). Pretested interviewer assisted questionnaire was administered to obtain data. Otoscopic examination, otoneurologic review, followed by mandatory Dix Hallpike maneuver and supine roll test was performed on all patients to diagnose posterior, lateral or anterior canal benign paroxysmal positional vertigo. All the data obtained were collated and analyzed by using SPSS version 16.0. Results: Prevalence was 1.9%. Peak prevalence of 37.0% was at age group 41–50 years. Male accounted for 46.1% with male to female ratio of 1:1.2. Benign paroxysmal positional vertigo accounted for 62.3% urban dwellers, 33.1% postsecondary education, 39.6% Civil servant and 33.8% married. There were 99.4% unilateral and 64.3% right benign paroxysmal positional vertigo. Idiopathic was 70.1% while trauma, migraine, and inner ear disorder were 20.8%, 7.1%, and 1.9%, respectively. Benign paroxysmal positional vertigo was 66.2% posterior semicircular canal followed by 24.7% lateral semicircular canal and 0.6% anterior semicircular canal. Commonly associated comorbid illnesses were visual disorder, hypertension, arthritis, and diabetes mellitus in 27.9%, 23.4%, 22.1%, and 2.6%, respectively. Conclusion: Benign paroxysmal positional vertigo is common otologic disorder. It is associated with significant comorbid illnesses. Early detection will reduce morbidity and mortality. Improvement in the level of health care at primary level and health education to create awareness among the populace is to be encouraged. [ABSTRACT FROM AUTHOR]

In epilepsy patients, language lateralisation is an important part of the presurgical diagnostic process. Using task-based fMRI, language lateralisation can be determined by visual inspection of activity patterns or by quantifying the difference in left- and right-hemisphere activity using variations of a basic formula [(L–R)/(L+R)]. However, the values of this laterality index (LI) depend on the choice of activity thresholds and regions of interest. The diagnostic utility of the LI also depends on how its continuous values are translated into categorical decisions about a patient's language lateralisation. Here, we analysed fMRI data from 712 epilepsy patients who performed a verbal fluency task. Each fMRI data set was evaluated by a trained human rater as depicting left-sided, right-sided, or bilateral lateralisation or as being inconclusive. We used data-driven methods to define the activity thresholds and regions of interest used for LI computation and to define a classification scheme that allowed us to translate the LI values into categorical decisions. By deconstructing the LI into measures of laterality (L–R) and strength (L+R), we also modelled the relationship between activation strength and conclusiveness of a data set. In a held-out data set, predictions reached 91% correct when using only conclusive data and 82% when inconclusive data were included. Although only trained on human evaluations of fMRIs, the approach generalised to the prediction of language Wada test results, allowing for significant above-chance accuracies. Compared against different existing methods of LI-computation, our approach improved the identification and exclusion of inconclusive cases and ensured that decisions for the remaining data could be made with consistently high accuracies. We discuss how this approach can support clinicians in assessing fMRI data on a single-case level, deciding whether lateralisation can be determined with sufficient certainty or whether additional information is needed. [ABSTRACT FROM AUTHOR]

Highlights • Male zebra finches were exposed to own-offspring odour or neutral odour. • Offspring odour caused changes in arousal (head saccades). • Brain activity was measured by immediate early gene (c-Fos) expression. • Social odour activated hippocampus in a lateralised way. Abstract Experiments from our research group have demonstrated that the olfactory sense of birds, which has been considered as unimportant for a long time, plays a prominent role as communication channel in social behaviour. Odour cues are used e.g. by zebra finch chicks to recognize the mother, by adult birds to distinguish their own eggs from others, or to recognize kin. While there is quite a lot of evidence for the importance of odour for social behaviour, it is not known as yet which brain areas may be involved in the processing of socially relevant odours. We therefore compared the brain activation pattern of zebra finch males exposed to their own offspring odour with that induced by a neutral odour stimulus. By measuring head saccade changes as behavioural reaction and using the expression of the immediate early gene product c-Fos as brain activity marker, we show here that the activation pattern, namely the activity difference between the left and the right hemisphere, of several hippocampal areas in zebra finch males is altered by the presentation of the odour of their own nestlings. In contrast, the nucleus taeniae of the amygdala (TnA) exhibits a tendency of a reduction of c-Fos activation in both hemispheres as a consequence of exposure to the nestling odour. We conclude that the hippocampus is involved in odour based processing of social information, while the role of TnA remains unclear. [ABSTRACT FROM AUTHOR]

FMRI-based laterality index (LI) is widely used to assess relative left–right differences in brain function. Here we investigated objective ways to generate categorical LI. By defining left and right hemisphere contributions as discrete random variables, it was possible to depict the probability mass function of LI. Its distribution has a shape of a symmetrical truncated exponential function. We demonstrate that LI = ± 0.2 is an objective cut-off to categorize classification of hemispheric dominance. We then searched for parallels between LI and classic similarity or association indices. A parallel between LI and Sorensen–Dice index can be established under maximal voxel-wise overlap between left and right hemispheres. To redefine LI as a proper distance metric, we suggest instead to relate LI to Jaccard–Tanimoto similarity index. Accordingly, a new LI formula can be derived: LInew = LH–RH/max(LH,RH). Using this new formula, all LInew values follow a uniform-like distribution, and optimal categorization of hemispheric dominance can be achieved at cut-off LInew = ± 1/3. Overall, this study investigated some statistical properties of LI and revealed interesting parallels with classic similarity indices in taxonomy. The theoretical distribution of LI should be taken into account when quantifying any existing bias in empirical distributions of lateralization in healthy or clinical populations. [ABSTRACT FROM AUTHOR]

We here present DiViDu, a research software, which we developed for a dual task experiment with an integrated divided visual field paradigm. The dual task experiment consists of a lexical decision task with different semantic verb categories, and a complex tapping task with either the left or right hand. The software allows researchers the replication of our experiment, as well as the reconfiguration for further dual task experiments with alternative tapping tasks and stimuli (e.g., word classes, semantic classes, task languages) as well as adjusted experimental settings. Furthermore, with only slight modifications to the source code, researchers can implement various new experimental setups including a large variety of language tasks (e.g., silent and aloud reading, naming, verbal fluency) and non-verbal tasks. The software DiViDu is implemented using the .NET framework and is available under the Apache 2 License on GitHub (https://github.com/dividu/dividu). Funding statement: The publication of the paper was supported by the Open Access Publication Fund of the University of Konstanz.

The capability of animals to alter their behaviour in response to novel or familiar stimuli, or behavioural flexibility, is strongly associated with their ability to learn in novel environments. Reptiles are capable of learning complex tasks and offer a unique opportunity to study the relationship between visual proficiency and behavioural flexibility. The focus of this study was to investigate the behavioural flexibility of red-footed tortoises and their ability to perform reversal learning. Reversal learning involves learning a particular discrimination task, after which the previously rewarded cue is reversed and then subjects perform the task with new reward contingencies. Red-footed tortoises were required to learn to recognise and approach visual cues within a Y-maze. Once subjects learned the visual discrimination, tortoises were required to successfully learn four reversals. Tortoises required significantly more trials to reach criterion (80% correct) in the first reversal, indicating the difficulty of unlearning the positive stimulus presented during training. Nevertheless, subsequent reversals required a similar number of sessions to the training stage, demonstrating that reversal learning improved up to a point. All subjects tested developed a position bias within the Y-maze that was absent prior to training, but most were able to exhibit reversal learning. Red-footed tortoises primarily adopted a win-stay choice strategy while learning the discrimination without much evidence for a lose-shift choice strategy, which may explain limits to their behavioural flexibility. However, improving performance across reversals while simultaneously overcoming a position bias provides insights into the cognitive abilities of tortoises. [ABSTRACT FROM AUTHOR]

Copyright of Review of Science Mathematics & ICT Education is the property of Library & Information Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dichotic listening (DL) taps information on the brain's language laterality, processing, and attention. Research has shown that DL responses in dyslexia deviate from the typical pattern. Here, effects of DL training and its correspondence to rapid naming (RAN) and digit span (DS) in typical children and children with dyslexia were assessed. Three groups of third graders participated: two training groups, control training (CT) and dyslexia training (DT), and a control group that received no training (control no training, CnT). All took part in testing pretraining and posttraining. DL measures were on laterality, response scores, and attention. The three groups showed different response patterns: minor changes in CnT, change in all measures in CT, and some changes in DT. RAN and DS scores correlated significantly with some of the DL measures, especially with the attention scores. Our findings support arguments that brain architecture for language in dyslexia is lateralised in the same way as in children without dyslexia. However, the ability to modulate attention during DL is weaker in dyslexia than in typically developing children. A training-induced normalisation of lateralisation was observed in free recall in the dyslexia group, which suggests that DL training may be a promising intervention approach. [ABSTRACT FROM AUTHOR]

Asymmetry of dopaminergic neurodegeneration and subsequent lateralisation of motor symptoms are distinctive features of Parkinson’s disease compared to other forms of neurodegenerative or symptomatic parkinsonism. Even 200 years after the first description of the disease, the underlying causes for this striking clinicopathological feature are not yet fully understood. There is increasing evidence that lateralisation of disease is due to a complex interplay of hereditary and environmental factors that are reflected not only in the concept of dominant hemispheres and handedness but also in specific susceptibilities of neuronal subpopulations within the substantia nigra. As a consequence, not only the obvious lateralisation of motor symptoms occurs but also patterns of associated non-motor signs are defined, which include cognitive functions, sleep behaviour or olfaction. Better understanding of the mechanisms contributing to lateralisation of neurodegeneration and the resulting patterns of clinical phenotypes based on bilateral post-mortem brain analyses and clinical studies focusing on right/left hemispheric symptom origin will help to develop more targeted therapeutic approaches, taking into account subtypes of PD as a heterogeneous disorder. [ABSTRACT FROM AUTHOR]

Background: There is an ongoing debate whether the effect of Melodic Intonation Therapy (MIT) in patients with severe non-fluent aphasia depends on recruitment of right hemisphere (RH) structures for language functioning or on re-recruitment of left hemisphere (LH) language structures. So far, neuroimaging studies have produced conflicting evidence. Aims: To investigate whether a shift in language lateralisation occurs after intensive treatment in subacute (<3 months post onset) and chronic (>1 year post onset) stroke patients with aphasia. Method & Procedures: In a multiple case pilot study with pre-post-design 5 subacute and 4 chronic stroke patients received intensive MIT (6 weeks, 30 sessions). Pre- and post-treatment they underwent functional MRI scanning with a passive listening task to determine language lateralisation indices (LIs). Outcomes & Results: No consistent shift of language activation was found either to the LH or to the RH. With one exception, subacute patients showed symmetrical or right-lateralised language activation pretreatment, which tended to become more right lateralised after treatment. Language activation in chronic patients was left lateralised in two of the four participants, with a tendency towards stronger left lateralised activation after treatment. Conclusions: Data for the subacute patients provide some support for the classical notion that MIT promotes recruitment of RH structures for language processing. However, the contrasting activation patterns in chronic participants before as well as after treatment suggest that reorganisation of language after MIT occurs in interaction with a dynamic recovery process after stroke. Time post onset should be addressed systematically in studies of treatment-induced language recovery. [ABSTRACT FROM AUTHOR]