Humanity and the left hemisphere: The story of half a brain

Dobutamine-induced alterations in internal carotid artery blood flow and cerebral blood flow in healthy adults

PURPOSE

Dobutamine, a sympathomimetic agent, is widely used clinically, influencing cardiac output, heart rate (HR), and blood pressure (BP), which may impact cerebral blood flow (CBF), critical for brain metabolism. However, the effects of dobutamine on CBF and internal carotid artery (ICA) blood flow remain unclear, with contradictory reported in both clinical and animal studies. It is necessary to investigate the effects of dobutamine on cervical and cerebral hemodynamics. This study aimed to evaluate the effects of dobutamine infusion on ICA blood flow and CBF, explore their relationship, and identify factors influencing CBF to facilitate timely monitoring in clinical practice.

METHODS

Forty-eight healthy volunteers underwent physiological assessment, ICA ultrasound, and brain magnetic resonance imaging (MRI) data before and after the administration of dobutamine. Paired t and Wilcoxon signed-rank tests were used to analyze changes, while logistic regression explored associations between hemodynamic factors and CBF.

RESULTS

Dobutamine infusion significantly increased HR, respiration rate, systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure, while blood oxygen remained stable. Compared with those in the resting state, the peak systolic velocity (Vs), resistance index, pulsatility index, and systolic/diastolic ratio (S/D) increased, whereas end-diastolic velocity (Vd) decreased. ICA diameter and mean velocity showed no significant changes. CBF significantly decreased in the anterior and middle cerebral arteries. Logistic regression identified SBP, DBP, and S/D difference as key factors associated with CBF reduction.

CONCLUSIONS

Dobutamine altered ICA hemodynamics and reduced CBF in anterior and middle cerebral arteries. Real-time ICA ultrasound monitoring provides valuable guidance during clinical use.

Clinical efficacy and therapeutic mechanism of active 'five-tone' speech therapy compared with conventional speech-language therapy for treatment of post-stroke aphasia: protocol for a randomised controlled trial

INTRODUCTION

Aphasia is a common dysfunction among patients with stroke that can severely affect daily life. Listening to the 'five-tone' melodies of traditional Chinese medicine can improve some of the language functions of patients with post-stroke aphasia; however, passive listening may limit its clinical efficacy. In this study, we transform the passive listening five-tone melodic therapy of traditional Chinese medicine into an active five-tone speech therapy. This randomised controlled trial aims to investigate the clinical efficacy of active five-tone speech therapy in the treatment of post-stroke aphasia, such as language function, daily communication ability and communication efficiency, as well as investigate the therapeutic mechanism of this innovative therapy by electroencephalogram and MRI.

METHODS AND ANALYSIS

The study is a multicentric, randomised, parallel-assignment, single-blind treatment study. 70 participants will be recruited from the Rehabilitation Hospital Affiliated to Fujian University of Traditional Chinese Medicine and the Third People's Hospital Affiliated to Fujian University of Traditional Chinese Medicine and randomly assigned to two groups, the five-tone speech therapy group and the control group, at a 1:1 ratio. The control group will receive 20 sessions of conventional speech-language therapy, while the five-tone speech therapy group will receive 20 sessions of five-tone speech therapy in addition to conventional speech-language therapy. The primary outcome measure for this study will be the score on Western Aphasia Battery. Secondary outcomes include communicative abilities in daily living, percentage of correct information units and correct information units per minute, as well as resting-state electroencephalogram, event-related potentials and MRI data. All outcomes will be evaluated at 0 weeks (before intervention) and at 4 weeks (after 20 intervention sessions).

ETHICS AND DISSEMINATION

Ethical approval of this study was granted by the ethics committees of the Rehabilitation Hospital Affiliated to Fujian University of Traditional Chinese Medicine (2023KY-009-01) and the Third People's Hospital Affiliated to Fujian University of Traditional Chinese Medicine (2023-kl-010). Recruitment commenced on 24 April 2023. Informed consent will be obtained from all participants of the trial (or from their legal guardians, where applicable). The outcomes of the trial will be disseminated through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ChiCTR2300069257.

Does the right hemisphere retain functional characteristics typical of the emotional adaptive system? An evolutionary approach to the problem of brain asymmetries

The right and left hemispheres host two complementary adaptive systems with a right-sided prevalence of automatic and unconscious processing modes, typical of the 'emotional system', and a left-sided prevalence of propositional and conscious processing modes typical of the 'cognitive system' The principal right hemispheric syndromes (and the functioning modes typical of this hemisphere) are, indeed, characterized by automatic and unconscious processing modalities. Thus, the unilateral neglect syndrome discloses a defective automatic (and spared intentional) spatial orienting of attention; face and voice recognition disorders are due to disruption of mechanisms that automatically generate familiarity feelings and anosognosia seems due to the unconscious loss of personal significance attributed by the patient to the pathological event. Since emotions were the only adaptive system existing before the development of language (which is provided of a strong capacity to develop and shape cognition), the persistence in the right hemisphere of mechanisms typical of the emotional system strongly supports an evolutionary model of brain laterality. (160 words).

Envisioning the future: An ALE meta-analysis on neural correlates of future thinking, prospective memory and delay discounting

Our representations of the future are processed in the service of several different cognitive functions, including episodic future thinking, prospective memory, and temporal discounting. The present meta-analysis used the Activation Likelihood Estimation method to understand whether there is a core network underlying future-oriented cognition and to identify the specific brain regions that support future-related processes in each function. Following the PRISMA guidelines, a total of 24, 19, and 27 neuroimaging studies were included for future thinking, prospective memory, and temporal discounting, respectively. Results showed that there is no specific region or network for the future. Instead, the 'future' seems to be represented on an anterior-posterior tangibility gradient, based on the level of abstractness/concreteness of the simulated scenario. Additionally, future-oriented cognition is mediated by two distinct networks: the Default Network and the Salience Network. The Default Network is mainly active in supporting future thinking, whereas the Salience Network is primarily involved in prospective memory and delay discounting.

Taking Sides: Asymmetries in the Evolution of Human Brain Development in Better Understanding Autism Spectrum Disorder

Confirmation from structural, functional, and behavioral studies agree and suggest a configuration of atypical lateralization in individuals with autistic spectrum disorders (ASD). It is suggested that patterns of cortical and behavioral atypicality are evident in individuals with ASDs with atypical lateralization being common in individuals with ASDs. The paper endeavors to better understand the relationship between alterations in typical cortical asymmetries and functional lateralization in ASD in evolutionary terms. We have proposed that both early genetic and/or environmental influences can alter the developmental process of cortical lateralization. There invariably is a “chicken or egg” issue that arises whether atypical cortical anatomy associated with abnormal function, or alternatively whether functional atypicality generates abnormal structure.

Brain regions involved in fractional amplitude of low-frequency fluctuation in cluster headache patients: a resting-state functional MRI study

BACKGROUND

We used resting-state functional magnetic resonance imaging (RS-fMRI) to assess the possible pathogenic role of fALFF in CH. A limited number of studies have reported on fractional amplitude of low-frequency fluctuation (fALFF) in cluster headache (CH).

METHODS

RS-fMRI scans of 23 patients with CH were obtained (11with left-sided headache and 12 with right-sided headache), along with scans of 23 age- and sex-matched normal controls. The RS-fMRI data were analyzed to explore abnormal brain activity in the left CH and right CH patients during the non-painful state in one cluster period. fALFF was compared between patients and controls, and correlation analysis between the regional mean fALFF values and clinical characteristics was performed.

RESULTS

A decrease in fALFF was detected in the left cerebellum, left lentiform nucleus, left frontal lobe, left anterior cingulate, and right postcentral gyrus in the left CH group compared to the controls, while a decrease of fALFF was detected in the right cerebellum, right cingulate gyrus, right superior parietal lobule, right inferior parietal lobule, right postcentral gyrus, and left precuneus in the right CH group. No patient had a region with increased fALFF. A moderate correlation was observed between some regional mean fALFF values and the clinical characteristics.

CONCLUSIONS

We deduced that dysfunction in multiple brain areas is involved in the non-painful state of CH during a cluster period.

The Topology of Pediatric Structural Asymmetries in Language-Related Cortex

Structural asymmetries in language-related brain regions have long been hypothesized to underlie hemispheric language laterality and variability in language functions. These structural asymmetries have been examined using voxel-level, gross volumetric, and surface area measures of gray matter and white matter. Here we used deformation-based and persistent homology approaches to characterize the three-dimensional topology of brain structure asymmetries within language-related areas that were defined in functional neuroimaging experiments. Persistence diagrams representing the range of values for each spatially unique structural asymmetry were collected within language-related regions of interest across 212 children (mean age (years) = 10.56, range 6.39–16.92; 39% female). These topological data exhibited both leftward and rightward asymmetries within the same language-related regions. Permutation testing demonstrated that age and sex effects were most consistent and pronounced in the superior temporal sulcus, where older children and males had more rightward asymmetries. While, consistent with previous findings, these associations exhibited small effect sizes that were observable because of the relatively large sample. In addition, the density of rightward asymmetry structures in nearly all language-related regions was consistently higher than the density of leftward asymmetric structures. These findings guide the prediction that the topological pattern of structural asymmetries in language-related regions underlies the organization of language.

Brain Size Associated with Foot Preferences in Australian Parrots

Since foot preference of cockatoos and parrots to hold and manipulate food and other objects has been associated with better ability to perform certain tasks, we predicted that either strength or direction of foot preference would correlate with brain size. Our study of 25 psittacine species of Australia found that species with larger absolute brain mass have stronger foot preferences and that percent left-footedness is correlated positively with brain mass. In a sub-sample of 11 species, we found an association between foot preference and size of the nidopallial region of the telencephalon, an area equivalent to the mammalian cortex and including regions with executive function and other higher-level functions. Our analysis showed that percent left-foot use correlates positively and significantly with size of the nidopallium relative to the whole brain, but not with the relative size of the optic tecta. Psittacine species with stronger left-foot preferences have larger brains, with the nidopallium making up a greater proportion of those brains. Our results are the first to show an association between brain size and asymmetrical limb use by parrots and cockatoos. Our results support the hypothesis that limb preference enhances brain capacity and higher (nidopallial) functioning.

There are More than Two Sides to Antisocial Behavior: The Inextricable Link between Hemispheric Specialization and Environment

Human functions and traits are linked to cerebral networks serving different emotional and cognitive control systems, some of which rely on hemispheric specialization and integration to promote adaptive goal-directed behavior. Among the neural systems discussed in this context are those underlying pro- and antisocial behaviors. The diverse functions and traits governing our social behavior have been associated with lateralized neural activity. However, as with other complex behaviors, specific hemispheric roles are difficult to elucidate. This is due largely to environmental and contextual influences, which interact with neural substrates in the development and expression of pro and antisocial functions. This paper will discuss the reciprocal ties between environmental factors and hemispheric functioning in the context of social behavior. Rather than an exhaustive review, the paper will attempt to familiarize readers with the prominent literature and primary questions to encourage further research and in-depth discussion in this field.