Brains of verbal memory specialists show anatomical differences in language, memory and visual systems

The Spectrum of Neurological and Sensory Abnormalities in Gaucher Disease Patients: A Multidisciplinary Study (SENOPRO)

Gaucher disease (GD) has been increasingly recognized as a continuum of phenotypes with variable neurological and sensory involvement. No study has yet specifically explored the spectrum of neuropsychiatric and sensory abnormalities in GD patients through a multidisciplinary approach. Abnormalities involving the nervous system, including sensory abnormalities, cognitive disturbances, and psychiatric comorbidities, have been identified in GD1 and GD3 patients. In this prospective study, named SENOPRO, we performed neurological, neuroradiological, neuropsychological, ophthalmological, and hearing assessments in 22 GD patients: 19 GD1 and 3 GD3. First, we highlighted a high rate of parkinsonian motor and non-motor symptoms (including high rates of excessive daytime sleepiness), especially in GD1 patients harboring severe glucocerebrosidase variants. Secondly, neuropsychological evaluations revealed a high prevalence of cognitive impairment and psychiatric disturbances, both in patients initially classified as GD1 and GD3. Thirdly, hippocampal brain volume reduction was associated with impaired short- and long-term performance in an episodic memory test. Fourthly, audiometric assessment showed an impaired speech perception in noise in the majority of patients, indicative of an impaired central processing of hearing, associated with high rates of slight hearing loss both in GD1 and GD3 patients. Finally, relevant structural and functional abnormalities along the visual system were found both in GD1 and GD3 patients by means of visual evoked potentials and optical coherence tomography. Overall, our findings support the concept of GD as a spectrum of disease subtypes, and support the importance of in-depth periodic monitoring of cognitive and motor performances, mood, sleep patterns, and sensory abnormalities in all patients with GD, independently from the patient's initial classification.

Hippocampal Asymmetry of Regional Development and Structural Covariance in Preterm Neonates

Premature birth is associated with a high prevalence of neurodevelopmental impairments in surviving infants. The hippocampus is known to be critical for learning and memory, yet the putative effects of hippocampal dysfunction remain poorly understood in preterm neonates. In particular, while asymmetry of the hippocampus has been well noted both structurally and functionally, how preterm birth impairs hippocampal development and to what extent the hippocampus is asymmetrically impaired by preterm birth have not been well delineated. In this study, we compared volumetric growth and shape development in the hippocampal hemispheres and structural covariance (SC) between hippocampal vertices and cortical thickness in cerebral cortex regions between two groups. We found that premature infants had smaller volumes of the right hippocampi only. Lower thickness was observed in the hippocampal head in both hemispheres for preterm neonates compared with full-term peers, though preterm neonates exhibited an accelerated age-related change of hippocampal thickness in the left hippocampi. The SC between the left hippocampi and the limbic lobe of the premature infants was severely impaired compared with the term-born neonates. These findings suggested that the development of the hippocampus during the third trimester may be altered following early extrauterine exposure with a high degree of asymmetry.

Extensive long-term verbal memory training is associated with brain plasticity

The human brain has a remarkable capacity to store a lifetime of information through visual or auditory routes. It excels and exceeds any artificial memory system in mixing and integrating multiple pieces of information encoded. In this study, a group of verbal memory experts was evaluated by multiple structural brain analysis methods to record the changes in the brain structure. The participants were professional Hindu pandits (priests/scholars) trained in reciting Vedas and other forms of Hindu scriptures. These professional Vedic priests are experts in memorization and recitation of oral texts with precise diction. Vedas are a collection of hymns. It is estimated that there are more than 20,000 mantras and shlokas in the four Vedas. The analysis included the measurement of the grey and white matter density, gyrification, and cortical thickness in a group of Vedic pandits and comparing these measures with a matched control group. The results revealed an increased grey matter (GM) and white matter (WM) in the midbrain, pons, thalamus, parahippocampus, and orbitofrontal regions in pandits. The whole-brain corelation analysis using length of post-training  teaching duration showed significant correlation with the left angular gyrus. We also found increased gyrification in the insula, supplementary motor area, medial frontal areas, and increased cortical thickness (CT) in the right temporal pole and caudate regions of the brain. These findings, collectively, provide unique information regarding the association between crucial memory regions in the brain and long-term practice of oral recitation of scriptures from memory with the proper diction that also involved controlled breathing.

"First-episode psychosis: Structural covariance deficits in salience network correlate with symptoms severity"

BACKGROUND

Patterns of coordinated variations of gray matter (GM) morphology across individuals are promising indicators of disease. However, it remains unclear if they can help characterize first-episode psychosis (FEP) and symptoms' severity.

METHODS

Sixty-seven FEP and 67 matched healthy controls (HC) were assessed with structural MRI to evaluate the existence of distributed GM structural covariance patterns associated to brain areas belonging to salience network. Voxel-based morphometry (VBM) and structural covariance differences, investigated with salience network seed-based Partial Least Square, were applied to explore differences between groups. GM density associations with Raven's intelligent quotient (IQ) and Positive and Negative Syndrome Scale (PANSS) scores were investigated.

RESULTS

Univariate VBM results gave trend without significant GM differences across groups. GM and IQ correlated positively in both groups: in FEP, mostly in hippocampus, insula, and fronto-temporal structures, while in HC mostly in amygdala, thalamus and fronto-temporal regions. GM and PANSS scores correlated negatively in FEP, with widespread clusters located in limbic regions. Multivariate analysis showed strong and opposite structural GM covariance with salience network for FEP and HC. Moreover, structural covariance of the salience network in FEP correlated negatively with severity of clinical symptoms.

CONCLUSION

Our study provides evidence supporting the insular dysfunction model of psychosis. Reduced structural GM covariance of the salience network, with its association to symptom's severity, appears a promising morphometry feature for FEP detection.

Tantra and Modern Neurosciences: Is there any Correlation?

BACKGROUND AND AIMS

Many studies have conclusively proven that meditative techniques derived from the Indian systems of philosophy, meditation and ritual classified as "Tantra" can bring about sustained changes in the structure and function of the nervous system of practitioners. The aim of this study is to provide neuroscientists a framework through which to interpret Tantra, and thereby provide a foundation upon which future interdisciplinary study can be built.

METHODS

We juxtapose Tantric concepts such as the subtle body, nadis and mantras with relevant neuroscientific findings. Our premise is that through sustained internalization of attention, Tantric practitioners were able to identify and document subtle changes in their field of awareness, which usually do not cross the threshold to come into our perception.

RESULTS

The descriptions left by Tantric philosophers are often detailed and empirical, but they are about subjective phenomena, rather than external objects. They also focus on individual experiences, rather than the group-level analyses favored by modern medical science.

CONCLUSION

Systematic exploration of Tantric texts can be of tremendous value in expanding our understanding of human beings' experiential reality, by enabling us to build bridges between first-person and third-person approaches to the nervous system. This may open up new avenues for cognitive enhancement and treating neurological diseases.

Cerebellar Lobules Optimal Stimulation (CLOS): A Computational Pipeline to Optimize Cerebellar Lobule-Specific Electric Field Distribution

OBJECTIVE

Cerebellar transcranial direct current stimulation (ctDCS) is challenging due to the complexity of the cerebellar structure which is reflected by the well-known variability in ctDCS effects. Therefore, our objective is to present a freely available computational modeling pipeline for cerebellar lobules' optimal stimulation (CLOS).

METHODS

CLOS can optimize lobule-specific electric field distribution following finite element analysis (FEA) using freely available computational modeling pipelines. We modeled published ctDCS montages with 5 cm × 5 cm anode placed 3 cm lateral to inion, and the same sized cathode was placed on the: (1) contralateral supra-orbital area (called Manto montage), and (2) buccinators muscle (called Celnik montage). Also, a published (3) 4×1 HD-ctDCS electrode montage was modeled. We also investigated the effects of the subject-specific head model versus Colin 27 average head model on lobule-specific electric field distribution. Three-way analysis of variance (ANOVA) was used to determine the effects of lobules, montage, and head model on the electric field distribution. The differences in lobule-specific electric field distribution across different freely available computational pipelines were also evaluated using subject-specific head model. We also presented an application of our computational pipeline to optimize a ctDCS electrode montage to deliver peak electric field at the cerebellar lobules VII-IX related to ankle function.

RESULTS

Eta-squared effect size after three-way ANOVA for electric field strength was 0.05 for lobule, 0.00 for montage, 0.04 for the head model, 0.01 for lobule∗montage interaction, 0.01 for lobule∗ head model interaction, and 0.00 for montage∗head model interaction. The electric field strength of both the Celnik and the Manto montages affected the lobules Crus I/II, VIIb, VIII, and IX of the targeted cerebellar hemisphere where Manto montage had a spillover to the contralateral cerebellar hemisphere. The 4×1 HD-ctDCS montage primarily affected the lobules Crus I/II of the targeted cerebellar hemisphere. All three published ctDCS montages were found to be not optimal for ankle function (lobules VII-IX), so we presented a novel HD-ctDCS electrode montage.

DISCUSSION

Our freely available CLOS pipeline can be leveraged to optimize electromagnetic stimulation to target cerebellar lobules related to different cognitive and motor functions.

The Curious Case of the Arabic–English Bilingual Speaker with Substantial Rote Rehearsal Practice

The main goal of the present study was to determine whether the probability of correct and illusory recall of word lists varies with participants’ frequency of memorization and recitation practice. The ancillary goal was to determine whether the concurrent presentation of Arabic words and English translations would influence correct and illusory recall rates relative to monolingual presentation. The words in each list were selected to gravitate around a theme word, which was never presented. In this procedure, recall of the theme word was considered prima facie evidence of an illusory memory. Participants were Arabic–English bilingual speakers from the Kingdom of Saudi Arabia (KSA). No effects of bilingual presentation on correct and illusory recall were observed in Experiment 1, which relied on lists developed in the United States for monolingual English speakers, and in Experiment 3, which relied on culturally appropriate lists. However, bilingual presentation reduced generic semantic intrusions in Experiment 1. Participants’ illusory recall rates were lower than those of published norms gathered from English-speaking monolingual participants. In Experiment 1, generic semantic intrusions declined as the breadth of participants’ recitation practice increased. No other significant correlations were found between memory indices and performance or sentiment measures of rote rehearsal. The implications of the finding that a didactic and religious practice taught to KSA students from an early age has little impact on the retention of verbal information are discussed.

Association of intracortical myelin and cognitive function in bipolar I disorder

OBJECTIVE

Although cognitive dysfunction persists through affective and euthymic states in bipolar disorder (BD), its neurobiological correlates remain undetermined. We explore whole-cortex intracortical myelin (ICM) and cognition in BD-I and controls.

METHODS

T₁ -weighted images (3T) optimized for ICM measurement were analyzed using a surface-based approach. MRI signal was sampled at cortical mid-depth. Cognitive performance was measured via standardized computerized battery and paper-and-pencil Trails B.

RESULTS

ICM was associated with verbal memory (VM) in BD throughout a cortical network identified with pertinence to VM function, with strongest effects in left caudal middle temporal cortex and left dorsolateral prefrontal cortex (P_corrected  < 0.05). Subanalyses revealed specific association with correct word recognition, without delay. Processing speed, executive function, and reaction time were also predicted by ICM in BD, but not controls, although this did not survive Bonferroni correction.

CONCLUSION

This is the first study to show VM association with ICM in BD. ICM has been implicated in the integrity of neural connections and neural synchrony. VM dysfunction is one of the most replicated cognitive abnormalities in BD. Therefore, these results provide a novel mechanism for understanding cognitive dysfunction in BD, which can aid in the development of targeted therapeutics to improve cognitive outcomes in BD.

Plasticity in deep and superficial white matter: a DTI study in world class gymnasts

Brain white matter (WM) could be generally categorized into two types, deep and superficial WM. Studies combining these two types WM are important for a better understanding of brain plasticity induced by motor training. In this study, we applied both univariate and multivariate approaches to study gymnastic training-induced plasticity in brain WM. Specifically, we acquired diffusion tensor imaging data from 13 world class gymnasts and 14 non-athlete normal controls, reconstructed brain deep and superficial WM tracts, estimated and compared their fractional anisotropy (FA) difference between the two groups. Taking FA values as the features, we applied logistic regression and support vector machine to distinguish the gymnasts from the controls. Compared to the controls, the gymnasts showed lower FA in four regional deep WM tracts, including the occipital lobe portion of left inferior fronto-occipital fasciculus (IFOF.L), occipital and temporal lobe portion of right inferior longitudinal fasciculus (ILF.R), insular cortex portion of right uncinate fasciculus (UF.R), and parietal lobe portion of right arcuate fasciculus (AF.R). Meanwhile, we found lower FA in the superficial U-shaped tracts within the frontal lobe in the gymnasts compared to the controls. In addition, we detected that mean FA in either the AF.R or the U-shaped tracts connecting the left pars triangularis and superior frontal gyrus was negatively correlated with years of training in the gymnasts. Classification analyses indicated FA in deep WM hold higher potential to distinguish the gymnasts from the controls. Overall, our findings provide a more complete picture of training-induced plasticity in brain WM.

Structural neuroplasticity of the superior temporal plane in early and late blindness

Blindness is associated with well-documented changes to the morphometry and function of the occipital cortex. By comparison, its impact on the perisylvian regions in the superior temporal plane (STP) is poorly understood, with many studies reporting null findings on this issue. Here we re-approach this question using a morphometric analysis that relied on fine-scale, manual annotation of 13 sub-regions within the STP and that quantified both univariate and multivariate differences in morphometry. We applied these analyses to both cortical thickness (CT) and surface area (SA) data from congenitally and late blind, as compared to two matched sighted control groups. The univariate analyses indicated that for CT, no region differentiated blind from sighted, and for SA, two regions showed lower values for congenitally blind. Moreover, the multivariate analyses identified more robust signatures of plasticity in blindness. Specifically, pairwise regional correlations of CT values between contralateral regions were significantly higher for both blind groups as compared to sighted controls. A similar pattern for SA data was found for congenitally blind alone. Our findings indicate that blindness strongly impacts STP, resulting in a more coordinated pattern of interhemispheric morphometric development. We discuss implications for theories of language plasticity and models of neuroplasticity in the blind.

Retrosplenial cortical thinning as a possible major contributor for cognitive impairment in HIV patients

OBJECTIVES

To identify brain cortical regions relevant to HIV-associated neurocognitive disorder (HAND) in HIV patients.

METHODS

HIV patients with HAND (n = 10), those with intact cognition (HIV-IC; n = 12), and age-matched, seronegative controls (n = 11) were recruited. All participants were male and underwent 3-dimensional T1-weighted imaging. Both vertex-wise and region of interest (ROI) analyses were performed to analyse cortical thickness.

RESULTS

Compared to controls, both HIV-IC and HAND showed decreased cortical thickness mainly in the bilateral primary sensorimotor areas, extending to the prefrontal and parietal cortices. When directly comparing HIV-IC and HAND, HAND showed cortical thinning in the left retrosplenial cortex, left dorsolateral prefrontal cortex, left inferior parietal lobule, bilateral superior medial prefrontal cortices, right temporoparietal junction and left hippocampus, and cortical thickening in the left middle occipital cortex. Left retrosplenial cortical thinning showed significant correlation with slower information processing, declined verbal memory and executive function, and impaired fine motor skills.

CONCLUSIONS

This study supports previous research suggesting the selective vulnerability of the primary sensorimotor cortices and associations between cortical thinning in the prefrontal and parietal cortices and cognitive impairment in HIV-infected patients. Furthermore, for the first time, we propose retrosplenial cortical thinning as a possible major contributor to HIV-associated cognitive impairment.

KEY POINTS

• Primary sensorimotor and supplementary motor cortices were selectively vulnerable to HIV infection • Prefrontal and parietal cortical thinning was associated with HIV-associated cognitive impairment • Retrosplenial cortical thinning might be a major contributor to HIV-associated cognitive impairment.

Brain networks for visual creativity: a functional connectivity study of planning a visual artwork

Throughout recorded history, and across cultures, humans have made visual art. In recent years, the neural bases of creativity, including artistic creativity, have become a topic of interest. In this study we investigated the neural bases of the visual creative process with both professional artists and a group of control participants. We tested the idea that creativity (planning an artwork) would influence the functional connectivity between regions involved in the default mode network (DMN), implicated in divergent thinking and generating novel ideas, and the executive control network (EN), implicated in evaluating and selecting ideas. We measured functional connectivity with functional Magnetic Resonance Imaging (fMRI) during three different conditions: rest, visual imagery of the alphabet and planning an artwork to be executed immediately after the scanning session. Consistent with our hypothesis, we found stronger connectivity between areas of the DMN and EN during the creative task, and this difference was enhanced in professional artists. These findings suggest that creativity involves an expert balance of two brain networks typically viewed as being in opposition.

Regional cerebellar volumetric correlates of manual motor and cognitive function

Cerebellar volume declines with aging. Few studies have investigated age differences in regional cerebellar volume (RCV) and their association with motor and cognitive function. In 213 healthy older adults, we investigated the association of age with motor skills, cognition and RCV. Subsequently, we studied the association of RCV with motor skills and cognition. RCVs were derived from T1-weighted MRI scans using the automated SUIT segmentation method and clustered using principal component analysis (PCA). Motor skill (manual dexterity, tapping speed, bimanual visuomotor coordination, grip force) and cognition (mental rotation, verbal memory, inhibition, mental flexibility) were assessed. Behavioral measures were clustered into compounds using PCA: left hand motor skill, right hand motor skill, verbal memory and mental flexibility, and mental rotation & inhibition. Volume of the rostral middle frontal gyri (rMFG) and premotor areas (PMA) were related to performance for reference. Analyses were adjusted for age, sex, and education. Volume of the cerebellar anterior lobe and top of the superior posterior lobe were positively associated with motor skill. Volume of the bottom part of the posterior superior lobe and the inferior posterior lobe was positively associated with cognition. PMA volume was associated with cognition and motor skill and rMFG volume with motor skill. Although these results did not survive FDR correction, their effect sizes suggest that regional cerebellar volume selectively contributes to cognitive and motor skill. Effect sizes of cerebellar associations with performance were similar to those of rMFG/PMA and performance suggesting parallel contributions to performance.