Differences In Brain Morphology Research Articles

A Systematic Review of Structural and Functional Imaging Correlates of Headache or Pain after Mild Traumatic Brain Injury.

Headaches and pain-related symptoms are the most disabling somatic complaints following mild traumatic brain injury (mTBI). In this study, we reviewed the existing literature examining structural differences in brain morphology and axonal connections, as well as functional differences in brain activity and connectivity associated with pain or post-traumatic headache (PTH) following mTBI. We searched MEDLINE®, Embase, PubMed, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials, and Web of Science databases for: (1) TBI OR concussion OR post-concussion syndrome; (2) pain OR headache; and (3) magnetic resonance imaging OR functional MRI OR diffusion tensor imaging. Inclusion criteria were that articles be original studies written in English about participants with mTBI or concussion diagnosis with results reported about pain and/or headache. Excluded were review articles, case studies, documentaries, and studies related to moderate to severe TBI. Quality was assessed using the Newcastle-Ottawa Scale (NOS) quality assessment tool. Nineteen out of 3439 studies satisfied the inclusion and exclusion criteria. Participants with pain-related symptoms had lower cortical thickness in frontal and parietal cortical areas and spinothalamic tract volume. Differences in axonal connectivity were displayed in the corpus callosum, spinothalamic tract, fornix-septohippocampal circuit, and periaqueductal gray. Less activation in pain-related regions during a heat-pain task-based fMRI was reported in participants with PTH. In conclusion, individuals with pain following mTBI display differences in brain structure and brain function, suggesting irregularities in the descending pain modulatory system. These findings primarily provide information on neuroimaging differences in adults; there is limited research in pediatric populations.

BRAHMA: Population specific T1, T2, and FLAIR weighted brain templates and their impact in structural and functional imaging studies

Differences in brain morphology across population groups necessitate creation of population-specific Magnetic Resonance Imaging (MRI) brain templates for interpretation of neuroimaging data. Variations in the neuroanatomy in a genetically heterogeneous population make the development of a population-specific brain template for the Indian subcontinent imperative. A dataset of high-resolution 3D T1, T2-weighted, and FLAIR images acquired from a group of 113 volunteers (M/F - 56/57, mean age-28.96 ± 7.80 years) are used to construct T1, T2-weighted, and FLAIR templates, collectively referred to as Indian Brain Template, “BRAHMA”. A processing pipeline is developed and implemented in a MATLAB based toolbox for template construction and generation of tissue probability maps and segmentation atlases, with additional labels for deep brain regions such as the Substantia Nigra generated from the T2-weighted and FLAIR templates. The use of BRAHMA template for analysis of structural and functional neuroimaging data obtained from Indian participants, provides improved accuracy with statistically significant results over that obtained using the ICBM-152 (International Consortium for Brain Mapping) template. Our results indicate that segmentations generated on structural images are closer in volume to those obtained from registration to the BRAHMA template than to the ICBM-152. Furthermore, functional MRI data obtained for Working Memory and Finger Tapping paradigms processed using the BRAHMA template show a significantly higher percentage of the activation area than ICBM-152 in relevant brain regions, i.e. the left middle frontal gyrus, and the left and right precentral gyri, respectively. The availability of different image contrasts, tissue maps, and segmentation atlases makes the BRAHMA template a comprehensive tool for multi-modal image analysis in laboratory and clinical settings.

Neurocognitive markers of childhood abuse in individuals with PTSD: Findings from the INTRuST Clinical Consortium

To date, few studies have evaluated the contribution of early life experiences to neurocognitive abnormalities observed in posttraumatic stress disorder (PTSD). Childhood maltreatment is common among individuals with PTSD and is thought to catalyze stress-related biobehavioral changes that might impact both brain structure and function in adulthood. The current study examined differences in brain morphology (brain volume, cortical thickness) and neuropsychological performance in individuals with PTSD characterized by low or high self-reported childhood maltreatment, compared with healthy comparison participants. Data were drawn from the INjury and TRaUmatic STress (INTRuST) Clinical Consortium imaging repository, which contains MRI and self-report data for individuals classified as PTSD positive (with and without a history of mild traumatic brain injury [mTBI]), individuals with mTBI only, and healthy comparison participants. The final sample included 36 individuals with PTSD without childhood maltreatment exposure (PTSD, n = 30 with mTBI), 31 individuals with PTSD and childhood maltreatment exposure (PTSD + M, n = 26 with mTBI), and 114 healthy comparison participants without history of childhood maltreatment exposure (HC). The PTSD + M and PTSD groups demonstrated cortical thinning in prefrontal and occipital regions, and poorer verbal memory and processing speed compared to the HC group. PTSD + M participants demonstrated cortical thinning in frontal and cingulate regions, and poorer executive functioning relative to the PTSD and HC groups. Thus, neurocognitive features varied between individuals with PTSD who did versus did not have exposure to childhood maltreatment, highlighting the need to assess developmental history of maltreatment when examining biomarkers in PTSD.

Opioid Use in Pregnancy.

Perinatal opioid use is a major public health problem and is associated with a number of deleterious maternal and fetal effects. We review recent evidence of perinatal outcomes and treatment of opioid use disorder (OUD) during pregnancy. Opioid exposure in pregnancy is associated with multiple obstetric and neonatal adverse outcomes, with the most common being neonatal opioid withdrawal syndrome (NOWS). Treatment with buprenorphine or methadone is associated with NOWS, but neither medication appears to have significant adverse effects on early childhood development. Buprenorphine appears to be superior to methadone in terms of incidence and severity of NOWS in exposed infants. The long-term effects of opioid exposure in utero have been inconclusive, but recent longitudinal studies point to potential differences in brain morphology that may increase vulnerability to future stressors. Maintenance therapy with methadone or buprenorphine remains the standard of care for pregnant women with OUD given its consistent superiority to placebo in terms of rates of illicit drug use and pregnancy outcomes. New non-pharmacologic management options for NOWS appear promising. Future research is needed to further evaluate the effects of opioid exposure in utero and determine the optimal delivery model for maintenance therapy.

Observed infant-parent attachment and brain morphology in middle childhood– A population-based study

Poor quality of the early infant-parent bond predicts later child problems. Infant-parent attachment has been suggested to influence brain development, but this association has hardly been examined. In adults, larger amygdala volumes have been described in relation to early attachment disorganization; neuroimaging studies of attachment in children, however, are lacking.We examined the association between infant-parent attachment and brain morphology in 551 children from a population-based cohort in the Netherlands. Infant-parent attachment was observed with the Strange-Situation Procedure at age 14 months and different brain measures were collected with magnetic resonance imaging at mean age 10 years.Children with disorganized infant attachment had larger hippocampal volumes than those with organized attachment patterns. This finding was robust to the adjustment for confounders and consistent across hemispheres. The association was not explained by cognitive or emotional and behavioral problems. Disorganized attachment did not predict any other difference in brain morphology. Moreover, children with insecure organized infant attachment patterns did not differ from those who were securely attached in any brain outcome.Causality cannot be inferred, but our findings in this large population-based study provide novel evidence for a long-term association between the quality of infant-parent attachment and specific brain differences in childhood.

In vivo magnetic resonance imaging reveals the effect of gonadal hormones on morphological and functional brain sexual dimorphisms in adult sheep

Sex differences in the brain and behavior are produced by the perinatal action of testosterone, which is converted into estradiol by the enzyme aromatase in the brain. Although magnetic resonance imaging (MRI) has been widely used in humans to study these differences, the use of animal models, where hormonal status can be properly manipulated, is necessary to explore the mechanisms involved. We used sheep, a recognized model in the field of neuroendocrinology, to assess brain morphological and functional sex differences and their regulation by adult gonadal hormones. To this end, we performed voxel-based morphometry and a resting-state functional MRI approach to assess sex differences in gonadally intact animals. We demonstrated significant sex differences in gray matter concentration (GMC) at the level of the gonadotropic axis, i.e., not only within the hypothalamus and pituitary but also within the hippocampus and the amygdala of intact animals. We then performed the same analysis one month after gonadectomy and found that some of these differences were reduced, especially in the hypothalamus and amygdala. By contrast, we found few differences in the organization of the functional connectome between males and females either before or after gonadectomy. As a whole, our study identifies brain regions that are sexually dimorphic in the sheep brain at the resolution of the MRI and highlights the role of gonadal hormones in the maintenance of these differences.

Error processing in the adolescent brain: Age-related differences in electrophysiology, behavioral adaptation, and brain morphology

Detecting errors and adjusting behaviour appropriately are fundamental cognitive abilities that are known to improve through adolescence. The cognitive and neural processes underlying this development, however, are still poorly understood. To address this knowledge gap, we performed a thorough investigation of error processing in a Flanker task in a cross-sectional sample of participants 8 to 19 years of age (n = 98). We examined age-related differences in event-related potentials known to be associated with error processing, namely the error-related negativity (ERN) and the error positivity (Pe), as well as their relationships with task performance, post-error adjustments and regional cingulate cortex thickness and surface area. We found that ERN amplitude increased with age, while Pe amplitude remained constant. A more negative ERN was associated with higher task accuracy and faster reaction times, while a more positive Pe was associated with higher accuracy, independently of age. When estimating post-error adjustments from trials following both incongruent and congruent trials, post-error slowing and post-error improvement in accuracy both increased with age, but this was only found for post-error slowing when analysing trials following incongruent trials. There were no age-independent associations between either ERN or Pe amplitude and cingulate cortex thickness or area measures.

Are There Differences in Brain Morphology in Patients with Lifelong Premature Ejaculation?

IntroductionEven though lifelong premature ejaculation (PE) is highly prevalent, few studies have investigated the neural mechanisms underlying PE. AimThis study aimed to investigate whether patients with lifelong PE exhibit macrostructural or microstructural alterations of the parts of the brain involved in the male sexual response. Materials and MethodsWe enrolled 42 healthy participants and 54 lifelong PE patients. Lifelong PE was diagnosed according to the Premature Ejaculation Diagnostic Tool (PEDT) and intravaginal ejaculation latency time (IELT). We compared measures of cortical morphology, such as volumes of gray matter, white matter, cerebellum volumes, and subcortical structures (ie, amygdala, caudate, hippocampus, globus pallidus, putamen, and thalamus) between the groups using a voxel-based morphometry method from whole-brain T1-weighted magnetic resonance imaging. Moreover, we evaluated the relationships between the relevant cerebral alterations and the severity of symptoms obtained from participants via self-reported questionnaires. Main Outcome MeasuresCerebral macrostructural and microstructural alterations were assessed in PE patients and controls, along with the correlation of caudate nucleus changes in PE patients with clinical data (including the PEDT and the IELT). ResultsThe mean volume of the caudate nucleus was significantly larger in the lifelong PE patients compared with healthy controls (P = .048). Moreover, caudate nucleus volume was positively correlated with PEDT score (r = 0.621; P = .0179) and negatively correlated with the IELT (r = −0.592; P = .0101). However, cortex morphology and the other subcortical volumes were not significantly different between the 2 groups (P > .05). Clinical ImplicationsMicrostructural alterations in deep gray matter nuclei might be a useful parameter for studying the mechanism of the neurobiology underlying PE. Strengths and LimitationsThere are few studies examining microstructural changes in PE patients. This study furthers our understanding of the etiology of PE. Limitations include the small sample, which limits our ability to make an absolute determination as to whether such subcortical changes are the cause or the consequence of lifelong PE. ConclusionsWe found a significant difference in caudate nucleus volume between patients with PE and healthy controls. In addition, the caudate nucleus volume was positively associated with the severity of PE symptoms. More extensive and possibly longitudinal studies are needed to improve our understanding of the mechanism of the neurobiology underlying PE.Atalay HA, Sonkaya AR, Ozbir S, et al. Are There Differences in Brain Morphology in Patients with Lifelong Premature Ejaculation? J Sex Med 2019;16:992–998.

Structural brain characteristics of anabolic-androgenic steroid dependence in men.

AimTo identify differences in brain morphology between dependent and non‐dependent male anabolic–androgenic steroid (AAS) users.DesignThis study used cross‐sectional data from a longitudinal study on male weightlifters.ParticipantsOslo University Hospital, Norway.SettingEighty‐one AAS users were divided into two groups; AAS‐dependent (n = 43) and AAS‐non‐dependent (n = 38).MeasurementsNeuroanatomical volumes and cerebral cortical thickness were estimated based on magnetic resonance imaging (MRI) using FreeSurfer. Background and health information were obtained using a semi‐structured interview. AAS‐dependence was evaluated in a standardized clinical interview using a version of the Structured Clinical Interview for DSM‐IV, adapted to apply to AAS‐dependence.FindingsCompared with non‐dependent users, dependent users had significantly thinner cortex in three clusters of the right hemisphere and in five clusters of the left hemisphere, including frontal, temporal, parietal and occipital regions. Profound differences were seen in frontal regions (left pars orbitalis, cluster‐wise P < 0.001, right superior frontal, cluster‐wise P < 0.001), as has been observed in other dependencies. Group differences were also seen when excluding participants with previous or current non‐AAS drug abuse (left pre‐central, cluster‐wise P < 0.001, left pars orbitalis, cluster‐wise P = 0.010).ConclusionMale dependent anabolic–androgenic steroid users appear to have thinner cortex in widespread regions, specifically in pre‐frontal areas involved in inhibitory control and emotional regulation, compared with non‐dependent anabolic–androgenic steroid users.

Age-Related Differences in Brain Morphology and the Modifiers in Middle-Aged and Older Adults.

Brain structural morphology differs with age. This study examined age-differences in surface-based morphometric measures of cortical thickness, volume, and surface area in a well-defined sample of 8137 generally healthy UK Biobank participants aged 45-79 years. We illustrate that the complexity of age-related brain morphological differences may be related to the laminar organization and regional evolutionary history of the cortex, and age of about 60 is a break point for increasing negative associations between age and brain morphology in Alzheimer's disease (AD)-prone areas. We also report novel relationships of age-related cortical differences with individual factors of sex, cognitive functions of fluid intelligence, reaction time and prospective memory, cigarette smoking, alcohol consumption, sleep disruption, genetic markers of apolipoprotein E, brain-derived neurotrophic factor, catechol-O-methyltransferase, and several genome-wide association study loci for AD and further reveal joint effects of cognitive functions, lifestyle behaviors, and education on age-related cortical differences. These findings provide one of the most extensive characterizations of age associations with major brain morphological measures and improve our understanding of normal structural brain aging and its potential modifiers.

Brain Morphology in Patients with Genetic Generalized Epilepsy: Its Heterogeneity among Subsyndromes

Background: We aimed to evaluate the brain morphology of patients with genetic generalized epilepsy (GGE) compared to healthy subjects. In addition, we investigated whether there are differences in brain morphology among different GGE syndromes. Methods: We enrolled 100 patients with a clinical diagnosis of GGE. The patients were classified into different syndrome groups according to their predominant seizure type, age of seizure onset, and electroencephalography characteristics (12 childhood absence epilepsy [AE], 13 juvenile AE, 56 juvenile myoclonic epilepsy, and 19 epilepsy with generalized tonic-clonic alone). We used surface-based morphometry of brain magnetic resonance imaging to evaluate brain morphology. Results: We found significantly widespread alterations of brain morphology, including cortical thickness and volumes in several regions in the patients with GGE compared to healthy controls. In addition, we observed significant differences in alterations of cortical thickness and volumes among the different GGE syndromes. However, there were no differences in cortical surface areas between the patients with GGE and healthy controls. There was a significantly negative correlation between the duration of epilepsy and most of the each measures of abnormal brain morphology. Conclusions: The main finding of this study is that brain morphology in patients with GGE is significantly different from that in healthy controls. In addition, we found that the different GGE syndromes show distinct structural brain morphology, especially cortical thickness, which can help us understand the pathogenesis of GGE syndromes.

Construction of Indian human brain atlas.

A brain magnetic resonanace imaging (MRI) atlas plays an important role in many neuroimage analysis tasks as it provides an atlas with a standard coordinate system which is needed for spatial normalization of a brain MRI. Ideally, this atlas should be as near to the average brain of the population being studied as possible. The aim of this study is to construct and validate the Indian brain MRI atlas of young Indian population and the corresponding structure probability maps. This was a population-specific atlas generation and validation process. 100 young healthy adults (M/F = 50/50), aged 21-30 years, were recruited for the study. Three different 1.5-T scanners were used for image acquisition. The atlas and structure maps were created using nonrigid groupwise registration and label-transfer techniques. The generated atlas was compared against other atlases to study the population-specific trends. The atlas-based comparison indicated a signifi cant difference between the global size of Indian and Caucasian brains. This difference was noteworthy for all three global measures, namely, length, width, and height. Such a comparison with the Chinese and Korean brain templates indicate all 3 to be comparable in length but signifi cantly different (smaller) in terms of height and width. The findings confirm that there is significant difference in brain morphology between Indian, Chinese, and Caucasian populations.

Sex Differences Along the Autism Continuum: A Twin Study of Brain Structure.

Females might possess protective mechanisms regarding autism spectrum disorder (ASD) and require a higher detrimental load, including structural brain alterations, before developing clinically relevant levels of autistic traits. This study examines sex differences in structural brain morphology in autism and autistic traits using a within-twin pair approach. Twin design inherently controls for shared confounders and enables the study of gene-independent neuroanatomical variation. N = 148 twins (62 females) from 49 monozygotic and 25 dizygotic same-sex pairs were included. Participants were distributed along the whole continuum of autism including twin pairs discordant and concordant for clinical ASD. Regional brain volume, surface area, and cortical thickness were computed. Within-twin pair increases in autistic traits were related to decreases in cortical volume and surface area of temporal and frontal regions specifically in female twin pairs, in particular regions involved in social communication, while only two regions were associated with autistic traits in males. The same pattern was detected in the monozygotic twin pairs only. Thus, non-shared environmental factors seem to impact female more than male cerebral architecture associated with autistic traits. Our results are in line with the hypothesis of a female protective effect in autism and highlights the need to study ASD in females separately from males.

Blood-based bioenergetic profiling is related to differences in brain morphology in African Americans with Type 2 diabetes.

Blood-based bioenergetic profiling has promising applications as a minimally invasive biomarker of systemic bioenergetic capacity. In this study, we examined peripheral blood mononuclear cell (PBMC) mitochondrial function and brain morphology in a cohort of African Americans with longstanding Type 2 diabetes. Key parameters of PBMC respiration were correlated with white matter, gray matter, and total intracranial volumes. Our analyses indicate that these relationships are primarily driven by the relationship of systemic bioenergetic capacity with total intracranial volume, suggesting that systemic differences in mitochondrial function may play a role in overall brain morphology.

Fitness, cortical thickness and surface area in overweight/obese children: The mediating role of body composition and relationship with intelligence

Cortical thickness and surface area are thought to be genetically unrelated and shaped by independent neurobiological events suggesting that they should be considered separately in morphometric analyses. Although the developmental trajectories of cortical thickness and surface area may differ across brain regions and ages, there is no consensus regarding the relationships of physical fitness with cortical thickness and surface area as well as for its subsequent influence on intelligence. Thus, this study examines: (i) the associations of physical fitness components (i.e., cardiorespiratory fitness, speed-agility and muscular fitness) with overall and regional cortical thickness and surface area; (ii) whether body composition indicators (i.e., body mass index, fat-free mass index and fat mass index) mediate these associations; and (iii) the association of physical fitness and cortical thickness with intelligence in overweight/obese children. A total of 101 overweight/obese children aged 8–11 years were recruited in Granada, Spain. The physical fitness components were assessed following the ALPHA health-related fitness test battery. T1-weighted images were acquired with a 3.0 Tesla Siemens Magnetom Tim Trio system. We used FreeSurfer software version 5.3.0 to assess cortical thickness (mm) and surface area (mm2). The main results showed that cardiorespiratory fitness and speed-agility were related to overall cortical thickness (β = 0.321 and β = 0.302, respectively; both P < 0.05), and in turn, cortical thickness was associated with higher intelligence (β = 0.198, P < 0.05). Muscular fitness was not related to overall cortical thickness. None of the three physical fitness components were related to surface area (p > 0.05). The associations of cardiorespiratory fitness and speed-agility with overall cortical thickness were mediated by fat mass index (56.86% & 62.28%, respectively). In conclusion, cardiorespiratory fitness and speed-agility, but not muscular fitness, are associated with overall cortical thickness, and in turn, thicker brain cortex is associated with higher intelligence in overweight/obese children. Yet, none of the three physical fitness components were related to surface area. Importantly, adiposity may hinder the benefits of cardiorespiratory fitness and speed-agility on cortical thickness. Understanding individual differences in brain morphology may have important implications for educators and policy makers who aim to determine policies and interventions to maximize academic learning and occupational success later in life.

The peripheral nerves of Lepidobatrachus tadpoles (Anura, Ceratophryidae)

The peripheral nervous system of anuran larvae has traditionally been assumed to be largely invariant. Here, we describe the organization of cranial, spinal, and lateral line nerves at different larval stages of Lepidobatrachus spp. based on whole mounts. This is the first detailed description of cranial, spinal, and lateral lines innervation at premetamorphic stages of anuran larvae with notes on temporal variation. We distinguish three sources of morphological variation with respect to other anuran larvae: (a) the loss or reduction of some exclusively larval elements (i.e., the absence of the middle lateral line nerve); (b) spatial changes in the lateral line system (i.e., the supralabial arrangement of component of the anteroventral lateral line nerve); and (c) temporal changes in the disappearance of most of the lateral line system and in the premetamorphic repatterning of the spatial relationships of mandibularis ramus of the trigeminal (V) and hyomandibularis ramus of facial (VII). The innervation of limbs is achieved during late larval stages. Furthermore, comparisons among selected anurans reveal differences in tadpole brain morphology. The spatial and temporal variation found in the peripheral nerves of Lepidobatrachus larvae testifies to previously unappreciated variation in anuran larval morphology.

Tensor-based morphometry using scalar and directional information of diffusion tensor MRI data (DTBM): Application to hereditary spastic paraplegia.

Tensor-based morphometry (TBM) performed using T1-weighted images (T1WIs) is a well-established method for analyzing local morphological changes occurring in the brain due to normal aging and disease. However, in white matter regions that appear homogeneous on T1WIs, T1W-TBM may be inadequate for detecting changes that affect specific pathways. In these regions, diffusion tensor MRI (DTI) can identify white matter pathways on the basis of their different anisotropy and orientation. In this study, we propose performing TBM using deformation fields constructed using all scalar and directional information provided by the diffusion tensor (DTBM) with the goal of increasing sensitivity in detecting morphological abnormalities of specific white matter pathways. Previously, mostly fractional anisotropy (FA) has been used to drive registration in diffusion MRI-based TBM (FA-TBM). However, FA does not have the directional information that the tensors contain, therefore, the registration based on tensors provides better alignment of brain structures and better localization of volume change. We compare our DTBM method to both T1W-TBM and FA-TBM in investigating differences in brain morphology between patients with complicated hereditary spastic paraplegia of type 11 (SPG11) and a group of healthy controls. Effect size maps of T1W-TBM of SPG11 patients showed diffuse atrophy of white matter. However, DTBM indicated that atrophy was more localized, predominantly affecting several long-range pathways. The results of our study suggest that DTBM could be a powerful tool for detecting morphological changes of specific white matter pathways in normal brain development and aging, as well as in degenerative disorders.

Cortical Thickness Alterations in Chronic Pain Disorder: An Exploratory MRI Study.

Chronic pain disorder (CPD) has been associated with brain changes, especially in limbic circuits. However, in most patients with chronic pain, depression or anxiety is a common comorbidity. In this exploratory and naturalistic study, we investigated brain cortical thickness (CTh) differences between patients with CPD and healthy controls, with consideration of concurrent psychiatric symptoms. Twenty-three patients with CPD and 23 age- and sex-matched healthy volunteers were included in this study. CTh was estimated using Freesurfer on high-resolution three-dimensional T1-weighted images acquired with a 3T scanner. Group differences were investigated using an analysis of covariance model that included age, sex, and Beck Depression Inventory I and Trait Anxiety Inventory scores as covariates. The relationship between CTh and Toronto Alexithymia Scale (TAS-20) scores was also investigated in patients. Data were corrected for multiplicity using the False Discovery Rate approach (q < .05). The comparison between groups using demographics and Beck Depression Inventory I scores as covariates showed thinner cortex in patients compared with controls, after correction for multiplicity in the left precentral (F(1,42) = 21.9, p < .05) and postcentral gyri (F(1,42) = 26.9, p < .05) and in the left inferior temporal sulcus (F(1,42) = 19.6, p < .05). Moreover, using the Trait Anxiety Inventory as covariate, a trend toward significance (p < .001 uncorrected) was seen for the left precentral gyrus (F(1,42) = 13.8), right middle frontal (F(1,42) = 14.3) and inferior parietal gyri (F(1,42) = 13.4), and right anterior temporal pole (F(1,42) = 15.9). The results indicate that brain morphological differences between patients with chronic pain disorder and healthy controls are localized to regions that correspond to sensory as well as affective dimensions of pain processing.

Neuroanatomy of Shared Conversational Laughter in Neurodegenerative Disease.

Perceiving another person's emotional expression often sparks a corresponding signal in the observer. Shared conversational laughter is a familiar example. Prior studies of shared laughter have made use of task-based functional neuroimaging. While these methods offer insight in a controlled setting, the ecological validity of such controlled tasks has limitations. Here, we investigate the neural correlates of shared laughter in patients with one of a variety of neurodegenerative disease syndromes (N = 75), including Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), right and left temporal variants of semantic dementia (rtvFTD, svPPA), nonfluent/agrammatic primary progressive aphasia (nfvPPA), corticobasal syndrome (CBS), and progressive supranuclear palsy (PSP). Patients were recorded in a brief unrehearsed conversation with a partner (e.g., a friend or family member). Laughter was manually labeled, and an automated system was used to assess the timing of that laughter relative to the partner's laughter. The probability of each participant with neurodegenerative disease laughing during or shortly after his or her partners' laughter was compared to differences in brain morphology using voxel-based morphometry, thresholded based on cluster size and a permutation method and including age, sex, magnet strength, disease-specific atrophy and total intracranial volumes as covariates. While no significant correlations were found at the critical T value, at a corrected voxelwise threshold of p < 0.005, a cluster in the left posterior cingulate gyrus demonstrated a trend at p = 0.08 (T = 4.54). Exploratory analysis with a voxelwise threshold of p = 0.001 also suggests involvement of the left precuneus (T = 3.91) and right fusiform gyrus (T = 3.86). The precuneus has been previously implicated in the detection of socially complex laughter, and the fusiform gyrus has a well-described role in the recognition and processing of others' emotional cues. This study is limited by a relatively small sample size given the number of covariates. While further investigation is needed, these results support our understanding of the neural underpinnings of shared conversational laughter.

Testing associations between cannabis use and subcortical volumes in two large population-based samples.

Disentangling the putative impact of cannabis on brain morphology from other comorbid substance use is critical. After controlling for the effects of nicotine, alcohol and multi-substance use, this study aimed to determine whether frequent cannabis use is associated with significantly smaller subcortical grey matter volumes. Exploratory analyses using mixed linear models, one per region of interest (ROI), were performed whereby individual differences in volume (outcome) at seven subcortical ROIs were regressed onto cannabis and comorbid substance use (predictors). Two large population-based twin samples from the United States and Australia. A total of 622 young Australian adults [66% female; μage =25.9, standard deviation SD)=3.6] and 474 middle-aged US males (μage =56.1SD=2.6 ) of predominately Anglo-Saxon ancestry with complete substance use and imaging data. Subjects with a history of stroke or traumatic brain injury were excluded. Magnetic resonance imaging (MRI) and volumetric segmentation methods were used to estimate volume in seven subcortical ROIs: thalamus, caudate nucleus, putamen, pallidum, hippocampus, amygdala and nucleus accumbens. Substance use measurements included maximum nicotine and alcohol use, total life-time multi-substance use, maximum cannabis use in the young adults and regular cannabis use in the middle-aged males. After correcting for multiple testing (P=0.007), cannabis use was unrelated to any subcortical ROI. However, maximum nicotine use was associated with significantly smaller thalamus volumes in middle-aged males. In exploratory analyses based on young adult and middle-aged samples, normal variation in cannabis use is unrelated statistically to individual differences in brain morphology as measured by subcortical volume.