Large Brain Research Articles

Abstract MP25: Brain Atrophy And White Matter Injury In Relation To Cardiovascular Risk Factors And Race/ethnicity: The Multi-ethnic Study Of Atherosclerosis

Introduction: Cardiovascular risk factors are associated with cognitive decline and dementia. Brain magnetic resonance imaging (MRI) provides sensitive measurement of cerebral atrophy and small vessel disease, reflecting multiple pathologies leading to dementia. However, large brain MRI studies include primarily white participants. We investigated associations in the diverse Multi-Ethnic Study of Atherosclerosis (MESA). Hypothesis: Cardiovascular and sociodemographic risk factors are associated with brain morphology and white matter injury in a racially and ethnically diverse population. Methods: In MESA, brain MRI was performed in 2018-2019 with automated measurement of total brain volume, gray and white matter (GM, WM) volume, and measures of WM injury including WM lesion volume, WM fractional anisotropy, and WM apparent diffusion coefficient. In cross-sectional analyses, we assessed the association of race/ethnicity with MRI measures, with and without adjustment for cardiovascular risk factors, education, and socioeconomic status. In a multivariable model, we assessed the association of cardiovascular risk factors with brain MRI measures. All analyses of volumes, including WM lesion volume, were adjusted for total intracranial volume. Results: MRI data were complete in 1,051 participants; 40% were white, 15% Chinese-American, 25% African-American, and 20% Hispanic. Mean (standard deviation, SD) age was 73 (8) years and 53% of participants were women. Adjusted for age and sex, African-American participants had slightly greater total brain and WM volume than white participants. Adjusted for age and sex, African-American participants had on average more WM injury than whites as measured by higher WM lesion volume (46.7% higher, 95% CI: 19.9, 79.4%) and lower fractional anisotropy (-0.20 SD, 95% CI: -0.34, -0.05); these associations were attenuated after additional adjustment for cardiovascular risk factors and socioeconomic status (24.3% higher WM lesion volume, 95% CI: 0.0, 54.3; -0.06 SD fractional anisotropy, 95% CI: -0.22, 0.09). Conversely, all non-white race/ethnic groups had slightly less WM injury than white participants as estimated by apparent diffusion coefficient. Overall, greater age, diabetes, current smoking, high systolic blood pressure, and treated hypertension were strongly associated with more WM injury; in addition, age and diabetes were strongly associated with lower brain volumes. Conclusions: We found little evidence of differences in measures of brain atrophy and WM injury by race/ethnicity after adjustment for cardiovascular risk factors and socioeconomic status. Findings of differences by race/ethnicity in apparent diffusion coefficient are intriguing and need further investigation. Consistent with previous studies, age, diabetes, current smoking and hypertension were strongly and consistently associated with WM injury.

Effect of High Frequency Transcranial Magnetic Stimulation on Recovery of Chronic Post-Stroke Aphasia

BackgroundBoth hemispheres have role in post-stroke aphasia recovery but better recovery is expected with the restoration of function by the left hemisphere. Transcranial stimulation has been used to favor recruitment of left-hemispheric language networks and increase activity of the left hemisphere, thus helps aphasia recovery . ObjectiveThe aim of this study is to evaluate the effect of excitatory repetitive transcranial magnetic stimulation (rTMS) on recovery of post stroke aphasic patients . Materials and methodsTwenty patients with post stroke chronic aphasia were enrolled in the study. Aphasia severity was assessed using Aphasia Severity Rating Scale (ASRS). Linguistic deficits were assessed using Kasr Al-Aini Arabic Aphasia test (KAAT). Real rTMS was applied three for 10 sessions of 10-Hz stimulation, positioned over the left Broca's area of the affected hemisphere. All patients were evaluated before, after the end of treatment sessions and one month later . ResultsThere was a significant improvement in the mean total score and mean scores of components of KAAT scale before, immediately after and after one month of rTMS (P< 0.05). Moreover, there was a significant improvement in mean scores of ASRS before, immediately after and after one month of rTMS (P= 0.000). There was a significant difference in mean scores of ASRS and KAAT before, immediately after the last session and after one month between small, medium and large brain infarcts. (P< 0.05). ConclusionExcitatory rTMS is a beneficial adjuvant therapy that improves language skills in patients with chronic post-stroke non-fluent aphasia in short and long term.The protocol of this observational study was registered in clinical trial registration: www.ClinicalTrials.gov, identifier: NCT04708197

Brain size evolution in small mammals: test of the expensive tissue hypothesis

Abstract Brain size exhibits significant changes within and between species. Evolution of large brains can be explained by the need to improve cognitive ability for processing more information in changing environments. However, brains are among the most energetically expensive organs. Enlarged brains can impose energetic demands that limit brain size evolution. The expensive tissue hypothesis (ETH) states that a decrease in the size of another expensive tissue, such as the gut, should compensate for the cost of a large brain. We studied the interplay between energetic limitations and brain size evolution in small mammals using phylogenetically generalized least squares (PGLS) regression analysis. Brain mass was not correlated with the length of the digestive tract in 37 species of small mammals after correcting for phylogenetic relationships and body size effects. We further found that the evolution of a large brain was not accompanied by a decrease in male reproductive investments into testes mass and in female reproductive investment into offspring number. The evolution of brain size in small mammals is inconsistent with the prediction of the ETH.

Prevalence, Severity, and Clinical Management of Brain Incidental Findings in Healthy Young Adults: MRi-Share Cross-Sectional Study.

Background and Objectives: Young adults represent an increasingly large proportion of healthy volunteers in brain imaging research, but descriptions of incidental findings (IFs) in this age group are scarce. We aimed to assess the prevalence and severity of IFs on brain MRIs of healthy young research participants aged 18–35 years, and to describe the protocol implemented to handle them.Methods: The study population comprised 1,867 participants aged 22.1 ± 2.3 years (72% women) from MRi-Share, the cross-sectional brain MRI substudy of the i-Share student cohort. IFs were flagged during the MRI quality control. We estimated the proportion of participants with IFs [any, requiring medical referral, potentially serious (PSIFs) as defined in the UK biobank]: overall, by type and severity of the final diagnosis, as well as the number of IFs.Results: 78/1,867 participants had at least one IF [4.2%, 95% Confidence Interval (CI) 3.4–5.2%]. IFs requiring medical referral (n = 38) were observed in 36/1,867 participants (1.9%, 1.4–2.7%), and represented 47.5% of the 80 IFs initially flagged. Referred IFs were retrospectively classified as PSIFs in 25/1,867 participants (1.3%, 0.9–2.0%), accounting for 68.4% of anomalies referred (26/38). The most common final diagnosis was cysts or ventricular abnormalities in all participants (9/1,867; 0.5%, 0.2–0.9%) and in those with referred IFs (9/36; 25.0%, 13.6–41.3%), while it was multiple sclerosis or radiologically isolated syndrome in participants with PSIFs (5/19; 26.3%, 11.5–49.1%) who represented 0.1% (0.0–0.4%) and 0.2% (0.03–0.5%) of all participants, respectively. Final diagnoses were considered serious in 11/1,867 participants (0.6%, 0.3–1.1%). Among participants with referred IFs, 13.9% (5/36) required active intervention, while 50.0% (18/36) were put on clinical surveillance.Conclusions: In a large brain imaging study of young healthy adults participating in research we observed a non-negligible frequency of IFs. The etiological pattern differed from what has been described in older adults.

Testing the extreme male brain hypothesis: Is autism spectrum disorder associated with a more male-typical brain?

Autism spectrum disorder (ASD) is more common in males than females and has been linked to male-typical behavior. Accordingly, the "Extreme Male Brain" hypothesis suggests that ASD is associated with an exaggeratedly male-typical brain. To test this hypothesis, we derived a data-driven measure of individual differences along a male-female dimension based on sex differences in subcortical brain shape (i.e., brain maleness) by training our algorithm on two population samples (Queensland Twin IMaging study and Human Connectome Project; combined N=2153). We then applied this algorithm to two clinical datasets (Autism Brain Imaging Data Exchange I and II; ASD N=1060; neurotypical controls N=1166) to obtain a brain maleness score for each individual, representing maleness of their brain on a male-female continuum. Consistent with the Extreme Male Brain hypothesis, we found a higher mean brain maleness score in the ASD group than in controls (d=0.20 [0.12-0.29]), parallel to higher scores for control males than control females (d=1.17 [1.05-1.29]). Further, brain maleness was positively associated with autistic symptoms. We tested the possibility this finding was driven by the ASD group's larger brains than controls (d=0.17 [0.08-0.25]), given that males had larger brains than females (d=0.96 [0.84-1.07]). Indeed, after adjusting for differences in brain size, the brain maleness difference between the ASD group and controls disappeared, and no association with autistic symptoms remained (after controlling for multiple comparisons), suggesting greater maleness of the autistic brain is driven by brain size. Brain maleness may be influenced by the same factors that influence brain size. LAY SUMMARY: A popular theory proposes that individuals with autistic spectrum disorder (ASD) have an "extreme male brain", but this has not been subject to rigorous, direct tests. We developed a measure of individual differences along a male-female dimension and then derived this measure for 1060 individuals with ASD and 1166 neurotypical controls. Individuals with ASD had slightly more male-type brains. However, this difference is accounted for by males and individuals with ASD having relatively larger brains than females and controls, respectively.

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.

Brain size evolution in whales and dolphins: new data from fossil mysticetes

Abstract Cetaceans (whales and dolphins) have some of the largest and most complex brains in the animal kingdom. When and why this trait evolved remains controversial, with proposed drivers ranging from echolocation to foraging complexity and high-level sociality. This uncertainty partially reflects a lack of data on extinct baleen whales (mysticetes), which has obscured deep-time patterns of brain size evolution in non-echolocating cetaceans. Building on new measurements from mysticete fossils, we show that the evolution of large brains preceded that of echolocation, and subsequently followed a complex trajectory involving several independent increases (e.g. in rorquals and oceanic dolphins) and decreases (e.g. in right whales and ‘river dolphins’). Echolocating whales show a greater tendency towards large brain size, thus reaffirming cognitive demands associated with sound processing as a plausible driver of cetacean encephalization. Nevertheless, our results suggest that other factors such as sociality were also important.

Staged radiosurgery in the managment of patients with brain metastases

The study objective is to present the results of the treatment of metastatic brain patients by the staged radiosurgery with the Gamma Knife.Materials and methods. The retrospective analysis included 31 patients (13 men and 18 women) with brain metastases, whose radiosurgery treatment was carried out in 2 sessions. The operation was contraindicated in all patients due to the risk of neurological deficits or due to the high anesthesiological risk.Results. Local control of metastases growth was achieved in 31 (96.9 %) of 32 foci 3 months after treatment, and in 92.5 and 83.8 %, after 6 and 12 months, respectively. The age &lt;50 years were associated with higher progression-free survival respectively. The median time of grade I–II radiation complications was 3.0 months, complications were observed in 11 (45.8 %) of 24 patients. Radiation complications of grade II (perifocal edema) were observed in 8 (33.3 %) patients, grade III (radionecrosis) – in 2 (8.3 %) patients. Overall survival at 6 and 12 months was 55.6 and 40.8 %, respectively (median 6.9 months), in patients receiving antitumor drug treatment – 80.0 and 56.8 %, respectively. All patients who did not received antitumor drug therapy died within 6 months.Conclusion. Two-stage radiosurgery, carried out in 2 sessions with an interval of 2–4 weeks, provides satisfactory local control with an acceptable level of post-radiation complications. This method of treatment can be used in patients with large brain metastases who are not subject to surgical treatment.

Brain size and neuron numbers drive differences in yawn duration across mammals and birds

Recent studies indicate that yawning evolved as a brain cooling mechanism. Given that larger brains have greater thermolytic needs and brain temperature is determined in part by heat production from neuronal activity, it was hypothesized that animals with larger brains and more neurons would yawn longer to produce comparable cooling effects. To test this, we performed the largest study on yawning ever conducted, analyzing 1291 yawns from 101 species (55 mammals; 46 birds). Phylogenetically controlled analyses revealed robust positive correlations between yawn duration and (1) brain mass, (2) total neuron number, and (3) cortical/pallial neuron number in both mammals and birds, which cannot be attributed solely to allometric scaling rules. These relationships were similar across clades, though mammals exhibited considerably longer yawns than birds of comparable brain and body mass. These findings provide further evidence suggesting that yawning is a thermoregulatory adaptation that has been conserved across amniote evolution.

Peter Goadsby, MD , PhD, Wins the Largest Brain Research Prize for Migraine Research

Peter Goadsby, MD , PhD, Wins the Largest Brain Research Prize for Migraine Research

Molecular evolutionary analysis of human primary microcephaly genes

BackgroundThere has been a rapid increase in the brain size relative to body size during mammalian evolutionary history. In particular, the enlarged and globular brain is the most distinctive anatomical feature of modern humans that set us apart from other extinct and extant primate species. Genetic basis of large brain size in modern humans has largely remained enigmatic. Genes associated with the pathological reduction of brain size (primary microcephaly-MCPH) have the characteristics and functions to be considered ideal candidates to unravel the genetic basis of evolutionary enlargement of human brain size. For instance, the brain size of microcephaly patients is similar to the brain size of Pan troglodyte and the very early hominids like the Sahelanthropus tchadensis and Australopithecus afarensis.ResultsThe present study investigates the molecular evolutionary history of subset of autosomal recessive primary microcephaly (MCPH) genes; CEP135, ZNF335, PHC1, SASS6, CDK6, MFSD2A, CIT, and KIF14 across 48 mammalian species. Codon based substitutions site analysis indicated that ZNF335, SASS6, CIT, and KIF14 have experienced positive selection in eutherian evolutionary history. Estimation of divergent selection pressure revealed that almost all of the MCPH genes analyzed in the present study have maintained their functions throughout the history of placental mammals. Contrary to our expectations, human-specific adoptive evolution was not detected for any of the MCPH genes analyzed in the present study.ConclusionBased on these data it can be inferred that protein-coding sequence of MCPH genes might not be the sole determinant of increase in relative brain size during primate evolutionary history.

Brain size predicts learning abilities in bees.

When it comes to the brain, bigger is generally considered better in terms of cognitive performance. While this notion is supported by studies of birds and primates showing that larger brains improve learning capacity, similar evidence is surprisingly lacking for invertebrates. Although the brain of invertebrates is smaller and simpler than that of vertebrates, recent work in insects has revealed enormous variation in size across species. Here, we ask whether bee species that have larger brains also have higher learning abilities. We conducted an experiment in which field-collected individuals had to associate an unconditioned stimulus (sucrose) with a conditioned stimulus (coloured strip). We found that most species can learn to associate a colour with a reward, yet some do so better than others. These differences in learning were related to brain size: species with larger brains—both absolute and relative to body size—exhibited enhanced performance to learn the reward-colour association. Our finding highlights the functional significance of brain size in insects, filling a major gap in our understanding of brain evolution and opening new opportunities for future research.

Personality structure in bottlenose dolphins (Tursiops truncatus).

Comparative studies can help identify selective pressures that contributed to species differences in the number and composition of personality domains. Despite being adapted to an aquatic lifestyle and last sharing a common ancestor with primates some 95 million years ago, bottlenose dolphins (Tursiops truncatus) resemble nonhuman primate species in several behavioral and cognitive traits. For example, like chimpanzees (Pan troglodytes), dolphins live in fission-fusion societies, use tools, and have relatively large brains. To determine the extent to which these and other factors contribute to the evolution of dolphin personality, we examined personality structure in 134 bottlenose dolphins. Personality was measured in 49 dolphins using a 42-item questionnaire, and in 85 dolphins using a version of the questionnaire that included 7 additional items. We found four domains. Three-Openness, Sociability, and Disagreeableness-resembled personality domains found in nonhuman primates and other species. The fourth, Directedness, was a blend of high Conscientiousness and low Neuroticism and was unique to dolphins. Unlike other species, but like humans, dolphins did not appear to have a strong Dominance domain. The overlap in personality structure between dolphins and other species suggests that selective pressures, such as those related to group structure, terrestrial lifestyles, morphology, and social learning or tool use are not necessary for particular domains to evolve within a species. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Optogenetic and chemogenetic control of an enzymatic reporter of neural activity

The brain's control of our thoughts, feelings, and behaviors stems from neural circuits, which perform logical operations based on the temporal patterns of neural activity and the connectivity of the neurons as the circuit traverses the brain. Recent studies have produced strategies for visualizing and controlling a circuit's neural activity. In some cases, specialized microscopy systems have enabled imaging of entire brain volumes on the timescale of neural activity and during behavior, enabling the reconstruction of neural circuitry at cellular resolution. However, recording neural activity from whole brain volumes to reconstruct neural circuitry is a significant challenge when working with larger brains, less specialized microscopes, or stimuli and behaviors that are not conducive to concurrent imaging. In these situations, strategies that enable permanent recording of neural activity during defined time windows for later readout would be highly beneficial. Here, we describe an approach for permanent recording of neural activity using calcium-dependent enzymatic activation of genetically encoded substrates. Our efforts focus on an engineered Tobacco Etch Virus (TEV) protease, which does not have endogenous substrates in vertebrate systems. We describe our strategy for engineering a calcium-dependent TEV protease that involves a split version of the enzyme with each half attached to the calcium-binding partners calmodulin and M13. These TEV fragments are designed so that, in the absence of neural activity, they will remain separate and inactive, but in the presence of neural activity and the resulting high calcium concentrations, the association of calmodulin and M13 will permit TEV reconstitution and enzyme activity. Once active, the split TEV protease can cleave a variety of genetically encoded substrates that link TEV protease activity with transcription of a desired gene or direct creation of a fluorophore. Finally, we will discuss controlling the split TEV protease and substrate association using opto- and chemogenetics approaches to provide precise spatial and temporal control over the time period of neural recording. This strategy will enable visualization and control of neurons activated by a sensory stimulus or behavior, permitting detailed analysis of neural circuitry over distant brain regions.

ASH: an Automatic pipeline to generate realistic and individualized chronic Stroke volume conduction Head models

Objective. Large structural brain changes, such as chronic stroke lesions, alter the current pathways throughout the patients’ head and therefore have to be taken into account when performing transcranial direct current stimulation simulations. Approach. We implement, test and distribute the first MATLAB pipeline that automatically generates realistic and individualized volume conduction head models of chronic stroke patients, by combining the already existing software SimNIBS, for the mesh generation, and lesion identification with neighborhood data analysis, for the lesion identification. To highlight the impact of our pipeline, we investigated the sensitivity of the electric field distribution to the lesion location and lesion conductivity in 16 stroke patients’ datasets. Main results. Our pipeline automatically generates 1 mm-resolution tetrahedral meshes including the lesion compartment in less than three hours. Moreover, for large lesions, we found a high sensitivity of the electric field distribution to the lesion conductivity value and location. Significance. This work facilitates optimizing electrode configurations with the goal to obtain more focal brain stimulations of the target volumes in rehabilitation for chronic stroke patients.

Multiple sclerosis-like NMOSD patients suffer severe worsening of status after fingolimod initiation

BackgroundInitial clinical manifestations of NMOSD may rarely overlap with MS. Fingolimod may trigger severe attacks in patients with NMOSD previously misdiagnosed as MS. These cases are rare and their pathophysiology remains elusive. MethodsWe recruited all NMOSD patients treated by fingolimod in a single-center cohort of Afro-Caribbean neuro-inflammatory patients in Fort-de-France (French West Indies). Six patients were collected from the literature. ResultsAmong 622 patients followed locally for MS, 101 received fingolimod and two suffered severe attacks revealing a typical NMOSD presentation. These two patients were found to have AQP4-IgG. The risk of misdiagnosed NMOSD in MS in our high-risk Afro-Caribbean patients was estimated to be 1.9% (0 to 4.7%). Among the whole cohort, relapses occurred within a month after fingolimod initiation in five patients. All attacks were severe and contrasted with previously benign attacks, suggesting a shift to a more severe disorder. An unusual finding in these patients was large brain lesions. ConclusionAQP4-IgG should be obtained before initiation of fingolimod in high-risk patients, especially in those from areas of high NMOSD prevalence.

Differentiation of brain metastases from small and non-small lung cancers using apparent diffusion coefficient (ADC) maps

BackgroundBrain metastases are particularly common in patients with small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with NSCLC showing a less aggressive clinical course and lower chemo- and radio sensitivity compared to SCLC. Early adequate therapy is highly desirable and depends on a reliable classification of tumor type. The apparent diffusion coefficient is a noninvasive neuroimaging marker with the potential to differentiate between major histological subtypes. Here we determine the sensitivity and specificity of the apparent diffusion coefficient to distinguish between NSCLC and SCLC.MethodsWe enrolled all NSCLC and SCLC patients diagnosed between 2008 and 2019 at the University Medical Center Göttingen. Cranial MR scans were visually inspected for brain metastases and the ratio of the apparent diffusion coefficient (ADC) was calculated by dividing the ADC measured within the solid part of a metastasis by a reference ADC extracted from an equivalent region in unaffected tissue on the contralateral hemisphere.ResultsOut of 411 enrolled patients, we detected 129 patients (83 NSCLC, 46 SCLC) with sufficiently large brain metastases with histologically classified lung cancer and no hemorrhage. We analyzed 185 brain metastases, 84 of SCLC and 101 of NSCLC. SCLC brain metastases showed an ADC ratio of 0.68 ± 0.12 SD, and NSCLC brain metastases showed an ADC ratio of 1.47 ± 0.31 SD. Receiver operating curve statistics differentiated brain metastases of NSCLC from SCLC with an area under the curve of 0.99 and a 95% CI of 0.98 to 1, p < 0.001. Youden's J cut-point is 0.97 at a sensitivity of 0.989 and a specificity of 0.988.ConclusionsIn patients with lung cancer and brain metastases with solid tumor parts, ADC ratio enables an ad hoc differentiation of SCLC and NSCLC, easily achieved during routine neuroradiological examination. Non-invasive MR imaging enables an early-individualized management of brain metastases from lung cancer.Trial registration: The study was registered in the German Clinical Trials Register (DRKS00023016).

Visual Outcomes in Surgically Treated Intracranial Meningiomas.

Intracranial meningiomas that arise from the medial sphenoid ridge, anterior clinoid process, tuberculum sellae, or planum sphenoidale often impair vision by compressing the optic nerves and optic chiasm. Although many studies have reported visual outcome following surgery for these tumors, documentation has often been incomplete and not validated by patient self-report. Retrospective study of 40 patients drawn from a single, academic, medical center. We used a unique method of assessing visual outcome based on whether the change in visual function affected the preoperatively better-sighted or worse-sighted eye in the belief that this method would correlate with effects on activities of daily living (ADL). To elicit patient self-reports of those effects, we conducted telephone interviews of 25 patients with a standard questionnaire. We also assessed putative ophthalmic, imaging, and surgical predictors of visual outcome. Visual improvement occurred in 61% of patients with preoperative monocular visual dysfunction, but only 22% of patients reported improvement in their ability to conduct ADL, and 17% lost vision. Visual outcomes were better in patients with preoperative binocular visual dysfunction, where visual improvement occurred in 73% and no patient lost vision in the preoperatively better-sighted eye. However, only 27% of patients with preoperative binocular visual dysfunction reported improvement in their ability to conduct ADL. Long duration of vision impairment, presence of optic disc pallor, large tumor size, and imaging-based preoperative optic canal involvement did not preclude a favorable visual outcome. Aggressive surgical reduction in displacement of the optic nerves was not necessary to obtain a favorable visual outcome and sometimes led to an unfavorable visual outcome. In this study, surgery often improved vision, especially in patients with preoperative binocular visual dysfunction. But patients indicated that the effect on their ability to perform ADL was more modest. Moreover, 17% of patients with preoperative monocular visual dysfunction lost vision in the only affected eye, often to a considerable degree. In those patients, surgery would be justified primarily to relieve the concern of having a large brain tumor and to prevent tumor growth. Preoperative ophthalmic and imaging features poorly predicted visual outcomes. Favorable visual outcomes occurred without aggressive surgical debulking of the tumors.

The impact of locomotion on the brain evolution of squirrels and close relatives

How do brain size and proportions relate to ecology and evolutionary history? Here, we use virtual endocasts from 38 extinct and extant rodent species spanning 50+ million years of evolution to assess the impact of locomotion, body mass, and phylogeny on the size of the brain, olfactory bulbs, petrosal lobules, and neocortex. We find that body mass and phylogeny are highly correlated with relative brain and brain component size, and that locomotion strongly influences brain, petrosal lobule, and neocortical sizes. Notably, species living in trees have greater relative overall brain, petrosal lobule, and neocortical sizes compared to other locomotor categories, especially fossorial taxa. Across millions of years of Eocene-Recent environmental change, arboreality played a major role in the early evolution of squirrels and closely related aplodontiids, promoting the expansion of the neocortex and petrosal lobules. Fossoriality in aplodontiids had an opposing effect by reducing the need for large brains.

Neonatal brain abscess development following fetal scalp electrode placement: a rare complication

A fetal scalp electrode (FSE) is a frequently used investigation during labor. However, it is an invasive procedure which can lead to complications. Our patient developed a very large brain abscess after initial superficial infection of the skin site due to an FSE. The patient was admitted to the hospital after an asymmetric growth of the skull was noticed with no further signs of clinical illness. MRI showed a very large brain abscess which was aspirated and treated with antibiotics for 10 weeks. A 2-year follow-up showed only a slight developmental delay in gross motor skills. Only once before a similar case has been described at which the patient developed a brain abscess after superficial infection of the scalp following an FSE. In both cases, the brain abscess was noticed due to an asymmetric growth of the skull without any further signs of clinical illness. A brain abscess has a high mortality and morbidity rate, and early diagnosis is vital for the optimal outcome. We therefore recommend to organize an out-patient clinical follow-up for every infant with a superficial infection of the skin site after placement of an FSE.