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Introduction: The corpus callosum, a principal commissural fibre-bundle of the brain, connects the two cerebral hemispheres, facilitating interhemispheric communication, cognitive and emotional processes. The anatomical definition of the isthmus of the corpus callosum remains unclear in literature with limited studies focusing on this region. This research addresses this gap by providing a detailed anatomical description of the isthmus of the corpus callosum in a South African cadaveric sample. Methods: Digital photographs of thirty embalmed cadaver brains were analysed and measurements of the corpus callosum and isthmus were taken, as seen on a midsagittal section. Results: The results revealed no significant differences in isthmus measurements when comparing the sex of the cadavers. The average length of the isthmus accounted for approximately 16.66 % of the total length of the corpus callosum. The isthmus constituted approximately 17.92 % of the corpus callosum surface area. Females tend to have a larger isthmus relative to the size of their corpus callosum. The prevalence of a posterior notch on the superior border of the corpus callosum was found to be approximately 46.66 % in the studied sample, with males showing a slightly higher prevalence. Conclusion: Since the isthmus constituted almost 20 % of the total surface area of the corpus callosum, as seen on midsagittal sections, it should be acknowledged as a fifth part. It should further be included in the undergraduate neuroanatomy curriculum and textbooks, which is currently lacking this information. This research recommends expanding the sample size, encompassing diverse demographics, employing fresh cadavers, and utilize three-dimensional imaging to understand the isthmus of the corpus callosum and its relevance to neuropsychiatric conditions and brain morphology.

Background: The size and shape of the adult corpus callosum (CC) may vary with gender. There is, however, less literature available on data involving the morphometry of CC among the Indian population. Aims and Objectives: To measure the size of CC using magnetic resonance imaging (MRI) scans of normal Indian adult females and males and identify gender-related differences, if any. Materials and Methods: The dimensions of CC were measured on MRI scans on a midsagittal section view belonging to 150 (59 females, 91 males) normal Indian adults (North India) using e-measurement tools. The measurements included the maximum length and height of CC, the thickness of various parts of CC, the CC index (CCI), and the distance of CC from the frontal and occipital poles of the cerebral hemisphere. The study was carried out in the Department of Anatomy in collaboration with the Department of Radiodiagnosis, King George’s Medical University, U.P., Lucknow, India. The data was analyzed using the statistical package for social sciences, 23rd version. Means were compared for significant differences using the independent unpaired t-test. Results: The mean length of the CC was found to be 6.94±0.63 cm; mean height was 2.57±0.43 cm; the mean thickness of the genu was 9.16±2.26 mm; the mean thickness of the body was 5.09±0.99 mm; the mean thickness of splenium was 9.10±2.22 mm; the mean distance from the frontal pole was 3.66±0.35 cm; the mean distance from the occipital pole was 5.70±0.74 cm; and the mean CCI calculations showed to be 3.37±0.56. All measurements were found to be greater in males as compared to females except mean height (males 2.56±0.47 cm; females 2.59±0.37 cm) and mean thickness of the body (males 5.04±0.94 mm; females 5.17±1.06 mm). A statistically significant difference was observed in the distance of CC from the frontal pole in our population with respect to gender (P=0.03). Conclusion: Based on observations made in the study, normative data of CC measurements was generated, and it was found that there was no significant gender-related difference in the morphology of CC; the only significant difference was in the distance of the genu from the frontal pole, which was greater in females as compared to males.

Background: The size and shape of the adult corpus callosum (CC) may vary with gender. There is, however, less literature available on data involving the morphometry of CC among the Indian population. Aims and Objectives: To measure the size of CC using magnetic resonance imaging (MRI) scans of normal Indian adult females and males and identify genderrelated differences, if any. Materials and Methods: The dimensions of CC were measured on MRI scans on a midsagittal section view belonging to 150 (59 females, 91 males) normal Indian adults (North India) using e-measurement tools. The measurements included the maximum length and height of CC, the thickness of various parts of CC, the CC index (CCI), and the distance of CC from the frontal and occipital poles of the cerebral hemisphere. The study was carried out in the Department of Anatomy in collaboration with the Department of Radiodiagnosis, King George’s Medical University, U.P., Lucknow, India. The data was analyzed using the statistical package for social sciences, 23rd version. Means were compared for significant differences using the independent unpaired t-test. Results: The mean length of the CC was found to be 6.94±0.63 cm; mean height was 2.57±0.43 cm; the mean thickness of the genu was 9.16±2.26 mm; the mean thickness of the body was 5.09±0.99 mm; the mean thickness of splenium was 9.10±2.22 mm; the mean distance from the frontal pole was 3.66±0.35 cm; the mean distance from the occipital pole was 5.70±0.74 cm; and the mean CCI calculations showed to be 3.37±0.56. All measurements were found to be greater in males as compared to females except mean height (males 2.56±0.47 cm; females 2.59±0.37 cm) and mean thickness of the body (males 5.04±0.94 mm; females 5.17±1.06 mm). A statistically significant difference was observed in the distance of CC from the frontal pole in our population with respect to gender (P=0.03). Conclusion: Based on observations made in the study, normative data of CC measurements was generated, and it was found that there was no significant gender-related difference in the morphology of CC; the only significant difference was in the distance of the genu from the frontal pole, which was greater in females as compared to males. [ABSTRACT FROM AUTHOR]

Abstract Background Stroke is a burdensome cerebral eventthat affects many aspects of daily activities such as motion, speech, memory, vision, and cognition. Intravascular laser irradiation of blood (ILIB) is a novel therapy, going beyond conventional rehabilitation modalities, that is effective in stroke recovery. Homocysteine ​​is an important risk factor associated with stroke. However, there are few studies that examine the relationship between ILIB treatment and the level of homocysteine. In recent years, researchers use the single-photon emission computed tomography (SPECT) scan of the brain to evaluate stroke patients and patients with a neurologicdeficit. The present report investigates the clinical effect of ILIB treatment on the level of serum homocysteine, the perfusion change of impaired brain region via SPECT, and the patient’s neurologic appearance. Casepresentation We focus on a case of a 62-year-old man with subacute stroke accompanied with left hemiparesis and hyperhomocysteinemia, who showed dramatic improvement in muscle power, a decreasing level of homocysteine, and increased blood flow of the right cerebral after three-courseILIB treatment. Conclusion We found that ILIB is effective in lowering serum levels of homocysteine and facilitating cerebral circulation for the patient with subacute stroke.

Background: Stroke is a burdensome cerebral eventthat affects many aspects of daily activities such as motion, speech, memory, vision, and cognition. Intravascular laser irradiation of blood (ILIB) is a novel therapy, going beyond conventional rehabilitation modalities, that is effective in stroke recovery. Homocysteine ​​is an important risk factor associated with stroke. However, there are few studies that examine the relationship between ILIB treatment and the level of homocysteine. In recent years, researchers use the single-photon emission computed tomography (SPECT) scan of the brain to evaluate stroke patients and patients with a neurologicdeficit. The present report investigates the clinical effect of ILIB treatment on the level of serum homocysteine, the perfusion change of impaired brain region via SPECT, and the patient's neurologic appearance.Casepresentation: We focus on a case of a 62-year-old man with subacute stroke accompanied with left hemiparesis and hyperhomocysteinemia, who showed dramatic improvement in muscle power, a decreasing level of homocysteine, and increased blood flow of the right cerebral after three-courseILIB treatment.Conclusion: We found that ILIB is effective in lowering serum levels of homocysteine and facilitating cerebral circulation for the patient with subacute stroke. [ABSTRACT FROM AUTHOR]

Hemispherectomy is an effective procedure used in the treatment of drug-resistant hemispheric epilepsy, especially in the pediatric population. A number of resective and disconnective techniques are used, and selection of surgical strategy is paramount to achieving successful results. Notably, disconnective (or functional) hemispherotomy maximizes the benefits of safe, surgical disconnection while minimizing hemispheric tissue resection, thereby avoiding some of the perioperative factors contributing to morbidity in traditional anatomical hemispherectomy procedures. In this video, the authors outline the principal surgical steps of disconnective hemispherotomy and highlight important technical factors leading to optimal outcomes in patients with refractory, oftentimes catastrophic, hemispheric epilepsy. The video can be found here: https://stream.cadmore.media/r10.3171/2024.4.FOCVID2436., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication.The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication., (© 2024, The Authors.)

Introduction: Cerebral hemispheres are the two main parts of human brain. Though, the cerebral hemispheres may appear to be identical, one hemisphere is functionally dominant over the other. They also exhibit physical variations. The dominance may be due to lateralisation of cortical functions. In about 90% of the total population, the left hemisphere is dominant over the right where the speech and language areas are located. These areas are situated within the Pars Opercularis (PO) and Pars Triangularis (PT) in the dominant hemisphere of the Lateral Sulcus (Sylvian Fissure). The interhemispheric asymmetry of the Sylvian Fissure (SF) may be the basis of cerebral dominance for language, which is less studied in human beings. These asymmetries are relative and vary according to the functions concerned. Therefore, knowledge of the interhemispheric asymmetries is helpful in neurological diagnosis and management. Aim: To measure the length of the lateral sulcus and its rami on both hemispheres and to study their interhemispheric asymmetry. Materials and Methods: A cross-sectional pilot study was done on 30 whole brains of embalmed adult human cadavers irrespective of sexes taken from the Institute of Anatomy of Madras Medical College, Tamil Nadu, India, between the months of June to August, 2017. The lateral sulcus was measured on the superolateral surface of the brain. All measurements were taken with the help of a thin copper wire placed on the surface, its ends being held in position with artery forceps. The wire was then placed on a graduated metal scale and the lengths of the anterior ascending, anterior horizontal, posterior rami and total length of the lateral sulcus were noted. A data sheet was made using Microsoft excel software and the mean length of each ramus was calculated. Results: The mean total length of the SF was noted to be 8.4±0.51 cm on the right side and 8.8±0.56 cm on the left. The mean length of stem of lateral sulcus was 2.5±0.4 cm and 2.6±0.3 cm on the right and left side, respectively. The mean length of the anterior ascending ramus was found to be 2.7±0.3 cm on the right side and 3.13±0.3 cm on the left side. The mean length of the anterior horizontal ramus was found to be 2.34±0.37 cm on the right side and 2.55±0.4 cm on the left side. The mean length of the posterior ramus was found to be 5.6±0.65 cm on the right side and 6.1±0.63 cm on the left side. Conclusion: The SF and their rami of the left side were longer than of the right side in most specimens. This signifies the functional asymmetry between right and left cerebral hemispheres which may be related to language lateralisation of human brain. This interhemispheric difference has been implicated in various genetic syndromes and behavioural disorders in children particularly involving language milestone.

This study was undertaken to document the normal features on gross morphology and morphometry of the olfactory brain and cerebral hemispheres of both sexes of African striped ground squirrel (Xerus erythropus) and to discuss the structure-function paradigm. The study was conducted by direct observation of ten (10) adult African striped ground squirrels comprising of five males and five females. The main morphological features were: a) a large club-shaped, non-pendulous olfactory bulb projecting from the cerebral hemispheres ventro-rostrally; b) cerebral hemisphere devoid of sulci and gyri; c) a well-developed corpus callosum connecting the cerebral hemisphere; and d.) a fornix which appeared as an arch shaped commissural fiber, consisting of a crus, a body and a commissure. Morphometric data values indicated that the males had statistically significant higher body and brain weights than the females. There was no significant statistical difference between sex in the mean values of the olfactory bulbs and cerebral hemispheres weight and dimensions (length and width). A significant statistical difference between sexes was reported with respect to the weight of the olfactory bulb (0.46 ± 0.03g in males and 0.32 ± 0.01g in females) and cerebral hemispheres width (1.87 ± 0.03cm in males and 1.79 ± 0.01cm in females). The well-developed corpus callosum and fornix, a very crucial organ in the function of formation and consolidation of memory, and the large size of the olfactory bulb, an organ for olfactory acuity supports the use of this rodent model for precise radio-tracking and identification of location. [ABSTRACT FROM AUTHOR]

Recurrent mutations in H3F3A that encodes the histone 3 variant H3.3, lead to amino acid substitutions including K27M and G34R/V-which are observed in high-grade gliomas (HGGs) of children and young adults. Previous studies have focused on gliomas with K27M mutation, whereas gliomas with G34R/V mutation have received little attention. Herein, we report three rare cases of glioblastoma (GBM) with H3.3 G34 mutation arising from a cerebral hemisphere in two children and one young adult. All three cases showed microscopic characteristics of central nervous system primitive neuroectodermal tumor (CNS-PNET, called CNS embryonal tumors in WHO 2016 Revised 4th Edition) and presented H3.3 G34 mutation. H3.3 G34-mutant brain tumors were formerly a group of histopathologically distinct neoplasms, involved in GBM, CNS-PNET, and astroblastoma. However, recent studies have demonstrated that different CNS tumors with H3.3 G34 mutation display coherent epigenetic signatures, implying a single biological origin. Correspondingly, our three cases showed high consistency in tumor location, histological morphology, and molecular phenotype. Their immunophenotypes are similar to astrocytoma, with ATRX loss and TP53 mutation. Therefore it suggests that these H3.3 G34-mutant brain tumors may be a rare entity of HGG.

The effect of orthographic neighbourhood size (N) on lexical decision reaction time differs when words are presented in the left or right visual fields. Evidence suggests a facilitatory N effect (i.e., faster reaction times for words with larger neighbourhoods) in the left visual field. However, the N effect in the right visual field remains controversial: it may have a weaker facilitative role or it may even be inhibitory. In a pre-registered online experiment, we replicated the interaction between N and visual field and provided support for an inhibitory N effect in the right visual field. We subsequently conducted a pre-registered systematic review and meta-analysis to synthesise the available evidence and determine the direction of N effects across visual fields. Based on the evidence, it would seem the effect is inhibitory in the right visual field. Furthermore, the size of the N effect is considerably smaller in the right visual field. Both studies revealed considerable heterogeneity between participants and studies, and we consider the implications of this for future work.

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Background: The human paracentral lobule (PCL) is the medial continuation of the precentral and postcentral gyri. It has important functional area related to the lower limb and perineum. Its visible surface that corresponds to magnetic resonance imaging scout images varies in morphology, so it requires exact data. Studies related to such data are rare. With such a facile, we studied the morphology and morphometry of PCL. Materials and Methods: Fifty formalin-fixed adult human brains dissected in the midsagittal plane were used in this study. First, the morphological types of PCL and its boundary were determined, followed by morphometry of its extrasulcal surface using digital vernier calipers. Measurements were done along the anteroposterior axis (length) and vertical axis (height). In addition to that, the extent of motor and sensory area into PCL was also measured. Results: Three distinct morphological types of PCL were found: continuous (2%), partially segmented (91%), and completely segmented type (7%). In completely segmented type, a short transitional lobulolimbic gyrus was also found in three cases. The mean extrasulcal surface of the left PCL was significantly larger, both in males (left 10.67 cm2 vs. right 8.80 cm2) and in females (left 8.80 cm2 vs. right 6.99 cm2). Irrespective of gender and sidedness, motor area was significantly larger than the sensory area. Conclusion: Reported data will be useful in diagnosis and treatment of diseases affecting the human PCL. Variations in the distribution of sensorimotor cortex over PCL may help further assessment of hemispheric lateralization and the location of central sulcus as a reliable indicator of cytoarchitectonic borders. [ABSTRACT FROM AUTHOR]

The effect of orthographic neighbourhood size (N) on lexical decision reaction time differs when words are presented in the left or right visual fields. Evidence suggests a facilitatory N effect (i.e., faster reaction times for words with larger neighbourhoods) in the left visual field. However, theNeffect in the right visual field remains controversial: it may have a weaker facilitative role or it may even be inhibitory. In a pre-registered online experiment, we replicated the interaction between N and visual field and provided support for an inhibitory N effect in the right visual field. We subsequently conducted a pre-registered systematic review and meta-analysis to synthesise the available evidence and determine the direction of N effects across visual fields. Based on the evidence, it would seem the effect is inhibitory in the right visual field. Furthermore, the size of theN effect is considerably smaller in the right visual field. Both studies revealed considerable heterogeneity between participants and studies, and we consider the implications of this for future work. [ABSTRACT FROM AUTHOR]

Cognitive performance and cerebral hemispheric function are known to vary with fluctuating levels of estradiol and progesterone across the menstrual cycle in naturally cycling females. However, the literature is mixed with regard to how each hemisphere may be affected by elevated ovarian hormones. To better understand this, the current study employed a dual-task paradigm to examine potential shifts in hemispheric involvement for a verbal problem-solving task across the menstrual cycle in 30 right-handed, normally cycling young adult females (18–21 years old). To our knowledge, no study to date has utilized dual-task procedures to directly investigate the potential shifts in hemispheric function across the menstrual cycle. Specifically, participants were tested during both menses and their estimated midluteal phase where they engaged in repetitive unilateral finger-tapping while concurrently solving anagrams silently or aloud. Analysis of finger-tapping interference during the dual-task conditions revealed that solving anagrams silently was lateralized to the left hemisphere while solving anagrams aloud yielded a pattern of more bilateral hemispheric involvement, both of which were consistent across both menses and midluteal phases. Analysis of cognitive performance, however, revealed that silent anagrams performance while tapping with the right, but not left, hand significantly increased during the midluteal phase. Consistent with a number of other studies using different methodological approaches, the current dual-task findings suggest that when ovarian hormone levels are putatively elevated, there is enhanced recruitment of left hemisphere resources while performing a lateralized verbal task. [ABSTRACT FROM AUTHOR]

Background Exophytic growth (EG), wherein the tumor mass grows beyond the neuraxial boundary formed by pia mater, remains a rare pattern of glioma growth. It has been described in gliomas at several locations like the brainstem, cerebellum, suprasellar area, spinal cord, and insula. However, EG in hemispheric grade 2 astrocytomas, particularly affecting the convexity subarachnoid space, as against the more spacious basal subarachnoid space, is exceedingly rare. To the best of our knowledge, there is only 1 such case reported in the English literature. Due to the extreme rarity, little is known about these tumors, particularly the mechanisms underlying the EG and their possible clinical implications. Case Description A 32-year-old woman presented with partial motor seizures without any neurologic signs. On magnetic resonance imaging of the head, a nonenhancing, T2-hyperintense, right frontal lobe lesion was noted. The majority of the lesion was occupying the adjacent subdural space while still remaining in continuity with the intra-axial globular component. During surgery, the exophytic nature of the lesion was confirmed. We performed maximal resection of the exophytic portion with subtotal excision of the intra-axial component. She recovered uneventfully after surgery and subsequently received external beam radiotherapy for the residual tumor. Conclusion Although extremely rare, cerebral hemispheric grade 2 astrocytomas may have an EG pattern. The exact mechanisms underlying this are not clearly known. More such cases need to be reported so that we can decipher the true nature of these tumors. [ABSTRACT FROM AUTHOR]

Purpose: Models designed to study neurovascular coupling (NVC) describe a possible cerebral hemisphere dominance dependent on task completed and preference in handedness. We investigated whether passive arm manoeuvre performed with dominant (Dom-Arm) or non-dominant arm (ND-Arm) stimulated haemodynamic differences in either contralateral (Cont-H) or ipsilateral (Ipsil-H) cerebral hemisphere.Methods: Healthy individuals lying in supine position, had measurements of beat-to-beat blood pressure (BP, mmHg), electrocardiogram (HR, bpm), end-tidal CO2 (etCO2, mmHg), and bilateral insonation of the middle cerebral arteries (MCA, cm s-1). Arm movement was performed for 60 s with passive flexion and extension of the elbow (1 Hz), before manoeuvre was repeated on other arm. Data were normalised and effect of treatment was analysed for differences between manoeuvres and within each time period.Results: Seventeen (eight males) healthy volunteers, aged 56 ± 7 years, were studied. Dom-Arm and ND-Arm manoeuvres stimulated a comparable temporal response in peripheral and cerebral haemodynamic parameters between Cont-H and Ipsil-H.Conclusions: Both manoeuvres can be used to evoke similar bilateral MCA responses in assessing NVC. This finding should lead to more efficient protocols when using passive arm movement for NVC studies in healthy subjects. [ABSTRACT FROM AUTHOR]

Working memory capacity, the amount of information that may be maintained in mind over a period of seconds, is extremely limited, to a handful of items. Some evidence exists that the number of visual items that may be maintained in working memory is independent for the two hemifields. To test this idea, we trained monkeys to perform visual working memory tasks that required maintenance in memory of the locations and/or shapes of 3–5 visual stimuli. We then tested whether systematic performance differences were present for stimuli concentrated in the same hemifield, vs. distributed across hemifields. We found little evidence to support the expectation that working memory capacity is independent in the two hemifields. Instead, when an advantage of stimulus arrangement was present, it involved multiple stimuli presented in the same hemifield. This conclusion was consistent across variations of the task, performance levels, and apparent strategies adopted by individual subjects. This result suggests that factors such as grouping that favor processing of stimuli in relative proximity may counteract the benefits of independent processing in the two hemispheres. Our results reveal an important property of working memory and place constraints on models of working memory capacity.