Shape variability of the central sulcus in the developing brain: a longitudinal descriptive and predictive study in preterm infants.

Despite growing evidence of links between sulcation and function in the adult brain, the folding dynamics, occurring mostly before normal-term-birth, is vastly unknown. Looking into the development of cortical sulci in babies can give us keys to address fundamental questions: what is the sulcal shape variability in the developing brain? When are the shape features encoded? How are these morphological parameters related to further functional development? In this study, we aimed to investigate the shape variability of the developing central sulcus, which is the frontier between the primary somatosensory and motor cortices. We studied a cohort of 71 extremely preterm infants scanned twice using MRI - once around 30 weeks post-menstrual age (w PMA) and once at term-equivalent age, around 40w PMA -, in order to quantify the sulcus's shape variability using manifold learning, regardless of age-group or hemisphere. We then used these shape descriptors to evaluate the sulcus's variability at both ages and to assess hemispheric and age-group specificities. This led us to propose a description of ten shape features capturing the variability in the central sulcus of preterm infants. Our results suggested that most of these features (8/10) are encoded as early as 30w PMA. We unprecedentedly observed hemispheric asymmetries at both ages, and the one captured at term-equivalent age seems to correspond with the asymmetry pattern previously reported in adults. We further trained classifiers in order to explore the predictive value of these shape features on manual performance at 5 years of age (handedness and fine motor outcome). The central sulcus's shape alone showed a limited but relevant predictive capacity in both cases. The study of sulcal shape features during early neurodevelopment may participate to a better comprehension of the complex links between morphological and functional organization of the developing brain.

Sex and Age Differences in Default Mode Network Functional Correlation After Traumatic Brain Injury

The extent to which brain functional correlations (FCs) are modulated by age and sex is unknown. We studied default mode network (DMN) FC changes in 136 participants with mild traumatic brain injury (mTBI; 52 females, age range: 19 – 79 years, age μ = 42, age σ = 17; 72 participants younger than 40). Structural and functional magnetic resonance images (MRIs) were acquired ~1 week and ~6 months post-injury; the FreeSurfer Functional Analysis STream (FS-FAST) was used for group-level FC comparisons across sexes and age groups (younger vs. older than 40). FC seeds were two sub-networks of the DMN, M1 and M2, defined by the standard Yeo parcellation scheme. For M1, clusters with significant FC differences across sexes were in the right paracentral lobule, central sulcus, postcentral gyrus, superior frontal gyrus, and precentral sulcus (p = 0.0001), and in the left paracentral lobule and central sulcus (p = 0.022). For M2, clusters spanned the right postcentral gyrus, middle occipital gyrus, transverse occipital sulcus, and central sulcus (p = 0.0001), the left precuneus and inferior parietal lobe (p = 0.0096). Females either exhibited no significant FC change or underwent FC increases. Males underwent significant FC decreases within all clusters, suggesting their increased vulnerability to mTBI-related effects. Clusters whose FCs differed significantly across age groups were localized to the left superior temporal gyrus (p = 0.0078), highlighting the vulnerability of temporal regions to age effects. Future studies should explore the age × sex interaction and uncover the mechanisms for these observed findings.

Age-related changes in the human primary motor cortex: A macroscopic and microscopic study

Background: Cerebral hemisphere has outer gray matter and inner white matter. The cerebrum is folded into gyri and sulci in order to accommodate it in the skull. The thickness of the gray matter varies at sulci and gyri and the mean thickness may be from 1.5 mm to 4.0 mm. Aims and Objectives: (1) To demonstrate the cells and laminar architecture of the primary motor cortex with different stains. (2) To find out the age-related changes in the thickness of the primary motor cortex and the depth of the central sulcus. Materials and Methods: Cross-sectional study was done using 50 adult human brains and 10 fetal brains obtained from the Department of Forensic medicine and OBG, respectively, in a Government Medical College in Kerala during 2001–2003. At autopsy, the central sulcus and the precentral gyrus were identified. Depth of central sulcus and thickness of precentral gyrus, in upper, middle, and lower parts were measured using Vernier calipers. Tissue specimens were taken from the precentral gyrus and after fixation in 10% formalin, hematoxylin, and eosin-stained slides were prepared and viewed under a light microscope identifying six laminae. Using an oculo micrometer, width of the six laminae were measured. Pyramidal cells and stellate cells were observed and their size measured. Results: Depth of the central sulcus was more on the right side but it was minimal on the middle part of both sides. The thickness of the precentral gyrus varied from 1 to 6 mm. Maximum thickness of 6 mm was found in the middle and lower parts in the 21–30 age group. Lamina 5 was the widest of all laminae. Maximum width of 1000 μ was noted in the 41–50 age group. Conclusion: Grey matter thickness of 1-6 mm noted in this study was comparable with other studies. Pyramidal cells of varying sizes were seen in all sections with different staining methods. It was confirmed that neuronal loss is inevitable as age advances.

Surgery for Epilepsy Involving Rolandic and Peri-Rolandic Cortex

PurposeTo evaluate the risk factors associated with motor deficit following surgeries involving rolandic & peri-rolandic cortex and to introduce our surgical experiences dealing with lesions in this region.MethodsWe retrospectively reviewed patients who experienced drug-refractory epilepsies and received surgeries in our hospital. Medical records were carefully studied, and patients with lesions located in the rolandic & peri-rolandic cortex were screened. Those with detailed follow-up information were included. Lesion locations, resected regions, and invasive exploration techniques were studied to assess their relationship with the postoperative motor deficit.ResultsA total of 41 patients with lesions located in the rolandic or peri-rolandic cortex were included in this study. Of all these patients, 23 (56.10%) patients suffered from a transient motor deficit and 2 (4.88%) with a permanent disability after surgery. All eight patients with the anterior bank of precentral sulcus resected experienced motor deficit, and six of them gradually recovered within half a year. Seven patients with the anterior half of precentral gyrus resected did not experience permanent disability. A total of 14 (34.15%) patients received invasive exploration, and one of them had a permanent disability.ConclusionsThe anterior bank of the central sulcus is indispensable for motor functions, and the destruction of this region would inevitably cause a motor deficit. The upper part of the central sulcus could also be removed without significant neurological impairment if there is an epileptogenic lesion.

Asleep or awake motor mapping for resection of perirolandic glioma in the nondominant hemisphere? Development and validation of a multimodal score to tailor the surgical strategy

OBJECTIVE Resection of glioma in the nondominant hemisphere involving the motor areas and pathways requires the use of brain-mapping techniques to spare essential sites subserving motor control. No clear indications are available for performing motor mapping under either awake or asleep conditions or for the best mapping paradigm (e.g., resting or active, high-frequency [HF] or low-frequency [LF] stimulation) that provides the best oncological and functional outcomes when tailored to the clinical context. This work aimed to identify clinical and imaging factors that influence surgical strategy (asleep motor mapping vs awake motor mapping) and that are associated with the best functional and oncological outcomes and to design a “motor mapping score” for guiding tumor resection in this area. METHODS The authors evaluated a retrospective series of patients with nondominant-hemisphere glioma—located or infiltrating within 2 cm anteriorly or posteriorly to the central sulcus and affecting the primary motor cortex, its fibers, and/or the praxis network—who underwent operations with asleep (HF monopolar probe) or awake (LF and HF probes) motor mapping. Clinical and imaging variables were used to design a motor mapping score. A prospective series of patients was used to validate this motor mapping score. RESULTS One hundred thirty-five patients were retrospectively analyzed: 69 underwent operations with asleep (HF stimulation) motor mapping, and 66 underwent awake (LF and HF stimulation and praxis task evaluation) motor mapping. Previous motor (strength) deficit, previous treatment (surgery/radiotherapy), tumor volume > 30 cm3, and tumor involvement of the praxis network (on MRI) were identified and used to design the mapping score. Motor deficit, previous treatment, and location within or close to the central sulcus favor use of asleep motor mapping; large tumor volume and involvement of the praxis network favor use of awake motor mapping. The motor mapping score was validated in a prospective series of 52 patients—35 underwent operations with awake motor mapping and 17 with asleep motor mapping on the basis of the score indications—who had a low rate of postoperative motor-praxis deficit (3%) and a high extent of resection (median 97%; complete resection in > 70% of patients). CONCLUSIONS Extensive resection of tumor involving the eloquent areas for motor control is feasible, and when an appropriate mapping strategy is applied, the incidence of postoperative motor-praxis deficit is low. Asleep (HF stimulation) motor mapping is preferable for lesions close to or involving the central sulcus and/or in patients with preoperative strength deficit and/or history of previous treatment. When a patient has no motor deficit or previous treatment and has a lesion (> 30 cm3) involving the praxis network, awake mapping is preferable.

A study on the age related anatomical variations of some of the cerebral cortical sulci of human brain

Background: The sulcal patterns may be useful in studying the mechanisms of both neuro developmental and neuro degenerative changes that occur during brain maturation and ageing. Magnetic resonance imaging has facilitated the non-invasive study of human cerebral and cognitive development. Aims and Objective: To find out the age related anatomical variations of some of the cerebral cortical sulci and gyri of the brain. Materials and Methods: The study was done using the MRI images of brain of normal healthy adults aged between 20-70 years. A total of 200 images were analysed consisting of that from 119 male subjects and 81 female subjects from the Department of Radiodiagnosis, Government Medical College Kottayam. Results: Using statistical analysis it was found that as the age advances there was decrease in the depth, in case of central sulcus, pre-central sulcus and post-central sulcus. The width of the pre-central sulcus and post-central sulcus was found to increase with age. The changes in the width of the central sulcus were not significant. Conclusion: The observations of the undertaken study indicated that age changes do occur in the sulci ofthe brain and there was a sequential change in relation to the different periods of adult life. These changes are probably due to the volume loss of the brain due to the atrophy that occurs during aging.