Phylogenetic differences in the morphology and shape of the central sulcus in great apes and humans: implications for the evolution of motor functions.

The central sulcus divides the primary motor and somatosensory cortices in many anthropoid primate brains. Differences exist in the surface area and depth of the central sulcus along the dorso-ventral plane in great apes and humans compared to other primate species. Within hominid species, there are variations in the depth and aspect of their hand motor area, or knob, within the precentral gyrus. In this study, we used post-image analyses on magnetic resonance images to characterize the central sulcus shape of humans, chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and orangutans (Pongo pygmaeus and Pongo abelii). Using these data, we examined the morphological variability of central sulcus in hominids, focusing on the hand region, a significant change in human evolution. We show that the central sulcus shape differs between great ape species, but all show similar variations in the location of their hand knob. However, the prevalence of the knob location along the dorso-ventral plane and lateralization differs between species and the presence of a second ventral motor knob seems to be unique to humans. Humans and orangutans exhibit the most similar and complex central sulcus shapes. However, their similarities may reflect divergent evolutionary processes related to selection for different positional and habitual locomotor functions.

Passive localization of the central sulcus during sleep based on intracranial EEG.

We test the performance of a novel operator-independent EEG-based method for passive identification of the central sulcus (CS) and sensorimotor (SM) cortex. We studied seven patients with intractable epilepsy undergoing intracranial EEG (icEEG) monitoring, in whom CS localization was accomplished by standard methods. Our innovative approach takes advantage of intrinsic properties of the primary motor cortex (MC), which exhibits enhanced icEEG band-power and coherence across the CS. For each contact, we computed a composite power, coherence, and entropy values for activity in the high gamma band (80-115) Hz of 6-10 min of NREM sleep. Statistically transformed EEG data values that did not reach a threshold (th) were set to 0. We computed a metric M based on the transformed values and the mean Euclidian distance of each contact from contacts with Z-scores higher than 0. The last step was implemented to accentuate local network activity. The SM cortex exhibited higher EEG-band-power than non-SM cortex (P < 0.0002). There was no significant difference between the motor/premotor and sensory cortices (P < 0.47). CS was localized in all patients with 0.4 < th < 0.6. The primary hand and leg motor areas showed the highest metric values followed by the tongue motor area. Higher threshold values were specific (94%) for the anterior bank of the CS but not sensitive (42%). Intermediate threshold values achieved an acceptable trade-off (0.4: 89% specific and 70% sensitive).

Localization of the central sulcus using the distinctive high signal intensity of the paracentral lobule on T1-weighted images.

PURPOSE: The central sulcus is an important landmark in the brain. This study aimed to investigate the distinctive signal of the paracentral lobule (PL) on T1-weighted images (T1WIs; the white PL sign) and evaluate its usefulness as a new method of identifying the central sulcus. METHODS: T1WIs of the brain of 96 participants (age, 58.9 ± 17.9 years; range, 8-87 years) scanned at 3-T MR system were retrospectively reviewed. First, we qualitatively analyzed the signal of the cortex of the PL by comparing it with that of the ipsilateral superior frontal gyrus on a 4-point grading score. Second, we compared the cortical signal intensity and gray/white-matter contrast between the PL and superior frontal gyrus. Third, we evaluated the usefulness of the PL signal for identifying the central sulcus. RESULTS: The PL cortex was either mildly hyperintense (grade 2) or definitely hyperintense (grade 3) in comparison with that of superior frontal cortex in all participants. The signal intensity of the PL cortex was significantly higher than that of the superior frontal cortex (p < 0.001), whereas the gray/white-matter contrast of the PL was weaker than that of the superior frontal gyrus (p < 0.001). The central sulci were identified with 94.3% accuracy (181/192) using the new method. CONCLUSION: The white PL sign may be helpful in identifying the central sulcus, and this approach can be recognized as a new method for identification of the central sulcus.

Tight Coupling between Morphological Features of the Central Sulcus and Somatomotor Body Representations: A Combined Anatomical and Functional MRI Study.

Pioneering research established the concept of somatotopic organization of the primary motor and somatosensory cortex along the central sulcus as depicted in the widely known schematic illustration (the "homunculus") by Penfield and colleagues. With the exception of the hand, however, a precise relationship between morphological features of the central sulcus and the representation of various parts of the body has not been addressed. To investigate whether such relations between anatomical features and functional body representations exist, we first examined central sulcus morphology in detail and then conducted a functional magnetic resonance imaging experiment to establish somatomotor representations. This study established that the central sulcus is composed of five distinct sulcal segments and demonstrated that each segment relates systematically to the sensorimotor representation of distinct parts of the body. Thus, local morphology predicts the localization of body representations with precision, raising fundamental questions regarding functional and morphological differentiation.

"Plis de passage" Deserve a Role in Models of the Cortical Folding Process.

Cortical folding is a hallmark of brain topography whose variability across individuals remains a puzzle. In this paper, we call for an effort to improve our understanding of the pli de passage phenomenon, namely annectant gyri buried in the depth of the main sulci. We suggest that plis de passage could become an interesting benchmark for models of the cortical folding process. As an illustration, we speculate on the link between modern biological models of cortical folding and the development of the Pli de Passage Frontal Moyen (PPFM) in the middle of the central sulcus. For this purpose, we have detected nine interrupted central sulci in the Human Connectome Project dataset, which are used to explore the organization of the hand sensorimotor areas in this rare configuration of the PPFM.

Genetic Factors and Orofacial Motor Learning Selectively Influence Variability in Central Sulcus Morphology in Chimpanzees (Pan troglodytes).

Captive chimpanzees (Pan troglodytes) have been shown to learn the use of novel attention-getting (AG) sounds to capture the attention of humans as a means of requesting or drawing their attention to a desired object or food. There are significant individual differences in the use of AG sounds by chimpanzees and, here, we examined whether changes in cortical organization of the central sulcus (CS) were associated with AG sound production. MRI scans were collected from 240 chimpanzees, including 122 that reliably produced AG sounds and 118 that did not. For each subject, the depth of CS was quantified along the superior-inferior plane with specific interest in the inferior portion corresponding to the region of the motor cortex where the mouth and orofacial movements are controlled. Results indicated that CS depth in the inferior, but not superior, portion was significantly greater in chimpanzees that reliably produced AG sounds compared with those who did not. Quantitative genetic analyses indicated that overall CS surface area and depth were significantly heritable, particularly in the superior regions, but less so in the inferior and central portions. Further, heritability in CS depth was altered as a function of acquisition of AG sounds. The collective results suggest that learning to produce AG sounds resulted in region-specific cortical reorganization within the inferior portion of the CS, a finding previously undocumented in chimpanzees or any nonhuman primate.SIGNIFICANCE STATEMENT Recent studies in chimpanzees (Pan troglodytes) have shown that some can learn to produce novel sounds by configuring different orofacial movement patterns and these sounds are used in communicatively relevant contexts. Here, we examined the neuromorphological correlates in the production of these sounds in chimpanzees. We show that chimpanzees that have learned to produce these sounds show significant differences in central sulcus (CS) morphology, particularly in the inferior region. We further show that overall CS morphology and regions within the superior portion are significantly heritable, whereas central and inferior portions of the CS are not. The collective findings suggest chimpanzees exhibit cortical plasticity in regions of the brain that were central to the emergence of speech functions in humans.

Shape of the Central Sulcus and Disability After Subcortical Stroke: A Motor Reserve Hypothesis.

BACKGROUND AND PURPOSE: Both brain and cognitive reserves modulate the clinical impact of chronic brain diseases. Whether a motor reserve also modulates the relationships between stroke and disability is unknown. We aimed to determine whether the shape of the central sulcus, a marker of the development of underlying motor connections, is independently associated with disability in patients with a positive history of small subcortical ischemic stroke. METHODS: Shapes of central sulci were reconstructed from high-resolution magnetic resonance imaging and ordered without supervision according to a validated algorithm in 166 patients with a positive history of small subcortical ischemic stroke caused by CADASIL (Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy), a severe monogenic cerebral small vessel disease affecting young patients. Ordinal logistic regression modeling was used to test the relationships between modified Rankin scale, a disability scale strongly weighted toward motor disability, and sulcal shape. RESULTS: Modified Rankin scale was strongly associated with sulcal shape, independent of age, sex, and level of education (proportional odds ratio =1.19, 95% confidence interval =1.06-1.35; P=0.002). Results remained significant after further adjustment for brain atrophy, volume of lacunes, and volume of white matter hyperintensities of presumed vascular origin. CONCLUSIONS: The severity of disability in patients with a positive history of small subcortical ischemic stroke caused by a severe cerebral small vessel disease is related to the shape of the central sulcus, independently of the main determinants of disability. These results support the concept of a motor reserve that could modulate the clinical severity in patients with a positive history of small subcortical ischemic stroke.

Assignment Confidence in Localization of the Hand Motor Cortex: Comparison of Structural Imaging With Functional MRI.

OBJECTIVE: The purpose of this study was to assign confidence levels to structural MRI and functional MRI (fMRI) for localization of the primary motor cortex. MATERIALS AND METHODS: Ninety-one fMRI studies with at least one motor task (178 hemispheres) were identified. Three anatomic assessments were used to localize the primary motor cortex: relation between the superior frontal sulcus and precentral sulcus; cortical thickness; and configuration of the precentral knob. In 105 hemispheres, interreader agreement was assessed for two investigators with different experience levels. Confidence ratings from 0 to 5 (0, no confidence; 5, 100% confidence) were assigned for fMRI and each anatomic localization method. RESULTS: Cortical thickness had the highest confidence rating (mean, 4.90 ± 0.47 [SD]) with only one failure. The relation between the superior frontal sulcus and precentral sulcus had the lowest confidence rating (4.33 ± 0.91) with three failures. The greatest statistical significance was observed for the cortical thickness and superior frontal sulcus-precentral sulcus methods (post hoc Bonferroni test, p < 0.001). Confidence rating scores were significantly higher for the cortical thickness sign than for fMRI results (4.72 ± 0.54) for a single motor task (post hoc Bonferroni test, p = 0.006); however, the mean confidence rating for fMRI improved to 4.87 ± 0.36 when additional motor tasks were performed. Interreader differences were least for the cortical thickness sign (paired t test, t = 4.25, p < 0.001). CONCLUSION: Cortical thickness is a better anatomic landmark than fMRI localization for assigning confidence regarding localization of the primary motor cortex; however, localization of motor function is more specific when combined with fMRI findings. Multiple techniques can be used to increase confidence in identifying the hand motor cortex.

Signal intensity of superficial white matter on phase difference enhanced imaging as a landmark of the perirolandic cortex.

Background The superficial white matter (SWM), which fills the space between the deep white matter and the cortex, has not been well characterized. Purpose To determine whether the assessment of the relative signal intensity (SI) of the SWM in the precentral and postcentral gyri on phase difference enhanced (PADRE) images contributes in establishing anatomical landmark. Material and Methods The study population consisted of 43 normal subjects (28 women, 15 men; mean age, 52.9 years; age range, 22-90 years). By the consensus of two observers, the precentral gyri, postcentral gyri, and superior frontal cortex (SFC) were identified based on the established anatomical methods. The SI of the SWM in the precentral and postcentral gyri on PADRE images was divided into three grades in comparison with that of the SFC: Grade I, isointense; Grade II, slightly hypointense; and Grade III, markedly hypointense. Results The SWM in the precentral and postcentral gyri showed hypointensity on PADRE images. In the SI analyses of the PADRE images, the Grade I, Grade II, and Grade III appearances were found in one (1%), 20 (23%), and 65 (76%) of the 86 precentral gyri (43 subjects), respectively, and in one (1%), 23 (27%), and 62 (72%) of the 86 postcentral gyri, respectively. Conclusion On PADRE images, the perirolandic SWM showed hypointensity compared to other cerebral cortices, which probably reflects differences in the concentrations of the nerve fibers, as well as the higher myelin content. PADRE may be useful for the identification of the central sulcus by assessing the SI of the SWM.

Morphometric analysis of the main brain sulci and clinical implications: Radiological and cadaveric study.

Objective: Sulci and gyri of the cerebrum can be easily identified with the aid of radiology but are difficult to locate during surgical operations, owing to anatomical variations and the surgical approach of the sulci through a small aperture. Therefore, this study was performed to locate the main sulci of the brain by using various anatomical landmarks in cadaveric brain specimens and CT scan images. Methods: In 31 cadaveric brain specimens (17 right and 14 left hemispheres) from people of unknown sex, 21 parameters associated with important sulci of the brain were studied. CT scan images for 150 patients in three age groups were examined. The patient IDs were categorized into 50 patients in each of the following age groups: 20-40 yr, 41-60 yr and 61-80 yr. Ten parameters were studied. The data were statistically analyzed in SPSS software. Results: In the cadaveric brain specimens, comparisons of right and left hemispheres indicated that only the posterior part of the calcarine sulcus showed a significant difference (p = 0.0394). In CT scans within each age group, comparison of the right and left sides in males and females showed significant differences for many parameters (e.g., calcarine sulcus to occipital pole: right p = 0.0025; left p = 0.0009). Comparisons between male and female parameters also showed significant differences. Conclusion: This study aids in identifying the important functional areas of the brain situated near the sulci, given that the sulci are connected to the gyral functions and act as a barrier for the gyri. The findings may facilitate neurosurgery operations.

Microsurgical Treatment for a Cerebral Arteriovenous Malformation of the Central Sulcus.

Arteriovenous malformations (AVMs) are congenital neurovascular disorders frequently manifested in young adults. The clinical presentation is variable and depends on its location, size, and ability to steal flow from adjacent areas, but it depends mainly on the occurrence of bleeding.1 The treatment of these lesions when located in eloquent areas, especially around the central sulcus, is controversial. Surgical resection of an AVM in the central lobe may cause postoperative sensorimotor deficits because this anatomic region includes the precentral and postcentral gyri on the lateral surface and paracentral lobule on the medial surface.2 AVMs can be successfully treated by surgery, but this treatment may pose unacceptable risks to the patient if the AVM involves an eloquent cortex. We consider that surgical removal of many of these lesions is feasible when preoperative planning is performed,3 when it is based on deep anatomic knowledge, and particularly when using a refined microsurgical technique.1 In this 3-dimensional Video 1, we present a case of a cerebral AVM of the central sulcus in which we achieved complete resection with microsurgical treatment without any neurologic sequelae for the patient. The patient consented to publication of images.

Assessment of Direct Signs of Localization of Central Sulcus in Normal Axial Computed Tomography Scan of Brain.

BACKGROUND: Central sulcus is relatively constant in anatomy and provides an important landmark in lesion localization in high convexity-parasagittal region. The purpose of this study was to evaluate various direct signs of localization of central sulcus in normal axial computed tomography scan of brain. METHODS: This cross-sectional descriptive study was conducted in 377 patients with normal findings in computed tomography scan of brain. Anatomic relationships of high convexity-parasagittal gyri and sulci that form the base for signs used for localization of central sulcus were assessed. The frequency of visualization of each sign was noted. RESULTS: Sigmoid shape "hook" of central sulcus (87%) was the most frequent sign followed by pars bracket sign (85%), thin postcentral gyrus sign (84.5%) and superior frontal sulcus-precentral sulcus sign (81.3%). Most of the central sulcus signs showed significant positive correlations with the increasing age. Pars bracket sign was the second most common sign and did not show correlation with age. CONCLUSIONS: In the absence of anatomic distortion, computed tomography anatomic techniques usually allow identification of the central sulcus on axial section with most useful sign being the sigmoid shape "hook" sign. Application of these signs in combination rather than in isolation helps to identify with near certainty the location of the central sulcus in axial plane.

The Central Sulcus of the Insula: A Highly Reliable Radiographic Landmark for Identification of the Rolandic Sulcus.

BACKGROUND: Anatomic studies have suggested that the central insular sulcus (CIS) runs in line with the Rolandic sulcus (RS). The radiographic relationship between the RS and CIS has not been systematically studied. This study aims to evaluate the applicability of using the CIS as a radiologic landmark to identify the RS. METHODS: We retrospectively reviewed 100 consecutive normal magnetic resonance imaging (MRI) scans (200 hemispheres) performed at a single institution. MRI scans with any intracranial pathology or finding were excluded. Sagittal and axial fluid-attenuated inversion recovery sequences were used in this study. Two evaluators independently evaluated the relationship of the CIS and RS in all MRI scans. A predefined 3-step method was then used to identify the CIS, RS, and hand motor area in sagittal and axial images. RESULTS: The CIS was found to be correlated with the RS in 191 hemispheres (95.5%). In the remaining 9 hemispheres, the postcentral sulcus represented the most correlated sulcus with the CIS (7 hemispheres). The interrater agreement was 0.673 (P < 0.05), indicating a substantial agreement. The hand motor area was identified in the same section as the CIS in 175 hemispheres (87.5%). CONCLUSIONS: The CIS is a highly reliable radiographic landmark for the identification of the RS. The hand motor area can also be identified reliably using this method.

Anatomical and neurophysiological localization of the leg motor area at the medial central sulcus.

OBJECTIVE: The exact location of the leg motor area is still in debate due to the lack of landmarks such as 'precentral knob' in the medial cortex. This study tried to identify the leg motor area based on intraoperative neurophysiological data and neuroimaging techniques. METHODS: Intraoperative data of somatosensory evoked potential (SEP) elicited by tibial nerve stimulation and motor evoked potential (MEP) of the leg muscles induced by direct cortical stimulation were recorded using subdural electrodes placed in the medial cortex. We displayed the neurophysiological data on the individual MR images and the MNI52. RESULTS: Definite N40-P40 phase reversal was observed with the shallow grooves in the medial cortex in 5 cases. Leg MEP was successfully obtained in all 12 cases preserving the leg motor function. Superimposed SEP and leg MEP data on the MNI152 indicated the leg motor area was predominantly located in the posterior two-thirds between the vertical lines passing through the anterior commissure and the posterior commissure (VCP). CONCLUSIONS: Our study revealed the location of the leg motor area and the presence of the 'medial central sulcus' in the medial cortex. SIGNIFICANCE: The VCP can be useful landmark to identify the sensorimotor border in the medial cortex.

Reduced Sulcal Depth in Central Sulcus of Major Depressive Disorder.

Major depressive disorder (MDD) is one of the most common psychiatric disorders, and present various symptoms such as the dysregulation of mood, cognition, and behavior. The purpose of the present study was to investigate the morphometric change in MDD patients by voxel-based morphometry (VBM) and sulcal depth analyses. Forty-six MDD patients (mean age, SD; 36.07±14.34), and 23 age- and sex-matched normal controls (NML) (mean age, SD; 36.78±14.42) were included. Coronal 3D T1 magnetic resonance imaging (MRI) was obtained with the resolution of isotropic 1.0 mm. To check morphological changes of brain, T1 MRIs were objectively processed by VBM and sulcal depth methods. In sulcal depth analysis, depressed patients showed reduced sulcal depth in the areas of left posterior ramus of the lateral sulcus, superior frontal sulcus, supramarginal gyrus, central sulcus (Rolando's fissure), and Heschl's gyrus. And right posterior ramus of the lateral sulcus, temporal plane of the superior temporal gyrus, anterior transverse collateral sulcus, and central sulcus (Rolando's fissure) were also reduced compared to NML. But, VBM analyses did not showed significant finding. Reduced sulcal depth in the motor and emotion related areas were found in patients with MDD. Especially reduced sulcal depth in bilateral central sulci which are connecting between primary motor cortex and primary sensory cortex seems to be related with social and physical anhedonia in MDD.

Automated intraoperative central sulcus localization and somatotopic mapping using median nerve stimulation.

Objective. Accurate identification of functional cortical regions is essential in neurological resection. The central sulcus (CS) is an important landmark that delineates functional cortical regions. Median nerve stimulation (MNS) is a standard procedure to identify the position of the CS intraoperatively. In this paper, we introduce an automated procedure that uses MNS to rapidly localize the CS and create functional somatotopic maps.Approach. We recorded electrocorticographic signals from 13 patients who underwent MNS in the course of an awake craniotomy. We analyzed these signals to develop an automated procedure that determines the location of the CS and that also produces functional somatotopic maps.Main results. The comparison between our automated method and visual inspection performed by the neurosurgeon shows that our procedure has a high sensitivity (89%) in identifying the CS. Further, we found substantial concordance between the functional somatotopic maps generated by our method and passive functional mapping (92% sensitivity).Significance. Our automated MNS-based method can rapidly localize the CS and create functional somatotopic maps without imposing additional burden on the clinical procedure. With additional development and validation, our method may lead to a diagnostic tool that guides neurosurgeons and reduces postoperative morbidity in patients undergoing resective brain surgery.

Anatomy of the Cerebral Cortex, Lobes, and Cerebellum.

Strong foundational knowledge of the anatomy of the cerebral cortex, lobes, and cerebellum is key to guide the search for potential lesions based on clinical presentation and known focal neurologic deficits. This article provides an introduction and overview of cerebral cortical anatomy, including the key sulci that divide the 4 lobes of the cerebral cortex, as well as the major gyral and sulcal landmarks within each lobe. The organization of the cerebellum and its major anatomic constituents are also described. Commonly encountered anatomic variants and asymmetries in cerebral cortical anatomy are presented and discussed.

Morphological and functional variability in central and subcentral motor cortex of the human brain.

There is a long-established link between anatomy and function in the somatomotor system in the mammalian cerebral cortex. The morphology of the central sulcus is predictive of the location of functional activation peaks relating to movement of different effectors in individuals. By contrast, morphological variation in the subcentral region and its relationship to function is, as yet, unknown. Investigating the subcentral region is particularly important in the context of speech, since control of the larynx during human speech production is related to activity in this region. Here, we examined the relationship between morphology in the central and subcentral region and the location of functional activity during movement of the hand, lips, tongue, and larynx at the individual participant level. We provide a systematic description of the sulcal patterns of the subcentral and adjacent opercular cortex, including the inter-individual variability in sulcal morphology. We show that, in the majority of participants, the anterior subcentral sulcus is not continuous, but consists of two distinct segments. A robust relationship between morphology of the central and subcentral sulcal segments and movement of different effectors is demonstrated. Inter-individual variability of underlying anatomy might thus explain previous inconsistent findings, in particular regarding the ventral larynx area in subcentral cortex. A surface registration based on sulcal labels indicated that such anatomical information can improve the alignment of functional data for group studies.

U-shape short-range extrinsic connectivity organisation around the human central sulcus.

The central sulcus is probably one of the most studied folds in the human brain, owing to its clear relationship with primary sensory-motor functional areas. However, due to the difficulty of estimating the trajectories of the U-shape fibres from diffusion MRI, the short structural connectivity of this sulcus remains relatively unknown. In this context, we studied the spatial organization of these U-shape fibres along the central sulcus. Based on high quality diffusion MRI data of 100 right-handed subjects and state-of-the-art pre-processing pipeline, we first define a connectivity space that provides a comprehensive and continuous description of the short-range anatomical connectivity around the central sulcus at both the individual and group levels. We then infer the presence of five major U-shape fibre bundles at the group level in both hemispheres by applying unsupervised clustering in the connectivity space. We propose a quantitative investigation of their position and number of streamlines as a function of hemisphere, sex and functional scores such as handedness and manual dexterity. Main findings of this study are twofold: a description of U-shape short-range connectivity along the central sulcus at group level and the evidence of a significant relationship between the position of three hand related U-shape fibre bundles and the handedness score of subjects.

Developmental changes of the central sulcus morphology in young children.

The human brain grows rapidly in early childhood, reaching 95% of its final volume by age 6. Understanding brain growth in childhood is important both to answer neuroscience questions about anatomical changes in development, and as a comparison metric for neurological disorders. Metrics for neuroanatomical development including cortical measures pertaining to the sulci can be instrumental in early diagnosis, monitoring, and intervention for neurological diseases. In this paper, we examine the development of the central sulcus in children aged 12-60 months from structural magnetic resonance images. The central sulcus is one of the earliest sulci to develop at the fetal stage and is implicated in diseases such as Attention Deficit Hyperactive Disorder and Williams syndrome. We investigate the relationship between the changes in the depth of the central sulcus with respect to age. In our results, we observed a pattern of depth present early on, that had been previously observed in adults. Results also reveal the presence of a rightward depth asymmetry at 12 months of age at a location related to orofacial movements. That asymmetry disappears gradually, mostly between 12 and 24 months, and we suggest that it is related to the development of language skills.