Brain Mapping Techniques Research Articles

Functional near-infrared spectroscopy for intraoperative brain mapping.

.Functional near-infrared spectroscopy (fNIRS) is a relatively new seizure-free technique and its value for intraoperative brain mapping is unknown. We examine the feasibility of fNIRS for intraoperative functional brain mapping. A density fNIRS probe specially designed for intraoperative use was used to map brain function in adult patients undergoing awake brain surgery and performing motor and/or language tasks. The ability of fNIRS for functional mapping was compared with direct cortical stimulation (DCS) and regression was used to determine if mean blood pressure (MBP) and blood hemoglobin influenced fNIRS measurements. Eighteen patients underwent awake craniotomy and performed 19 language- and 17 motor-related tasks. fNIRS mapping was highly correlated with DCS for 10 language- and 7 motor-related tasks. fNIRS was able to detect functional language () and motor areas (). Compared to DCS, fNIRS was less accurate in determining both functional language (at least 22.64%, ) and motor areas (at least 32.74%, ). Higher MBP and blood hemoglobin were associated with better fNIRS results ( and 0.007, respectively). No seizures or other complications occurred during fNIRS measurement. fNIRS is a promising seizure-free technique for intraoperative brain mapping. The accuracy of current technology needs further development for clinical use.

Neural bases of self- and object-motion in a naturalistic vision.

To plan movements toward objects our brain must recognize whether retinal displacement is due to self‐motion and/or to object‐motion. Here, we aimed to test whether motion areas are able to segregate these types of motion. We combined an event‐related functional magnetic resonance imaging experiment, brain mapping techniques, and wide‐field stimulation to study the responsivity of motion‐sensitive areas to pure and combined self‐ and object‐motion conditions during virtual movies of a train running within a realistic landscape. We observed a selective response in MT to the pure object‐motion condition, and in medial (PEc, pCi, CSv, and CMA) and lateral (PIC and LOR) areas to the pure self‐motion condition. Some other regions (like V6) responded more to complex visual stimulation where both object‐ and self‐motion were present. Among all, we found that some motion regions (V3A, LOR, MT, V6, and IPSmot) could extract object‐motion information from the overall motion, recognizing the real movement of the train even when the images remain still (on the screen), or moved, because of self‐movements. We propose that these motion areas might be good candidates for the “flow parsing mechanism,” that is the capability to extract object‐motion information from retinal motion signals by subtracting out the optic flow components.

Effects of sonication parameters on transcranial focused ultrasound brain stimulation in an ovine model.

Low-intensity focused ultrasound (FUS) has significant potential as a non-invasive brain stimulation modality and novel technique for functional brain mapping, particularly with its advantage of greater spatial selectivity and depth penetration compared to existing non-invasive brain stimulation techniques. As previous studies, primarily carried out in small animals, have demonstrated that sonication parameters affect the stimulation efficiency, further investigation in large animals is necessary to translate this technique into clinical practice. In the present study, we examined the effects of sonication parameters on the transient modification of excitability of cortical and thalamic areas in an ovine model. Guided by anatomical and functional neuroimaging data specific to each animal, 250 kHz FUS was transcranially applied to the primary sensorimotor area associated with the right hind limb and its thalamic projection in sheep (n = 10) across multiple sessions using various combinations of sonication parameters. The degree of effect from FUS was assessed through electrophysiological responses, through analysis of electromyogram and electroencephalographic somatosensory evoked potentials for evaluation of excitatory and suppressive effects, respectively. We found that the modulatory effects were transient and reversible, with specific sonication parameters outperforming others in modulating regional brain activity. Magnetic resonance imaging and histological analysis conducted at different time points after the final sonication session, as well as behavioral observations, showed that repeated exposure to FUS did not damage the underlying brain tissue. Our results suggest that FUS-mediated, non-invasive, region-specific bimodal neuromodulation can be safely achieved in an ovine model, indicating its potential for translation into human studies.

A Comprehensive Review of the Brain Mapping Technique

The Brain mapping technique is the branch of Neuroscience which deals in the spatial representation of the Human Brain. It is an ultra modern Biological Computational technique which makes use of various constituent areas like Computational biology, Engineering principles, Resonance imaging for unveiling the functioning & complex structures of the Brain. It involves study of the structural anatomy of the Brain & the brain sensory nerves by using the inter-operative, noninvasive Bio Medical & the Cellular biology with the involvement & use of modern Computational Techniques like 4-D Imaging, Cognitive Sciences, Fuzzy Logic etc. It reveals the physiological & anatomical changes that occur in the Brain due to the passage of time or due to some mental illness caused. The ongoing research in this area has enhanced the understanding of various Brain learning deficiencies. The research in Brain mapping technique has shown that learning of a skill changes the Brain‘s composition structure & these changes revert when practice of the skill ceases. So, In this paper we have carried out a survey based on the work performed by various researchers in the area of the Brain mapping technique. After conducting the survey, we can conclude that Human brain mapping has helped the Neurologists to enhance their understanding & improving their knowledge base of the Human Brain in improving the learning capabilities of the Homo sapiens.

History of awake mapping and speech and language localization: from modules to networks.

Lesion-symptom correlations shaped the early understanding of cortical localization. The classic Broca-Wernicke model of cortical speech and language organization underwent a paradigm shift in large part due to advances in brain mapping techniques. This initially started by demonstrating that the cortex was excitable. Later, advancements in neuroanesthesia led to awake surgery for epilepsy focus and tumor resection, providing neurosurgeons with a means of studying cortical and subcortical pathways to understand neural architecture and obtain maximal resection while avoiding so-called critical structures. The aim of this historical review is to highlight the essential role of direct electrical stimulation and cortical-subcortical mapping and the advancements it has made to our understanding of speech and language cortical organization. Specifically, using cortical and subcortical mapping, neurosurgeons shifted from a localist view in which the brain is composed of rigid functional modules to one of dynamic and integrative large-scale networks consisting of interconnected cortical subregions.

Transopercular Resection of IDH–Mutated Insular Glioma: A Critical Appraisal of an Initial Experience

Recent data suggest a favorable benefit/risk ratio for insular glioma surgery. However, it remains unknown if this is also applicable in the learning period of this expertise. Moreover, little is known about the neuropsychological outcomes after resection of insular glioma. To report an initial experience of isocitrate dehydrogenase (IDH)-mutated insular glioma resection and to contribute to our knowledge of neuropsychological outcomes after insular glioma resection. A consecutive series of 12 patients operated on for an IDH-mutated insular glioma was retrospectively reviewed. Surgery was performed through a transopercular approach. In 10 of the 12 patients, brain mapping with electric stimulation in an awake patient guided the resection. The extent of resection was assessed by volumetric measures of postoperative fluid-attenuated inversion recovery magnetic resonance imaging. Areas of postoperative ischemia were detected by diffusion imaging. Neurologic, neuropsychological, and professional outcomes were retrieved from medical files. The median extent of resection was 94% (range, 80%-100%). None of the patients had permanent speech or motor deficits. Areas of ischemia were observed in 75% of patients. Neuropsychological evaluations showed slight deterioration regarding lexical abilities and verbal memory in patients with left-sided tumors. Patients' performances in cognitive flexibility also commonly declined, regardless of the tumor side. Eight of the 9 patients working at the time of the surgery were able to resume their professional activity. Resecting insular glioma under brain mapping techniques is a safe option, even during the learning period. Patients should be informed about the risk of mild deterioration of lexical abilities and cognitive flexibility.

Investigational and Therapeutic Applications of Transcranial Magnetic Stimulation in Schizophrenia.

This current review summarizes the investigational and therapeutic applications of transcranial magnetic stimulation (TMS) in schizophrenia. Fairly consistent findings of an impaired cortical excitation-inhibition balance, cortical plasticity, and motor resonance have been reported in schizophrenia. Cortical connectivity impairments have also been demonstrated in motor and prefrontal brain regions. In terms of treatment, the best support is for 1-Hz TMS to the left temporoparietal cortex for the short-term treatment of persistent auditory hallucinations. High-frequency TMS to the left prefrontal cortex improves negative and cognitive symptoms, but with inconsistent and small effects. TMS combined with diverse brain mapping techniques and clinical evaluation can unravel critical brain-behavior relationships relevant to schizophrenia. These provide critical support to the conceptualization of schizophrenia as a connectopathy with anomalous cortical plasticity. Adaptive modulation of these aberrant brain networks in a neuroscience-informed manner drives short-term therapeutic gains in difficult-to-treat symptoms of schizophrenia.

A review of neurophysiological and genetic correlates of emotional intelligence

The article is an overview of modern studies of brain organization and genetic correlates of emotional intelligence. Emotional intelligence is becoming the subject of more and more attentive study of psychologists due to the fact that it influences the mental development of humans, plays an important role in many professions, and its impairment is a marker of some disorders. Nevertheless, the brain organization and genetic correlates of emotional intelligence have not been studied enough – first studies appeared only in the early 2000s. A review of the literature on the enceph-alographic showed that in rest, people with higher emotional intelligence show greater excitation of the left anterior regions of the brain. When per-ceiving affective stimuli, participants with high emotional intelligence show stronger synchronization of some EEG rhythms. Brain mapping technique made it possible to identify the areas of the brain involved in activities related to emotional intelligence. In regard to genetic correlates of emotional intelligence, some genes of neurotransmitter systems have been associated to this trait: the catechol-O-methyltransferase gene COMT, the dopamine DRD2 receptor gene, the serotonin receptor gene HTR2A, and the BDNF brain neurotrophic factor gene.

Anatomo-functional characterisation of the human “hand-knob”: A direct electrophysiological study

The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the ‘hand-knob’ and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an internal subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control.

Frontal lobectomy: From an historical view to new concepts

Almost a century ago, neurosurgeons performed the first surgical disconnections of the frontal lobe (leucotomies) in psychiatric diseases, and then frontal lobectomies (FL), mainly in epilepsy. Since these initial resections, which induced a high rate of neurologic consequences, FL were conceptually associated to a combination of cognitive, emotional and behavioral symptoms known under the term of “frontal syndrome”. However, because of a recent paradigmatic shift from a localizationist to a connectomal theory of neural processing, and thanks to advances in brain mapping techniques, the traditional concept of irrevocable frontal syndrome generated by FL has been called into question [1] . Indeed, in the more recent field of neurooncological surgery, massive FL have been achieved up to individual eloquent networks identified by intraoperative direct electrical stimulation both at cortical and subcortical levels [2] . Using this philosophy of functional mapping-based resection, the existence of a huge potential of cortical plasticity has been evidenced, allowing a preservation of neurologic and neurocognitive status, including executive functions, mentalizing and metacognition, following unilateral or even bilateral FL [3] . Such a functional compensation is possible owing to the preservation of the white matter tracts that represent the limitation of neuroplasticity [4] . In fact, to prevent the occurrence of a “frontal syndrome”, which is most of the time the consequence of a dysconnectionism syndrome, the goal of FL is to surgically spare the intra-lobar connectivity (e.g. the frontal aslant tract), the inter-lobar long-range association fibers (e.g. the superior longitudinal fasciculus, arcuate fasciculus and inferior fronto-occipital fasciculus) as well as the projection fibers (e.g. the fronto-striatal tract) [5] . This improved knowledge of the functional connectome enables to significantly increase the overall survival while preserving the quality of life of brain tumor patients [6] . In addition, these new insights into cerebral processing can be applied to other fields of neurosurgery, such as brain-computer interface, to neurology and neurorehabilitation, by elaborating specific programs of cognitive remediation, and to basic neurosciences by proposing new behavioral models challenging the classical localist dogma.

Zur zerebralen Organisation von Sprach

The article is devoted to the cerebral organisation of language. This work is intended as a state-of-the-art paper describing current research and theory in some subfields of cognitive neuroscience that may be of importance for the glottodidactics. Part 1 focuses on the issue of lateralization of language. Part 2 provides information on evaluation procedures in brain and points out that language, cognition and emotion can't be viewed as separate elements of mental processing. An attempt has been made to elucidate the role of epigenetic determinations in learning process. In part 3 experimental aspects of neurolinguistics are emphasized, such as aphasia research, advanced brain mapping techniques as essential steps toward better understanding the neural correlates of language functions, and a review how event-related potentials (ERPs) have been used to reflect semantic and syntactic processing in normal adults and children.

Preoperative surgical planning of glioma: limitations and reliability of fMRI and DTI tractography.

Brain mapping techniques (intraoperative neurophysiology and neuropsychology) represent the gold standard in glioma surgery, and particularly in glioma resection. Since the introduction of MRI in the clinical practice, several advanced applications have been developed, like functional MRI (fMRI) and diffusion imaging-based tractography (DTI), which both have an application in glioma surgery. fMRI allows to identify cortical areas related to a specific function, DTI allows to reconstruct a model of the sub-cortical connectivity. This paper describes the clinical application of fMRI and DTI, enlightening sensitivity and specificity in comparison to gold standard and underlining their limitations in surgical decision making.

An Introductory Guide to Organizational Neuroscience

The time is ripe for a renewed and interdisciplinary approach to organizational research that incorporates neuroscientific techniques. Like all methods, they have methodological, analytical, and interpretational limitations; however, the potential gains from using these techniques are far more considerable. We have therefore assembled a succinct yet authoritative collection of articles on the topic of neuroscience in organizational research, to serve as a solid introduction to the methods of neuroscience and what they can accomplish. The special topic is organized into two parts. The first includes a set of accessible reviews of the palette of brain imaging, mapping, and stimulation techniques (fMRI, fNIRS, EEG, MEG, and NIBS) as well as examples of the application of neuroscience methods to various disciplines including economics, marketing, finance, organizational behavior, neuroethology, as well an integrative translational critique on a variety of applications. The second is a collection of articles resulting from a competitive call for submissions that cover various neuroscience topics but also address important methodological and philosophical issues. The articles lay out a roadmap for the effective integration of neuroscientific methods into organizational research.

Brain Bar Codes.

The article discusses research on a brain-mapping technique to trace neuron connections by researchers at Cold Spring Harbor Laboratory published in the April 2018 issue of the journal "Nature."

Treatment of cavernous malformations in supratentorial eloquent areas: experience after 10 years of patient-tailored surgical protocol

Eloquent area surgery has become safer with the development of intraoperative neurophysiological monitoring and brain mapping techniques. However, the usefulness of intraoperative electric brain stimulation techniques applied to the management and surgical treatment of cavernous malformations in supratentorial eloquent areas is still not proven. With this study, we aim to describe our experience with the use of a tailored functional approach to treat cavernous malformations in supratentorial eloquent areas. Twenty patients harboring cavernous malformations located in supratentorial eloquent areas were surgically treated. Individualized functional approach, using intraoperative brain mapping and/or neurophysiological monitoring, was utilized in each case. Eleven patients underwent surgery under awake conditions; meanwhile, nine patients underwent asleep surgery. Total resection was achieved in 19 cases (95%). In one patient, the resection was not possible due to high motor functional parenchyma surrounding the lesion tested by direct cortical stimulation. Ten (50%) patients presented transient neurological worsening. All of them achieved total neurological recovery within the first year of follow-up. Among the patients who presented seizures, 85% achieved seizure-free status during follow-up. No major complications occurred. Intraoperative electric brain stimulation techniques applied by a trained multidisciplinary team provide a valuable aid for the treatment of certain cavernous malformations. Our results suggest that tailored functional approach could help surgeons in adapting surgical strategies to prevent patients' permanent neurological damage.

Frequency of gross total resection in intra-axial brain tumors with help of neuronavigation

Background: Neuronavigation has become a ubiquitous tool in the surgical management of brain tumors. Neuronavigation is most useful as an adjunct to other brain-mapping techniques such as awake mapping and electrocorticography in the resection of lesions within eloquent motor and language areas. Neuronavigation is also commonly used in skull base tumors, especially for planning an operative trajectory in regions containing vital neurovascular structures and may be used for cerebrovascular surgery. The current study was planned to determine the frequency of gross total resection in intra-axial brain tumors with the help of neuronavigation.Methods: This cross-sectional study was carried out in the Department of Neurosurgery, Nishtar Medical College and Hospital, Multan, from September 2014 to March 2015. After approval from institutional ethical committee, seventy-seven patients fulfilling the inclusion criteria were selected from the patient admitted in the Neurosurgical Department through the Out-Patient Department and patients referred from other departments. After thorough counseling with the patient and his/her relatives, informed consent for procedure was taken.Results: Total 78 patients were included in the study. Out of these 78 (100%), 41 (52.6%) were male and 37 (47.4%) were female. As concern to the outcome variable (gross total resection), out of 78 (100%), in 61 (78.2%) patients gross total resection was present. On cross tabulation it was further clarified that in male patients’ gross total resection present in 32 patients and absent in 9 patients. Similarly, in female patients gross total resection present in 29 patients and absent in 8 patients. P value was 0.747.Conclusions: Conclusion of present study is that neuronavigation is a useful technique in for better gross total resection of intra axial brain tumors.

Are We Ready for Real-world Neuroscience?

Real-world environments are typically dynamic, complex, and multisensory in nature and require the support of top-down attention and memory mechanisms for us to be able to drive a car, make a shopping list, or pour a cup of coffee. Fundamental principles of perception and functional brain organization have been established by research utilizing well-controlled but simplified paradigms with basic stimuli. The last 30 years ushered a revolution in computational power, brain mapping, and signal processing techniques. Drawing on those theoretical and methodological advances, over the years, research has departed more and more from traditional, rigorous, and well-understood paradigms to directly investigate cognitive functions and their underlying brain mechanisms in real-world environments. These investigations typically address the role of one or, more recently, multiple attributes of real-world environments. Fundamental assumptions about perception, attention, or brain functional organization have been challenged-by studies adapting the traditional paradigms to emulate, for example, the multisensory nature or varying relevance of stimulation or dynamically changing task demands. Here, we present the state of the field within the emerging heterogeneous domain of real-world neuroscience. To be precise, the aim of this Special Focus is to bring together a variety of the emerging "real-world neuroscientific" approaches. These approaches differ in their principal aims, assumptions, or even definitions of "real-world neuroscience" research. Here, we showcase the commonalities and distinctive features of the different "real-world neuroscience" approaches. To do so, four early-career researchers and the speakers of the Cognitive Neuroscience Society 2017 Meeting symposium under the same title answer questions pertaining to the added value of such approaches in bringing us closer to accurate models of functional brain organization and cognitive functions.

Endoscopic Approach of the Insula Through the Anterior Middle Temporal Gyrus: A Feasibility Study in the Laboratory.

Insular glioma surgery still represents a challenge. Nonetheless, advances in microsurgical anatomy and brain mapping techniques have allowed an increase in the extent of resection with acceptable morbidity rates. Transsylvian and transcortical approaches constitute the main surgical corridors, the latter providing considerable advantages and a high degree of reliability. Nevertheless, both surgical corridors yield remarkable difficulties in reaching the most posterior insular region. To study the feasibility of an endoscopic transtemporal approach in brain specimens, with the aim to provide a suitable access for posterior insular region. Four postmortem human hemispheres, embalmed using Klingler's technique, were dissected by means of a 30° rigid endoscope. The specimens underwent magnetic resonance imaging scans and, using the neuronavigation system, we were able to design a safe cortical window and an optimized endoscopic trajectory for the posterior insular dissection. Insular dissection was led subpially through a small 2-cm cortical access, located in the anterior part of the middle temporal gyrus. During the posterior insula dissection, the endoscope allowed for optimized surgical view all along the long gyri, up to the posterior insular point. Anterior insular dissection was accomplished with more difficulties, as the endoscopic trajectory was not aligned to the axis of the short gyri. This new surgical approach provides a favorable transcortical access to reach the most posterior insular portion. It seems to be a promising tool, in combination with intraoperative functional brain mapping, to further improve extent of resection rates in insular glioma surgery.

Assessment of the praxis circuit in glioma surgery to reduce the incidence of postoperative and long-term apraxia: a new intraoperative test.

OBJECTIVEApraxia is a cognitive-motor deficit affecting the execution of skilled movements, termed praxis gestures, in the absence of primary sensory or motor disorders. In patients affected by stroke, apraxia is associated with lesions of the lateral parietofrontal stream, connecting the posterior parietal areas with the ventrolateral premotor area and subserving sensory-motor integration for the hand movements. In the neurosurgical literature to date, there are few reports regarding the incidence of apraxia after glioma surgery. A retrospective analysis of patients who harbored a glioma around the central sulcus and close to the parietofrontal circuits in depth showed a high incidence of long-term postoperative hand apraxia, impairing the patients' quality of life. To avoid the occurrence of postoperative apraxia, the authors sought to develop an innovative intraoperative hand manipulation task (HMt) that can be used in association with the brain mapping technique to identify and preserve the cortical and subcortical structures belonging to the praxis network.METHODSThe intraoperative efficacy of the HMt was investigated by comparing the incidence of postoperative ideomotor apraxia between patients undergoing mapping with (n = 79) and without (n = 41) the HMt. Patient groups were balanced for all demographic and clinical features.RESULTSIn patients with lesions in the dominant hemisphere, the HMt dramatically reduced the incidence of apraxia, with a higher sensitivity for the ideomotor than for the constructional abilities; patients with lesions in the nondominant hemisphere benefitted from the HMt for both ideomotor and constructional abilities. The administration of the test did not reduce the extent of resection.CONCLUSIONSThe HMt is a safe and feasible intraoperative tool that allowed surgeons to prevent the occurrence of long-term hand apraxia while attaining resection goals for the surgical treatment of glioma.

Double dissociation of structure-function relationships in memory and fluid intelligence observed with magnetic resonance elastography

Brain tissue mechanical properties, measured in vivo with magnetic resonance elastography (MRE), have proven to be sensitive metrics of neural tissue integrity. Recently, our group has reported on the positive relationship between viscoelasticity of the hippocampus and performance on a relational memory task in healthy young adults, which highlighted the potential of sensitive MRE measures for studying brain health and its relation to cognitive function; however, structure-function relationships outside of the hippocampus have not yet been explored. In this study, we examined the relationships between viscoelasticity of both the hippocampus and the orbitofrontal cortex and performance on behavioral assessments of relational memory and fluid intelligence. In a sample of healthy, young adults (N = 53), there was a significant, positive relationship between orbitofrontal cortex viscoelasticity and fluid intelligence performance (r = 0.42; p = .002). This finding is consistent with the previously reported relationship between hippocampal viscoelasticity and relational memory performance (r = 0.41; p = .002). Further, a significant double dissociation between the orbitofrontal-fluid intelligence relationship and the hippocampal-relational memory relationship was observed. These data support the specificity of regional brain MRE measures in support of separable cognitive functions. This report of a structure-function relationship observed with MRE beyond the hippocampus suggests a future role for MRE as a sensitive neuroimaging technique for brain mapping.