scholarly journals Variance in cortical depth across the brain surface

2020 ◽  
Author(s):  
Nick J. Davis
Keyword(s):  
Grey Matter ◽  
Brain Area ◽  
Cortical Surface ◽  
Brain Areas ◽  
Brain Images ◽  
Non Invasive ◽  
Brain Surface ◽  
Key Factor ◽  
Anatomical Mri ◽  
The Brain

AbstractThe distance between the surface of the scalp and the surface of the grey matter of the brain is a key factor in determining the effective dose of non-invasive brain stimulation for an individual person. The highly folded nature of the cortical surface means that the depth of a particular brain area is likely to vary between individuals. The question addressed here is: what is the variability of this measure of cortical depth? 94 anatomical MRI images were taken from the OASIS database. For each image, the minimum distance from each point in the grey matter to the scalp surface was determined. Transforming these estimates into standard space meant that the coefficient of variation could be determined across the sample. The results indicated that depth variability is high across the cortical surface, even when taking sulcal depth into account. This was true even for the primary visual and motor areas, which are often used in setting TMS dosage. The correlation of the depth of these areas and the depth of other brain areas was low. The results suggest that dose-setting of TMS based on visual or evoked potentials may offer poor reliability, and that individual brain images should be used when targeting non-primary brain areas.

scholarly journals A Simple Method to Avoid Brain Shift during Neuronavigation: Technical Note

2020 ◽  
Author(s):  
Jair Leopoldo Raso
Keyword(s):  
Dura Mater ◽  
Brain Area ◽  
Conventional Technique ◽  
Technical Note ◽  
Cortical Surface ◽  
Brain Shift ◽  
Simple Method ◽  
Cortex Area ◽  
Neuronavigation System ◽  
The Brain

Abstract Introduction The precise identification of anatomical structures and lesions in the brain is the main objective of neuronavigation systems. Brain shift, displacement of the brain after opening the cisterns and draining cerebrospinal fluid, is one of the limitations of such systems. Objective To describe a simple method to avoid brain shift in craniotomies for subcortical lesions. Method We used the surgical technique hereby described in five patients with subcortical neoplasms. We performed the neuronavigation-guided craniotomies with the conventional technique. After opening the dura and exposing the cortical surface, we placed two or three arachnoid anchoring sutures to the dura mater, close to the edges of the exposed cortical surface. We placed these anchoring sutures under microscopy, using a 6–0 mononylon wire. With this technique, the cortex surface was kept close to the dura mater, minimizing its displacement during the approach to the subcortical lesion. In these five cases we operated, the cortical surface remained close to the dura, anchored by the arachnoid sutures. All the lesions were located with a good correlation between the handpiece tip inserted in the desired brain area and the display on the navigation system. Conclusion Arachnoid anchoring sutures to the dura mater on the edges of the cortex area exposed by craniotomy constitute a simple method to minimize brain displacement (brain-shift) in craniotomies for subcortical injuries, optimizing the use of the neuronavigation system.

scholarly journals Muscular Movements in Man, and their Evolution in the Infant: a Study of Movement in Man, and its Evolution, together with Inferences as to the Properties of Nerve-Centres and their Modes of Action in expressing Thought

1889 ◽  
Vol 35 (149) ◽  
pp. 23-44 ◽  
Author(s):  
Francis Warner
Keyword(s):  
Brain Area ◽  
Muscular Contraction ◽  
The Body ◽  
Brain Areas ◽  
Modes Of Action ◽  
Central Nerve System ◽  
Nerve System ◽  
The Brain ◽  
Compound Series ◽  
Stimulation Of

(1) Movement in mau has long been a subject of profitable study. Visible movement in the body is produced by muscular contraction following upon stimulation of the muscles by efferent currents passing from the central nerve-system. Modern physiological experiments have demonstrated that when a special brain-area discharges nerve-currents, these are followed by certain visible movements or contraction of certain muscles corresponding. So exact are such reactions, as obtained by experiment upon the brain-areas, that movements similar to those produced by experimental excitation of a certain brain-area may be taken as evidence of action in that area, or as commencing in discharge from that area (see Reinforcement of Movements, 35; Compound Series of Movements, 34).

scholarly journals Shocking the brain to regain motor function : a non-invasive therapy for stroke patients

2018 ◽  
Vol 1 ◽  
pp. 20-22
Author(s):  
Michael Min Wah Leung
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Invasive Technique ◽  
Stroke Patients ◽  
Interhemispheric Inhibition ◽  
Brain Areas ◽  
Sensory Deficits ◽  
Direct Current Stimulation ◽  
Non Invasive ◽  
The Brain

Invasive treatments and its associated risks are important factors of concern when the conditions are affecting the nervous system. Transcranial direct current stimulation (tDCS) is a non-invasive technique that stimulates brain areas through the scalp and has excitatory or inhibitory neuromodulatory effects. In the context of stroke patients, recovery is often impaired from the increased inhibition of the damaged area from the unaffected hemisphere. Fujimoto et al. uses dual-hemisphere transcranial direct current stimulation to address this interhemispheric inhibition and demonstrates that stroke patients were able to periodically restore sensory deficits. 

A Systematic Review of Clustering and Classifier Techniques for Brain Tumor Segmentation in MRI Images

2021 ◽  
Vol 11 (2) ◽  
pp. 46-57
Author(s):  
Veeresh Ashok Mulimani ◽  
Sanjeev S. Sannakki ◽  
Vijay S. Rajpurohit
Keyword(s):  
Systematic Review ◽  
Brain Tumor ◽  
Clustering Algorithms ◽  
Tumor Segmentation ◽  
Brain Tumor Segmentation ◽  
Brain Images ◽  
Non Invasive ◽  
Tissue Contrast ◽  
High Resolution Images ◽  
The Brain

MRI technique is widely used in the field of medicine because of its high spatial resolution, non-invasive characteristics, and soft tissue contrast. In this review article, a systematic study has been conducted to analyze the performance and issues of various techniques for brain tumor segmentation. Latest research on BTS in MRI with the higher resolution is utilized for the systematic review. The high-resolution images increase execution time of the classification, and accuracy is the other problem in BTS. Still, there is some research lacking in accuracy on the brain segmentation. Few researchers carried out the classification of different kinds of tissues in the brain images and also on the prediction on growth of tumor. Each method has specific technique to improve the performance of the BTS, and these methods are compared with one another in terms of result. Research comparison helps to understand the proposed method with their achieved results. Clustering algorithms such as K-means and FCM are generally used for segmentation, and GA, ANN, ANFIS, FCNN, SVM are commonly used as classifiers.

scholarly journals Separate Representations of Target and Timing Cue Locations in the Supplementary Eye Fields

2009 ◽  
Vol 101 (1) ◽  
pp. 448-459 ◽  
Author(s):  
Michael Campos ◽  
Boris Breznen ◽  
Richard A. Andersen
Keyword(s):  
Eye Movement ◽  
Brain Area ◽  
Target Position ◽  
Oculomotor System ◽  
Small Population ◽  
Oculomotor Control ◽  
Brain Areas ◽  
Saccade Task ◽  
Supplementary Eye Fields ◽  
The Brain

When different stimuli indicate where and when to make an eye movement, the brain areas involved in oculomotor control must selectively plan an eye movement to the stimulus that encodes the target position and also encode the information available from the timing cue. This could pose a challenge to the oculomotor system since the representation of the timing stimulus location in one brain area might be interpreted by downstream neurons as a competing motor plan. Evidence from diverse sources has suggested that the supplementary eye fields (SEF) play an important role in behavioral timing, so we recorded single-unit activity from SEF to characterize how target and timing cues are encoded in this region. Two monkeys performed a variant of the memory-guided saccade task, in which a timing stimulus was presented at a randomly chosen eccentric location. Many spatially tuned SEF neurons encoded only the location of the target and not the timing stimulus, whereas several other SEF neurons encoded the location of the timing stimulus and not the target. The SEF population therefore encoded the location of each stimulus with largely distinct neuronal subpopulations. For comparison, we recorded a small population of lateral intraparietal (LIP) neurons in the same task. We found that most LIP neurons that encoded the location of the target also encoded the location of the timing stimulus after its presentation, but selectively encoded the intended eye movement plan in advance of saccade initiation. These results suggest that SEF, by conditionally encoding the location of instructional stimuli depending on their meaning, can help identify which movement plan represented in other oculomotor structures, such as LIP, should be selected for the next eye movement.

scholarly journals EEG representing on brain surface using volume rendering

2021 ◽  
Vol 8 (1) ◽  
pp. 10-15
Author(s):  
Dmitrii Klementev ◽  
Vladimir Guzhov ◽  
Wolfram Hardt
Keyword(s):  
Volume Rendering ◽  
Brain Research ◽  
Point Of View ◽  
Resonance Imaging ◽  
Mri Scan ◽  
Non Invasive ◽  
Brain Surface ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain ◽  
Brain Template

Brain research is challenging. One of the standard research methods is electroencephalography (EEG). As a rule, this study is presented in the form of graphs. This article describes an approach in which this data is mapped onto a brain model generated from a magnetic resonance imaging (MRI) scan. This allows you to look at the EEG study from a different point of view. An MRI scan will also allow you to take into account some of the features of the brain. This is an advantage over mapping just to a brain template. This non-invasive system can be implemented to monitor the patient in real-time, for example, during space flight.

scholarly journals Value Shapes Abstraction During Learning

2020 ◽  
Author(s):  
Aurelio Cortese ◽  
Asuka Yamamoto ◽  
Maryam Hashemzadeh ◽  
Pradyumna Sepulveda ◽  
Mitsuo Kawato ◽  
...  
Keyword(s):  
Brain Area ◽  
Computational Modelling ◽  
Choice Data ◽  
Abstract Representations ◽  
Abstract Entities ◽  
Human Volunteers ◽  
Sensory Features ◽  
Key Factor ◽  
Efficient Learning ◽  
The Brain

ABSTRACTAbstractions are critical for flexible behaviours and efficient learning. However, how the brain forgoes the sensory dimension to forge abstract entities remains elusive. Here, in two fMRI experiments, we demonstrate a mechanism of abstraction built upon valuation of task-relevant sensory features. Human volunteers learned hidden association rules between visual features. Computational modelling of participants’ choice data with mixture-of-experts reinforcement learning algorithms revealed that, with learning, emerging high-value abstract representations increasingly guided behaviour. Moreover, the brain area encoding value signals - the ventromedial prefrontal cortex - also prioritized and selected latent task elements, both locally and through its connection to visual cortex. In a second experiment, we used multivoxel neural reinforcement to show how reward-tagging the neural sensory representation of a task’s feature evoked abstraction-based decisions. Our findings redefine the logic of valuation as a goal-dependent, key factor in constructing the abstract representations that govern intelligent behaviour.

Segmentation and clustering in brain MRI imaging

2018 ◽  
Vol 30 (1) ◽  
pp. 31-44 ◽  
Author(s):  
Golrokh Mirzaei ◽  
Hojjat Adeli
Keyword(s):  
Grey Matter ◽  
State Of The Art ◽  
Brain Mri ◽  
Brain Regions ◽  
Mri Imaging ◽  
Resonance Imaging ◽  
Brain Images ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain ◽  
Different Parts

AbstractClustering is a vital task in magnetic resonance imaging (MRI) brain imaging and plays an important role in the reliability of brain disease detection, diagnosis, and effectiveness of the treatment. Clustering is used in processing and analysis of brain images for different tasks, including segmentation of brain regions and tissues (grey matter, white matter, and cerebrospinal fluid) and clustering of the atrophy in different parts of the brain. This paper presents a state-of-the-art review of brain MRI studies that use clustering techniques for different tasks.

scholarly journals Value signals guide abstraction during learning

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Aurelio Cortese ◽  
Asuka Yamamoto ◽  
Maryam Hashemzadeh ◽  
Pradyumna Sepulveda ◽  
Mitsuo Kawato ◽  
...  
Keyword(s):  
Brain Area ◽  
Neural Representation ◽  
Abstract Representations ◽  
Human Volunteers ◽  
Sensory Features ◽  
Key Factor ◽  
Novel Association ◽  
Subjective Confidence ◽  
Task Feature ◽  
The Brain

The human brain excels at constructing and using abstractions, such as rules, or concepts. Here, in two fMRI experiments, we demonstrate a mechanism of abstraction built upon the valuation of sensory features. Human volunteers learned novel association rules based on simple visual features. Reinforcement-learning algorithms revealed that, with learning, high-value abstract representations increasingly guided participant behaviour, resulting in better choices and higher subjective confidence. We also found that the brain area computing value signals - the ventromedial prefrontal cortex - prioritized and selected latent task elements during abstraction, both locally and through its connection to the visual cortex. Such a coding scheme predicts a causal role for valuation. Hence, in a second experiment, we used multivoxel neural reinforcement to test for the causality of feature valuation in the sensory cortex, as a mechanism of abstraction. Tagging the neural representation of a task feature with rewards evoked abstraction-based decisions. Together, these findings provide a novel interpretation of value as a goal-dependent, key factor in forging abstract representations.

scholarly journals A surface metric and software toolbox for EEG electrode grids in the macaque

2020 ◽  
Author(s):  
Fan Li ◽  
Tobias Teichert
Keyword(s):  
Current Approach ◽  
Non Invasive ◽  
Brain Surface ◽  
Manual Intervention ◽  
Planning Optimization ◽  
Efficient Planning ◽  
Eeg Recordings ◽  
The One ◽  
High Level ◽  
The Brain

AbstractBackgroundThe past years have seen increased appreciation of non-invasive extracranial electroencephalographic (EEG) recordings in non-human primates (NHP) as a tool for translational research. In humans, the international 10-20 system or extensions thereof provide standardized electrode positions that enable easy comparison of data between subjects and laboratories. In the NHP, no such generally accepted, standardized placement system is available.New MethodHere we introduce a surface metric and software package (NHP1020) that automates the planning of large, approximately evenly spaced electrode grids on the NHP skull.ResultsThe system is based on one CT and one MRI image and requires the user to specify two intracranial markers. Based on this, the software defines electrode positions on the brain surface using a surface-based spherical metric similar to the one used by the international 10-20 system. The electrode positions are then projected to the surface of the skull. Standardized electrode grids can be shared, imported or defined with few high-level commands.Existing MethodsNHP EEG electrodes are often placed on an individual basis relative to extracranial markers, or relative to underlying neural structures. Both approaches are time-consuming and require manual intervention. Furthermore, the use of extracranial markers in this species may be more problematic than in humans, because cranial muscles and ridges are larger and keep maturing long into adulthood thus potentially affecting electrode positions.ConclusionThe key advantage of the current approach is the automated and objective identification of corresponding electrode positions in different animals. Automation was made possible by the use of a two-dimensional metric on the brain surface which has a simpler, i.e., more convex and sphere-like anatomy than the skull. This enables fast and efficient planning, optimization and calculation of large electrode grids.

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