Talairach coordinates, also known as Talairach space, is a 3-dimensional coordinate system (known as an 'atlas') of the human brain, which is used to map the location of brain structures independent from individual differences in the size and overall shape of the brain. It is still common to use Talairach coordinates in functional brain imaging studies and to target transcranial stimulation of brain regions. [1] However, alternative methods such as the MNI Coordinate System (originated at the Montreal Neurological Institute and Hospital) have largely replaced Talairach for stereotaxy and other procedures. [2]
The coordinate system was first created by neurosurgeons Jean Talairach and Gabor Szikla in their work on the Talairach Atlas in 1967, creating a standardized grid for neurosurgery. [3] [4] The grid was based on the idea that distances to lesions in the brain are proportional to overall brain size (i.e., the distance between two structures is larger in a larger brain). In 1988 a second edition of the Talairach Atlas came out that was coauthored by Tournoux, and it is sometimes known as the Talairach-Tournoux system. This atlas was based on single post-mortem dissection of a human brain. [5]
The Talairach Atlas uses Brodmann areas as the labels for brain regions. [6]
The Talairach coordinate system is defined by making two anchors, the anterior commissure and posterior commissure, lie on a straight horizontal line. [7] Since these two points lie on the midsagittal plane, the coordinate system is completely defined by requiring this plane to be vertical. Distances in Talairach coordinates are measured from the anterior commissure as the origin (as defined in the 1998 edition). The y-axis points posterior and anterior to the commissures, the left and right is the x-axis, and the z-axis is in the ventral-dorsal (down and up) directions. [8] Once the brain is reoriented to these axes, the researchers must also outline the six cortical outlines of the brain: anterior, posterior, left, right, inferior, and superior. [9] In the 1967 atlas the left is with positive coordinates while in the 1988 atlas the left has negative coordinates.
By defining standard anatomical landmarks that could be identified on different subjects (the anterior and posterior commissures), it became easier to spatially warp an individual brain image obtained through Magnetic Resonance Imaging (MRI), positron emission tomography (PET) and other imaging methods to this standard Talairach space. One can then make inferences about tissue identity at a specific location by referring to the atlas.
The Brodmann area is an illustration of a cytoarchitectonic map of the human brain that was published by Korbinan Brodmann in his 1909 monogram. Brodmann's map splits the cerebral cortex into 43 differing parts, which become visible in cell-body stained histological sections. Years later, a large group of neuroscientists still utilize Brodmann's map for the localization of neuroimaging data that is obtained in living human brains. [10]
Some neuroimaging techniques, in fact, purported the use of Brodmann's area as a guideline for Talairach coordinates. Further, these technologies showcase that experimental tasks in a common reference space become possible through imaging the living human brain by registering function and having architectonic data performed and defined.
Brodmann's map proved useful in varying neuroimaging software packages and stereotaxic atlases, such as the Talairach atlas. This atlas also serves as a demonstration of the inherent problems (i.e., impressions of matches between areal borders and sulcal landmarks may lead to wrong conclusions in terms of localization of cytoarchitectonic borders or the usage of Brodmann's map without knowledge of the text that accompanies the drawing misleading researchers to false conclusions). [10]
The MNI coordinate system, also referred to as MNI space, are multiple stereotaxic brain coordinate systems created by the Montreal Neurological Institute and Hospital. [11] [12] [13] Similar to the Talairach coordinates, MNI coordinates can be used to describe the location of particular brain structures, without having to take into account any individual brain differences. However, as the Talairach system is "unrepresentative of the population at large", MNI coordinates were developed from MRI data garnered from many individuals, in an effort to create a neural coordinate system that could be more generalizable. [14] MNI coordinates have been matched to Tailarach coordinates to allow landmarks to correspond. [14]
The original MNI space was MNI 305, which was created from 305 Tailarach aligned images, from which a mean brain image was taken. [11] [15] MNI 152 (also known as ICBM 152) was created later with higher resolution MRI images that were registered to MNI 305, and from which a mean was taken. [12] [13] [15] MNI 152 is itself further made up of different atlases, with different constraints, such as linearly/non-linearly aligned and symmetric or non-symmetric brain hemispheres. [12]
Most neuroimaging software packages are able to convert from Talairach to MNI coordinates. However, disparities between MNI and Talairach coordinates can impede the comparison of results across different studies. This problem is most prevalent in situations where coordinate disparities should be corrected to reduce error, such as coordinate-based meta-analyses. There is a possibility that these disparities can be assuaged through the Lancaster transform, which can be adopted in order to minimize the variability in the literature regarding spatial normalization strategies. [16]
Non-linear registration is the process of mapping Talairach coordinates to subject-specific coordinates and generating a non-linear map in an attempt to compensate for actual shape differences between the two. Registration is usually nonlinear because the Talairach atlas is not a simple rigid transform (or even affine transform) of a subject brain. [17]
The Talairach atlas is still commonly used in terms of the neuroimaging techniques that are available, but the lack of a three-dimensional model of the original brain makes it difficult for researchers to map locations from three-dimensional anatomical MRI images to the atlas automatically. Previous methods such as MNI have tried to assuage this issue through linear and piecewise mapping between the Talairach and the MNI template, but can only account for differences in overall brain orientation and size and thus cannot correctly account for actual shape differences. [18]
Current target brains are not suitable for current research (i.e., are average, can only be used in low-resolution MRI target brain mapping studies or are single brain). Optimized high-resolution brain template (HRBT), a high-resolution MRI target brain, is a technique that can aid in the issues named above. This optimization can be performed to help reduce individual anatomical biases of the original ICBM HBRT. The optimized HRBT is more adept at anatomically matching groups of brains. [19]
Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.
In neuroanatomy, the precuneus is the portion of the superior parietal lobule on the medial surface of each brain hemisphere. It is located in front of the cuneus. The precuneus is bounded in front by the marginal branch of the cingulate sulcus, at the rear by the parieto-occipital sulcus, and underneath by the subparietal sulcus. It is involved with episodic memory, visuospatial processing, reflections upon self, and aspects of consciousness.
Brodmann area 9, or BA9, refers to a cytoarchitecturally defined portion of the frontal cortex in the brain of humans and other primates. It contributes to the dorsolateral and medial prefrontal cortex.
Statistical parametric mapping (SPM) is a statistical technique for examining differences in brain activity recorded during functional neuroimaging experiments. It was created by Karl Friston. It may alternatively refer to software created by the Wellcome Department of Imaging Neuroscience at University College London to carry out such analyses.
Stereotactic surgery is a minimally invasive form of surgical intervention that makes use of a three-dimensional coordinate system to locate small targets inside the body and to perform on them some action such as ablation, biopsy, lesion, injection, stimulation, implantation, radiosurgery (SRS), etc.
Functional integration is the study of how brain regions work together to process information and effect responses. Though functional integration frequently relies on anatomic knowledge of the connections between brain areas, the emphasis is on how large clusters of neurons – numbering in the thousands or millions – fire together under various stimuli. The large datasets required for such a whole-scale picture of brain function have motivated the development of several novel and general methods for the statistical analysis of interdependence, such as dynamic causal modelling and statistical linear parametric mapping. These datasets are typically gathered in human subjects by non-invasive methods such as EEG/MEG, fMRI, or PET. The results can be of clinical value by helping to identify the regions responsible for psychiatric disorders, as well as to assess how different activities or lifestyles affect the functioning of the brain.
Jean Talairach was a psychiatrist and neurosurgeon who practiced at the Sainte-Anne Hospital Center in Paris, and who is noted for the Talairach coordinates, which are relevant in stereotactic neurosurgery.
The posterior cingulate cortex (PCC) is the caudal part of the cingulate cortex, located posterior to the anterior cingulate cortex. This is the upper part of the "limbic lobe". The cingulate cortex is made up of an area around the midline of the brain. Surrounding areas include the retrosplenial cortex and the precuneus.
FreeSurfer is a brain imaging software package originally developed by Bruce Fischl, Anders Dale, Martin Sereno, and Doug Greve. Development and maintenance of FreeSurfer is now the primary responsibility of the Laboratory for Computational Neuroimaging at the Athinoula A. Martinos Center for Biomedical Imaging. FreeSurfer contains a set of programs with a common focus of analyzing magnetic resonance imaging (MRI) scans of brain tissue. It is an important tool in functional brain mapping and contains tools to conduct both volume based and surface based analysis. FreeSurfer includes tools for the reconstruction of topologically correct and geometrically accurate models of both the gray/white and pial surfaces, for measuring cortical thickness, surface area and folding, and for computing inter-subject registration based on the pattern of cortical folds.
Neuronavigation is the set of computer-assisted technologies used by neurosurgeons to guide or "navigate" within the confines of the skull or vertebral column during surgery, and used by psychiatrists to accurately target rTMS. The set of hardware for these purposes is referred to as a neuronavigator.
Medical image computing (MIC) is an interdisciplinary field at the intersection of computer science, information engineering, electrical engineering, physics, mathematics and medicine. This field develops computational and mathematical methods for solving problems pertaining to medical images and their use for biomedical research and clinical care.
Resting state fMRI is a method of functional magnetic resonance imaging (fMRI) that is used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an explicit task is not being performed. A number of resting-state brain networks have been identified, one of which is the default mode network. These brain networks are observed through changes in blood flow in the brain which creates what is referred to as a blood-oxygen-level dependent (BOLD) signal that can be measured using fMRI.
Peter T. Fox is a neuroimaging researcher and neurologist at the University of Texas Health Science Center at San Antonio. He is a professor in the Department of Radiology with joint appointments in Radiology, Medicine, and Psychiatry. He is the founding director of the Research Imaging Institute.
The following outline is provided as an overview of and topical guide to brain mapping:
A brain atlas is composed of serial sections along different anatomical planes of the healthy or diseased developing or adult animal or human brain where each relevant brain structure is assigned a number of coordinates to define its outline or volume. Brain atlases are contiguous, comprehensive results of visual brain mapping and may include anatomical, genetic or functional features. A functional brain atlas is made up of regions of interest, where these regions are typically defined as spatially contiguous and functionally coherent patches of gray matter.
CONN is a Matlab-based cross-platform imaging software for the computation, display, and analysis of functional connectivity in fMRI in the resting state and during task.
Dynamic causal modeling (DCM) is a framework for specifying models, fitting them to data and comparing their evidence using Bayesian model comparison. It uses nonlinear state-space models in continuous time, specified using stochastic or ordinary differential equations. DCM was initially developed for testing hypotheses about neural dynamics. In this setting, differential equations describe the interaction of neural populations, which directly or indirectly give rise to functional neuroimaging data e.g., functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG) or electroencephalography (EEG). Parameters in these models quantify the directed influences or effective connectivity among neuronal populations, which are estimated from the data using Bayesian statistical methods.
Brain–body interactions are patterns of neural activity in the central nervous system to coordinate the activity between the brain and body. The nervous system consists of central and peripheral nervous systems and coordinates the actions of an animal by transmitting signals to and from different parts of its body. The brain and spinal cord are interwoven with the body and interact with other organ systems through the somatic, autonomic and enteric nervous systems. Neural pathways regulate brain–body interactions and allow to sense and control its body and interact with the environment.
Dimitri Van De Ville is a Swiss and Belgian computer scientist and neuroscientist specialized in dynamical and network aspects of brain activity. He is a professor of bioengineering at EPFL and the head of the Medical Image Processing Laboratory at EPFL's School of Engineering.
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