Brain mapping is a set of

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...

techniques predicated on the mapping of (biological) quantities or properties onto spatial representations of the (human or non-human)

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

resulting in

map A map is a symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. Many maps are static, fixed to paper or some other durable medium, while others are dynamic or interactive. Although ...

s. According to the definition established in 2013 by

Society for Brain Mapping and Therapeutics The International Brain Mapping and Intraoperative Surgical Planning Society (IBMISPS-Tax ID 20-2793206) DBA The Society for Brain Mapping and Therapeutics (SBMT) is a non-profit biomedical association (501c6) principally concerned with Brain Mapp ...

(SBMT), brain mapping is specifically defined, in summary, as the study of the

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

and function of the brain and

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

through the use of

imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materials and methods to create, preserve, or duplicate images. ...

, immunohistochemistry, molecular &

optogenetics Optogenetics is a biological technique to control the activity of neurons or other cell types with light. This is achieved by expression of light-sensitive ion channels, pumps or enzymes specifically in the target cells. On the level of individ ...

, stem cell and

cellular biology Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and ...

engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more speciali ...

neurophysiology Neurophysiology is a branch of physiology and neuroscience that studies nervous system function rather than nervous system architecture. This area aids in the diagnosis and monitoring of neurological diseases. Historically, it has been dominated b ...

and nanotechnology.

Overview

All

neuroimaging Neuroimaging is the use of quantitative (computational) techniques to study the structure and function of the central nervous system, developed as an objective way of scientifically studying the healthy human brain in a non-invasive manner. Incr ...

is considered part of brain mapping. Brain mapping can be conceived as a higher form of neuroimaging, producing brain images supplemented by the result of additional (imaging or non-imaging) data processing or analysis, such as maps projecting (measures of) behavior onto brain regions (see

fMRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area ...

). One such map, called a

connectogram Connectograms are graphical representations of connectomics, the field of study dedicated to mapping and interpreting all of the white matter fiber connections in the human brain. These circular graphs based on diffusion MRI data utilize graph theo ...

, depicts cortical regions around a circle, organized by lobes. Concentric circles within the ring represent various common neurological measurements, such as cortical thickness or curvature. In the center of the circles, lines representing white matter fibers illustrate the connections between cortical regions, weighted by

fractional anisotropy Fractional anisotropy (FA) is a scalar value between zero and one that describes the degree of anisotropy of a diffusion process. A value of zero means that diffusion is isotropic, i.e. it is unrestricted (or equally restricted) in all directions. ...

and strength of connection. At higher resolutions brain maps are called

connectomes A connectome () is a comprehensive map of neural connections in the brain, and may be thought of as its "wiring diagram". An organism's nervous system is made up of neurons which communicate through synapses. A connectome is constructed by tr ...

. These maps incorporate individual neural connections in the brain and are often presented as wiring diagrams. Brain mapping techniques are constantly evolving, and rely on the development and refinement of image acquisition, representation, analysis, visualization and interpretation techniques. Functional and structural neuroimaging are at the core of the mapping aspect of brain mapping. Some scientists have criticized the brain image-based claims made in

scientific journals In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such as s ...

and the popular press, like the discovery of "the part of the brain responsible" things like love or musical abilities or a specific memory. Many mapping techniques have a relatively low resolution, including hundreds of thousands of neurons in a single

voxel In 3D computer graphics, a voxel represents a value on a regular grid in three-dimensional space. As with pixels in a 2D bitmap, voxels themselves do not typically have their position (i.e. coordinates) explicitly encoded with their values. I ...

. Many functions also involve multiple parts of the brain, meaning that this type of claim is probably both unverifiable with the equipment used, and generally based on an incorrect assumption about how brain functions are divided. It may be that most brain functions will only be described correctly after being measured with much more fine-grained measurements that look not at large regions but instead at a very large number of tiny individual

brain circuits A neural circuit is a population of neurons interconnected by synapses to carry out a specific function when activated. Neural circuits interconnect to one another to form large scale brain networks. Biological neural networks have inspired the ...

. Many of these studies also have technical problems like small sample size or poor equipment calibration which means they cannot be reproduced - considerations which are sometimes ignored to produce a sensational journal article or news headline. In some cases the brain mapping techniques are used for commercial purposes,

lie detection Lie detection is an assessment of a verbal statement with the goal to reveal a possible intentional deceit. Lie detection may refer to a cognitive process of detecting deception by evaluating message content as well as non-verbal cues. It also ma ...

, or medical diagnosis in ways which have not been scientifically validated.

History

In the late 1980s in the United States, the Institute of Medicine of the National Academy of Science was commissioned to establish a panel to investigate the value of integrating neuroscientific information across a variety of techniques. Of specific interest is using structural and functional magnetic resonance imaging (fMRI),

diffusion MRI Diffusion-weighted magnetic resonance imaging (DWI or DW-MRI) is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images. It ...

(dMRI),

magnetoencephalography Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs (s ...

(MEG), electroencephalography (

EEG Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

), positron emission tomography (PET),

Near-infrared spectroscopy Near-infrared spectroscopy (NIRS) is a spectroscopic method that uses the near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm). Typical applications include medical and physiological diagnostics and research inc ...

(NIRS) and other non-invasive scanning techniques to map

physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

, perfusion, function and

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...

s of the human brain. Both healthy and

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

d brains may be mapped to study

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

, learning, aging, and drug effects in various populations such as people with

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social wit ...

, autism, and

clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Intro ...

. This led to the establishment of the

Human Brain Project The Human Brain Project (HBP) is a large ten-year scientific research project, based on exascale supercomputers, that aims to build a collaborative ICT-based scientific research infrastructure to allow researchers across Europe to advance knowl ...

. It may also be crucial to understanding traumatic brain injuries (as in the case of Phineas Gage) and improving brain injury treatment. Following a series of meetings, the International Consortium for Brain Mapping (ICBM) evolved. The ultimate goal is to develop flexible computational brain atlases.

Achievements

The interactive and citizen science website Eyewire maps mices' retinal cells and was launched in 2012. In 2021, the most comprehensive 3D map of the human brain was published by an U.S. IT company. It shows neurons and their connections along with blood vessels and other components of a millionth of a brain. For the map, the 1 mm³ sized fragment was sliced into over 5 000 nanometers-thin pieces which were scanned with an

electron microscope An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...

. The interactive map required 1.4

petabyte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...

s of storage-space. About two months later, scientists reported that they created the first complete neuron-level-resolution 3D map of a monkey brain which they scanned via a new method within 100 hours. They made only a fraction of the 3D map publicly available as the entire map takes more than 1 petabyte of storage space even when compressed. In October 2021, the BRAIN Initiative Cell Census Network (BICCN) concluded the first phase of a long-term project to generate an atlas of the entire mouse (mammalian) brain with 17 studies, including an atlas and census of cell types in the primary motor cortex.

Brain development

In 2021, the first connectome that shows how an animal's brain changes throughout its lifetime was reported. Scientists mapped and compared the whole brains of eight isogenic ''

C. elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (r ...

'' worms, each at a different stage of development. Later that year, scientists combined electron microscopy and brainbow imaging to show for the first time the development of a mammalian neural circuit. They reported the complete wiring diagrams between the CNS and muscles of ten individual mice.

Vision

In August 2021, scientists of the

MICrONS The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

program, launched in 2016, published a functional connectomics dataset that "contains calcium imaging of an estimated 75,000 neurons from primary visual cortex (VISp) and three higher visual areas (VISrl, VISal and VISlm), that were recorded while a mouse viewed natural movies and parametric stimuli". Based on this data they also published "interactive visualizations of anatomical and functional data that span all 6 layers of mouse primary visual cortex and 3 higher visual areas (LM, AL, RL) within a cubic millimeter volume" – the ''MICrONS Explorer''.

Brain regeneration

In 2022, a first spatiotemporal cellular atlas of the axolotl brain development and

regeneration Regeneration may refer to: Science and technology * Regeneration (biology), the ability to recreate lost or damaged cells, tissues, organs and limbs * Regeneration (ecology), the ability of ecosystems to regenerate biomass, using photosynthesis ...

, the interactive ''Axolotl Regenerative Telencephalon Interpretation via Spatiotemporal Transcriptomic Atlas '', revealed key insights about axolotl

brain regeneration A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

Current Atlas tools

* Talairach Atlas, 1988 * Harvard Whole Brain Atlas, 1995 * MNI Template, 1998 (The standard template of SPM and International Consortium for Brain Mapping) * Atlas of the Developing Human Brain, 2012

Full SBMT definition

Brain mapping is the study of the anatomy and function of the brain and spinal cord through the use of imaging (including intra-operative, microscopic, endoscopic and multi-modality imaging), immunohistochemistry, molecular & optogenetics, stem cell and cellular biology, engineering (material, electrical and biomedical), neurophysiology and nanotechnology.

References

External links

Epilepsy & Brain Mapping Program

BrainMapping.org project

National Centers for Biomedical Computing

Mapology.org

Human Brain Mapping

National Center for Multi-Scale Study of Cellular Networks

National Center for Biomedical Ontology

Physics-based Simulation of Biological Structures

National Alliance for Medical Imaging Computing

Informatics for Integrating Biology and the Bedside

National Center for Integrative Biomedical Informatics

Elekta Neuromag

Brain Mapping Foundation

Interactive Brain Map by InformED

Society for Brain Mapping and Therapeutics
* July 20, 2016 on Nature video channel

MRICloud.org {{Neuroscience Neurophysiology Neuroimaging Neurosurgery Bioinformatics