Brain mapping is a set ofneuroscience techniques predicated on the mapping of (biological) quantities or properties onto spatial representations of the (human or non-human)brain resulting inmaps.
In 2024, a team of 287 researchers completed a full brain mapping of an adult animal (aDrosophila melanogaster, or fruit fly) and published their results inNature.[1][2]
Allneuroimaging 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 (seefMRI). One such map, called aconnectogram, 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 byfractional anisotropy and strength of connection.[3] At higher resolutions brain maps are calledconnectomes. These maps incorporate individual neural connections in the brain and are often presented aswiring diagrams.[4]
Brain mapping techniques are constantly evolving, and rely on the development and refinement of image acquisition, representation, analysis, visualization and interpretation techniques.[5] 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 inscientific journals 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 singlevoxel. 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 individualbrain circuits. 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, or medical diagnosis in ways which have not been scientifically validated.[6][page needed]
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.[7][page needed]
Following a series of meetings, the International Consortium for Brain Mapping (ICBM) evolved.[12][page needed] The ultimate goal is to develop flexible computationalbrain atlases.
The Eyewire Museum is an interactive digital catalog visualizing data of mouse retinal cells.[13]
The interactive and citizen science websiteEyewire maps mices' retinal cells and was launched in 2012. In 2021, the most comprehensive 3D map of the human brain was published by researchers atGoogle. 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 about 5,300 pieces of about 30nanometer thickness which were then each scanned with anelectron microscope. The interactive map required 1.4petabytes of storage-space.[14][15] 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.[16][17]
In October 2021, the BRAIN Initiative Cell Census Network 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 theprimary motor cortex.[18][19][20]
In 2024, FlyWire, a team of 287 researchers spanning 76 institutions completed a brain mapping, or connectome, of an adult animal (aDrosophila melanogaster, or fruit fly) and published their results inNature.[1] Prior to this, the only adult animal to have its brain entirely reconstructed was the nematodeCaenorhabditis elegans, but the fruit fly brain map is the first "complete map of any complex brain", according to Murthy, one of the researchers involved.[2] Primary mapping data was collected throughelectron microscopy, assisted byartificial intelligence andcitizen scientists, who corrected errors that artificial intelligence made. The resulting model had more than 140,000 neurons with over 50 million synapses.[21] From the model, research expect to identify how the brain creates new connections for functions such as vision, creatingdigital twin equivalents to track how segments of the neuron connection map interact to external signals, including the nervous system.[22]
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 isogenicC. elegans worms, each at a different stage of development.[23][24] 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.[25]
In August 2021, scientists of theMICrONS program, launched in 2016,[26] 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".[27][28] 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" – theMICrONS Explorer.[29]
In 2022, a first spatiotemporal cellular atlas of theaxolotl brain development andregeneration, the interactiveAxolotl Regenerative Telencephalon Interpretation via Spatiotemporal Transcriptomic Atlas, revealed key insights about axolotlbrain regeneration.[30][31]
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^Pechura, Constance M.; Martin, Joseph B. (1991).Mapping the Brain and Its Functions: Integrating Enabling Technologies Into Neuroscience Research. Institute of Medicine (U.S.). Committee on a National Neural Circuitry Database.doi:10.17226/1816.ISBN978-0-309-04497-4.PMID25121208.
^Koslow, Stephen H.; Huerta, Michael F., eds. (1997).Neuroinformatics: An Overview of the Human Brain Project. Mahwah, New Jersey: L. Eribaum.ISBN978-1-134-79842-1.
^Meirovitch, Yaron; Kang, Kai; Draft, Ryan W.; Pavarino, Elisa C.; Henao E., Maria F.; Yang, Fuming; Turney, Stephen G.; Berger, Daniel R.; Peleg, Adi; Schalek, Richard L.; Lu, Ju L.; Tapia, Juan-Carlos; Lichtman, Jeff W. (September 2021). "Neuromuscular connectomes across development reveal synaptic ordering rules".bioRxiv.doi:10.1101/2021.09.20.460480.S2CID237598181.
^Serag, Ahmed; Aljabar, Paul; Ball, Gareth; Counsell, Serena J.; Boardman, James P.; Rutherford, Mary A.; Edwards, A. David; Hajnal, Joseph V.; Rueckert, Daniel (2012). "Construction of a consistent high-definition spatio-temporal atlas of the developing brain using adaptive kernel regression".NeuroImage.59 (3):2255–65.doi:10.1016/j.neuroimage.2011.09.062.PMID21985910.S2CID9747334.
F.J. Chen (2006).Trends in Brain Mapping Research.
F.J. Chen (2006).Progress in Brain Mapping Research.
Koichi Hirata (2002).Recent Advances in Human Brain Mapping: Proceedings of the 12th World Congress of the International Society for Brain Electromagnetic Topography (ISBET 2001).
Konrad Maurer and Thomas Dierks (1991).Atlas of Brain Mapping: Topographic Mapping of Eeg and Evoked Potentials.
Konrad Maurer (1989).Topographic Brain Mapping of Eeg and Evoked Potentials.
Arthur W. Toga and John C. Mazziotta (2002).Brain Mapping: The Methods.
Tatsuhiko Yuasa, James Prichard and S. Ogawa (1998).Current Progress in Functional Brain Mapping: Science and Applications.
