Topography

Definition: The term topography refers to the mapping of the changes in brain hemodynamics associated with neuronal activity onto the brain cortex or a specific surface. Topographic maps represent two-dimensional images generated by measuring the changes in the brain optical properties at multiple measurement sites (or channels) that can be used to localize where brain activity occurs in the regions probed by the fNIRS array.

Alternative definition: The term topography can be understood in relation to two leading themes. The first concerns the topographical division of the brain. It is based on the developmental pattern of individual brain structures. For this reason, it is often called a developmental or ontogenetic division (from the Latin ontogenesis, which means personal development). In this division, the components of the brain are the primary brain follicles of the embryo. The advantages of this division are its precision and reference to the development of structures. Its disadvantages are the difficulty of remembering and discrepancy with the functional division. Sometimes structures belonging to two different secondary cerebral vesicles have similar functions. Another topic related to topology is the so-called topographic map of the brain, that is, the ordering of elements in the structure – in particular, the ordered spatial relationship between the distribution of nerve receptors in the corpus callosum area and the associated spread of neurons representing the same functions in the cortical areas of the brain. This is one of the key principles of brain organization, shaped throughout development. In theoretical models, spatial topography in connectivity is postulated to have the function of ensuring the fidelity of information transmission in the network. The topographical organization of connections also has the potential to generate complex abstract representations through topographical overlap.

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References: https://doi.org/10.1016/j.neuroimage.2012.03.049

Related terms: Multichannel, Tomography