Combined voltammetry and optical brain imaging: toward high resolution neurochemical measurements

The question of the mechanisms by which cellular interactions in the brain are converted into integrative behavioral phenomena is closely related to functional localization. Electrophysiology is usually limited in its ability to display information about the functioning of neural circuits with sufficient spatial resolution, although the temporal resolution is almost always very high. Other modern methods for recording the functional characteristics of neural activity in the brain vary considerably in spatial and temporal resolution. Voltammetry is one of the key instrumental methods used in neurobiology to measure neurotransmitter release and dynamics in vivo. It is similar to electrophysiology in terms of temporal resolution, but spatial resolution remains low. This method records changes in the concentration of chemicals, typically neurotransmitters, in the brain's extracellular environment with sufficient temporal resolution to capture release peaks. However, as this monitoring is performed at a single location or target, the technique does not provide information about the spatial distribution of the recorded signal characteristics. Various techniques for functional optical imaging of brain structure and activity offer relatively high spatial resolution, often accompanied by adequate temporal resolution. Some of these methods are suitable for visualizing neural activity in both 2D and 3D. However, while functional brain imaging allows areas of neural activity to be identified, it typically does not provide quantitative information about changes in the concentration levels of specific molecules. A significant challenge would be to combine the key advantages of voltammetry and functional optical brain imaging, i.e., to obtain continuous quantitative information on the concentration of neurochemically active molecules across many areas of the investigated brain region with sufficiently high temporal and spatial resolution. This review discusses the current state of voltammetry and functional brain imaging techniques, as well as the hypothetical possibilities for combining them based on the experimental data obtained to date. .