This review outlines the technological principles of neural–computer interface (NCI) construction, classifying them according to: (1) the degree of intervention (invasive, semi-invasive, and non-invasive); (2) the direction of signal communication, including BCI (brain–computer interface) for converting neural activity into commands for external devices, CBI (computer–brain interface) for translating artificial signals into stimuli for the CNS, and BBI (brain–brain interface) for direct brain-to-brain interaction systems that account for agency; and (3) the mode of user interaction with technology (active, reactive, passive). For each NCI type, we detail the fundamental data processing principles, covering signal registration, digitization, preprocessing, classification, encoding, command execution, and stimulation, alongside engineering implementations ranging from EEG/MEG to intracortical implants and from transcranial magnetic stimulation (TMS) to intracortical microstimulation (ICMS). We also review mathematical modeling methods for NCIs, focusing on optimizing the extraction of informative features from neural signals—decoding for BCI and encoding for CBI—followed by a discussion of quasi-real-time operation and the use of DSP and neuromorphic chips. Quantitative metrics and rehabilitation measures for evaluating NCI system effectiveness are considered. Finally, we highlight promising future research directions, such as the development of electrochemical interfaces, biomimetic hierarchical systems, and energy-efficient technologies capable of expanding brain functionality.

The article provides a summary and critical analysis of literature data, primarily from the last five years, on neural interfaces. It overviews experimental findings and clinical outcomes from applying neural interfaces for the enhancement of human capabilities in interacting with the environment. It also illustrates how employing the latest advancements in electronics, nanoscale bioengineering, and artificial intelligence improves quality of life or can be utilized for the purposes of regenerative medicine. The review highlights the most promising types of neural interfaces, with a particular emphasis on invasive technologies and the use of cutting-edge developments in implantable materials with high biocompatibility, durability, and optimized biophysical properties. Materials for invasive technologies are evaluated in the light of their applicability for specific biomedical purposes, accompanied by a comparative analysis. Significant attention is paid to the latest technologies in the fields of biomimetics and electrical biostimulation, as well as innovative approaches to the applied aspects of brain and spinal interfaces. Thus, this review serves as a valuable source of information for students and professionals whose educational and professional interests are aimed at diving deeper into the world of neural interfaces.