Preoperative mapping of functionally significant (specifically, eloquent) areas of the cerebral cortex using functional magnetic resonance imaging (fMRI) enables assessment of their location relative to the surgical target, allowing for more effective and safe planning of neurosurgical intervention. In this context, areas of increased functional activity during the performance of a specific test task are typically identified based on data showing an increase in the BOLD (Blood Oxygen Level-Dependent) signal—the so-called positive BOLD response. Meanwhile, according to current consensus, the cerebral support of any activity relies on the activity of functional neuroanatomical systems involving a number of components—structures and brain regions whose level of functional activity during engagement in an activity can either increase or decrease. A decrease in the BOLD signal, corresponding in the shape of its time–intensity curve to a mirror reflection of the positive BOLD response and referred to as the negative BOLD response, has been described in the literature as an important characteristic of the mechanisms underlying activity support. However, this phenomenon has not yet found diagnostic application, which may be due to its multifactorial nature. This review aims to analyze the role of the negative BOLD response in the implementation of human cognitive and motor functions and to evaluate its potential for use during preoperative fMRI-based mapping. Here, we discusses the possible mechanisms underlying the origin of a negative BOLD response, its relationship with inhibitory processes, and its contribution to the neuronal support of human activity. Approaches to recording this phenomenon are also described, specific clinical examples are provided, and the prospects for its implementation into preoperative diagnostic practice are discussed.
Myznikov et al. (Wed,) studied this question.