The human brain is a complex and dynamic organ responsible for regulating virtually everything we think, feel, and do. While researchers have made impressive strides in understanding its underlying structure and function, we are still learning about how its various regions and networks interact, and how they are perturbed in different disease states. In a new paper published in Communications Biology, a group of neuroscientists has proposed a novel framework for mapping disrupted brain function, using a combination of focal and connectomic approaches. Here, we explore their findings and how they could pave the way for new insights into the workings of the brain.
In this study, data from Trevisi et al.20 was reanalyzed to identify cortical maps of focal regions critical for specific categories of sensorimotor behaviors and to extend these maps to connected regions across the brain. The study used retrospective data from 147 consecutive drug-resistant focal epilepsy patients who underwent intracranial recording at the National Hospital for Neurology and Neurosurgery, London, as part of clinical assessment prior to epilepsy surgery. Thirty-seven patients were identified to have at least one stimulation in the medial frontal region, spatially confined to the medial wall area dorsal to the corpus callosum and rostral to the caudal bank of the marginal sulcus. The participants were aged 19-68 years old with a mean age of 33.86 years old. Participants were asked to perform a set of test actions, including rest, Barré and/or Mingazzini test, repeated movements of the upper and lower limbs, and during counting, reading, or repetitive monosyllabic verbalization. Three clinicians classified the observed behavioral responses as positive motor, negative motor, or speech disturbances. The study used cortical stimulation procedures, where the stimulations were delivered with biphasic rectangular pulses of AC-current at 50 Hz. The intensity was gradually increased from 0.5 to 7 mA in increments of 0.5-1 mA until the occurrence of a clinical sign or until after-discharges were detected on EEG monitoring. The study employed a voxel-wise repeated-measures general linear model to analyze the data, with electrode density as the dependent variable, and behavioral effect and subject as the independent variables. Within-subject non-sphericity of errors was accounted for using standard procedures. The study found that connective disruptive mapping, using large-scale high-resolution diffusion tensor imaging from the Human Connectome Project, identified the white matter connectivity matrices for the participants. The study’s findings suggest that the approach used here facilitated group analysis of sparse data accounting for between-subject variation in functional-anatomical relationships not captured by anatomical registrations, analogous to the approach used in meta-analytic modeling of functional activation data.
In conclusion, the framework presented in this article offers a powerful tool for studying transiently disrupted brain function. By integrating focal and connectomic mapping techniques, this approach allows researchers to gain a more comprehensive understanding of how activity in specific brain regions affects broader neural networks. While there is still much to be explored in this field, the framework presented here provides a promising starting point that could ultimately help to improve our understanding and treatment of neurological disorders. Whether you are a researcher or simply interested in the workings of the brain, this article offers valuable insights into the cutting-edge techniques being used to explore the complexities of the human mind.
