The Breakdown of Cross-Frequency Coupling Between Brain and Body Rhythms in Clinical Conditions
Presented by: Asa Young
Fundamental ties between brain and body is a ubiquitous thesis that has emerged in various shapes and sizes, yet always constant in its central message: the substrates that combine the brain to its neuroanatomical foundations are necessary to the health and integrity of both the system and the agent that pilots it.
I re-engage this topic under the auspices of the current trend in cognitive neuroscience towards systematic examination of the brain’s neuronally-generated electromagnetic field as the primary seat of consciousness. It is suggested the dynamics of the complex array of neural rhythms are, in fact, the dynamics of the conscious agent within. This is further extended to include the peripheral nervous system that sustains and stimulates the central brain. As such, the capacity for phenomenal experience that we attribute to the brain’s rhythmic neural hierarchy is, rather, a product of the larger, spatially distributed hierarchy of brain-body rhythms extending from the ultraslow peristaltic cycles to the higher frequency EEG bands and those rhythms that fall between. The current presentation is conducted in support of this premise through the examination of the failure of this synchronous architecture as a causal factor in brain-body pathology.
Bodily illnesses and neuropsychiatric disorders are frequently comorbid. It is hypothesized that illness, at either end of the rhythmic correspondence, will upset the balance of the oscillatory hierarchy and compromise the oscillator at the other end. Chronic gut inflammation precedes the development of Alzheimer’s Disease and depression increases the risks of cardiovascular disease, to name just a few examples. The central oscillators and their respective phase-phase and phase-amplitude relationships are detailed, as well as the manner of their failure in several corresponding neuropsychiatric disorders. The intrinsic pacemakers reviewed herein provide biological targets for therapeutic interventions to repair the oscillator system and mitigate the severity of mental illness. The embodied and enactive neuroscientific position benefits from the reframing of this thesis through the provision of a greater ability to quantify the extent of brain-body connection with cross-frequency quantifications between peripheral and central nervous systems.