Novel role for transcranial magnetic stimulation to study post-traumatic respiratory neuroplasticity

Stimulation-induced respiratory enhancement in corticothalamic regions

OBJECTIVE

We aimed to identify corticothalamic areas and electrical stimulation paradigms that optimally enhance breathing.

METHODS

Twenty-nine patients with medically intractable epilepsy were prospectively recruited in an epilepsy monitoring unit while undergoing stereoelectroencephalographic evaluation. Direct electrical stimulation in cortical and thalamic regions was carried out using low (<1 Hz) and high (≥10 Hz) frequencies, and low (<5 mA) and high (≥5 mA) current intensities, with pulse width of .1 ms. Electrocardiography, arterial oxygen saturation (SpO2 ), end-tidal carbon dioxide (ETCO2 ), oronasal airflow, and abdominal and thoracic plethysmography were monitored continuously during stimulations. Airflow signal was used to estimate breathing rate, tidal volume, and minute ventilation (MV) changes during stimulation, compared to baseline.

RESULTS

Electrical stimulation increased MV in the amygdala, anterior cingulate, anterior insula, temporal pole, and thalamus, with an average increase in MV of 20.8% ± 28.9% (range = 0.2%-165.6%) in 19 patients. MV changes were associated with SpO2 and ETCO2 changes (p < .001). Effects on respiration were parameter and site dependent. Within amygdala, low-frequency stimulation of the medial region produced 78.49% greater MV change (p < .001) compared to high-frequency stimulation. Longer stimulation produced greater MV changes (an increase of 4.47% in MV for every additional 10 s, p = .04).

SIGNIFICANCE

Stimulation of amygdala, anterior cingulate gyrus, anterior insula, temporal pole, and thalamus, using certain stimulation paradigms, enhances respiration. Among tested paradigms, low-frequency, low-intensity, long-duration stimulation of the medial amygdala is the most effective breathing enhancement stimulation strategy. Such approaches may pave the way for the future development of neuromodulatory techniques that aid rescue from seizure-related apnea, potentially as a targeted sudden unexpected death in epilepsy prevention method.

La stimulation magnétique répétée pour le traitement des traumas spinaux

Les traumas spinaux induisent des déficits moteurs et sensoriels. La mise au point de thérapies visant à rétablir les fonctions altérées à la suite d’une lésion de la moelle épinière est donc nécessaire. La stimulation magnétique répétée (SMr) est une thérapie innovante et non invasive utilisée pour moduler l’activité de réseaux neuronaux dans diverses maladies neurologiques, telles que la maladie de Parkinson, ou psychiatriques, telles que le trouble bipolaire. Son utilisation chez les personnes atteintes de traumas spinaux pourrait avoir des effets fonctionnels bénéfiques. Des études réalisées in vitro, in vivo et ex vivo ont permis de comprendre en partie les mécanismes sous-jacents à la modulation de l’activité neuronale induite par les protocoles de SMr. Son utilisation dans des modèles précliniques de lésion médullaire a de plus montré des effets bénéfiques fonctionnels. Ainsi, la SMr pourrait potentialiser la récupération des fonctions perdues après un trauma spinal.

Breathing control, brain, and bodily self-consciousness: Toward immersive digiceuticals to alleviate respiratory suffering

Breathing is peculiar among autonomic functions through several characteristics. It generates a very rich afferent traffic from an array of structures belonging to the respiratory system to various areas of the brain. It is intimately associated with bodily movements. It bears particular relationships with consciousness as its efferent motor control can be automatic or voluntary. In this review within the scope of "respiratory neurophysiology" or "respiratory neuroscience", we describe the physiological organisation of breathing control. We then review findings linking breathing and bodily self-consciousness through respiratory manipulations using virtual reality (VR). After discussing the currently admitted neurophysiological model for dyspnea, as well as a new Bayesian model applied to breathing control, we propose that visuo-respiratory paradigms -as developed in cognitive neuroscience- will foster insights into some of the basic mechanisms of the human respiratory system and will also lead to the development of immersive VR-based digital health tools (i.e. digiceuticals).