Prefrontal cortex activation during incremental inspiratory loading in healthy participants

Luana T Melo; Antenor Rodrigues; Elis Emmanuelle Cabral; Takako Tanaka; Ewan C Goligher; Laurent Brochard; W Darlene Reid

doi:10.1016/j.resp.2021.103827

Prefrontal cortex activation during incremental inspiratory loading in healthy participants

Respir Physiol Neurobiol. 2022 Feb:296:103827. doi: 10.1016/j.resp.2021.103827. Epub 2021 Nov 20.

Authors

Luana T Melo¹, Antenor Rodrigues², Elis Emmanuelle Cabral³, Takako Tanaka⁴, Ewan C Goligher⁵, Laurent Brochard⁶, W Darlene Reid⁷

Affiliations

¹ Department of Physical Therapy, University of Toronto, Ontario, Canada; Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada.
² Department of Physical Therapy, University of Toronto, Ontario, Canada; Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada. Electronic address: antenor.rodrigues@unityhealth.to.
³ Department of Physical Therapy, University of Toronto, Ontario, Canada; Performance Lab, Pneumocardiovascular and Respiratory Muscles (PneumoCardioVascular Lab/HUOL), Department of Physical Therapy, Federal University of Rio Grande do Norte (UFRN), Rio Grande do Norte, Brazil.
⁴ Department of Physical Therapy, University of Toronto, Ontario, Canada; Department of Cardiopulmonary Rehabilitation Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
⁵ Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada.
⁶ Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada.
⁷ Department of Physical Therapy, University of Toronto, Ontario, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; KITE, Toronto Rehabilitation Institute, University Health Network, Toronto, Canada.

PMID: 34808586
DOI: 10.1016/j.resp.2021.103827

Abstract

We aimed to investigate whether changes in prefrontal cortex (PFC) oxyhemoglobin (O₂Hb) and deoxyhemoglobin (HHb) associates with inspiratory muscle effort during inspiratory threshold loading (ITL) in healthy participants. Participants performed an incremental ITL. Breathing pattern, partial pressure of end-tidal CO₂ (P_ETCO₂), mouth pressure and O₂Hb and HHb over the right dorsolateral PFC, sternocleidomastoid (SCM), and diaphragm/intercostals (Dia/IC) were monitored. Fourteen healthy participants (8 men; 29 ± 5 years) completed testing. Dyspnea was higher post- than pre-ITL (5 ± 1 vs. 0 ± 1, respectively; P<0.05). PFC O₂Hb increased (P < 0.001) and HHb decreased (P = 0.001) at low loads but remained stable with increasing ITL intensities. PFC total hemoglobin increased at task failure compared to rest. SCM HHb increased throughout increasing intensities. SCM and Dia/IC total hemoglobin increased in the at task failure compared to rest. P_ETCO₂ did not change (P = 0.528). PFC is activated early during the ITL but does not show central fatigue at task failure despite greater dyspnea and an imbalance of SCM oxygen demand and delivery.

Keywords: Breathing exercise; Central fatigue; Near-infrared spectroscopy; Prefrontal cortex; Respiratory muscle.

MeSH terms

Adult
Breathing Exercises
Dyspnea / metabolism*
Fatigue / metabolism*
Female
Healthy Volunteers
Hemoglobins / metabolism*
Humans
Inhalation / physiology*
Male
Oxygen Consumption / physiology*
Oxyhemoglobins / metabolism*
Prefrontal Cortex / diagnostic imaging
Prefrontal Cortex / metabolism*
Respiratory Muscles / metabolism*
Spectroscopy, Near-Infrared
Young Adult

Substances

Hemoglobins
Oxyhemoglobins
deoxyhemoglobin