Summary

Professor:  Part 1 of this post is about the beginning of the time course for symptom awareness:  Within about .015 seconds, less than one breath, the Saliency Network (SN) of our brain can NOTICE something is strange.

Student: At the end of the third of six stages of relatively fast cortical processing, for example, becoming aware of inspiratory load, we will be sending an alert to the Central Executive Network and dampening the Default Mode Network..

Fast Processing

Student: How quickly do we make critical adjustments before we are ‘done in’?

Professor: These adjustments occur within a breath. In fact, both Gozal et al. (1995) and Raux et al. (2013) compared effects of single versus continuous inspiratory loads.

• WITHIN ONE BREATH, Raux et al. showed:
  • increased activity in:
    • insula cortex, the hub of interception integration,
    • thalamus, the final ‘gate’ to higher centers, and other areas, and
  • decreased activity in:
    • cingulate cortex,
    • temporal-occipital junction, and other areas.

Analyzing individual, subcortical, MRI frames was done by Gozal et al. who found:

• AN IMMEDIATE INCREASE in activity of the:
  • parabrachial (Vth motor) nucleus, locus coeruleus,
  • thalamus, putamen, cerebellum (cumen, central vermis, tuber, & uvula), and other areas

• Post respiratory load recovery followed two time courses:
  • immediate decrease, i.e., putamen and cerebellar uvula, or
  • slow signal decrease, i.e., basal forebrain and cerebellar vermis.
• Both studies showed decreasing higher CNS activity for continuous load versus single trial of loading, about which Raux et al. suggested this possibibly shows “cortical automatization secondary to motor learning.”

Student: In fact, the charts are very reminiscent of the blog posts you wrote about the adaptation to split-belt walking, especially the involvement of the cerebellum. For examples and discussion, see:

•  Control-of-leg-timing-vs-placement-during-split-belt-walking, and
• How-does-the-motor-system-correct-walking-errors?

Professor: Very intriguing recollection of yours about the cerebellum, split-belt walking, and adaptation. Actually, the effect of inspiratory load happens within milliseconds: Click here to read more