Schematic representation of the method used to identify pre-inspiratory potentials from the raw EEG signal and the ventilatory flow signal.

<p>(Adapted from Raux et al., <i>Anesthesiology</i>—<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084534#pone.0084534-Raux3" target="_blank">[19]</a>—with permission from the authors and the publisher.) Artwork Robin Jacqueline. The EEG signal is segmented in epochs defined according to the ventilatory flow signal (1). These epochs are ensemble averaged (2). The resulting signal is inspected visually for a putative pre-inspiratory potential (3) of which the presence is ascertained through the calculation of a linear regression over the region of interest and comparison of the slope of this regression with 0. See “<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084534#s2" target="_blank">Methods</a>” for details. Pre-inspiratory potentials and the related motor potentials are normally absent during quiet breathing.</p

Average pre-inspiratory EEG tracings in one of the congenital central hypoventilation syndrome patient.

<p>In each of the panels, the top trace depicts the Cz-EEG signal, and the bottom trace depicts ventilatory flow. The vertical line indicates the onset of inspiration. In the “inspiratory threshold loading” panel, inspiration is preceded by a shift upward of the EEG trace (horizontal double arrowed red line) that is characteristic of a pre-inspiratory potential. This observation is similar to that made in normal individuals <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084534#pone.0084534-Raux1" target="_blank">[12]</a>. In contrast to normal individuals however, a pre-inspiratory potential can also be seen, abnormally, in the three “control condition” panels (control 1: resting ventilation with minimal constraint, namely a respiratory inductance plethysmography vest only; control 2: resting ventilation while breathing through a pneumoatchograph; control 3: as control 2, but during the washout period following inspiratory loading) and in the “CO₂ stimulated breathing” panel.</p

Average pre-inspiratory EEG tracings in one of the control subjects.

<p>In each of the panels, the top trace depicts the Cz-EEG signal, and the bottom trace depicts ventilatory flow. The vertical line indicates the onset of inspiration. In the three “control condition” panels (control 1: resting ventilation with minimal constraint, namely a respiratory inductance plethysmography vest only; control 2: resting ventilation while breathing through a pneumoatchograph; control 3: as control 2, but during the washout period following inspiratory loading), inspiration is not preceded by any change in the EEG signal (absence of pre-inspiratory potentials). In the “CO₂ stimulated breathing” panel, inspiration is also not preceded by any change in the EEG signal (absence of pre-inspiratory potentials). In contrast, in the “inspiratory threshold loading” panel, inspiration is preceded by a shift upward of the EEG trace (horizontal double arrowed red line) that is characteristic of a pre-inspiratory potential. This pattern exactly corresponds to what is expected in normal individuals <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084534#pone.0084534-Raux1" target="_blank">[12]</a>.</p

Individual example of a patient with congenital muscular dystrophy of unknown origin showing only the N1 component of the respiratory related evoked potential following inspiratory airway occlusion

<p><b>Copyright information:</b></p><p>Taken from "Impaired cortical processing of inspiratory loads in children with chronic respiratory defects"</p><p>http://respiratory-research.com/content/8/1/61</p><p>Respiratory Research 2007;8(1):61-61.</p><p>Published online 6 Sep 2007</p><p>PMCID:PMC2020473.</p><p></p> The P1 component is not reproducible. Traces represent from top to bottom: left (C-C) response, right (C-C) response, and real time mouth pressure. S: onset of occlusion stimulus

The Cerebral Cost of Breathing: An fMRI Case-Study in Congenital Central Hypoventilation Syndrome

<div><p>Certain motor activities - like walking or breathing - present the interesting property of proceeding either automatically or under voluntary control. In the case of breathing, brainstem structures located in the medulla are in charge of the automatic mode, whereas cortico-subcortical brain networks - including various frontal lobe areas - subtend the voluntary mode. We speculated that the involvement of cortical activity during voluntary breathing could impact both on the “resting state” pattern of cortical-subcortical connectivity, and on the recruitment of executive functions mediated by the frontal lobe. In order to test this prediction we explored a patient suffering from central congenital hypoventilation syndrome (CCHS), a very rare developmental condition secondary to brainstem dysfunction. Typically, CCHS patients demonstrate efficient cortically-controlled breathing while awake, but require mechanically-assisted ventilation during sleep to overcome the inability of brainstem structures to mediate automatic breathing. We used simultaneous EEG-fMRI recordings to compare patterns of brain activity between these two types of ventilation during wakefulness. As compared with spontaneous breathing (SB), mechanical ventilation (MV) restored the default mode network (DMN) associated with self-consciousness, mind-wandering, creativity and introspection in healthy subjects. SB on the other hand resulted in a specific increase of functional connectivity between brainstem and frontal lobe. Behaviorally, the patient was more efficient in cognitive tasks requiring executive control during MV than during SB, in agreement with her subjective reports in everyday life. Taken together our results provide insight into the cognitive and neural costs of spontaneous breathing in one CCHS patient, and suggest that MV during waking periods may free up frontal lobe resources, and make them available for cognitive recruitment. More generally, this study reveals how the active maintenance of cortical control over a continuous motor activity impacts on brain functioning and cognition.</p></div

Individual example of a patient with Duchenne muscular dystrophy showing the 4 components of the respiratory related evoked potential following inspiratory airway occlusion

<p><b>Copyright information:</b></p><p>Taken from "Impaired cortical processing of inspiratory loads in children with chronic respiratory defects"</p><p>http://respiratory-research.com/content/8/1/61</p><p>Respiratory Research 2007;8(1):61-61.</p><p>Published online 6 Sep 2007</p><p>PMCID:PMC2020473.</p><p></p> Traces represent from top to bottom: left (C-C) response, right (C-C) response, and real time mouth pressure. S: onset of occlusion stimulus

Functional MR connectivity assessed with an ICA method.

<p>(A).Default mode network (DMN): bilateral medial prefrontal and anterior cingulate cortices (1), bilateral precuneus (2), bilateral superior parietal cortices (3). (B).Mean values ± standard deviation of DMN integrations for the mechanical (MV) and the spontaneous (SB) breathing blocks of resting state. The asterisk indicates a significant difference between conditions. (C). Sensorimotor network (SMN): bilateral supplementary motor area (1) and bilateral sensorimotor cortices (2). (D).Mean values ± standard deviation of SMN integrations for the mechanical (MV) and the spontaneous (SB) breathing blocks of resting state. NS  =  non-significant difference between conditions; AU  =  arbitrary unit.</p

Stability of wakefulness under MV and SB indexed by EEG.

<p>(A). Scalp voltage topographies of alpha power (up) and theta (bottom) averaged across the 4 EEG-fMRI sessions reveal a typical pattern of wakefulness characterized by a high posterior alpha power and a low anterior mid-frontal power. (B). Dynamics of the (posterior alpha power)/(mid-frontal theta power) ration is plotted across time for the 4 EEG-fMRI sessions. This index of wakefulness was stable across the 4 sessions, and confirmed a stable level of wakefulness all along the fMRI experiments, with no difference between SB and MV.</p

Synthesis of fMRI results.

<p>Synthesis of fMRI results.</p

Restoration of DMN under mechanical ventilation.

<p>(A). Comparison of BOLD signal between MV and SB revealed a specific increase of activation in the default-mode network associated in awake controls in introspection and self-consciousness. No significant result was observed in the opposite contrast. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107850#pone-0107850-t001" target="_blank">Table 1</a> for detailed fMRI results. (B&C). Functional connectivity assessed with a hypothesis-driven approach revealed a larger correlation with precuneus activity in posterior mesial areas during MV than during SB (B), and a larger correlation between brainstem activity and a large anterior cortico-subcortical network during SB than during MV (C). This large network resembles the executive attention network.</p