Regional Cerebrovascular Responses to Hypercapnia and Hypoxia.

A limited number of studies using differing imaging approaches suggest that there are regional variation in the cerebrovascular response to hypercapnia and hypoxia. However there are limitations to these studies. In particular, it is not clear if existing studies of hypoxia have fully accounted for the confounding effects of the changes in arterial PCO2 on cerebral perfusion that, if uncontrolled, will accompany the hypoxic stimulus.

Sub-cortical and brainstem sites associated with chemo-stimulated increases in ventilation in humans.

We investigated the neural basis for spontaneous chemo-stimulated increases in ventilation in awake, healthy humans. Blood oxygen level dependent (BOLD) functional MRI was performed in nine healthy subjects using T2 weighted echo planar imaging. Brain volumes (52 transverse slices, cortex to high spinal cord) were acquired every 3.

Unilateral ablation of pre-Botzinger complex disrupts breathing during sleep but not wakefulness.

Rationale: In adult rats, bilateral ablation of pre-Bötzinger complex (preBötC) neurokinin 1-expressing (NK1R) neurons leads to a progressive and irreversible disruption in breathing pattern, initially during sleep, eventually resulting in an ataxic breathing pattern during wakefulness.

Objectives: Here we determine whether ablation of fewer preBötC NK1R neurons leads to a persistent pattern of disordered breathing during sleep but not during wakefulness.

Methods: Adult male Sprague-Dawley rats (n = 12) were instrumented to record diaphragmatic, abdominal, and neck EMG, and EEG.

A bilateral cortico-bulbar network associated with breath holding in humans, determined by functional magnetic resonance imaging.

Few tasks are simpler to perform than a breath hold; however, the neural basis underlying this voluntary inhibitory behaviour, which must suppress spontaneous respiratory motor output, is unknown. Here, using blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI), we investigated the neural network responsible for volitional breath holding in 8 healthy humans. BOLD images of the whole brain (156 brain volumes, voxel resolution 3x3x3 mm) were acquired every 5.

Sleep-disordered breathing after targeted ablation of preBötzinger complex neurons.

Ablation of preBötzinger complex (preBötC) neurons, critical for respiratory rhythm generation, resulted in a progressive, increasingly severe disruption of respiratory pattern, initially during sleep and then also during wakefulness in adult rats. Sleep-disordered breathing is highly prevalent in elderly humans and in some patients with neurodegenerative disease. We propose that sleep-disordered breathing results from loss of preBötC neurons and could underlie death during sleep in these populations.

Episodic hypoxia evokes long-term facilitation of genioglossus muscle activity in neonatal rats.

The aim of this study was to determine if episodic hypoxia evokes persistent increases of genioglossus muscle (GG) activity, termed long-term facilitation (LTF), in neonatal rats in vivo. Experiments were performed on anaesthetized, spontaneously breathing, intubated neonatal rats (postnatal days (P) 3-7), divided into three groups. The first group (n= 8) was subjected to three 5-min periods of hypoxia (5% O(2)-95% N(2)) alternating with 5 min periods of room air.