Altered USV pattern in old Tau.P301L mice.

<p>A – Columns in histograms show Freq_(USV) (expressed in kHz) used to produce USV in Tau.P301L (black columns) and FVB/N (white columns) mice at age 4–5 and 8–10 months. Note Freq_(USV) was similar in old Tau.P301L and FVB/N mice. B – As in A, but for RangeFreq ( = max Freq_(USV)−min Freq_(USV), see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0025770#pone-0025770-g001" target="_blank">Fig. 1A2</a>). Note RangeFreq of old Tau.P301L mice was significantly reduced when compared to that of old FVB/N and that of young Tau.P301L mice. C - Columns in histograms show the distribution of totT_(USV) (in %) vs. frequency (Freq), expressed in class of 10 kHz from 30 to 80 kHz in young Tau.P301L and FVB/N at age 4–5 months. Note that most USV used high 50–60 kHz frequency but some used low 30–40 kHz frequency in both genotypes. D – As in C, but for 8–10 months old mice. Arrows highlight that old Tau.P301L mice never used the low 30–40 kHz frequency component in their USV whereas old FVB/N mice still used both low and high frequencies. E - Columns in histograms show the occurrence (%) of USV of different complexity level as defined by the number of segments (see tags in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0025770#pone-0025770-g001" target="_blank">Fig. 1A2</a>) within the USV. Complexity ranged from low (1) to high (5). Note the similar distribution of complexity in Tau.P301L and FVB/N young mice. F – As in E but for old mice. Note the increased occurrence of USV of low complexity and the reduced occurrence of USV of higher complexity (>1) in old Tau.P301L mice compared to old FVB/N and young Tau.P301L mice. Complexity of old FVB/N mice did not change when compared to that of young FVB/N mice. * indicates a significant inter-strain difference at a given class of age and $ a significant age-related difference for a given strain; ns, non significant inter-strain difference.</p

Tauopathy in the PAG of old Tau.P301L mice.

<p>Immunohistochemistry with AT100 as tauopathy marker on midbrain coronal sections of old Tau.P301L mice reveals dramatic tauopathy in the whole PAG, affecting both its caudal (A) and rostral (B) parts. A2, B2 and B3 are enlargements of the dotted line boxes drawn in A1 and B1, and show high density of AT100+ neurons in the caudal, ventro-lateral PAG (A2), the rostral, dorso-median PAG (B2) and the rostral dorso-lateral PAG (B3) of the same old Tau.P301L mouse. B4 shows frequent AT100+ neurons in the rostral, dorso-lateral PAG of another old Tau.P301L mice. Calibration bars: 500 µm for A1, B1; 100 µm for A2, B2–B4.</p

Main USV parameters of young and old Tau.P301L and FVB/N mice.

<p>Mean ± SEM values expressed in ms for Dur_(USV), number USV per min for Nb_(USV), s per min of recording for totT_(USV), kHz for Freq_(USV) and RangeFreq; n, number of studied mice; <i>p</i> values for inter-strain (Tau.P301L vs. FVB/N) and inter-age (young vs. old) comparisons are considered significant when p<0.05.</p

Main breathing parameters of young and old Tau.P301L and FVB/N mice.

<p>Mean ± SEM values expressed in mL/g/s for expiratory airflow (Exp Airflow), cycle per min for respiratory frequency (Rf), and ms for duration of inspiratory (Ti) and expiratory (Te) periods; n, number of studied mice; <i>p</i> values for inter-strain (Tau.P301L vs. FVB/N) and inter-age (young vs. old) comparisons are considered significant when p<0.05.</p

Tauopathy in the NRA and KF areas of old Tau.P301L mice.

<p>Immunohistochemistry with AT100 as tauopathy marker on brainstem coronal sections of a given Tau.P301L mouse (as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0025770#pone-0025770-g004" target="_blank">Fig. 4</a>). Right hand pictures are enlargements of the dotted line boxes drawn in left hand pictures. Sections show that AT100+ neurons are frequent in the NRA (A) and the KF (B) but lacking in the nucleus tractus solitarius and nucleus ambiguus (C). Calibration bars: 500 and 100 µm for left and right hand pictures, respectively. Labels in sections indicate the Kolliker-Fuse nucleus (KF), lateral parabrachial nucleus (LPB), nucleus ambiguus (nA), nucleus tractus solitarius (nTS), hypoglossal motor nucleus (n12), oral pontine reticular nucleus (PnO), principal trigeminal sensory nucleus (Pr5), pyramidal tract (Py), pyramidal decussation (Pyx), superior cerebella peduncle (scp), raphé dorsalis (RD), subcoeruelus nucleus (subC) and intra-medullary rootlet of hypoglossal nerve (12r).</p

Summary diagram of the organization of the PAG, KF and NRA network controlling vocalization.

<p>Arrows indicate the demonstrated connections between structures controlling vocalization and numbers within arrows the related publications in the reference list. Mn, motor neurons; A6, locus coeruleus; RVLM, rostral ventrolateral medulla.</p

Altered USV production in old Tau.P301L mice.

<p>A1- Rough USV spectrographic display with frequency and time scales in kHz and ms, respectively. A2 – As above but showing the tags (Tg, white dots) placed at slope changes in frequency on the rough USV and the analyzed USV parameters: duration of USV (Dur_(USV)), frequency at tags (Freq_(USV)), max and min Freq_(USV) (RangeFreq), complexity (number of segments delimited by tags), and number of USV produced per min of recording (Nb_(USV)). The total time of USV per min (totT_(USV)) was obtained by summation of individual Dur_(USV). B – Columns in histograms show Dur_(USV) (expressed in ms) in Tau.P301L (black columns) and FVB/N (white columns) mice at age 4–5 months and 8–10 months (young and old mice, respectively). Note the significant reduction of Dur_(USV) in old Tau.P301L mice. C – As in B but for Nb_(USV) (expressed in USV per min). Note the drastic reduction of Nb_(USV) in old Tau.P301L mice. D – As in B but totT_(USV) (expressed in s per min of recording). Note the significant and drastic reduction of totT_(USV) in old Tau.P301L mice. * indicates a significant inter-strain difference at a given class of age and $ a significant age-related difference for a given strain; ns, non significant inter-strain difference.</p

Reduced expiratory airflow in old Tau.P301L mice.

<p>A - Schematic presentation of the double-chamber plethysmographic set-up allowing the simultaneous recordings of chest spirogram (CSp; in the body chamber) and airflow spirogram (ASp; in the head chamber) in conscious mice. B, C – Averaging of about 100 successive respiratory cycles during quiet period of breathing in young (B) and old (C) mice allowed the measurements of mean ASp and CSp, the calculation of the ASp/CSp ratio and the measurement of expiratory airflow during lung emptying period (gray areas). D - Columns in histograms show the ASp/CSp ratio in Tau.P301L (black columns) and FVB/N (white columns) young and old mice. Note 1) the ratio was similar in young Tau.P301L and FVB/N mice, and 2) the ratio was significantly reduced and increased in old Tau.P301L and FVB/N mice, respectively. E – As in D but for the expiratory airflow. Note the expiratory airflow was similar in young Tau.P301L and FVB/N mice, significantly halved in old Tau.P301L mice and unchanged in old FVB/N mice. * indicates a significant inter-strain difference at a given class of age and $ a significant age-related difference for a given strain; ns, non significant inter-strain difference.</p

Table_2_Central Respiration and Mechanical Ventilation in the Gating of Swallow With Breathing.xlsx

<p>Swallow-breathing coordination safeguards the lower airways from tracheal aspiration of bolus material as it moves through the pharynx into the esophagus. Impaired movements of the shared muscles or structures of the aerodigestive tract, or disruptions in the interaction of brainstem swallow and respiratory central pattern generators (CPGs) result in dysphagia. To maximize lower airway protection these CPGs integrate respiratory rhythm generation signals and vagal afferent feedback to synchronize swallow with breathing. Despite extensive study, the roles of central respiratory activity and vagal feedback from the lungs as key elements for effective swallow-breathing coordination remain unclear. The effect of altered timing of bronchopulmonary vagal afferent input on swallows triggered during electrical stimulation of the superior laryngeal nerves or by injection of water into the pharyngeal cavity was studied in decerebrate, paralyzed, and artificially ventilated cats. We observed two types of single swallows that produced distinct effects on central respiratory-rhythm across all conditions: post-inspiratory type swallows disrupted central-inspiratory activity without affecting expiration, whereas expiratory type swallows prolonged expiration without affecting central-inspiratory activity. Repetitive swallows observed during apnea reset the E2 phase of central respiration and produced facilitation of swallow motor output nerve burst durations. Moreover, swallow initiation was negatively modulated by vagal feedback and was reset by lung inflation. Collectively, these findings support a novel model of reciprocal inhibition between the swallow CPG and inspiratory or expiratory cells of the respiratory CPG where lung distension and phases of central respiratory activity represent a dual peripheral and central gating mechanism of swallow-breathing coordination.</p