Respiratory muscle responses elicited by dorsal periaqueductal gray stimulation in rats

2005 ◽  
Vol 289 (5) ◽  
pp. R1338-R1347 ◽  
Author(s):  
Weirong Zhang ◽  
Linda F. Hayward ◽  
Paul W. Davenport
Keyword(s):  
Gray Matter ◽  
Muscle Activity ◽  
Respiratory Muscle ◽  
Stimulus Frequency ◽  
Periaqueductal Gray ◽  
Emg Activity ◽  
Abdominal Muscles ◽  
Respiratory Response ◽  
Defense Behavior ◽  
Periaqueductal Gray Matter

The periaqueductal gray matter is an essential neural substrate for central integration of defense behavior and accompanied autonomic responses. The dorsal half of the periaqueductal gray matter (dPAG) is also involved in mediating emotional responses of anxiety and fear, psychological states that often are associated with changes in ventilation. However, information regarding respiratory modulation elicited from this structure is limited. The present study was undertaken to investigate the relationship between stimulus frequency and magnitude on ventilatory pattern and respiratory muscle activity in urethane-anesthetized, spontaneously breathing rats. Electrical stimulation in the dPAG-recruited abdominal muscle activity increased ventilation and increased respiratory frequency by significantly shortening both inspiratory time and expiratory time. Ventilation increased within the first breath after the onset of stimulation, and the respiratory response increased with increasing stimulus frequency and magnitude. dPAG stimulation also increased baseline EMG activity in the diaphragm and recruited baseline external abdominal oblique EMG activity, normally quiescent during eupneic breathing. Significant changes in cardiorespiratory function were only evoked by stimulus intensities >10 μA and when stimulus frequencies were >10 Hz. Respiratory activity of both the diaphragm and abdominal muscles remained elevated for a minimum of 60 s after cessation of stimulation. These results demonstrate that there is a short-latency respiratory response elicited from the dPAG stimulation, which includes both inspiratory and expiratory muscles. The changes in respiratory timing suggest rapid onset and sustained poststimulus dPAG modulation of the brain stem respiratory network that includes expiratory muscle recruitment.

Brain stem integration of vocalization: role of the midbrain periaqueductal gray

1994 ◽  
Vol 72 (3) ◽  
pp. 1337-1356 ◽  
Author(s):  
S. P. Zhang ◽  
P. J. Davis ◽  
R. Bandler ◽  
P. Carrive
Keyword(s):  
Muscle Activity ◽  
Sound Production ◽  
Type A ◽  
Periaqueductal Gray ◽  
Emg Activity ◽  
Digastric Muscle ◽  
Type B ◽  
Motor Patterns ◽  
Homocysteic Acid ◽  
Lower Amplitude

1. The contribution of the midbrain periaqueductal gray (PAG) to the central regulation of vocalization was investigated by analyzing the electromyographic (EMG) changes in respiratory, laryngeal, and oral muscles evoked by microinjection of D,L-homocysteic acid (DLH) in the PAG of unanesthetized, precollicular decerebrate cats. Moderate to large (6-40 nmol) doses of DLH evoked natural-sounding vocalization as well as increases in inspiratory depth and respiratory rate. 2. Two basic types of vocalization were evoked, each associated with a distinct and characteristic pattern of respiratory, laryngeal and oral EMG changes. Type A vocalization (voiced sounds such as howl/mew/growl) was characterized by excitation of the cricothyroid (CT) and thyro-arytenoid (TA) muscles, and inhibition of the posterior crico-arytenoid (PCA) muscle, whereas type B vocalization (unvoiced hiss sounds) was characterized by excitation of the PCA and TA muscles and no significant activation of the CT muscle. In addition, stronger expiratory (external oblique, internal oblique, internal intercostal) EMG increases were associated with type A responses, and larger increases in genioglossus and digastric muscle activity were associated with type B responses. 3. Microinjections of small doses of DLH (300 pmol-3 nmol), also evoked patterned changes in muscle activity (usually without audible vocalization) that, although of lower amplitude, were identical to those evoked by injections of moderate to large DLH doses. In no such experiments (175 sites) were individual muscles activated by small dose injections of DLH into the PAG. Further, type A vocalization/muscle patterns were evoked from PAG sites caudal to those at which type B vocalization/muscle patterns were evoked. 4. Considered together these results indicate: that the PAG contains topographically separable groups of neurons that coordinate laryngeal, respiratory, and oral muscle patterns characteristic of two fundamental types of vocalization and that the underlying PAG organization takes the form of a representation of muscle patterns, rather than individual muscles. 5. The patterns of EMG activity evoked by excitation of PAG neurons were strikingly similar to previously reported patterns of EMG activity characteristic of major phonatory categories in higher species, including humans (e.g., vowel phonation, voiceless consonant phonation). These findings raise the possibility that the sound production circuitry of the PAG could well be utilized by cortical and subcortical "language structures" to coordinate basic respiratory and laryngeal motor patterns that are necessary for speech.

Anxiogenic-like effect of glycine and d-serine microinjected into dorsal periaqueductal gray matter of rats

1995 ◽  
Vol 189 (2) ◽  
pp. 93-96 ◽  
Author(s):  
M.L. Schmitt ◽  
W. Coelho ◽  
A.S. Lopes-de-Souza ◽  
F.S. Guimarães ◽  
A.P. Carobrez
Keyword(s):  
Gray Matter ◽  
Periaqueductal Gray ◽  
Periaqueductal Gray Matter ◽  
Dorsal Periaqueductal Gray
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