Critical Coherence and Characteristic Times in Brain Stem Neuronal Discharge Patterns

1992 ◽  
pp. 525-560 ◽  
Author(s):  
KAREN A. SELZ ◽  
ARNOLD J. MANDELL
1991 ◽  
Vol 01 (03) ◽  
pp. 717-722 ◽  
Author(s):  
KAREN A. SELZ ◽  
ARNOLD J. MANDELL

The binary partition of the range of values for a series of interspike intervals necessary to generate the growth rate of the longest run equivalent to that observed in a Bernoulli, fair coin sequence was found to discriminate three classes of intermittently firing brain stem neurons more clearly than either the higher statistical moments or the leading Lyapunov exponent.


1981 ◽  
Vol 51 (1) ◽  
pp. 204-210 ◽  
Author(s):  
W. M. St John ◽  
D. Bartlett ◽  
K. V. Knuth ◽  
J. C. Hwang

Efferent activities on the phrenic and recurrent laryngeal (RLN) nerves were monitored during eupnea, apneusis, and gasping in decerebrate, paralyzed, and ventilated cats before and after spinal cord transection at the first cervical level. The vagi were sectioned caudal to the RLN being studied and at the midcervical level contralaterally. Before spinal transection, the onset of RLN inspiratory activity preceded that of the phrenic nerve during eupnea and apneusis; in gasping, phrenic activity began before the RLN. These results were the same in normocapnia, hypercapnia, and hypoxia. After spinal transection, no phasic phrenic activity was observed at normoxia or hyperoxia, whereas the RLN exhibited discharge patterns similar to those before transection. Upon end-tidal O2 partial pressure diminutions below 50 Torr, one or more "burst" of phrenic activity were recorded. These bursts were not synchronized with the phasic RLN discharge. It is concluded that automatic ventilatory activity may be generated by inherent brain stem mechanisms. These results further imply the processes underlying gasping neurogenesis may differ fundamentally from those of eupnea or apneusis.


1981 ◽  
Vol 240 (5) ◽  
pp. R335-R347 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber

The relationships among the spontaneous activity of single neurons in the cat medulla and inferior cardiac sympathetic nerve discharge (SND), electroencephalogram (EEG) activity, phrenic nerve activity, and the R wave of the electrocardiogram were studied with the methods of spike-triggered averaging and postevent interval analysis. Three categories of neurons (SR, SE, and S) with activity patterns related to SND wee identified. The activity of SR units was related in time to SND and the R wave but not to EEG activity. SE unit discharges were related to SND and EEG activity but not to the R wave. S unit activity was related only to SND. Each of the three categories of neurons could be subdivided into two groups depending on whether their discharges were followed by an increase or a decrease in SND. All unit types exhibited respiratory-related discharge patterns. These data are discussed with regard to the problems associated with the identification of neurons in brain stem networks that govern the discharges of sympathetic nerves.


1996 ◽  
Vol 76 (1) ◽  
pp. 353-370 ◽  
Author(s):  
C. A. Scudder ◽  
A. K. Moschovakis ◽  
A. B. Karabelas ◽  
S. M. Highstein

1. The discharge patterns and axonal projections of saccadic long-lead burst neurons (LLBNs) with somata in the pontine reticular formation were studied in alert squirrel monkeys with the use of the method of intraaxonal recording and horseradish peroxidase injection. 2. The largest population of stained neurons were afferents to the cerebellum. They originated in the dorsomedial nucleus reticularis tegmenti pontis (NRTP) including its dorsal cell group (N = 5), the preabducens intrafascicular nucleus (N = 5), and the raphe pontis (N = 1). Axons of all neurons coursed under NRTP and entered brachium pontis without having synapsed in the brain stem. Three axons sent collaterals to the floccular lobe, but other more distant targets of these and the other cerebellar afferents could not be determined. Movement fields of these neurons were intermediate between vectorial and directional types. 3. Four neurons had their somata in nucleus reticularis pontis oralis and terminations in the brain stem reticular formation. Each neuron was different, but all terminated in the region containing excitatory burst neurons, and most terminated in the region containing inhibitory burst neurons. Other targets include nucleus reticularis pontis oralis and caudalis, NRTP, raphe interpositus, and the spinal cord. Discharge patterns included both vectorial and directional types. 4. Two reticulospinal neurons had large multipolar somata either just rostral or ventral to the abducens nucleus. These neurons also projected to the medullary reticular formation, caudal nucleus prepositus hypoglossi, and dorsal and ventral paramedian reticular nucleus. 5. The functional implications of the connections of these LLBNs and those reported in the companion paper are extensively discussed. The fact that the efferents of the superior colliculus target the regions containing medium-lead saccadic burst neurons confirms the role of the colliculus in saccade generation. However, the finding that many other neurons project to these regions and the finding that superior colliculus efferents project more heavily to areas containing reticulospinal neurons argue for a diminished role of the superior colliculus in saccade generation but an augmented role in head movement control.


1999 ◽  
Vol 81 (3) ◽  
pp. 1284-1295 ◽  
Author(s):  
James O. Phillips ◽  
Leo Ling ◽  
Albert F. Fuchs

Action of the brain stem saccade generator during horizontal gaze shifts. I. Discharge patterns of omnidirectional pause neurons. Omnidirectional pause neurons (OPNs) pause for the duration of a saccade in all directions because they are part of the neural mechanism that controls saccade duration. In the natural situation, however, large saccades are accompanied by head movements to produce rapid gaze shifts. To determine whether OPNs are part of the mechanism that controls the whole gaze shift rather than the eye saccade alone, we monitored the activity of 44 OPNs that paused for rightward and leftward gaze shifts but otherwise discharged at relatively constant average rates. Pause duration was well correlated with the duration of either eye or gaze movement but poorly correlated with the duration of head movement. The time of pause onset was aligned tightly with the onset of either eye or gaze movement but only loosely aligned with the onset of head movement. These data suggest that the OPN pause does not encode the duration of head movement. Further, the end of the OPN pause was often better aligned with the end of the eye movement than with the end of the gaze movement for individual gaze shifts. For most gaze shifts, the eye component ended with an immediate counterrotation owing to the vestibuloocular reflex (VOR), and gaze ended at variable times thereafter. In those gaze shifts where eye counterrotation was delayed, the end of the pause also was delayed. Taken together, these data suggest that the end of the pause influences the onset of eye counterrotation, not the end of the gaze shift. We suggest that OPN neurons act to control only that portion of the gaze movement that is commanded by the eye burst generator. This command is expressed by driving the saccadic eye movement directly and also by suppressing VOR eye counterrotation. Because gaze end is less well correlated with pause end and often occurs well after counterrotation onset, we conclude that elements of the burst generator typically are not active till gaze end, and that gaze end is determined by another mechanism independent of the OPNs.


2018 ◽  
Vol 119 (2) ◽  
pp. 700-722 ◽  
Author(s):  
Kendall F. Morris ◽  
Sarah C. Nuding ◽  
Lauren S. Segers ◽  
Kimberly E. Iceman ◽  
Russell O’Connor ◽  
...  

We tested the hypothesis that carotid chemoreceptors tune breathing through parallel circuit paths that target distinct elements of an inspiratory neuron chain in the ventral respiratory column (VRC). Microelectrode arrays were used to monitor neuronal spike trains simultaneously in the VRC, peri-nucleus tractus solitarius (p-NTS)-medial medulla, the dorsal parafacial region of the lateral tegmental field (FTL-pF), and medullary raphe nuclei together with phrenic nerve activity during selective stimulation of carotid chemoreceptors or transient hypoxia in 19 decerebrate, neuromuscularly blocked, and artificially ventilated cats. Of 994 neurons tested, 56% had a significant change in firing rate. A total of 33,422 cell pairs were evaluated for signs of functional interaction; 63% of chemoresponsive neurons were elements of at least one pair with correlational signatures indicative of paucisynaptic relationships. We detected evidence for postinspiratory neuron inhibition of rostral VRC I-Driver (pre-Bötzinger) neurons, an interaction predicted to modulate breathing frequency, and for reciprocal excitation between chemoresponsive p-NTS neurons and more downstream VRC inspiratory neurons for control of breathing depth. Chemoresponsive pericolumnar tonic expiratory neurons, proposed to amplify inspiratory drive by disinhibition, were correlationally linked to afferent and efferent “chains” of chemoresponsive neurons extending to all monitored regions. The chains included coordinated clusters of chemoresponsive FTL-pF neurons with functional links to widespread medullary sites involved in the control of breathing. The results support long-standing concepts on brain stem network architecture and a circuit model for peripheral chemoreceptor modulation of breathing with multiple circuit loops and chains tuned by tegmental field neurons with quasi-periodic discharge patterns. NEW & NOTEWORTHY We tested the long-standing hypothesis that carotid chemoreceptors tune the frequency and depth of breathing through parallel circuit operations targeting the ventral respiratory column. Responses to stimulation of the chemoreceptors and identified functional connectivity support differential tuning of inspiratory neuron burst duration and firing rate and a model of brain stem network architecture incorporating tonic expiratory “hub” neurons regulated by convergent neuronal chains and loops through rostral lateral tegmental field neurons with quasi-periodic discharge patterns.


1975 ◽  
Vol 38 (4) ◽  
pp. 751-766 ◽  
Author(s):  
R. W. McCarley ◽  
J. A. Hobson

1. Discharge pattern has been characterized by autocorrelation analysis of stationary portions of extracellularly recorded discharge trains of cat pontine brain stem neurons during spontaneously occurring desynchronized sleep episodes. 2. Neurons localized to the area implicated in control of the desynchronized phase of sleep, the gigantocellular tegmental field (FTG), show the most phasic or clustered discharge pattern, as evinced by initial peaks in the autocorrelations. At the peak, the FTG population average discharge probability is 3 times that expected had the discharges been evenly distributed over time. The initial peak extends beyond a lag of 3 s, indicating runs of clustered discharge extending beyond this duration. Neurons in other reticular tegmental fields, the tegmental reticular nucleus and pontine gray, show a more sustained or tonic discharge pattern. 3. Discharge patterns of a given cell are consistent from one desynchronized sleep episode to the next; units with phasic discharge patterns remain phasic, and tonic patterns remain tonic. 4. There is a three-way correlation among FTG units recorded at sites with many giant cells, units with high discharge rate increases on transition to desynchronized sleep, and units with a markedly phasic discharge pattern. This implicates the giant cells as the source of both the distinctive discharge rate and pattern changes of neurons during desynchronized sleep. 5. Stereotyped, regular discharge patterns are not characteristic of FTG or other units, suggesting they are not pacemakers and that endogenous activation of pacemaker cells is unlikely to be a mechanism for generation of the marked discharge rate increases on transition to desynchronized sleep that are found in FTG units. The irregular, clustered discharge pattern of FTG is more compatible with generation of discharge rate increases through interaction with other cells. The markedly phasic discharge of FTG units is also consistent with a driving role in generation of the phasic electrophysiologic events of desynchronized sleep.


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