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Chang EY, Morris KF, Shannon R, Lindsey BG. Repeated sequences of interspike intervals in baroresponsive respiratory related neuronal assemblies of the cat brain stem. J Neurophysiol 2000; 84:1136-48. [PMID: 10979989 DOI: 10.1152/jn.2000.84.3.1136] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many neurons exhibit spontaneous activity in the absence of any specific experimental perturbation. Patterns of distributed synchrony embedded in such activity have been detected in the brain stem, suggesting that it represents more than "baseline" firing rates subject only to being regulated up or down. This work tested the hypothesis that nonrandom sequences of impulses recur in baroresponsive respiratory-related brain stem neurons that are elements of correlational neuronal assemblies. In 15 Dial-urethan anesthetized vagotomized adult cats, neuronal impulses were monitored with microelectrode arrays in the ventral respiratory group, nucleus tractus solitarius, and medullary raphe nuclei. Efferent phrenic nerve activity was recorded. Spike trains were analyzed with cycle-triggered histograms and tested for respiratory-modulated firing rates. Baroreceptors were stimulated by unilateral pressure changes in the carotid sinus or occlusion of the descending aorta; changes in firing rates were assessed with peristimulus time and cumulative sum histograms. Cross-correlation analysis was used to test for nonrandom temporal relationships between spike trains. Favored patterns of interspike interval sequences were detected in 31 of 58 single spike trains; 18 of the neurons with significant sequences also had short-time scale correlations with other simultaneously recorded cells. The number of distributed patterns exceeded that expected under the null hypothesis in 12 of 14 data sets composed of 4-11 simultaneously recorded spike trains. The data support the hypothesis that baroresponsive brain stem neurons operate in transiently configured coordinated assemblies and suggest that single neuron patterns may be fragments of distributed impulse sequences. The results further encourage the search for coding functions of spike patterns in the respiratory network.
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Abstract
This review describes results from in vivo experiments on brain stem network mechanisms that control breathing. Multi-array recording technology and computational methods were used to test predictions derived from simulations of respiratory network models. This highly efficient approach has the advantage that many simultaneously recorded neurons are subject to shared stimulus, history, and state-dependent conditions. Our results have provided evidence for concurrent or parallel network interactions in the generation and modulation of the respiratory motor pattern. Recent data suggest that baroreceptors, chemoreceptors, nociceptors, and airway cough receptors shape the respiratory motor pattern, at least in part, through a system of shared coordinated 'multifunctional' neurons distributed in the brain stem. The 'gravity method' for the analysis and representation of multi-neuron data has demonstrated respiratory phase-dependent impulse synchrony among neurons with no respiratory modulation of their individual firing rates. The detection of this emergent property motivated the development of pattern detection methods that subsequently identified repeated transient configurations of these 'correlational assemblies'. These results support the view that information can be 'coded' in the nervous system by spike timing relationships, in addition to firing rate changes that traditionally have been measured by neurophysiologists.
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Morris KF, Baekey DM, Shannon R, Lindsey BG. Respiratory neural activity during long-term facilitation. RESPIRATION PHYSIOLOGY 2000; 121:119-33. [PMID: 10963769 DOI: 10.1016/s0034-5687(00)00123-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Intermittent hypoxia results in a long-term facilitation (LTF) of respiratory efferent activity. The studies reviewed here presented data from both anesthetized and decerebrate, paralyzed, vagotomized, artificially ventilated adult cats. Multiple arrays of tungsten microelectrodes were used to record the concurrent responses of brain stem neurons that contribute to respiratory motor pattern generation. Spike trains were analyzed with firing rate histograms, peristimulus time histograms, cycle triggered histograms, spike triggered averages with multiunit phrenic efferent activity, cross correlation histograms, joint peristimulus time histograms and the gravity method. These studies addressed several hypotheses. (1) There is parallel processing of input from carotid chemoreceptors to the brain stem. (2) Respiratory related midline neurons are involved in the induction and maintenance of LTF. (3) There is a change in effective connectivity of brain stem neurons with LTF. (4) Neural networks involved in the induction and maintenance of LTF have patterns of synchrony that recur with a frequency greater than expected by chance.
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Hollinger JO, Schmitt JM, Buck DC, Shannon R, Joh SP, Zegzula HD, Wozney J. Recombinant human bone morphogenetic protein-2 and collagen for bone regeneration. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2000; 43:356-64. [PMID: 9855194 DOI: 10.1002/(sici)1097-4636(199824)43:4<356::aid-jbm3>3.0.co;2-7] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The study reported describes a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen (C) to regenerate bone. Unilateral critical-sized defects (CSDs) were prepared in radii of 32 skeletally mature New Zealand white rabbits. Rabbits were divided evenly among four treatments: autograft, absorbable C (Helistat), 35 microg of rhBMP-2 combined with absorbable C (rhBMP-2/C), and untreated CSDs. The two euthanasia periods were 4 and 8 weeks. Radiographs were taken the day of surgery, every 2 weeks, and at term and the percent of radiopacity was measured. Data analysis revealed a time-dependent increase in the percent radiopacity with rhBMP-2/C. Histological examination revealed the rhBMP-2/C treatment regenerated osseous contour by 8 weeks. According to quantitative histomorphometry, the CSD and C groups had significantly less new bone than either autograft or rhBMP-2/C (p < or = 0.05). The results suggest that rhBMP-2/C could be an effective therapy to restore segmental bone defects.
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Arata A, Hernandez YM, Lindsey BG, Morris KF, Shannon R. Transient configurations of baroresponsive respiratory-related brainstem neuronal assemblies in the cat. J Physiol 2000; 525 Pt 2:509-30. [PMID: 10835051 PMCID: PMC2269948 DOI: 10.1111/j.1469-7793.2000.t01-1-00509.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The regulation of gas exchange requires coordination of the respiratory and cardiovascular systems. Previous work suggested that medullary raphe neurones transform and transmit information from baroreceptors to neurones in the ventral respiratory group. This study tested the hypothesis that distributed brainstem neuronal assemblies are transiently reconfigured during the respiratory cycle and baroreceptor stimulation. Blood pressure was perturbed by intravenous injection of an alpha1-adrenergic receptor agonist, unilateral pressure changes in the carotid sinus, or occlusion of the descending aorta in 14 Dial-urethane anaesthetized, vagotomized, paralysed, artificially ventilated cats. Neurones were monitored simultaneously with microelectrode arrays in two or more of the following sites: n. raphe obscurus, n. raphe magnus, rostral and caudal ventrolateral medulla, and the nucleus tractus solitarii. Transient configurations of baroresponsive assemblies were detected with joint pericycle-triggered histograms, the gravitational representation, and related pattern detection methods. Data were also analysed with cycle-triggered histograms, peristimulus-time and cumulative sum histograms, cross-correlograms, spike-triggered averages of efferent phrenic activity, and joint impulse configuration scatter diagrams (snowflakes). Five to nine simultaneously recorded spike trains from control expiratory phases were compared with data from interleaved equal-duration time blocks from control inspiratory phases. In each of seven animals, significant impulse synchrony detected by gravity analysis was confined to one phase of the respiratory cycle. Repeated patterns of distributed synchrony confined to periods of altered baroreceptor activity were detected and involved neurones that individually did not change firing rates during stimulation. Snowflakes and logical cross-correlation analysis provided evidence for the cooperative actions of impulses in concurrently active parallel channels. In 12 of 17 pairs of neurones with at least one baroresponsive cell, joint pericycle-triggered histograms detected synchrony indicative of shared inputs or functional excitatory interactions that varied as a function of time in the respiratory cycle. Neurones in four of the pairs had no respiratory modulation of their individual firing rates. Data from eight other pairs were indicative of fluctuations in inhibition during the respiratory cycle. The results demonstrate repeated transient configurations of baroresponsive neuronal assemblies during the respiratory cycle, without concomitant firing rate changes in the constituent neurones, and suggest distributed network mechanisms for the modulation of baroreceptor-mediated reflexes.
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Shannon R, Baekey DM, Morris KF, Li Z, Lindsey BG. Functional connectivity among ventrolateral medullary respiratory neurones and responses during fictive cough in the cat. J Physiol 2000; 525 Pt 1:207-24. [PMID: 10811738 PMCID: PMC2269920 DOI: 10.1111/j.1469-7793.2000.00207.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
This study tested predictions from a network model of ventrolateral medullary respiratory neurone interactions for the generation of the cough motor pattern observed in inspiratory and expiratory pump muscles. Data were from 34 mid-collicularly decerebrated, paralysed, artificially ventilated cats. Cough-like patterns (fictive cough) in efferent phrenic and lumbar nerve activities were elicited by mechanical stimulation of the intrathoracic trachea. Neurones in the ventral respiratory group, including the Botzinger and pre-Botzinger complexes, were monitored simultaneously with microelectrode arrays. Spike trains were analysed for evidence of functional connectivity and responses during fictive cough with cycle-triggered histograms, autocorrelograms, cross-correlograms, and spike-triggered averages of phrenic and recurrent laryngeal nerve activities. Significant cross-correlogram features were detected in 151 of 1988 pairs of respiratory modulated neurones. There were 59 central peaks, 5 central troughs, 11 offset peaks and 2 offset troughs among inspiratory neurone pairs. Among expiratory neurones there were 23 central peaks, 8 offset peaks and 4 offset troughs. Correlations between inspiratory and expiratory neurones included 20 central peaks, 10 central troughs and 9 offset troughs. Spike-triggered averages of phrenic motoneurone activity had 51 offset peaks and 5 offset troughs. The concurrent responses and multiple short time scale correlations support parallel and serial network interactions proposed in our model for the generation of the cough motor pattern in the respiratory pump muscles. Inferred associations included the following. (a) Excitation of augmenting inspiratory (I-Aug) neurones and phrenic motoneurones by I-Aug neurones. (b) Inhibition of augmenting expiratory (E-Aug) neurones by decrementing inspiratory (I-Dec) neurones. (c) Inhibition of I-Aug, I-Dec and E-Aug neurones by E-Dec neurones. (d) Inhibition of I-Aug and I-Dec neurones and phrenic motoneurones by E-Aug neurones. The data also confirm previous results and support hypotheses in current network models for the generation of the eupnoeic pattern.
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Li Z, Morris KF, Baekey DM, Shannon R, Lindsey BG. Responses of simultaneously recorded respiratory-related medullary neurons to stimulation of multiple sensory modalities. J Neurophysiol 1999; 82:176-87. [PMID: 10400946 DOI: 10.1152/jn.1999.82.1.176] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study addresses the hypothesis that multiple afferent systems share elements of a distributed brain stem network that modulates the respiratory motor pattern. Data were collected from 18 decerebrate, bilaterally vagotomized, paralyzed, artificially ventilated cats. Up to 28 neurons distributed in the rostral and caudal ventral respiratory group, nucleus tractus solitarius, and raphe obscurus were recorded simultaneously with microelectrode arrays. Phases of the respiratory cycle and inspiratory drive were assessed from integrated efferent phrenic nerve activity. Carotid chemoreceptors were stimulated by injection of CO2-saturated saline solution via the external carotid artery. Baroreceptors were stimulated by increased blood pressure secondary to inflation of an embolectomy catheter in the descending aorta. Cutaneous nociceptors were stimulated by pinching a footpad. Four hundred seventy-four neurons were tested for respiratory modulated firing rates and responses; 403 neurons were tested with stimulation of all 3 modalities. Chemoreceptor stimulation and pinch, perturbations that tend to increase respiratory drive, caused similar responses in 52 neurons; 28 responded oppositely. Chemoreceptor and baroreceptor stimulation resulted in similar primary responses in 45 neurons; 48 responded oppositely. Similar responses to baroreceptor stimulation and pinch were recorded for 38 neurons; opposite effects were measured in 26 neurons. Among simultaneously recorded neurons, distinct combinations of firing rate changes were evoked in response to stimulation of the different modalities. The results show a functional convergence of information from carotid chemoreceptors, baroreceptors, and cutaneous nociceptors on respiratory-modulated neurons distributed in the medulla. The data are consistent with the hypothesis that brain stem neurons have overlapping memberships in multifunctional groups that influence the respiratory motor pattern.
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Li Z, Morris KF, Baekey DM, Shannon R, Lindsey BG. Multimodal medullary neurons and correlational linkages of the respiratory network. J Neurophysiol 1999; 82:188-201. [PMID: 10400947 DOI: 10.1152/jn.1999.82.1.188] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study addresses the hypothesis that multiple sensory systems, each capable of reflexly altering breathing, jointly influence neurons of the brain stem respiratory network. Carotid chemoreceptors, baroreceptors, and foot pad nociceptors were stimulated sequentially in 33 Dial-urethan-anesthetized or decerebrate vagotomized adult cats. Neuronal impulses were monitored with microelectrode arrays in the rostral and caudal ventral respiratory group (VRG), nucleus tractus solitarius (NTS), and n. raphe obscurus. Efferent phrenic nerve activity was recorded. Spike trains of 889 neurons were analyzed with cycle-triggered histograms and tested for respiratory-modulated firing rates. Responses to stimulus protocols were assessed with peristimulus time and cumulative sum histograms. Cross-correlation analysis was used to test for nonrandom temporal relationships between spike trains. Spike-triggered averages of efferent phrenic activity and antidromic stimulation methods provided evidence for functional associations of bulbar neurons with phrenic motoneurons. Spike train cross-correlograms were calculated for 6,471 pairs of neurons. Significant correlogram features were detected for 425 pairs, including 189 primary central peaks or troughs, 156 offset peaks or troughs, and 80 pairs with multiple peaks and troughs. The results provide evidence that correlational medullary assemblies include neurons with overlapping memberships in groups responsive to different sets of sensory modalities. The data suggest and support several hypotheses concerning cooperative relationships that modulate the respiratory motor pattern. 1) Neurons responsive to a single tested modality promote or limit changes in firing rate of multimodal target neurons. 2) Multimodal neurons contribute to changes in firing rate of neurons responsive to a single tested modality. 3) Multimodal neurons may promote responses during stimulation of one modality and "limit" changes in firing rates during stimulation of another sensory modality. 4) Caudal VRG inspiratory neurons have inhibitory connections that provide negative feedback regulation of inspiratory drive and phase duration.
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Burgess E, Hollinger J, Bennett S, Schmitt J, Buck D, Shannon R, Joh SP, Choi J, Mustoe T, Lin X, Skalla W, Connors D, Christoforou C, Gruskin E. Charged beads enhance cutaneous wound healing in rhesus non-human primates. Plast Reconstr Surg 1998; 102:2395-403. [PMID: 9858175 DOI: 10.1097/00006534-199812000-00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Enhanced cutaneous wound healing by positively charged cross-linked diethylaminoethyl dextran beads (CLDD) was studied in a standardized incisional wound model in 20 adult and 20 geriatric Macaca mulatta (rhesus) partitioned equally over five time periods. Physiologic saline served as a control. Soft-tissue linear incisions were prepared between and 1 cm inferior to the scapulae. There were four incisions per rhesus; each incision was 1.5 cm long with 1 cm of undisturbed tissue between incisions, and both the experimental CLDD and physiologic saline treatments were administered to each rhesus. The incision treatments were either CLDD and soft-tissue closure with 4-0 BioSyn sutures or sterile physiologic saline and closure with 4-0 BioSyn sutures. The hypothesis was CLDD would enhance cutaneous wound repair. Verification of the hypothesis consisted of clinical examinations and histologic and tensiometric evaluations on biopsy specimens at 10 and 15 days, whereas 5-day and 2- and 4-month groups were assessed clinically and biopsy specimens were assessed histologically. The clinical course of healing for all groups was unremarkable. At 10 days, incisions in adult rhesus treated with CLDD had a 30-percent greater tensile strength compared with the physiologic saline-treated incisions (p = 0.01), whereas for geriatric rhesus, the CLDD treatment proved to be 15 percent greater in tensile strength compared with the physiologic saline cohort (p = 0.11). By day 15, incisions in adult rhesus were 26 percent stronger than the saline treatment group (p = 0.07), and the difference was 36 percent (p = 0.02) for the geriatric rhesus. From 5 through 15 days, histologic observations revealed a gradual decrease in quantity and integrity of CLDD, with no remnants of CLDD at either 2 or 4 months. Macrophages and multinucleated giant cells were localized in the dermis and were associated with the CLDD. These cells decreased commensurately with the decrease of CLDD beads. The data suggest that CLDD can enhance significantly the tensile properties of healing cutaneous wounds in both adult and geriatric rhesus. Moreover, if the wound healing is enhanced in geriatric patients, this finding may be clinically germane to conditions where wound healing is compromised, such as in diabetics and patients on steroids.
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Lindsey BG, Arata A, Morris KF, Hernandez YM, Shannon R. Medullary raphe neurones and baroreceptor modulation of the respiratory motor pattern in the cat. J Physiol 1998; 512 ( Pt 3):863-82. [PMID: 9769428 PMCID: PMC2231246 DOI: 10.1111/j.1469-7793.1998.863bd.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. Perturbations of arterial blood pressure change medullary raphe neurone activity and the respiratory motor pattern. This study sought evidence for actions of baroresponsive raphe neurones on the medullary respiratory network. 2. Blood pressure was perturbed by intravenous injection of an alpha1-adrenergic receptor agonist, unilateral pressure changes in the carotid sinus, or occlusion of the descending aorta in thirty-six Dial-urethane-anaesthetized, vagotomized, paralysed, artificially ventilated cats. Neurones were monitored with microelectrode arrays in two or three of the following domains: nucleus raphe obscurus-nucleus raphe pallidus, nucleus raphe magnus, and rostral and caudal ventrolateral medulla. Data were analysed with cycle-triggered histograms, peristimulus time and cumulative sum histograms, cross-correlograms and spike-triggered averages of efferent phrenic nerve activity. 3. Prolongation of the expiratory phase and decreased peak integrated phrenic amplitude were most frequently observed. Of 707 neurones studied, 310 had altered firing rates during stimulation; changes in opposite directions were monitored simultaneously in fifty-six of eighty-seven data sets with at least two baroresponsive neurones. 4. Short time scale correlations were detected between neurones in 347 of 3388 pairs. Seventeen pairs of baroresponsive raphe neurones exhibited significant offset correlogram features indicative of paucisynaptic interactions. In correlated raphe-ventrolateral medullary neurone pairs with at least one baroresponsive neurone, six of seven ventrolateral medullary decrementing expiratory (E-Decr) neurones increased their firing rate during baroreceptor stimulation. Thirteen of fifteen ventrolateral medullary inspiratory neurones correlated with raphe cells decreased their firing rate during baroreceptor stimulation. 5. The results support the hypothesis that raphe neuronal assemblies transform and transmit information from baroreceptors to neurones in the ventral respiratory group. The inferred actions both limit and promote responses to sensory perturbations and match predictions from simulations of the respiratory network.
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Shannon R, Baekey DM, Morris KF, Lindsey BG. Ventrolateral medullary respiratory network and a model of cough motor pattern generation. J Appl Physiol (1985) 1998; 84:2020-35. [PMID: 9609797 DOI: 10.1152/jappl.1998.84.6.2020] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The primary hypothesis of this study was that the cough motor pattern is produced, at least in part, by the medullary respiratory neuronal network in response to inputs from "cough" and pulmonary stretch receptor relay neurons in the nucleus tractus solitarii. Computer simulations of a distributed network model with proposed connections from the nucleus tractus solitarii to ventrolateral medullary respiratory neurons produced coughlike inspiratory and expiratory motor patterns. Predicted responses of various "types" of neurons (I-DRIVER, I-AUG, I-DEC, E-AUG, and E-DEC) derived from the simulations were tested in vivo. Parallel and sequential responses of functionally characterized respiratory-modulated neurons were monitored during fictive cough in decerebrate, paralyzed, ventilated cats. Coughlike patterns in phrenic and lumbar nerves were elicited by mechanical stimulation of the intrathoracic trachea. Altered discharge patterns were measured in most types of respiratory neurons during fictive cough. The results supported many of the specific predictions of our cough generation model and suggested several revisions. The two main conclusions were as follows: 1) The Bötzinger/rostral ventral respiratory group neurons implicated in the generation of the eupneic pattern of breathing also participate in the configuration of the cough motor pattern. 2) This altered activity of Bötzinger/rostral ventral respiratory group neurons is transmitted to phrenic, intercostal, and abdominal motoneurons via the same bulbospinal neurons that provide descending drive during eupnea.
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Lindsey BG, Morris KF, Shannon R, Gerstein GL. Repeated patterns of distributed synchrony in neuronal assemblies. J Neurophysiol 1997; 78:1714-9. [PMID: 9310455 DOI: 10.1152/jn.1997.78.3.1714] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Models of brain function predict that the recurrence of a process or state will be reflected in repeated patterns of correlated activity. Previous work on medullary raphe assembly dynamics revealed transient changes in impulse synchrony. This study tested the hypothesis that these variations in synchrony include distributed nonrandom patterns of association. Spike trains were recorded simultaneously in the ventrolateral medulla, n. raphe obscurus, and n. raphe magnus of four anesthetized (Dial), vagotomized, paralyzed, and artificially ventilated adult cats. The "gravitational" representation of spike trains was used to detect moments of impulse synchrony in neuronal assemblies visualized as variations in the aggregation velocities of particles corresponding to each neuron. Template matching algorithms were developed to identify excessively repeating patterns of particle condensation rates. Repeating patterns were detected in each animal. The reiterated patterns represented an emergent property not apparent in either corresponding firing rate histograms or conventional gravity representations. Overlapping subsets of neurons represented in different patterns were unmasked when the template resolution was changed. The results demonstrate repeated transient network configurations defined by the tightness and duration of synchrony in different combinations of neurons and suggest that multiple information streams are conveyed concurrently by fluctuations in the synchrony of on-going activity.
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Xu F, Frazier DT, Zhang Z, Baekey DM, Shannon R. Cerebellar modulation of cough motor pattern in cats. J Appl Physiol (1985) 1997; 83:391-7. [PMID: 9262432 DOI: 10.1152/jappl.1997.83.2.391] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cerebellar modulation of cough motor pattern in cats. J. Appl. Physiol. 83(2): 391-397, 1997.-The cerebellum modulates respiratory muscle activity in part via its influence on the central respiratory pattern generator. Because coughing requires well-coordinated respiratory muscle activity, studies were conducted to determine whether the cerebellum influences the centrally generated cough motor pattern. Integrated phrenic and lumbar efferent neurograms (PN and LN, respectively) were monitored in decerebrated, paralyzed, and ventilated cats. Mechanical probing of the intrathoracic trachea was used to evoke fictive coughs; i.e., large increases in PN and LN amplitudes. Cerebellectomy resulted in a decrease in the number of coughs per trial (cough frequency) and LN peak amplitudes without any consistent change in PN peak amplitudes. Cerebellar nuclei [the rostral interposed nucleus (INr) and the rostral fastigial nucleus (FNr)] known to be involved in respiratory control were ablated to determine their potential role in the cough response. Control (eupneic) respiratory frequency was not affected by cerebellectomy or INr/FNr lesions. Cough frequency was depressed by lesion of the INr but not by ablation of the FNr. No significant changes in PN and LN amplitudes were observed after lesion of either the INr or FNr. These results suggest that the cerebellum, specifically the INr, is involved in modulation of the frequency of centrally generated coughing.
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Shannon R, Baekey DM, Morris KF, Lindsey BG. Brainstem respiratory networks and cough. PULMONARY PHARMACOLOGY 1996; 9:343-7. [PMID: 9232673 DOI: 10.1006/pulp.1996.0045] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The focus of this review is work that supports a model of the medullary neuronal network that is involved in producing the cough motor pattern of inspiratory and expiratory pump muscles. Evidence is presented that supports the following hypotheses: (1) Bulbospinal drive to respiratory motoneurons during cough arises, at least in part, from the same medullary neurons involved in providing drive during eupnoea. (2) Medullary Bötzinger/ rostral ventral respiratory group neurons implicated in generating and shaping the eupnoeic pattern of breathing are also involved in producing the central cough motor pattern. The results were not consistent with a "cough centre" separate from the BOT/VRG. Observed neurons (in cats) included most of all previously identified respiratory modulated "types". The results showed that there were alterations in discharge patterns of all respiratory neurons during fictive cough. Many "types" responded as predicted by cough model network simulations. Based on neuron behaviours in our studies and inferred synaptic actions among BOT/VRG neurons, we propose a preliminary model for cough generation by the BOT/rVRG network.
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Morris KF, Arata A, Shannon R, Lindsey BG. Inspiratory drive and phase duration during carotid chemoreceptor stimulation in the cat: medullary neurone correlations. J Physiol 1996; 491 ( Pt 1):241-59. [PMID: 9011617 PMCID: PMC1158775 DOI: 10.1113/jphysiol.1996.sp021212] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. This study addressed the hypothesis that there is a parallel processing of input from carotid chemoreceptors to brainstem neurones involved in inspiratory phase timing and control of inspiratory motor output amplitude. Data were from fifteen anaesthetized, bilaterally vagotomized, paralysed, artificially ventilated cats. Carotid chemoreceptors were stimulated by close arterial injection of 200 microliters of CO2-saturated saline solution. 2. Planar arrays of tungsten microelectrodes were used to monitor simultaneously up to twenty-two neurones in the nucleus tractus solitarii (NTS) and ventral respiratory group (VRG). Spike trains were analysed with two statistical tests of respiratory modulation, cycle-triggered histograms, peristimulus-time histograms, cumulative sum histograms and cross-correlograms. 3. In NTS, 16 of 26 neurones with respiratory and 12 of 27 without respiratory modulation changed firing rate during carotid chemoreceptor stimulation. In the VRG 72 of 112 respiratory and 14 of 48 non-respiratory neurones changed firing rate during stimulation. 4. The spike trains of 85 of 1276 pairs (6.7%) of cells exhibited short time scale correlations indicative of paucisynaptic interactions. Ten pairs of neurones were each composed of a rostral VRG phasic inspiratory neurone that responded to carotid chemoreceptor stimulation with a decline in firing rate and a caudal VRG phasic inspiratory neurone that increased its firing rate. Cross-correlograms from two of the pairs had features consistent with excitation of the caudal neurones by the rostral cells. A decrease in the duration of activity of the rostral VRG neurones was paralleled by the decrease in inspiratory time of phrenic nerve activity. Caudal VRG inspiratory neurones increased their activity as phrenic amplitude increased. Spike-triggered averages of all four neurones indicated post-spike facilitation of phrenic motoneurones. 5. The results support the hypothesis that unilateral stimulation of carotid chemoreceptors results in parallel actions. (a) Inhibition of rostral VRG I-Driver neurones decreases inspiratory duration. (b) Concurrent excitation of premotor VRG and dorsal respiratory group inspiratory neurones increases inspiratory drive to phrenic motoneurones. Other data suggest that responsive ipsilateral neurones act to regulate contralateral neurones.
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Morris KF, Arata A, Shannon R, Lindsey BG. Long-term facilitation of phrenic nerve activity in cats: responses and short time scale correlations of medullary neurones. J Physiol 1996; 490 ( Pt 2):463-80. [PMID: 8821143 PMCID: PMC1158683 DOI: 10.1113/jphysiol.1996.sp021158] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. Stimulation of either peripheral chemoreceptors or nucleus raphe obscurus results in long-term facilitation of phrenic motoneurone activity. The first objective of this work was to measure the concurrent responses of neurones in the nucleus raphe obscurus, the nucleus tractus solitarii, and the regions of the retrofacial nucleus, nucleus ambiguus and nucleus retroambigualis during induction of long-term facilitation. A second goal was to assess functional relationships of the chemoresponsive raphe neurones with neurones in the other monitored locations and with phrenic motoneurones. 2. Up to thirty single medullary neurones and phrenic nerve efferent activity were recorded simultaneously in fifteen anaesthetized, paralysed, vagotomized, artificially ventilated adult cats. Carotid chemoreceptors were stimulated by close arterial injection of 200 microliters of CO2-saturated saline solution. Spike trains were analysed with cycle-triggered histograms and two statistical tests for respiratory modulation. Peristimulus-time histograms and cumulative sum histograms were used to assess responses to stimulation. Cross-correlation was used to test for non-random temporal relationships between spike trains. Spike-triggered average histograms provided evidence for functional associations with phrenic motoneurones. 3. One hundred and thirteen of 348 neurones were monitored in the nucleus raphe obscurus. The firing rates of twenty-nine raphe neurones increased during stimulation; eighteen decreased. In twenty-one pairs of concurrently monitored raphe neurones, the firing rate of one increased its activity during stimulation then decreased, while the other showed an increase that began as the rate of the former declined. Eighteen chemoresponsive raphe neurones had short time scale features in their phrenic spike-triggered averages. Short time scale features were found in cross-correlograms from 184 of 1407 neurone pairs. 4. The data suggest parallel routes by which carotid chemoreceptors influence medullary raphe neurones and support the hypotheses that mid-line respiratory-related neuronal assemblies transform information from those receptors and regulate the gain of respiratory motor output.
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Lindsey BG, Segers LS, Morris KF, Hernandez YM, Saporta S, Shannon R. Distributed actions and dynamic associations in respiratory-related neuronal assemblies of the ventrolateral medulla and brain stem midline: evidence from spike train analysis. J Neurophysiol 1994; 72:1830-51. [PMID: 7823104 DOI: 10.1152/jn.1994.72.4.1830] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. Considerable evidence indicates that neurons in the brain stem midline and ventrolateral medulla participate in the control of breathing. This work was undertaken to detect and evaluate evidence for functional links that coordinate the parallel operations of neurons distributed in these two domains. 2. Data were from 51 Dial-urethan-anesthetized, bilaterally vagotomized, paralyzed, artificially ventilated cats. Planar arrays of tungsten microelectrodes were used to monitor simultaneously spike trains in two or three of the following regions: n. raphe obscurus-n. raphe pallidus, n. raphe magnus, rostral ventrolateral medulla, and caudal ventrolateral medulla. Efferent phrenic nerve activity was recorded to indicate the phases of the respiratory cycle. Electrodes in the ventral spinal cord (C3) were used in antidromic stimulation tests for spinal projections of neurons. 3. Spike trains of 1,243 neurons were tested for respiratory modulated firing rates with cycle-triggered histograms and an analysis of variance with the use of a subjects-by-treatments experimental design. Functional associations were detected and evaluated with cross-correlograms, snowflakes, and the gravity method. 4. Each of 2,310 pairs of neurons studied included one neuron monitored within 0.6 nm of the brain stem midline and a second cell recorded in the ventrolateral medulla; 117 of these pairs (5%) included a neuron with a spinal projection, identified with antidromic stimulation methods, that extended to at least the third cervical segment. Short-time scale correlations were detected in 110 (4.7%) pairs of neurons. Primary cross-correlogram features included 40 central peaks, 47 offset peaks, 4 central troughs, and 19 offset troughs. 5. In 14 data sets, multiple short-time scale correlations were found among three or more simultaneously recorded neurons distributed between both midline and ventrolateral domains. The results suggested that elements of up to three layers of interneurons were monitored simultaneously. Evidence for concurrent serial and parallel regulation of impulse synchrony was detected. Gravitational representations demonstrated respiratory-phase dependent synchrony among neurons distributed in both brain stem regions. 6. The results support a model of the brain stem respiratory network composed of coordinated distributed subassemblies and provide evidence for several hypotheses. 1) Copies of respiratory drive information from rostral ventrolateral medullary (RVLM) respiratory neurons are transmitted to midline neurons. 2) Midline neurons act on respiratory-related neurons in the RVLM to modulate phase timing. 3) Impulse synchrony of midline neurons is influenced by concurrent divergent actions of both midline and ventrolateral neurons.(ABSTRACT TRUNCATED AT 400 WORDS)
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Sant SM, Gilvarry J, Shannon R, O'Morain C. Percutaneous endoscopic gastrostomy--its application in patients with neurological disease. Ir J Med Sci 1993; 162:450-1. [PMID: 8113032 DOI: 10.1007/bf02942186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We performed percutaneous endoscopic gastrostomy (PEG) in 30 patients with prolonged swallowing difficulty (> 4 weeks duration). The average procedure time was 25 minutes. PEG insertion was done on an outpatient basis in four patients. The complication rate was 10% and included failed insertion, peristomal infection and herniation of the gastric mucosa at the gastrostomy exist site. At follow-up, the PEG tube continued to function in 18/22 of the surviving patients with a median in-use time of 85 days. Seven patients died from their original disease. Over a 28-day period, the weight gain among the patients ranged from 3kg to 7kg (mean 4.5kg) and average serum albumin increased from 29g/dl to 35g/dl. This confirms that PEG is a safe, easy and effective method of long-term enteral feeding in patients with neurological disease.
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Goldblum JR, Shannon R, Kaldjian EP, Thiny M, Davenport R, Thompson N, Lloyd RV. Immunohistochemical assessment of proliferative activity in adrenocortical neoplasms. Mod Pathol 1993; 6:663-8. [PMID: 7508113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Although many histologic criteria have been utilized to help distinguish benign from malignant adrenocortical tumors, it still may be difficult to assess the biologic potential of a given tumor. We evaluated 19 adenomas and 15 primary carcinomas with the avidin-biotin complex peroxidase method utilizing formalin-fixed, paraffin-embedded tissues with monoclonal antibodies for proliferating cell nuclear antigen (PC10) and Ki-67 (MIB 1) to determine if staining for these antigens could be used to help differentiate benign from malignant adrenocortical neoplasms. We also evaluated whether these markers could be used as prognostic indicators. Labeling indices for both PCNA and Ki-67 were determined by enumerating 1000 tumor cells, and expressed as a percentage of cells with nuclear staining. A PCNA and a Ki-67 score was obtained by the product of the staining intensity (0-3+) and the extent of nuclear staining, expressed as an estimate of the percentage of cells staining. Both PCNA and Ki-67 score and labeling index were correlated with mitotic counts, histologic diagnosis, and clinical outcome. Follow-up period for patients ranged from 4 months to 12 years with a mean of 25 months. Mitotic counts correlated with histologic diagnosis and clinical outcome. Both Ki-67 score and labeling index were significantly higher in malignant than in benign tumors, and correlated with mitotic counts and clinical outcome. There was a strong correlation between Ki-67 score and labeling index, indicating that Ki-67 score may be a more rapid and equally accurate method of estimating proliferative index of a tumor. PCNA score and labeling index did not correlate with histologic diagnosis or clinical outcome.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
Gastroesophageal reflux is a common occurrence in infancy. The purpose of this article is to describe gastroesophageal reflux and differentiate among its three categories. Initial evaluation includes an accurate history and growth assessment. Continued monitoring of growth is important to determine when and if intervention is necessary. The nurse practitioner will be able to make referrals or prescribe treatment based on the guidelines presented. Having knowledge of the various aspects of this problem will enable the nurse practitioner to assess and monitor the infant and reassure parents.
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Davenport PW, Shannon R, Mercak A, Reep RL, Lindsey BG. Cerebral cortical evoked potentials elicited by cat intercostal muscle mechanoreceptors. J Appl Physiol (1985) 1993; 74:799-804. [PMID: 8458798 DOI: 10.1152/jappl.1993.74.2.799] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Intercostal muscle afferents discharge in response to changes in intercostal muscle mechanics and have spinal and brain stem projections. It was hypothesized that intercostal muscle mechanoreceptors also project to the sensorimotor cortex. In cats, the proximal muscle branch of an intercostal nerve was used for electrical stimulation. The mechanical stimulation was stretch of an isolated intercostal space. The sensorimotor cortex was mapped with a surface ball electrode. Primary cortical evoked potentials (CEP) were found in area 3a of the sensorimotor cortex with mechanical and electrical stimulation. The CEP was elicited with the smallest stretch amplitude used, 50 microns. The CEP response showed little increase beyond 300-microns stretch. The CEP elicited by 50-microns stretch suggests an initial cortical activation by intercostal muscle spindles. The minimal increase in CEP amplitude with stretch > 300 microns suggests that the CEP response is primarily due to muscle spindle recruitment. The increase in amplitude beyond this stretch may be due to recruitment of tendon organs. These results demonstrate a short-latency projection of intercostal muscle mechanoreceptors to the sensorimotor region of the cerebral cortex. This cortical activation may be involved in respiratory sensations and/or transcortical reflex responses to changes in respiratory muscle mechanics.
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Neistadt ME, McAuley D, Zecha D, Shannon R. An analysis of a board game as a treatment activity. Am J Occup Ther 1993; 47:154-60. [PMID: 8470745 DOI: 10.5014/ajot.47.2.154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Occupational therapists often use tabletop board games in treatment to help adult clients with physical disabilities improve the perceptual, cognitive, sensory, and fine motor skill components of occupational behavior. Detailed activity analyses of these types of activities, including performance norms, are not available in the occupational therapy literature. Such analyses would help therapists consider the multiple skill demands of tabletop games and allow more systematic grading of these treatment activities. This paper presents a model for analyzing therapeutic activities in relation to relevant motor learning and cognitive-perceptual literature. Included in this analysis are a description of the activity, examination of its component skills and of the qualitative features of activity performance, suggestions for grading and for treatment goals, and some preliminary performance standards derived from a pilot study of 18 adults without physical disabilities. The issue of transfer of skills between games and functional activities is also discussed.
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Shannon R. More research needed on relationship between GER and apnea. PEDIATRIC NURSING 1992; 18:598-9. [PMID: 1470495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Brannigan A, Williams NN, Grahn M, Williams NS, Fitzpatrick JM, O’Connell PR, Soong CV, Blair P, Halliday MI, Hood JM, Rowlands BJ, D’sa AABB, Cahill RJ, Beattie S, Hamilton H, O’Morain C, Kelly SJ, O’Malley KE, Stack WA, O’Donoghue D, Baird AW, Cronin KJ, Kerin MJ, Crowe J, MacMathuna P, Lennon J, Gorey TF, Chua A, O’Kane V, Dinan TG, Keeling PWN, Mulligan E, Cronin KL, Dervan P, Ireland A, Murphy D, O’Sullivan G, Ryan E, Kelly P, Gilvarry J, Sant S, Fan XJ, Chua A, Shahi CN, O’Connell M, Weir DG, Kelleher D, McDevitt J, O’Donoghue JM, Horgan PG, Byrne WJ, McGuire M, Given HF, Daw MA, Kavanagh P, O’Mahony P, Joy T, Gleeson F, Mullan A, Gibney M, Mannion A, Stevens FM, McCarthy CF, Killeen AA, Murchan PM, Reynolds JV, Leonard N, Marks P, Keane FBV, Tanner WA, O’Connell MA, Corridan B, Collins R, Shannon R, Cahill R, Joyce WP, Goggin M, O’Donoghue D, Hyland J, Traynor O, Qureshi A, DaCosta M, Brindley N, Burke P, Grace P, Bouchier-Hayes D, Leahy AL, Courtney G, Osbome H, O’Donovan N, O’Donoghue M, Collins JK, Morrissey D, McCarthy JE, Redmond HP, Hill ADK, Grace PA, Naama H, Austin OM, Bouchier-Hayes DM, Daly JM, Mulligan E, Fitzpatrick JM, Breslin D, Delaney CP, O’Sullivan ST, O’Sullivan GC, Kirwan WO, Weir CD, McGrath LT, Maynard S, Anderson NH, Halliday MI, D’sa AABB, Gokulan C, O’Gorman TA, Breshihan E, Lam PY, Skehill R, Grimes H, McKeever JA, Stokes MA, Mehigan D, Keaveny TV, Meehan J, Molloy A, Q’Farrelly C, Scott J, Dudeney MS, Leahy A, Grace. PA, McEntee G, Hcaton ND, Douglas V, Mondragon R, O’Grady J, Williams R, Tan KC, Xia HX, Keane CT, O’Morain CA, O’Mahony A, O’Sullivan GC, Corbett A, O’Mahony A, Ireland A, Harte P, Mulcahy H, Patchett S, Stack W, Gallagher M, Connolly K, Doyle J, Flynn JR, Maher M, Hehir D, Horgan A, Stuart R, Brady MP, Johnston PW, Johnston BT, Collins BJ, Collins JSA, Love AHG, Marshall SG, Parks TG, Spence RAJ, O’Connor HJ, Cunnane K, Duggan M, MacMalhuna P, Delaney CP, Kerin M, Gorey TF, Attwood SEA, Viani L, Jeffers M, Walsh TN, Byrne PJ, Frazer I, Hennessy TPJ, Hill GL, Dickey W, McMillan SA, Bharucha C, Porter KG, Rolfe H, Thornton J, Attwood SEA, Coleman J, Stephens RB, Hone S, Holmes K, Kelly IP, Corrigan TP, McCrory D, McCaigue M, Barclay GR, Stack WA, Quirke M, Hegarty JE, O’Donoghue DP, O’Hanlon D, Byrne J. Irish society of gastroenterology. Ir J Med Sci 1992. [DOI: 10.1007/bf02942367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Lindsey BG, Hernandez YM, Morris KF, Shannon R, Gerstein GL. Dynamic reconfiguration of brain stem neural assemblies: respiratory phase-dependent synchrony versus modulation of firing rates. J Neurophysiol 1992; 67:923-30. [PMID: 1588391 DOI: 10.1152/jn.1992.67.4.923] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. The objective of this work was to determine whether configurations of midline brain stem neural assemblies change during the respiratory cycle. 2. Spike trains of several single neurons were recorded simultaneously in anesthetized, paralyzed, bilaterally vagotomized, artificially ventilated cats. Data were analyzed with cross-correlational and gravity methods. 3. Sequential samples from each of eight groups of neurons known to contain synchronously discharging neurons exhibited temporal variations in that synchrony. 4. Gravity analysis of short (less than 200-s) samples of spike train data revealed 20 pairs of clustered particles that were not predicted from cross-correlation analysis of the parent data sets (greater than 20 min). 5. Twenty-nine groups of three to eight simultaneously monitored neurons, each with at least two synchronously discharging neurons, were analyzed for evidence of respiratory phase-dependent modulation of that coordinated activity. Spikes from successive interleaved inspiratory and expiratory intervals were analyzed separately. 6. Neurons pairs in 11 groups were more synchronous during the inspiratory interval; six groups had pairs that were more synchronous during the expiratory period. In two groups, different pairs were synchronous in different respiratory phases. In 11 of the 26 pairs that exhibited phase-dependent differences in synchrony, neither neuron had a respiratory-modulated firing rate as judged by either the cycle-triggered histogram or an analysis of variance of their firing rates. 7. Configurations of respiratory-related brain stem neural networks changed with time and the phases of breathing. Neurons with no apparent respiratory modulation of their individual firing rates collectively exhibited respiratory phase-dependent modulation of their impulse synchrony.(ABSTRACT TRUNCATED AT 250 WORDS)
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