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Fictive respiratory rhythm in the isolated brainstem of frogs (1995)

McLean, H. A. ; Kimura, N. ; Kogo, N. ; [et al.]

Springer

Journal of comparative physiology 176 (1995), S. 703-713

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ISSN: 1432-1351

Keywords: Neural control of breathing ; Amphibian ; Isolated brainstem ; Respiration Pattern generation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Spontaneous rhythmically bursting activity was recorded from the trigeminal, vagal and hypoglossal nerve roots of the isolated brainstem from the frogsRana catesbeiana andRana pipiens superfused with a bicarbonate-free HEPES-buffer solution. Burst frequency, burst duration and the activity profile of the spontaneous neural discharges in vitro resembled those of a less radical preparation, the decerebrate, fictively breathing frog. After complete midsagittal section, each half of the isolated brainstem generated its own rhythmic neural activity which resembled that of the intact isolated brainstem. The spontaneous activity generated within each half of the brainstem is probably coordinated by decussating axons or by groups of neurons located along the midline of the brainstem. Our results suggest that these coordinating entities extend the length of the brainstem (in a rostro-caudal dimension) and the degree of contact rather than the location of the contact between the two halves of the brainstem determines the synchronization of the right and left halves. Burst frequency of both the intact and hemisected brainstem preparation was decreased by alkaline challenge and increased by acid challenge. We conclude that this endogeneous rhythmic activity represents the efferent motor output underlying lung ventilation in these animals.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01021590

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Characterization of respiratory-related neurons in the isolated brainstem of the frog (1997)

McLean, H. A. ; Remmers, J. E.

Springer

Journal of comparative physiology 181 (1997), S. 153-159

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ISSN: 1432-1351

Keywords: Key words Amphibian ; Neural control of breathing ; Respiration ; Rhythm generation ; Isolated brainstem

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Using intra- and extracellular recording techniques we examined the spontaneous discharge and membrane properties of respiratory-related neurons in isolated brainstem preparations of the frogs Rana catesbeiana and Rana pipiens that display spontaneous respiratory related activity in vitro. We observed neurons that depolarize during the fictive lung ventilation cycle as well as neurons that depolarize during the non-lung ventilation phase. Respiratory-related neurons demonstrated significant decreases in membrane input resistance during the fictive lung ventilation cycle but showed no evidence of voltage-dependent membrane conductances activated near resting membrane potential. Furthermore, respiratory neurons showed little spike frequency adaptation, their oscillatory activity was not dissociated from the global respiratory motor output following imposed changes in membrane potential, and spontaneous fluctuations in membrane potential were not observed following reversible interruption of respiratory burst activity by application of solutions low in calcium and high in magnesium. Taken together these results suggest that bulbar respiratory neurons in the isolated frog brainstem sampled in our study do not display endogenous bursting characteristics. Rather, they are strongly influenced by synaptic input.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003590050102

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Two regions in the isolated brainstem of the frog that modulate respiratory-related activity (1995)

McLean, H. A. ; Perry, S. F. ; Remmers, J. E.

Springer

Journal of comparative physiology 177 (1995), S. 135-144

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ISSN: 1432-1351

Keywords: Pressure injection ; Neural control of breathing ; Amphibian ; Respiratory rhythmogenesis

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Using microinjection techniques, we have explored the isolated, complete midline sectioned brainstem of the frog (Rana catesbeiana) to identify regions that influence the endogenous respiratory-related motor activity. Ten-nanoliter injections of lidocaine (1%), GABA (100 mM) and glutamate (10 and 100 mM) into discrete regions of the rostral and the caudal brainstem produced different effects on the phasic neural discharge. In the rostral site lidocaine, GABA and glutamate injections altered neural burst frequency with little or no effect on burst amplitude. In the caudal site, responses to lidocaine and GABA injections consisted primarily of decreases in neural burst amplitude, often, but not always associated with minor decreases in burst frequency. In this same region, the response to glutamate was characterized by a temporary interruption of the rhythmic neural burst activity. The largest responses to substance injection in both regions were obtained at sites ranging between 200 and 500 μm from the ventral surface, in the ventral medullary reticular formation. The results reveal the existence of two areas in the frog brainstem that influence respiratory motor output, one related to the respiratory burst frequency and the other related to the amplitude of the motor output.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00225094

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Fictive respiratory rhythm in the isolated brainstem of frogs (1995)

McLean, H. A. ; Kimura, N. ; Kogo, N. ; [et al.]

Springer

Journal of comparative physiology 176 (1995), S. 703-713

add to mindlist on the mindlist

Details

ISSN: 1432-1351

Keywords: Neural control of breathing ; Amphibian ; Isolated brainstem ; Respiration Pattern generation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Spontaneous rhythmically bursting activity was recorded from the trigeminal, vagal and hypoglossal nerve roots of the isolated brainstem from the frogs Rana catesbeiana and Rana pipiens superfused with a bicarbonate-free HEPES-buffer solution. Burst frequency, burst duration and the activity profile of the spontaneous neural discharges in vitro resembled those of a less radical preparation, the decerebrate, fictively breathing frog. After complete midsagittal section, each half of the isolated brainstem generated its own rhythmic neural activity which resembled that of the intact isolated brainstem. The spontaneous activity generated within each half of the brainstem is probably coordinated by decussating axons or by groups of neurons located along the midline of the brainstem. Our results suggest that these coordinating entities extend the length of the brainstem (in a rostro-caudal dimension) and the degree of contact rather than the location of the contact between the two halves of the brainstem determines the synchronization of the right and left halves. Burst frequency of both the intact and hemisected brainstem preparation was decreased by alkaline challenge and increased by acid challenge. We conclude that this endogeneous rhythmic activity represents the efferent motor output underlying lung ventilation in these animals.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00192499

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