Chemical deafferentation of the locust flight system by phentolamine

1990 ◽  
Vol 167 (4) ◽  
Author(s):  
J.M. Ramirez ◽  
K.G. Pearson
Keyword(s):  
Flight System ◽  
Locust Flight ◽  
Chemical Deafferentation

Connections of the forewing tegulae in the locust flight system and their modification following partial deafferentation

1992 ◽  
Vol 23 (1) ◽  
pp. 44-60 ◽  
Author(s):  
Ansgar Büschges ◽  
Jan-Marino Ramirez ◽  
Robert Driesang ◽  
Keir G. Pearson
Keyword(s):  
Flight System ◽  
Locust Flight

Effects of temperature on synaptic potentials in the locust flight system

1993 ◽  
Vol 70 (6) ◽  
pp. 2197-2204 ◽  
Author(s):  
R. M. Robertson
Keyword(s):  
Room Temperature ◽  
Synaptic Function ◽  
Membrane Properties ◽  
Excitatory Postsynaptic Potential ◽  
Channel Conductance ◽  
Flight System ◽  
Epsp Amplitude ◽  
Time To Peak ◽  
Locust Flight ◽  
Effects Of Temperature

1. Neuronal circuitry in the locust flight system operates normally within a temperature range of 24-42 degrees C. I investigated the effects of temperature on parameters of postsynaptic potentials generated in different neurons following action potentials of the forewing stretch receptor. 2. Increases in temperature reduced latency, time-to-peak and duration (Q10s = 0.51, 0.70, and 0.68, respectively; 24–34 degrees C) and increased the slope (Q10 = 1.13; 24-34 degrees) of the excitatory postsynaptic potential (EPSP). However, increases in temperature increased EPSP amplitude below room temperature (Q10 = 1.25; 14–24 degrees C) but decreased EPSP amplitude above room temperature (Q10 = 0.80; 24–34 degrees C). 3. I conclude that neuronal and synaptic function were affected by temperature in ways predictable by well-established thermal effects on channel conductance and kinetics and on membrane properties. Thus temperature compensation of the output of the flight system must be mediated in some way by the operation of the circuitry. 4. I propose that below room temperature EPSP amplitude was increased by predominant effects on channel conductance and membrane time constant, and above room temperature EPSP amplitude was decreased by a predominant effect on the amplitude and duration of the presynaptic action potential. Further, I suggest that the frequency of the output rhythm is unaffected by the amplitude of single EPSPs, within permissive limits.

Plasticity of Synaptic Connections in Sensory-Motor Pathways of the Adult Locust Flight System

1997 ◽  
Vol 78 (3) ◽  
pp. 1276-1284 ◽  
Author(s):  
Harald Wolf ◽  
Ansgar Büschges
Keyword(s):  
Electric Stimulation ◽  
Motor Pattern ◽  
Competitive Interactions ◽  
Synaptic Connections ◽  
Flight System ◽  
Motor Pathways ◽  
Synaptic Contacts ◽  
Locust Flight ◽  
Sensory Motor ◽  
Adult Locust

Wolf, Harald and Ansgar Büschges. Plasticity of synaptic connections in sensory-motor pathways of the adult locust flight system. J. Neurophysiol. 78: 1276–1284, 1997. We investigated possible roles of retrograde signals and competitive interactions in the lesion-induced reorganization of synaptic contacts in the locust CNS. Neuronal plasticity is elicited in the adult flight system by removal of afferents from the tegula, a mechanoreceptor organ at the base of the wing. We severed one hindwing organ and studied the resulting rearrangement of synaptic contacts between flight interneurons and afferent neurons from the remaining three tegulae (2 forewing, 1 hindwing). This was done by electric stimulation of afferents and intracellular recording from interneurons (and occasionally motoneurons). Two to three weeks after unilateral tegula lesion, connections between tegula afferents and flight interneurons were altered in the following way. 1) Axons from the forewing tegula on the operated side had established new synaptic contacts with metathoracic elevator interneurons. In addition, the amplitude of compound excitatory postsynaptic potentials elicited by electric stimulation was increased, indicating that a larger number of afferents connected to any given interneuron. 2) On the side contralateral to the lesion, connectivity between axons from the forewing tegula and elevator interneurons was decreased. 3) The efficacy of the (remaining) hindwing afferents appeared to be increased with regard to both synaptic transmission to interneurons and impact on flight motor pattern. 4) Flight motoneurons, which are normally restricted to the ipsilateral hemiganglion, sprouted across the ganglion midline after unilateral tegula removal and apparently established new synaptic contacts with tegula afferents on that side. The changes on the operated side are interpreted as occupation of synaptic space vacated on the interneurons by the severed hindwing afferents. On the contralateral side, the changes in synaptic contact must be elicited by retrograde signals from bilaterally arborizing flight interneurons, because tegula projections remain strictly ipsilateral. The pattern of changes suggests competitive interactions between forewing and hindwing afferents. The present investigation thus presents evidence that the CNS of the mature locust is capable of extensive synaptic rearrangement in response to injury and indicates for the first time the action of retrograde signals from interneurons.

Phase-Dependent Presynaptic Modulation of Mechanosensory Signals in the Locust Flight System

1999 ◽  
Vol 81 (2) ◽  
pp. 959-962 ◽  
Author(s):  
Ansgar Büschges ◽  
Harald Wolf
Keyword(s):  
Membrane Potential ◽  
Input Resistance ◽  
Inhibitory Input ◽  
Flight System ◽  
Presynaptic Modulation ◽  
Locust Flight ◽  
Presynaptic Mechanisms ◽  
Flight Motor ◽  
Afferent Signaling ◽  
Presynaptic Control

Phase-dependent presynaptic modulation of mechanosensory signals in the locust flight system. In the locust flight system, afferents of a wing hinge mechanoreceptor, the hindwing tegula, make monosynaptic excitatory connections with motoneurons of the elevator muscles. During flight motor activity, the excitatory postsynaptic potentials (EPSPs) produced by these connections changed in amplitude with the phase of the wingbeat cycle. The largest changes occurred around the phase where elevator motoneurons passed through their minimum membrane potential. This phase-dependent modulation was neither due to flight-related oscillations in motoneuron membrane potential nor to changes in motoneuron input resistance. This indicates that modulation of EPSP amplitude is mediated by presynaptic mechanisms that affect the efficacy of afferent synaptic input. Primary afferent depolarizations (PADs) were recorded in the terminal arborizations of tegula afferents, presynaptic to elevator motoneurons in the same hemiganglion. PADs were attributed to presynaptic inhibitory input because they reduced the input resistance of the afferents and were sensitive to the γ-aminobutyric acid antagonist picrotoxin. PADs occurred either spontaneously or were elicited by spike activity in the tegula afferents. In summary, afferent signaling in the locust flight system appears to be under presynaptic control, a candidate mechanism of which is presynaptic inhibition.

Anoxia induces thermotolerance in the locust flight system

2002 ◽  
Vol 205 (6) ◽  
pp. 815-827 ◽  
Author(s):  
B. S. Wu ◽  
J. K. Lee ◽  
K. M. Thompson ◽  
V. K. Walker ◽  
C. D. Moyes ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Heat Shock ◽  
Temperature Stress ◽  
High Temperature Stress ◽  
Cross Tolerance ◽  
Flight System ◽  
Locust Flight ◽  
Induced Thermotolerance ◽  
K Currents

SUMMARYHeat shock and anoxia are environmental stresses that are known to trigger similar cellular responses. In this study, we used the locust to examine stress cross-tolerance by investigating the consequences of a prior anoxic stress on the effects of a subsequent high-temperature stress. Anoxic stress and heat shock induced thermotolerance by increasing the ability of intact locusts to survive normally lethal temperatures. To determine whether induced thermotolerance observed in the intact animal was correlated with electrophysiological changes, we measured whole-cell K+ currents and action potentials from locust neurons. K+ currents recorded from thoracic neuron somata were reduced after anoxic stress and decreased with increases in temperature. Prior anoxic stress and heat shock increased the upper temperature limit for generation of an action potential during a subsequent heat stress. Although anoxia induced thermotolerance in the locust flight system, a prior heat shock did not protect locusts from a subsequent anoxic stress. To determine whether changes in bioenergetic status were implicated in whole-animal cross-tolerance, phosphagen levels and rates of mitochondrial respiration were assayed. Heat shock alone had no effect on bioenergetic status. Prior heat shock allowed rapid recovery after normally lethal heat stress but afforded no protection after a subsequent anoxic stress. Heat shock also afforded no protection against disruption of bioenergetic status after a subsequent exercise stress. These metabolite studies are consistent with the electrophysiological data that demonstrate that a prior exposure to anoxia can have protective effects against high-temperature stress but that heat shock does not induce tolerance to anoxia.

Recovery of the flight system following ablation of the tegulae in immature adult locusts

1996 ◽  
Vol 199 (6) ◽  
pp. 1395-1403 ◽  
Author(s):  
C Gee ◽  
R Robertson
Keyword(s):  
Locusta Migratoria ◽  
Motor Pattern ◽  
Recovery Period ◽  
Wingbeat Frequency ◽  
Mature Adult ◽  
Flight System ◽  
Mature Adults ◽  
Locust Flight ◽  
Adult Locust ◽  
The Individual

The capacity of the flight system to recover from ablation of the tegulae was studied in immature adult Locusta migratoria and compared with recovery in mature adults. We ablated the hindwing tegulae or all tegulae in adult locusts either 1 day after the imaginal moult (immature locusts) or 2 weeks after the imaginal moult (mature locusts). We monitored recovery throughout the recovery period by using a stroboscope to measure the wingbeat frequency of tethered locusts. In addition, we measured other parameters of the flight motor pattern using electromyographic electrodes implanted into recovered locusts. Both methods of monitoring recovery yielded the same results. There was no reduction, during adult maturation, in the capacity of the locust flight system to recover from the loss of these proprioceptors. Plasticity of the locust flight system was therefore maintained in the mature adult locust. This suggests that the flight system is not fixed and simply implemented when the locust reaches adulthood, but that the circuitry can be remodelled throughout the animal's life to produce behaviour adapted to the needs and constraints of the individual.

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