The forewing tegulae: their significance in steering manoeuvres and free flight in Locusta migratoria

1998 ◽  
Vol 76 (4) ◽  
pp. 660-667 ◽  
Author(s):  
Christine E Gee ◽  
Kelly L Shoemaker ◽  
R Meldrum Robertson
Keyword(s):  
Muscle Activation ◽  
Locusta Migratoria ◽  
Motor Pattern ◽  
Afferent Input ◽  
Open Loop ◽  
Free Flight ◽  
Flight System ◽  
Depressor Muscle ◽  
Flight Motor

The flight system of Locusta migratoria is widely used to investigate the principles of sensory-motor control. The four tegulae are proprioceptors of the flight system that are active during the downstroke and provide afferent input to flight-system neurons. While the role of the hindwing tegulae in the flight motor pattern has been well characterized, the role of the forewing tegulae is unclear. We tested whether the forewing tegulae may be more important for the generation of intentional steering manoeuvres than for generation of the basic flight motor pattern. Following ablation of the forewing tegulae, tethered flying locusts continued to generate characteristic intentional steering manoeuvres in open-loop conditions. In contrast, we found that locusts were less likely to sustain unrestrained free flight following ablation of the forewing tegulae. We also found that the number of spikes in a forewing depressor muscle increased, as did the hindwing to forewing delay in elevator-muscle activation after ablation of the forewing tegulae. We conclude that the forewing tegulae promote free flight in locusts and we discuss the role they may play in locust flight.

ADAPTIVE MODIFICATIONS IN THE FLIGHT SYSTEM OF THE LOCUST AFTER THE REMOVAL OF WING PROPRIOCEPTORS

1991 ◽  
Vol 157 (1) ◽  
pp. 313-333 ◽  
Author(s):  
ANSGAR BÜSCHGES ◽  
KEIR G. PEARSON
Keyword(s):  
Normal Values ◽  
Locusta Migratoria ◽  
Motor Pattern ◽  
Afferent Input ◽  
Excitatory Input ◽  
Time Dependent ◽  
Intracellular Recordings ◽  
Wingbeat Frequency ◽  
Flight System ◽  
Flight Motor

Previous investigations on the flight system of the locust have found that removal of the wing tegulae in mature locusts (Locusta migratoria) results in an immediate change in the flight motor pattern: the wingbeat frequency (WBF) decreases, the interval between the activity of the depressor and the elevator muscles (the D-E interval) increases, and the phase of the elevator activity in the depressor cycle increases. Here we report the results of a detailed quantitative analysis of these changes. We also examined the flight motor pattern for up to 14 days after removal of the tegulae and found that the changes caused by this operation were not permanent. Beginning on the first day after the operation there was a time-dependent recovery of the WBF, the D-E interval and the phase towards their normal values. In about 80% of the experimental animals the flight motor pattern recovered almost completely. Intracellular recordings from elevator motoneurones showed that this recovery was associated with changes in the pattern of excitatory input to these motoneurones. The modification of activity in elevator motoneurones was dependent on afferent input since complete deafferentation of recovered animals resulted in a motor pattern similar to that following deafferentation of normal animals.

Neural circuits in the flight system of the locust

1985 ◽  
Vol 53 (1) ◽  
pp. 110-128 ◽  
Author(s):  
R. M. Robertson ◽  
K. G. Pearson
Keyword(s):  
Locusta Migratoria ◽  
Motor Pattern ◽  
Short Latency ◽  
Dependent Manner ◽  
Flight System ◽  
Neuronal Connections ◽  
Staining Techniques ◽  
Constant Duration ◽  
To Receive ◽  
Flight Motor

Circuitry in the flight system of the locust, Locusta migratoria, was investigated by use of intracellular recording and staining techniques. Neuronal connections were established by recording simultaneously from neuropile segments of pairs of identified interneurons. Brief depolarizing current pulses delivered to interneurons 301 and 501 reset the flight rhythm in a phase-dependent manner, thus establishing the importance of these neurons in rhythm generation. Interneuron 301 was found to make a strong delayed excitatory connection with 501 and to receive a short-latency inhibitory connection from 501. The circuit formed by 301 and 501 appears suited for promoting rhythmicity in the flight system. The delayed excitatory potential recorded in 501 following each spike of 301 was reversed by hyperpolarizing 501. This potential and short-latency inhibitory postsynaptic potentials from 301 to other interneurons were blocked with the application of picrotoxin. We conclude that the delayed excitation is produced via a disynaptic pathway from 301 to 501, with 301 inhibiting in a graded manner the tonic release of transmitter from one or more unidentified intercalated neurons. Interconnections between the 301-501 circuit and other identified interneurons were discovered. This circuitry can account for two features of the flight motor pattern recorded in deafferented preparations. These features are the constant-latency relationship between depolarizations in elevator and depressor motoneurons and the relatively constant duration of depressor motoneuron bursts. The locust flight system shares general features with other described rhythm-generating systems. These include the occurrence of graded interactions, the probability of multiple oscillatory mechanisms, and a predominance of inhibitory connections. Its uniqueness lies in the way that components and processes are assembled and operate.

Alteration of bursting properties in interneurons during locust flight

1993 ◽  
Vol 70 (5) ◽  
pp. 2148-2160 ◽  
Author(s):  
J. M. Ramirez ◽  
K. G. Pearson
Keyword(s):  
Locusta Migratoria ◽  
Motor Pattern ◽  
Afferent Input ◽  
Proprioceptive Information ◽  
Current Pulses ◽  
Proprioceptive Input ◽  
And Function ◽  
Flight Motor ◽  
Bursting Activity ◽  
Stimulation Of

1. The contribution of bursting properties to the generation of the flight motor pattern was examined for two identified interneurons (interneurons 566 and 567) in the flight system of the locust Locusta migratoria by means of intracellular recording and stimulation techniques. These interneurons are important elements in transmitting proprioceptive information from the hindwing tegula to wing elevator motoneurons. 2. Offset currents injected into these neurons revealed that bursts are triggered in the intact flying animal by synaptic input from tegula afferents (n = 10). These bursts lead to an amplification of proprioceptive input that is crucial for the generation of the intact flight motor pattern. In the absence of afferent input the activity of these neurons remained subthreshold for triggering a burst. This explains why these neurons exhibit only weak rhythmic oscillations in deafferented animals. 3. The property of interneuron 566 to burst was conditional, always being expressed during flight (n = 14) and occurring only occasionally in the quiescent animal. In the absence of flight, stimulation of tegula afferents never evoked bursts in interneuron 566 (n = 7) and depolarizing current pulses evoked weak bursts in only three of nine preparations. In 2 of 14 animals, bursting property of interneuron 566 was enhanced just after the termination of flight. 4. Variability in the bursting property was also found for interneuron 567. In the quiescent animal, tegula-evoked compound excitatory postsynaptic potentials were not sufficient to trigger bursts (n = 3) but depolarizing current pulses evoked always weak rhythmic bursting activity (n = 4). This bursting property was also variable and in one animal we found long-lasting plateau potentials that could be evoked by current injection after flight was elicited several times. 5. The data presented demonstrate that the capacity to burst is conditional in the interneurons 566 and 567. Bursting properties are always induced during flight and function to amplify proprioceptive pathways that are important for the generation of the intact flight motor pattern.

Temperature Dependence of the Neural Control of the Moth Flight System

1970 ◽  
Vol 53 (3) ◽  
pp. 629-639
Author(s):  
JAMES L. HANEGAN ◽  
JAMES EDWARD HEATH
Keyword(s):  
Temperature Dependence ◽  
Neural Control ◽  
Motor Pattern ◽  
Motor Output ◽  
Flight Pattern ◽  
Flight System ◽  
Warm Up ◽  
Thoracic Ganglia ◽  
Flight Motor

1. The transition from the warm-up motor pattern to the flight motor pattern in the saturnid moth H. cecropia, is described. 2. The transition from warm-up to flight was found to be dependent on the temperature of the thoracic ganglia. 3. A model to account for the two different motor output patterns and the transition of the warm-up pattern to the flight pattern is proposed.

Timing of elevator muscle activity during climbing in free locust flight

1999 ◽  
Vol 202 (24) ◽  
pp. 3575-3586 ◽  
Author(s):  
H. Fischer ◽  
W. Kutsch
Keyword(s):  
Muscle Activity ◽  
Closed Loop ◽  
Schistocerca Gregaria ◽  
Motor Pattern ◽  
Detailed Knowledge ◽  
Free Flight ◽  
Flight Muscles ◽  
Flight Motor ◽  
Stroke Amplitude ◽  
Aerodynamic Lift

Despite detailed knowledge of the sensory-motor interactions during elevator muscle timing for the generation of a ‘functional’ flight motor pattern in flying locusts, there is little information about how a possible shift in the onset of elevator activity is correlated with changes in flight variables under closed-loop conditions (i.e. during free flight). Free-flight variables were investigated with respect to ascent angle during climbing flight in locusts Schistocerca gregaria. The motor pattern during free flight was examined by telemetric electromyography of particular antagonistic flight muscles in both ipsilateral hemisegments of the pterothorax while flight variables were recorded simultaneously on video. In the majority of the animals tested, the onset of elevator muscle activity within the wingbeat cycle is delayed when animals increase their ascent angle during climbing flight. In accordance with the motor pattern, the downstroke phase and the stroke amplitude of the wings increased with increasing the ascent angle. This suggests that the relative elevator timing during the wingbeat cycle may be related to the generation of the additional aerodynamic lift required for ascending flight and may, therefore, play a role in the regulation of ascent angle during free flight in the locust.

scholarly journals The role of leg touchdown for the control of locomotor activity in the walking stick insect

2015 ◽  
Vol 113 (7) ◽  
pp. 2309-2320 ◽  
Author(s):  
Joscha Schmitz ◽  
Matthias Gruhn ◽  
Ansgar Büschges
Keyword(s):  
Muscle Activation ◽  
Stance Phase ◽  
Stick Insect ◽  
Afferent Input ◽  
Flexor Muscle ◽  
Locomotor Control ◽  
Burst Intensity ◽  
Stick Insects ◽  
Additional Feedback

Much is known on how select sensory feedback contributes to the activation of different motoneuron pools in the locomotor control system of stick insects. However, even though activation of the stance phase muscles depressor trochanteris, retractor unguis, flexor tibiae and retractor coxae is correlated with the touchdown of the leg, the potential sensory basis of this correlation or its connection to burst intensity remains unknown. In our experiments, we are using a trap door setup to investigate how ground contact contributes to stance phase muscle activation and burst intensity in different stick insect species, and which afferent input is involved in the respective changes. While the magnitude of activation is changed in all of the above stance phase muscles, only the timing of the flexor tibiae muscle is changed if the animal unexpectedly steps into a hole. Individual and combined ablation of different force sensors on the leg demonstrated influence from femoral campaniform sensilla on flexor muscle timing, causing a significant increase in the latencies during control and air steps. Our results show that specific load feedback signals determine the timing of flexor tibiae activation at the swing-to-stance transition in stepping stick insects, but that additional feedback may also be involved in flexor muscle activation during stick insect locomotion. With respect to timing, all other investigated stance phase muscles appear to be under sensory control other than that elicited through touchdown.

scholarly journals Proprioceptive input patterns elevator activity in the locust flight system

1988 ◽  
Vol 59 (6) ◽  
pp. 1831-1853 ◽  
Author(s):  
H. Wolf ◽  
K. G. Pearson
Keyword(s):  
Motor Neuron ◽  
Hind Wing ◽  
Locusta Migratoria ◽  
Motor Pattern ◽  
Afferent Input ◽  
Neuron Activity ◽  
Late Component ◽  
Wingbeat Frequency ◽  
Stretch Receptors ◽  
Receptor Input

1. In the locust, Locusta migratoria, the roles of two groups of wing sense organs, hind wing tegulae and wing-hinge stretch receptors, in the generation of the flight motor pattern were investigated. A preparation was employed that allowed the intracellular recording of neural activity in almost intact tethered flying locusts or after selective manipulations of sensory input. The functions of the two sets of receptors were assessed 1) by studying the phases of their discharges in the wingbeat cycle (Fig. 3), 2) by the selective ablation of input from the receptors (Figs. 4-7), and 3) by the selective stimulation of the receptor afferents (Figs. 8-12). 2. Input from the tegulae was found to be responsible for the initiation of elevator activity (Figs. 9 and 10) and for the generation of a distinct initial rapid depolarization (Figs. 4, 5, and 8) characteristic of elevator motor neuron activity in intact locusts (Figs. 1 and 16). 3. Input from the wing-hinge stretch receptors was found to control the duration of elevator depolarizations by the graded suppression of a second late component of the elevator depolarizations as wingbeat frequency increased (Figs. 6, 7, 11, and 12). The characteristics of this late component of elevator activity suggested that it is generated by the same (central nervous) mechanism that produces the elevator depolarizations recorded in deafferented animals (Fig. 2). Apparently this late component contributes to the intact pattern of elevator depolarizations only at lower wingbeat frequencies and is abolished by the action of stretch-receptor input at frequencies above approximately 15 Hz (Figs. 1, 2, and 4). At these high wingbeat frequencies elevator activity is dominated by the rapid depolarizations generated as a result of tegula input. 4. The present study demonstrates 1) that the timing of elevator motor neuron activity is determined by phasic afferent input from tegulae and stretch receptors and 2) that input from the stretch receptors controls the duration of elevator activity in the wingbeat cycle following the wing movement that was responsible for the generation of the receptor discharge.

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.

Tegula function during free locust flight in relation to motor pattern, flight speed and aerodynamic output

1999 ◽  
Vol 202 (6) ◽  
pp. 711-721 ◽  
Author(s):  
H. Fischer ◽  
E. Ebert
Keyword(s):  
Schistocerca Gregaria ◽  
Motor Pattern ◽  
Flight Speed ◽  
Adaptive Behaviour ◽  
Proprioceptive Information ◽  
Free Flight ◽  
Wingbeat Frequency ◽  
Motor Patterns ◽  
Flight System ◽  
Flight Parameters

Tegulae are complex proprioceptors at the wing base of locusts. Deafferentation of the tegulae causes a lack of specific phasic information related to the wing downstroke and the timing of the upstroke. Employing telemetry during free flight of the locust Schistocerca gregaria, we investigated the consequences of tegula ablation on free flight parameters including motor patterns (wingbeat frequency and the relationship between the activation of flight muscle antagonists), free flight speed and aerodynamic output. We investigated the role of the tegula pairs of both wings on the motor pattern generated in free-flying locusts. We show that the tegula organs are not essential for generating the motor patterns necessary for free flight. However, they are required for increasing the motor output to give additional effective lifting power during adaptive behaviour. We also investigated long-term changes in the free flight parameters after tegula ablation. The recovery of the adult flight system revealed in the present study suggests that there is adaptation to the loss of proprioceptive information; this argues for a full functional and behavioural recovery of the flight system of the locust under closed-loop conditions.

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