Modulation of auditory responsiveness in the locust

Boyan, George

doi:10.1007/bf01324823

Cited by 14 publications

(4 citation statements)

References 39 publications

(49 reference statements)

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“…This neuron's structure is obviously homologous to the AN4-neuron described in Locusta migratoria (compare Fig. 2a and b; see also R6mer and Marquart 1984; synonymous: neuron 541, Boyan 1986). We will use the term AN4 for Ch.…”

Section: Interneuron Morphologysupporting

confidence: 54%

Filtering of behaviourally relevant temporal parameters of a grasshopper's song by an auditory interneuron

Ronacher

Stumpner

1988

J. Comp. Physiol.

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In females of the acridid grasshopperChorthippus biguttulus, thoracic auditory interneurons were investigated with respect to their selectivity for temporal parameters of the conspecific song. Special attention was given to the detection of small gaps in the 'syllables' of the song, since behavioural experiments have shown that the presence or absence of gaps is critical for the female's Innate Releasing Mechanism (cf. Fig. 1).The spiking response of one ascending interneuron, the AN4, shows filtering properties which closely resemble the behavioural reactions (cf. Figs. 1, 3 and 5b). The difference in the AN4's reaction to stimuli with gaps and uninterrupted stimuli is maintained over the behaviourally relevant intensity range (Fig. 4). This reaction is reliable enough that the stimulus type could be inferred by higher centres even from single stimulus presentations. Hence, this neuron is likely to participate in the task of gap detection and probably is a part of the neuronal filter network which determines the characteristics of the Innate Releasing Mechanism of this species. However, this interneuron is not species-specific: A homologue exists in other acridids as well and, in Locusta migratoria, has similar response characteristics (Fig. 6). The inferences of this observation for the evolution of an Innate Releasing Mechanism are discussed.

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Section: Interneuron Morphologysupporting

confidence: 54%

Filtering of behaviourally relevant temporal parameters of a grasshopper's song by an auditory interneuron

Ronacher

Stumpner

1988

J. Comp. Physiol.

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“…Appropriate voltages of stimulation produced a single volley arriving at the terminals of afferents or interneurons, as previously described (Pearson et al, 1985;Boyan, 1986).…”

Section: Methodsmentioning

confidence: 99%

“…Wind stimulation of filiform afferent hairs on the cerci can elicit jumping (Hoyle, 1958) and flight (Boyan et al, 1986) in the locust, kicking in the cricket (Huber, 1965), escape running in the cockroach (Camhi, 1980); the cerci are vital for flight stabilization in both the cockroach (Fraser, 1977) and locust (Altman, 1983). Cereal position, in particular, has been shown to determine the directionality of GINS in some species (Rozhkova, 1980;Rozhkova et al, 1984), and in the cockroach, behavioral compensation has been demonstrated in response to experimentally altered cereal position (Comer and Camhi, 1984).…”

Section: Functional Attributes Of the Pad Unitmentioning

confidence: 99%

“…Air currents are also generated during cricket stridulation (Kamper and Dambach, 1985) and cockroach walking (Plummer and Camhi,198 l), and filiform hairs on the cerci detect these air currents (Orida and Josephson, 1978;Plummer and Camhi, 198 1;Kamper, 1984) and mediate phasic effects on the motor output (Dambach et al, 1983). The cerci have been shown to trigger kicking (Huber, 1965) jump behavior (Hoyle, 1958), to initiate flight (Boyan et al, 1986) and to play a role in steering during flight (Fraser, 1977;Altman, 1983).…”

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confidence: 99%

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Presynaptic inhibition of identified wind-sensitive afferents in the cercal system of the locust

Boyan

1988

J. Neurosci.

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The paired cerci located at the tip of the locust abdomen bear a large number of wind-sensitive filiform hairs, each of which sends an axon via the cercal nerve into the terminal ganglion of the CNS. The filiform afferents fire bursts of action potentials when their hairs are displaced by wind or mechanical stimuli. Filiform axon terminals in the CNS are depolarized concomitantly with the discharge of another type of unit (a primary afferent-depolarizing, or PAD, unit) recorded in the cercal nerve. The instantaneous spike frequency of PAD unit discharges matches the evoked depolarization very closely, and during such depolarizations spike amplitudes in the filiform afferent terminals are reduced by up to 55%. Depolarizing current pulses injected into the axonal terminals of an identified filiform afferent evoke spikes that are blocked by the PAD unit, probably via an intercalated interneuron. The PAD unit makes a monosynaptic connection with only one of the 4 giant interneurons (GIN 2) on each side of the terminal ganglion, and indirect connections with 2 others. Depolarizing current pulses injected into the neuropilar segments of GINs evoke fewer spikes when the PAD unit is active, consistent with the PAD unit's mediation of conductance changes in postsynaptic cells. Iontophoretic injection of Lucifer yellow shows the PAD unit to be an afferent with axon terminals overlapping those of filiform afferents and posteriorly directed branches of interneurons such as GIN 2 in the CNS. Passive movements of a cercus, monitored with a position transducer, show that the PAD unit fires discrete bursts during cercal displacement. The PAD unit most probably has its soma and dendrites in tissue spanning the cercal base. By responding to cercal movements sufficient to also activate filiform hairs, and by mediating conductance changes in both the presynaptic terminals of filiform afferents and the postsynaptic membranes of interneurons, the PAD unit desensitizes a pathway to movement-generated afferent input, and ensures that the locust remains sensitive to external wind stimuli.

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Organization of a sensory neuropile in the auditory pathway of two groups of orthoptera

Römer

Marquart

Hardt

1988

J of Comparative Neurology

158

102

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The anterior intermediate sensory neuropile (aISN) is a prominent neuropile in the ventral nerve cord of locusts and bushcrickets. Previous studies have shown that it receives its main sensory input from auditory receptors. In this paper we examine the structural and physiological relationship between tympanal receptor terminations and the dendrites of sound-sensitive interneurones in the homologous neuropile of locusts and bushcrickets. Each individual receptor fibre of the bushcricket terminates in a somewhat different target area of the neuropile. The ordering is with respect to the characteristic frequency of the fibres (tonotopic) in the anterior-posterior and dorsoventral axis. In the locust, representatives of the four tympanal receptor groups branch in different areas of the aISN. Most of the dorsal neuropilar region, and the anterior ventral region, do not receive input from tympanal receptors. The dendrites of identified sound-sensitive interneurones were examined in the context of this afferent projection. Local interneurones as well as intersegmental interneurones in bushcrickets have dendritic branches in the whole aISN or part of it and thus overlap with at least some receptors. By recording intracellularly from their main neurites, short-latency synaptic potentials were found in response to receptor spikes indicating monosynaptic input. The tuning of these neurones could be predicted by their dendritic morphology. In contrast, in the locust only local and bisegmental neurones are monosynaptically connected with tympanal receptors, but not the studied intersegmental neurones. This is consistent with the finding that most or all branches of intersegmental neurones lie in the dorsal area of neuropile where no receptors terminate. Anatomical and physiological evidence is presented for identified local neurones providing the excitatory and inhibitory synaptic input for such intersegmental neurones. The difference in the basic wiring diagram in the homologous neuropile of the two orthopteran groups is discussed with respect to the possible different roles that sound plays in their behaviour.

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Modulation of auditory responsiveness in the locust

Cited by 14 publications

References 39 publications

Filtering of behaviourally relevant temporal parameters of a grasshopper's song by an auditory interneuron

Filtering of behaviourally relevant temporal parameters of a grasshopper's song by an auditory interneuron

Presynaptic inhibition of identified wind-sensitive afferents in the cercal system of the locust

Organization of a sensory neuropile in the auditory pathway of two groups of orthoptera

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