An antennal-derived mechanosensory pathway in the cockroach: descending interneurons as a substrate for evasive behavior

1990 ◽  
Vol 535 (2) ◽  
pp. 347-352 ◽  
Author(s):  
John A. Burdohan ◽  
Christopher M. Comer
Keyword(s):  
Descending Interneurons

Three descending interneurons reporting deviation from course in the locust

1986 ◽  
Vol 158 (6) ◽  
pp. 775-794 ◽  
Author(s):  
C. H. F. Rowell ◽  
H. Reichert
Keyword(s):  
Descending Interneurons

scholarly journals A Novel Neuronal Pathway for Visually Guided Escape in Drosophila melanogaster

2009 ◽  
Vol 102 (2) ◽  
pp. 875-885 ◽  
Author(s):  
Haleh Fotowat ◽  
Amir Fayyazuddin ◽  
Hugo J. Bellen ◽  
Fabrizio Gabbiani
Keyword(s):  
Drosophila Melanogaster ◽  
Activity Pattern ◽  
Escape Response ◽  
Angular Size ◽  
The Novel ◽  
Visually Guided ◽  
Motor Sequence ◽  
Motor Programs ◽  
Sensory Activity ◽  
Descending Interneurons

Drosophila melanogaster exhibits a robust escape response to objects approaching on a collision course. Although a pair of large command interneurons called the giant fibers (GFs) have been postulated to trigger such behaviors, their role has not been directly demonstrated. Here, we show that escape from visual stimuli like those generated by approaching predators does not rely on the activation of the GFs and consists of a more complex and less stereotyped motor sequence than that evoked by the GFs. Instead, the timing of escape is tightly correlated with the activity of previously undescribed descending interneurons that signal a threshold angular size of the approaching object. The activity pattern of these interneurons shares features with those of visual escape circuits of several species, including pigeons, frogs, and locusts, and may therefore have evolved under similar constraints. These results show that visually evoked escapes in Drosophila can rely on at least two descending neuronal pathways: the GFs and the novel pathway we characterize electrophysiologically. These pathways exhibit very different patterns of sensory activity and are associated with two distinct motor programs.

scholarly journals Physiological characterisation of antennal mechanosensory descending interneurons in an insect (Gryllus bimaculatus, Gryllus campestris) brain

2001 ◽  
Vol 204 (13) ◽  
pp. 2265-2275 ◽  
Author(s):  
Michael Gebhardt ◽  
Hans-Willi Honegger
Keyword(s):  
Electrical Stimulation ◽  
Experimental Evidence ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Sensory Nerves ◽  
Gryllus Bimaculatus ◽  
Central Origin ◽  
Gryllus Campestris ◽  
Descending Interneurons ◽  
Stimulation Of

SUMMARY We investigated five different descending brain interneurons with dendritic arborizations in the deutocerebrum in the crickets Gryllus bimaculatus and G. campestris. These interneurones convey specific antennal mechanosensory information to the ventral nerve cord and all responded to forced antennal movements. These interneurones coded for velocity and showed preferences for distinct sectors of the total range of antennal movements. Their axons descended into the posterior connective either ipsilateral or contalateral to the cell body. Electrical stimulation of sensory nerves indicated that the interneurons received input from different afferents of the two antennal base segments. One interneuron had a particularly large axon with a conduction velocity of 4.4ms−1. This was the only one of the five interneurons that also received visual input. Its activity was reduced during voluntary antennal movements. The reduction in activity occurred even after de-efferentation of the antenna, indicating that it had a central origin. Although we do not have experimental evidence for behavioural roles for the descending antennal mechanosensory interneurons, the properties described here suggest an involvement in the perception of objects in the path of the cricket.

Excitation of motoneurons by the Mauthner axon in goldfish: complexities in a "simple" reticulospinal pathway

1992 ◽  
Vol 67 (6) ◽  
pp. 1574-1586 ◽  
Author(s):  
J. R. Fetcho
Keyword(s):  
Escape Behavior ◽  
Mean Amplitude ◽  
Short Latency ◽  
The Body ◽  
Intracellular Recordings ◽  
M Cell ◽  
Mauthner Cell ◽  
Monosynaptic Connection ◽  
Direct Excitation ◽  
Descending Interneurons

1. The Mauthner cell in fish and amphibians initiates an escape behavior that has served as a model system for studies of the reticulospinal control of movement. This behavior consists of a very rapid bend of the body and tail that is thought to arise from the monosynaptic excitation of large primary motoneurons by the Mauthner cell. Recent work suggests that the excitation of primary motoneurons might be more complex than a solely monosynaptic connection. To examine this possibility, I used intracellular recording and staining to study the excitation of primary motoneurons by the M cell. 2. Simultaneous intracellular recordings from the M axon and ipsilateral primary motoneurons show that firing the M cell leads to complex postsynaptic potentials (PSPs) in the motoneurons. These PSPs usually have three components: an early, small, slow depolarization (component 1), a later, large, fast depolarization (component 2), and an even later, large, long-lasting depolarization (component 3). The first component has a latency of 0.52 +/- 0.15 (SD) ms, (n = 27) and most probably is a monosynaptic input from the M cell. This study focused on the two subsequent, less-understood parts of the PSP. Motoneurons typically fire off the second part of the PSP. This is usually (27 of 33 cells) the largest component, and it has a mean amplitude of 6.24 +/- 3.33 (SD) mV (n = 33) and a half-decay time of 0.44 +/- 0.18 (SD) ms (n = 27). The mean amplitude of the third component is 3.20 +/- 1.7 (SD) mV (n = 35), and its half-decay is 6.73 +/- 2.66 (SD) ms (n = 35). The latency of the second component averages 0.66 +/- 0.21 (SD) ms (n = 32), indicating that there are few synapses in the pathway mediating it. 3. One candidate pathway for the second component of the PSP involves a class of descending interneurons (DIs) that are monosynaptically, chemically excited by the M cell and appear in light microscopy to contact motoneurons. Simultaneous intracellular recordings from the M axon, a DI, and a primary motoneuron show that the interneurons are electrotonically coupled to motoneurons and produce the fast, second component of the PSP. Direct excitation of an interneuron leads to a very short-latency (less than 0.2 ms), fast PSP in a motoneuron similar to the second component of the PSP produced by the M axon. The short latency and fatigue resistance of this connection indicate it is electrotonic, and this is supported by evidence for DC coupling between the two cells.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals The modulation of two motor behaviors by persistent sodium currents in Xenopus laevis tadpoles

2017 ◽  
Vol 118 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Erik Svensson ◽  
Hugo Jeffreys ◽  
Wen-Chang Li
Keyword(s):  
Action Potentials ◽  
Sodium Current ◽  
Repetitive Firing ◽  
Sodium Currents ◽  
Spinal Neurons ◽  
Motor Behaviors ◽  
Low Concentrations ◽  
Descending Interneurons ◽  
Lateral Sclerosis

Persistent sodium currents ( INaP) are common in neuronal circuitries and have been implicated in several diseases, such as amyotrophic lateral sclerosis (ALS) and epilepsy. However, the role of INaP in the regulation of specific behaviors is still poorly understood. In this study we have characterized INaP and investigated its role in the swimming and struggling behavior of Xenopus tadpoles. INaP was identified in three groups of neurons, namely, sensory Rohon-Beard neurons (RB neurons), descending interneurons (dINs), and non-dINs (neurons rhythmically active in swimming). All groups of neurons expressed INaP, but the currents differed in decay time constants, amplitudes, and the membrane potential at which INaP peaked. Low concentrations (1 µM) of the INaP blocker riluzole blocked INaP ~30% and decreased the excitability of the three neuron groups without affecting spike amplitudes or cellular input resistances. Riluzole reduced the number of rebound spikes in dINs and depressed repetitive firing in RB neurons and non-dINs. At the behavior level, riluzole at 1 µM shortened fictive swimming episodes. It also reduced the number of action potentials neurons fired on each struggling cycle. The results show that INaP may play important modulatory roles in motor behaviors. NEW & NOTEWORTHY We have characterized persistent sodium currents in three groups of spinal neurons and their role in shaping spiking activity in the Xenopus tadpole. We then attempted to evaluate the role of persistent sodium currents in regulating tadpole swimming and struggling motor outputs by using low concentrations of the persistent sodium current antagonist riluzole.

scholarly journals Excitatory motor neurons are local oscillators for backward locomotion

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Shangbang Gao ◽  
Sihui Asuka Guan ◽  
Anthony D Fouad ◽  
Jun Meng ◽  
Taizo Kawano ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Oscillatory Activity ◽  
Intrinsic Activity ◽  
Chemical Synapse ◽  
C Elegans ◽  
Cell Ablation ◽  
State Dependent ◽  
Evolutionarily Conserved ◽  
Dependent Inhibition ◽  
Descending Interneurons

Cell- or network-driven oscillators underlie motor rhythmicity. The identity of C. elegans oscillators remains unknown. Through cell ablation, electrophysiology, and calcium imaging, we show: (1) forward and backward locomotion is driven by different oscillators; (2) the cholinergic and excitatory A-class motor neurons exhibit intrinsic and oscillatory activity that is sufficient to drive backward locomotion in the absence of premotor interneurons; (3) the UNC-2 P/Q/N high-voltage-activated calcium current underlies A motor neuron’s oscillation; (4) descending premotor interneurons AVA, via an evolutionarily conserved, mixed gap junction and chemical synapse configuration, exert state-dependent inhibition and potentiation of A motor neuron’s intrinsic activity to regulate backward locomotion. Thus, motor neurons themselves derive rhythms, which are dually regulated by the descending interneurons to control the reversal motor state. These and previous findings exemplify compression: essential circuit properties are conserved but executed by fewer numbers and layers of neurons in a small locomotor network.

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