The Anatomy of a Locust Visual Interneurone; the Descending Contralateral Movement Detector

1974 ◽  
Vol 60 (1) ◽  
pp. 1-12
Author(s):  
M. O'SHEA ◽  
C. H. F. ROWELL ◽  
J. L. D. WILLIAMS
Keyword(s):  
Visual Field ◽  
Optic Lobe ◽  
Morphological Description ◽  
Movement Detector ◽  
Branching Pattern ◽  
Suboesophageal Ganglion ◽  
Metathoracic Ganglion ◽  
Prothoracic Ganglion ◽  
Contralateral Movement ◽  
The Brain

1. The DCMD neurone is physiologically well-known and runs from the brain to the metathoracic ganglion. It responds to novel movement of small contrasting objects in the visual field and synapses on metathoracic motoneurones which mediate the jump of the locust. Its anatomy, here reported, has been visualized by intracellular cobalt staining. 2. The soma is 50 µm in diameter and lies on the upper posterior face of the protocerebrum, lateral to the midline. A neurite runs to a thickened integrating segment 20 µm. in diameter, which bears numerous dendrites; none of these extends to the optic lobe. An axon leaves the integrating segment, crosses the brain, thickens to about 17µm and descends the contralateral nerve cord. 3. The descending axon terminates in the metathoracic ganglion, where it has three major branches both ipsi- and contralateral. Its branching in the mesothoracic ganglion is similar, but extends only ipsilaterally; in the prothoracic ganglion there is reduced branching, and in the suboesophageal ganglion none at all. 4. The branching pattern in the metathorax is compatible with, and entirely explicable by, the known synaptic connexions with motoneurones. 5. The morphological description of the cell has made possible intracellular recording from axon, integrating segment and soma.

Central Mechanism of Hearing in Insects

1961 ◽  
Vol 38 (3) ◽  
pp. 545-558 ◽  
Author(s):  
NOBUO SUGA ◽  
YASUJI KATSUKI
Keyword(s):  
Sound Source ◽  
Threshold Curve ◽  
Inhibitory Interaction ◽  
Response Range ◽  
Metathoracic Ganglion ◽  
Hair Sensilla ◽  
Prothoracic Ganglion ◽  
Tympanic Organ ◽  
Large Fibre ◽  
The Brain

1. The impulses from the tympanic organ are transmitted at the prothoracic ganglion to a central neuron, the auditory T large fibre, which lies in the cord between the brain and the metathoracic ganglion. The impulses in the T large fibre are conducted rostrally and caudally with the same discharge pattern. Information is sent up to the brain, and down to the metathoracic ganglion, after a delay of about 12 msec. 2. The impulses from the cercal hair sensilla are transmitted to two similar auditory C large fibres which lie in the cord between the metathoracic and last (6th) abdominal ganglia and are then sent up to the mesothoracic ganglia by other auditory large fibres. 3. Central inhibitory interaction between the impulses from the tympanic nerves of the two sides are shown by a marked increase of impulses in the T large fibre following section of one of the tympanic nerves. No inhibitory interaction is found between the impulses from the two cercal nerves. 4. The auditory T large fibre receives not only the excitatory effect from the ipsilateral tympanic nerve at the prothoracic ganglion, but also the inhibitory and weak excitatory effects from the contralateral one. 5. The response range of the T large fibre is narrower than the threshold curve of the tympanic nerve and corresponds with one type of response range in the tympanic neurons. The response ranges of the C large fibres correspond closely with the threshold curve of the cercal nerve. 6. A large difference in threshold between the two T large fibres is found in the response to sound incident from the side. The number of impulses in the T large fibre nearer to the sound source is greater than in that farther from the source. 7. The difference in the number of impulses between the two T large fibres is most marked in the response to sound of the frequency which is dominant in stridulation. This difference is due to the mutual inhibitory interaction of neurons which modifies the number of impulses without changing the threshold of the tympanic large fibre. 8. It is suggested that the central inhibitory interaction increases the information about a sound source and plays an important role in the mechanism of the directional sense. 9. The stridulation of the group activates the tympanic nerve and evokes synchronized discharge in the T large fibre, but scarcely at all in the primary C large fibre. The tympanic organ and its neural network seem well adapted to reception of stridulation. 10. It is concluded that though neither of the two sound receptive organs--the tympanic organ and the cercal hair sensilla--can perform frequency analysis, the insect may be able to do so by making use of both organs, since they have different frequency ranges and are served by different auditory large-fibre tracts.

A looming-sensitive pathway responds to changes in the trajectory of object motion

2012 ◽  
Vol 108 (4) ◽  
pp. 1052-1068 ◽  
Author(s):  
Glyn A. McMillan ◽  
John R. Gray
Keyword(s):  
Visual Field ◽  
Firing Rate ◽  
Visual Motion ◽  
Compound Eye ◽  
Angular Acceleration ◽  
Leading Edge ◽  
Object Motion ◽  
Near Miss ◽  
Movement Detector ◽  
Contralateral Movement

Two identified locust neurons, the lobula giant movement detector (LGMD) and its postsynaptic partner, the descending contralateral movement detector (DCMD), constitute one motion-sensitive pathway in the visual system that responds preferentially to objects that approach on a direct collision course and are implicated in collision-avoidance behavior. Previously described responses to the approach of paired objects and approaches at different time intervals (Guest BB, Gray JR. J Neurophysiol 95: 1428–1441, 2006) suggest that this pathway may also be affected by more complicated movements in the locust's visual environment. To test this possibility we presented stationary locusts with disks traveling along combinations of colliding (looming), noncolliding (translatory), and near-miss trajectories. Distinctly different responses to different trajectories and trajectory changes demonstrate that DCMD responds to complex aspects of local visual motion. DCMD peak firing rates associated with the time of collision remained relatively invariant after a trajectory change from translation to looming. Translatory motion initiated in the frontal visual field generated a larger peak firing rate relative to object motion initiated in the posterior visual field, and the peak varied with simulated distance from the eye. Transition from translation to looming produced a transient decrease in the firing rate, whereas transition away from looming produced a transient increase. The change in firing rate at the time of transition was strongly correlated with unique expansion parameters described by the instantaneous angular acceleration of the leading edge and subtense angle of the disk. However, response time remained invariant. While these results may reflect low spatial resolution of the compound eye, they also suggest that this motion-sensitive pathway may be capable of monitoring dynamic expansion properties of objects that change the trajectory of motion.

scholarly journals Characterization of a reduced-eye mutant of the grasshopper, Melanoplus sanguinipes

Development ◽  
1984 ◽  
Vol 83 (1) ◽  
pp. 189-211
Author(s):  
D. J. Emery ◽  
K. A. Bell ◽  
W. Chapco ◽  
J. D. Steeves
Keyword(s):  
Compound Eye ◽  
Optic Lobe ◽  
Compound Eyes ◽  
Movement Detector ◽  
Melanoplus Sanguinipes ◽  
Optic Chiasma ◽  
Morphological Alterations ◽  
Tactile Stimuli ◽  
Normal Manner ◽  
Contralateral Movement

A reduced-eye (re) mutant grasshopper of Melanoplus sanguinipes has been characterized by small flat compound eyes lacking facets, no lateral ocelli and only a remnant of the median ocellus. The re grasshoppers walk, jump, fly and feed in a normal manner, but do not respond to visual and auditory stimuli, suggesting they may be blind and deaf. Extracellular recordings from the ventral nerve cord of re mutants verified the lack of neural activity in response to visual and auditory inputs, yet the mutants detected mechanical and tactile stimuli. Electroretinograms implied that a visual deficit may be within the photoreceptors of the compound eye. Histological examination of the compound eyes and ocelli indicated that the cells of the mutant compound eye incompletely differentiate. The optic lamina underlying the retina is missing, as is the outer optic chiasma. The medulla and lobula of the mutant optic lobe are present, however, the neuropil of the medulla lacks the characteristic axonal projection patterns of wild-type grasshoppers. The re grasshopper also lacks all ocellar nerves. Ocellar nerves are normally formed from processes of second order ocellar neurons (SONs), suggesting that if the mutant SONs are present within the protocerebrum, their morphology is drastically altered. Comparison of embryos and juvenile nymphs supports the suggestion that the alterations in the re visual system are the result of abnormal differentiation during development. Even though there is clear evidence of morphological alterations in second and third order optic lobe interneurons, one higher order visual interneuron of the midbrain, the descending contralateral movement detector (DCMD), has the same morphology as the DCMD in a wildtype brain. In this instance, the complete deprivation of the primary sensory input does not appear to alter cellular development.

Identified octopaminergic neurons provide an arousal mechanism in the locust brain

1995 ◽  
Vol 74 (6) ◽  
pp. 2739-2743 ◽  
Author(s):  
J. P. Bacon ◽  
K. S. Thompson ◽  
M. Stern
Keyword(s):  
Action Potentials ◽  
Tactile Stimulation ◽  
Neural Circuit ◽  
Optic Lobe ◽  
Repetitive Stimulation ◽  
Movement Detector ◽  
Optic Lobes ◽  
Tactile Stimuli ◽  
Arousal Mechanism ◽  
Contralateral Movement

1. Habituation is the declining responsiveness of a neural circuit (or behavior) to repetitive stimulation. Dishabituation (or arousal) can be brought about by the sudden presentation of an additional, novel stimulus. A clear example of arousal in the locust is provided by the visual system: the habituated response of the descending contralateral movement detector (DCMD) interneuron to repetitive visual stimuli can be dishabituated by a variety of other visual and tactile stimuli. 2. Application of octopamine to the locust brain and optic lobes dishabituates the DCMD in a manner similar to the effect of visual and tactile stimulation. 3. The locust CNS contains two pairs of octopamine-immunoreactive cells, the protocerebral medulla 4 (PM4) neurons, that could potentially mediate this dishabituation effect; PM4 neurons arborize in the optic lobe, they contain octopamine, and they respond to the same visual and tactile stimuli that dishabituate the DCMD. 4. To investigate whether PM4 activity dishabituates the DCMD, we recorded intracellularly from one of the PM4 neurons while recording extracellularly from the DCMD. When the PM4 neuron is injected with hyperpolarizing current to render it completely inactive, the DCMD exhibits its characteristic habituation to a moving visual stimulus. However, depolarizing the PM4 neuron, to produce action potentials at approximately 20 Hz, significantly increases the number of DCMD action potentials per stimulus. 5. The PM4 neurons may therefore play an important role in dishabituating the DCMD to novel stimuli. This effect is presumably mediated by PM4 neurons releasing endogenous octopamine within the optic lobe.

Neuronal basis of a sensory analyser, the acridid movement detector system. III. Control of response amplitude by tonic lateral inhibition

1976 ◽  
Vol 65 (3) ◽  
pp. 617-625
Author(s):  
C. H. Fraser Rowell ◽  
M. O'Shea
Keyword(s):  
Visual Field ◽  
Lateral Inhibition ◽  
Optic Lobe ◽  
Inhibitory Effect ◽  
Test Area ◽  
Detector System ◽  
Movement Detector ◽  
Field Change ◽  
Surrounding Area ◽  
Small Areas

1. The Lobular Giant Movement Detector neurone (LGMD) of Schistocerca responds with spikes when small areas of the visual field change in luminance. Previous work has shown that changes of +/− 1 log 10 unit are enough to produce maximal ON and OFF responses. 2. Using a 5 degree test area, it is shown that the number of spikes generated by such a stimulus depends on the luminance of the surrounding area. When the surround is dark, the response is maximal; when it is brightly lit, the response is minimal. Intermediate intensities produce intermediate values of response. A X 2 change in response is produced by about 3 log 10 units change in surround intensity. 3. A bright annulus, with diameters of 10-5 degrees and 25-8 degrees, inhibits both ON and OFF responses when concentric with the 5 degree test area, but not when it is 30 degrees eccentric to the test area. The inhibitory effect shows no decrease after 4 min. 4. These results are interpreted to indicate a tonic lateral inhibitory network, sited peripherally in the optic lobe prior to the divergence of the separate ON and OFF channels found in the projection from the medulla to the LGMD. It is probably identical with that described for the lamina by previous workers.

Morphology of neurons in locust brain and suboesphageal ganglion involved in initiation and maintenance of walking

1983 ◽  
Vol 219 (1215) ◽  
pp. 175-192 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Cobalt Nitrate ◽  
Suboesophageal Ganglion ◽  
Brain Neurons ◽  
Glass Microelectrode ◽  
Prothoracic Ganglion ◽  
The Brain ◽  
Lateral Protocerebrum

Electrical stimulation through a glass microelectrode positioned in the neck or circumoesophageal (co.) connective can evoke walking in a tethered locust. Cobalt nitrate was injected through the stimulating electrode to stain the involved neurons extracellularly. The cobalt travelled from injections at stimulating positions in the co. connective to stain fibres in the brain and suboesophageal ganglion (so. g.). Injections in the neck connectives stained fibres in the so. g. and prothoracic ganglion. In the brain, neurons stained from co. connective positions where walking forwards, walking backwards or turning had been evoked branched predominantly in the dorsal deutocerebrum. In stains where sideways walking had been evoked there was more branching in the lateral protocerebrum than in the deutocerebrum. Primary sensory fibres, particularly those in the dorsal tegumentary nerve, were often stained. These also branch in the dorsal deutocerebrum before descending. The so. g. contributes its own plurisegmental fibres, which may be ascending or both. Many fibres branched bilaterally.

A guide to the neuroanatomy of locust suboesophageal and thoracic ganglia

1982 ◽  
Vol 297 (1085) ◽  
pp. 91-123 ◽  
Keyword(s):  
Peripheral Nerve ◽  
Nerve Fibre ◽  
Schistocerca Gregaria ◽  
Locusta Migratoria ◽  
Suboesophageal Ganglion ◽  
Thoracic Ganglia ◽  
Locusta Migratoria Migratorioides ◽  
Basic Framework ◽  
Metathoracic Ganglion ◽  
The Brain

The organization of the thoracic and suboesophageal ganglia in the locust is presented to provide a framework into which details of individual neurons can be inserted as information becomes available. Three species were examined, Chortoicetes terminifera (Walker), Schistocerca gregaria (Forskål) and Locusta migratoria migratorioides (Reiche and Fairmaire). The basic plan of the ganglia is similar in all three species. Series of selected sections in transverse, horizontal and sagittal planes are illustrated to show the arrangement of the main nerve fibre tracts and areas of neuropil, and these are described briefly. A guide is given to prominent features that assist in the interpretation of sections in each plane. In the simpler mesothoracic and prothoracic ganglia nine longitudinal tracts are present in each half of the neuromere, and six dorsal and four ventral transverse tracts (commissures) link the two halves. Four vertical or oblique tracts are conspicuous, the T-tract, ring tract, C-tract and I-tract. Major roots of each peripheral nerve useful as landmarks are numbered from anterior to posterior. Two regions of fine fibrous neuropil are prominent, the ventral association centre and an area associated with the ring tract, a little above it. In the metathoracic ganglion three abdominal neuromeres are fused posteriorly to the true metathoracic neuromere. All four neuromeres show modification of the basic framework chiefly in the arrangement of the ventral commissures and the degree of development of the ventral association centre. In the suboesophageal ganglion three neuromeres, mandibular, maxillary and labial, are fused together from anterior to posterior. They show increasing modification of the basic plan anteriorly. Additional anterior longitudinal tracts are present, which connect with the brain, the dorsal commissures are much reduced and compressed, particularly in the mandibular neuromere, and the ventral commissures of all three neuromeres differ considerably from those of the thoracic ganglia.

Spatiotemporal stimulus properties modulate responses to trajectory changes in a locust looming-sensitive pathway

2014 ◽  
Vol 111 (9) ◽  
pp. 1736-1745 ◽  
Author(s):  
Paul C. Dick ◽  
John R. Gray
Keyword(s):  
Visual Field ◽  
Firing Rate ◽  
Translational Motion ◽  
Object Motion ◽  
Movement Detector ◽  
Natural Conditions ◽  
Avoidance Behaviors ◽  
Contralateral Movement ◽  
Direct Collision ◽  
Low Amplitude

The lobula giant movement detector (LGMD) and descending contralateral movement detector (DCMD) constitute one motion-sensitive pathway in the locust visual system that is implicated in collision-avoidance behaviors. While this pathway is thought to respond preferentially to objects approaching on a direct collision course, emerging studies suggest the firing rate is able to monitor more complicated movements that would occur under natural conditions. While previous studies have compared the response of the DCMD to objects on collision courses that travel at different speeds, velocity has not been manipulated for other simple or compound trajectories. Here we test the possibility that the LGMD/DCMD pathway is capable of responding uniquely to complex aspects of object motion, including translation and trajectory changes at different velocities. We found that the response of the DCMD to translational motion initiated in the caudal visual field was a low-amplitude peak in firing rate that occurred before the object crossed 90° azimuth that was invariant to different object velocities. Direct looms at different velocities resulted in peak firing rates that occurred later in time and with greater amplitude for higher velocities. In response to transitions from translational motion to a collision course, the firing rate change depended on both the location within the visual field and the velocity. These results suggest that this pathway is capable of conveying information about multiple properties of a moving object's trajectory.

A neuroanatomical map of the suboesophageal and prothoracic ganglia of the honey bee ( Apis mellifera )

1988 ◽  
Vol 235 (1279) ◽  
pp. 179-202 ◽  
Keyword(s):  
Honey Bee ◽  
Dorsal Part ◽  
Serial Sections ◽  
Suboesophageal Ganglion ◽  
Structural Context ◽  
Basic Organization ◽  
Prothoracic Ganglion ◽  
Staining Methods ◽  
The Brain ◽  
Anterior Posterior

The basic organization of the prothoracic and suboesophageal ganglia of the honey bee is described from transverse, horizontal, and sagittal serial sections by using a variety of staining methods. Drawings of sections demonstrate neuropils, tracts, commissures, clusters of somata and other conspicuous landmarks. These provide the elements of a map of the ganglion in which specific neurons can be related to their structural context. The prothoracic ganglion contains nine longitudinal tracts in each hemiganglion. Six main dorsal and four ventral commissures link the two halves of the ganglion together. Other conspicuous structures are the ventral association centre and a T-tract: a ring tract is not strongly developed. The suboesophageal ganglion (SOG) is a fusion of the mandibular, maxillary, and labial neuromeres, the latter clearly showing the same basic organization as that found in the prothoracic ganglion. The more anterior mandibular and maxillary neuromeres successively decrease in volume compared with the posterior labial neuromere. Whereas the ventral parts of the neuromeres are demarcated from each other by prominent midline tracts, the dorsal part of each neuromere is confluent with the next. This may be, in part, due to the tilt of about 90° in the anterior-posterior axis (neuraxis) between the suboesophageal ganglion and the brain. Presumably, in morphogenesis this results in a compression of the dorsal parts of the suboesophageal ganglion. Eight longitudinal tracts run through each half of the ganglion. The number of main dorsal commissures declines from six in the labial to five in the maxillary and three in the mandibular neuromere. There are five ventral commissures in the maxillary, and four in both the mandibular and labial neuromeres. The organization of the suboesophageal and pro­thoracic ganglia in the honey bee is compared with those found in the cockroach, locust and cricket. The data support the hypothesis that insect ganglia have a common morphological building plan.

Responses of a Looming-Sensitive Neuron to Compound and Paired Object Approaches

2006 ◽  
Vol 95 (3) ◽  
pp. 1428-1441 ◽  
Author(s):  
Bruce B. Guest ◽  
John R. Gray
Keyword(s):  
Visual Field ◽  
Movement Detector ◽  
Azimuthal Position ◽  
Target Neuron ◽  
Object Edge ◽  
Contralateral Movement ◽  
Predicted Values ◽  
Firing Properties ◽  
Nonlinear Integration ◽  
Individual Objects

The lobula giant movement detector (LGMD) and its target neuron, the descending contralateral movement detector (DCMD), constitute a motion-sensitive pathway in the locust visual system that responds preferentially to objects approaching on a collision course. LGMD receptive field properties, anisotropic distribution of local retinotopic inputs across the visual field, and localized habituation to repeated stimuli suggest that this pathway should be sensitive to approaches of individual objects within a complex visual scene. We presented locusts with compound looming objects while recording from the DCMD to test the effects of nonuniform edge expansion on looming responses. We also presented paired objects approaching from different regions of the visual field at nonoverlapping, closely timed and simultaneous approach intervals to study DCMD responses to multiple looming stimuli. We found that looming compound objects evoked characteristic responses in the DCMD and that the time of peak firing was consistent with predicted values based on a weighted ratio of the half size of each distinct object edge and the absolute approach velocity. We also found that the azimuthal position and interval of paired approaches affected DCMD firing properties and that DCMDs responded to individual objects approaching within 106 ms of each other. Moreover, comparisons between individual and paired approaches revealed that overlapping approaches are processed in a strongly sublinear manner. These findings are consistent with biophysical mechanisms that produce nonlinear integration of excitatory and feed-forward inhibitory inputs onto the LGMD that have been shown to underlie responses to looming stimuli.

Sign in / Sign up

Export Citation Format

Share Document