Response of thoracic interneurons to tactile stimulation in the cockroach,Periplaneta americana

Receåfindings indicate that cockroaches escape in response to tactile stimulation as well as they do in response to the classic wind puff stimulus. The thoracic interneurons that receive inputs from ventral giant interneurons also respond to tactile stimulation and therefore, represent a potential site of convergence between wind and tactile stimulation as well as other sensory modalities. In this article, we characterize the tactile response of these interneurons, which are referred to as type-A thoracic interneurons (TI_As). In response to tactile stimulation of the body cuticle, TI_As typically respond with a short latency biphasic depolarization which often passes threshold for action potentials. The biphasic response is not typical of responses to wind stimulation nor of tactile stimulation of the antennae. It is also not seen in tactile responses of thoracic interneurons that are not part of the TI_A group. The responses of individual TI_As to stimulation of various body locations were mapped. The left-right directional properties of TI_As are consistent with their responses to wind puffs from various different directions. Cells that respond equally well to wind from the left and right side also respond equally well to tactile stimuli on the left and right side of the animal's body. In contrast, cells that are biased to wind on one side are also biased to tactile stimulation on the same side. In general, tactile responses directed at body cuticle are phasic rather than tonic, occurring both when the tactile stimulator is depressed and released. The response reflects stimulus strength and follows repeated stimulation quite well. However, the first phase of the biphasic response is more robust during high-frequency stimulation than the second phase. TI_As also respond to antennal stimulation. However, here the response characteristics are complicated by the fact that movement of either antenna evokes descending activity in both left and right thoracic connectives. The data suggest that the TI_As make up a multimodal site of sensory convergence that is capable of generating an oriental escape turn in response to any one of several sensory cues. 1994 John Wiley & Sons, Inc.     

Trehalose turnover and the coexistence of trehalose and active trehalase in cockroach haemolymph

In the cockroaches Periplaneta americana, Periplaneta australasiae, Leucophaea maderae, and Nauphoeta cinerea, undiluted haemolymph, undiluted haemolymph to which 10% solid trehalose was added, and haemolymph diluted 100 or more times with 1% trehalose solution showed approximately equal trehalase activities (3 to 8 mg/ml per hr). No evidence for the presence of a trehalase inhibitor was found.Freshly drawn haemolymph of Periplaneta americana contained 14 to 16 mg trehalose/ml, which on standing was hydrolyzed to glucose at a rate of 4 to 8 mg/ml per hr. In this cockroach, the rate of haemolymph trehalose turnover was only 1.3 mg/ml per hr. This means that in vitro trehalose is hydrolyzed by undiluted haemolymph at several times the rate at which it is replaced in the haemolymph of the intact insect. The mechanism through which trehalose and trehalase can coexist in the haemolymph of the intact cockroach remains therefore unexplained.     

Escape manoeuvres of schooling Clupea harengus

The escape behaviour of schooling herring startled by an artificial sound stimulus was observed by means of high speed video filming. Response latencies showed two distinct peaks, at 30 ms and c . 100 ms. Escape responses belonging to the two latency groups showed different turning rates during the first stage of the response, and showed different escape trajectories. We suggest that long latency escapes may be responses to startled neighbours or simply weak responses to the sound stimulus. In addition, the different contraction rates during the C-bend formation seen in the two latency groups may imply differences in the neuronal commands. The escape responses of herring were directed away from the stimulus more often than towards it (88% of the total). These away responses were more common in long latency responses, suggesting that the latter enable herring to be more accurate in discerning the direction of the threat. Startled fish contracting their body towards the stimulus (performing a towards response) appear to correct their escape course, since their escape trajectory distribution is non-uniformty distributed around 360° and directed away from the stimulus. We hypothesize that when herring are schooling, the ability of each fish to correct its trajectory following turns towards the stimulus is enhanced.     

The adult cervicothoracic musculature of the cockroach, Nauphoeta cinerea (Olivier)

The cervicothoracic musculature of the adult cockroach, Nauphoeta cinerea (Olivier) is described for the first time. The adult thoracic ventral intersegmental muscles are compared with those of the nymph and of the adult cockroach, Periplaneta americana (Linnaeus).     

Side-Dominance of <Emphasis Type="Italic">Periplaneta americana</Emphasis> Persists Through Antenna Amputation

While brain lateralization is widely studied for vertebrates, only a few studies have been performed on insects. In the present research, we investigated the behavior of the common American cockroach, Periplaneta americana, to determine if such lateralization is evident through their decision making process. The roaches were allowed to run through a y-tube and make a decision on which direction to take. Vanilla and ethanol were randomly placed at the ends of the y-tube to entice the roaches to reach the end of the tubes. Tests were repeated by severing one antenna on each roach in different configurations which were expected to alter the decision of the insect. Through a simple statistical analysis we determined that the odors of vanilla and ethanol play an insignificant role in the decision making. We found that injury to the antenna indeed affected their decision, However, similar injury to either antenna showed an innate bias for turning right. Our research supports the hypothesis that Periplaneta americana is right-side dominated in their tactile and odor senses.     

Preliminary studies on the behavioural detection of oestrus in Belgian “Warm-Blood” mares with acoustic and tactile stimuli

The object of this study was to find a reliable, economic, time-saving and easy method to “try” mares for oestrus without the use of a teaser male. The reactions of barren mares, mares with a foal at foot and maiden mares towards the teaser were established and compared to the reactions towards given stimuli. These stimuli were as follows (i) a play-back of acoustic expressions of a courting stallion, (ii) manual tactile manipulation at the neck crest, the flank and the external genitalia and (iii) a combination of these acoustic and tactile stimuli.Mares were tested when in oestrus and in dioestrus. On stimulation, the oestrous signs considered significant were: remaining quiet, lifting the tail, twitching the vulva, spreading the legs, expelling fluid. Signs indicative of dioestrus were: nervousness, kicking and squealing. The preliminary results of observations of 201 Belgian “Warm-Blood” mares showed that oestrus and dioestrus could be detected with virtually as much success by using all three means of stimulation as with the teaser. Few differences were found between barren mares, mares with a foal and maidens. Some oestrous signs (remaining quiet, lifting the tail, spreading the legs) and dioestrous ones (nervousness, kicking) were seen with greater frequency than other signs. Generally speaking, the combination of acoustic and tactile stimulation elicited the most signs. Among the tactile stimulations, pinching the ridge of the neck was ineffective while rubbing the flanks, and especially the external genitalia, was very effective.     

Pedal serotonergic neurons modulate the synaptic input of withdrawal interneurons ofHelix

A group of serotonergic cells, located in the pedal ganglia ofHelix lucorum, modulates synaptic responses of neurons involved in withdrawal behavior. Extracellular or intracellular stimulation of these serotonergic cells leads to facilitation of spike responses to noxious stimuli in the putative command neurons for withdrawal behavior. Noxious tactile stimuli elicit an increase in background spiking frequency in the modulatory neurons and a corresponding increase in stimulus-evoked spike responses in withdrawal interneurons. The serotonergic neurons have processes in the neuropil of the parieto-visceral ganglia complex, consistent with their putative role in modulating the activity of giant parietal interneurons, which send processes to the same neuropil and to the pedal ganglia. The serotonergic cells respond to noxious tactile and chemical stimuli. Although the group as a whole respond to noxious stimuli applied to any part of the body, most cells respond more to ipsilateral than contralateral stimulation, and exhibit differences in receptive areas. Intracellular investigation revealed electrical coupling between serotonergic neurons which could underlie the recruitment of members of the group not responding to a given noxious stimulus.     

Systems of mate selection in a cockroach species with male dominance hierarchies

The system of mate selection in the cockroach, Nauphoeta cinerea, was studied experimentally. The dominant male in a group mates more often than expected if random mating were occurring. The presence of a female usually does not result in changes in the dominance hierarchy, but the frequency of certain behavioural patterns in intermale interactions changes after introduction of the female. Females can discriminate between dominant and non-dominant males on the basis of odour. The experimental approach to this question is somewhat confounded by turning tendencies of the females; data are presented relating female choice to turning tendency.     

The precision of auditory lateralization in the cricket, Gryllus bimaculatus

ABSTRACT. The precision of auditory lateralization was determined behaviourally for the cricket, Gryllus bimaculatus L. A forced-choice Y-maze test was devised in which the cricket, on entering the test arena, could not — in contrast to free phonotactic approaches — change its walking direction until after it had passed through a narrow wire-mesh tunnel. For a sound frequency of 4.7 kHz, matching the species' calling frequency, the minimum audible angle for correct side discrimination was 15°. For stimulus angles smaller than 15° from the longitudinal body axis, the crickets walked randomly to either side; stimulus angles greater than 25° resulted in all crickets turning correctly. These data reveal a sharply tuned lateral sensitivity for the auditory pathway of crickets, with an optimum at the species' calling frequency of 4.7 kHz (when compared with 3.5 and 6.0 kHz). The results for the forced-choice test are compared with the walking pattern during free phonotactic approaches, in order to determine the possible strategy underlying the acoustic orientation behaviour of the cricket.     

Activity and habituation in the brain of the polyclad flatworm Freemania litoricola.

1. A variety of spontaneously active units was measured in the brain of the polyclad flatworm Freemania litoricola. Following application of MgCl2 there was both a decrease in number of active units and a decrease in frequency of firing of those cells which persisted in their activity. 2. Receptors which respond to vibration stimuli evoke potentials in the posterior part of the brain. Repetitive stimulation leads to habituation, the extent of which is dependent on both the number of times stimulated and the strength of the stimulus. Weaker stimuli habituate more rapidly than strong stimuli. Habituated responses can be dishabituated by tactile stimuli and also by stronger intensity stimuli of the same modality. The vibration-evoked potentials appear to occur in at least second-order cells, since vibration responses are abolished by the application of MgCl2. 3. Tactile responses can also be elicited from the posterior portion of the brain when the stimulus is applied to the periphery of the animal. These responses are insensitive to MgCl2. 4. Both vibration and tactile evoked responses are able to evoke further barrages of spike activity. 5. The presence of a dual sensitizing and inhibitory system during habituation is discussed.     

Contingencies in the behaviour of the crab Heterozius rotundifrons

We recorded the responses of individual intertidal crabs, Heterozius rotundifrons, to stimuli presented singly and in combinations in the laboratory. Undisturbed crabs did not respond to the introduction of odour from a crushed conspecific but did respond strongly to food odour. Undisturbed crabs responded equally to food odour alone and a combination of food and odour from a crushed conspecific. When tactile stimulation was applied, as when the crab is grasped by a predator, individual H. rotunidfrons assumed a rigid, appendage-extended posture for several minutes. Tests with predatory fish showed that this catatonic posture is a very effective predator-defence mechanism. The duration of the catatonic state was decreased by the addition of food odour but increased by the addition of alarm odour (crushed conspecific) or the combination of alarm and food odours. Thus, which chemical stimulus was dominant was reversed by tactile input (i.e. dominance was contingent upon context). The effect of alarm odour on food odour responses lasted 4 h. Visual input in the form of a shadow passing over the crabs, either before or after tactile induction of the catatonic state, also increased the duration of that state. However, the duration of the catatonic state following exposure to both cues associated with danger (shadow+alarm odour) was similar to that of the control level. The crabs appeared to switch strategies when three cues associated with danger (tactile grasping, alarm odour and shadows) were detected, either simultaneously or over a 4-h period. The results illustrate the highly contingent nature of the behaviour of these crabs. Copyright 2000 The Association for the Study of Animal Behaviour.     

Characteristics of the infant arousal response

Arousal is considered to be an importantresponse to a life-threatening stimulus. Recently, it has been shownthat the infant arousal response to an elevated inspiredCO₂ level occurs as a sequence ofevents involving presumptive brain stem responses before awakening (A. Lijowska, N. Reed, B. Chiodini, and B. T. Thach. Am.J. Respir. Crit. Care Med. 151: A151, 1995; A. S. Lijowska, N. W. Reed, B. A. Mertins Chiodini, and B. T. Thach.J. Appl. Physiol. 83: 219-228,1997). We wanted to further evaluate the relationship ofsubcortical reflexes to cortical arousal in infants. We used anonrespiratory (tactile) stimulus to elicit arousal in infants duringnon-rapid-eye-movement (NREM) and rapid-eye-movement (REM) sleep. Wefound that a tactile stimulus elicited an arousal sequence thatcommenced with a spinal withdrawal reflex, was followed by brain stemresponses (respiratory and startle responses), and ended in a corticalarousal. The entire pathway or part of it in the order of spinal tocortical responses could be elicited. REM and NREMresponses were similar except for significant differences in thelatencies of spinal and subcortical reflexes. These observations suggest that the infant arousal response to a tactile stimulus involvesa progression of central nervous system activation from the spinal tocortical levels. The different components of the arousal pathway may beimportant for an infant to respond appropriately to stimuli duringsleep without necessarily disturbing sleep.

     

Effect of fipronil on side-specific antennal tactile learning in the honeybee

In the honeybee, the conditioning of the proboscis extension response using tactile antennal stimulations is well suited for studying the side-specificity of learning including the possible bilateral transfer of memory traces in the brain, and the role of inhibitory networks. A tactile stimulus was presented to one antenna in association with a sucrose reward to the proboscis. The other antenna was either not stimulated (A+/0 training), stimulated with a non-reinforced tactile stimulus B (A+/B− training) or stimulated with B reinforced with sucrose to the proboscis (A+/B+ training). Memory tests performed 3 and 24 h after training showed in all situations that a tactile stimulus learnt on one side was only retrieved ipsilaterally, indicating no bilateral transfer of information. In all these groups, we investigated the effect of the phenylpyrazole insecticide fipronil by applying a sublethal dose (0.5 ng/bee) on the thorax 15 min before training. This treatment decreased acquisition success and the subsequent memory performances were lowered but the distribution of responses to the tactile stimuli between sides was not affected. These results underline the role of the inhibitory networks targeted by fipronil on tactile learning and memory processes.     

Dye-coupling between cells of the salivary glands in the cockroach Periplaneta americana

Cockroaches have acinar salivary glands. The acini consist of peripheral cells specialized for electrolyte and water transport and central cells contributing proteinaceous components to the saliva. Salivary duct cells probably modify the primary saliva. The acinar cells in Nauphoeta cinerea had been shown to be electrically coupled and dye-coupled. Since intercellular communication via gap junctions between acinar cells is difficult to reconcile with previous findings that dopamine and serotonin selectively stimulate the secretion of either protein-free or protein-rich saliva in Periplaneta americana, we investigated whether dye-coupling occurs between both acinar cell types and between duct cells. We iontophoretically loaded Lucifer yellow into impaled cells and tested for dye-coupling by confocal laser scanning microscopy. We found that: (1) peripheral and central cells within an acinar lobulus of the gland in P. americana are dye-coupled; and (2) salivary duct cells are dye-coupled.     

The effects of cross-modal manipulations of attention on the detection of vibrotactile stimuli in humans

Although it is well known that attention to a visual or auditory stimulus can enhance its perception, less is known concerning the effects of attention on the perception of natural tactile stimuli. The present study was conducted to examine the magnitude of the effect of cross-modal manipulations of attention in human subjects on the detection of weak, low-frequency vibrotactile stimuli delivered to the glabrous skin of the finger pad of the right index finger via an Optacon. Three suprathreshold vibrotactile arrays (40 Hz), varying in the number of activated pegs and hence the area of skin stimulated, were used. Subjects were trained to detect the occurrence of vibrotactile or visual stimuli and to respond by pressing a foot pedal as quickly as possible thereafter. Two instructional lights were used to cue the subjects as to which stimulus modality they should attend, in three experimental conditions. In the first cue condition, the forthcoming stimulus modality was indicated by the illumination of its associated light. In the second cue condition, both instructional lights were illuminated, and the subjects were asked to divide their attention equally between the two modalities. In the third cue condition, the stimulus modality was falsely indicated by the illumination of the cue not associated with the stimulus to be presented. Reaction times (RTs) were calculated for each trial. For each modality, tactile and visual, the RTs varied significantly with the cue condition, with the mean RT changing in a graded manner across the experimental conditions (being shortest for the correctly cued condition, intermediate for the neutrally cued condition, and longest for the incorrectly cued condition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survival of shelled acanthors of Moniliformis moniliformis (Acanthocephala) under laboratory conditions

Shelled acanthors (= eggs) of two isolates of Moniliformis moniliformis (Acanthocephala) were tested for their capacity to respond to a hatching stimulus in vitro and for their retention of infectivity to a natural intermediate host (Periplaneta americana). The shelled acanthors were stored for more than 120 weeks (Australian isolate) and for 104 weeks (Texan isolate) together with rat faeces in an incubator maintained at 22.2 +/- 0.1 degrees C. In both cases, infectivity to P. americana was shown to have been retained. In vitro tests of the hatching response were carried out on many occasions during this period of faecal storage. Shelled acanthors continued to respond and no differences were detected either between isolates or within an isolate through time.     

Behavioural Components of pheromonal aggregation in Aphis fabae Scopoli

Adult apterous A. fabae were made to walk along straight catwalks between muslin walls behind part of which other, settled aphids were confined. Individuals walking past these concealed aphids were arrested there and started to probe or turn, showing a positive taxis, inverse orthokinesis, and probably also inverse klinokinesis, all presumably in response to aphid odour. Walking aphids also responded to the visual stimulus of a black vertical stripe by turning towards it and this response was stronger than the olfactory orientation response and seemed to inhibit it. On the other hand, aphid odour enhanced the visual orientation response to the stripe.     

Visual control of turning responses to tactile stimuli in the crayfishProcambarus clarkii

Summary Specimens of the crayfishProcambarus clarkii turn to face in the direction of a brief tactile stimulus delivered to a walking leg. The control system that guides this directed behavior was investigated under closed-loop and open-loop conditions. The accuracy of turns exhibited in these experiments was compared to baseline accuracy established by animals restrained from forward and backward walking but allowed to rotate in the yaw plane. Procambarus clarkii individuals deprived of visual feedback tended to undershoot the target angle. Response accuracy increased when a uniform field of stripes moved across the visual field in accordance with the turning movements of the animal. Response accuracy did not match the accuracy observed under baseline conditions, however, unless the responding animal encountered a novel visual image, such as the silhouette of a crayfish, in the moving visual field.Visual feedback thus influences the accuracy of turning in crayfish in two important ways. Movement of stripes across the visual field of a crayfish feeds back positively and promotes rapid turning during the initial phase of a response. This effect obtains regardless of the direction or rate of movement of the stripes in the visual field. The appearance of a novel image in the visual field feeds back negatively to inhibit at least partially further turning. Feedback from the visual system appears to fine tune basic turning movements initiated by a tactile stimulus and crudely directed according to that input. Turning behavior in the crayfish resembles in this respect compensatory eye movements in the lobster and escape responses in a number of arthropods.Neural mechanisms that may explain the experimental results are discussed with particular emphasis on the possibility of interaction between voluntary turning responses and optomotor reactions.     

Why do male Callosobruchus maculatus harm their mates?

Males of the bruchid beetle Callosobruchus maculatus have spineson their intromittent organs that puncture the female reproductivetract during mating. Females kick their mates during copulation.If females are prevented from kicking the males, copulationslast longer and the injuries females sustain are more severe.We tested whether or not these injuries represent real fitnesscosts that can be mitigated by kicking and also what males gainby inflicting them. Our results show that females do indeedsuffer lowered lifetime fecundity if they are prevented fromkicking. However, we could find no evidence that males gainbenefits through harming their mates. It has been suggestedthat the way females respond to the harm may benefit the malecausing it. Injured females may be less willing to remate toavoid sustaining further injuries, or they may respond by increasingtheir rate of oviposition if they perceive the injuries as athreat to their survival. In our study, however, females thatwere prevented from kicking did not respond by delaying rematingor increasing their rate of oviposition. Furthermore, preventingfemales from kicking during their second copulation did notmake their second mates more successful in sperm competition.This suggests that the spines have evolved for other reasonsthan harming the females, such as serving as an anchor duringcopulation, and that the harm they cause is a side effect ofa male adaptation and is not itself adaptive for either sex.     

Arthropod touch reception: stimulus transformation and finite element model of spider tactile hairs

Striving towards an in depth understanding of stimulus transformation in arthropod tactile hairs, we studied the mechanical events associated with tactile stimulation. A finite element model was developed taking a tarsal tactile hair of the spider Cupiennius salei as an example. Considering hair diameter, wall thickness, and curvature, the hair is subdivided into six regions each with its specific mechanical properties. When the hair is touched from above with a flat surface oriented parallel to the tarsus the point of stimulus contact moves towards the hair base with increasing load and hair deflection. Thereby the effective lever arm is reduced protecting the hair against breaking near its base. At the same time the mechanical working range of the hair increases implying higher mechanical sensitivity for small deflections (about 5x10(-5) N/degrees) than for large deflections (about 1x10(-4) N/degrees). The major stresses within the hair shaft are axial stresses due to bending. The position of stress maxima moves along the shaft with the movement of the stimulus contact point. Remarkably, the amplitude of this maximum (about 1x10(5) N/m2) hardly changes with increasing loading force due to the way the hair shaft is deflected by the stimulus.