Fixed Action Patterns Research Articles

Hiccup reflex is mediated by pharyngeal branch of glossopharyngeal nerve in cats

Hiccup reflex is a coordinated motor activity that causes a brief strong inspiratory movement accompanied by glottic adduction. Our previous study has demonstrated that mechanical stimulation of the dorsal epipharynx elicits hiccup-like response. To identify the afferent pathway of the hiccup-like response, the pharyngeal branch of the glossopharyngeal nerve (PB-GPN) which distributed to the dorsal epipharyngeal area was electrically stimulated in anesthetized, spontaneously breathing cats. To access the epipharynx and to directly observe a glottic movement, we made a submental opening at the region rostral to the epiglottis. An activity from the lateral cricoarytenoid (LCA) muscle of the larynx was recorded as an index of glottic adduction, and intrapleural pressure (Ppl) as an index of an inspiratory movement. Electrical stimulation of PB-GPN evoked a fixed motor pattern of hiccup-like response representing a spiky strong negative change in Ppl accompanied by an initial brief burst of LCA electromyogram (EMG). LCA excitation occurred prior to the spiky inspiratory movement. An initial and transient glottic adduction during the response was confirmed by direct observation. Electrical stimulation of the main trunk of the glossopharyngeal nerve evoked expiratory reflex, but not inspiratory (hiccup-like) response. These results indicated that PB-GPN is responsible for hiccup reflex.

Fear and stress reactions in two species of duck and their hybrid

Susceptibility to fear and stress has often been studied in birds using selection experiments. Crosses between different species of the same genus have also been used to study the type of transmission observed for “fixed action patterns.” In this experiment we used a cross between two species (male muscovy and female pekin ducks) to study the genetic transmission of various characteristics of fear reactions and adrenal activity. Males of the three genetic types (two parental species and the hybrid) were submitted to tonic immobility and fear of man tests. Blood was collected for corticosterone assay before and after physiological stress or injection of 5 μg/kg of immediate synacthen (ACTH agonist). The muscovy duck showed lower levels of fear reactions than the pekin duck in the majority of behavioral tests (six of eight). Corticosterone levels were also nearly always the lowest in muscovy ducks (five of six). Generally speaking, the muscovy duck appeared to be less fearful and less susceptible to stress than the pekin duck. The mule duck was similar to one parent, midway between the two, or showed heterosis for fear of man at 10 weeks of age (more fearful than the two parents). Corticosterone levels were midway between the two parents in the mule duck with only one exception, i.e., where the pekin duck was dominant. The existence of heterosis for fear is surprising, as this character is classically considered to be submitted to stabilizing selection. The transmission of corticosterone levels and other fear characteristics is, however, compatible with stabilizing selection. The results are discussed in terms of adaptability.

Intrasemiotics and cybersemiotics

The concept of intrasemiotics designates the semiosis of the interpenetration between the biological and psychological autopoietic systems as Luhmann defines them in his theory. Combining a Peircian concept of semiosis with Luhmann’s theory in the framework of biosemiotics makes it possible for us to view the interplay of mind and body as a sign play. The recently suggested term ‘sign play’ pertains to ecosemiotics processes between animals of the same species stretching Wittgenstein’s language concept into the animal world of signs. With intrasemiotics there is an inner interplay. Lorenz in ethology has used the concept of motivation, and Uexküll the concept of tone, mostly describing the outgoing effect on perception and the reactions on perception. One could view intrasemiotics as the interplay between Lorenz’ biologically defined motivations and Freud’s Id, understood as the psychological aspect of many of the natural drives. In the last years of development of his theory Lorenz studied how emotional feedback can introduce just a little learning through pleasurable feelings also into the instinctive systems because, as he reasoned, there must be some kind of reward going through instinctive movements, thus making the appetitive searching behaviour for sign stimuli possible. But he never found an acceptable way of modelling motivation in biological science. A cybersemiotic model may combine these approaches, defining various concepts of thoughtsemiotics, phenosemiotic and intrasemiotics, combining them with the already known concepts of exosemiotics, ecosemiotics, endosemiotics to an approach which studies the self-organising semiotic processes in living systems.

The eyes have it: a perceptual investigation of eyespots.

Previous work with non-human species has shown that eyespots function as sign stimuli for defensive behaviour. But it is unknown to what extent eyespots are a dominant feature of objects for human perceptual responses. We examined whether young children perceive eyespots as a dominant object feature. One hundred and nineteen children from the first, second, and third grades were presented with small manikins, called "Joopes" that varied in the number, type, and arrangement of facial features. Four kinds of Joope heads were used: single element (eyes, mouth, or beak only), monovalent (spatially concordant eyes and mouth, or eyes and beak), ambivalent (asymmetrical eyes and beak, or eyes and mouth), and cyclopean (single eye with orthogonal beak). Two task groups (Peepers and Gobs) 'helped' the Joopes to either 'see' their food or 'eat' it, by placing food in one of 24 feeding dishes. Results indicated that responses made to the ambivalent Joopes differed, with greater 'drift' shown by the 'eating' group towards the 'seeing' responses than by the 'seeing' group towards the 'eating' responses. The dominant role of eyespots was thus confirmed for children in the second and third grades, but response inconsistencies in the youngest group suggested difficulties in handling incongruent stimuli. The implications of these results for understanding basic perceptual processes are discussed.

Swimming behavior of the nudibranch Melibe leonina.

Swimming in the nudibranch Melibe leonina consists of five types of movements that occur in the following sequence: (1) withdrawal, (2) lateral flattening, (3) a series of lateral flexions, (4) unrolling and swinging, and (5) termination. Melibe swims spontaneously, as well as in response to different types of aversive stimuli. In this study, swimming was elicited by contact with the tube feet of the predatory sea star Pycnopodia helianthoides, pinching with forceps, or application of a 1 M KCl solution. During an episode of swimming, the duration of swim cycles (2.7 +/- 0.2 s [mean +/- SEM], n = 29) and the amplitude of lateral flexions remained relatively constant. However, the latency between the application of a stimulus and initiation of swimming was more variable, as was the duration of an episode of swimming. For example, when touched with a single tube foot from a sea star (n = 32), the latency to swim was 7.0 +/- 2.4 s, and swimming continued for 53.7 +/- 9.4 s, whereas application of KCl resulted in a longer latency to swim (22.3 +/- 4.5 s) and more prolonged swimming episodes (174.9 +/- 32.1 s). Swimming individuals tended to move in a direction perpendicular to the long axis of the foot, which propelled them laterally when they were oriented with the oral hood toward the surface of the water. The results of this study indicate that swimming in Melibe, like that in several other molluscs, is a stereotyped fixed action pattern that can be reliably elicited in the laboratory. These characteristics, along with the large identifiable neurons typical of many molluscs, make swimming in this nudibranch amenable to neuroethological analyses.

Social Interaction Over Time, Implications for Stress Responsiveness

Behavioral interaction during social situations is a continuum of action, response, and reaction. The temporal nature of social interaction creates a series of stressful situations, such as aggression, displacement from resources, and the variable psychological challenge of adapting to dynamic social hierarchies. The ebb and flow of neurochemical and endocrine secretions during social stress provide a unique tool for understanding individualized responses to stress. Each social station is an adaptive response to a stressful social condition, resulting in unique neuroendocrine and behavioral responses. By examining the temporal changes of limbic monoamines and plasma glucocorticoids, aspects of mechanisms for adaptation emerge. The similarity of temporal patterns induced by social stress among fish, reptiles and primates are remarkable. Even different specific coping mechanisms point out the similarity of vertebrate stress responses. The lizard Anolis carolinensis exhibits a unique sign stimulus generated during social stress by the sympathetic nervous system that serves as a temporal landmark to distinguish neuroendocrine patterns. During social interaction dominant males have a shorter latency to eyespot darkening than opponents, inhibiting aggressive display. Eyespot coloration can be delayed using a serotonin reuptake inhibitor, causing dominant social status in many animals to be lost. Reversal of social status via serotonergic activation appears to mimic chronic serotonergic activity. The pattern of eyespot darkening, faster in dominant males, is coincident with that for serotonergic activity. The fundamental temporal relationship between dominant and subordinate limbic monoaminergic activity over a continuous course of social interaction appears to be a two-phase response, temporally specific to brain region, and always faster in dominant individuals.

Contact chemoreception in feeding by phytophagous insects.

Gustatory receptors associated with feeding in phytophagous insects are broadly categorized as phagostimulatory or deterrent. No phytophagous insect is known that tastes all its essential nutrients, and the ability to discriminate between nutrients is limited. The insects acquire a nutritional balance largely "adventitiously" because leaves have an appropriate chemical composition. Sugars are the most important phagostimulants. Plant secondary compounds are most often deterrent but stimulate phagostimulatory cells if they serve as host-indicating sign stimuli, or if they are sequestered for defense or used as pheromone precursors. The stimulating effects of chemicals are greatly affected by other chemicals in mixtures like those to which the sensilla are normally exposed. Host plant selection depends on the balance of phagostimulatory and deterrent inputs with, in some oligophagous and monophagous species, a dominating role of a host-related chemical. Evolution of phytophagy has probably involved a change in emphasis in the gustatory system, not fundamentally new developments. The precise role of the gustatory systems remains unclear. In grasshoppers, it probably governs food selection and the amounts eaten, but in caterpillars there is some evidence that central feedbacks are also involved in regulating the amount eaten.

Kinematic Analysis of Suction Feeding in the Nurse Shark, Ginglymostoma cirratum (Orectolobiformes, Ginglymostomatidae)

Inertial suction feeding is known to occur in some sharks, but the sequence and temporal kinematics of head and jaw movements have not been defined. We investigated the feeding kinematics of a suction feeding shark, the nurse shark Ginglymostoma cirratum, to test for differences in the timing and magnitude of feeding components with other shark taxa when sharks were fed pieces of bony fish. Thirteen kinematic variables were measured from high-speed video recordings. Food capture in this species consists of expansive, compressive, and recovery phases, as in most other sharks, but there is little or no cranial elevation. Mean time to maximum gape (32 msec) is the fastest recorded for an elasmobranch fish. Other relatively rapid events include mandibular depression (26 msec), elevation (66 msec), and total bite time (100 msec). Buccal valves assist the unidirectional flow of water into the mouth and out of the gill chambers. Food capture under these experimental conditions appears to be a stereotyped modal action pattern but with significant interindividual variability in timing of kinematic events. Ginglymostoma cirratum exhibits a suite of specializations for inertial suction feeding that include (1) the formation of a small, anteriorly directed mouth that is approximately round and laterally enclosed by modified labial cartilages; (2) small teeth; (3) buccal valves to prevent the backflow of water; and (4) extremely rapid buccal expansion. Sharks that capture food by inertial suction have faster and more stereotyped capture behavior than sharks that primarily ram feed. Inertial suction feeding, which has evolved multiple times in sharks, represents an example of functional convergence with inertial suction feeding bony fishes.

Using the P300 Potential for the Analysis of Cognitive Functions in Children

In 84 healthy 5- to 15-year-old children, we studied the cognitive components of the evoked potentials elicited by acoustic stimulation, the P300 wave generated after presentation of a sign stimulus requiring the performance of sensorimotor reaction. We found a linear dependence of the peak latency of the P300 on the age of the tested persons (the latencies decreased with age). The amplitude of the P300 wave exhibited no clear dependence on the age (obviously, this parameter to a greater extent depends on other factors).

Ecosemiotics and cybersemiotics

The article develops a suggestion of how cybersemiotics is pertinent to ecosemiotics. Cybersemiotics uses Luhmann's triadic view of autopoietic systems (biological, psychological, and socio-communicative autopoiesis) and adopts his approach to communication within a biosemiotic framework. The following levels of exosemiosis and signification can be identified under the consideration of nonintentional signs, cybernetics, and information theory: (1) the socio-communicative level of self-conscious signification and language games. (2) the instinctual and species specific level of sign stimuli signifying through innate release response mechanism and sign games, and (3) the level of structural coupling, signal recognition, and languaging, where cybernetic feedback loops evince differences. Signification and communication levels arise whenever autopoietic systems interpenetrate (1) with the language system's semiotic and the psyche's phenosemiotic processes based on imaging, emotion, and volition and (2) between the psyche's phenosemiotic and the body's endosemiotic processes. It is at these two levels that we have the ecosemiotic signification processes of nonintentional signs in nature. Humans are linguistic cyborgs as animals are sign cyborgs because signs at different levels interpenetrate and form our embodied processes. Sign producing and interpreting capability has had selective influence on both animals and humans in evolution.

On the usefulness and limits of functional analogies.

Received: 9 January 2002 / Accepted: 14 January 2002 / Published online: 7 February 2002© Springer-Verlag 2002Comparison is the essence of science. But before anycomparison can be made one should extend one's knowl-edge of the subjects to be compared. We should be grate-ful to Bshary, Wickler, and Fricke (2002) for their com-prehensive review of cognitive processes in fish becausedespite its long history, this field has faced serious neglectin recent years. This lack of interest in fish cognition iseven more striking if one considers that all ethologistNobel Prize winners had some interest in fish behaviourduring their career, and much of this work is still cited intextbooks for students [e.g. von Frisch (1941): frightpheromons; Ter Pelkwijk and Tinbergen (1937): recogni-tion of sign stimuli)]. Unfortunately too many researchersinterested in cognitive processes in animals have turned tothe study of mammals, despite the fact that the laboratoryenvironment for the study can be made more natural forfish than for most mammals. Primates, especially, have re-ceived much attention from the scientific community, andalthough there are debates about the interpretation ofmany experimental results, primate cognition research isflourishing, and comprehensive reviews are published ona regular basis (e.g. Kohler 1925; Byrne and Whiten1988; Tomasello and Call 1997).Given the present situation, Bshary et al. (2002) did thebest they could by comparing many different skills in fishthat are thought to depend on cognitive processes withsimilar traits described for primates. They argued that fishcognition can and should be used as a null hypothesis forunderstanding primate cognition since most phenomenacan be found in both taxonomic groups, suggesting thatthe difference is only of a quantitative nature.However, apart from knowing our "subjects", for anyevolutionary comparison we should clarify the supposedrelationship between them. In comparative ethology, as inA. Miklosi (®)Dept. of Ethology, Eotvos University,Pazmany P. s. 1/c, 1117 Budapest, Hungarye-mail: miklosa@ludens.elte.hu,Tel.: +36-1-3812179, Fax: +36-1-3812179other biological sciences, such evolutionary comparisonsare based on the concept of homology and analogy (orconvergence). By homology we mean that there is somedetectable evolutionary relationship ("continuity") amongthese traits - in other words, one trait was presumably theantecedent of the others (in two different species). Analo-gies always describe the functional value of the traits oftwo species. In other words, it is supposed that similarecological constraints may lead to similar behaviouraltraits in a function, since this enables both species to sur-vive in a given environment. Since in evolution species-specific traits change over time, the detection of homolo-gies is getting more and more difficult. The opposite istrue for functional analogies, where a longer time on theevolutionary scale means an increased chance to developsimilarity. It should be noted, however, that functionalanalogy does not mean that the behaviour is served bysimilar underlying mechanisms. Nobody thinks that thebee dance informing companions about distance and di-rection of a food source is driven by the same behav-ioural/neural mechanisms used by humans when transmit-ting the same information using language. Nevertheless,in a sense bee dance and language can be regarded asfunctional analogies. The main question therefore is howfar one should stretch such a comparison, given that one'sinterest lies in the underlying mechanisms that govern thebehaviour.In the present case of animal cognition one might sup-pose that the building blocks of such abilities are stronglytied to the neural characteristics of neurons and are wellmodelled by the forms of associative learning. The ques-tion, then, is whether such similarity at the basic level ofneural organisation is enough to warrant a comparison be-tween these distantly related taxa. In other words, whatcan we gain by such comparative analysis?Part of my argument against this proposition relies onBshary et al.'s (2002) observation that in the primategroup one could pick many single species that have beenshown to have most of the traits investigated. In strongcontrast, in fish for many or most cases different specieshad to be used as the subjects of comparison. Although

Habituation and development of response specificity to a sign stimulus: male preference for female courtship posture in stickleback

I examined biased patterns of habituation that occur when reproductive male three-spined stickleback,Gasterosteus aculeatus , respond to a choice of two dummy females, one displaying the head-up posture of a sexually receptive female and an otherwise identical dummy lacking this sign stimulus (i.e. a dummy in a ‘neutral’ horizontal posture). Males initially courted both dummies about equally, but within 5min, their courtship to the horizontal dummy began to habituate and was eventually replaced by attack behaviour, which increased about four-fold during the 1-h trial. Courtship to the head-up dummy continued unabated throughout the trial and by 5min exceeded courtship to the horizontal dummy. Attack to the head-up dummy increased slightly in the first half of the trial then leveled off to about one-third that directed to the horizontal dummy. Both dummies were stationary and unreactive so could not directly provide differential feedback to the males. It is speculated that the self-arousal males obtain when responding to head-up posture reinforces their response to that cue. The salience of this sign stimulus may develop through an interactive process wherein the male's predisposition to recognize and court the head-up posture and the sexual self-arousal he obtains by doing so counter habituation and help maintain his sexual response to that cue. The stimulus–response specificity of male courtship is assumed to have an innate basis but requires experience to become fully differentiated. The results also illustrate that rate or extent of habituation to different stimuli, even on the same dimension, can differ within the same individual and in an adaptive manner.

Leaf cuticular waxes are arranged in chemically and mechanically distinct layers: evidence from Prunus laurocerasus L.

ABSTRACTThe composition and spatial arrangement of cuticular waxes on the leaves of Prunus laurocerasus were investigated. In the wax mixture, the triterpenoids ursolic acid and oleanolic acid as well as alkanes, fatty acids, aldehydes, primary alcohols and alcohol acetates were identified. The surface extraction of upper and lower leaf surfaces yielded 280 mg m−2 and 830 mg m−2, respectively. Protocols for the mechanical removal of waxes from the outermost layers of the cuticle were devised and evaluated. With the most selective of these methods, 130 mg m−2 of cuticular waxes could be removed from the adaxial surface before a sharp, physically resistant boundary was reached. Compounds thus obtained are interpreted as ‘epicuticular waxes’ with respect to their localization in a distinct layer on the surface of the cutin matrix. The epicuticular wax film can be transferred onto glass and visualized by scanning electron microscopy. Prunus laurocerasus epicuticular waxes consisted entirely of aliphatic compounds, whereas the remaining intracuticular waxes comprised 63% of triterpenoids. The ecological relevance of this layered structure for recognition by phytotrophic fungi and herbivorous insects that probe the surface composition for sign stimuli is discussed.

Species-Specific Female Cues Control Conditioned Sexual Approach of Male Japanese Quail (Coturnix japonica)

Adult male Japanese quail (Coturnix japonica) use visual species-specific cues to discriminate the sex of conspecifics. For example, male Japanese quail demonstrate social proximity to female, but not male quail, if they are allowed to copulate with female quail and receive noncopulatory exposures to males. In the present study, species-specific female cues were used to investigate learning about sign stimuli in a sexual Pavlovian conditioning paradigm. Copulation with a female taxidermic model (US) was paired with a previously neutral block of wood (CS). After several trials, paired subjects came to approach the block of wood. The findings indicate that a female taxidermic model containing speciesspecific sign stimuli can serve as an effective US. In addition, female sign stimuli may play an important role in the acquisition of sexually conditioned responses.

Possible role of neuropeptides in obsessive compulsive disorder.

The most consistent finding in clinical research of obsessive compulsive disorder (OCD) is the significant treatment advantage of potent serotonin uptake inhibitors (SUIs) over other classes of antidepressant and antianxiety drugs. Clinical neurobiological studies of OCD, however, have yielded limited and inconsistent evidence for significant fundamental abnormalities in monoamine systems including serotonin, norepinephrine and dopamine. Furthermore, one-third to one-half of OCD patients do not experience a clinically meaningful improvement with SUI treatment. Investigation beyond the monoamine systems may be necessary in order to more fully understand the pathophysiology of obsessive-compulsive symptoms and develop improved treatments. Evidence from preclinical studies suggests that neuropeptides may have important influences on memory acquisition, maintenance and retrieval; grooming, maternal, sexual and aggressive behavior; fixed action patterns; and stereotyped behavior; these phenomena may relate to some features of OCD. In addition, extensive interactions have been identified in the brain between neuropeptidergic and monoaminergic systems, including co-localization among specific populations of neurons. The purpose of this review is to present the current knowledge of the role of neuropeptides in the clinical neurobiology of children, adolescents and adults with OCD focusing primarily on results from pharmacological challenge and cerebrospinal fluid studies. Where evidence exists, developmentally regulated differences in neuropeptide function between children and adolescents versus adults with OCD will be emphasized; these data are intended to underscore the potential importance of establishing the age of symptom onset (childhood versus adult) in individual patients with OCD participating in clinical neurobiological investigations. Likewise, where information is available, differences in measures of neuropeptides between patients with non-tic-related OCD versus tic-related OCD will be highlighted; these data will demonstrate the critical value of diagnostic precision, as these two particular subtypes of OCD may have different neurochemical underpinnings.

Bird repellents: development of avian-specific tear gases for resolution of human–wildlife conflicts

The use of bird repellents may be required when human activities place birds in danger, e.g., hazardous waste sites, or when birds cause damage to crops, architectural structures, or are a source of zoonotic disease. Typical protective measures to keep birds away from areas include exclusion by use of netting, hazing (i.e., scaring tactics) and chemical repellents. Birds can rapidly habituate to visual and auditory hazing if the use of these tactics falls into a predictable pattern, or if the sign stimuli are not coupled with a salient aversive reinforcing stimulus. Chemical repellents are typically used to render a resource unpalatable and, as a consequence, create a disincentive for a bird to visit a particular area. Methyl anthranilate (MA) is a potent avian chemosensory irritant. In this paper, we explore the possibility of employing MA aerosols as a bird deterrent strategy. We determine the behavioral response of starlings ( Sturnus vulgaris) to each of three aerosols: water or yucca extract (controls) and ReJeX-iT TP-40 TM (a 40% MA solution), and found that starlings were irritated by exposure to the MA aerosol. Moreover, starlings did not habituate to repeated exposure to MA aerosols. We determined in the laboratory that the starlings threshold for irritation to a formulated aerosol was 8% MA.

P1D95 - Gonadal and reproductive capacity under conditions of radiation background increase

Effects of the anxioselective anxiolytic abecarnil, a β-carboline benzodiazepine-receptor agonist, on initial licking responses for a 3% sucrose solution and on taste reactivity responses were evaluated in adult male rats. The rats' behaviour was video recorded, and analysed according to a frame-by-frame procedure to generate the durations of categorized fixed action patterns, and the number and rate of licking responses. The results indicated that abecarnil (0.3–3.0 mg/kg, i.p.) significantly increased the number of licks in the first continuous sample of licking, while significantly reducing the lick rate (licks/s). Additionally, abecarnil selectively enhanced positive ingestive responses, but had no effect on either neutral or aversive response categories in taste reactivity measures. On the basis on this pattern of results, we conclude that abecarnil can enhance taste palatability selectively, and that it may act as an agonist at GABAA benzodiazepine receptor subtypes which mediate drug effects on ingestive behaviour.

The Value of Being a Resource Specialist: Behavioral Support for a Neural Hypothesis

The neural hypothesis of diet breadth proposes that selecting an appropriate behavior is more efficient if simple or exaggerated cues can be used as a basis of decision making rather than making a choice among many complex sensory inputs. I propose that simple signals overcome the problem of multiple sensory inputs and the consequent need for the brain to decide among inputs from these multiple channels. Experiments on grasshoppers show that there is a significant time cost in having to make a choice, relative to situations in which individuals have grown accustomed to having no choice. Those with a choice were shown to be less decisive by two different measures than those without a choice. It is argued that the data, showing lengthy decision times as a result of having a choice, would involve a significant ecological risk. It is further argued that the reduced risk of quick decisions would favor specialization of resource use. The evolution of resource-specific cues that have often been called sign stimuli are considered critical elements of restricted resource use.

GABAergic inhibition of hiccup-like reflex induced by electrical stimulation in medulla of cats

We hypothesize that the hiccup reflex is actively inhibited through GABA B receptor within central connections of the hiccup reflex arc. Because the hiccup-like reflex can be elicited by electrical stimulation to a limited area within the medullary reticular formation, the hiccup-evoking site (HES), electrical stimulation (50–100 μA, three train pulses at 20 Hz) was delivered to HES by means of a metal electrode containing 1.0 mM baclofen, in anesthetized spontaneously breathing cats. The evoked response was characterized by a brief powerful increase in diaphragmatic activity and a temporal suppression of the posterior cricoarytenoid muscle, laryngeal dilator, which corresponded to the fixed motor pattern of hiccup reflex. The hiccup-like response was rapidly suppressed after microinjection of baclofen (0.1–0.5 nmol) into HES, indicating that HES has GABA B receptors. In the other experiments, to histologically examine the inputs to the hiccup reflex arc, unconjugated cholera toxin subunit B (UCTB) was injected into HES. Following injections of UCTB, retrogradely labelled cells were found distributed in various areas of the lower brainstem. Among these areas, the nucleus raphe magnus (RM) is reported to have GABA-containing cells. It is thus hypothesized that RM is most likely to be the source of the GABAergic inhibitory inputs to the hiccup reflex arc.

Erection Evoked in Male Rats by Airborne Scent from Estrous Females

In the presence of inaccessible estrous females, male rats display penile erections and associated stereotypic behavior indicative of sexual arousal. The effective stimuli for these noncontact erections (NCEs) had not been determined, but bedding soiled by estrous females was known to be ineffective. The present experiments tested for a potential role for volatile olfactory cues in evoking NCE. In Experiment 1, sexually naive male rats were observed for NCEs when tested with inaccessible, estrous females upwind ( n = 20) or downwind ( n = 20) from them under conditions that permitted or prevented visual communication. After half the males in each condition had copulatory experience, they were retested under the same conditions. In each test, only one male of 20 responded with females downwind, whereas about half the 20 males displayed NCEs with females upwind, irrespective of barrier type or, in Test 2, of sexual experience. Olfactory cues from estrous females were apparently necessary to induce NCE, whereas visual and auditory stimuli from estrous females were not sufficient to evoke NCE, nor did they affect the response to olfactory stimulation. In Experiment 2, males were downwind from estrous females ( n = 10) or anestrous females ( n = 10) that were behind opaque barriers and were anesthetized to preclude auditory communication. Results indicated that olfactory cues were also sufficient to provoke NCE in sexually experienced males. Receptive female rats apparently broadcast a volatile pheromone that promotes erection. Pheromones are well known to attract potential mates and to act in concert with other stimuli to promote mating. However, this is the first mammalian evidence for a volatile pheromone acting alone to evoke a sexual fixed-action pattern and, in that sense, acting as an airborne aphrodisiac.