Chemosensory Stimulation Research Articles

Intersensory experience and early perceptual development: Attenuated prenatal sensory stimulation affects postnatal auditory and visual responsiveness in bobwhite quail chicks (Colinus virginianus).

Related experiments examined the effects of attenuated prenatal sensory stimulation on subsequent postnatal auditory and visual responsiveness in precocial bobwhite quail chicks {Colinus virginianus). Results revealed that denying quail embryos the prenatal vestibular and tactile stimulation provided by broodmates during incubation alters pre- and postnatal perceptual functioning. Chicks incubated in physical isolation during the late stages of prenatal development responded to maternal auditory cues into later stages of the postnatal period and failed to respond to maternal visual cues at ages communally incubated chicks typically display such visual responsiveness. In addition, embryos incubated in physical isolation failed to exhibit early auditory learning of an individual maternal call, a behavior reliably seen in communally incubated embryos. Taken together, these results and those from related studies indicate that a substantial decrease or increase in the range of sensory stimulation normally present in the prenatal period can result in a slowing of the rate of speciesspecific perceptual development and suggest that some optimal range of prenatal sensory stimulation is necessary for species-typical perceptual capacities to emerge. The prenatal environment of avian and mammalian species is rich in tactile, vestibular, chemical, and auditory sensory stimulation (Freeman & Vince, 1974; Ronca, Lamkin, & Alberts, 1993; Smotherman & Robinson, 1986). In many species, the sensory systems capable of responding to these types of inputs are already well developed and functional before birth or hatching (Alberts, 1984; Bradley & Mistretta, 1975; Gottlieb, 1971). The availability of a rich sensory environment during the prenatal period, coupled with the embryo or fetus's capacity to respond to it, suggests that the development of early perceptual organization may be strongly influenced by prenatal sensory experience. In this light, several studies have shown that the human fetus is sensitive and responsive to auditory stimulation and can retain the effects of prenatal auditory experience into postnatal life (DeCasper & Spence, 1991; Fifer & Moon, 1988). Studies with both infrahuman mammalian species and human fetuses have also shown that prenatal experience with chemosensory stimulation can exert significant effects on subsequent postnatal behavior. For example, Smotherman and

Tachykinin antagonists in carotid body responses to hypoxia and subtance P in the rat

In the present study, we tested the hypothesis that substance P (SP) is an excitatory peptide to the rat carotid body and plays an important role in chemosensory excitation by hypoxia. Chemosensory discharge was recorded from the cut carotid sinus nerve in 19 anaesthetized, paralyzed and mechanically ventilated rats. Intracarotid admininstration of SP augmented the chemoreceptor activity in a dose-dependent manner. Maximal excitation was seen with 10 nmol SP. Carotid body stimulation by SP was independent of its effects on arterial blood pressure. The effect of SP antagonist, D-Pro 2-D-Trp 7.9-SP (DPDT-SP) or Spantide, on chemoreceptor responses to SP and hypoxia was examined in 12 rats. Close carotid body administration of either at doses of 40 μg·kg −1·min −1 elicited an augmentation followed by a progressive depression of baseline carotid body activity. SP antagonists significantly reduced peptide-induced carotid body stimulation and also markedly attenuated the chemoreceptor response to hypoxia. Systemic administration of sodium bicarbonate stimulated the carotid bodies, presumably by releasing CO 2, and the bicarbonate-induced chemoreceptor stimulation was not affected by SP antagonists. From the results the conclude that in rats (a) SP stimulates the carotid bodies independently of its effects on arterial blood pressure, and (b) SP is associated with the chemosensory stimulation by hypoxia but not with other excitatory stimuli.

Effects of chemosensory stimulation membrane currents recorded with the perforated-patch method from cultured rat glomus cells.

We are using primary cultures of dissociated cells from the rat carotid body to study chemotransduction mechanisms. A major focus has been the electrophysiological characterization of the glomus (or type 1) cells which are the presumed sensors of the chemosensory stimuli, hypoxia, hypercapnia, and acidity (Biscoe and Duchen 1990; Lopez-Barneo et al 1988; Stea and Nurse 1991a; etc.). Using the giga-seal patch-clamp technique (Hamill et al 1981) we have determined that cultured rat glomus cells have membrane currents similar to those found in freshly-isolated rabbit glomus cells (Duchen et al 1988; Lopez-Lopez et al 1989; Hescheler et al 1989; see also, Peers 1990). The implementation of the novel perforated-patch recording method (Horn and Marty 1988) in many of our studies has circumvented problems associated with conventional whole cell recording such as washout of important cytoplasmic constituents, and rapid deterioration of the preparation.KeywordsCarotid BodyMembrane CurrentGlomus CellChemoreceptor CellCytoplasmic AcidificationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Habituation in the rat fetus.

Rat fetuses exhibit motor and cardiac responses to chemosensory stimulation on Days 20 and 21 of gestation. The first experiment demonstrated that fetuses exhibit an increase in overall motor activity and decrease in heartrate in response to an initial intraoral infusion of a lemon solution. After a series of nine exposures, however, fetuses no longer exhibit motor or cardiac responses to lemon infusion, suggesting the existence of a habituation-like process. Responsiveness recovers spontaneously following a 3- to 9-min period without stimulation. In a second experiment, a dishabituation treatment was administered to distinguish habituation, which is a centrally mediated decrement in response, from effector fatigue, sensory adaptation, and other peripheral mechanisms that can result in reduced responsiveness. A single infusion of mint following a series of nine lemon exposures was effective in reinstating fetal motor responses to lemon on both Days 20 and 21, but reinstated cardiac responses only on Day 21. Rat fetuses habituate to repeated chemosensory stimulation, suggesting the utility of the habituation paradigm in measuring CNS development during the perinatal period.

Heart rate response of the rat fetus and neonate to a chemosensory stimulus

Resting heart rate (HR) and HR responses of fetal and neonatal rats are described before and after intraoral infusion of isotonic saline or lemon solution. Stable measurements of resting HR were obtained for fetuses over the last three days of gestation (E19, E20, E21) and pups on the day of birth (P0) and four subsequent postnatal ages (P1, P3, P5, P7). Resting HR decreased significantly on P0 relative to the three prenatal ages and exhibited a linear increase thereafter. Variability in resting HR was pronounced on E21, decreased sharply after birth, and gradually increased through P7. Developmental changes in the HR response of fetuses and pups were evident following infusion of lemon. Fetal HR responses to lemon were characterized by bradycardia, which increased in magnitude through P1, diminished after P1, and eventually changed to tachycardia by P7. Both resting HR and HR responses to chemosensory stimulation point to the immediate perinatal period as a time of quantitative and qualitative change during sensory development.

Carotid chemosensory timing effects on cervical sympathetic discharges in the cat

The hypothesis that respiratory phase-related sympathetic nerve activity would manifest timing effect of carotid chemosensory input with respect to the central respiratory drive was tested in the anesthetized, paralyzed and artificially ventilated cats which were also vagotomized and tracheostomized. Preganglionic cervical sympathetic nerve fibers (PSNF) which were clearly responsive to carotid chemosensory stimulation were selected for the test. Simultaneously with the PSNF, phrenic nerve (PN) and internal intercostal expiratory nerve (IICEN) activities were also recorded. In most instances, carotid chemosensory discharges were monitored in order to register the precise timing of its input to the brain-stem. Timed stimulation of carotid chemoreceptors was elicited by bolus injections of cyanide (10–20 μg), nicotine (10–20 μg) and CO 2-saturated saline (0.2–0.5 ml) into the base of the common carotid artery. Two types of PSNFs were identified: type I discharged only in synchrony with the PN activity ( 13 47 ) and type II fired independently of, but entrained to, PN activity ( 34 47 ). Type I displayed characteristic timing effects of carotid chemoreflex on PN discharges. However, the sympathetic activity did not share the after-discharge of PN which persisted beyond the carotid chemoreceptor stimulation. Type II did not manifest any timing effect of carotid chemoflex with respect to PN and IICEN activities. These results suggest the following model of carotid chemoreflex effects on sympathetic neuron activities: a group is exclusively gated by the properties of central respiratory drive whereas the other is not gated but entrained by it in the spontaneously breathing anesthetized cat.

Association between chemosensory stimuli and cesarean delivery in rat fetuses: Neonatal presentation of similar stimuli increases motor activity

Recent studies conducted in this laboratory indicated that prenatal chemosensory stimulation followed by cesarean delivery strongly affected postnatal responsiveness to odors derived from the administered substances. The present experiments were performed in order to examine if an associative process was responsible for such effects. In Experiment 1 rat fetuses during Gestational Day 21 were exposed to a tenuous alcohol solution or to a lemon-containing solution either 40 or 10 min prior to cesarean delivery. All subjects were subsequently tested in terms of changes in neonatal motor activity when confronted with the odor of alcohol or lemon. Rats experiencing prenatal cues 10 min prior to delivery exhibited higher and differential responsiveness to the smell of these cues when compared to those experiencing similar solutions 40 min prior to delivery. In Experiment 2 each fetus sequentially experienced both cues. Subsequent tests confirmed that the delay between prenatal sensory experience and birth induction was critical in terms of significantly affecting olfactory-mediated motor responses. The results suggest that consequences related with cesarean delivery act as an unconditioned stimulus capable of being associated with orosensory cues present in the amniotic fluid.

A new method for delivering a taste without fluids to preterm and term infants

A new method for administering a taste to preterm and term infants has been developed that does not necessitate the delivery of rapid solutions. Sucrose, a sugar that in solution was shown to potentiate sucking behavior, was embedded in gelatin-based nipples that continuously release sweet taste when mouthed or sucked. The gelatin nipples and comparable latex nipples were adapted to measure sucking behavior and were tested in a within-subject design. The gelatin nipples potentiated sucking in preterm and term infants by increasing the frequency and strength of the responses. Few sucking measures varied significantly for preterm and term infants. Those that did vary might be attributable to differences in physical stamina, rather than to orosensory or hedonic factors. It was concluded that the flavored gelatin nipple provides an effective method for studying taste in infants and offers the possibility of routine chemosensory stimulation for research and clinical applications.

Chemosensory conditioning of Hermissenda crassicornis.

Bite-strike responses of Hermissenda crassicornis, elicited by chemosensory stimulation of the lips, were found to be modified when food extracts were paired with rotation-produced stimulation of the statocysts. Animals that received repeated pairings of an extract of 1 food (conditioned stimulus, CS) with rotation exhibited suppressed bite-strike responses to that food for up to 48 hr after training. This suppression was usually specific to the trained food and was pairing-specific as well. Discriminative conditioning was also demonstrated. Animals trained with 1 CS paired with rotation and a second CS that was unpaired (CS-) showed suppressed bite-strike responses to the first CS. The results demonstrate that Hermissenda can learn to avoid foods that reliably signal an aversive event and may allow an analysis of higher order conditioning phenomena.

Brain electrical activity topographical maps produced in response to olfactory and chemosensory stimulation

Brain electrical activity topographical maps produced in response to olfactory and chemosensory stimulation

Reflex cardiac response to a feeding stimulus in the blowfly Calliphora vomitoria L.

Evidence is presented on the effectiveness of taste chemosensory stimulation in evoking reflex heart-beat reversal in the blowfly, Calliphora vomitoria L. Electrophysiological activity of the heart and input from stimulated taste sensilla were simultaneously recorded in intact and operated insects. The reflex cardiac response to taste stimulation could still be evoked in headless flies and after transection at the abdominal level of nerve fibres running to the heart. Upon repeated stimulation, the cardiac reflex was abolished in intact insects, while it was persistently evoked even on performing iterative stimulations in operated insects. It is suggested that cephalic ganglia regulate the degree of excitation of the thoracicoabdominal ganglion which, on the incoming input from taste chemosensilla, actually promotes reflex heart-beat reversal in this insect.

Analysis of the catnip reaction: mediation by olfactory system, not vomeronasal organ

Pet owners and behavioral scientists alike are fascinated by unique behavioral reactions that cats show in the presence of catnip. These experiments explored the possibility that the catnip reaction might be triggered by chemosensory stimulation of the vomeronasal organ. In the chewing and mouthing of the catnip source, substances might be dissolved in saliva and transported to the vomeronasal organ. The rolling and rubbing during a catnip reaction might be a sexual response activated by the accessory olfactory system since the system projects to parts of the brain involved in mediation of sexual behavior. However, removal of the vomeronasal organ did not attenuate any of the behavioral reactions to catnip. Olfactory bulbectomy immediately eliminated catnip responding, revealing that the chemosensory stimulus evoking the catnip reaction is undoubtedly mediated through the main olfactory system. Catnip activates behavioral elements associated with several species-specific behaviors, including sniffing and chewing as associated with oral appetitive behavior, rolling and rubbing characteristic of female sexual behavior, batting the catnip source characteristic of play behavior, and a type of kicking associated with predatory behavior. These behavioral reactions occur randomly and intermittently.

Swimming pattern as an indicator of the roles of copepod sensory systems in the recognition of food

The roles of copepod sensory systems in the recognition of food were investigated using the “Bugwatcher”, a video-computer system designed to track and describe quantitatively the swimming patterns of aquatic organisms. The swimming behavior of the copepodPseudocalanus minutus in the presence of phytoplankton is characterized by a decrease in average swimming speed and an increase in “pause” behaviors compared to its swimming behavior in filtered seawater. Copepods exposed to chemosensory stimulation alone (filtered phytoplankton exudate) exhibited an increase in average swimming speed and an increase in the number of “burst” swimming behaviors. When exposed to a novel, non-food chemosensory stimulus (morpholine), no change in swimming behavior was observed unless the copepods had been conditioned to this odor in the presence of phytoplankton. Copepods exposed to mechanosensory stimulation alone (plastic spheres) exhibited a decrease in swimming speed and an increase in pause behaviors. When exposed to both forms of stimulation simultaneously (phytoplankton exudate and plastic spheres), a further decrease in swimming speed and increase in pause behaviors occurs, yielding a swimming pattern similar to that found in the presence of phytoplankton. This analysis of swimming pattern indicates that both chemoreception and mechanoreception contribute to the recognition of food inP. minutus.

Neurobiology of the scallop. I. Starfish-mediated escape behaviours

(i) In the scallop Pecten ziczac , escape responses triggered by the chemosensory stimulus of a starfish are highly stereotyped and reproducible. These responses are characterized either as jumps, i. e. single, rapid valve closures, or as swims consisting of a rapid sequence of valve closures. Jumps are evoked by a starfish stimulus to the lateral and ventral mantle edges, regions innervated by pallial nerves extending from the parietovisceral ganglion. Swimming is triggered specifically by a stimulus at or near the dorsal ‘ears’ of the shell, regions innervated by pallial nerves from the cerebral ganglion. (ii) Escape responses begin with a characteristic gaping of the valves. Evidence from simultaneous recordings of shell movement, and from electrical activity in the smooth muscle and its efferent nerve, has demonstrated that the relaxation of the smooth adductor muscle responsible for valve gape is an active process mediated by efferent discharges from the parietovisceral ganglion. Sustained valve adductions evoked by direct electrical stimulation of the smooth muscle can also be voluntarily relaxed by efferent control. The ‘resting’ tension of the smooth muscle that normally maintains the partially adducted ( ca . 50 %) shell posture is not a result of tonic efferent activity. Denervation of the smooth muscle eliminates the opening phase of escape responses and all other slow valve adductions. The resulting shell posture, however, is equivalent to that maintained normally by the intact scallop during periods of inactivity. Swim responses in the smooth muscle-denervated scallop passively reset the smooth muscle to shorter lengths. The valves then gradually reopen, due to the force of the compressed hinge resilium, although at a much slower rate than typically occurs in the intact scallop. These results indicate that the smooth muscle normally exists in a ‘catch ’ state, and that catch must be actively released during swimming and at the beginning of an escape response. (iii) Contraction of the smooth adductor muscle is timed closely with that of the striated muscle in the jump response, but is delayed until the end of the swim cycle. As a result, all escape behaviours terminate with a slow reopening of the valves due to the slow relaxation properties of the smooth muscle. Repetitive swim-like responses can be evoked under a variety of experimental circumstances that would eliminate feedback from putative stretch receptors in the adductor muscle. Rapid jump and swim adductions are therefore not due to stretch receptor feedback upon motor nerves innervating the striated muscle, and jumps and swims are not terminated as a result of sustained adductions, which would interrupt a stretch receptor reflex cycle. (iv) Escape by swimming is the result of a central motor programme, the behavioural expression of which depends on the site of peripheral chemosensory stimulation. This programme coordinates excitatory efferent activity in the smooth and striated adductor muscles, in addition to efferent control of smooth muscle catch and relaxation. Transection of the cerebrovisceral connectives eliminates all repetitive swimming activity and blocks relaxation of the smooth muscle; only jumps remain. There­fore, although the efferent nerves, and presumably their oscillatory activity, originate in the parietovisceral ganglion, the high-level control of escape behaviour resides in the cerebral ganglion.

Chemosensory stimulation of the oral cavity of the snail Helisoma

Chemosensory stimulation of the oral cavity of the snail <i>Helisoma</i>

Role of interganglionic synaptic connections in the control of pedal and parapodial movements in Aplysia

Locomotion in Aplysia can be elicited by food chemosensory, tactile, proprioceptive and nociceptive stimuli. The effects of these stimuli on cerebral B neurons, pleural neurons and motor activity in the foot were examined and the behavioral roles of identified synaptic connections among these neurons investigated in semi-intact preparations. The motor effects of intracellular stimulation of pleural neurons were determined. Sensory stimulation elicited spiking in the left giant cell (LGC) in quiescent preparations. When the LGC was spontaneously bursting, sensory stimulation caused decreased interburst intervals and increased burst durations. Following sensory stimulation, LGC firing was correlated with motor activity in the foot. Intracellular stimulation of the LGC evoked contractions in the foot and parapodia. Pleural neurons which produced EPSPs in the LGC and/or B neurons were excited by sensory stimuli that elicit locomotion and when driven caused contractions in the foot. Pleural neurons which inhibited the B neurons were excited by nociceptive stimuli that inhibit normal locomotion, and were inhibited by tactile and chemosensory stimulation of the tentacles which excited the B neurons and can elicit normal locomotion. Intracellular stimulation of the neurons which produced IPSPs in the B neurons evoked contractions in the posterior foot suggesting a motor function in nociceptive induced withdrawal. The synaptic connections between pleural and cerebral neurons are consistent with the proposed modulatory role of the pleural ganglion in locomotion, and may account for changes in locomotion with result from cerebro-pleural connective lesions.

A microelectrode for measuring intracellular PO2.

A simple and reliable method of constructing an intracellular pH microelectrode is described. Antimony is used as the pH sensor. Antimony electrodes have been used in biological systems as early as 1927 (1). Since then several investigators have used different kinds of Sb electrodes. Roos and Boton (3) describe the latest methods of construction and application of pH sensitive micro-electrodes. In most cases the pH electrodes were fabricated by pulling glass capillaries filled with molten antimony and in a few cases by coating glass with antimony. The electrodes were of the open type.