Detection versus perception: Physiological and behavioral analysis of olfactory sensitivity in the moth (Manduca sexta).

The precise relationship between olfactory transduction sensitivity and sensitivity at the level of sensory perception is poorly understood. The goal of this work was to correlate neurophysiological measures of sensory transduction and psychophysical measures of salient odor perception using the moth (Manduca sexta). Moths were conditioned to respond to a single monomolecular odor and then tested across a dilution series. Resulting concentration-response functions were dependent on the conditioning odor and its concentration but not on the moth's sex. Comparison of responsiveness to odor versus an odorless blank provided a statistical indicator of detection threshold. Separate control experiments revealed that conditioned responsiveness to odor was a function of test concentration and independent of the conditioning concentration. Next, electroantennogram (EAG) responses to these odorants and concentrations were recorded. EAG responses were highly correlated with the behavioral results but typically identified lower detection thresholds. Furthermore, significant effects of sex, Sex × Odor, and Sex × Odor × Concentration were observed only within the EAG data, suggesting a mismatch across methods. Possible reasons for and implications of this mismatch are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Habituation and dishabituation of the proleg withdrawal reflex in larvae of the sphinx hawk, Manduca sexta.

The neural circuit for the proleg withdrawal reflex (PWR) of Manduca sexta larvae exhibits activity-dependent plasticity. This study demonstrates habituation and dishabituation of PWR behavior. Repeated deflection of 1 or 5 mechanosensory hairs on a proleg at a 60-sec interstimulus interval (ISI) for 20 trials produced a significant decrease in evoked force of proleg withdrawal. Habituation was similar with 30-sec and 60-sec ISls and nonsignificant with a 5-min ISI or without repeated stimulation. Habituated responses recovered after cessation of stimulation or pinch of the body wall (dishabituation). The role of intersegmental influences was tested by severing connectives to leave different numbers of ganglia connected to the test segment. Habituation was robust even in test segments that were disconnected from the rest of the central nervous system. The PWR of Manduca is appropriate for further analysis of cellular mechanisms underlying learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Poison-based taste aversion learning in deer mice (Peromyscus maniculatus bairdi).

Used a series of experiments to test the ability of 219 adult Peromyscus mice to form learned taste aversions. It was found that (a) the mice acquired a strong aversion after a single flavor/toxicosis pairing, (b) naive mice drinking a LiCl solution apparently began to experience toxic effects within 90 sec after the beginning of consumption, (c) the mice acquired a total aversion after a single flavor/delayed illness pairing when high doses of toxin were employed, and (d) the aversion produced by a single flavor/delayed-illness pairing was specific to the flavor paired with illness and was dependent on the contingency between the flavor and illness. Although these responses are qualitatively similar to those reported for domestic rats, the mice formed considerably weaker aversions than those previously reported for laboratory rats tested with the same weight-specific doses of LiCl. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contribution of nesting experience to progesterone-induced incubation in ring doves (Streptopelia risoria).

Examined whether exposure of 60 ring doves to progesterone during the nest-building phase would be sufficient to account for the ability of progesterone to induce incubation at a later time or whether some other factor provided by nest-building experience with this phase of the cycle would be needed. Six groups of 10 pairs of Ss each were provided with different combinations of experience and progesterone priming. Progesterone priming (100 μg for 4 days), combined with social isolation or with courtship experience, had no significant effect on subsequent progesterone-induced incubation. However, Ss that participated in the nesting phase of the cycle during progesterone priming later incubated in response to progesterone treatment. Nesting activity, which did or did not include building the nest, seemed to be the relevant experience. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motivational influences underlying prolactin-induced feeding in doves (Streptopelia risoria).

Prolactin (Prl) increases food consumption in ring doves (Streptopelia risoria) and may promote the hyperphagia exhibited by parent doves when provisioning young. These experiments tested whether Prl also enhances appetitive aspects of feeding behavior. Prl elevated pecking rates in food-restricted doves on a variable-interval (VI) reinforcement schedule and supported continued responding when doves were returned to ad-lib feeding. Prl-treated doves learned the key-pecking response when food intake was clamped at ad-lib levels exhibited before Prl treatment but not when given free access to food. Median break points on a progressive ratio schedule were 2–3 times greater in food-restricted doves than Prl-treated, food-clamped doves even though response rates were similar on VI schedules. These results indicate that Prl enhances appetitive aspects of feeding, although food restriction at the level imposed in this study was more effective in this regard. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latent inhibition experiments with goldfish (Carassius auratus).

Examined evidence of latent inhibition in a series of experiments with goldfish. In Exp I, 12 Ss were given nonreinforced preexposure to a color that subsequently predicted shock in an activity conditioning situation; their performance did not differ from that of 12 control Ss preexposed to a markedly different color. In Exp II, 12 Ss given nonreinforced preexposure to a tone and an unstimulated control group of 12 Ss were trained in an appetitive situation, with the tone serving either as a conditioned excitor or as a conditioned inhibitor. Preexposure had significant effect in the conditioned excitation training, but it reduced the level of responding both to the positive stimulus and to the negative compound in the conditioned inhibition training. In Exps III and IV, classical aversive conditioning was studied in the shuttle box. In Exp III, excitatory conditioning to a color was found to be impaired (relative to the performance of nonpreexposed control Ss) as much by nonreinforced preexposure to the training color as by nonreinforced preexposure to a markedly different color; substantial variation in amount of preexposure was without significant effect. In the conditioned inhibition training of Exp IV, 12 Ss with nonreinforced preexposure responded less than did 12 unstimulated control Ss, both to the positive stimulus and to the negative compound. Results demonstrate that the effect of preexposure on goldfish is their reduction of general responsiveness or level of arousal. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A failure to find socially mediated taste aversion learning in Norway rats (R. norvegicus).

Three studies with 240 Long-Evans rats investigated whether rats would avoid ingesting a diet as the result of interacting with an ill conspecific that had ingested that diet. Observer rats interacted with conspecific demonstrators immediately after demonstrators ate a novel diet and were made ill by LiCl injection. Following their interaction with demonstrators, observers were tested for aversion to their ill demonstrator's diet. Previous research has shown that (a) an observer can extract information from a demonstrator sufficient to permit identification of the demonstrator's diet and (b) a rat ill from LiCl toxicosis is an adequate UCS in a taste aversion learning paradigm. Two of the present experiments demonstrated that cues emitted by an S, reflecting the particular diet it has eaten, were an adequate CS in a toxicosis-induced aversion learning situation. Observer avoidance of a diet previously ingested by an ill demonstrator was, however, not demonstrated. Implications of the failure to find socially mediated aversion learning are discussed. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparisons of feeding behavior in captive squirrel and titi monkeys (Saimiri sciureus and Callicebus moloch).

In view of behavioral differences observed in natural environments, one might expect that feeding and foraging patterns draw on different behavioral tendencies in squirrel and titi monkeys. Some of these tendencies were identified in the present 4 studies. In the home cage and in the presence of abundant food, squirrel monkeys were rapid, wasteful, and relatively asocial feeders. Titis in the same setting were slower, more selective, thorough, and socially involved feeders. Passive sharing of food between titi pair-mates was common. When competition was increased by presenting a single food item, titis continued to rely on positive social interactions to obtain food; squirrel monkeys still relied mainly on asocial stratagems to obtain food. The species' food preferences in paired-comparison tests were quite similar, although their patterns of obtaining and consuming the foods were not. Squirrel monkeys took food more quickly but consumed less than titis. When the same foods were presented repetitively, squirrel monkeys remained more wasteful consumers and were satiated more quickly than titis, even with highly preferred foods. These differences are discussed in terms of their probable contributions to each species' modal foraging patterns in natural environments. The findings are placed in an adaptive profile framework for each species, based on data accumulated in a series of studies conducted over the last decade. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trigeminal deafferentation and feeding behavior patterns in the pigeon (Columba livia).

Data from a study with 11 White Carneaux pigeons show that after an aphagic period, trigeminally deafferented Ss regulated body weight at reduced levels. The deficit involved was characterized by comparing feeding patterns of deafferented and food-deprived birds with equivalent weight losses. Deafferented Ss showed disproportionate increases in meal size during the early portion of the feeding period but abnormally rapid attenuation of feeding activity in the course of the day, which led to a reduced overall level of food intake. Trigeminal input appears to influence both the size of bouts and the frequency of bout initiation. Findings are discussed in relation to the homeostatic model of intake control and within the framework of food conditioning. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of narrowly tuned taste cell populations in lobster (Homarus americanus) feeding behavior.

Developed a whole-animal behavioral assay to measure responses to chemical stimulation of the walking leg (taste) receptors of lobsters. Lesions of only the taste receptors abolished the dactyl clasping response, a result demonstrating that such receptors are necessary to elicit this response. Then the stimulatory effectiveness of natural and synthetic mixtures was determined, particularly of 6 single compounds (glutamate, glutamine, NH?Cl, betaine, aspartate, and taurine) for which the legs have prominent, narrowly tuned receptor cell populations. The results show that a synthetic mixture of the 22 principal amino acids and amines present in mussel tissue was as powerful a stimulus as either a homogenate of such tissue or its purified extract. Of the single compounds, only NH?Cl was stimulatory at the behavioral level. It is unlikely that mixture suppression alone is responsible for the poor behavioral responses to single compounds such as glutamate and to the partial mixtures that were tested. Full response to the more complex mixture of 22 compounds demonstrates that special mixture combinations can override mixture suppression. It is suggested that such signal mixtures may represent the lobster leg's picture of food. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ingestion of a novel flavor before exposure to pups injected with lithium chloride produces a taste aversion in mother rats (Rattus norvegicus).

A series of experiments investigated the ability of Sprague-Dawley mother rats to learn aversions to novel flavors ingested prior to the illness of their pups. In Exp I, 24 mothers learned to avoid a novel flavored solution ingested prior to the illness of their nursing litters. Exp II was designed to investigate the extent to which any adult rat is capable of such learning: 16 nonlactating multiparous females learned aversions to novel flavors ingested prior to exposure to pups injected with LiCl, whereas 16 nonlactating nulliparous females and 16 males did not learn these aversions. Several possible reasons for differences in this learning ability are discussed. In Exps III and IV, the nature of the UCS for these aversions was investigated. Visual, auditory, and taste cues associated with the lithium-injected pups did not mediate the aversions. Evidence suggests that olfactory characteristics of the lithium-injected pups mediated the flavor aversions in the present experiments. These olfactory cues did not appear to be general stress signals but instead were likely specific cues for gastrointestinal discomfort. Results are discussed in terms of classical conditioning and also of their adaptive significance for both mother and offspring. (63 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amphetamine and morphine produce a conditioned taste and place preference in the house musk shrew (Suncus murinus).

Rats have been shown to avoid consuming a flavor, but prefer a location, previously paired with amphetamine or morphine. A series of 4 experiments evaluated the hedonic properties of amphetamine and morphine in the house musk shrew (Suncus murinus), an insectivore that (unlike rats) is capable of vomiting when exposed to toxins. Unlike rats, amphetamine (20 mg/kg) and morphine (20 mg/kg) produced both a conditioned sucrose (0.3 M) and saccharin (0.1%) preference in shrews (administered intraperitoneally), when measured by both a 1-and a 2-bottle test. At the same dose, both drugs also produced a place preference in shrews. These results suggest that the potential of rewarding drugs to produce taste avoidance may vary on the basis of the ability of the species to vomit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of lateralized components of feeding behavior in the ring-tailed lemur (Lemur catta).

Twenty-one ring-tailed lemurs (Lemur catta) were videotaped during feeding. They had previously been classified as left-, right- or ambipreferent on the basis of the hand used to reach for food. The feeding sequences provided duration-based measures of manipulation, hand and mouth lateralization, and posture during feeding sequences with 2 types of food. Hand preference for reaching and holding was stable over time and across measurement conditions. As a group, the lemurs grasped fruit bimanually more often than chow; however, right- and ambipreferent lemurs spent more time holding food bimanually than did left-preferent ones. Older animals consumed chow more quickly than did younger animals but did not differ in their rate of manipulation. Lemurs had a preference for using one side of the mouth in feeding, but this had no directional relation to preferred hand. Three postural feeding patterns were identified. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social influences on feeding site selection by Burmese fowl (Gallus gallus).

Naive, adolescent Burmese red jungle fowl (Gallus gallus spadiceus) observed trained conspecifics feeding in a large enclosure. When tested 48 hrs later, observers exhibited significantly enhanced preferences both for the type of foraging site and for the area in the enclosure where they had observed conspecifics foraging successfully. Such delayed influences of observations of foraging success on the orientation of feeding by an observer can be explained as an instance of stimulus enhancement (K. W. Spence, 1937) but not as an example of local enhancement (W. H. Thorpe, 1963). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning to outwit a competitor in mangabeys (Cercocebus torquatus torquatus).

To investigate whether monkeys would be able to acquire the location of hidden food from the experimenter and later from an informed conspecific, a group of 7 mangabeys (Cercocebus torquatus torquatus) was tested in an experimental design comparable to E. W. Menzel's (1974) with chimpanzees. Food was hidden in the presence of particular animals. An informed young male repeatedly lost his food to a dominant male. Accordingly, the young male developed a pattern, when he alone was informed, of moving in an indirect route to the goal, which generally functioned to mislead the dominant male to the young male's advantage. When the dominant male was also informed, the young male observed the dominant male taking the food or headed straight to the remaining hidden goal. His taking an indirect route, when he alone was informed, cannot therefore be considered his expected response to a competitive situation but rather is a case of tactical deception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand preferences in unimanual and bimanual feeding by wild vervet monkeys (Cercopithecus aethiops).

Lateral preference was examined in spontaneous feeding actions in 2 troops of wild vervet monkeys (Cercopithecus aethiops). Processing of 4 foods (termites, leaf shoots, sugarcane, and fruit) was studied. Actions included unimanual reaching to moving objects, operating from an unstable posture, and coordinated bimanual processing. Between 19 and 31 subjects were available, according to the task. In 2 tasks, laterality of 2 independent stages was measured separately, giving 6 measures in all. On 4 of these measures, most monkeys were ambipreferent, and only a few showed significant hand preferences. Only for termite feeding and detaching material from fruits did the majority show significant lateralization; no tasks elicited exclusive use of 1 hand. Preference appeared labile, because in 2 tasks, population trends reversed with increasing age. No population trends to left or right were found; instead, these monkeys showed ambilaterality, with lateralization associated with task complexity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Numerical competence in a chimpanzee (Pan troglodytes).

A chimpanzee (Pan troglodytes), trained to count foods and objects by using Arabic numbers, demonstrated the ability to sum arrays of 0–4 food items placed in 2 of 3 possible sites. To address representational use of numbers, we next baited sites with Arabic numbers as stimuli. In both cases performance was significantly above chance from the first sessions, which suggests that without explicit training in combining arrays, the animal was able to select the correct arithmetic sum for arrays of foods or Arabic numbers under novel test conditions. These findings demonstrate that counting strategies and the representational use of numbers lie within the cognitive domain of the chimpanzee and compare favorably with the spontaneous use of addition algorithms demonstrated in preschool children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralized changes in tympanic membrane temperature in relation to different cognitive tasks in chimpanzees (Pan troglodytes).

Lateralized changes in tympanic membrane (TM) temperature were assessed in chimpanzees. Subjects were engaged in 1 of 3 different cognitive tasks, including matching-to-sample, visual-spatial discrimination, and a motor task. During execution of each task, TM temperatures were taken from each ear over a 20-min time period. The TM temperatures at each time interval were subtracted from a baseline measure to assess relative change in blood flow. For the matching-to-sample and visual-spatial discrimination tasks, significant lateralized changes in TM temperature were found, with left-ear temperature increasing and right-ear temperature decreasing. No laterality effects were found for the motor or control tasks. These data provide the first evidence of laterality in physiological functioning in chimpanzees and suggest that transient asymmetries in cognitive functions are associated with changes in cerebral blood flow as assessed by TM temperature change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant-mother recognition in a social rodent (octodon degus).

Octodon degus (degu), a biparental species with precocious offspring is a potential model for the study of social attachment and related affective disorders such as depression. This study investigates the nature of the social bond between young degus and their mothers with a special emphasis on infant-mother recognition. We tested young degus in a potentiation paradigm to determine if social contact, particularly with the mother, can modulate an infant's vocal response to isolation. One week later, animals were presented with a choice between their mother and an unfamiliar female or a sample of familiar and unfamiliar nesting materials. Subsequently, the ability of whole litters to discriminate between their mother and unfamiliar females was tested. We observed that infant degus alter their isolation response after brief social contact. Degu infants readily distinguish between familiar and unfamiliar nesting materials but fail to differentiate between their mother and unfamiliar females in an identical setting. Nevertheless, entire litters show a preference for their mothers when tested similarly in a group, demonstrating a perhaps socially facilitated ability to recognize the biological mother at an early age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hearing in a megachiropteran fruit bat (Rousettus aegyptiacus).

The Egyptian fruit bat (Rousettus aegyptiacus) is one of the few megachiropteran bats capable of echolocation. However, it uses rudimentary tongue clicks rather than laryngeally produced echo calls. We determined the audiogram of 2 bats using a conditioned avoidance procedure with fruit puree reward. At an intensity of 60 dB sound pressure level, the bats' hearing extended from 2.25 kHz to 64 kHz, with a region of good sensitivity between 8 kHz and 45 kHz. A dip in sensitivity at 32 kHz appears to be due to pinna directionality. The hearing of Egyptian fruit bats is typical for a mammal of that size and is not as limited as previously reported. Methodological issues, specifically training an animal to listen for low-intensity signals and imposing a significant cost for failing to report signals (i.e., misses), are discussed as the basis for the discrepancy between our results and earlier reports. (PsycINFO Database Record (c) 2010 APA, all rights reserved)