Auditory basis of maternal attachment in ducklings (Anas platyrhynchos) under simulated naturalistic imprinting conditions

The presence of broodmates during the imprinting process results in peer imprinting that interrupts a visually mediated maternal attachment. We sought to determine the conditions in which group-trained mallard ducklings (Anas platyrhynchos) acquire a maternal attachment. At 48 hr of age, ducklings were allowed to follow a vocal, stuffed mallard hen individually or in groups of 4. Individual ducklings showed a preference for the silent, familiar mallard over an unfamiliar pintail. Ducklings trained in groups did not show a preference. When the mallard maternal call was present during testing, group-trained ducklings overwhelmingly responded to it regardless of whether it came from the familiar mallard or an unfamiliar pintail. Training ducklings in groups, which simulates the natural social context of imprinting, results in peer imprinting. Thus, early in development the young become visually imprinted to each other, and the maternal call mediates attachment to the mother.     

Comparison of scotopic sensitivity in diurnal (Anas platyrhynchos) and crepuscular (Dendrocygna autumnalis) ducks.

Scotopic visual adaptation curves were obtained from 4 mallard ducks. A curve of best fit was used to compare the mallards' mean adaptation curve to the curve previously reported for the black-bellied tree duck, a crepuscular species. The curves did not differ significantly in either their slopes or base levels (thresholds). The mallards curve had a rod-cone "break" at approximately 25 min. This break is evident in the scotopic curve for pigeons, but is absent from the black-bellied tree ducks' curve. Examination of retinal tissues indicated that the black-bellied tree ducks had significantly more rods and cones, and a larger rod:cone ratio than the mallards. The mallards' scotopic visual threshold is exceeded by the natural illumination present under several nocturnal conditions.     

Species-specific auditory preference of bobwhite quail chicks (Colinus virginianus) is altered by social interaction with siblings

This study examined whether reinstating specific aspects of the normally occurring postnatal setting (ongoing social interaction with siblings during rearing and/or testing) would influence bobwhite quail chicks' attraction to their species-typical maternal call. Results revealed that incubator-reared chicks exhibit a strong preference for the species-typical bobwhite maternal call over a group of same-aged siblings in simultaneous choice tests at 24 hr and 48 hr after hatching, but only if the birds are kept in relative social isolation. No preference for the maternal call was found at 24 hr or at 48 hr if chicks were reared in a group of same-aged chicks from hatching and tested to the maternal call vs. siblings or the maternal call paired with a live adult bobwhite hen vs. siblings. These results raise doubts about the appropriateness of the usual methods of isolation rearing in the study of species-typical perceptual preferences and underscore the importance of considering features of the natural social context in the analysis of early perceptual and social behavior.     

Naturalistic psychophysics: thresholds of ducklings (Anas platyrynchos) and chicks (Gallus gallus) to tones that resemble mallard calls

Neonatal ducklings and chickens were tested for responsiveness to a pulsing pure tone that was as similar as possible to the mallard maternal alarm call. It is known that ducklings momentarily cease vocalizing when they hear the alarm call and that chicks do the same when they hear pure tones. The duration of peep suppression can thus be used as a measure of whether subjects of either species heard the stimulus. Chicks might not be as sensitive as ducklings to a mallard alarm call because the signal is less significant to them. An adaptive or staircase procedure was used to estimate absolute thresholds, and group psychometric functions were reconstructed for each species from the trial-by-trial data. Ducklings had lower thresholds than chickens as well as steeper psychometric functions to this stimulus. The results suggest that more sensitive and consistent behavioral responses can be elicited by naturalistic sounds than by more arbitrary acoustic stimuli.     

Baboon (Papio hamadryas) visual preferences for regions of the face

Preferences for regions of the face were examined in four members of a hamadryas baboon (Papio hamadryas) group. Subjects were presented a series of photographic slides displaying various facial regions and combinations of regions of the dominant male in the group with the use of the method of paired comparison. An apparatus consisting of a two-slide screen/two-push-button arrangement permitted the baboons to control slide selection and viewing duration. Both duration and frequency of slide activation were recorded. Correlations of viewing durations among all subjects were significant (p less than or equal to .05). The eye region alone and in combination with other regions received significantly more attention than did all other regions or combinations. Frequency measures were not significant. The results support findings obtained with rhesus monkeys (Macaca mulatta) and suggest that the eye region may provide a primate with an important source of information, possibly information about intent.     

Tests of preferences of young deer mice (Peromyscus maniculatus bairdi) for siblings versus nonsiblings

Three experiments were conducted to test the performance of young deer mice (Peromyscus maniculatus bairdi) in associating preferentially with siblings versus nonsiblings. In Experiment 1, neither males nor females preferred caged siblings versus nonsiblings. In Experiment 2, with full contact permitted, nonsibling males were in contact as much as were sibling males. In Experiment 3, with pairs of littermate pairs permitted full contact, there was no significant differential association. Although discrimination and preferences related to kinship have been demonstrated in some species, they cannot be assumed to be universal.     

Muscarinic transmission in the basolateral amygdala is necessary for the acquisition of socially transmitted food preferences in rats

We examined the involvement of muscarinic receptors in the basolateral amygdala (BLA) in the social transmission of food preference (STFP) learning by assessing the effects of scopolamine (20 microg/side), injected prior to social training, on a 24-h food-choice test. Muscarinic receptor blockade in the BLA significantly impaired STFP, as shown by the rats' chance preference for the odorized trained food. The present results are consistent with the suggestion that intact cholinergic transmission in the BLA is necessary for acquisition and/or initial consolidation and provide evidence that BLA integrity is part of the underlying circuit of STFP learning.     

Enhanced prenatal auditory experience facilitates species-specific visual responsiveness in bobwhite quail chicks (Colinus virginianus)

Premature stimulation of a later developing sensory system is known to impact the functioning of earlier developing sensory systems. For example, exposure to premature (prenatal) visual experience results in a decline in species-typical auditory responsiveness in several precocial bird species. The present study examined the influence of experiential enhancement of an earlier developing sensory system on a later developing modality. Specifically, the influence of enhanced prenatal auditory stimulation on subsequent postnatal auditory and visual functioning of bobwhite quail (Colinus virginianus) chicks was assessed. Results indicate that birds receiving exposure to increased amounts of unaltered, species-typical embryonic vocalizations before hatching show species-typical auditory responsiveness at both 12 hr and 24 hr after hatching, but exhibit an accelerated pattern of species-typical visual responsiveness by 24 hr of age. These findings suggest that enhancement of an earlier developing sensory system can facilitate the development of a later developing sensory system and serve to demonstrate the dynamic nature of early perceptual organization.     

Ventral lateral geniculate input to the medial pons is necessary for visual eyeblink conditioning in rats

The conditioned stimulus (CS) pathway that is necessary for visual delay eyeblink conditioning was investigated in the current study. Rats were initially given eyeblink conditioning with stimulation of the ventral nucleus of the lateral geniculate (LGNv) as the CS followed by conditioning with light and tone CSs in separate training phases. Muscimol was infused into the medial pontine nuclei (MPN) after each training phase to examine conditioned response (CR) retention to each CS. The spread of muscimol infusions targeting the MPN was examined with fluorescent muscimol. Muscimol infusions into the MPN resulted in a severe impairment in retention of CRs with the LGNv stimulation and light CSs. A less severe impairment was observed with the tone CS. The results suggest that CS information from the LGNv and light CSs is relayed to the cerebellum through the MPN. Retrograde tracing with fluoro-gold (FG) showed that the LGNv and nucleus of the optic tract have ipsilateral projections to the MPN. Unilateral inputs to the MPN from the LGNv and nucleus of the optic tract may be part of the visual CS pathway that is necessary for visual eyeblink conditioning.The neural substrates of associative motor learning have been studied extensively using eyeblink conditioning (Christian and Thompson 2003; Thompson 2005). Eyeblink conditioning is typically established by pairing a tone or light conditioned stimulus (CS) with an unconditioned stimulus (US) that elicits the eyeblink reflex. An eyeblink conditioned response (CR) emerges over the course of paired training, and the peak of eyelid closure occurs at the onset time of the US. Results from experiments using temporary lesions of the cerebellar deep nuclei or cerebellar cortex indicate that the anterior interpositus nucleus and cerebellar cortex are necessary for acquisition, expression, and extinction of eyeblink conditioning (Krupa et al. 1993; Hardiman et al. 1996; Krupa and Thompson 1997; Garcia and Mauk 1998; Medina et al. 2001; Bao et al. 2002; Freeman et al. 2005a). Blocking cerebellar output with inactivation of the superior cerebellar peduncle, red nucleus, or brainstem motor nuclei selectively blocks CR expression but not acquisition, providing further evidence that learning occurs in the cerebellum (Chapman et al. 1990; Krupa et al. 1993, 1996; Krupa and Thompson 1995).Sensory stimuli from every modality are sent to the pontine nuclei (PN), which receive projections from the lower brainstem, thalamus, and cerebral cortex (Glickstein et al. 1980; Brodal 1981; Mihailoff et al. 1989; Schmahmann and Pandya 1989; Wells et al. 1989; Knowlton et al. 1993; Campolattaro et al. 2007). Neurons in the PN project CS information to the cerebellum via mossy fibers in the middle cerebellar peduncle that synapse on granule cells in the cerebellar cortex and on neurons in the interpositus nucleus (Bloedel and Courville 1981; Brodal 1981; Steinmetz and Sengelaub 1992; Mihailoff 1993). Lesions of the middle cerebellar peduncle impair eyeblink conditioning with auditory, somatosensory, and visual CSs (Lewis et al. 1987). Bilateral electrolytic lesions of the dorsolateral and lateral pontine nuclei (LPN) block retention of CRs to an auditory CS but have no effect on light-elicited CRs (Steinmetz et al. 1987). Inactivation of the contralateral LPN blocks CRs to a tone CS but not to lateral reticular nucleus stimulation in rabbits (Bao et al. 2000). Moreover, stimulation of the LPN or middle cerebellar peduncle is a sufficient CS for eyeblink conditioning (Steinmetz et al. 1986, 1987; Tracy et al. 1998; Bao et al. 2000; Freeman and Rabinak 2004; Freeman et al. 2005b; Campolattaro and Freeman 2008). The findings from the lesion, inactivation, and stimulation studies provide evidence that the PN is the proximal part of the CS pathway for cerebellar learning. These studies also indicate that the LPN is the primary source of auditory CS input to the cerebellum.Only a few studies have examined the visual CS pathway necessary for eyeblink conditioning. The dorsal and ventral divisions of the lateral geniculate nucleus of the thalamus (LGNd, LGNv), pretectal nuclei, visual cortex (VCTX), and superior colliculus (SC) comprise a hypothesized parallel visual CS pathway for eyeblink conditioning (Koutalidis et al. 1988). Combined lesions of all of these visual areas completely block acquisition, lesions of two visual areas produce a partial impairment, and lesions in one visual area do not impair CR acquisition (Koutalidis et al. 1988). Stimulation of the VCTX, SC, and LGNv support eyeblink conditioning, and each of these structures has a direct unilateral projection to the PN that could be important for eyeblink conditioning (Halverson et al. 2009). The lesion and stimulation studies provide evidence that structures in the hypothesized visual CS pathway are independently capable of supporting conditioning. An important aspect of the visual CS pathway proposed in the Koutalidis et al. (1988) study is distributed projections of each visual area to different regions of the PN. The important projections were hypothesized to be from the VCTX to the rostral portion of the PN, from both the SC and pretectal nuclei to the dorsolateral PN, and the LGNv projection to the medial pontine nuclei (MPN) (Koutalidis et al. 1988). Lesions of the VCTX were substituted for LGN lesions in the Koutalidis et al. (1988) study due to technical problems with animal survival. The LGNv projection to the MPN was therefore not examined in their combined lesion group. Stimulation of the anterior pretectal nucleus is not a sufficient CS to support eyeblink conditioning (Campolattaro et al. 2007). The direct PN projection from the VCTX is not necessary for CR retention to a light CS, as lesions do not prevent eyeblink conditioning to a light CS in dogs or monkeys (Hilgard and Marquis 1935, 1936). Moreover, lesions of the entire cerebral cortex do not prevent acquisition or retention of delay eyeblink conditioning to a tone or light CS in rabbits (Oakley and Russell 1972, 1977). The LGNv and SC, therefore, are likely sources of visual input to the PN that is necessary for eyeblink conditioning.The current experiment investigated whether information from the LGNv and a visual CS (light) share similar inputs into the MPN and whether those inputs are different from an auditory CS. The visual projections to the MPN were also investigated with the retrograde tracer fluoro-gold (FG) to identify structures that may be involved with the relay of CS information during eyeblink conditioning. In the conditioning experiment, rats received three phases of training, with each phase consisting of three acquisition sessions followed by a muscimol infusion into the MPN, and then a saline recovery session. Each rat received unilateral stimulation of the LGNv (contralateral to the trained eye) during phase 1 of training followed by either a tone or light CS in phases 2 and 3 (order of stimulus presentation was counterbalanced). One group received LGNv stimulation in phase 1 followed by a light CS in phase 2, and a tone CS in phase 3 (SLT). The other group received the tone CS in phase 2, and light CS in phase 3 (STL).     

Social transmission and memory of food preferences in pine voles (Microtus pinetorum)

The social transmission of food preferences is affected by factors including the length of time a preference is maintained. The authors investigated the social transmission of food preferences in pine voles (Microtus pinetorum) and whether food items had to be present for memory to persist. A demonstrator vole was fed cocoa-flavored food, a nonpreferred food. After interacting with a demonstrator vole, observer voles preferred cocoa-flavored food as compared with either naive voles that had not interacted with demonstrators or voles that had been exposed to odors. Observers retained this preference for 72 hr after interacting with an observer whether or not flavored foods were present. The ability to learn which food items are palatable and safe may benefit a generalist herbivore that has faced selection to avoid toxic baits.     

Amount of prenatal visual stimulation alters incubation times and postnatal preferences in leopard geckos (Eublepharis macularius)

The authors exposed gecko (Eublepharis macularius) embryos to patterned visual stimulation beginning at either 1 week or 2 weeks prior to hatching. Embryos exposed to the substantially augmented amount of prenatal visual stimulation hatched significantly earlier than the embryos either exposed to the moderately augmented prenatal visual stimulation or not exposed to any prenatal visual stimulation (p < .01). Hatchling mass was not affected. Embryos exposed to substantially augmented visual stimulation demonstrated a postnatal preference for patterned light in a simultaneous choice test at 24 hr of age (p < .01). Control embryos demonstrated a preference for normal light conditions (p < .01), whereas experimental embryos exposed to lesser amounts of prenatal visual stimulation did not show a preference for either stimulus. At 1 week of age, geckos in all conditions failed to exhibit a preference for either stimulus.     

Social transmission of flavor preferences in two species of hamsters (Mesocricetus auratus and Phodopus campbelli)

Golden hamsters (Mesocricetus auratus) and dwarf hamsters (Phodopus campbelli) interacted with a conspecific demonstrator that had recently consumed a flavored food. When given a choice between their demonstrator's flavor and another flavor, the dwarf hamsters preferred the flavor their demonstrator had eaten. Golden hamsters did not prefer their demonstrators' diets when the demonstrators were unrelated adults or littermates, but they did when the demonstrator was their mother. Videotaping the interactions between demonstrators and observers revealed that adult golden hamsters did not investigate foods hoarded by their demonstrators whereas dwarf hamsters did. These results are interpreted in terms of the stimuli that activate feeding behavior systems in these 2 hamster species.     

Measuring social change preferences in African American adolescents: development of the Measure of Social Change for Adolescents (MOSC-A)

Studies addressing Black adolescents' social change strategies are nonexistent and might be associated with the absence of social change measures for Black adolescents. In an effort to begin addressing this concern, the 30-item Measure of Social Change for Adolescents (MOSC-A) was designed to measure Black adolescents' first- (i.e., within the system) and second- (outside of the system) order social change strategies. Factor analysis of responses that 226 Black adolescents gave to the MOSC-A revealed first- and second-order social change factors. Item response theory analyses revealed that 65% of the items on the former factor adequately discriminate across different trait levels, but those of the latter were less promising. Scaffolded on this study, future research might refine the MOSC-A's psychometric properties and improve its utility.     

Social transmission of food preferences in Japanese monkeys (Macaca fuscata) after mere exposure or aversion training

In Experiment 1, 3 mother-child pairs of Japanese monkeys (Macaca fuscata) were given simultaneous choice tests between raisins and popcorn. The mothers and offspring showed different choice patterns. Cofeeding opportunities were then alternated with individual choice tests. In Experiment 2,2 other pairs were added. Each animal was again offered simultaneous choice tests between marshmallows and almonds. Food aversion conditioning was used to create different choice patterns for mothers and offspring. After cofeeding and choice tests, the differences in choice patterns disappeared in both experiments. The changes after contact with the other's eating pattern during cofeeding was as follows: foods consumed by either came to be eaten by both; foods consumed by both continued to be eaten by both; and foods consumed by neither continued to be ignored. The results provide evidence for social transmission of food preferences in this species.