Conditioned suppression of distress calls in imprinted ducklings.

Exposed 20 Peking and 6 Khaki Campbell newly hatched ducklings to imprinting procedures. The subsequent filial reactions were studied using a classical conditioning paradigm. Exp. I revealed that a previously neutral stimulus can become a conditioned suppressor of distress calling as a consequence of pairing it with the imprinted stimulus. If the presentation of the imprinted stimulus was, however, omitted or delayed, or if it preceded rather than followed the presentation of the neutral stimulus, the effect was not obtained. Exp. II utilized a differential conditioning procedure to investigate the capacity of imprinted Ss to come under discriminative control. 2 differently colored lights were used as stimuli; 1 was consistently followed by presentation of the imprinted stimulus, while the other was never followed by its presentation. Only the former stimulus came to suppress distress calling. The importance of the apparent interaction between classical conditioning and imprinting is noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2nd-trimester maternal serum marker results are not altered by delayed analysis

OBJECTIVE: The goal of the study was to evaluate the significance of delayed laboratory analysis of maternal serum alpha-fetoprotein, beta-subunit of human chorionic gonadotropin, and unconjugated estriol for prenatal screening. METHODS: Biochemical analysis of 30 consecutive biochemical screening specimens of maternal serum alpha-fetoprotein, beta-subunit of human chorionic gonadotropin, and unconjugated estriol was performed immediately upon arrival to the laboratory, 7 days later, and again 14 days after maternal blood was drawn. Differences among the results of the three sets of biochemical studies were evaluated by one-way analysis of variance for repeated measures. RESULTS: No significant differences were found among the results of immediate assays as compared with those at a 7- or a 14-day delay for all three biochemical markers. CONCLUSIONS: Our data suggest that up to a 14-day delay in the performance of the 2nd-trimester maternal serum biochemical screening assays will not alter the results significantly. The results of maternal serum screening are, thus, clinically valid even if the laboratory assays were performed several days after maternal blood was drawn.     

Visual depth preferences of the domestic duckling.

Intensively investigated the domestic duckling's depth perception because of its unusual way of life as both a bird and an aquatic animal. Depth perception on the visual cliff, threshold depth, and sensitivity to a wide variety of waterlike conditions were investigated in 486 Giant White Pekin ducklings. While depth perception on the visual cliff was adequate, the Ss plunged off 6-ft heights without hesitation. Overall, monocular depth perception was somewhat inferior to binocular depth perception. Ss had no special sensitivity to waterlike substances. In general, Ss were careless in the presence of depth situations, too careless to survive in other than a flat or watery environment. It is suggested that a possible flocking factor found when Ss were run in pairs may help offset this. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social interaction with siblings is necessary for visual imprinting of species-specific maternal preferences in ducklings (Anas platyrhynchos).

In 4 experiments, 153 24 hr old ducklings were allowed to follow a stuffed mallard hen for 30 min. This experience resulted in a visual preference for the familiar mallard hen over an unfamiliar stuffed redhead (Aythya americana) hen in simultaneous choice tests at 48 and 72 hrs only if the Ss were reared in conditions allowing unrestricted social interaction with siblings, as would normally occur in nature. No visual preference for the familiar mallard model was found at 48 or 72 hrs if Ss were (a) reared in social isolation but allowed to see another duckling, (b) reared with 1 duckling, or (c) reared in a group of ducklings but denied the opportunity for direct social interaction. Results demonstrate the importance of normal social experience in the development of the visual imprinting of filial behavior in ducklings. Imprinting studies have traditionally employed isolation rearing and ignored the precocial bird's natural social context. Thus, the present findings question the appropriateness of the usual methods of studying imprinting in the laboratory for an understanding of the process of filial imprinting in nature. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alarm call responsivity of mallard ducklings (Anas platyrhynchos): IV. Effects of social experience.

In previous experiments on alarm call responsivity, mallard ducklings have been reared in a partially isolated condition in individual boxes that facilitate individual identification. The present study was designed to determine whether a more natural social rearing condition affects freezing behavior. In 3 experiments with mallard ducklings, rearing Ss socially in a 12-bird brood without a hen resulted in a significant reduction in alarm call responsivity. It is suggested that this reduction was caused by a decrease in the level of vocalizations uttered by socially reared Ss. Stimulating socially reared Ss with distress notes, contentment notes, or pre-exodus assembly calls reinstated high levels of freezing. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constitutional biases in early perceptual learning: II. Visual preferences in artificially selected, visually naive and imprinted quail chicks (C. coturnix japonica).

Tested approach choices in genetically and environmentally manipulated quail chicks with pairs of stimuli identical in size and luminance but different in color, flicker, or both color and flicker. Data indicated comparable flicker and vastly different color preferences in Ss that were bidirectionally selected for color choices. In the choices between composite stimuli, flicker effects dominated over color effects in genetic controls, and color effects over flicker effects in selected Ss. Imprinting to colors modified color preferences, but imprinting to white or colored flicker did not change, or only marginally changed, flicker preferences. Flicker in testing stimuli, however, influenced the phenotypic expression of acquired color preferences. Implications concerning the nature of constitutional biases and constitution–environment interactions in early perception and perceptual learning are discussed. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intracerebroventricular ethanol-induced conditioned place preferences are prevented by fluphenazine infusions into the nucleus accumbens of rats.

The rewarding properties of centrally administered ethanol (EtOH) were examined using a conditioned place preference (CPP) test. Male rats subjected to bilateral intracerebroventricular (icv) infusions of EtOH (0-240 nmol) produced a dose-dependent preference for the drug-paired environment that was potentiated by concurrent intravenous (iv) administration of heroin (0.025 mg/kg). The role of mesolimbic dopamine (DA) pathways in the development of EtOH reward was then examined by challenging EtOH-treated rats with bilateral intra-accumbens shell applications of a DA receptor antagonist. Fluphenazine (10 or 50 μg/side), infused immediately prior to daily place conditioning trials, was found to reliably attenuate the development of CPPs produced by icv EtOH administration. When fluphenazine was administered into the nucleus accumbens shell prior to the final test trial only (i.e., in already conditioned rats), intra-accumbens shell DA receptor blockade was found to prevent the expression of CPPs produced by icv EtOH. In summary, rats form reliable learned preferences for EtOH-paired locations (CPPs) that are potentiated by iv heroin and whose acquisition and expression rely on intact DA functionality within the nucleus accumbens. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alarm call responsivity of mallard ducklings (Anas platyrhynchos): VI. Effects of sibling and self-produced auditory stimulation.

Mallard ducklings (Anas platyrhynchos) respond without obvious training to the species-typical maternal alarm call by ceasing all vocal and locomotor behavior (i.e., freezing). Previous experiments have demonstrated that 1-day-old ducklings must be exposed perinatally to normally occurring duckling vocalizations. Yet, these experiments did not determine whether the source of vocalizations is important. The present experiments attempt to assess the importance of two different sources of normally occurring stimulation: sib and self-stimulation. Preventing ducklings from hearing the vocalizations of sibs reduces alarm call responsivity. Eliminating the duckling's own self-produced vocalizations, in addition to auditory isolation, further attenuates responsiveness. Finally, sib stimulation alone fully reinstates responsiveness. These data indicate that both social and self-stimulation play important roles in the development of alarm call responsivity. In addition, our results suggest that some species-typical behaviors may be affected by a variety of experiences rather than a particular aspect or source of experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal place fields are altered by the removal of single visual cues in a distance-dependent manner.

Hippocampal CA3 cells were recorded in male Long-Evans rats that explored a square recording chamber. Three of the 4 chamber walls held a rectangular cue card, each of different size. Rotating the set of cue cards rotated the location of the place fields. Place fields were common close to the walls of the recording chamber, particularly the walls with cues. When single cues were removed, the spatial information content decreased but returned to baseline levels when the cue was replaced. When a cue near a place field was removed, the place field firing rate and area decreased; when a distant cue was removed, firing rate and area increased. Thus, removing single visual cues predictably and reversibly altered hippocampal place fields. Together, the results suggest that hippocampal neurons may optimize the encoding of visual information and are consistent with a distance-encoding hypothesis of CA3 network function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The reinforcing effects of ethanol are altered by the endogenous neurosteroid, allopregnanolone

We examined the effect of systemic administration of the endogenously occurring progesterone metabolite, allopregnanolone, on oral self-administration of ethanol by male rats. Rats were trained to perform an operant response for presentation of 0.1 ml of a solution of 10% ethanol in water using the sucrose fading technique. After acquisition of stable lever-press responding on a fixed-ratio 4 schedule, subjects received subcutaneous injections of 1, 3, or 10 mg/kg of allopregnanolone, or vehicle, 20 min prior to the self-administration session. Pretreatment with 3 mg/kg, but not 1 or 10 mg/kg, increased the mean total number of lever press responses made to obtain ethanol, and therefore increased the mean total number of ethanol presentations. The number of responses and response rate were examined as a function of the number of "runs" within the 30-min session; a "run" was defined as a series of consecutive responses with an interresponse interval of <1 min. The increase in total responses after 3 mg/kg was due in part to an increased number of responses for the first run of the session, with no effect on response rates. However, the higher dose of 10 mg/kg decreased response rates within the first run. Thus, allopregnanolone alters ethanol-reinforced responding at concentrations lower than those that depress rates of responding. The effects of administration of the benzodiazepene, diazepam, were determined for comparison with those of the neurosteroid. The subcutaneous injection of 0.3, 1.0, or 3.0 mg/kg of diazepam did not produce any clear dose-dependent changes in measures of ethanol-reinforced operant responding, supporting the suggestion of differences in the contribution of the benzodiazepene and neurosteroid binding sites to GABA(A) receptor function. The results indicate that exogenous administration of allopregnanolone dose-dependently alters ethanol-reinforced operant responding, and suggest that this endogenously occurring neurosteroid could mediate some of the reinforcing effects of ethanol.     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Values and preferences are not necessarily the same

Economic theory typically draws no distinction between preferences and values, assumes that preferences are stable and complete and that all that need be done to elicit them is to ask the right question in the right way. It is argued here that values for some fundamental aspects of life, such as health, are not the same as preferences. The former are less differentiated and require construction and clarification before they can be elicited. The implications of this for health state valuation are discussed.     

Enzymes of the gamma-glutamyl cycle are programmed in utero by maternal nutrition

Regenerative axon growth in peripheral neurons is accompanied by increased expression of the growth-associated protein GAP-43. We examined the increase of GAP-43 immunoreactivity in DRG neurons following lesions at different distances along the sciatic nerve, using immunocytochemistry. To control for the variable involvement of DRG axons following injury at different sites, injured neurons were identified by retrograde labeling with Fluoro-Gold. GAP-43 labeling was similar for proximal, distal, and far-distal injuries when only injured neurons are considered. Our results stand in contrast to studies which show that GAP-43 upregulation in neurons of the central nervous system occurs only when lesions are made close to the cell body. This suggests that the mechanisms which control GAP-43 expression following injury differ between central and peripheral neurons.     

Early events in the development of neuronal polarity in vitro are altered by ethanol

Among the neuropathological effects of prenatal exposure to ethanol is the disruption of neuromorphogenesis. The effects of ethanol on early events in the development of axons and dendrites were studied using cultured embryonic rat hippocampal neurons, which develop in vitro in a stereotypical sequence of events that mimics their development in vivo. During the first 24 hr in culture, hippocampal neurons attach to the substrate and develop into one of three stages identified by phase-contrast microscopy: (i) neurons having lamellipodia and no processes (stage 1); (ii) neurons developing minor processes (<40 microm) that subsequently become the cell's axon or dendrites (stage 2); or (iii) polarized neurons with at least one axon (process with length > or =40 microm) (stage 3). Exposure to ethanol (300 mg/dl or 800 mg/dl) in the culture medium resulted in an increase in both the number of minor processes per neuron and the number of stage 3 neurons having more than the typical single axon. In addition, ethanol exposure significantly altered the proportion of neurons in the three early stages of development at 18 to 24 hr in vitro, without affecting overall neuron survival. With ethanol, there was a smaller proportion of neurons in the first stage of development, and a greater proportion of polarized stage 3 neurons. These findings suggest that ethanol alters the normal establishment of neuronal polarity, disrupting mechanisms that ensure the formation of the appropriate number of processes and that regulate the timing of process outgrowth.     

Cleavage planes in frog eggs are altered by strong magnetic fields

Early cleavages of Xenopus embryos were oriented in strong, static magnetic fields. Third-cleavage planes, normally horizontal, were seen to orient to a vertical plane parallel with a vertical magnetic field. Second cleavages, normally vertical, could also be oriented by applying a horizontal magnetic field. We argue that these changes in cleavage-furrow geometries result from changes in the orientation of the mitotic apparatus. We hypothesize that the magnetic field acts directly on the microtubules of the mitotic apparatus. Considerations of the length of the astral microtubules, their diamagnetic anisotropy, and flexural rigidity predict the required field strength for an effect that agrees with the data. This observation provides a clear example of a static magnetic-field effect on a fundamental cellular process, cell division.     

Development of species identification in ducklings: VII. Highly specific early experience fosters species-specific perception in wood ducklings.

Wood ducklings find the maternal assembly call of their species attractive in advance of exposure to it. A critical acoustic feature of the maternal call is the descending frequency modulation (FM) of its notes. The ducklings' vocalizations themselves have a pronounced descending FM, albeit in a much higher frequency range than the maternal call. Four experiments tested the possibility that the maternally naive duckling's sensitivity to the descending FM of the maternal call notes might derive from prior exposure to its own vocalizations. 184 wood duck embryos were placed in individual auditory isolation several days before hatching and tested for their preference for the descending FM in choice tests with ascending and descending synthetic maternal calls after hatching. Results indicate the wood ducklings' usual preference for the descending frequency modulation in the maternal call of its species is a function of prior exposure to specific properties of their own vocalizations in the normal course of events. Since the fit between the relevant acoustic feature of the ducklings' vocalizations and the critical perceptual feature of the maternal call is an abstract one, the present finding is an example of a nonobvious experiential precursor to behavior that otherwise would seem to be "innate" or "instinctive." (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of proteins whose amounts are altered by mutation in the pgsA gene of Escherichia coli

We identified proteins whose amounts were altered in an Escherichia coli pgsA3 mutant lacking the potential to synthesize phosphatidylglycerolphosphate, a precursor of phosphatidylglycerol. Proteins whose amounts were increased in the mutant were protease Do, periplasmic oligopeptide-binding protein, tryptophanase, and an unidentified protein, while the decreased one was flagellin. Transformation of the mutant with a plasmid containing the wild type pgsA gene complemented the phenotype, indicating that the pgsA3 mutation is responsible for the phenotype.     

Visual masking by homonyms.

Words masked by their own homophones are more disrupted than words masked by unrelated control words. Conversely, words masked by their own associates are less disrupted than unrelated control words. This indicates that the association effect in masking cannot be due to response bias. A model to account for these results is proposed and was tested on 15 undergraduates. Results suggest that the facilitatory effect of masking by associates occurs in the perception of the target word, but the inhibitory effect of masking by homophones occurs in the attempted response or vocalization of the target words by the Ss. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual evoked potentials are affected by trunk rotation in neglect patients

Steady-state visual evoked potentials (VEPs) were recorded in four patients with unilateral visuo-spatial neglect, stimulating either the left or the right hemifield. In the standard condition (head and body oriented straight ahead towards the stimulus) the left hemifield VEP was delayed. When the body was turned to the left, however, the two hemifield latencies were comparable. These results were confirmed with the transient VEP technique. No effect of trunk rotation was observed in a group of patients with left brain damage and without neglect. The results imply that the sensory afferents from neck muscles might restore the altered occipital activity and suggest that the same conditions which modulate neglect modulate VEPs latencies.     

Priming of ducklings' responses by presenting an imprinted stimulus.

Conducted 7 experiments to determine whether brief presentation of an imprinted stimulus might cause behavioral aftereffects of the sort that characterize positively reinforcing brain stimulation, i.e., enhanced responding following an E-administered stimulus presentation (i.e., a prime). After ducklings were trained to peck a pole for presentations of a moving imprinted stimulus, primes by that stimulus enhanced subsequent pecking over a base-line rate. This enhancement effect increased as prime duration lengthened and appeared absent when the stimulus remained stationary during the priming presentation. In other experiments in which ducklings were not pole-peck trained, primes enhanced subsequent emission of distress vocalization. As with pole pecks, distress call enhancement increased with longer primes and was absent after primes by the stationary stimulus. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)