Genetic architecture of olfactory discriminative avoidance conditioning in Drosophila melanogaster

Recent claims to have demonstrated associative learning ability in Drosophila melanogaster raise questions about the adaptive significance of behavioral modifiability of this species. In a strain survey and a 9 X 9 half diallel cross study of olfactory discriminative avoidance conditioning, a low narrow heritability and strong directional dominance or heterosis controlling nonrandom phenotypic variation were found. Furthermore, the predicted inbreeding depression and asymmetrical response to bidirectional genetic selection were both observed. The genetic architecture revealed in these experiments is consistent with a close association between this conditioning phenotype and evolutionary fitness. Predictions from this interpretation to the nature of new mutations have been confirmed, and a possible role for conditioning in courtship behavior has been identified.     

Digital measurement of operant disk press force maintained in CD-1, BALB/c, and C57BL/6 mice

Force of disk press responses by inbred (C57BL/6 and BALB/c) and outbred (CD-1) mice were measured with a PC/DOS-based system, which allowed for continuous measurement of pressing, as well as for control of reinforcer presentation on the basis of response-force dimensions. Photobeam-based measurement of mouse entry into a hopper where reinforcers were presented provided additional information about anticipatory and consumatory behavior in relation to environmental stimuli leading up to reinforcer delivery Disk pressing was generated and measured with the use of an analog-to-digital interface with all three mouse strains. The strains differed in the physical and temporal characteristics of the disk press, as well as in the behavioral chain leading to reinforcer presentation. These measurement methods appear well suited for quantitating functional behavioral differences occasioned by genetic variations in mice.     

Genetic influences on digging behaviors in mice (Mus musculus) in laboratory and seminatural settings

Digging behaviors of several inbred strains of laboratory mice and some of their crosses were examined in three contexts. In laboratory burrow boxes, C57BL/6Abg mice constructed more sophisticated burrow systems than did BALB/cAbg mice. Their F1 hybrids built burrow systems more complex than either parental strain. The same pattern of genetic influence was observed in an outdoor pen. In an escape task that required digging, BALB/c mice escaped more quickly than did C57BL/6 mice; their F1 hybrids showed dominance toward the BALB/c phenotype. These results indicate that behavioral polymorphisms in digging behavior, which may relate to habitat selection, have a genetic basis. The dominance and overdominance toward the better digging parental strain in each type of task suggest the possible evolutionary importance of these digging behaviors.     

Strain-dependent differences in LTP and hippocampus-dependent memory in inbred mice

Many studies have used "reverse" genetics to produce "knock-out" and transgenic mice to explore the roles of various molecules in long-term potentiation (LTP) and spatial memory. The existence of a variety of inbred strains of mice provides an additional way of exploring the genetic bases of learning and memory. We examined behavioral memory and LTP expression in area CA1 of hippocampal slices prepared from four different inbred strains of mice: C57BL/6J, CBA/J, DBA/2J, and 129/SvEms-+(Ter?)/J. We found that LTP induced by four 100-Hz trains of stimulation was robust and long-lasting in C57BL/6J and DBA/2J mice but decayed in CBA/J and 129/SvEms-+(Ter?)/J mice. LTP induced by one 100-Hz train was significantly smaller after 1 hr in the 129/SvEms-+(Ter?)/J mice than in the other three strains. Theta-burst LTP was shorter lasting in CBA/J, DBA/2J, and 129/SvEms-+(Ter?)/J mice than in C57BL/6J mice. We also observed specific memory deficits, among particular mouse strains, in spatial and nonspatial tests of hippocampus-dependent memory. CBA/J mice showed defective learning in the Morris water maze, and both DBA/2J and CBA/J strains displayed deficient long-term memory in contextual and cued fear conditioning tests. Our findings provide strong support for a genetic basis for some forms of synaptic plasticity that are linked to behavioral long-term memory and suggest that genetic background can influence the electrophysiological and behavioral phenotypes observed in genetically modified mice generated for elucidating the molecular bases of learning, memory, and LTP.     

Genetic factors and the measurement of exploratory activity

The progenitor strains C57BL/6 and BALB/c and the seven recombinant inbred strains derived from them were used to examine the genetic relationship between two measures of activity and hippocampal lamination defect (Hld). Fifty-three mice (Mus musculus), 9 from each of the progenitor strains and 5 from each recombinant inbred strain, were tested for 16 min in a device which permitted both unobstructed traverse of the length of a runaway and contact with objects which were aligned alongside the runway. The C57BL/6 mice produced significantly more locomotor (runway traversal) activity, whereas the BALB/c showed significantly greater amounts of investigatory (object contact) activity. This reversal of relative position in the distribution of scores was not present for the recombinant strains. There was no dichotomous separation of recombinant strains for either measure. Examination of activity in terms of four consecutive 4-min periods indicates differences among the strains with respect to changes during the test session. The strains may be dichotomized with respect to decrement in activity within the 16-min session, but these groups do not correspond with those reported by others. The inference of a single genetic determinant for activity measured either as locomotor or investigatory responses is not supported by these data, nor is there any apparent relationship between activity and Hld. The critical influence of genetic-environment interactions in determining behavior and the effect of the selection of measurement techniques upon interpretation of data are emphasized by these data.     

The inheritance of agonistic behavior in male mice: A diallel analysis

The diallel cross genetic design was employed to determine the pattern of inheritance of male-male agonistic behavior in laboratory mice. The results indicated strong strain differences in agonistic behaviors and strain ranks that replicated previous findings. The genetic analysis showed the presence of additive and nondirectional dominance effects on the behaviors measured. This pattern has been characterized as indicating the action of stabilizing selection and indicates that the trait has not been under directional selection.     

Cross‐magnitude interactions across development: Longitudinal evidence for a general magnitude system

There is general agreement that humans represent numerical, spatial, and temporal magnitudes from early in development. However, there is disagreement about whether different magnitudes converge within a general magnitude system and whether this system supports behavioral demonstrations of cross‐magnitude interactions at different developmental time points. Using a longitudinal design, we found a relation between children's cross‐magnitude interactions assessed at two developmental time points with different behavioral measures. More specifically, stronger cross‐magnitude interactions in infancy (M = 9.3 months) predicted a stronger cross‐magnitude congruity effect at preschool age (M = 44.2 months), even when controlling for performance on measures of inhibitory control, analogical reasoning, and verbal competence at preschool age. The results suggest a common mechanism for cross‐magnitude interactions at different points in development as well as stability of the underlying individual differences. We argue that this mechanism reflects a nonverbal general magnitude system that is operational early in life and that displays continuity from infancy to preschool age.     

Evolutionary psychology and consumer behavior: A constructive critique

We examine the theoretical basis for the evolutionary narrative common to the target papers by Saad (this issue) and by Griskevicius and Kenrick (this issue) and identify areas of controversy that have sparked debate about evolutionary psychology [EP] among biologists and behavioral ecologists. The two main areas of disagreement are over (1) the role of genetic adaptations resulting from natural selection in ancient times compared to other forces leading to current behavior; and (2) the likelihood that evolution resulted in a set of highly specialized mental modules or information-processing circuits thought to be instrumental in determining present-day behavior. We review the EP research discussed by the authors of the target papers as a means of evaluating the evidence in support of the theory and of suggesting future directions of research.     

Increasing acquaintanceship and complementarity of behavioral styles and personality traits among college roommates

Robert Carson's principle of complementarity asserts that the behavioral styles of interaction partners tend to complement each other by encouraging individuals to act opposite in terms of dominance and similar in terms of warmth. The principles of complementarity further hypothesize that as relationships progress through multiple interactions, the behavioral styles of its members will be altered to increase complementarity. To examine this acquaintanceship hypothesis, the behavioral styles and personalities of 102 college roommate dyads were assessed after living together for 2 weeks and again after living together for 15 weeks. Consistent with the acquaintanceship hypothesis, after 2 weeks the behavioral styles of roommates did not complement each other; however, after 15 weeks, the behavioral styles of roommates strongly complemented each other. In contrast to the change in complementarity observed in roommates' behavioral styles, participants' perceptions of their own personalities were relatively unaffected by the personalities of their roommates.     

Inbreeding of Wistar-Kyoto rat strain with hyperactivity but without hypertension

A genetic inbreeding program using Wistar-Kyoto rat strains as progenitors was used to combine the hyperactivity trait of the spontaneously hypertensive rat (SHR) with the normotensive trait of the WKY genetic control strain. From an SHR X WKY cross we produced a gene-assorting F2 population from which selected brother-sister matings were carried out through seven successive inbred populations. This program produced a new strain of hyperactive rats with normotensive mean systolic blood pressure levels, and we have designated the new strain as the Wistar-Kyoto hyperactive (WK/HA) rat. Another behavioral characteristic of the SHR rat, poor habituation in a nonreinforcing novel environment, did not appear as a characteristic trait of the new strain of WK/HA rats, suggesting a separate underlying genetic basis for the two traits that had been apparently fortuitously fixed in the SHR genotype as a result of intensive inbreeding of that strain. The new WK/HA strain, together with the WKY control strain, is considered as more suitable for subjects in studying hyperactivity in rats than the original SHR strain with its concomitant hypertension and poor habituation traits.     

A developmental-genetic analysis of aggressive behavior in mice: IV. Genotype-environment interaction

To assess the extent of plasticity in behavioral development after directional selection for aggressive behavior, male mice were reared and tested in selected social rearing and testing conditions. After four generations of selective breeding, the lines differed in all attack measures when tested in a dyadic assessment following isolation rearing. Line-specific effects of isolation vs. group rearing were demonstrated, and longitudinal studies showed the ontogenetic pattern of difference between lines to be substantially changed by conditions of rearing and testing. The social-interactional processes that might produce the developmental genotype-environment interaction were investigated. Line-specific interaction patterns within long-established sibling groups predicted aggressive behavior in cross-situational dyadic assessments. Group rearing attenuated most line differences in aggressive measures, but the high-aggressive line was more likely than the low-aggressive line to persist in attacking over consecutive days of observation. Cross-fostering in early development did not significantly change adult aggressive behavior. Some implications of a developmental-genetic approach to the study of social interactions are discussed.     

Précis of The brain and emotion

The topics treated in The brain and emotion include the definition, nature, and functions of emotion (Ch. 3); the neural bases of emotion (Ch. 4); reward, punishment, and emotion in brain design (Ch. 10); a theory of consciousness and its application to understanding emotion and pleasure (Ch. 9); and neural networks and emotion-related learning (Appendix). The approach is that emotions can be considered as states elicited by reinforcers (rewards and punishers). This approach helps with understanding the functions of emotion, with classifying different emotions, and in understanding what information-processing systems in the brain are involved in emotion, and how they are involved. The hypothesis is developed that brains are designed around reward- and punishment-evaluation systems, because this is the way that genes can build a complex system that will produce appropriate but flexible behavior to increase fitness (Ch. 10). By specifying goals rather than particular behavioral patterns of responses, genes leave much more open the possible behavioral strategies that might be required to increase fitness. The importance of reward and punishment systems in brain design also provides a basis for understanding the brain mechanisms of motivation, as described in Chapters 2 for appetite and feeding, 5 for brain-stimulation reward, 6 for addiction, 7 for thirst, and 8 for sexual behavior.     

Effects of acute and chronic stress and of genotype on oxotremorine-induced locomotor depression of mice

The locomotor behavior of unstressed and stressed mice of two inbred strains, DBA/2 and C57/BL6, was investigated. Animals were tested in a toggle-floor box apparatus, 30 min after saline or oxotremorine treatment (ip). A dose of oxotremorine that did not depress the activity of na?ve mice (0.01 mg/kg) was chosen. Stressed mice were injected 24 h after either a single 2-h stress session (acute stress) or the last of 14 daily stress sessions of tube restraining (chronic stress). Acute stress did not modify the depressant effect of oxotremorine on locomotor behavior in either strain. On the contrary, chronic stress induced a clear sensitization of DBA but not C57 mice to the depressant effect of oxotremorine. These findings show that chronic stress may result in modifications of the cholinergic function, and its behavioral correlates, and that these changes are modulated by the genetic makeup.     

Behavior genetic analysis of Water-T-Maze learning in inbred strains of mice,their hybrids,and selected second generation crosses

Summary The Water-T-Maze was used to investigate the genetically determined apparatus-dependent behavior of mice. Special importance was attached to the mode of inheritance involved. For this purpose we used NMRI, C3H/HeJ, Balb/c, Balb/cN, DBA/2, C57Bl/6 inbred mouse strains, together with their offspring and the F₂-hybrids of C3H/HeJ and DBA/2. Furthermore investigations were carried out to examine the effect of the environment on the expression of behavior. After these experiments had proved that there is a predominantly genetic derivation for behavioral expression, a possible relationship between the conditioning effect and the age of the animals was investigated. The animal's age has quantitative effects on the expression of behavior, but it does not lead to any qualitative behavioral changes. Nevertheless early conditioning of the animals apparently manifests itself in long-term memory. On the whole the mode of inheritance in Water-T-Maze learning appears to imply a polygene-dependent model in which clear dominant effects are present, as shown in the results of the F₂-generation. No sex-related differences were observed. In general, the results demonstrate a definite involvement of genetic factors in the areas of conditioning and behavior.     

Measurements of the behavioral effects of albino mutation in mice (Mus musculus): comparisons of coisogenic inbred and hybrid lines

The effects of the albino gene on mouse behavior were examined, in particular its possible interactions with nonallelic genes (epistasis). More generally, the possible effects of genetic background (inbreeding depression or hybrid vigor) on the effects of the mutation were also considered. Tasks requiring either predominantly motor or predominantly cognitive capacity were studied for coisogenic albino and pigmented mice from either an inbred strain (C57BL/6 c/c vs. C57BL/6 +/c) or an F1 heterozygous generation (F1 c/c vs. F1 +/c) from a BALB/c X C57BL/6 +/c cross. The results showed a clear albino gene effect in the two lines and provide further evidence that the gene is the effective factor. On the other hand, there was no significant interaction between the mutation and the genotypic group (C57BL/6 or F1), which indicates that the effects of the mutation act approximately in an additive fashion between loci in these groups.     

Septal lesions and behavior: effects of presurgical rearing and strain of mouse.

Male mice (C57BL/10J or SJL/J strains) were reared in either enriched social cages or restricted individual cages from 25 days of age until they underwent septal or control surgery 1 mo later. Enrichment differentially altered septal or control behavior as measured by: fluid consumption of water, saccharin, and quinine; performance on a rotorod; and the acquisition of an active avoidance task. The interactions of presurgical history with brain damage were manifested differently in the two strains of mice. The importance of attending more to genetic and presurgical history in attempts to define the effects of brain damage on behavior and to determine the function of brain structures is discussed.     

Genetic differences in response to novelty and spatial memory using a two-trial recognition task in mice

A two-trial memory task, based on a free-choice exploration paradigm in a Y-maze, was previously developed to study recognition processes in Sprague-Dawley rats. Because this paradigm avoids the use of electric shock or deprivation that may have nonspecific effects and does not require learning of a rule, it may be particularly useful for studying memory in mice. Four inbred strains (Balb/cByJ, DBA/2J, C57BL/6J, and SJL/J), an F1 hybrid (C57BL/6 x SJL/J), and one outbred strain (CD1) were used to validate this task in mice and to characterize a strain distribution in response to novelty and working memory. Exploration was measured with a short (2 min) intertrial interval (ITI) between acquisition and retrieval, while memory was examined with longer intervals (30 min, 1 h, and 2 h). A study of the time course of the response to novelty revealed varying degrees of preference and/or habituation to novelty among the different strains, with CD1 exhibiting a very high response to novelty and others showing lower (C57 x SJL hybrids) to complete absence (SJL) of exploration of novelty. Memory span, assessed with increasing ITIs, varied widely among strains from 30 min (C57 x SJL hybrids) to at least 2 h (C57 and BALB). Such demonstrated sensitivity to a wide range of behavioral phenotypes supports the use of this spatial memory task as an effective tool for the study of genetic influences on the response to novelty and recognition processes in mice.     

The factor-gene basis of emotionality

This paper presents the empirical and theoretical evidence in support of the factor-gene model of emotionality. The theory views the expression of emotion as a product of the interaction between cognition and affect, where cognition and affect are each defined as complex systems whose wholistic functioning (cognition interprets inputs and affect controls arousal level) follows the principles of systems and information-processing theory and whose components are identified via factor analysis. On the basis of the empirical identification of factors at the 1st, 2nd, and 3rd strata, it has been hypothesized that the factors in each domain (33 cognitive factors and 31 affective factors) are hierarchically organized. The empirical research also indicates a significant hereditary effect for 31% of the factors in the cognitive domain and for 83% of the factors in the affective domain. The most pervasive experimental finding concerning the mode of inheritance is that each factor is polygenically determined. Furthermore, in the affective domain there is a range of dominance effects, depending on the class of factors. That is, factors related to escape and avoidance are governed by complete or overdominance, and some of them (e.g., escape) also manifest directional dominance, whereas factors related to undifferentiated arousal (e.g., autonomic balance) manifest either partial dominance or an intermediate form of inheritance. In brief, the factor-gene model is a multiple factor model at both the behavioral (i.e., the factors identified by factor analysis) and genetic (i.e., many genes accounting for each behavioral factor) levels. Futhermore, factors and genes are linked via a variety of unspecified, intervening (and to date unknown) psychobiological mechanisms.The experimental aspects of the author's research summarized in this review were supported by grants from the National Research Council of Canada, and the theoretical aspects were supported by grants from the Canada Council.     

Children's use of frequency information for trait categorization and behavioral prediction

Two experiments examined young children's use of behavioral frequency information to make behavioral predictions and global personality attributions. In Experiment 1, participants heard about an actor who behaved positively or negatively toward 1 or several recipients. Generally, children did not differentiate their judgments of the actor on the basis of the amount of information provided. In Experiment 2, the actor behaved positively or negatively toward a single recipient once or repeatedly. Participants were more likely to make appropriate predictions and attributions after exposure to multiple target behaviors and with increasing age. Overall, children's performance was influenced by age-related positivity and negativity biases. These findings indicate that frequency information is important for personality judgments but that its use is affected by contextual complexity and information-processing biases.