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A larger group of 70--75 years aged subjects was studied by means of various cutaneous tests, by E-rosette formation and by blastogenic response and 18 people showing a depressed cellular immunity were selected. These subjects and a similar control group with normal C.M.I. were further investigated in various condition of stimulation for cellular response in inflammation, chemotaxis, phagocytic activity and polysaccharide content in the granulocyte citoplasm. In general the former activity was not depressed, chemotaxis and phagocytic values were deficient, polysaccharide content appeared the same in the normal (control) and in the immune deficient group.
OBJECTIVE: To compare the behaviors of black, white, and Hispanic children who were 18 months to 18 years of age and exposed to intimate partner violence with an age- and ethnically similar sample of children who were not exposed to violence and to compare both exposed and nonexposed children to normative samples. METHODS: As part of a study on treatments for abused women in primary care public health clinics and Women, Infants and Children clinics in a large urban area, 258 abused mothers completed the Child Behavior Checklist (CBCL) on 1 of their randomly selected children between the ages of 18 months and 18 years. An ethnically similar sample of 72 nonabused mothers also completed the CBCL. The CBCL is a standardized instrument that provides a parental report of the extent of a child's behavioral problems and social competencies. The CBCL consists of a form for children 18 months to 5 years and a version for ages 6 to 18 years. The CBCL is orally administered to a parent, who rates the presence and frequency of certain behaviors on a 3-point scale (0 = not true, 1 = somewhat or sometimes true, and 2 = very true or often true). The time period is the last 6 months for the child 6 to 18 years of age and 2 months for the child 18 months to 5 years of age. Examples of behaviors for the child age 6 to 18 years include "gets in many fights," "truancy, skips school." Examples of behaviors for the child 18 months to 5 years of age include "cruel to animals," "physically attacks people," and "doesn't want to sleep alone." Both forms of the CBCL consist of 2 broadband factors of behavioral problems: internalizing and externalizing with mean scale scores for national normative samples as well as clinically referred and nonreferred samples of children. Internalizing behaviors include anxiety/depression, withdrawal, and somatic complaints. Externalizing behaviors include attention problems, aggressive behavior, and rule-breaking actions. Behavior scales yield a score of total behavioral problems. Scores are summed and then converted to normalized T scores. T scores >or=60 are within the borderline/clinical referral range-higher scores represent more deviant behavior. Multivariate analyses of variance (MANOVAs) were used to determine whether children from abused mothers differed significantly in their internalizing behaviors, externalizing behaviors, and total behavior problems from children of nonabused mothers. One sample t tests were used to compare children from abused and nonabused mothers to the matched clinically referred and nonreferred normative sample. Four pair-wise comparisons were considered: 1) children from abused women to referred norm, 2) children from abused women to nonreferred norm, 3) children from nonabused women to referred norm, and 4) children from nonabused to nonreferred norm. The internal, external, and total behavior problem T scores were dichotomized into a referral status: nonreferred = T score < 60, referred = T score >or= 60. Frequencies and percentages were used to describe the distribution of referral status among the children from the abused and nonabused women, and chi(2) tests of independence were used to determine whether the groups were significantly different. RESULTS: No significant differences in demographic characteristics between children from the abused women and nonabused women were observed. The sample consisted of a large number of Hispanic children (68.9%) and slightly more girls (53.6%), and nearly half (45.2%) had annual household incomes <10,000 dollars. Means, standard deviations, and results from the MANOVAs performed on internal, external, and total behavior problem scores between children from abused and nonabused women revealed no significant differences (F[3,139] = 1.21) for children ages 18 months through 5 years. Results from the MANOVA performed for ages 6 through 18 years revealed a significant group difference (F[3,183] = 3.13). Univariate tests revealed significant group differences for internalizing behavior (F[1,185] = 6.81), externalizing behav = 6.81), externalizing behavior (F[1,185] = 7.84), and total behavior problems (F[1,185] = 9.45). Overall, children of abused mothers had significantly higher internalizing (58.5 +/- 12.1), externalizing (55.5 +/- 12.4), and total behavior problems (57.6 +/- 12.3) scores than the internalizing (52.9 +/- 13.7), externalizing (49.7 +/- 10.6), and total behavior problems (51.0 +/- 13.0) scores exhibited for children of nonabused mothers. Most comparisons of children from the abused women to the referred and nonreferred norms are significant. The mean internal, external, and total behavior problem scores from children of abused women were significantly higher than the nonreferred norms and significantly lower than the referred norms. In contrast, all comparisons for children from nonabused women were not significantly different from the nonreferred norms. CONCLUSIONS: Children, ages 6 to 18 years, of abused mothers exhibit significantly more internalizing, externalizing, and total behavior problems than children for the same age and sex of nonabused mothers. In addition, the mean internalizing behavior score for boys 6 to 11 years of age as well as girls and boys 12 to 18 years of age of abused mothers were not significantly different from the clinical referral norms. Internalizing behaviors of anxiety, withdrawal, and depression are consistent with suicidal risk. The association of a child's exposure to intimate partner violence and subsequent attempted and/or completed suicide demands research. Our data demonstrate that children of abused mothers have significantly more behavioral problems than the nonclinically referred norm children but also, for most children, display significantly fewer problems than the clinically referred children. These children of abused mothers are clearly suspended above normal and below deviant, with children ages 6 to 18 being at the greatest risk. If abused mothers can be identified and treated, then perhaps behavior problems of their children can be arrested and behavioral scores improved. The American Academy of Pediatrics Committee on Child Abuse and Neglect recommends routine screening of all women for abuse at the time of the well-child visit and implementation of a protocol that includes a safety plan for the entire family. Clinicians can use this research information to assess for intimate partner violence during child health visits and inform abused mothers of the potential effects on their children's behavior. Early detection and treatment for intimate partner violence against women has the potential to interrupt and prevent behavioral problems for their children.
The purpose of this study was to elucidate the etiological pathways towards substance use and risky sexual behavior in female adolescent substance abusers. The study had three aims: (1) to determine the relations between behavioral dysregulation, negative affectivity, and childhood victimization with substance use and risky sexual behavior, (2) to determine whether these relations are mediated by internalizing symptomatology, antisocial behavior, and affiliating with an adult boyfriend; and (3) to determine whether age of menarche moderates the relation between the mediating variables and substance use and risky sexual behavior. Multiple behavioral, psychiatric interview, and self-report measures were used to index behavioral dysregulation, negative affectivity, childhood victimization, internalizing symptomatology, antisocial behavior, affiliation with adult boyfriends, substance use, and risky sexual behavior in 125 substance abusing female adolescents and 78 controls between the ages of 14-18 years. Structural equation modeling was used to determine the etiological pathways. Results indicated that behavioral dysregulation, negative affectivity, and childhood victimization were related to substance use and risky sexual behavior. Age of menarche was significantly correlated with affiliation with an older boyfriend and risky sexual behavior. Antisocial behavior mediated the associations between behavioral dysregulation, negative affectivity and childhood victimization with substance use and risky sexual behavior. Affiliation with an adult boyfriend was directly associated with substance use involvement and accounted for the relationship between chronological age and risky sexual behavior. Finally, late menarche enhanced the association between internalizing symptomatology and substance use involvement. The results highlight the importance of behavioral dysregulation, negative affectivity, and childhood victimization in predicting substance use and risky sexual behavior, as well as the finding that antisocial behavior and affiliation with an adult boyfriend may be etiologically important in predicting these outcomes. Therefore, from a prevention and treatment standpoint, behavioral and affective dysregulation, childhood victimization as well as antisocial behavior may serve as clinical 'gateways' for altering the developmental trajectory toward substance use and risky sexual behavior in high risk and substance abusing youth. For example, reducing dysregulation through behavior modification procedures that have been developed for conduct disordered children would appear to be a heuristic avenue of investigation emanating from the results obtained in this study.
The elevation of central corticotropin releasing factor (CRF) causes an increase in behavioral activity, including increases in overall activity and oral/nasal/facial (ONF) chewing-rooting-rubbing behaviors in the pig and similar behaviors in other species. This study detailed changes in the frequency, duration and sequences of behaviors after central administration of vehicle or porcine CRF (pCRF at 0.5, 5.0, 50 and 150 microg). A sequential analysis described the complex behaviors induced in a dose-dependent fashion by central pCRF. The frequency and duration of ONF behaviors were significantly increased among pigs receiving 50 microg of pCRF. For behaviors such as ONF, 50 microg represented a breakpoint at which the frequency and duration of single behaviors increased. Pigs receiving 50 microg of pCRF were considerably more active and exhibited more ONF behaviors than did pigs receiving lower doses. The highly sensitive sequential analysis revealed that very low doses of central pCRF induced subtle changes in sequences of behaviors. Low doses of central pCRF (0.5 microg) induced fear-related behavioral sequences that included ONF behaviors alternating with periods of inactivity. Central injection of astressin, a CRF receptor antagonist, blocked many, but not all, of CRF-induced behaviors. Compared with saline-injected control pigs, central pCRF increased general activity, ONF, fear-related freezing and sham chewing behaviors. When pCRF was given following astressin, fear-related freezing behaviors were not different compared with pigs receiving saline. However, pigs given astressin plus pCRF showed elevated sham chewing compared with saline-injected control pigs, as did pigs receiving intracerebroventricular (ICV) pCRF. These data indicate that central pCRF activates brain mechanisms associated with hyperactivity, ONF and fear-related behaviors, whereas other behaviors induced by pCRF may be nonspecifically mediated by CRF. Astressin antagonized some, but not all, pCRF-induced behaviors. This model represents the induction of hyperactivity and stereotyped behaviors, which may represent a new model for the study of mania or obsessive-compulsive behaviors.
Behavior for mammals is built out of multiple muscles acting in a coordinated fashion. Prima facie, there are three principal ways to increase an animal's behavioral repertoire size. The first is to, for each new behavior type, create a set of new muscle types (e.g. triceps, sartorius, etc.) with new functions specifically devoted to the implementation of that behavior type. If this were the case, then although each behavior is built out of many muscles, behavior is not built in a combinatorial fashion out of muscles. The second is similar to the first in that new behavior types are implemented via new muscle types, but, instead, muscles are used in a combinatorial fashion, so that it is the combination of the new muscle type with existing muscle types that makes the new behavior type possible. This is analogous to the addition of new words in a language. The third way behavioral complexity may be scaled up is to increase the complexity of behavioral expressions themselves (rather than increasing the number of muscles types), namely by having more muscles involved in an average behavior. This is analogous to uttering longer sentences in a language. My main task in this paper is to examine which of these ways underlies the increase of behavioral complexity among mammals. Behavioral repertoire sizes from the ethology literature were accumulated for mammals from two dozen species across eight orders, and the number of muscle types was estimated from atlases of anatomy across eight mammalian orders. The manner in which behavioral complexity actually increases among mammals appears to favor the second possibility mentioned above: greater behavioral complexity is achieved primarily by increasing the number of muscle types, and by using muscles in a combinatorial fashion. The theoretical framework I describe allows us to interpret the manner in which the number of muscle types scales with behavioral repertoire size, and I conclude that the number of degrees of freedom in the construction of behavioral expressions is on the order of three, which is probably due to neurobiological limitations in forming behaviors. The ontogeny of behavior in rat is also discussed within this framework. Finally, I show that there is a strong positive relationship between behavioral repertoire size and encephalization among mammals.
The present article evaluates the quality and magnitude of the effects of lesion size and location and their interaction, on the behavioral performance of old world monkeys by a quantitative comparison of 283 published studies. The results indicate that lesion size alone is a poor predictor of the behavioral performance of monkeys, as opposed to Lashley's work in rats. Lesion location is a reliable predictor of the behavioral performance for brain regions thought to be primarily involved in a specific behavior; however, similar behavioral effects, although less reliable, can be observed for many different lesion loci, suggesting a specialized and a holistic brain functioning to be working at the same time. Some lesion loci are, in sharp contrast to current hypotheses about functional localization in the brain, not associated with impairments, but with significant improvements of a specific behavior. For such lesion loci the correlation of lesion size and behavioral performance may yield significant positive relationships (that is, increasing behavioral improvement with increasing lesion size); these relationships are contrasted by the significant negative relationships obtained for lesions of brain regions thought to be primarily involved in a given behavior. Thus, the lesion size may be a good predictor of the behavioral performance, depending on the lesion location and on the behavior under measurement. The behaviors analysed in this study were discrimination or delayed reaction or delayed matching-to-sample. The former two behaviors involve habit-like learning and are thought to be mediated by corticostriate functional pathways in the brain and the latter behavior implies the learning of single events, being thought to be mediated by corticolimbic functional pathways in the brain. Improved performances were observed for habit-like behaviors after lesions of brain regions (lateral frontal, premotor/motor, parietal, inferotemporal cortex, amygdala and fornix) being not primarily involved in a given behavior but possibly being able to inhibit the corticostriate pathways. Interestingly, lesions of subareas of the neostriatum were found to cause impairments in habit-like behaviors presumably being processed via these subareas (e.g. head of the caudate nucleus and delayed reaction), but to cause significant improvements in other behaviors (e.g. head of the caudate nucleus and visual discrimination). Thus, it may be concluded that diverse systems of functionally interconnected brain regions may maintain reciprocal inhibitions, with the result that a lesion within one system not only leads to a loss of one behavior, but in addition leads to a modification, may be a facilitation, of another behavior.(ABSTRACT TRUNCATED AT 400 WORDS)
In reviewing the literature on the use of behavioral therapy, Smyer, et al concluded that behavioral approaches involving the application of learning principles have been demonstrated to be effective as an intervention technique with the elderly for a variety of problems in a variety of settings. Specifically, studies have been reported in the literature that suggest that a behavioral approach can be applied to mediate certain behaviors of dementia patients. When using behavioral approaches, it is important to remember that the behavior of organisms is maintained by reinforcement. That is to say, if a person exhibits a behavior, it is because the behavior is meeting a need. For the behavior to be changed, either the need has to be satisfied by a different behavior, or the behavior has to have a different consequence. Behavioral approaches are extremely powerful in maintaining and changing behavior and often occur coincidentally. To change behavior purposefully, it is important to keep in mind that the meeting of needs by a different specific behavior or the reinforcement of a new behavior needs to be consistent for the entire daily environment. Despite the fact that research supports the effectiveness of behavioral interventions for specific behavioral problems, these strategies have not seen widespread use in nursing home settings. Another reason for the limited use of behavioral approaches may be that nursing home professionals are not aware of the effectiveness of such interventions. Other reasons for the limited use of behavioral approaches in long-term care settings may be that implementation requires not only caregiver training, but also consistent maintenance of appropriate environmental contingencies.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVE: There were two main aims: first, to assess parental attributions about child behavior in abuse-risk and nonclinic parents. Second, to assess how attributions predict affective and behavioral reactions to child behavior. METHOD: Internal-external attributions relating to the causes of child behavior were compared across mothers at-risk of child abuse (n = 40) and mothers who reported no significant parental or child conduct or behavior problems (n = 20). Mothers' attributions about the causes of the behavior of their own child and an unfamiliar child were recorded in response to the presentation of videotaped excerpts of the behavior. RESULTS: Results highlighted that compared with nonclinic mothers, abuse-risk mothers had a tendency to attribute positive child behavior to more external causes and negative child behavior to more internal causes. Differences were also found between parental cognitions about clearly positive, clearly naughty, and ambiguous child behavior. In the abuse-risk group, positive child behavior predicted coercive parenting when it elicited angry feelings in the mother; ambiguous and naughty child behavior led to coercive parenting through valence ratings of "deviant" and attributions of "internality." Analyses within the abuse-risk group showed that parental attributions are predictive of parental coerciveness for unfamiliar behavior. As behavior becomes more familiar, ratings of its valence and the affect it elicits override attributional activity. CONCLUSIONS: Parental attributions about the causes of child behavior differ according to the valence and familiarity of that behavior, and discriminate between parents at risk for child abuse. Further, attributions are predictive of the affective and behavioral responses the parent makes to the child's behavior for ambiguous or unfamiliar behavior. Evidence was found for the validity of using videotaped stimuli of the behavior of known and unknown children as a method of assessing parental attributions.
PURPOSE: To examine associations among risk and protective factors with negative (substance use, delinquent behavior, sedentary recreation, empty calorie consumption, suicidal behavior) and positive behaviors (prosocial recreation, productive behavior, exercise, nutrition behavior, academic achievement, seatbelt use). METHODS: Data were from sixth-grade public school students (n = 133,629) in 2001. Factor analysis produced five risks, five protectors, seven negative and six positive behaviors. Associations were tested among single and cumulative risks and protectors with behaviors (linear, logit regression) and combinations of high and low risks and protectors with behaviors (analysis of variance, Chi-square). RESULTS: Individual and cumulative risks were related to higher and protectors were related to lower negative behaviors. Protectors were associated with higher positive behaviors, with some exceptions. Risks and their sum were associated with lower academic achievement and seatbelt use, but were linked to higher, rather than lower productive behavior. Being bullied or victimized was correlated with higher levels of exercise, good nutrition, and prosocial recreation. The high risk/low protection combination had the highest negative behaviors and low risk/high protection the lowest, but for positive behaviors, high protectors with either high or low risks showed higher positive behaviors. CONCLUSIONS: These findings provide new information about how (a) risks and protectors are associated with negative behaviors besides substance use and delinquency, (b) cumulative protectors, as well as risks, are related to negative and positive behaviors, and (c) combinations of high and low risks and protectors are related to behaviors. The unusual findings for positive behaviors merit further exploration.
OBJECTIVE: To examine the evolution of risk behaviors over 2 years among a community-based cohort of low-income African American preadolescents and young adolescents enrolled in a randomized trial of an acquired immunodeficiency syndrome risk reduction intervention. DESIGN: Longitudinal, community-based cohort. SETTING: Nine recreation centers serving 3 public housing developments. SUBJECTS: Three hundred eighty-three African American youths aged 9 through 15 years at baseline. INTERVENTIONS: Frequency distributions, chi 2 analyses, and regression analyses regarding 10 risk behaviors were conducted. To assess whether a specific risk behavior or its protective (nonrisk) behavioral analogue, composing a risk-nonrisk behavioral complex (eg, was sexually active and was sexually abstinent or used drugs and refrained from drugs), was stable over time, kappa values were determined for the 10 risk-nonrisk behavioral complexes. MAIN OUTCOME MEASURES: Instrument assessing risk/ behaviors administered at baseline and every 6 months aurally and visually via talking computer. RESULTS: The prevalence of sexual intercourse, cigarette smoking, alcohol consumption, and drug use increased notably over time. Drug use increased from a 6-month cumulative prevalence of 7% at baseline to 27% at the 24-month follow-up (P < .001). Cumulatively over the 2-year study interval, 81% of youths had engaged in fighting, 58% had engaged in sexual intercourse, and from 33% to 40% had engaged in truancy, knife or bat carrying or both, alcohol consumption, drug use, and cigarette smoking. All of the risk-nonrisk behavioral complexes except weapon carrying were stable during the semiannual assessment intervals. Fighting (kappa = 0.22, P < .01), sexual intercourse (kappa = 0.33, P < .001), alcohol consumption (kappa = 0.21, P < .001), and unprotected sexual intercourse (kappa = 0.34, P < .05) were stable for 2 years. Six risk-nonrisk behavioral complexes were stable for the 2-year interval among youths aged 13 through 15 years at baseline, while only 2 risk-nonrisk behavioral complexes were stable among younger youths. The intervention seemed to affect the stability of 4 risk behaviors: truancy, drug use, unprotected sexual intercourse, and, possibly, fighting. For unprotected sexual intercourse, this intervention effect seemed to be due to stabilization of nonparticipation in risky behavior. Intervention youths were less likely to adopt a risk behavior (ie, engage in it for > or = 2 risk assessment periods) than control youths, but they were not less likely to experiment with a risk behavior. CONCLUSIONS: There is evidence that although the prevalence of risk behaviors does change with age, most risk-nonrisk behavioral complexes seem to be relatively stable over time and stability may increase with time. Risk reduction interventions seem to decrease risk adoption, stabilize nonrisk behaviors, and possibly destabilize risk behavior.
PURPOSE: To examine: (a) the effects of acculturation on a healthy lifestyle including problem behaviors (substance use and sex acts) and health-promoting behaviors (e.g., seat belt use, vitamin intake, hours of sleep per night) and (b) the interrelationships among problem and health-promoting behaviors among Latino adolescents. METHODS: Face-to-face interviews were conducted with Latino adolescents (n = 609) with questions covering the following areas: acculturation, sociodemographics, problem behaviors, and health-promoting behaviors. The participants ranged in age from 11 to 19 (mean = 15) years. Bivariate correlations and factor analyses were used to examine the relationship between problem and health-promoting behaviors. A combination of one-way analyses of variance (ANOVAs), Chi-square tests, and Student's t-tests were used to analyze the effects of acculturation on problem and health-promoting behaviors. RESULTS: Higher levels of acculturation were associated with an increased likelihood of exhibiting problem behaviors and a decreased likelihood of exhibiting certain health-promoting behaviors. Foreign-born Latinos were significantly less likely to engage in problem behaviors. Problem behaviors were likely to co-occur; however, the co-occurrence of health-promoting behaviors was not evident. The results also revealed the co-occurrence of problem behaviors with selected health-promoting behaviors. CONCLUSIONS: Among Latino adolescents, there seems to be evidence that problem behaviors and certain health-promoting behaviors do co-occur. To the extent that "healthy lifestyles" are conceptualized as the presence of health-promoting behaviors and the absence of problem behaviors, less acculturated Latino adolescents seem to fare better than those that are more acculturated. Interventions to promote "healthy lifestyles" among Latino adolescents should be tailored to take into consideration the effect of acculturation.
Continuous observations are an accurate method for behavioral measurements but are difficult to conduct on large numbers of animals because of extensive labor requirements. Thus, we sought to develop methods of behavioral data collection in feedlot cattle production systems that reasonably approximated continuous sampling. Standing, lying, feeding, drinking, and walking behaviors were examined from 224 h of continuous video from 64 heifers. Experiment 1 (n = 24 heifers) compared continuous behavioral sampling techniques (Continuous) with scan sampling using intervals of 1, 5, 10, 15, 30, and 60 min and time sampling (a technique for the periodic recording of behavior) for the first 10 min out of every 60 min. Means for each scan sampling method did not differ in estimated percentage of duration of behaviors (P > 0.05) from continuous sampling, except for scan sampling with a 60-min interval. Scan sampling with a 60-min interval differed from more frequent scan sampling intervals for all behaviors except lying. Scan sampling with short intervals (1 and 5 min) was correlated highly with Continuous for all behaviors. The longer the scan interval, the lower the correlations, especially for behaviors with short duration. Time sampling was not an accurate technique for measuring the sampled behaviors. Focal animal sampling (using continuous sampling of individuals) indicated that one heifer was representative of the entire pen of 10 animals (Continuous) for all maintenance behaviors except drinking. Scan sampling methods (1-, 5-, 10-, and 15-min intervals) were accurate methods of behavioral sampling for feedlot cattle, but scan intervals of 30 or 60 min were less accurate and less precise. Time sampling was not an accurate method because it overestimated standing and underestimated lying behaviors. Experiment 2 (n = 40 heifers) investigated the number of focal animals required to accurately represent continuous behavioral sampling for all animals. Focal animal sampling was accurate for most behaviors using as few as 1 animal out of 10 but was not an accurate method for drinking behavior unless 40% of the animals in the pen were observed. Estimates of sample sizes needed for experimental protocols are provided. Behavioral means, standard deviations, and coefficients of variation are presented along with estimates of required sample sizes. These results validate accurate, precise, and efficient methods for quantifying feedlot cattle behavior.
Early workers interested in the mechanisms mediating sex differences in morphology and behavior assumed that differences in behavior that are commonly observed between males and females result from the sex specificity of androgens and estrogens. Androgens were thought to facilitate male-typical traits, and estrogens were thought to facilitate female-typical traits. By the mid-20th century, however, it was apparent that administering androgens to females or estrogens to males was not always effective in sex-reversing behavior and that in some cases a "female" hormone such as an estrogen could produce male-typical behavior and an androgen could induce female-typical behavior. These conceptual difficulties were resolved to a large extent by the seminal paper of C. H. Phoenix, R. W. Goy, A. A. Gerall, and W. C. Young in (1959, Endocrinology 65, 369-382) that illustrated that several aspects of sexual behavior are different between males and females because the sexes have been exposed during their perinatal life to a different endocrine milieu that has irreversibly modified their response to steroids in adulthood. Phoenix et al. (1959) therefore formalized a clear dichotomy between the organizational and activational effects of sex steroid hormones. Since this paper, a substantial amount of research has been carried out in an attempt to identify the aspects of brain morphology or neurochemistry that differentiate under the embryonic/neonatal effects of steroids and are responsible for the different behavioral response of males and females to the activation by steroids in adulthood. During the past 25 years, research in behavioral neuroendocrinology has identified many sex differences in brain morphology or neurochemistry; however many of these sex differences disappear when male and female subjects are placed in similar endocrine conditions (e.g., are gonadectomized and treated with the same amount of steroids) so that these differences appear to be of an activational nature and cannot therefore explain sex differences in behavior that are still present in gonadectomized steroid-treated adults. This research has also revealed many aspects of brain morphology and chemistry that are markedly affected by steroids in adulthood and are thought to mediate the activation of behavior at the central level. It has been explicitly, or in some cases, implicitly assumed that the sexual differentiation of brain and behavior driven by early exposure to steroids concerns primarily those neuroanatomical/neurochemical characteristics that are altered by steroids in adulthood and presumably mediate the activation of behavior. Extensive efforts to identify these sexually differentiated brain characteristics over the past 20 years has only met with limited success, however. As regards reproductive behavior, in all model species that have been studied it is still impossible to identify satisfactorily brain characteristics that differentiate under early steroid action and explain the sex differences in behavioral activating effects of steroids. This problem is illustrated by research conducted on Japanese quail (Coturnix japonica), an avian model system that displays prominent sex differences in the sexual behavioral response to testosterone, and in which the endocrine mechanisms that control sexual differentiation of behavior have been clearly identified so that subjects with a fully sex-reversed behavioral phenotype can be easily produced. In this species, studies of sex differences in the neural substrate mediating the action of steroids in the brain, including the activity of the enzymes that metabolize steroids such as aromatase and the distribution of steroid hormone receptors as well as related neurotransmitter systems, did not result in a satisfactory explanation of sex differences in the behavioral effectiveness of testosterone. Possible explanations for the relative failure to identify the organized brain characteristics responsible for behavio