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PubMed1995

Normative developmental behavior with implications for health and health promotion among adolescents: a Swedish cross-sectional survey.

I describe behavior with impact on health in adolescents against the background of characteristics of the Swedish society and analyse possible areas for improvement. A total of 4500 adolescents, aged 13-18 yr, in seven areas answered an anonymous questionnaire. Their socioeconomic backgrounds reflected mainstream adolescents. The response rate was 80-85%. Questions concerned health habits, exploratory behaviors regarding sexuality, use of alcohol and tobacco, problem behaviors, such as getting drunk, and life quality. There was very little experimentation with regard to health habits learned in childhood. Rapid adaptation to adult life-styles occurred, which was similar in both sexes in the younger age groups, but there were significant differences among older students. Alcohol use is of considerable concern. Adolescent prediction of future behavior indicated that negative behaviors require intervention. Parental influence on adolescent behavior needs to be explored. Peer groups could be an additional area for intervention.

Adolescent↗

PubMed1989

Implementation of a primary screen for developmental neurotoxicity.

A battery of tests to evaluate physical growth/development and neurobehavioral function was conducted with 78 litters of control Sprague-Dawley rats given purified water by intubation. The objectives of this study were to optimize test methods and to document the range and variability of the experimental endpoints. Data are presented for maternal evaluations (body weight gain, food consumption), gestation length, litter size, and postnatal survival. Pup body weight was used to assess postnatal somatic growth rate from birth to 85 days of age, while whole and regional brain weight measurements at 7, 28, and 85 days provided a more specific measure of physical growth relevant to a neurobehavioral study. Physical landmarks of development evaluated were pinna unfolding, incisor eruption, and eye opening while reflex landmarks of development evaluated were the negative geotaxis and pupillary reflexes. The mean percentage of litters acquiring a physical trait or reflex increased sigmoidally with age, and the data suggest that the potential to detect developmental delays would be optimal when ca. 90% of control litters reach the test landmark. Functional evaluations were arranged according to four testing subsets so that each litter was evaluated in each test (1 pup/sex/litter), but repeated testing on pups was minimized. Auditory and tactile startle reflexes, as well as prepulse inhibition, were measured at ages 22 days and 60-64 days and found to increase with age. A passive avoidance paradigm (age 40-43 days) was used to assess exploratory behavior (approach) and memory (avoidance). Swimming performance in a water maze was used to evaluate learning. In this test, escape times and error rates improved to their highest level by five or six trials and showed acceptable degrees of variability. Spontaneous motor activity was monitored for 23 hr at age 54-61 days to evaluate exploratory activity, photoperiod entrainment, and catecholamine-induced locomotion (amphetamine challenge). Finally, landmarks of sexual maturation (balanopreputial separation evident at 45 days of age, vaginal perforation evident at 33 days) and estrous cyclicity (4.8 cycles per 21 days) were evaluated as measures of reproductive neuroendocrine function. In sum, the test battery provided an efficient yet comprehensive screen for evaluating effects on physical growth/development and neurobehavioral function which meets practical criteria for preclinical testing of pharmaceutical agents.

Animals↗

PubMed1989

Effects of desipramine on rat behavior are prevented by concomitant treatment with ethanol.

Ethanol prevents the decrease of the number of beta-adrenoceptors in the cerebral cortex induced by chronic treatment of rats with desipramine. The activation of the adenylate cyclase, the second messenger, by beta-adrenergic agonists is reduced somewhat less than after treatment with desipramine alone. The present paper examined the hypothesis that ethanol inhibits the neuronal adaptation to desipramine chronic treatment at the functional level as well. Desipramine reduced exploratory behavior (crossings, rearings) as did ethanol. Combined treatment attenuated the effect of desipramine. Cognitive performance was investigated using an active avoidance paradigm. Desipramine-treated rats did not learn the task in contrast to control animals. Again, combination treatment with ethanol improved the ability of the rats to perform the task. The activity of cerebral beta-adrenergic mechanisms was assessed by injection of salbutamol, a beta-adrenoceptor agonist in rats pretreated with 5-hydroxytryptophan (5-HTP). The augmentation of the 5-HTP-induced wet dog shake behavior by salbutamol was observed in all animals independent of the chronic treatment. However, rats treated with desipramine were less active than those treated with tap water or ethanol. The effect of desipramine in the presence of a high concentration of salbutamol was attenuated by ethanol. The observed increase of the number of wet dog shakes correlates with the function of these receptors. In two paradigms, spontaneous motility and apomorphine-induced hypothermia, ethanol did not affect the action of desipramine. It is noteworthy that desipramine acted in both situations within a short time period (minutes to hours). The findings strongly suggest that ethanol can prevent adaptive changes in the brain induced by chronic treatment with the antidepressant desipramine. This is of special interest since the adaptation of beta-adrenoceptors is thought to be critical for the antidepressant efficacy of various therapeutic interventions applied in psychiatric practice.

5-Hydroxytryptophan↗

PubMed1984

Cerebral metabolic and circulatory effects of 1,1,1-trichloroethane, a neurotoxic industrial solvent. 1. Effects on local cerebral glucose consumption and blood flow during acute exposure.

The effects of inhaled 1,1,1-trichloroethane (3500, 6000, and 7800 ppm) on behavior, local cerebral blood flow, and local cerebral glucose consumption were studied in awake rats. The effect of the solvent inhalation on the EEG pattern and local cerebral blood flow was also studied in paralyzed animals under N2O analgesia. Exposure of awake animals to 6000 ppm 1,1,1-trichloroethane induced a decrease in motility and exploratory behavior. At 7800 ppm the rats were clearly ataxic. The local cerebral glucose consumption in 23 brain regions was studied by the [14C]deoxyglucose technique. A decrease was observed ranging from 14 to 55% of control values. The inferior colliculus and substantia nigra displayed the largest reductions. In exposed animals the local cerebral blood flow increased in 11 brain structures by 28-45%. In animals under N2O analgesia, 7400 ppm 1,1,1-trichloroethane induced a depression of the EEG activity. In these animals the local cerebral blood flow increased by 12-99%, with a large variability in blood flow between the different structures. It is concluded that exposure of rats to subanesthetic doses of 1,1,1-trichloroethane induces an increase in cerebral blood flow in spite of a concomitant decrease in glucose consumption and depression of cerebral function.

Anesthesia↗

PubMed1999

Normal inhibitory avoidance learning and anxiety, but increased locomotor activity in mice devoid of PrP(C).

Prions are the causative agents of transmissible spongiform encephalopathies. The transmissible agent (PrP(Sc)) is an abnormal form of PrP(C), a normal neuronal protein. The physiological role of PrP(C) remains unclear. In the present report, we evaluated behavioral parameters in Prnp(0/0) mice devoid of PrP(C). Prnp(0/0) mice showed normal short- and long-term retention of a step-down inhibitory avoidance task and normal behavior in an elevated plus maze test of anxiety. During a 5-min exploration of an open field, Prnp(0/0) mice showed normal number of rearings, defecation, and latency to initiate locomotion, but a significant increase in the number of crossings. The results suggest that Prnp(0/0) mice show normal fear-motivated memory, anxiety and exploratory behavior, and a slight increase in locomotor activity during exploration of a novel environment.

Animals↗

PubMed1997

A concussive-like brain injury model in mice (I): impairment in learning and memory.

The modeling of human concussive brain injury (CBI) in the laboratory has been challenging. In the present study, we developed an experimental CBI model in mice using a novel weight-drop device. Various injury levels were examined by adjusting the height of the falling weight (diameter 10 mm, length 20 cm, weight 21 g). At a height of 50 cm, the impact resulted in a mortality rate of 46.7% with a skull fracture rate of 28.6%. At a height of 25 cm, however, the impact produced a concussive-like brain injury (CLBI) to the mice without skull fracture. A series of pathophysiological and neurobehavioral responses was evaluated at this injury level. The CLBI mice lost muscle tone and righting reflex response immediately following the trauma and recovered from the latter within a short duration of 1.6 +/- 0.32 min (mean +/- SE). Brain edema formation started at 12 h, reached a maximum at 24 h and recovered 48 h. Typically edema was found in the neocortex, hippocampus, and cerebellum, but not in the brain stem. Deficits in the feeding behaviors lasted for 2 days, accompanied by lower body weight persisting for 5 days. The body weight growth rate for 24 h returned to the control levels by the third day postinjury. Learning and memory were evaluated at the end of 1-3 weeks after the trauma using a water-finding task. At 1 week, exploratory behaviors were slightly inhibited while learning and memory were profoundly impaired. Interestingly, the learning and memory deficits lasted for 2 weeks while recovering to the control levels by 3 weeks. No motor disability was found in the CLBI mice during the 3-week evaluations. These results indicate that the weight-drop impact produced graded injury to the brain, and at the injury level of 25 cm it produced a CLBI in the mice in which the characteristics of transient loss of neurobehavioral responses, short duration of brain edema, and long-lasting learning and memory deficits are similar to those of human CBI.

Animals↗

PubMed1999

Altered gene expression in striatal projection neurons in CB1 cannabinoid receptor knockout mice.

The basal ganglia, a brain structure critical for sensorimotor and motivational aspects of behavior, contain very high levels of CB1 cannabinoid receptors. These receptors are activated by endogenous lipophilic ligands, and they are thought to mediate behavioral effects of cannabinoid drugs. To evaluate the role of the endogenous cannabinoid system in the regulation of basal ganglia pathways, we have investigated the effects of targeted deletion of CB1 receptors on gene expression of various neuropeptides and transmitter-related enzymes in basal ganglia neurons. Mice without CB1 receptors are extremely hypoactive in a test for exploratory behavior (open-field test), showing markedly reduced locomotion and rearing. These CB1 mutants display significantly increased levels of substance P, dynorphin, enkephalin, and GAD 67 mRNAs in neurons of the two output pathways of the striatum that project to the substantia nigra and the globus pallidus. Our findings demonstrate that elimination of CB1 receptors results in behavioral abnormalities and functional reorganization of the basal ganglia.

Animals↗

PubMed1996

Mice homozygous for a modified beta-amyloid precursor protein (beta APP) gene show impaired behavior and high incidence of agenesis of the corpus callosum.

The amyloid precursor protein (beta APP) gene of the mouse was disrupted by homologous recombination; however, contrary to expectation, brain and other tissues still contained beta APP-specific RNA, albeit at a level 5-10 fold lower than wild-type and lacking the disrupted exon, which had been spliced out. The brain contained shortened beta APP-specific protein at a low level. Mutant mice were severely impaired in spatial learning and exploratory behavior and showed increased incidence of agenesis of the corpus callosum.

Agenesis of Corpus Callosum↗

PubMed1992

Corticotropin-releasing factor antagonist reduces emotionality in socially defeated rats via direct neurotropic action.

Introduction of a socially naive male rat into the home territory of a resident counterpart results in agonistic interactions, leading to the rapid social defeat of the intruder. Exposure to the aggressive resident produces a stress-response profile consisting of neuroendocrine activation and coping behaviors such as submission. The present studies examined the dependence of these adaptive responses on endogenous brain Corticotropin-Releasing Factor (CRF), a peptide hormone known to coordinate neuronally mediated- and pituitary-adrenal responses to stress. The Elevated Plus-Maze was employed as an animal model of emotionality in which stressors reduce subsequent exploration of open maze arms without walls in favor of enclosed maze arms. A CRF antagonist, alpha-hel CRF9-41, administered intracerebroventricularly (5 and 25 micrograms i.c.v.) immediately post-stress and 5 min prior to maze testing reversed the heightened emotionality produced by the resident exposure stressor. This action paralleled that of an anxiolytic dose of the short-acting benzodiazepine, midazolam (1.5 mg/kg i.p.). Intra-amygdaloid administration of lower doses of the CRF antagonist (125, 250 and 500 ng i.c.) also reversed, dose-dependently, the effect of exposure to an aggressive resident without altering the behavior of unstressed control animals. Further, the enhanced release of ACTH and corticosterone following social conflict was not modified over the short term by the intra-amygdaloid dose of CRF antagonist (250 ng i.c.) which was effective in reversing stress-induced hyper-emotionality. These results suggest that limbic system CRF substrates exert an anxiogenic effect on the exploratory behavior of socially defeated rats via a pituitary-adrenal-independent mechanism.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

Behavioral effects of 2,5-dimethoxy-4-methylamphetamine (DOM) in rats and mice.

The characteristics of the behavioral effects of 2,5-dimethoxy-4-methylamphetamine (DOM or STP) were compared with those of mescaline and methamphetamine in rats and mice. DOM significantly increased locomotor activity in an open-field situation at 0.5-1.0 mg/kg i.p., but at doses above 5 mg/kg i.p. caused biphasic changes, i.e. an initial decrease followed by an increase in motility and exploratory behavior. This hyperactivity was not accompanied by simultaneous increase in rearing. Besides, DOM induced head twitches in rats as well as in mice at doses above 0.1 mg/kg i.p., and marked backward locomotion only in rats at doses larger than 5 mg/kg i.p. The occurrence of backward locomotion might be attributable to the initial decrease in general activity. Behavioral effects of DOM were different from those of either mescaline or methamphetamine although they resembled those of mescaline in some respects.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1986

The behavioral effects of depletions of brain serotonin induced by 5,7-dihydroxytryptamine vary with time after administration.

Ether-anesthetized Sprague-Dawley rats were depleted of brain serotonin (5HT) by intraventricular injections of 50 micrograms 5,7-dihydroxtryptamine (57DHT). Oral pretreatment with 25 mg/kg desmethylimipramine was used to protect brain noradrenergic neurons from 57DHT. Liquid chromatographic assays revealed that this treatment did not significantly alter catecholamine levels but depleted hippocampal 5HT by 92% and striatal 5HT by 45%. Three or eleven days after lesioning, locomotor and exploratory behavior was characterized in separate groups of animals with a behavioral pattern monitor (BPM). On Days 4 and 12, the animals were retested following saline or 1.0 mg/kg amphetamine. Three days after depletion, lesioned rats exhibited a decrease rate of habituation of locomotor activity relative to controls. When challenged with amphetamine (1.0 mg/kg), 5HT-depleted rats exhibited increased corner and decreased center activity, as well as stereotyped patterns of locomotion. Eleven days following lesion, 5HT-depleted rats exhibited habituation rates greater than controls; amphetamine challenge yielded patterns of activity similar to those of control animals. These results show that central serotonergic pathways play an important role in modulating both spontaneous and amphetamine-elicited activity in rats, and that compensatory mechanisms operate over time to alter the behavioral effects of 57DHT-induced depletions of brain 5HT.

5,7-Dihydroxytryptamine↗

PubMed1990

Influence of early neonatal phenobarbital exposure on cerebral energy metabolism and behavior.

The influence of an early chronic phenobarbital (PhB) exposure on local cerebral glucose utilization (LCGU) and on behavior was studied in the rat. The animals were treated from Postnatal Day 2 to Postnatal Day 35 by a daily injection of 50 mg/kg PhB or by saline and tested between 10 and 35 days for short-term effects of the drug on LCGU and between 70 and 90 days for long-term effects of PhB on LCGU and behavior. PhB induced short- and long-lasting reductions in the overall rates of LCGU in hippocampal and cerebellar areas, but no significant changes in LCGU in the different cell layers of these two cerebral areas. PhB also changed the pattern of maturation of the rates of LCGU as compared to control subjects. The barbiturate treatment induced a decrease in the exploratory behavior of PhB- as compared to saline-treated rats in the open field, as well as a significant 25% decrease in the rate of spontaneous alternation with delay. In addition, PhB-treated rats needed significantly more time than control animals to perform their trials in the nonrewarded T maze testing. However, the neonatal barbiturate exposure did not induce changes in performances of adult rats in the rewarded eight arm maze. The results of the present study show that there is no apparent correlation between the rates of energy metabolism in the hippocampus and the impairment of learning abilities of adult rats in behavioral tests related to the hippocampus.

Animals↗

PubMed1999

The role of locus coeruleus in the regulation of cognitive performance.

Noradrenergic locus coeruleus (LC) neurons were recorded in monkeys performing a visual discrimination task, and a computational model was developed addressing the role of the LC brain system in cognitive performance. Changes in spontaneous and stimulus-induced patterns of LC activity correlated closely with fluctuations in behavioral performance. The model explains these fluctuations in terms of changes in electrotonic coupling among LC neurons and predicts improved performance during epochs of high coupling and synchronized LC firing. Cross correlations of simultaneously recorded LC neurons confirmed this prediction, indicating that electrotonic coupling in LC may play an important role in attentional modulation and the regulation of goal-directed versus exploratory behaviors.

Action Potentials↗

PubMed1998

Relationship of early infant state measures to behavior over the first year of life in the tufted capuchin monkey (Cebus apella).

Data on activity states were collected from 29 group-housed capuchin monkey (Cebus apella) infants for 3 h each week from birth to 11 weeks of age. The amounts of time spent in sleeping/drowsy, alert-quiet, and alert-active states were measured in these subjects. Videotaped observations of these infants were recorded 3 times/week in the home cage over the first year of life and were scored for a number of social and exploratory behaviors. The extent to which early infant activity state scores predicted later behavior in the home cage was examined. Infant state measures correlated significantly with home cage behavior during months 2-6 in that infants that had been more active in early infancy spent more time alone, with other animals, and in exploration and play and less time with mothers than did quieter infants. Early state measures were less successful in predicting home cage scores beyond 8 months of age, whereas differences in behavior attributable to housing variables became more salient in the latter part of the first year. There was also a negative correlation between mother and infant activity in months 2 and 3, in that more sedentary mothers tended to have more active infants.

Aging↗

PubMed1999

Male olfactory cues affect mothers' behavior in mice: effects of benzodiazepines.

RATIONALE: Threatening social stimuli were used in this study as aversive conditions to test anxiety in lactating female mice. The odors of potential infanticidal males or the "stress odor" left by restrained mice represented two aversive conditions that have been suggested to modulate the time spent by the mothers to reach their pups after 30 min of separation. OBJECTIVES: The effects of drugs acting at the benzodiazepine receptors were evaluated on the behavior of mothers exposed to different threatening social cues. METHODS: Lactating mice of the NMRI outbred strain with 8-day old pups were treated with (1) chlordiazepoxide (CDP) 2.5, 5.0 and 10 mg/kg i.p.; (2) flumazenil 10 mg/kg i.p. and (3) methyl beta-carboline-3-carboxylate (beta-CCM) 3.0 mg/kg i.p. RESULTS: The odors left by stressed females changed the mothers' exploratory behavior, but not the latency to reach pups. The latency was higher in the presence of cues from potentially infanticidal males. CDP (5.0 mg/kg) reduced the time spent to contact pups, whereas the other CDP doses did not modify the dam's behavior. Flumazenil, given in combination with CDP (5.0 mg/kg) antagonized the latter anxiolytic effect. In addition, in the presence of cues from potentially infanticidal males beta-CCM had anxiogenic activity, increasing latency to reach pups. The same CDP and beta-CCM doses were ineffective in the presence of cues from stressed females and in the absence of olfactory cues from conspecifics. CONCLUSIONS: This study provides behavioral and pharmacological validation of a new model of anxiety specifically designed for lactating females.

Animals↗

PubMed1992

Theta waves and behavioral manifestations of alertness and dreaming activity in the rat.

Electro-oscillographic recordings show that when rats wake up, behavioral manifestations such as head dorsal extension and snout and eye movements (which occur in this sequence), occasionally followed by brief ear and limb twitches, are preceded by and are simultaneous with theta waves (around 6.5 Hz in frequency) in neocortical areas 3 and 17 and in the hippocampus. Heart rate increases when the animal passes from synchronized sleep to relaxed wakefulness to exploratory behavior. During desynchronized sleep theta waves, similar to those found during alertness, usually precede and are simultaneous with rostrum and eye movements and brief ear and limb twitches. Heart rate also increases during dreaming activity. A high degree of coherence (near 1.0) was found among theta bursts in different hippocampal areas in both highly attentive alertness and dreaming. It is suggested that theta waves are related to attention as part of some kinds of behavior and of the process of dream shaping and expression, both characterized by consciousness.

Animals↗

PubMed2000

Measuring fear and anxiety in the marmoset (Callithrix penicillata) with a novel predator confrontation model: effects of diazepam.

This report describes a new experimental method for measuring fear and anxiety in Cerrado marmosets (Callithrix penicillata). In order to test the sensitivity of the behavioral parameters to an anxiolytic substance, the effects of the benzodiazepine diazepam on the anxiety measures were examined. The strategy was to use a naturally occurring stimulus known to elicit anxiety and fear in this species. A taxidermized predator (the wild cat Felis tigrina) was chosen as the stimulus to induce anxiety-related behaviors on the basis of a preceding study in which various stimuli were systematically compared in their effectiviness to induce fear responses. The apparatus consisted of three parallel arms of equal dimensions, joining two perpendicular arms at each end, thus comprising a figure eight-like or five-arm continuous rectangular maze. The wild-cat was placed outside of one corner of the maze's outer parallel arms. Each subject was submitted to six treatments given in random order: three drug sessions (diazepam 1, 2 and 3 mg/kg, i.m.), saline, sham (injection control), and a control session, involving neither manipulation nor injection. Subjects were placed into the back of the chamber, out of sight of the 'predator', 20 min after a treatment and given free access to the maze for 30 min. The behavioral repertoire was recorded via videocamera. The following behaviors were considered to be possible indices of emotionality relevant to exposure to the predator in the paradigm used: scratching, scent marking, exploration, frequency and time spent in each of 13 defined sections of the maze. Administration of diazepam induced a significant reduction in scratching and an increase in the time spent in the vicinity of the 'predator', as well as in the frequency of exploratory behaviors, indicative of an anxiolytic effect. Gender did not influence the effect of treatment. These results suggest that this new ethologically-based test may be a useful method for studying anxiety and fear-induced avoidance in non-human primates and for pre-clinical research on psychoactive drugs.

Animals↗

PubMed2004

Cognitive and motor development among small-for-gestational-age infants: impact of zinc supplementation, birth weight, and caregiving practices.

OBJECTIVE: Infants who are born small for gestational age (SGA) are at risk for developmental delays, which may be related to deficiencies in zinc, an essential trace metal, or to deficiencies in their ability to elicit caregiver responsiveness (functional isolation hypothesis). The objective of this study was to evaluate at 6 and 10 months of age the impact of a 9-month supplementation trial of 5 mg of zinc on the development and behavior of infants who were born SGA and to evaluate infants' ability to elicit responsive caregiver behavior. METHODS: A randomized, controlled trial of zinc supplementation was conducted among 200 infants in a low-income, urban community in Delhi, India. Infants were recruited when they were full term (>36 weeks) and SGA (birth weight <10th percentile weight-for-gestational age). Infants were randomized to receive daily supplements of a micronutrient mix (folate, iron, calcium, phosphorus, and riboflavin) with or without 5 mg of zinc sulfate. The supplement was administered by field workers daily from 30 days to 9 months of age. At 6 and 10 months, infant development and behavior were measured in a clinical setting using the Bayley Scales of Infant Development II. Caregiver responsiveness, observed on an Indian version of the Home Observation for Measurement of the Environment scale, was measured during a home visit at 10 months. During both the clinic and home visits, caregivers reported on their infant's temperament. RESULTS: There were no direct effects of zinc supplementation on the infants' development or behavior at either 6 or 10 months. In a subgroup analysis among the zinc-supplemented infants, lower birth weight infants were perceived to be more temperamentally difficult than higher weight infants; in the control group, birth weight was not associated with temperament. Heavier birth weight infants had better scores on all measures of development and behavior at 6 months and on changes in mental and motor development from 6 to 10 months, compared with lighter birth weight infants. Boys had better weight gain and higher scores on mental development and emotional regulation than girls. Infants who were from families of higher socioeconomic status (indexed by parental education, house size, and home ownership) had higher scores on mental development and orientation/engagement (exploratory behavior) than infants who were from families of lower socioeconomic status. In keeping with the functional isolation hypothesis, caregiver responsiveness was associated with infant irritability, controlling for socioeconomic status, gender, birth weight, and weight gain. Responsive mothers were more likely to perceive their infants to be temperamentally easy than less responsive mothers. CONCLUSION: Possible explanations for the lack of effects of zinc supplementation on infant development and behavior include 1) subtle effects of zinc supplementation that may not have been detected by the Bayley Scales, 2) interference with other nutritional deficiencies, or 3) no impact of zinc deficiency on infants' development and behavior. The link between birth weight and irritability among infants in the zinc supplementation group suggests that the response to zinc supplementation may differ by birth weight, with irritability occurring among the most vulnerable infants. Longer term follow-up studies among zinc-supplemented infants are needed to examine whether early supplementation leads to developmental or behavioral changes that have an impact on school-age performance. The relationship between infant irritability and low maternal responsiveness lends support to the functional isolation hypothesis and the importance of asking caregivers about infant temperament.

Birth Weight↗