13 terms

Psych 469 Final Exam People


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Wrote the Neurobiology of Stress and Development. This work highlighted the positive impact of the Stress Response System on adaptation and health, as well as the impact of overactivation of the SRS. In addition this work goes over the basic biology of the SAM and the HPA Axis within the Stress Response System, and the different individual responses to stress.
Involved in Gene - Environment Contributions to the Development of Infant Vagal Reactivity: The Interaction of Dopamine and Maternal Sensitivity.
• She studied the dopamine receptor genes DRD2 and DRD4 and maternal sensitivity as predictors of infant respiratory sinus arrhythmia (RSA) and RSA changes as a reaction to stressors. Findings indicate that having a high resting RSA (vagal tone) is implicated with having a good temperament, good attention, sociability, and a healthy response to stimuli in infancy, while a decrease in the ability to suppress RSA and withdraw the vagal brake (variability in heart rate when one breathes -- increasing HR during inhalation) during periods of stress. Mutations of dopaminergic receptors, DRD2 and DRD4 are associated with impulsivity and low inhibition and aggression. The findings of this study indicate a three way interaction between genes, environment, and age, in that by 12 months, genes (the mutations or lack of mutations of the Dopaminergic Receptors a child has), the environment (low or high maternal care) and the age (12 month, vs. 6 months when maternal care has not had enough time to impact the RSA suppression system) all impact the regulation of heart rate and the RSA change in periods of stress.
Meaney, Aiken
Wrote the Epigenetics and the Biological Definition of Gene · Environment Interactions. The findings of the paper indicate that early handling causes an upregulation of glucocorticoid (GC) receptors in hippocampus that augments the capacity to regulate stress. This progress in the physiological aspect of handling effects on the adult organization of the HPA Axis showed that GC receptors in the hippocampus facilitate negative feedback of HPA Axis activity. Such that, the more GC receptors an individual has, the better the individual is able to regulate their Stress Response System via the HPA Axis (reducing the likelihood of over activation).
Individual differences in maternal care are transmitted from mother to female offspring through their effect on the differential expression (as constrained by relative methylation) of the estrogen receptor alpha (ER) in the medial preoptic area of the hypothalamus (MPOA). Champagne 2011 discusses the evolutionary/ecological implications of epigenetic control of the genome. Offspring of mothers who provide high maternal care are more selective about mates and reproduce less frequently, while offspring of low maternal care mothers mature more quickly and have more offspring. This is the idea of R and K selection. R Selection =Reproduction; sexually mature quickly, reproduce with many offspring, usually short lifespans - exist in environments that are dangerous where it is advantageous to pass on genetic code to many offspring and create as many mutations as possible that may make the species more successful at survival. Like rats, insects, etc. K-Selection - "Care" Selection, mothers provide high levels of maternal care to few offspring, which mature late and in turn have few children. Primates, large animals are involved with this - putting energy into few offspring to ensure their survival in the environment.
JLG: Author of the polyvagal theory
Based on Freud's concept of childhood impacting development and behavior, Levine set on an experiment to test handling effects in rats. Levine had three groups of rat pups -- one group that was handled and received foot shocks, one group that was handled but received no foot shocks, and a control group that received no handling. Pups that had been handled (those that received and did not receive foot shocks) received more maternal care than those that were not. As adults, these handled pups better regulated their HPA Axis and stress response system. Handled pups were overall less fearful and weighed more and had smaller adrenal gland weights and reached peak Cortisol levels faster than the unhandled pups and reached baseline cortisol levels faster than the unhandled pups. These results were unexpected, as Levine figured the pups who had been handled (and stressed) would be more fearful in adulthood.
Liu et al.
Disentangled handling effects from the impact of the level of maternal care on the ability to regulate the HPA Axis and the Stress Response System. He took unhandled pups of low maternal care mothers and compared them to unhandled pups of high maternal care mothers and found that in adulthood, when injected with cortisol, pups of high maternal care mothers were better able to regulate their stress response system and had a higher density of GC Receptors than their comparison.
probabilistic epigenesis (co-action model/bidirectionality)
Postulated that the reason the rat pups that had been handled developed less responsivity/better regulation to stress was because of hypothermia, rather than stress as Levine originally hypothesized. The rat pups Levine was handling in his experiment were very young and hairless -- meaning that removal from the warmth of their mother into a foreign, cold environment, meant significant drops in body temperature. Shaeffer postulated that this was the biological cause of the development of a more regulated stress response.
Proposed that the initial environment a pup is born into (how much maternal care the pup receives within the first few days of life) was used as a proxy to mirror the environment they would live in their whole life. Low-licking mothers are oftentimes providing low maternal care because they do not have the time/resources to provide substantial care to their young because of the scarcity of food, disease, etc. Thus it is extrapolated that low maternal care mothers live in poor environments. In this way, it is environmentally beneficial for a pup born to a low maternal care mother (and, by extension, a dangerous and stressful environment), to poorly/regularly activate the HPA Axis of the SRS System to remain vigilant to danger.
Von Baer
embryonic development 1) From simple to complex; simpler structures appear first 2) From less to more differentiated 3) Development generates a hierarchy of systems: cells, tissues, organs, cognitive, and behavioral systems 4) As it proceeds, development generates for itself new contextual factors that further direct its course
Emphasized that maternal care was a joint process between pup and mother, rather than mother alone. Pups provide ultrasonic cries that biologically triggers maternal care in mothers. Maternal care is based off of the pup's ability to cope with stress, the pup's stress, and the mother's willingness/availability to provide maternal care (based on mother's hormonal state and experience as a mother).
Wrote Epigenetics and the Biological Definition of Gene X Environmental Interactions. Describes the physical basis in which the environment an individual lives in can structurally alter the individual's DNA. Focuses on the change in the regulation of the stress response system based on the level of maternal care.