Psychology of Infancy Defining development, prenatal development, brain development D. Messinger, Ph.D. Questions (single essay format) Define development. Argue for why you believe development does or does not have an endpoint. Describe genetic and experiential factors in brain development referring to experience expectant and experience dependent factors. Give examples of how prenatal sensory experience impacts sensory development. Describe similarities between the brain development of the postnatal child and differences in the brains of adult humans and macaque monkeys? Is it is all over after age 3? What are some basic patterns of synaptic and brain development in infancy? How they are influenced by experience? What can go wrong in this pattern? Provide examples from Nelson. What is the take-home message of Thursday's reading, The Seductive Allure of Behavioral Epigenetics? Development defined Development defined Individual change that is, normative, nonreversible, relatively stable, and sequential. Normative process Everyone’s doing it Non-reversible Reorganization of the entire person Relatively stable You can’t go back, Sequential change Crawl before you walk Examples Is development Increasing functionality in all things? Loss of perceptual acuity in non-native languages between 6 & 12 months Old-age Is development Headed toward a goal? Development has normative outcomes, but time goes forward prior events cause subsequent events not the opposite What does Thompson (2001, p. 21) mean? “A drive to development is inborn, propelling the human infant toward learning and mastery.” Three models In class assignment: What would a cross-tab of the transactional model look like? What does individual development look like? Individuals Group Prenatal brain development Overview of brain growth Subcortical areas responsible for reflexes develop first E.g. spinal cord Followed by cortical areas in a specific progression What is most human develops last Most but not all neurons present at birth Synapses develop Myelin develops Cortical Expansion Similar patterns of cortical expansion between infants and adults as between macaque monkeys and adults “The pattern of human evolutionary expansion is remarkably similar to the pattern of human postnatal expansion” (Hill et al., 2010) Bell Postnatal cortical surface expansion. Hill J et al. PNAS 2010;107:13135-13140 ©2010 by National Academy of Sciences Fig. 1. Postnatal cortical surface expansion. Maps of postnatal cortical surface expansion on the standard mesh average inflated term infant surfaces for both hemispheres, shown in lateral (A), medial (B), dorsal (C), and ventral (D) views. The absolute expansion scale indicates how many times larger the surface area of a given region is in adulthood relative to that region’s area at term. The relative expansion scale indicates the difference in proportion of total surface area at term birth and adulthood. Comparison of evolutionary and postnatal cortical surface expansion. (A) Map of regional evolutionary cortical expansion between an adult macaque and the average human adult PALS-B12 atlas (right hemisphere only). Evolution expansion scale indicates how many times larger the surface area is in humans relative to the corresponding area in the macaque. (B) Map of human postnatal cortical expansion (combined left and right hemispheres) for comparison (detailed in Fig. 1 legend). (C) Correlation map comparing postnatal to evolutionary cortical surface expansion. Different regions, different rates Regions responsible for lower cognitive functioning develop more rapidly Regions responsible for higher cognitive functioning develop more slowly They may have selection pressure to remain immature: To facilitate the development of regions more crucial for early surival To limit overall brain size at birth by focusing on areas most necessary for early survival and keeping the head small (birth canal) Bell Writing assignment What processes do Tierney and Nelson discuss under the concept of Early Stages of Brain Development? Define three of these process. Overview: http://www.youtube.com/watch?v=YXTA0lUBZW4 1:20-2:19 Increasing differentiation of areas of cortex Infant is born during height of brain development Tertiary sulci develop from 1 month before to 12 months after birth Four levels of brain development From Nelson, 1999 Creation of a tube Synapses are connections between neurons Neural migration Many elements of initial neural migration specified genetically By 20 weeks gestation, 100 billion neurons! 50,000 – 500,000 neurons per minute Neurons follow path of glial cells outward from ventricles To form 6 layers of cortex Proliferation & migration of neurons General pattern of brain development genetically specified By 20 weeks, most neurons present 3rd - 16th prenatal week most crucial At 8 weeks, head is half of fetus But specific connections depend on generic growth processes and sensory-motor stimulation Trillions of connections still forming Trimming of these connections is developmental task Neural development: Synaptogensis Once in place, synapses are overproduced somewhat haphazardly 1 year old has 150% more synapses than adult These are pruned (diminish) during development Repetition of sensory-motor patterns create more specific set of experience dependent synaptic linkages Time lapse sequences of radial migration (also known as glial guidance) and somal translocation neurite outgrowthhttp://www.youtube. com/watch?v=n_9YTeEHp1E& NR=1 Neuron migration Typical and Atypical http://www.youtube.com/watc h?v=GBIa8G3gBH0&feature=r elated Increase in complexity of neural connections Like a growing forest How do the correct synapses form? 15,000 synapses for every cortical neuron 1.8 million per second in first 2 years! Cerebral cortex triples in thickness in 1st year Sensory and motor neurons must extend to correct brain are and form correct synapses This quantity of information cannot be genetically micro-managed Two types of experience in brain development Experienceexpectant Experience dependent Experience-expectant “How common early experiences provide essential catalysts for normal brain development” Early visual stimulation, hearing, exposure to language, coordinating vision and movement, “The developing brain “expects” and requires these typical human experiences, and relies on them as a component of its growth.” Experience-dependent “How individual experience fosters new brain growth and refines existing brain structures” “Can be unique to an individual” Reading Singing, music Neural Darwinism (Edelman) Use it or lose it What is not used, is pruned What is used, develops stronger connections Organism & environment are system that shapes brain Brain development is guided by environment Brain enables behavior which shapes brain Synaptic development is not teleological The fetus as constructing its own development Fetal behavior impacts physical development In chicks prevented from moving, cartilage turns to bone Fetal sensory experience impacts sensory development Mice whose tongues were anesthetized had malformed cleft palates Prenatal sensory experience impacts sensory development Hearing typically develops before sight Rats, ducklings, and quail chicks exposed to visual stimulation prenatally before they normally would lose hearing ability at birth Normal sensory development contingent on extra-fetal environment Differences in the timing of augmented prenatal stimulation led to different patterns of subsequent auditory and visual responsiveness following hatching. When augmented tactile and vestibular stimulation coincided with the onset of auditory function (Days 9-14), embryos subsequently failed to learn a species-typical maternal call prior to hatching. No effect on normal visual responsiveness to species-typical maternal cues when exposure to tactile and vestibular stimulation coincided with the emergence of visual function (Days 14-19) When exposure took place after the onset of visual functioning (Days 17-22), chicks displayed enhanced responsiveness to the same maternal visual cues. Honeycutt, H. & R. Lickliter (2003). Developmental Psychobiology 43: 71-81. The influence of prenatal tactile and vestibular stimulation and visual responsiveness in bobwhite quail: A matter of timing “Promoting early brain development”? Re-discovery of importance of early experience “How brain connections grow and change as a result of stimuli from the environment. How early stress can be harmful to the developing brain. Principle of "use it or lose it" Seven ways to support brain development: http://www.pitc.org/ “Considerable misunderstanding of early brain development occurs when neurons and synapses are considered independently of the development of thinking, feeling, and relating to others.” Thompson, 2001, p. 29 Is it all over after 3? Is the course of development set in infancy? Early experience is important But, with some exceptions, human beings remain open to the positive effects of additional experience The same is true for the impact of experience on brain development How important is it to ‘stimulate your child’s brain’? Implications for Policy and Programs Sensitive periods & Neuroplasticity Financial payback Early identification and intervention Fernandez Abecedarian Intervention Project • Children who participated in the early intervention program had higher cognitive test scores from the toddler years to age 21. Academic achievement in reading and math was higher from the primary grades through young adulthood. Intervention children completed more years of education more likely to attend a four-year college. Intervention children were older when their first child was born. Mothers whose children participated in the program achieved higher educational and employment status than mothers whose children were not in the program. Results especially pronounced for teen mothers. Enhanced language development appears to have been instrumental in raising cognitive test scores. Fernandez Implications for practice It is important to provide a safe, warm, supportive, stimulating environment for infants But its never too late to improve developmental outcome for an individual At any point, current conditions are as important as past conditions Baby media No flashcards… http://www.psychologicalscience.org/i ndex.php/news/releases/do-babieslearn-vocabulary-from-baby-mediastudy-says-no.html Brain Overgrowth in the First Year of Life in Autism The clinical onset of autism appears to be preceded by 2 phases of brain growth abnormality: a reduced head size at birth and a sudden and excessive increase in head size between 1 to 2 months and 6 to 14 months. Abnormally accelerated rate of growth may serve as an early warning signal of risk for autism Courchesne, Carper, Akshoomoff, (2003) Why overgrowth? Rate of head circumference growth as a function of autism diagnosis and history of autistic regression. Webb, Sara Jane; Nalty, Theresa; Munson, Jeff; Brock, Catherine; Abbott, Robert; Dawson, Geraldine Journal of Child Neurology, Vol 22(10), Oct 2007, 11821190. doi: 10.1177/0883073807306263 Birth Process Midwifery – the first profession Prenatal to Postnatal Preparation for Birth -Braxton Hicks contractions -Hormonal activities (e.g. progesterone -> estrogen = muscle activity) Stages of Birth 1. 2. 3. From womb to birth canal. Longest stage, uterine contractions (enables mother’s cervix to expand). From birth canal to outside. Pushing. Afterbirth. Delivery of the placenta Survival after Birth -Baby breathes on its own. -Change of blood circulation (oxygenation now occurs from the lungs not the placenta Romero Human birth – cephalo-pelvic proportionality Are human beings evolving? How might the rise in the rate of delivery by c-section be related to evolution? Final project ideas Prenatal maternal stress Prenatal infection Prenatal behavior Impact on outcomes (after birth) Embryology: www.ehd.org Human birth – a social process "In nonhuman primates, the fetus usually emerges with its face toward that of its mother. She may then reach down and pull it up toward her along the normal flexion of its body. "In humans, however … the close equivalence of cephalopelvic dimensions has resulted in … infant being born facing away from its mother. In this position, the use of her own hands to assist delivery before the shoulders have emerged could result in pulling the infant against the normal flexion of its body, again with the risk of injury particularly to the nerves of the neck." Wenda R. Trevathan, Human Birth, (New York: Aldine de Gruyter, 1987), p. 89-92 Human birth – graphic content More medical, ‘produced’ video http://video.google.com/videoplay?docid=7170052415220169972&q=birth+videos Just video of birth evtv.com NPR segment on birth process Prenatal development is usually divided into three main periods. Zygote - covers the first two weeks after conception ends when the zygote implants into the wall of the mother's uterus. Embryo from two to eight weeks following conception the major organs and bodily systems form Fetus from eight weeks after conception until birth grows tremendously in size and weight. Messinger Zygotic cell differentiation Messinger From zygote to embryo Messinger The question The zygote grows through cell division Mitosis - One for one copying of all 23 chromosomes All cells contain the same genetic information in their nuclei But qualitatively different types of cells develop in different parts of the body How does this occur? Messinger General processes yield specific outcomes Cells clump together as a sphere This changes the extra-cellular environment of cells on the inside and outside of the sphere Differences in environment impact cell’s genetic make-up to activate different proteins Messinger Genes in Environment Environmental factors influence development from the start Cells are environments The uterus is an environment The fetus participates in actively constructing its own development it is not passively constructed Messinger What do you think? Stem cell debate Cloning Assistive reproduction technology Messinger Additional readings Plomin, et al. The genetic basis of complex human behaviors. Plomin, R., & Rutter, M. (1998). Child development, molecular genetics, and what to do with genes once they are found. Child Development, 69(4), 1223-1242. Rutter. M. (in press . Nature, nurture, and development: From evangelism through science towards policy and practice. Child Development. Collins, W. A., Maccoby, E. E., Steinberg, L., Hetherington, E. M., & Bornstein, M. H. (2000). Contemporary research on parenting: The case for nature and nurture. American Psychologist, 55(2), 218-232. Sleigh, M. J., Columbus, R. F., & Lickliter, R. (1998). Intersensory experience and early perceptual development: Postnatal experience with multimodal maternal cues affects intersensory responsiveness in Bobwhite Quail Chicks. Developmental Psychology,Messinger 34(2), 215-223.