Week 3 Developmental Science Lecture Notes An overview of Prenatal Development -Big Picture: look at nature/nurture debate at the starting point of development (arguably the most “nature”).-What we will see, however, is that development is from the beginning!-Overall Goal: To develop a deep understanding of nature AND nurture (the “interactionist” perspective)-Special emphasis: Neural development -to understand if a behavior is “innate”, must know something about the development of the brain Modern Interactionism-Conclusions form the Human Genome Project:-“There are two fallacies to be avoided [as we look toward the future]: determinism, the idea that all characteristics of the person are ‘hard-wired’ by the genome; and reductionism, the view that with complete knowledge of the human genome sequence, it is only a matter of time before our understanding of gene functions and interactions will provide a complete causal description of human variability. The real challenge of human biology… will lie ahead as we seek to explain how our minds have come to organize thoughts sufficiently well to investigate our own existence.”-from p. 1348 of Venter et al. (2001). The sequence of the human genome, Science, 291, p. 1304-1351-nature an nurture shouldn’t be something that we consider -we need to avoid some tendency once we sequence the genome we can know which effects the genes- but the idea of determinism and reductionism- can’t just rely on genes-Characteristics that are innate or genetic Clicker question: “innate” characteristics?a. Eye Color b. Hair color c. Height d. Dimples -Shenk reading pg. 16- way to think about genes is that they are not hardwired- they will have different tags and be upregulated or down regulated due to environmental factors -Genes as an auditory mixer- can dial up or dial down gene expression -too easy to just fall back on the genetic explanation-have more discoveries of importance of genes for disorders-> doesn’t mean that gene for x means that the present of x- too simplistic to think of genes causing something The Developmental Challenge -Saying something is innate/genetic is TOO EASY -We need to be critical thinkers and not be seduced by simplistic “explanations”-Let’s take a careful look at what really happens in early development -Key idea: it’s more about Developmental Process and less about a genetic program-Individual Differences!- can start with differences in fetal environment (e.g. teratogens, experience)-Environment in utero has more effect on development than when after born- exposure to stress hormones during development have changes inthe brains reaction to stress results to adult mood disorders Studying prenatal development -Epigenesis: emergence of new structures and functions during development -Embryology: the study of prenatal development- structure, effects on, etc…-Importance of animal models!-Phylogenetic continuity-how closely related genetic make-up and how long ago you have a common ancestor with something-can see very similar continuity and stages of development- Human, Monkey, Pig, Chicken, Salamanders- look similar at limbic stage -All limbs and bodies are there- embryo is a very small human- everything is preformed -Embryology- researchers found that there are not performed structures, but those that develop and unfold depend on chemical interactions in utero-Epigenesis- new structures can form b/c of the developmental process- interaction b/w cells of embryo and the uterus -2 faced cat- not b/c of a gene, but b/c of the developmental process that leads to the development of the face -Not a genetic mutant- developmental process that has gone off the tracks Stages of prenatal development-Human development -The stages of prenatal development- horizontal bars show the development of different systems or structures- some start before other, but there is a lot of overlap-Exposure to some visual stimuli might have effect on hearing- overlap of developmental structure -Prenatal problems- exposure to chemical, stress hormones- how you are exposed and how long, effects when the structures are formed -In the embryo the stem cells are not differentiated How do we build a baby?-The simplistic solution: genetic program -The challenge: every cell has the same genetic material…how do cells “know” what they are?-The solution: the environment tells them…-3 layers of cells form-Different locations of these layers causes different cell types to form (digestive system; heart, muscles, bones; spinal cord, brain, skin)-Cells communicate with their neighbors via chemical signals that turn genes on/off-the location of the cells relative to other cells is one of the steps to differentiation -Chemical signals and genetic make-up and down regulation through the biochemical signals b/w cells Prenatal Developmental Processes -A key point: it’s not all about nature/genes-The prenatal cellular environment matters just as much…-Dramatic example: Teratogens -environmental agents that cause damage during prenatal development -damage can be physical or psychological -Smoking- environmental pollutants- teratogens- monster producing -structural development, but also behavioral problems -Alcohol:-fetal alcohol syndrome: -mental retardation, -poor attention-slow physical growth-fetal alcohol effects:-some but not all abnormalities-alcohol interferes with cell duplication, migration of neural tube, deprives fetus of oxygen-Cigarette Smoking:-low birth weight-possible miscarriage or infant death-less attentive to sounds and more muscle tension-nicotine: constricts blood vessels, reducing transfer of blood & other nutrients-Illegal Drugs:cocaine & heroin:-prematurity-low birth weight-physical defects-breathing difficulties-often die near birth -AND, addicted at birth so crying and tough to care for-Low birth weight- problems with developing normally, also has effects later on- latter behavioral problems Overview thus far…-Summary 1: Prenatal development is not just about genes and biology -cellular environment matters just as much -However, must also consider fetal activity- another aspect of nature/nurture interaction -swallowing amniotic fluid and sucking thumb, prepares the baby to drink milk Prenatal Environment: Sensory experience and behavior matters too!-Touch:-Grasping, sucking, rubbing, bumping walls of uterus-> feedback is important -Taste:-Swallows amniotic fluid -Fetus has a sweet tooth-> not only