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Psychology-chap 12.docx

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University of Toronto Scarborough
John Bassili

Psychology- Chapter 12 Lecture notes Brain Wiring and Plasticity Life begins with conception, when a single cell, made from sperm and egg forms a zygote. This divides multiple times and everything that follows came from that single cell. From this point a neural tube forms, the bottom which become the spinal cord and top the brain. The brain is not wired at conception and connections between nerve cells are made in the womb. So many highly complicated connections but the question becomes how? The video shows the incredible fest of development. How is it that each neuron knows where to go and how to behave? There are trillions of these interconnections are they all equally important? There are 10000 nerve cells in one piece of brain the size of a grain of rice. Even a babys brain is extremely complex. There are trillions of connections and nerve cells. But how does the brain know how to connect itself and behave the way it does. 500000 neurons are formed every minute Most of the cells in the body die and are replaced, i.e. skin cells ( 90pound of skin lost in a life time) but not neural cells. The ones you are born with, you will also die with Brain wires itself by following a highly specified genetic blueprint, connections follow specific rules Brain wiring is all specified genetically, like wired telephones between Boston and New York If connections are being used they are strengthened and if not they are weakened. Use it or lose it mentality In a premature birth- the process of brain wiring is only partly over, a huge amount of wiring needs to be done in the nursery Can nature trump nurture? Experiment with the ferret: the brain of a ferret was restructured, visual input to eye wired to hearing (auditory cortex) The question they wanted to answer was: could hearing come to have the same circuits or connections as vision If NO- then nature is important, If YES- then nurture is important Regular ferret, pinwheel colour scheme observed Experiment ferret, pinwheel colour scheme also observed but not organized Conclusions: Yes, it is true that the environment shapes the brain, but it cannot completely change genetic destiny. The experiment with ferrets tells us that the brain has a remarkable amount of plasticity Remark: Gabrielle Gibbons: able to stand but not able to talk. Women are more bilateral it terms of the language as we saw in the language section so maybe she will be able to gain that back. Neural plasticity will be very important in determining how she progresses. Plasticity in terms of the brain is basically the fact that through tapping in we can rely of different pathways in the brain in order to do things, if one other way is obstructed or something. But again it is not a simple matter APGAR Birth is an extremely delicate process Scale used by health care professionals to quickly assess newborns overall health condition APGAR stands for: activity (muscle tone), pulse, grimace (reflex, irritability), appearance (skin colour) and respiration Babies are tested 1 minute and 5 minutes after birth Each category on the scale can receive a maximum of 2 points, for a grand total of 10 points Most infants score between 7-10 on the APGAR which is good. Score or 4-6 is considered fair condition and 0-3 is considered non responsive and the baby needs immediate life saving care. Newborn Reflexes Reflexes are inborn automatic responses, natures toolkit to help an infant adapt Some of them include breathing, swallowing, and sucking; these all have survival value Others like Moro, grasping and stepping are considered leftover from evolutionary heritage Survival reflexes become voluntary but the primitive reflexes disappear after the first year Some reflexes are predominantly related to nourishment of the infant i.e. child starts sucking on doctors finger, or just about anything that comes near its mouth Stroke the corner of babys mouth and you can see the rotating reflex; child turns head in direction of stroke, for finding food Moro or startle(spreading of arms when let go) reflex disappears at about 5 months of age, if Moro is not there at birth or reappears after the 5 month period, then there may be damage to central nervous system Swimming reflex occurs when you place a baby over water while still holding them; they start to paddle like theyre swimming Reflexes are used to determine normal brain activity. The absence or persistence beyond normal times and the reappearance later in life is a hint at significant neurological problems Bubinski reflex: bottom of foot is stroked, big toe flexes forward toward top of foot and other toes fan out Normal in children under 2 years of age, after that time if it is still there it indicates damage to the nerve paths connecting the spinal cord and the brain Imitation, Habituation, Early Perception Newborns are able to imitate a number of adult facial gestures. Aiden only a week old can stick his tongue out and imitate the looks his mother gives him Older infants reproduce behaviours on cue Habituation to a repeated stimulus also provides evidence for early learning. Habituation is getting bored with something and then paying attention to a new or novel stimulus A toy initially interests the child but it is shown repeatedly until she habituates or becomes disinterested and stops responding. When a new or novel toy is presented the child responds or dishabituates and she notices something else. Infants are well equipped to face the world, they are actually well developed before birth, and they turn their heads in the direction of sounds. Babies are very responsive to familiar voices like mom and dad. Newborns are especially sensitive to high pitched tones Vision is the least developed of the senses, babies are very near sighted, which is well suited for looking into the eyes of the caregiver holding or feeding them Newborns have clear visual preferences, they will gaze longer at bold patterns with strong contrast, it is also more interesting for them to look at human faces Smell: Babys sense of smell is very discriminating; they like and dont like the odours of certain things. They like fruity smells and hate the smell of vin
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