Chapter 3/4

Question 1

adaptive reflexes in infancy

Answer 1

• palmar reflex
• sucking reflex
• rooting reflex
• stepping reflex
• plantar reflex

Question 2

palmar reflex

Answer 2

• occurs when something is placed in the palm of an infant’s hand and the infant quickly wraps their fingers around the object
• forces them to practice grasping in order to prepare them to pick of objects

Question 3

sucking reflex

Answer 3

• occurs when something touches the roof of an infant’s mouth
• 2 aspects: expression (to express milk from a nipple by pressing it between their tongue and the roof of their mouth) and milking (moving tongue from areola to nipple to coax milk from breast)

Question 4

rooting reflex

Answer 4

• occurs when anything strokes an infant’s cheek or corner of their mouth -> infant will turn their head towards the side that was touched
• helps them search for breast b/c they don’t have neck muscles
• rooting indicates hunger

Question 5

stepping reflex

Answer 5

• occurs when the soles of an infant’s feet touch a flat surface -> they will life their legs as if they are marching or stepping
• tries to trigger areas in the brain related to walking

Question 6

plantar reflex

Answer 6

• infant’s tendency to curl their toes down or away from their shin
• exercises ability to use feet for grasping, but this goes away because adults don’t reinforce it

Question 7

what is the purpose of adaptive reflexes in general?

Answer 7

they enable infants to perform crucial motor skills which they otherwise wouldn’t be able to do due to insufficient brain development at birth

Question 8

neuronal proliferation

Answer 8

• rapid production of neurons during the 10th-18th weeks of prenatal development
• because of this, most fetuses have produced all of their neurons by the 28th week of prenatal development

Question 9

why can’t babies perform so many motor skills, even if they have all their neurons?

Answer 9

• neurons aren’t tightly packed together -> have synapses/gaps between each other
• neuron structure must further develop in order to communicate across the gaps

Question 10

when do neurons consist of cell bodies only?

Answer 10

when they’re travelling from the neuron-manufacturing site

Question 11

dendrites and axons

Answer 11

• allow neurons to form connections with other neurons
• allow neurons to communicate with other neurons
• are stimulation-dependent

Question 12

dendrites

Answer 12

bring info from other neurons to the cell body (to receive info from other neurons)

Question 13

axons

Answer 13

take info away from the cell body to other neurons (to send info to other neurons)

Question 14

synaptogenesis

Answer 14

although a few neurons have formed synapses in pre-natal period, this mass production of synapses (dendrite and axon growth) occurs during infancy and toddlerhood

Question 15

synaptic pruning

Answer 15

• the retraction/elimination of unused synapses

- synapses are activity dependent (need stimulation to survive) - if we don’t use it, we lose it

Question 16

why are so many synaptic connections eliminated/pruned?

Answer 16

• inactivity (use it or lose it)

- initially the neuron produces a huge over-abundance of synaptic connections

Question 17

advantage of synaptic pruning

Answer 17

• enables neurons to communicate with each other more efficiently (operational efficiency)
• this efficiency is accomplished due to greater specificity (automaticity) in synaptic connections

Question 18

neuroplasticity

Answer 18

brain’s ability to reorganize/regenerate synapses from repeated stimulation/activity (helpful after a stroke, for example)

Question 19

glial cells

Answer 19

• responsible for a lot of brain development in newborns
• responsible for myelination of axons
• different from neurons

Question 20

myelination

Answer 20

• improves speed/efficiency of message transfer between neurons
• most rapid during the first 2 years after birth
• myelin = fatty substance

Question 21

what 2 major things happen in our brain after birth?

Answer 21

• synaptogenesis (increase in axons and dendrites)

- myelination of axons (increase in number of glial cells)

Question 22

involuntary/voluntary transition period

Answer 22

• involuntary = controlled by reflexes
• voluntary = adequate brain development to control movement
• during this period, it’s common to notice a decline in some of an infant’s motor skills
• ex. grasping skills - infants can grasp objects at 0-1 month, then from 2-3 months they can only swipe them, them at 4-6 months they can voluntarily grab objects

Question 23

3 stages of prenatal development

Answer 23

• germinal
• embryonic
• fetal

Question 24

germinal stage

Answer 24

• 1-2 weeks

- conception and implantation in uterine wall

Question 25

embryonic stage

Answer 25

• 3-8 weeks

- organogenesis (creating organ structure)

Question 26

fetal stage

Answer 26

• 9+ weeks

- cell differentiation and growth/development