Chapter 4: Growth and Development

Question 1

Explain how a signal is sent in the nervous system

Answer 1

A signal is sent from one neuron to another.

An electrical signal is sent from the nucleus that is housed in the cell body and sends a signal to the axon which sends signals from the cell body to the terminal buttons. A neurotransmitter (a chemical signal) is then released from a terminal button and jumps the synapse and is received by a receptor cell in the dendrites of another cell and then it repeats.

Question 2

Babies have more neurons and synapses that adults

True or False

Answer 2

True, however it is still underdeveloped

Question 3

List the 4 brain lobes and their functions

Answer 3

Frontal lobe - involved in emotions, planning, cognitive functioning

Occipital - vision

Temporal - auditory, hearing, feelings

Parietal - touch, language

Question 4

What is a myelin sheath?

Answer 4

It is a fatty layer that surrounds the axon which increases the speed of signal transmission

Question 5

How many neurons does the adult brain consist of?

Answer 5

About 100 billion neurons

Question 6

What is the cerebral cortex?

Answer 6

The wrinkled surface of the brain that regulates many function. Specific regions (lobes) control specific functions.

It is divided into two hemispheres and is connected by the corpus callosum

Question 7

What is neurogenesis?

Answer 7

It is the production of neurons that begins at ~10 weeks post-conception and is almost complete by 28 weeks.

Neurons are formed at a rate of ~4000/sec for weeks and are formed in the neural tube.

They they move to their destinations and grow an axon and many dendrites

Question 8

Which neurons are myelinated first?

Answer 8

Begins with sensory neurons and ends with those in the cortex.

Various cortical areas become myelinated at different times in development.
Ex. the frontal lobe has a dramatic increase in myelination during adolescence

Question 9

When does synaptogensis occur?

Answer 9

Begins prenatally and move quickly toward birth and continues for a while. It peaks after the 1st birthday

Question 10

What is synaptic pruning and when does it occur?

Answer 10

Synaptic pruning is when synapses are eliminated to increase the efficiency of processing.

It occurs after a peak of synaptic growth but varies across brain areas:

• Pruning occurs in the visual cortex from 1-6
• Pruning occurs in the prefrontal area until adolescence

During peaks 100k synapses are pruned/sec and ~70% of synapses are pruned between 28 weeks and birth

Question 11

What does the term use or or lose it/neural darwinism refer to?

Answer 11

Synaptic pruning

Question 12

Synaptic pruning is more protractive than synaptogensis.

True or False

Answer 12

True - It occurs over a larger period of time

Question 13

Which synapses are pruned?

Answer 13

The ones that aren’t active/used

Question 14

Describe the A-not-B error

Answer 14

Children who have object permanence make this error after perseverating on a successful location.

If you have location A & B and you hide a toy under A twice and they retrieve it both times, but then mix it up and place it under B infants will still look under A

This occurs due to the underdevelopment of the prefrontal cortex

Question 15

What is an EEG and what type of evidence has been found for specialization?

Answer 15

An EEG is a non-invasive technique that detects electrical activity in the brain using electrodes

It has shown infants have a greater activation in the left side of the prefrontal area for positive emotions and more on the right side for negative ones

Question 16

What is the purpose of an fMRI and what type of evidence has been found for specialization? ?

Answer 16

an fMRI is an imaging study that uses magnetic fields to track blood flow through the brain

Typically done with children >6 as they can follow instructions and have found that certain brain regions are associated with processing written text in 7-13 yr olds

Question 17

Is specialization uniform across brain regions?

Answer 17

No. Timing aries for regions implicated in different aspects of processing and some regions are not fully specialized until adulthood.

Regions involved with basic sensory/perception are specialized earlier than regions involved in higher-order processing

Question 18

What are the two ways experience affects growth?

Answer 18

Experience-expectant growth: Normal wiring of the brain occurs as a result of experiences that humans who inhabit a species-typical environment will have

Ex. The brain expects input from the visual system to fine-tune its prewired circuitry

Experience-dependent growth: neural connections are created throughout life as a function of an individuals experience.

Ex. Specific effects (taking a new route home) or general effects (living in an enriched environment)

Question 19

What is the ‘best’ time for a brain injury and why?

Answer 19

Early brain injury is best because the brain isn’t fully specialized and plasticity allows the brain to reorganize

However, it depends on the sensitive period. If a child is born with cataracts and it is not fixed until older in life the occipital lobe may already be colonized by another brain function (i.e. hearing)

Question 20

The _____ is the part of the neuron that contains the biological machinery that keeps it alive.

Answer 20

Cell body

Question 21

During prenatal development and continuing into childhood and adolescence, axons and nerve cells acquire myeline, a fatty wrap that allows neurons to _____

Answer 21

transmit information more rapidly

Question 22

With development, brain systems become more specialized, in that smaller brain regions become activated and _______

Answer 22

more specific stimuli trigger brain activity

Question 23

In ______ growth, a developing brain depends upon environmental stimulation to fine-tune neural circuits

Answer 23

Experience-expectant

Question 24

A developing brain is more plastic than a mature brain, which means that following injury a developing brain ______

Answer 24

is more likely to recover