Chapter 4: Growth and Development Flashcards
Explain how a signal is sent in the nervous system
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.
Babies have more neurons and synapses that adults
True or False
True, however it is still underdeveloped
List the 4 brain lobes and their functions
Frontal lobe - involved in emotions, planning, cognitive functioning
Occipital - vision
Temporal - auditory, hearing, feelings
Parietal - touch, language
What is a myelin sheath?
It is a fatty layer that surrounds the axon which increases the speed of signal transmission
How many neurons does the adult brain consist of?
About 100 billion neurons
What is the cerebral cortex?
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
What is neurogenesis?
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
Which neurons are myelinated first?
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
When does synaptogensis occur?
Begins prenatally and move quickly toward birth and continues for a while. It peaks after the 1st birthday
What is synaptic pruning and when does it occur?
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
What does the term use or or lose it/neural darwinism refer to?
Synaptic pruning
Synaptic pruning is more protractive than synaptogensis.
True or False
True - It occurs over a larger period of time
Which synapses are pruned?
The ones that aren’t active/used
Describe the A-not-B error
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
What is an EEG and what type of evidence has been found for specialization?
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
What is the purpose of an fMRI and what type of evidence has been found for specialization? ?
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
Is specialization uniform across brain regions?
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
What are the two ways experience affects growth?
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)
What is the ‘best’ time for a brain injury and why?
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)
The _____ is the part of the neuron that contains the biological machinery that keeps it alive.
Cell body
During prenatal development and continuing into childhood and adolescence, axons and nerve cells acquire myeline, a fatty wrap that allows neurons to _____
transmit information more rapidly
With development, brain systems become more specialized, in that smaller brain regions become activated and _______
more specific stimuli trigger brain activity
In ______ growth, a developing brain depends upon environmental stimulation to fine-tune neural circuits
Experience-expectant
A developing brain is more plastic than a mature brain, which means that following injury a developing brain ______
is more likely to recover
