~Class 15 - Brain Development Flashcards
What part of Michels brain did Dr’s remove, and why?
Doctors removed the left hemisphere of Michael’s brain to treat severe epilepsy.
The left hemisphere is centrally involved in speech, language, and attention.
Over time, his right hemisphere reorganized & took over functions
When is the brain most plastic?
Infancy and Adolesence
Is the brain plastic in adulthood?
Yes, just not as much as in Infancy and Adolesence
Periods of heightened brain plasticity provide ___ as well as ___.
positive opportunities // vulnerabilities
What are the features of Developmental Plasticity?
- “Exuberant” growth of new brain circuits & synaptic connections
- Predisposed to be modified
- Brain development is easily influenced by a wide range of experiences
What are features of Adult Plasticity?
- Relatively minor modification of existing brain circuits/connections
- Predisposed to stability
- For enduring changes, you need to pay more attention/give special meaning to experiences
Brain development begins in earnest during the ___ period of ___ development.
embryonic // prenatal
The embryonic period starts at the point of ___, so around ___ weeks from the start of the pregnancy, and lasts till ___ weeks gestation.
implantation // 2 // 8
The major event that’s occurring during the Embryonic period is the development of the ___.
Neural Tube
The way the neural Tube forms is that it starts out as the ___, a ___ structure, which then curves up around itself creating a tube-shape.
Neural Plate // flat
When is the embryo most susceptible to Teratogens?
During the Embryonic period
The Neural Tube forms the ___ and ___.
Brain // Central Nervous System (CNS)
When neural tube defects occur toward the bottom of the neural tube, the most likely outcome is ___, which typically involves weakness or full paralysis of the ___.
spina bifida // lower limbs,
When the neural tube does not close up where the brain would be forming tends to result in ___, which occurs when major parts of the developing fetuses brain just don’t develop. The fetus is unlikely to survive, they may reach full-term, but cannot survive beyond the first few hours or days.
Anencephaly
The ___ is important for things like regulating bodily functions.
brain stem (hindbrain and midbrain)
What are the 4 process that occur during the fetal period of prenatal development (9+ weeks)?
- Neurogenesis
- Neuronal Migration
- Neuronal Differentiation
- Synaptogenesis
What is Neurogenesis?
The formation of new neurons in the brain (starts in 5th week)
What is Neuronal Migration?
Neurons move from the centre of the neural tube outward
What is Neuronal Differentiation?
Neurons are genetically pre-programmed to go to specific areas of the brain
What is Synaptogenesis?
The formation of synaptic connections between neurons
What is Synaptic Pruning?
Eliminating unused neural pathways
As babies, we make more ___ and form more connections than we’ll need, and over time, unneeded ones are ___.
neurons // pruned away
What is Myelination?
A process in which the axon is coated with layers of fatty insulation (myelin sheath)
What are Glial Cells?
Some Glial cells produce a waxy fatty substance called Myelin, which will wrap itself around the Axon of a neuron, which serves a couple of functions that make neural communication more efficient.
A Myelinated cell can propagate a signal down the axon ___ than an unmyelinated axon.
faster
Myelin, as it wraps around the axon, allows electrical signals to jump from one point to another, between the Myelin Sheaths in little gaps called ___.
Nodes of Ranvier
Myelination tends to start in the ___ and ___ parts of the brain, like the brainstem and cerebellum.
lower // deeper
Myelination in the frontal lobe continues until ___.
25
During childhood, there is gradual and ongoing change in all regions of the brain, in ___.
localized spurts
Brain development in childhood involves specialization of ___ and ___ of different regions
neural structures // integration
Rapid synaptogenesis/grey matter peaks at age ___, then Synaptic pruning takes over
10
White matter (myelin) increases through to ___.
early adulthood
In the first year there is a large increase in synaptic density in the ___ cortex, which peaks relatively early before tapering off and declining in the childhood years.
visual
There is a bunch of Synaptogenesis in the ___ cortex early on, but the peak extends into year 3 before it more gradually begins to decline.
auditory
At age ___years, grey matter in sensory and motor regions thin.
5-8
At age ___year, grey matter in parietal and temporal regions thin
6-11
At ages ___, grey matter in the frontal lobe gradually thins.
11 to adulthood
What reorganization happens from ages 12-18 in the brain?
- Gradual refinement of neural networks
- Development of the “social brain” (puberty hormones ↑sensitivity to oxytocin)
- Development of subcortical (limbic) regions, including reward network
- Maturation of the prefrontal cortex
What part of the brain becomes hypersensitive to emotional experiences between ages 12-18?
The Amygdala
What occurs to the Corpus Callosum between the ages of 12-18?
During adolescence, the nerve fibres that connect the hemispheres are getting thicker, and that allows the adolescent to process info more efficiently between the two hemispheres (Corpus Callosum)
What is the dual systems model of adolescent brain development and risk-taking?
The Prefrontal Cortex (which controls self-regulation) isn’t working fast enough to do its job to say STOP to the Limbic System, which is sensitive to reward.
The ___ are the sensitive gas pedal, and the slow-developing ___ are the bad brakes.
Limbic regions // Prefrontal Cortex
