Chapter 4-6 Flashcards
Functions of cerebrospinal fluid?
- cushions brain
- removes waste
- supports neurogenesis
- contains immune-related molecules
- controls neurotransmitter precursors
What structures comprise the brain stem?
medulla, tectum, tegmentum, pons
Describe how the blood-brain barrier is different in the medulla
In the area postrema, the blood-brain barrier is more porous than the rest of the brain
Describe the effects of cerebellar agensis
Only mild/moderate decifits in balance and motor control
What are the four cranial nerves in the medulla?
Glossopharyngeal, vagus, accessory, hypoglossal
Describe how Wilder Penfield provided evidence for localization of function?
By stimulating the somatosensory and motor cortexes while the patient was awake he was able to map parts of the body onto the brain. The amount of tissue associated with parts of the body was proportionate to the amount of sensation experienced in that body part
Name the neurotransmitter systems and what processes they are involved in
Cholinergic - learning, memory, arousal
Dopaminergic - motor control, reward processing, motivation, addition
Noradrenergic - arousal, sustained attention
Serotonergic - arousal, mood, sleep
Describe the preparation process of the sample in visible light transmission microscopy
- sample is fixed in place using formaldehyde
- sample is dehydrated using acetone
- sample is hardened using paraffin
- sample is sliced into very thin pieces using a microtome
- certain structures are stained to observe them more closely
Describe the two types of electron microscopy
TEM - electrons are fired through the sample and the ones that make it through strike a phosphorus plate and the others bounce back. Heavy metals are used to stain the sample which decreases the number of electrons that can pass through
SEM - electrons are moved back and forth across sample to see how many are backscattered
Advantages and disadvantages of CAT scan
A - can be used to create 3D reconstruction, don’t take very long
D - requires radiation, requires contrast dyes
Advantages and disadvantages of MRI
A - no radiation, no contrast dyes
D - takes a long time, expensive
Describe how Diffusion Tensor Imaging (DTI) works and its purpose
Tracks the movement of water through the 3 axon bundles in the brain (corona radiata, cingulum, inferior longitudinal faciculus). Used to determine anatomical connectivity between structures across the brain
Describe how fMRI uses blood flow to measure structural changes in brain
Brain structures that are more active require more O2 from blood and so blood vessels in the capillaries in these regions dilate to allow more deoxyhemoglobin to pass into brain. This process decreases the amount of deoxyhemoglobin which increases the MRI signal.
Describe why PET uses glucose
Because glucose is the brain’s main source of energy for neural activity, PET involves injecting version of glucose to see where it is used in the brain. This will show where brain activity is occuring.
Describe why fNIRS is more ideal than PET or fMRI
Because it is less expensive and portable
Describe which imaging techniques measure brain activity indirectly vs directly
fMRI, PET, fNIRS vs EEG, MEG
List 3 ways proteins can be introduced to the body in optogenetics
Transgenic animals, viral delivery, gene gun
Describe one practical application of tDCS
Helping stroke victims regain function of their limbs on their affected side
Name one disorder that EBS may be used to treat
Major Depression
What are all the ways optogenetics can be used?
At the synapse, neuron, local circuit, intralayer, whole brain, behaviour
Which imaging technique can be used to create a “virtual patient”?
TMS/rTMS
Which layer in the neural induction stage of development eventually forms the neural plate?
Ectoderm
Where do all stem cells originate from?
Ventricular zone
Describe how growth cones move throughout brain
They are repelled by certain substances and attracted to by others which causes them to move
Describe how neurons move through tangential migration
Higher concentrations of chemotropic cues in extracellular fluid facilitate the growth of cones, and areas of the cone in lower concentrations will die off. The neuron continues to grow in the direction where there is a higher concentration of chemotrophic cues.
Describe the process of synaptic pruning and how it relates to learning
Synapses that are active release neurotrophic factors when they release neurotransmitters. Inactive synapses do not release neurotrophic factors and so microglia prune back these synapses. When we learn something new, a synapse is created but if you don’t try and maintain this knowledge, the synapse will slowly be removed. By using repeated and spaced practice you strengthen synapses and can also form connections to other synapses which enhances your learning.
How can the myelination stage provide insight into why adolescence and young adult brains are still developing?
The frontal lobes are the last part of the brain to become fully myelinated. This explains why it teenagers are more impulsive and like to take risks; the part of the brain responsible for forward-thinking, inhibition, and executive control is not yet developed
Describe the rate and timing of neurogenesis
Initially, more neurons than necessary are created and the number peaks around 28 weeks after conception. After this there is a systematic decline in the amount of neurons that occurs throughout the rest of life
What are the effects of alcohol on a developing fetus?
Poor executive control/inhibition, impaired memory/learning, attention deficits, smaller cerebral cortex (smaller inferior parietal lobe, superior temporal region, ventral frontal region), wider sulci, less white matter, smaller/missing corpus callosum
What does “dose-dependent effects” mean in regards to alcohol and fetal development
This means that the more alcohol a mother consumes while pregnant, the more damage she is doing to her unborn fetus. There is NO KNOWN SAFE LEVEL of alcohol at this time.
Explain the experiment with rats in regards to environmental complexity and its implications for human development
Rats were either placed in a control or an enriched condition where they had friends, toys, and room to run. The rats in the enriched condition had more dendritic spines and greater dendritic spine density compared to the control condition. This provides evidence that children should be provided with rich and stimulating environments, especially room to be physically active, to help increase their number and strength of neural pathways.
Explain the experiment with rats in regards to environmental complexity and its implications for human development
Rats were either placed in a control or an enriched condition where they had friends, toys, and room to run. The rats in the enriched condition had more dendritic spines and greater dendritic spine density compared to the control condition. This provides evidence that children should be provided with rich and stimulating environments, especially room to be physically active, to help increase the number and strength of neural pathways in their brain
What is the role of the choroid plexus?
To secrete cerebrospinal fluid
What are the effects of hydrocephalus and how is it treated?
Too much CSF builds up in the ventricles and widens them, causing brain tissue to be compressed and blood flow to be restricted. It is treated by placing a shunt in the ventricles to drain the fluid and alleviate the pressure in the brain.
Identify the brain divisions and associated ventricle
Telencephalon - lateral ventricle
Diencephalon - third ventricle
Mesencephalon - cerebral aqueduct
Metencephalon and Myelincephalon - fourth ventricle
Describe the structure of the meninges
The layer closest to the skull is the dura matter, then the arachnoid membrane, then the pia mater. The fluid-filled space between the arachnoid and the pia mater is called the subarachnoid space.
Describe the structure and function of the circle of Willis
The left/right carotid and left/right vertebral arteries run up the neck and join together to form the circle of Willis. The function is to provide blood flow between the anterior and posterior parts of the brain and to serve as a safety mechanism against stroke because if one of the blood vessels is thinned or blocked. Blood can flow bidirectionally because of the pressure and shape of the structure.
Describe what the following terms mean in the brain: dorsal, ventral, rostral, caudal
Dorsal - towards the top
Ventral - towards the bottom
Rostral - towards the front
Caudal - towards the back
Describe the function of the sympathetic, parasympathetic, and enteric nervous systems
Sympathetic - to prepare the body for fight/flight
Parasympathetic - to prepare the body to rest/digest
Enteric - controls gastrointestional behaviour
What is the major difference between the brain of a human and the brain of a chimpanzee?
Human neurons proliferate longer
What two areas do we make new neurons in throughout our life?
Basal ganglia and hippocampus
Consumption of alcohol affects what receptors?
Inhibits receptors for glutamate and enhances receptors for GABA
What were the results of the weasel study?
The temporal lobe was rewired to receive input from the optic nerve and it produces visual responses.
What was the most important factor in the enriched condition in the rat experiment?
Physical activity
What were the findings of how blind people since birth process Braille?
There was activation in the occipital lobe during touch sensation but they couldn’t identify the Braille letters when this area of the brain was inhibited whereas sighted people could. Blind people also use the occipital lobe to respond to auditory stimuli, especially language
What is happening when musicians get muscle cramps?
It occurs because the representation of the hand has increased in the somatosensory cortex because of repeated practice, but now the areas for each fingers may overlap and so musicians cannot move the fingers independently anymore
What is the most significant reason for adolescent impulsivity?
The brain’s response to rewards and anticipation of rewards increases strongly during these years
What is the purpose of using an EEG to create evoked potentials?
It can be used to gather responses from people that cannot communicate verbally
What was one of the earliest discoveries about the nervous system?
Afferent dorsal roots carry sensory information and efferent ventral roots carry motor information
Explain the difference between the pre and postganglionic fibres in the parasympathetic nervous system compared to the sympathetic nervous system
Parasympathetic - preganglionic fibres are long, postganglionic fibres are short
Sympathetic - preganglionic fibres are short, postganglionic fibres are long
What are the three structures in the Basal Ganglia that form the corpus striatum?
Caudate nucleus, putamen, global pallidus
Explain what the BOLD signal is
In fMRI imaging, the Blood Oxygen Level Dependent signal identifies the areas and degree of activation in the brain
What is the spatial and temporal resolution of fMRI?
Good spatial, poor temporal
Which cells other than glial cells help produce neurons in proliferation and neurogenesis?
Basal progenitors
