Neuroscience II Flashcards
What is the neuraxis?
Nervous system axis
True or false: the neuraxis goes straight up and down from the top of your neck to your toes
False
It curves at your head
What does “dorsal” refer to?
The back of the neuraxis
What does “ventral” refer to?
The front of the neuraxis
What does “rostral” refer to?
The top of the neuraxis
What does “caudal” refer to?
The bottom of the neuraxis
What do you call regions that are more central of the brain?
Medial
What do you call regions towards the outside of the brain?
Lateral
Where is the rostral ventral medial medulla located?
Towards the top (rostral)
In front of the neuraxis (ventral)
Towards midline of the brain (medial)
Describe the case study of Phineas Gage
Gage was a foreman of a railway construction crew. He was very kind and respected by his fellow crew-mates
One day, he was in an accident which resulted in the blasting of a three foot iron rod completely thru the top of his skull
Tho he recovered, his personality changed. He was now selfish, angry, etc.
Shows that the brain has specialized structures for complex behaviour
What is a limitation of case studies like Phineas Gage’s?
Rarely isolated to specific structures; makes a more difficult task of assigning impaired function to specific brain areas
How can you overcome the limitations presented by case studies (i.e. the ones in Phineas Gage’s)?
By studying specific brain lesions in animal models
Researcher removes a defined brain region and observes the result on behaviour
How accurate are lesion studies?
Depends on the precision of the lesion
Even so, bc brain is highly connected, a variety of behaviours can be affected by a single lesion
What is another approach to studying the brain, besides lesion studies?
Targeted electrical stimulation:
Electrically stimulate an area of the brain and observe the result on behaviour to build an anatomical map related to function
Which method of studying the brain did Dr. Wilder Penfield use as he performed brain surgery to treat patients with epileptic seizures?
Targeted electrical stimulation
Describe Wilder Penfield’s “Montreal Procedure”
A patient undergoing surgery would be under local anaesthetic and fully conscious (since the brain itself does not have pain receptors). They worked with Penfield to locate and remove the scarred tissue
Used a thin, carrying a small electrical charge to stimulate the cortex —> individual neurons fire —> patient gives observations –> accurately map perceptual processes to brain regions
How would Penfield know if an area of the visual cortex was stimulated [from his “Montreal Procedure”]?
If the patient reported seeing flashes of light when that area was stimulated
Describe the single cell recording procedure
Small electrode inserted into nervous tissue of a live animal model with its tip held just outside the cell body of an individual neuron.
Neural activity recorded while animal performs a task or a stimulus is presented. Pattern of firing reveals a PARTICULAR/individual neuron’s functional role
How did Hubel and Wiesel use single cell recordings in cats?
Presented cats with specific visual stimuli while recording from single cells in the visual cortex. Individ cell types were identified that responded to specific categories of visual stimuli
What do scientists use to study large-scale structure and function of brain regions?
Structural neuroimaging:
- CT
- MRI
Functional neuroimaging:
- PET
- fMRI
- EEG
What does CT stand for?
Computed tomography
What happens during a CT scan?
Series of xray slices of the brain are taken and pieced together to produce a quick and inexpensive pic of the brain
In what instance would you use a CT scan?
Diagnose brain injuries
What’s a limitation of CT scans?
Low res; difficult to examine fine brain anatomy
What does MRI stand for?
Magnetic Resonance Imaging
What happens during a MRI scan?
Powerful magnetic fields are generated and align the hydrogen atoms found throughout the brain; can localize tissue very precisely
What does PET stand for?
Positron Emission Tomography
What happens during a PET scan?
Radioactive tracer of glucose or oxygen is inserted into the bloodstream. Molecules make it to the brain and are used in metabolic processes, which are detected by the PET scan.
More active areas will use more metabolic resources –> image of brain’s relative pattern of activity can be constructed
In what instance would you use a PET scan?
To learn how brain function relates to cognitive tasks such as language and memory (cognitive scientists use this a lot)
What’s a disadvantage of PET scans?
Req a radioactive tracer to be injected (invasive procedure)
How does fMRI work?
Measures the blood oxygen dependent signal; measures the relative use of oxygen throughout the brain
More active areas will use more oxygen/metabolic resources
Why are fMRIs preferred over PET?
Less invasive
What’s a limitation of fMRIs?
Provides a rough image of brain activation. Oxygen use spikes a few seconds later than the spikes of activity in the brain
DON’T USE if interested in precise timing of brain activation and function
What does EEG stand for?
Electroencephalogram
How does EEG work?
Electrical activity of brain recorded thru scalp by cap of sensitive electrodes; provides rough pic provided by families of neurons
How can you make the EEG more informative?
In event related potential experiment, specific stimulus presented repeatedly while EEG is recording. Stimulus has a small and consistent reading that can be averaged out after many trials. This balances the noise usually made by EEG.
Even after balancing the noise in EEGs, the ERP signals are still difficult to interpret. How do they usually have to interpret most signals? Provide an example
Number of signals serve as markers for diff neural processes
Ex. N170 wave corresponds to face processing
What does the hindbrain consist of?
Medulla
Pons
Reticular formation
Cerebellum
The structures in the hindbrain are responsible for the regulation of vital bodily functions. Why is this not surprising?
Evolutionarily the oldest parts of the brain; found in nearly ever vertebrate species