Psychology 1000 Split Brain October 2, 2012
Next Time: Genetics
Scan: P 109-116
How are the cortical areas organized?
What happens if these areas are damaged?
Is there a separate consciousness in each hemisphere?
Neuron A and Neuron B synapse with Neuron C. You are measuring the electrical activity in Neuron C.
When Neuron A fires, an action potential is generated in Neuron C. But when both A and B are
stimulated, there is no action potential observed in C. How can you explain this?
a) The neurotransmitter in B is Ach
b) Neuron A is disinhibited
c) Neuron B generates an IPSP
d) Neuron B depolarizes the post-synaptic membrane
e) Measurement error
1. Topographic Representation
Mapping on the brain’s surface that corresponds to the body and everything you could
possibly move on the motor cortex
2. Contralateral Control
There is opposite side control in each of the hemispheres
Left hemisphere controls right side of the body and vice versa
3. Functional Assignment of Space
There isn’t an equal distribution of space -> some parts of the body get more cortical tissue
The more functionally important an area is, the more space it gets in the motor cortex
How do we get this information
Scan the intact brain and get information about what’s going on
Evidence from brain damage
Direct stimulation of the cortex
Take an x-ray of the brain and enhance areas of the brain with a dye
Helps to see if someone had a stroke or if there’s a blood clot in the brain
Doesn’t show detailed structure or anything about function, just shows where the blood vessels
are and whether or not they’ve been damaged
X-rays from 360 degree rotation Psychology 1000 Split Brain October 2, 2012
Ventricles are spaces in the cortical mass that allow for things like the flow of vessels, cerebral
spinal fluids to flow
They are important, but they shouldn’t be huge.
MRI or fMRI
Magnetic Resonance Imaging
Exposed to a really strong magnetic field
When the brain is exposed to the magnetic field, there will be a shift in electron orbits so we can
get very good structural information; clear imaging
Almost as good as anatomical dissection in terms of liability to pull the information out
fMRI combines with functionality of PET scans, so that you can see which areas are picking up
For detailed work and important things, do an fMRI
Positron emission topography
Injects radioactive glucose
Finds which neurons pick up the radioactive glucose