Lecture 6 Q &A Flashcards
What happened to patient RB?
Patient RB was a person who experienced a highly localized stroke. In a stroke, part of the brain loses blood flow, and cells often die as a result. In the case of Patient RB, a small section of his temporal lobe was affected. In particular, a section of his hippocampus, called CA1, was injured. As a result, patient RB lost the ability to form new memories (anterograde amnesia).
What kind of memory problems did patient RB have?
In the case study of Patient RB, he especially lost his declarative memories. He was not able to learn new facts. He could, however, learn the ability to perform new motor tasks
Describe the major input into the hippocampus?
The major input into the hippocampus is the perforant pathway, which projects into the dentate gyrus (DG), then the CA3 before entering the CA1. This projection is important for the creation of new memories.
The CA1 region receives external synaptic inputs from layer 3 of the entorhinal cortex. These cells then project to the subiculum before projecting out to the layers 4-6 of the entorhinal cortex.
In many ways, the damage to a part of his temporal lobe produced a similar set of symptoms as that of Patient HM.
What did patient RB teach us?
He taught us that the hippocampus itself is a critical part of the brain region for consolidation of new declarative memories.
Why did patient RB’s case strengthen what we know about the hippocampus?
This was because RB had a normal brain to begin with before the lesson was made. HM on the other hand had an brain that had undergone many seizures making it harder to study/argue.
What kind of amnesic syndrome did patient RB have?
50% Classic Amnesic Syndrome (50%)
What happened to patient N.A?
Sword fighting accident damaged his thalamus.
(Roomate was practicing and pierced his nose).
Medial temporal lobe = OKAY
Hippocampus = OKAY
Experienced HM-like amnesia
What is the thalamus involved in?
It is involved in consolidating declarative memory.
What is Koorsakoff’s Syndrome?
thalamus damage from alcoholism
Why is the retrosplenial cortex important?
It is part of the cingulate gyrus.
Damage to this region led to HM like memory.
Describe how positron emission tomography works.
Take a human and inject them with a substance (radioactive glucose) that travels everywhere including the brain
Photon detectors can see it
Glucose reaches the brain and emits positrons
Those positrons don’t travel very far before they run into an electron.
When a positron hits an electron then gamma rays are emitted.
Two rays travel 180 degrees away from each other
Annihilation is what allows gamma rays to be emitted.
You can manipulate the mapping of these gamma rays and thus use it for imaging and for things like locating a tumor.
What is an issue in PET scans?
All of our brains are a little different so they must be averaged/morphed onto a common template.
This results in an image of what was taking up glucose and what wasn’t.
What is the subtraction method?
To make sense of glucose uptake scan people while they are doing something and then scan them when they are not doing that activity.
Ex. Vision stimulation condition = eyes open
Control Condition = close your eyes
Voxel is the smallest unit you can detect.
Subtract how much glucose is going on in the simulation vs control condition.
This should subtract out = forming voxels when you see.
Validates that visual cortex is for seeing.
Describe the subsequent memory method.
1) Scan subjects while they learn lists of items to be remembered, record response to each item.
2) Delay (min, hours, days)
3) Test memory of items
4) Relate brain response during learning to subsequent memory success.
Glucose indicates how hard the brain is working.
Describe how an fmRi can be used to figure out what what the hippocampus does in response to being exposed to different words.
You can get a brain response to the hippocampus to all 20 words.
They will remember some words and not others.
You are in a position to average brain responses to all the words that they went on to remember.
Measure brain responses to what they remember and then what they forget.
The harder the hippocampus is working, the better you seem to retain your declarative knowledge.
