Memory (oct 21/23) Split Brain (23)

Question 1

Name the two Primary types of amnesia

Answer 1

1. retrograde amnesia
   - is more common for recent memories than older ones
   - memory loss of before the injuries
2. anterograde amnesia
   - memory loss of memories before the injuries.

Question 2

what can cause amnesia?

Answer 2

seizures, tumors, stroke, anything that can injure your brain.

Question 3

Identify patient HM’s removed brain structure

Answer 3

bilateral medial temporal lobectomy. Removal of the hippocampus, amygdala, and nearby cortex (highly connected to hippocampus)

Question 4

Describe HM’s performance on short and long term memory tasks.

Answer 4

HM had a normal working memory (he could list numbers in a normal digit span) however when they changed the study to be the same numbers plus a new one every time he could only get to 6 digits. Which means that between 6-7 digits we must switch to long-term memory which HM must not have.

HM has implicit, non-declarative long-term memory = improvement overtime, intact procedural memory.

Question 5

What are the 3 forms of memory

Answer 5

Sensory, short (or working), long term.

Question 6

How is the information lost from each form of memory?

Answer 6

1. sensory - information is unattended too.
2. short term memory - information is unrehersed.
3. long term - time may lose so memory

Question 7

What are the 2 types of sensory memory?

Answer 7

• iconic memory (visual) - 1 sec
• echoic memory (auditory) -5-10 sec

Question 8

How do long term memories become durable and permanent?

Answer 8

Consolidaition!

At the Sensory memory the memory must be attended too…

At Short Term memory the memory must be rehearsed

At the long term point it must be retrieved.

Many researchers believe that the process of consolidation is mediated by the hippocampus and that the individual memories are stored in the cerebral cortex and thats how retrograde amnesia patients (or HM) have their childhood memories. This could be explained why long term memories are less emotional and more story like.

Question 9

Identify the divisions of long-term memory and which behavioural tasks are they linked too?

Answer 9

1. Implicit, non-declarative (cerebellum and basal ganglia)
   - Improvement over time = intact procedural memory.

a) procedural memory - motor cognitive skills

b) priming - enhanced identification of objects or words

c) learning through classical conditioning.

2. Explicit, declarative (effortfle hippocampus, frontal temporal lobes)
   - Lack of memory for the training sessions = deficit of episodic memory.

a) semantic memory - facts and general knowledge (celebrity)
b) episodic memory - personally experienced events.

Question 10

What is priming? how did the amnesic patients preform with recall after priming.

Answer 10

Priming is giving a hint to enhance the memory. After being primed (even without specific memory of being told a word they were able to identify it.

Question 11

What is the example of classical conditioning that we saw with amnesic patient

Answer 11

after given a handshake with a pin prick the patient did not specifically remember that they were pricked by the specific person but they did remember that “sometimes pins are apart of handshakes” and refused to shake hands.

Question 12

Name the role of the hippocampus in memory consolidation

Answer 12

The hippocampus is used the form longterm memories, but to consolidate them the memories go from the hippocampus to the cerebral cortex to make the “story” like childhood memories that are very long term.

Question 13

Identify a difference between the memory performance of patient HM and patient KC

Answer 13

HM lacked episodic memory and showed impaired semantic memory.

KC experienced diffuse damage including bilateral hippocampal damage. He could not form new episodic memories however he was able to make new semantic memories.

Question 14

Explain what Korskakoff syndrome is

Answer 14

• Result of brain damage due to thiamine (B1) deficiency
• often, but not always, due to heavy alcohol consumption
• often, but not always, preceded by Wernicke’s encephalopathy - an acute brain reaction to lack of thiamine
• confusion, abnormal eye movements, hypothermia, coordination problems, coma

Question 15

What are the damaged structures in Korsakoff syndrome.

Answer 15

• Medical diencphalic structures (thalamus and hypothalamus
• Diffuse damage to cortex, hippocampus, cerebellum.

Question 16

What is the treatment and recovery rate for Korsakoff syndrome

Answer 16

Treatment:
- Thiamine supplements + nutrition
- Address alcohol use is prevalent

Recovery:
- 25% recover fully
- 50% some recovery
- 25% unchanged

Question 17

What are the memory deficits associated with koskakoff syndrome.

Answer 17

• severe anterograde amnesia, mild retrograde amnesia - limited to explicit memories.
• often confabulate to make up for memory loss.

Question 18

Describe the surgical procedure that was performed on the split-brain patient cohort

Answer 18

They removed the corpus callosum because they saw that epileptic discharge can spread from one hemisphere to the other via the corpus callosum.

Question 19

Describe the procedure used to provide visual information to only one hemisphere at a time.

Answer 19

If we spread apart to seperate objects of sight enough the right eye will retain the left informtion and the left eye will retain the right information. So if we show this to a split brain person (since they cannot connect the 2 sides of the occipital lobe info) we can see which side of the brain is correlated with language, movements etc.

Question 20

Predict the performance (spoken, written/drawn by each hand) of a split brain patient when each hemisphere is tested on a simple word or image.

Answer 20

Right side of the brain (left stimulus):
If the right side of the occipital lobe sees “car” it would not be able to say “car” because language is processed on the left side of the brain. But if we get the patient to draw with their left hand they could draw the car cueing the word.

Left side of the brain (right stimulus):
They would be able to say “car” as this is where language is and they could draw a car with their right hand.

Question 21

What is anomia?

Answer 21

if a split brained patient does not see the item and is given the item in their left hand, the right hemisphere will not be able to describe or say what the item is just like sight.

Question 22

Compare the abilities of patients with callosal agenesis to adult split brain patients.

Answer 22

• Can be complete or partial
• Language skills and IQ fairly normal (unless there are other abnormalities)
• surprisingly minimal disconnection compared to adult split brain patients.
• plasticity in children allows alternative cross-hemispheric pathways to be reinforced (the anterior commissure)
• if the task is extremely complex with lots of visuals and shapes, and is fast there may be some impairments seen.