1. Chapter 13 Learning and Memory

2. Types of Memory
Psychologists differentiate between learning and memory
Hebb (1949) differentiated between two types of memory:
Short-term memory: memory of events that have just occurred
Long-term memory: memory of events from times further back

3. Types of Memory (cont’d.)
Differences between STM and LTM
Short-term memory has a limited capacity; long-term memory does not
Short-term memory fades quickly without rehearsal; long-term memories persist
Memories from long-term memory can be stimulated with a cue/ hint; retrieval of memories lost from STM do not benefit from the presence of a cue

4. Types of Memory (cont’d.)
Researchers propose all information enters STM where the brain consolidates it into LTM
Later research has weakened the distinction between STM and LTM
Not all rehearsed short-term memories become long-term memories
Time needed for consolidation varies
Epinephrine and cortisol enhance consolidation of recent experiences by stimulating amygdala and hippocampus

5. Types of Memory (cont’d.)
Reconsolidated: memory is strengthened again by a process that requires protein synthesis
Working memory (WM)
Proposed by Baddeley & Hitch as an alternative to short-term memory
Emphasis on temporary storage of information to actively attend to it and work on it for a period of time
TED talk on WM:

6. Types of Memory (cont’d.)
Common test of working memory is the delayed response task
Requires responding to something you heard or saw a short while ago
Research points to the prefrontal cortex for the storage of this information
Brain may use extra calcium to increase readiness to respond to new signals

7. Types of Memory (cont’d.)
Older people often have impairments in working memory
Changes in the prefrontal cortex are assumed to be the cause
Declining activity of the prefrontal cortex in the elderly is associated with decreasing memory
Increased activity in this area indicates compensation for other regions in the brain

8. The Hippocampus Amnesia is the loss of memory
Studies on amnesia help to clarify the distinctions between and among different kinds of memories and their mechanisms
Different areas of the hippocampus are active during memory formation and retrieval
Damage results in amnesia

9. The Hippocampus (cont’d.)
H.M. is a famous case study in psychology who had his hippocampus removed to prevent epileptic seizures
Afterwards, H.M. had great difficulty forming new long-term memories
STM or working memory remained intact
Suggested that the hippocampus is vital for the formation of new long-term memories
Memento:

11. The Hippocampus (cont’d.)
H.M. showed massive anterograde amnesia after the surgery
Two major types of amnesia include:
Anterograde amnesia: the loss of the ability to form new memory after the brain damage
Retrograde amnesia: the loss of memory events prior to the occurrence of the brain damage

12. The Hippocampus (cont’d.)
H.M. had difficulty with episodic memory and declarative memory
Episodic memory: ability to recall single personal events
Declarative memory: Memory of facts & events
H.M.’s procedural memory remained intact
Procedural memory: ability to develop motor skills (remembering or learning how to do things)

14. The Hippocampus (cont’d.)
Patient H.M. also displayed greater “implicit” than “explicit” memory, as most patients with amnesia do
Explicit memory (declarative memory): deliberate recall of information that one recognizes as a memory
Implicit memory: the influence of recent experience on behavior without realizing one is using memory. Acquired and used unconsciously

15. The Hippocampus (cont’d.)
People with amnesia generally show this pattern:
Normal working memory
Difficulty forming new declarative memories
Some degree of retrograde amnesia
Better implicit than explicit memory
Nearly intact procedural memory

16. The Hippocampus (cont’d.)
Research of the function of the hippocampus suggests that it is:
Critical for declarative memory functioning (especially episodic)
Especially important for spatial memory
Especially important for contextual learning and binding

17. The Hippocampus (cont’d.)
Damage to the hippocampus also impairs abilities on spatial tasks such as:
Radial mazes: a subject must navigate a maze that has eight or more arms with a reinforcer at the end
Morris water maze task: a rat must swim through murky water to find a rest platform just underneath the surface

19. Video: https://www.youtube.com/watch?v=LrCzSIbvSN4

20. The Hippocampus (cont’d.)
Hippocampus may also be important for contextual learning
Remembering the detail and context of an event
Damage to the hippocampus impairs recent learning more than older learning
The more consolidated a memory becomes, the less it depends on the hippocampus

22. The Basal Ganglia
The hippocampus is not responsible for all memory, as gradual learning still takes place
Implicit learning or habit learning depends on the basal ganglia
The basal ganglia learns a strategy that leads to a correct response and develops a pattern
People with Parkinson’s disease have impairments of the basal ganglia and can’t develop implicit memory

24. The Basal Ganglia (cont’d.)
The “weather task” involves both declarative and implicit memory
“Normal” people learn it slowly under conditions of extreme distraction, similar to the learning of those with hippocampal damage
There is not a strict separation between basal ganglia tasks and hippocampal tasks
All tasks activate both areas, and one type of memory can shift to another

25. Other Types of Amnesia
Different kinds of brain damage result in different types of amnesia
Two common types of brain damage include:
Korsakoff’s syndrome
Alzheimer’s disease

26. Other Types of Amnesia (cont’d.)
Korsakoff’s syndrome: brain damage caused by prolonged thiamine (vitamin B1) deficiency
Impedes the ability of the brain to metabolize glucose
Leads to a loss of or shrinkage of neurons in the brain
Often due to chronic alcoholism
Symptoms include apathy, confusion, forgetting, and confabulation (taking guesses to fill in gaps in memory)

27. Other Types of Amnesia (cont’d.)
Alzheimer’s disease is associated with a gradually progressive loss of memory (especially declarative memory) often occurring in old age
Affects 50% of people over 85 and 5% of people 65-74
Early onset seems to be influenced by genes, but 99% of cases are late onset
About half of all patients with late onset have no known relative with the disease

29. Other Types of Amnesia (cont’d.)
The genes controlling early-onset Alzheimer’s disease cause the protein amyloid beta protein to accumulate both inside and outside neurons.
The net effect is to damage dendritic spines, decrease synaptic input, and decrease plasticity
An abnormal form of the tau protein

31. Other Types of Amnesia (cont’d.)
Accumulation of the amyloid beta and tau proteins results in:
Plaques: structures formed from degenerating neurons
Tangles: structures formed from degenerating structures within a neuronal body

33. Other Types of Amnesia (cont’d.)
At this point, no known drug is effective for treatment of Alzheimer’s disease, though research on some is underway
A common treatment involves enhancing acetylcholine activity, thus increasing arousal
Curcumin: an Indian spice that has been shown to inhibit amyloid-beta deposits and phosphate attachment to tau proteins
Animal research has been done and human research is just beginning