April 28, 2021
PSY 340 Brain and Behavior
Class 33: The Hippocampus and Striatum (Outline)
Prevalence Data on KS and Alzheimer's Disease
United States population in 2020 was 331 million people
Korsakoff's Syndrome. I was asked in class about the prevalence of Korsakoff's Syndrome, a fact that I did not readily know other than the fact it was rare. Arts et al. (2017) note that there is very little data about the prevalence and what data there is show a range of values:
- 48 per 100,000 in The Hague, The Netherlands (1987 study) ===> equivalent to ca. 159K total cases in US in 2020
- 30 per 100,000 in North-Holland, The Netherlands (1992 study)
- 5 per 100,000 per year in Glasgow, Scotland (1990-1995) ====> equivalent to ca. 16.5K total cases in US in 2020
- No other prevalence rates appear to be available
Normal Aging ---15-20%---> Mild Cognitive Impairment (MCI) ---10-20% ---> AD
In 2020 there were roughly 55 million Americans 65 years of age or older
- 6.2 million Americans 65 years old+ in 2021 have AD
- 11.5% of Americans 65 years old+ in 2021 have AD
- Projected 12.7 million wlll have AD by 2050
IV. The Hippocampus
Amnesia = memory loss
H.M., whose real name we now know was Henry Gustav Molaison, died in Windsor Locks, CT on December 2, 2008.
What kind of brain functioning does H.M. show?
- No effect on intellect & language functions. I.Q. slightly higher in the years immediately after operation.
- Personality was relatively the same except for "emotional placidity" (= no complaints; no requests even for food)
- Good short-term memory, i.e., for new items up to about 5-10 minutes after the experience.
Massive anterograde amnesia (loss of memories of new events since brain damage)
Moderate retrograde amnesia (loss of memories of events before brain damage).Some small amount of new learning of declarative memories
- Prompt: "Elvis" • HM's response: "Presley"
- Prompt: "Fidel" • HM's response: "Castro"
- Prompt: "Martin Luther" • HM's response: "King"
- severe impairment in episodic (personal) memories.
- Intact procedural memory, i.e., learning how to do something new.
Explicit memory: recall of information which one knows is in memory
Implicit memory: influence of recent experience on behavior even though one doesn't recognize memory is being used.
- H.M. showed poor new explicit memory, but nearly normal implicit memory.
What does the Hippocampus do? Theories of Hippocampal Functioning
1. Declarative Explicit Memory
2. Spatial Memory
- London taxi cab drivers have "the Knowledge"
- Humans with damage to the hippocampus do poorly on tests of spatial memory
- Bird species with good spatial memory
- Human "grid & place cell" navigation system: Nobel Prize 2014
- Place cells (hippocampus): mental map of place; spatial memory
- Grid cells (entorhinal cortext): map of place; orientation of head; distance between self & object
3. Context: Configural Learning & Binding
V. Striatum: Implicit or Habit Learning (Where Skills and Habits Meet)
Basal Ganglia = striatum (i.e., putamen and caudate nucleus) plus the globus pallidus, substantia nigra, and subthalamic nuclei.
The striatum appears to be mostly involved in what can be termed "reinforcement-level learning" - that is,
- Gradual learning over multiple trials
- Learning habits and skills
- Learning requires prompt feedback (= reward or punishment is clear)
- Learning is implicit, that is, what is learned is not put into words, but into actions
- If the striatum is damaged, the ability to learn new skills or habits is impaired and previously learned skills/habits are often impaired as well