Learning & Memory Flashcards
key functions of hippocampus
- Learning
- Memory formation and retrieval
- Site of adult neurogenesis
learning vs. memory
- Learning:
- Acquisition of knowledge or skills through experience
- The storage process; creation of memories
- Memory:
- Information that is stored (ex. Memory of your grandma)
- The structure that stores the information (e.g. the strength of synapses in a particular part of the brain)
Patient HM
- Suffered intractable epilepsy, suffering severe seizures that were resistant to the then available anticonvulsive treatments
- Electroencephalogram indicated that the origin of the seizures was the hippocampus of the medial temporal lobe
- Surgical management considered and undertaken
Results of Patient HM’s surgery
- Successful in reducing seizures
- IQ increased
Able to learn new motor tasks with practice - Memory problems emerged – severe anterograde amnesia (unable to form new memories)
Morris Water Maze - influence of hippocampal lesion
Hippocampal lesion causes increased path length (over control group and other types of lesions) -> significant impairments in learning and memory
Rat stress, fear, and learning experiment: basics
- rats put into maze or open field
- fear/anxiety measured (time spent frozen/unmoving, and defecation rate)
- Categorized rats based on consistency in response as either High anxiety (HA) rats or Low anxiety (LA) rats
Rat stress, fear, and learning experiment: Morris water maze
- HA rats took longer to find platform that LA rats
- HA rats circled on the outside more than LA rats (who ventured into the middle)
Rat stress, fear, and learning experiment: plasma corticosterone levels and mineraloid receptors
- In HA rats, higher levels of plasma corticosterone
- In HA rats, fewer MR receptors, more free-floating glucocorticoids that could bind to GR receptors
Barnes maze
- measures Spatial Learning and Memory
- Round table with holes around edges, only 1 hole leads to escape box, rat placed in middle of table
advantages/disadvantages of Morris vs. Barnes
- Morris is much more stressful – rats don’t usually go in water
- Barnes assesses perimeter, which rats naturally go to
- Morris has more variables to control/monitor (ie. Water temperature)
Memory Retention and Extinction: stromatopod/crustacean example
- Males and females share nest cavity for ~2 days before breeding; intruders to area are repelled
- After mating, male leaves in search of a new mate, while females guard their offspring for 4 weeks, after which the brood/offspring leave
- Question: will males remember their mate?
- YES! For 2 weeks, they can recognize and show less aggression to their former mate
Memory vs. perseveration - what is perseveration?
- Repetition of a response despite the absence/cessation of the
stimulus. - Example: Foraging for food
2 ways to learn
- genetics/fixed responses
- learning/experiential responses
model for evolution of learning: when would natural selection favour each type of learning? (cost-benefit perspective)
- Under conditions where environment rarely changes AND conditions where environment constantly changes, genetics is more beneficial than learning
- In the middle of the 2 extremes, learning is most beneficial
assumptions of the model for evolution of learning (when each type of learning is favoured)
- Cost (even very small) associated with learning (ex. Energy output)
- The ability to learn is a trait that has an underlying genetic basis
