Biological (Relationship between Brain and Behavior) Studies

Question 1

Maguire

Answer 1

Aim:
- demonstrate how cognitive processes may lead to neuroplasticity in the hippocampus

Procedure:
- 16 London male taxi drivers who had all passed “Knowledge” test and had license for 1.5 years
- compared MRI scans of taxi drivers to those who did not drive taxis
- used voxel-based morphometry and pixel counting to determine if there was significant differences in neural density (grey matter)

Results and Conclusions:
- pixel counting revealed that posterior hippocampi of taxi drivers was significantly larger, and anterior was significantly smaller
- vbm showed volume of hippocampus correlated with time spent as taxi driver
- supports localization of function since posterior hippocampi appears involved when using previously learned spatial information and anterior in encoding new environments

Strengths and Limitations:
- no cause-and-effect since it was a quasi experiment
- small sample size
- double-blind design avoided researcher bias
- MRI does NOT reduce ecological validity

Question 2

Draganski

Answer 2

Aim:
- observe if learning a new skill, juggling, would have an impact on brain

Procedure:
- 24 participants divided into two groups: juggling and control
- both scanned in MRI at beginning, 3 months, and 6 months
- used VBM to determine differences in neural density in jugglers vs. non-jugglers

Results and Conclusions:
- initial scan showed no significant differences between conditions
- after mastery of juggling, MRI showed increase in grey matter than control group, however this decreased after time spent not practicing
- supports ideas of neural pruning and neuroplasticity (use it or lose it)

Strengths and Limitations:
- cause-and-effect
- small sample size
- lacks internal validity since could not control for home environments for majority of study

Question 3

Troster and Beatty

Answer 3

Aim:
- determine the effect of Acetylcholine on memory measures, including creation and retrieval

Procedure:
- 13 healthy adult men
- 3 separate sessions at least 48 hours apart receiving either saline, 0.5mg of scopolamine, or 0.8mg of scopolamine
- subjects and experimenters blind to condition, but knew because of side effects of drug
- given multiple memory tests:
free recall - read a list of words and asked to recall immediately and then after a long delay (STM to LTM)
new map - given fictitious map and asked to locate cities on a blank map (STM to LTM)
remote memory - shown images of famous faces and asked to recognize them (LTM retrieval)

Results and Conclusions:
- scopolamine injection caused inhibition of encoding new memories
- no significant effect on retrieval of LTM
- suggests ACh plays a role in encoding semantic and spatial memories

Strengths and Limitations:
- side effects of scopolamine
- somewhat artificial
- cause-and-effect established