Draganski et al (2004)

Uses: Neuroplasticity / Imaging technique (MRI)

Aim:  To investigate whether structural changes in the brain would occur in response to practicing a simple juggling routine.

Method: True experiment

Procedure:

  • 24 volunteers, 21 female and 3 male. They are all non-jugglers and were split into the jugglers and the control group.

  • Jugglers’ and non-jugglers’ brains are scanned before any form of routine.

  • After 3 months of practice or when the jugglers have mastered their juggling, both groups’ brains are scanned again.

  • After 3 months of not practicing, both groups’ brains are scanned again.

Results:

Prior to the experiment, there are no structural differences between the jugglers and non-jugglers. After 3 months of practice, jugglers have more (denser) grey matter in the mid-temporal area of the cortex in both hemispheres, they are responsible for the coordination of movement and visual memory. The increase in density of the temporal lobe indicates dendritic branching as a result of learning. After six months, the juggler's differences with the control group have decreased but they still possess denser grey matter than the first scan. This is interpreted as the work of neural pruning. When the participants stopped juggling, grey matter's density decreased over time which is a reduction in the connection.

Conclusion:

Grey matter grows in the brain in response to environmental demands such as learning and shrinks in the absence of stimulation. There is a cause-and-effect relationship between learning and brain structure.

Evaluation:

Pros:

  • Dragonski's experiment is highly ethical.

  • The study used a pre-test, post-test design to show differences in neural density over time.

  • The study was experimental, thus helping to argue for a cause-and-effect relationship.

  • There was a control group that didn't juggle that served as a control group.

Cons:

  • Small sample size, imbalanced gender ratio, similar age = sampling bias

  • The study has potential problems with internal validity as the participants were in their home environments for a good part of the study.

  • The study would need to be replicated to establish its reliability.

  • Can’t be directly observed.

  • A very specific skill set, may not show ecological validity.

Bogdan Draganski, C. G. (2004). Neuroplasticity: changes in grey matter induced by training.