London Taxi Drivers and Bus Drivers: A Structural MRI and Neuropsychological Analysis

1. London Taxi Drivers and Bus Drivers: A Structural MRI and Neuropsychological Analysis E.A. Maguire, K. Wollett & H.J. Spiers

2. Taxi VS Bus

3. Background • Taxi Drivers • “The Knowledge” • 2-4 yr training • 25,000 streets! • Bus drivers • Approx. 6 weeks of training • Drive ~12 set routes

5. MRI taxi drivers (Maguire et. al. 2000) • MRI shows • ↑ gray matter volume in p. hippocampus • ↓ gray matter volume in a. hippocampus • ↑ yrs driving taxi ↑ p. hippocampus & ↓ a. hippocampus!

6. MRI of Hippocampus (Maguire et. al. 2000)

7. Current Study: Is hippocampal ∆ really from spatial learning? • Driving around London requires: • Vigilance • Attention • Motor planning • Execution • Stress • May have impact on hippocampal gray matter?! • Is “The Knowledge” acquired at some expense?

8. Enter the Bus drivers! • Taxi vs. Bus drivers • To “control” for self-motivation, driving experience & stress on gray matter volume • Taxi • Free movement • Bus • Set route

9. Who? 18 Taxi drivers 17 Bus drivers

10. Neuropsychological Tests • Assessed • Basic cognitive memory • Working memory • Attention • Digit span (7 +/- 2) • Stress • Recognition • London land mark test • In London (yes/no) & which landmark closer

11. Perceived stress scale example • 1. In the last month, how often have you been upset because of something that happened unexpectedly? •  ___0=never ___1=almost never ___2=sometimes ___3=fairly often ___4=very often 2. In the last month, how often have you felt that you were unable to control the important things in your life? •  ___0=never ___1=almost never ___2=sometimes ___3=fairly often ___4=very often • 3. In the last month, how often have you felt nervous and "stressed"? • ___0=never ___1=almost never ___2=sometimes ___3=fairly often ___4=very often • 4. In the last month, how often have you felt confident about your ability to handle your personal problems? • ___0=never ___1=almost never ___2=sometimes ___3=fairly often ___4=very often • 5. In the last month, how often have you felt that things were going your way? • ___0=never ___1=almost never ___2=sometimes ___3=fairly often ___4=very often From: http://www.macses.ucsf.edu/Research/Psychosocial/notebook/PSS10.html

12. Procedure • Tested individually • One 2hr session • MRI & neuropsychological assessment in random order • 2 taxi drivers quit (claustrophobia in MRI)

14. http://www.youtube.com/watch?v=7g5UVrOt2CI

15. Results • Taxi drivers compared to Bus drivers • Greater gray matter volume in right/left mid-posterior hippocampi • Less volume in anterior head of right/left hippocampi • NO difference in Caudate Nucleus (learning & memory)

16. mpHippocampus Coronal Sagittal Axial

17. Neuropsychological Tests

18. Neuropsychological Tests cont.

20. No difference in Stress/Anxiety Not the reason for ∆ in Hippocampal size!

21. Taxi driving exp. on volume

22. Discussion • This study confirms 2000 study • “The Knowledge” comes with a price  • ↓acquiring/retrieving new visuo-spatial info • ∆’s not due to stress

23. Discussion cont. • “The Knowledge” becomes sharper with time • ↑Yrs driving taxi, ↑ p. hippocampi volume • Similar with musicians, jugglers & bilinguals • Costs/Benefits? • Evolutionarily? • Beyond London?

24. Thank you