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

Taxi VS Bus

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

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!

MRI of Hippocampus (Maguire et. al. 2000)

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?

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

Who? 18 Taxi drivers 17 Bus drivers

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

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? 5. In the last month, how often have you felt that things were going your way? From: http://www.macses.ucsf.edu/Research/Psychosocial/notebook/PSS10.html

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

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

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)

mpHippocampus Coronal Sagittal Axial

Neuropsychological Tests

Neuropsychological Tests cont.

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

Taxi driving exp. on volume

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

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

Thank you