J Korean Soc Magn Reson Med.  2012 Aug;16(2):124-135. 10.13104/jksmrm.2012.16.2.124.

Structural and Functional Changes of Hippocampus in Long Life Experienced Taxi Driver

• You MW
• Lee DK
• Lee JM
• Kim SM
• Ryu CW
• Kim EJ
• Jahng GH

• KMID: 2099846
• DOI: http://doi.org/10.13104/jksmrm.2012.16.2.124

Abstract

PURPOSE
The objective of this study was to investigate the differences of hippocampal volume and shape as well as the functional change between long life experienced taxi drivers and controls of Korean population.
MATERIALS AND METHODS
Three-dimensional T1-weighted images and blood oxygen level dependent functional MRI(fMRI) were obtained from 8 subjects, consisting of 4 experienced (20-30 years) taxi drivers and 4 age-matched controls. The hippocampal volume and shape were analyzed with three-dimensional T1-weighted images. In addition, neuronal activities of brain were analyzed using a blood oxygen level dependent fMRI between the two groups.
RESULTS
The hippocampal volume showed no statistically significant difference between the two groups (p > 0.05). The left hippocampi of the taxi drivers were slightly elongated with larger head and tail portions than those of the controls (p < 0.05, uncorrected). For the functional MRI, fusiform gyrus was specifically activated in taxi drivers, compared with the control group.
CONCLUSION
The structural and functional changes of taxi driver's hippocampus indicate the functional differentiation as a result of occupational dependence on spatial navigation. In other words, the continuous usage of spatial navigation performance may diminish degeneration of hippocampus and the related brain regions.

Keyword

Hippocampus; Behavior; Magnetic resonance imaging (MRI); Orientation

MeSH Terms

Brain
Head
Hippocampus
Magnetic Resonance Imaging
Neurons
Orientation
Oxygen
Oxygen

Figure

• 

  Fig. 1 A sample of road maps (A) and control maps (B) that was used during the functional MRI task. The four different question pictures were shown during the stimulation period. A. An example of road map (a). An overall picture showing the starting point (red), stop by point (green) and the final destination point (blue). (b). A close-up image showing the starting point (red). (c). A close-up image showing the stop by point (green). (d). A close-up image showing the final destination point (blue). B. The control maps. The four different crossroad pictures were shown during the baseline period.

• 

  Fig. 2 The morphometric analysis with reconstructed hippocampal structures using spherical harmonic descriptors. The left hippocampus of taxi driver group is shown in this figure with slightly elongated mean distances from center of the mass to each vertex and larger head (open arrows) and tail (thick black arrows) portions. The comparison of mean distance value between the two group was recorded as color spectrum (uncorrected p < 0.05). Areas that have statistically significant differences in hippocampal shape between the taxi driver group and the control, are shown here as black colored region-head and tail portions of hippocampus.

• 

  Fig. 3 Activated brain regions in the functional MRI study of the taxi driver group (a) and the control group (b) are shown. a. The taxi drivers show neuronal activation mainly in the temporal lobe and fusiform gyrus. b. The controls show neuronal activation mainly in the frontal and parietal lobes.

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