Group B4 Members: Premraj Yogarajah Netra Malhotra Ruth Pedrosa Shawn Thaddaeus

SCHEDULE OF EVENTS: INTRODUCTION Background information Purpose METHODS The experiment The subjects Method I : Voxel-based Morphometry Method II : Pixel Counting RESULTS Hippocampal differences Further analysis DISCUSSION CONCLUSION

INTRODUCTION Methods Results Discussion Conclusion Differences in hippocampal volume amongst different species Background Information Hippocampus: facilitate spatial memory in the form of navigation PREM Morphonix LLC. (2007). Brain Speciments. The hippocampus. Retrieved October 7, 2008, Web Site:

Are morphological changes detectable in the healthy human brain associated with extensive experience of spatial navigation? INTRODUCTION Methods Results Discussion Conclusion Purpose PREM Crysler LLC. (2008). Features and Specs. Navigation. Retrieved October 7, 2008, Web Site:

Taxi drivers are ideally suited for this study Brain scans of London Taxi drivers compared with control group Introduction METHODS Results Discussion Conclusion The Experiment PREM

Taxi Drivers (16)Control Subjects (50) Male Right-Handed Mean age = 44 Range = years Mean age = 44 Range = 32 – 62 years Mean Experience = 14.3 years Range = years N/A Average Training = 2 years Range = 10 months – 3.5 years N/A Introduction METHODS Results Discussion Conclusion Test Subjects Table 1. Comparison of Subjects Vs. Control participants PREM

Introduction METHODS Results Discussion Conclusion Image Analysis Method 1: VBM (Voxel-Based Morphometry) SHAWN Image Acquisition: Structural MRI – 2.0 Tesla Vision System VBM: subject’s data were spatially normalized into stereotactic space using a template image Template from structural scans of 50 healthy males (13 controls included) Spatially normalized images - segmented into gray matter, white matter, and cerebrospinal fluid VBM allows to objectively identify regional differences in gray matter density using the structural MRI images

Introduction METHODS Results Discussion Conclusion Method 2: Pixel Counting SHAWN Pixel Counting Technique: VBM analysis of 50 subjects: 3D images from 16 taxi driver and 16 control subjects were used for volumetric measurement of both hippocampi Hippocampal cross-sectional areas were measured Grouped into 3 regions: posterior hippocampus (6 slices), body (12 slices), and anterior (6 slices) Total hippocampal volume calculated by summing cross- sectional areas and multiplying by the distance between adjacent slices

Taxi drivers: increased gray matter volume in the posterior hippocampus bilaterally Control: relatively greater gray matter volume bilaterally in anterior hippocampi Introduction Methods RESULTS Discussion Conclusion Hippocampal Differences NETRA

Introduction Methods RESULTS Discussion Conclusion Further Analysis NETRA Figure2. Regionally specific volume differences between taxi drivers and control group

Introduction Methods RESULTS Discussion Conclusion Further Analysis NETRA Figure 3. Correlation between the length of time spent as a taxi driver with hippocampus volume

Regionally specific structural differences between the hippocampi Suggests plasticity in hippocampal gray matter as a function of increasing exposure to an environmental stimulus Introduction Methods Results DISCUSSION Conclusion Discussion RUTH

Posterior hippocampal region - previous learned spatial information Anterior hippocampal region - encodes new environmental layouts Normal activities can induce changes in the relative volume of gray matter Implications for rehabilitation Introduction Methods Results Discussion CONCLUSION Conclusion RUTH

References Introduction Methods Results Discussion CONCLUSION Crysler LLC. (2008). Features and Specs. Navigation. Retrieved October 7, 2008, Web Site: Lee, D.W., Miyasato, I.E. & Clayton, N.S. (1998) Neuroreport 9. R15-R27 Maguire, Eleanor A., et al. (2000) Navigation-related structural change in the hippocampi of taxi drivers. PNAS, vol. 97. Morphonix LLC. (2007). Brain Speciments. The hippocampus. Retrieved October 7, 2008, Web Site: pus.gif O’Keefe, J. &Nadel, L. (1978) The hippocampus as a Cognitive Map (Clarendon, Oxford). Terrazaz, A. & McNaughton, B. (2000). Brain growth and the cognitive map. PNAS, vol. 97, no. 9.