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Navigation-related structural change in the hippocampi of taxi drivers
3FA3- Module 4 Group A5 Swiya Nath Preeyam Randeria Catherine Leslie Tapiwa Musewe Nicholas Hawkes Tapiwa’s last name?
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Swiya Nath Target Article Aim : Test adult plasticity Method: Compare taxi driver’s brains to control subjects’ Conclusion: Adult hippocampus is plastic Changed wording a bit.
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Hippocampal size related to foraging behavior
Swiya Nath Hippocampal size related to foraging behavior Food storing species Bird species that store food have higher relative hippocampus size
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Hippocampal plasticity related to season of foraging
Swiya Nath Hippocampal plasticity related to season of foraging Retrieval Storing Number of large cells in anterior hippocampus increase during August Number of large cells in hippocampus increase during October
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Age Variance Average age = 44 years Range = 32-62 years
Preeyam Randeria Age Variance Average age = 44 years Range = years Not an accurate representation of the wide age group Can you make the font size of all titles the same as with the text?
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Training Variance Licensing training lasted = 10 months to 3.5 years
Preeyam Randeria Training Variance Licensing training lasted = 10 months to 3.5 years Average time spent before passing the licensing test = 2 years Amount of time spent on training can affect spatial development Spend = spent (typo)
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Divide the years of experience into two ranges
Preeyam Randeria Experience Variance Years of experience ranged = 1.5 years to 42 years Average years of experience = 14.3 years Too large a range, leads to inconsistency Divide the years of experience into two ranges
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Control Group’s Experience
Preeyam Randeria Control Group’s Experience Driving experience of the control group was not calculated More driving experience would result in a larger spatial capacity
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Preeyam Randeria Selection Bias MRI scans from control group was used to compare hippocampus sizes Record scans were used thus MRI scans were conducted for some deficit or problem Not representing the general population
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Socio-Economic Status (SES)
Preeyam Randeria Socio-Economic Status (SES) SES was not identified for drivers or the control group Control Group: lower SES might take public transportation more often and do not drive Drivers: different SES might depend on the type of area one works in Do examples need to be on slide?
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Preeyam Randeria Cause and Effect Did not measure or have records of the hippocampus size before the licensing training These individuals became taxi drivers because they were naturally better at spatial memory or vice versa? There is evidence for a correlation but not for a causal relationship Changed title, ALSO Second point can be said instead of typed?
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Uncontrolled Variables
Preeyam Randeria Uncontrolled Variables Education Level Based on education pursued, the taxi driver might already be used to memorizing Similar limitation with control group and between the control group and taxi drivers Deleted “for example” (I talked to Preeyam about this) and deleted (Cont.)
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Control Subjects 16 control subjects taken from a group of 50
Catherine Leslie Control Subjects 16 control subjects taken from a group of 50 Group of 50 came from MRI scan Database Not a random group of people Isn’t this a copy of Preeyam’s stuff (slide 10)
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Study cannot be generalized.
Catherine Leslie Sex Differences Study cannot be generalized. It has been proven that men and women are different in terms of spatial ability Differences in spatial functioning Differences in brain anatomy
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Spatial Functioning Components of Spatial Function
Catherine Leslie Spatial Functioning Components of Spatial Function Spatial Visualization –Mental rotation Spatial Perception – Water level task Spatial Memory – Visual features vs. location Spatial Orientation – Difference in used cues
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Brain Anatomy Men Women Catherine Leslie
Higher % of Working memory and cerebral spinal fluid Higher Amount of grey matter in left hemisphere Asymmetries Higher % of grey matter No asymmetries Tapiwa MIGHT be doing this (since its methodology)…haven’t discussed with Cate yet. Sex differences in brain anatomy may be able to explain differences in behaviour.
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Inter-rater Reliability
Tapiwa Musewe Inter-rater Reliability Pros Cons Eliminates rater - rater ambiguity Only measured by one expert Human errors Precision 24 X 32 Measurements Would strengthen results if corresponding measurements were found by multiple experts.
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Restrictive Selection
Tapiwa Musewe Restrictive Selection All participants were right-handed Prevented age-scale cluster Eliminated individual anatomical differences by creating one template Participants were all male
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Test – Retest Reliability
Tapiwa Musewe Test – Retest Reliability Used three different approaches to analyse volumetric changes in grey matter Magnetic Resonance Imaging (MRI) Provides detailed images of soft tissues in the brain Voxel-Based Morphology (VBM) Useful for determining neuroanatomical differences between individuals Allows anatomical differences of focal regions of the brain to be analysed rather than volumes of the whole brain Pixel counting Volume of hippocampus calculated by logical calculations
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Table of Contents Target Article Background Information
Critique Subject Selection Sex Bias Critique Methods Alternative Results Conclusion I don’t think we need my name in the TOC
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Swiya Nath Results Posterior hippocampus larger for taxi drivers than control subjects Anterior hippocampus larger for control subjects than taxi drivers Results more drastic in left hemisphere Adults show plasticity Too many words…I need help cutting them down.
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Posterior Hippocampus
Swiya Nath HIPER Model Anterior Hippocampus Posterior Hippocampus Smaller for taxi drivers than control subjects Larger for taxi drivers than control subjects Encoding Retrieval Also say how during ‘Knowledge Test = encoding, driving = retrieval?” “Food storing bird species – larger anterior hippocampus when storing” Question audience: what could have study tested to negate this alternative hypothesis? Do taxi drivers have more experience with spatial memory, or simply retrieval as the HIPER model suggests?
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Taxi Driver with Bilateral Hippocampal Damage
Swiya Nath Taxi Driver with Bilateral Hippocampal Damage Retrieval Encoding Well on spatial information (landmarks) Poor in actively navigating novel neighbourhoods Well on main roads Poor on detours What could be possible mechanisms that might be an answer to this puzzle? BUT lesion not isolated to posterior hippocampus
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Conclusion Selection bias = Randomized selection Sex bias = Lacks generalizability Test retest reliability HIPER model = Other memory test
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