Our experiments examine the neural basis of spatial cognition and the role of the hippocampus, parahippocampus and prefrontal cortex
Functional magnetic resonance imaging
Single unit recording
Dr Spiers has perviously used fMRI to scan licensed London taxi drivers while they navigated in a virtual simulation of London. Subjects were debriefed post-scan with a video replay of their performance and a verbal report protocol. During debriefing London taxi drivers reported a number of frequently occuring types of thoughts (e.g. planning a route) which were common across all subjects. From the debriefing, a time-series describing when these thoughts occured was generated for every subject (12,484 events, across 20 subjects). A summary of some of the findings is shown below:
The above figure is adapted from Spiers and Maguire 2007 Neuroscience.
A: Virtual London (the getaway (c) Sony Computer Entertainment Europe ), with London AZ map showing example route in grey
B: The route shown in A with the onsets and durations of different different categories of thought marked.
C: Schematic of the fMRI time series used to analyse the fMRI data
D: fMRI results from 4 of the categories are shown. Top right (red box) shows the left hippocampus more active during initial route planning.
Below is a summary of the findings from an article by the BBC
My neuropsychological research has found:
The right medial temporal lobe is necessary for finding one’s way in an environment, whilst the left medial temporal lobe is necessary for remembering what happened there (Spiers, et al., 2001 Brain)
The hippocampus is required to navigate newly explored environments, but not recognise objects seen in them. (Spiers, et al., 2001 Hippocampus)
The hippocampus is not required to navigate the major arterial routes in environments learned decades before, but is required when navigation depends upon a fine-grain knowledge of the environment (Maguire, Nannery, Spiers, 2006 Brain)
The hippocampus is necessary to rapidly construct a representation of the layout of an environment and to learn spatial and non-spatial configural stimulus-response associations (Lee et al., 2005 Hippocampus).
My voxel-based morphometry research as shown that:
The structural differences in London taxi driver brain morphology likely relates to their extensive spatial knowledge, rather than other factors such as driving experience and repeat exposure to traffic fumes, because London bus drivers do not show similar neuro-morphological changes (Maguire, Woollett, Spiers, 2006). Navigational ability is not related to hippocampal grey matter density (Maguire, Spiers et al., 2003).
The structural differences in London taxi driver brain morphology likely relates to their extensive spatial knowledge, rather than other factors such as driving experience and repeat exposure to traffic fumes, because London bus drivers do not show similar neuro-morphological changes (Maguire, Woollett, Spiers, 2006).
Navigational ability is not related to hippocampal grey matter density (Maguire, Spiers et al., 2003).
My fMRI research has revealed that:
Remembering events in a virtual town recruits a temporo-parietal network which extends to prefrontal regions when similar events have to be dissociated (Burgess et al., 2001).
Activity in the posterior right hippocampus is greater in successful navigators, bilateral anterior hippocampal regions have higher activity during accurate navigation and increases during the initial route planning (Hartley et al., 2003).
A network of brain regions, including the medial temporal, posterior parietal, retrosplenial and medial prefrontal cortices supports navigation in environments newly learned (Hartley et al., 2003) and learned in the remote past (Spiers and Maguire, 2006).
Navigating along an over-learned route does not significantly engage these regions (Hartley et al., 2003).
A complex choreography exists in this network during navigation, with each region responding to diverse requirements on a second-by-second basis, such as when route planning, mentalizing or planning actions (Spiers and Maguire, 2006).
A navigational guidance system may exist in the brain comprising the right medial temporal, medial prefrontal and posterior parietal corticies which track the distance and direction to goal locations during navigation (Spiers and Maguire, 2007).
My in vivo single unit recording has found:
Evidence that rat hippocampal cells increase their activity at the initiation of navigation to a hidden goal, a finding that accords with my own fMRI results, and those from another recent fMRI study by the Halberg group in Norway.
The hippocampal cell representation of a multi-compartmented environment is fragmented at the level of a bounded region of space, a finding consistent with recent results from the Moser group in Norway. Both results were reported at the Society for Neuroscience Meeting 2009 and being written up for publication.
Six different methods and approaches are used in the laboratory:
- Single unit in vivo electrophysiology
- Functional Magnetic Resonance Imaging
- Voxel based morphometry (VBM)
- Virtual reality
- We conduct our research with volunteers in the UCL Psychology and Language Sciences Division in Bedford Way.
- Our electrophsyiology is conducted in the IBN labs, which created with £3m SRIF funding and opened in 2008.
- fMRI scanning is conducted at the Birkbeck-UCL Centre for Neuroimaging (BUNCI)
- Our lab uses an Axona 32-channel DACQ recording system to acquire single cell recordings.
- We collect our fMRI data on a 1.5T Siemens Avanto at BUCNI which is also located in the same building as the IBN.
Page last modified on 04 mar 11 10:13