LEW, ADINA,RAQUEL (2019) The well-worn route revisited: Striatal and hippocampal system contributions to route learning in human navigation. Masters thesis, Durham University.
|Full text not available from this repository.|
Author-imposed embargo until 01 November 2020.
Available under License Creative Commons Public Domain Dedication CC0 1.0 Universal.
Parallel spatial memory systems theory posits that there are two types of memory system. One is a flexible, cognitive mapping system subserved by the hippocampal formation, and the other is a system centred on the striatum based on reinforcement learning principles where specific stimuli are associated with rewarded actions (O’Keefe & Nadel, 1978; White & McDonald, 2002). More recently, Khamassi & Humphries (2012) have argued that the division between model-based and model-free spatial learning is a better predictor of whether hippocampal or striatal systems will be recruited, with hippocampal systems associated with model-based responding and striatal systems with model-free responding. Model-free decision-making occurs when responding is based on average reward history associated with a particular cue-action pairing, whereas model-based decision-making allows knowledge of outcomes from previous learning history to be represented. We sought to test these theories by asking participants (N = 24) to navigate within a virtual environment through a previously learned, 9-junction route with distinctive landmarks at each junction, while undergoing functional magnetic resonance imaging. In critical conflict probe trials, a landmark was presented out of sequence such that following the usual sequence of actions would generate an opposite response to following the learned individual landmark-action association, now out of sequence. Participants that made sequence-based responses had higher parahippocampal activations relative to participants that made responses based on the individual landmark-action association, a result that would be predicted by the need to recruit model-based systems to make a sequence-based response. Parallel spatial memory systems theory would not predict hippocampal formation recruitment for either response in the conflict probe, because no cognitive mapping is required when following a prescribed route. In longer probe trials where participants were able to plan a sequence of responses, striatal systems were recruited (caudate and putamen) suggesting a role for striatum in action chunking.
|Item Type:||Thesis (Masters)|
|Award:||Master of Science|
|Keywords:||Parallel Spatial Memory Systems, Navigation, Hippocampus, Striatum|
|Faculty and Department:||Faculty of Science > Psychology, Department of|
|Copyright:||Copyright of this thesis is held by the author|
|Deposited On:||30 Oct 2019 13:50|