Poster Session B, Sunday, March 24, 8:00 – 10:00 am, Pacific Concourse
Object-location association binding is transiently impaired during post-traumatic amnesia
Emma-Jane Mallas1, Gregory Scott1, Rituja Kamble1, David J. Sharp1, Nikos Gorgoraptis1; 1Imperial College London
Patients with moderate-severe traumatic brain injury (TBI) will typically experience post-traumatic amnesia, a transient period of impaired orientation, anterograde memory and working memory (WM). WM impairment in PTA is associated with reduced functional-connectivity within the medial-temporal lobe (De Simoni et al.,2016), regions of known importance for the integration of object identity and spatial information. Here, we examined whether PTA patients (n=15) demonstrated impaired object-location binding in WM compared to TBI (n=9) and healthy controls (n=15) and reassessed their performance on resolution of PTA. Participants memorised the location of one or two fractal shapes and were asked to identify and relocate the target item to its remembered location. In two-item trials where the target was correctly identified, we examined how its remembered location was biased by the location of the non-target item using i) a measure of the proportion of ‘swap-errors’ as in Pertzov et al (2012) and ii) a novel approach to study the distribution of responses in a normalised space. PTA patients demonstrated impaired recognition memory compared with controls (p<0.001) but not TBI (p=0.09). Localisation was impaired within correct two-item trials: PTA made significantly more swap-errors than TBI (p<0.0001) and controls (p<0.0001), with placement biased by the non-target significantly more than TBI (p=0.02) and controls (p=0.01). Following recovery, this impairment resolved compared to TBI (p=0.60). The influence of the non-target object in correctly identified trials suggests that patients in PTA are able to encode information about an object’s individual features (identity and location) but fail in binding these together.
Topic Area: EXECUTIVE PROCESSES: Working memory