Acute inflammation modulates substantia nigra responses to stimulus novelty and may underpin effects on exploratory behaviour

Harrison, N A, Cooper, E, Voon, V and Critchley, H D (2013) Acute inflammation modulates substantia nigra responses to stimulus novelty and may underpin effects on exploratory behaviour. Brain, Behavior, and Immunity, 32 (Supp). e26. ISSN 0889-1591

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Abstract

Introduction: Humans are naturally inquisitive. This tendency is adaptive, serving to reduce uncertainty associated with novel stimuli. Dopaminergic substantia nigra (SN) has been shown to mediate effects of novelty and motivation to explore novel and potentially valuable outcomes. Interestingly, inflammation impairs rodent exploration, limiting exposure to uncertain outcomes during times of limited metabolic resource. Though changes in SN activity are observed during inflammation-induced psychomotor slowing whether they also mediate effects on novelty and exploratory behaviour remains unknown. Methods: We scanned 17 healthy human participants twice, 3 h after experimental inflammation (Typhoid vaccination) and placebo (saline injection). Familiarised and novel face and place stimuli were presented during fMRI and magnetisation transfer images acquired to aid visualisation of SN. Results: Typhoid vaccination was associated with an increase in IL-6 and IL-1ra group x time interaction F (1,16) = 6.91, p < 0.02, F (1,16) = 11.77, p < 0.003 demonstrating induction of mild systemic inflammation. Face and place stimuli were associated with anticipated main effects in fusiform face and parahippocampal place area respectively. Neither region showed an interaction with stimulus novelty (p < 0.001). Right SN [10,−17,−16] demonstrated anticipated sensitivity to novelty for places following placebo. However, this was lost following inflammation: group x novelty interaction (p < 0.001). Conclusion: We have previously described SN sensitivity to mild inflammation, these data suggest this may impair processing of stimulus novelty and underpin inflammatory effects on exploratory behaviour.

Item Type: Article
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
Subjects: R Medicine
Depositing User: louisa Brooks
Date Deposited: 13 May 2014 14:35
Last Modified: 27 Jul 2017 18:00
URI: http://sro.sussex.ac.uk/id/eprint/48621
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