Thomas Burne
Queensland Brain Institute, Australia
Title: Motivation and decision making in developmentally Vitamin D deficient rats
Biography
Biography: Thomas Burne
Abstract
Developmental Vitamin D (DVD) deficiency in rats is associated with alterations in brain development and behaviour, with features of relevance to schizophrenia. Although the DVD model does not replicate every aspect of schizophrenia, it has several prominant features; the exposure is based on clues from epidemiology, it reproduces the increase in size of the lateral ventricles and it reproduces well-regarded behavioural phenotypes associated with schizophrenia (e.g. hyperlocomotion). While hallucinations and delusions (positive symptoms) feature prominently in diagnostic criteria, impairments of cognitive symptoms, including attentional processing and behavioural inhibition are core features of schizophrenia. Our aim was to investigate aspects of response inhibition and impulsivity in control and DVD-deficient rats. DVD-deficient rats demonstrated mildly enhanced impulsivity and response inhibition as measured using the 5 choice continuous performance task and the differential reinforcement task. There were no significant effects of maternal diet on delay-dependent memory, or on choice of small or large rewards using delay discounting. However, DVD-deficient rats had a significant delay in response latency in performance on both tasks, which suggests they had altered levels of motivation to perform the task. This was confirmed with DVD-deficient rats having a reduced break point using a progressive ratio task. We have previously shown that the dopamine system is altered in DVD deficient rats and, given the role of dopamine in motivation and reward, this may underly the deficits seen within the model. The DVD-deficient rat model is characterised by a phenotype reminiscent of both positive and negative symptoms of schizophrenia, and these results suggest that DVD-deficient rats also have specific impairments in motivation.