WIP Special

Goal-Planning in Psychosis: an fMRI study to investigate neuro-cognitive mechanisms of planning in psychosis

Presented by: Virginia Corno

Abstract: Schizophrenia is a serious mental condition that affects how people think, feel and perceive reality. Alongside psychotic symptoms like delusions and hallucinations, patients experience cognitive deficits, which have major impacts on day-to-day functioning. Of these, planning deficits are among the most consequential.

This study aims to understand the neurocognitive basis of planning impairment in schizophrenia, drawing on recent theoretical and empirical findings linking fronto-hippocampal representations to planning in rodents and healthy human volunteers. This prior work frames planning as a cognitive process that relies on the interaction between two complementary internal models: a world model, encoding where things are in the environment, and “duplicated structured representations” (DSRs) goal model, tracking an agent’s progress towards a goal in abstract task space. At the neural level, world model representations have been detected in hippocampal and medial entorhinal cortex, while DSRs have been detected in medial prefrontal and orbitofrontal cortices.

Although there is substantial evidence for hippocampal and prefrontal abnormalities in schizophrenia, there has been no direct examination of DSRs in the condition. To bridge this gap, we will recruit 50 patients with a history of psychosis and 50 healthy controls to complete a computerised planning task – the ABCD task - designed to disentangle world and DRS representations. Participants will complete the task while undergoing functional magnetic resonance imaging (fMRI). Prior work in mice and healthy human volunteers has demonstrated that this task affords an ability to detect DSR representations in frontal cortex, while participants are planning (El-Gaby et al. Nature; Küchenoff et al in prep).

Based on this prior work, we will use representational similarity analysis (RSA) to decode DSRs in the medial prefrontal cortex from BOLD activity. We will then relate these representations to performance in both the fMRI and language tasks, as well as symptom severity.

We hypothesise that, compared to healthy controls, patients with schizophrenia will show reduced DSRs in the prefrontal cortex, reduced world-model representations in the hippocampus, and reduced connectivity between them. Furthermore, we hypothesise that impairments in world model representations and DSRs will be related to impairments in behavioural markers of planning. Together, these findings will help us elucidate the neural mechanisms underlying planning impairments in schizophrenia, potentially informing new targets for treatment and biomarkers for precision psychiatry.

Neural Mechanisms of Blindsight in Congenital Hemianopia

Presented by: Rebecca Truby

Abstract TBC