Graph Theory

Semantic speech networks linked to formal thought disorder in early psychosis

Mapping a patient's speech as a network has proved to be a useful way of understanding formal thought disorder in psychosis. However, to date, graph theory tools have not incorporated the semantic content of speech, which is altered in psychosis. We developed an algorithm, netts, to map the semantic content of speech as a network, then applied netts to construct semantic speech networks for a general population sample, and a clinical sample comprising patients with first episode psychosis (FEP), people at clinical high risk of psychosis (CHR-P), and healthy controls. Semantic speech networks from the general population were more connected than size-matched randomised networks, with fewer and larger connected components, reflecting the non-random nature of speech. Networks from FEP patients were smaller than from healthy participants, for a picture description task but not a story recall task. For the former task, FEP networks were also more fragmented than those from controls; showing more, smaller connected components. CHR-P networks showed fragmentation values in-between FEP patients and controls. A clustering analysis suggested that semantic speech networks captured novel signal not already described by existing NLP measures. Network features were also related to negative symptom scores and scores on the Thought and Language Index, although these relationships did not survive correcting for multiple comparisons. Overall, these data suggest that semantic networks can enable deeper phenotyping of formal thought disorder in psychosis. We are releasing Netts as an open Python package alongside this manuscript.

Capturing fragmented speech in psychosis using Networks of Transcribed Speech

Towards transcribed speech networks as a marker for psychosis risk

Recent work has shown that incoherent speech is a powerful predictor of psychosis. Predicting psychosis risk from speech data could revolutionise healthcare for psychosis, for two reasons. First, there is a pressing clinical need for tools to aid …

The role of disorganised speech in psychosis

Incoherent speech has emerged as a potential predictor of psychosis. Predicting psychosis risk from speech data could markedly improve healthcare for psychosis. In this talk, I will review existing tools for predicting psychosis risk from speech …

Graph Theory

Lecture introducing concepts from Graph Theory and Network Neuroscience, as part of the Introduction to Neuroimaging Methods lecture series at the University of Cambridge MRC CBU. The seminar includes practical exercises. For exercise material and solutions see links below.

Graph Theory Lecture

Introduction to Graph Theory in Neuroimaging