50 research outputs found
Investigation into the mechanisms of depressive illness
Functional and structural brain abnormalities have been reported in many imaging
studies of depressive illness. However, the mechanisms by which these
abnormalities give rise to symptoms remain unknown. The work described in this
thesis focuses on such mechanisms, particularly with regard to neural predictive error
signals. Recently, these signals have been reported to be present in many studies on
animals and healthy humans. The central hypothesis explored in this thesis is that
depressive illness comprises a disorder of associative learning. Chapter 2 reviews
the brain regions frequently reported as abnormal in imaging studies of depressive
illness, and the normal function of these particular brain regions. It is concluded that
such regions comprise the neural substrate for associative learning and emotion.
However, confidence in this conclusion is limited by considerable variability in the
human imaging literature. Therefore, chapter 3 describes a meta-analysis, which
tests the hypothesis that, consistent with the non-imaging literature, the ventromedial
prefrontal cortex is most active during emotional experience. The results of the
meta-analysis were clearly consistent with this hypothesis. Chapter 4 provides an
introduction to neural predictive error signals from the general perspective of
homeostatic physiological regulation. Both experimental evidence supporting the
error signals, and various formal mathematical theories describing the error signals,
are summarised. This provides the background to chapter 5, which describes an
original fMRI study which tested the hypothesis that patients with depressive illness
would exhibit abnormal predictive error signals in response to unexpected
motivationally significant stimuli. Evidence of such abnormality was found.
Chapter 6 describes a further original study using transcranial ultrasound and
diffusion tensor imaging of the brainstem, which investigated reports of a subtle
structural abnormality in depressed patients. If present, it might give rise to
abnormal error signals. However, no structural abnormality was found. Finally,
chapter 7 discusses the significance of these findings in the context of clinical
features of depressive illness and a wide range of treatments, ranging from
psychotherapy through antidepressants to physical treatments. A number of potential
future studies are identified, which could clarify understanding of depressive illness
Dementia in Parkinson’s Disease
An estimated 50% to 80% of individuals with Parkinson’s disease experience Parkinson’s disease dementia (PDD). Based on the prevalence and clinical complexity of PDD, this book provides an in-depth update on topics including epidemiology, diagnosis, and treatment. Chapters discuss non-medical therapies and examine views on end-of-life issues as well. This book is a must-read for anyone interested in PDD whether they are a patient, caregiver, or doctor
The Stylometric Processing of Sensory Open Source Data
This research project’s end goal is on the Lone Wolf Terrorist.
The project uses an exploratory approach to the
self-radicalisation problem by creating a stylistic fingerprint
of a person's personality, or self, from subtle characteristics
hidden in a person's writing style. It separates the identity of
one person from another based on their writing style. It also
separates the writings of suicide attackers from ‘normal'
bloggers by critical slowing down; a dynamical property used to
develop early warning signs of tipping points. It identifies
changes in a person's moods, or shifts from one state to another,
that might indicate a tipping point for self-radicalisation.
Research into authorship identity using personality is a
relatively new area in the field of neurolinguistics. There are
very few methods that model how an individual's cognitive
functions present themselves in writing. Here, we develop a
novel algorithm, RPAS, which draws on cognitive functions such as
aging, sensory processing, abstract or concrete thinking through
referential activity emotional experiences, and a person's
internal gender for identity. We use well-known techniques such
as Principal Component Analysis, Linear Discriminant Analysis,
and the Vector Space Method to cluster multiple
anonymous-authored works. Here we use a new approach, using
seriation with noise to separate subtle features in individuals.
We conduct time series analysis using modified variants of 1-lag
autocorrelation and the coefficient of skewness, two statistical
metrics that change near a tipping point, to track serious life
events in an individual through cognitive linguistic markers.
In our journey of discovery, we uncover secrets about the
Elizabethan playwrights hidden for over 400 years. We uncover
markers for depression and anxiety in modern-day writers and
identify linguistic cues for Alzheimer's disease much earlier
than other studies using sensory processing. In using these
techniques on the Lone Wolf, we can separate their writing style
used before their attacks that differs from other writing