Brain Communications
2024
Miriam Vignando, Dominic H Ffytche, Ndaba Mazibuko et al.
7 citations
Abstract Psychosis and visual hallucinations are a prevalent non-motor symptom of Parkinson's disease, negatively affecting patients’ quality of life and constituting a greater risk for dementia. Understanding neural mechanisms associated to these symptoms is instrumental for treatment development. The mismatch negativity is an event-related potential evoked by a violation in a sequence of...
Journal of Neurology
November 2023
Ahmad Beyh, Samuel E Rasche, Alexander Leff et al.
The Riddoch syndrome is one in which patients blinded by lesions to their primary visual cortex can consciously perceive visual motion in their blind field, an ability that correlates with activity in motion area V5. Our assessment of the characteristics of this syndrome in patient ST, using multimodal MRI, showed that: 1. ST's V5 is intact, receives direct subcortical input, and decodable...
Neuroscience & Biobehavioral Reviews
July 1, 2023
Daniel Collerton, James Barnes, Nico J Diederich et al.
80 citations
Despite decades of research, we do not definitively know how people sometimes see things that are not there. Eight models of complex visual hallucinations have been published since 2000, including Deafferentation, Reality Monitoring, Perception and Attention Deficit, Activation, Input, and Modulation, Hodological, Attentional Networks, Active Inference, and Thalamocortical Dysrhythmia Default...
Brain
October 24, 2017
Matt Ffytche, Dominic H Ffytche
What does an eminent neuroanatomist dream of at night? The panic of being an auxiliary professor and receiving last minute instructions from the Dean to lecture on osteology? ‘Anxiety, distress … upon reviewing the bones in my memory. I list those of the hand: scaphoids, capitate, and I did not know any more’; or perhaps of secretly cutting slices of medulla for staining in a boarding house at...
Psychopharmacology
July 19, 2014
Judith Nottage, James Stone, Robin Murray et al.
34 citations
RATIONALE: An acute challenge with delta-9-tetrahydrocannabinol (THC) can induce psychotic symptoms including delusions. High electroencephalography (EEG) frequencies, above 20 Hz, have previously been implicated in psychosis and schizophrenia. OBJECTIVES: The objective of this study is to determine the effect of intravenous THC compared to placebo on high-frequency EEG. METHODS: A double-blind...
Schizophrenia Bulletin
July 1, 2014
Flavie Waters, Daniel Collerton, Dominic H Ffytche et al.
Much of the research on visual hallucinations (VHs) has been conducted in the context of eye disease and neurodegenerative conditions, but little is known about these phenomena in psychiatric and nonclinical populations. The purpose of this article is to bring together current knowledge regarding VHs in the psychosis phenotype and contrast this data with the literature drawn from...
Neuropsychopharmacology
June 2011
Toby T Winton-Brown, Paul Allen, Sagnik Bhattacharyya et al.
Although the effects of cannabis on perception are well documented, little is known about their neural basis or how these may contribute to the formation of psychotic symptoms. We used functional magnetic resonance imaging (fMRI) to assess the effects of Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) during visual and auditory processing in healthy volunteers. In total, 14 healthy...
Brain
January 2011
Dominic H Ffytche, Semir Zeki
A compelling single case report of visual awareness (visual qualia) without primary visual cortex would be sufficient to refute the hypothesis that the primary visual cortex and the back-projections to it are necessary for conscious visual experience. In a previous study, we emphasized the presence of crude visual awareness in Patient G.Y., with a lesion of the primary visual cortex, who is...
Advances in Consciousness Research
October 28, 2010
Dominic H Ffytche
Neurobiological accounts of consciousness typically partition brain activity into two components: one correlated with conscious experience (the neural correlate of consciousness) and the other not. Here I use evidence derived from visual hallucinations in the context of eye disease – the Charles Bonnet Syndrome – to examine the nature of what might be termed the visual unconscious. Forcing us...
Cortex
February 1, 2006
Jeffrey A Gray, David M Parslow, Michael J Brammer et al.
Coloured hearing synaesthetes experience colours to heard words, as confirmed by reliability of self-report, psychophysical testing and functional neuroimaging data. Some also describe the 'alien colour effect' (ACE): in response to colour names, they experience colours different from those named. We have previously reported that the ACE slows colour naming in a Stroop task, reflecting...