Why people see things that are not there: A novel Perception and Attention Deficit model for recurrent complex visual hallucinations

2005 ◽  
Vol 28 (6) ◽  
pp. 737-757 ◽  
Author(s):  
Daniel Collerton ◽  
Elaine Perry ◽  
Ian McKeith
Keyword(s):  
Frontal Cortex ◽  
Attention Deficit ◽  
Scene Perception ◽  
Treatment Options ◽  
Visual Hallucinations ◽  
Visual Stream ◽  
Cortical Hyperexcitability ◽  
Scene Representation ◽  
Ventral Visual Stream ◽  
Context Specific

As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex–ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates.

Using Convolutional Neural Networks to measure the contribution of visual features to the representation of object animacy in the brain

2019 ◽  
Author(s):  
Sushrut Thorat
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Temporal Cortex ◽  
Large Degree ◽  
Visual Features ◽  
Visual Feature ◽  
Visual Stream ◽  
Feature Information ◽  
Ventral Visual Stream ◽  
Animal Images

A mediolateral gradation in neural responses for images spanning animals to artificial objects is observed in the ventral temporal cortex (VTC). Which information streams drive this organisation is an ongoing debate. Recently, in Proklova et al. (2016), the visual shape and category (“animacy”) dimensions in a set of stimuli were dissociated using a behavioural measure of visual feature information. fMRI responses revealed a neural cluster (extra-visual animacy cluster - xVAC) which encoded category information unexplained by visual feature information, suggesting extra-visual contributions to the organisation in the ventral visual stream. We reassess these findings using Convolutional Neural Networks (CNNs) as models for the ventral visual stream. The visual features developed in the CNN layers can categorise the shape-matched stimuli from Proklova et al. (2016) in contrast to the behavioural measures used in the study. The category organisations in xVAC and VTC are explained to a large degree by the CNN visual feature differences, casting doubt over the suggestion that visual feature differences cannot account for the animacy organisation. To inform the debate further, we designed a set of stimuli with animal images to dissociate the animacy organisation driven by the CNN visual features from the degree of familiarity and agency (thoughtfulness and feelings). Preliminary results from a new fMRI experiment designed to understand the contribution of these non-visual features are presented.

scholarly journals Systematic review of transdermal treatment options in attention-deficit/hyperactivity disorder: implications for use in adult patients

CNS Spectrums ◽  
2021 ◽  
pp. 1-13
Author(s):  
Christoph U. Correll ◽  
Brittney R. Starling ◽  
Michael Huss
Keyword(s):  
Attention Deficit Hyperactivity Disorder ◽  
Attention Deficit ◽  
English Language ◽  
Treatment Options ◽  
Adult Patients ◽  
Publication Date ◽  
Potential Cost ◽  
Hyperactivity Disorder ◽  
Related Quality ◽  
Treatment Safety

Abstract Background Adults with attention-deficit/hyperactivity disorder (ADHD) often face delays in diagnosis and remain untreated, despite significant negative impacts. To evaluate the safety and efficacy of transdermal treatment options in children, adolescents, and adults, a systematic literature review was conducted, with a focus on the implications of transdermal therapies for ADHD in adults. Methods A MEDLINE/Embase/BIOSIS/SCOPUS database search was conducted December 4, 2019, for English-language articles of interventional clinical trials using transdermal formulations for the treatment of ADHD without publication date limit. Assessed outcomes included efficacy, safety, adherence, abuse potential, cost efficacy, and health-related quality of life. Results Of 23 eligible publications, 18 were in children or adolescents (n = 1699; range 23-305), and 5 in adults (n = 274; range 14-90); all included methylphenidate transdermal system (MTS). All seven pediatric publications reporting change in ADHD symptomology from baseline reported a significant improvement with MTS treatment. Similarly, in three adult publications, ADHD symptoms improved significantly with MTS treatment. Safety findings in pediatric and adult studies were comparable; the most frequently reported treatment-emergent adverse events (TEAEs), namely, headache, decreased appetite, and insomnia, were reported in 13/16 (81%) of publications reporting specific TEAEs. MTS-related dermal reactions were mostly mild and transient. Discontinuation due to dermal reactions was reported in 10 studies (range 0%-7.1% [1 of 14 patients]). MTS compliance was high when assessed (97%-99%). Conclusions Transdermal therapies provide a useful treatment formulation for ADHD. Studies of MTS and other transdermal formulations, such as amphetamine, in adult patients are needed in this underserved population.

Orthographic processing deficits in developmental dyslexia: Beyond the ventral visual stream

NeuroImage ◽  
2016 ◽  
Vol 128 ◽  
pp. 316-327 ◽  
Author(s):  
Marianna Boros ◽  
Jean-Luc Anton ◽  
Catherine Pech-Georgel ◽  
Jonathan Grainger ◽  
Marcin Szwed ◽  
...  
Keyword(s):  
Developmental Dyslexia ◽  
Orthographic Processing ◽  
Visual Stream ◽  
Ventral Visual Stream ◽  
Processing Deficits

scholarly journals Glucagon Like Peptide-1 and Its Receptor in Human Brain: Distribution of Expression, Functional Implications, Age Related Changes & Species Specific Characteristics

2021 ◽  
Author(s):  
Tulika Gupta ◽  
◽  
Mandeep Kaur ◽  
Devendra Shekhawat ◽  
Ritu Aggarwal ◽  
...  
Keyword(s):  
Human Brain ◽  
Frontal Cortex ◽  
Brain Mapping ◽  
Treatment Options ◽  
Cortical Areas ◽  
Western Blot Method ◽  
Age Related ◽  
Immuno Histochemistry ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Emerging evidence has shown that the Glucagon like peptide-1 (GLP-1) agonist can be used for treating Alzheimer’s disease, but knowledge of its neural targets is limited. To understand the neural substrates of GLP-1, we have done whole brain mapping for GLP-1 and its receptor (GLP-1R), in 30 human brains. GLP-1 expression was studied by immuno-histochemistry and confirmed by western blot method. GLP-1R gene expression was studied by RT-PCR. GLP-1 expression was seen in most of the cortical areas (maximum in frontal, prefrontal & parietal cortex), diencephalon and brainstem, but not in cerebellum. Protein expression studies validated these results. Highest expression of GLP-1R was found in the frontal cortex. The orbito-frontal cortex and cerebellum had negligible expression. Hippocampus demonstrated significant presence of GLP-1R but patchy immunoreactivity to GLP-1. GLP-1R presence in most of the human cortical regions and absence in cerebellum is the major deviation from the animal brain. Sites which might be of interest in Alzheimer’s have been identified. GLP-1 demonstrated age related decline in most of the areas after 5thdecade. At 60yrs GLP-1 was not found in any of the cortical areas except in the prefrontal cortex but it was present in the sub-cortical areas. Age related profiling of GLP-1 in various brain areas has been analysed, which can have important bearing on understanding the Alzheimer’s. This study provides detailed description of GLP-1 and GLP-1R locations by complete human brain mapping for the first time and may lead to novel treatment options targeting the GLP-1 receptors.

scholarly journals Predictive coding of action intentions in dorsal and ventral visual stream is based on visual anticipations, memory-based information and motor preparation

2018 ◽  
Author(s):  
Simona Monaco ◽  
Giulia Malfatti ◽  
Alessandro Zendron ◽  
Elisa Pellencin ◽  
Luca Turella
Keyword(s):  
Visual Information ◽  
Visual Memory ◽  
Visual Recognition ◽  
Predictive Coding ◽  
Action Planning ◽  
Neural Signals ◽  
Motor Representation ◽  
Visual Stream ◽  
Ventral Visual Stream ◽  
Action Intention

AbstractPredictions of upcoming movements are based on several types of neural signals that span the visual, somatosensory, motor and cognitive system. Thus far, pre-movement signals have been investigated while participants viewed the object to be acted upon. Here, we studied the contribution of information other than vision to the classification of preparatory signals for action, even in absence of online visual information. We used functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis (MVPA) to test whether the neural signals evoked by visual, memory-based and somato-motor information can be reliably used to predict upcoming actions in areas of the dorsal and ventral visual stream during the preparatory phase preceding the action, while participants were lying still. Nineteen human participants (nine women) performed one of two actions towards an object with their eyes open or closed. Despite the well-known role of ventral stream areas in visual recognition tasks and the specialization of dorsal stream areas in somato-motor processes, we decoded action intention in areas of both streams based on visual, memory-based and somato-motor signals. Interestingly, we could reliably decode action intention in absence of visual information based on neural activity evoked when visual information was available, and vice-versa. Our results show a similar visual, memory and somato-motor representation of action planning in dorsal and ventral visual stream areas that allows predicting action intention across domains, regardless of the availability of visual information.

scholarly journals Parallel processing of colors and faces in human ventral visual stream: functional evidence and technical challenges

2014 ◽  
Vol 14 (10) ◽  
pp. 985-985
Author(s):  
R. Lafer-Sousa ◽  
A. Kell ◽  
A. Takahashi ◽  
J. Feather ◽  
B. Conway ◽  
...  
Keyword(s):  
Parallel Processing ◽  
Visual Stream ◽  
Ventral Visual Stream ◽  
Technical Challenges

scholarly journals Improvement in refractory psychosis after initiating management for underlying ADHD

2015 ◽  
Vol 84 (S1) ◽  
pp. 6-8
Author(s):  
Michael Blaszak ◽  
Danica Brister ◽  
Jordon Charlebois ◽  
Erica Hoe ◽  
Maggie Siu
Keyword(s):  
Attention Deficit Hyperactivity Disorder ◽  
Case Report ◽  
Clinical Practice ◽  
Attention Deficit ◽  
Clinical Case ◽  
Psychotic Symptoms ◽  
Visual Hallucinations ◽  
Hyperactivity Disorder ◽  
Stimulant Medications ◽  
Pathophysiologic Mechanisms

We report on a unique clinical case of psychosis precipitated by Attention Deficit Hyperactivity Disorder (ADHD) and explore its implications for clinical practice as well as our understanding of these conditions. We describe a clinical case of a 46-year-old male presenting with auditory, olfactory, tactile, and visual hallucinations. We reviewed the literature on reported cases in which psychotic symptoms were treated with stimulant medications for ADHD comorbidity. This case report reveals the potential for properly selected patients to benefit from a consideration of ADHD comorbidity and a trial of treatment with that focus. In addition, the literature reveals a pathophysiologic association between psychosis and ADHD supported by neurobiological data. However, far more research is required to fully understand these conditions and their relationship. We conclude that ADHD and psychosis have some related pathophysiologic mechanisms but their connection has not been adequately explored. This case adds support to literature suggesting that in refractory psychosis, clinicians should re-evaluate the diagnosis and one of the considerations should be ADHD. In certain cases, the presence of psychotic symptoms with ADHD should not exclude the use of stimulants.

scholarly journals Image content is more important than Bouma’s Law for scene metamers

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Thomas SA Wallis ◽  
Christina M Funke ◽  
Alexander S Ecker ◽  
Leon A Gatys ◽  
Felix A Wichmann ◽  
...  
Keyword(s):  
Perceptual Experience ◽  
Receptive Fields ◽  
Natural Images ◽  
Retinal Eccentricity ◽  
High Fidelity ◽  
Prior Work ◽  
Visual Stream ◽  
Area V2 ◽  
Ventral Visual Stream ◽  
Stream Model

We subjectively perceive our visual field with high fidelity, yet peripheral distortions can go unnoticed and peripheral objects can be difficult to identify (crowding). Prior work showed that humans could not discriminate images synthesised to match the responses of a mid-level ventral visual stream model when information was averaged in receptive fields with a scaling of about half their retinal eccentricity. This result implicated ventral visual area V2, approximated ‘Bouma’s Law’ of crowding, and has subsequently been interpreted as a link between crowding zones, receptive field scaling, and our perceptual experience. However, this experiment never assessed natural images. We find that humans can easily discriminate real and model-generated images at V2 scaling, requiring scales at least as small as V1 receptive fields to generate metamers. We speculate that explaining why scenes look as they do may require incorporating segmentation and global organisational constraints in addition to local pooling.

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