The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
William H. Wilson - One of the best experts on this subject based on the ideXlab platform.
-
source monitoring deficits for self generated stimuli in schizophrenia multinomial modeling of data from three sources
Schizophrenia Research, 2002Co-Authors: Richard S E Keefe, Miriam C Arnold, Ute J. Bayen, Joseph Patrick Mcevoy, William H. WilsonAbstract:Abstract Introduction : Schizophrenia patients, particularly those with specific types of hallucinations and delusions, may have a deficit in monitoring the generation of thought. This deficit, termed autonoetic Agnosia , may result in the conclusion that self-generated thoughts come from an external source. Methods : This study assessed autonoetic Agnosia in 29 schizophrenic patients and 19 controls by applying a recently developed technique from cognitive science: multinomial modeling of source-monitoring data. Results : Schizophrenic patients demonstrated deficits in monitoring the source of self-generated information, yet performed similarly to controls in monitoring the source of visual and auditory information. Schizophrenic patients with specific “target” symptoms such as auditory hallucinations and thought insertion had greater deficits than other patients in recognizing self-generated information. Conclusion : This study offers partial support for the notion that schizophrenic patients manifest autonoetic Agnosia.
Lynn J Speedie - One of the best experts on this subject based on the ideXlab platform.
-
characteristics of auditory Agnosia in a child with severe traumatic brain injury a case report
Brain and Language, 2005Co-Authors: Nina Hattiangadi, Joseph P Pillion, Beth S Slomine, James R Christensen, Melissa Katrina Trovato, Lynn J SpeedieAbstract:We present a case that is unusual in many respects from other documented incidences of auditory Agnosia, including the mechanism of injury, age of the individual, and location of neurological insult. The clinical presentation is one of disturbance in the perception of spoken language, music, pitch, emotional prosody, and temporal auditory processing in the absence of significant deficits in the comprehension of written language, expressive language production, or peripheral auditory function. Furthermore, the patient demonstrates relatively preserved function in other aspects of audition such as sound localization, voice recognition, and perception of animal noises and environmental sounds. This case study demonstrates that auditory Agnosia is possible following traumatic brain injury in a child, and illustrates the necessity of assessment with a wide variety of auditory stimuli to fully characterize auditory Agnosia in a single individual.
Mohamed Saoud - One of the best experts on this subject based on the ideXlab platform.
-
low frequency repetitive transcranial magnetic stimulation improves source monitoring deficit in hallucinating patients with schizophrenia
Schizophrenia Research, 2006Co-Authors: Jérome Brunelin, Benoit Bediou, Lassad Kallel, Thierry Damato, Emmanuel Poulet, Jean Dalery, Mohamed SaoudAbstract:Auditory hallucinations have been associated with a disruption in monitoring one's own speech suggesting an autonoetic Agnosia in schizophrenia. This deficit can be measured by a source monitoring task. Low frequency transcranial magnetic stimulations (rTMS) applied to the left temporoparietal cortex can inhibit cortical areas involved both in autonoetic Agnosia (which means 'the inability to identify self-generated mental events') and in auditory hallucinations (AH) phenomena. Although improvements in AH have been repeatedly reported following rTMS treatment, effects on autonoetic Agnosia measured by source monitoring have never been investigated. We aimed to investigate the relation between improvements in AH and source monitoring performance after rTMS treatment. Twenty four right-handed refractory schizophrenic patients with hallucinations randomly received sham or active 10.0001-Hz rTMS to the left temporoparietal cortex and performed 2 source monitoring tasks requiring discrimination between silent- and overt-reading words before and after rTMS sessions. Compared to sham, active rTMS significantly improved AH. Source monitoring performances and the improvements tended to correlate, which would support a specific relation between autonoetic Agnosia and auditory hallucinations.
Geoffrey Underwood - One of the best experts on this subject based on the ideXlab platform.
-
2011 special issue modeling eye movements in visual Agnosia with a saliency map approach bottom up guidance or top down strategy
Neural Networks, 2011Co-Authors: Tom Foulsham, Jason J S Barton, Alan Kingstone, Richard Dewhurst, Geoffrey UnderwoodAbstract:Two recent papers (Foulsham, Barton, Kingstone, Dewhurst, & Underwood, 2009; Mannan, Kennard, & Husain, 2009) report that neuropsychological patients with a profound object recognition problem (visual agnosic subjects) show differences from healthy observers in the way their eye movements are controlled when looking at images. The interpretation of these papers is that eye movements can be modeled as the selection of points on a saliency map, and that agnosic subjects show an increased reliance on visual saliency, i.e., brightness and contrast in low-level stimulus features. Here we review this approach and present new data from our own experiments with an agnosic patient that quantifies the relationship between saliency and fixation location. In addition, we consider whether the perceptual difficulties of individual patients might be modeled by selectively weighting the different features involved in a saliency map. Our data indicate that saliency is not always a good predictor of fixation in Agnosia: even for our agnosic subject, as for normal observers, the saliency-fixation relationship varied as a function of the task. This means that top-down processes still have a significant effect on the earliest stages of scanning in the setting of visual Agnosia, indicating severe limitations for the saliency map model. Top-down, active strategies-which are the hallmark of our human visual system-play a vital role in eye movement control, whether we know what we are looking at or not.
-
fixation and saliency during search of natural scenes the case of visual Agnosia
Neuropsychologia, 2009Co-Authors: Tom Foulsham, Jason J S Barton, Alan Kingstone, Richard Dewhurst, Geoffrey UnderwoodAbstract:Models of eye movement control in natural scenes often distinguish between stimulus-driven processes (which guide the eyes to visually salient regions) and those based on task and object knowledge (which depend on expectations or identification of objects and scene gist). In the present investigation, the eye movements of a patient with visual Agnosia were recorded while she searched for objects within photographs of natural scenes and compared to those made by students and age-matched controls. Agnosia is assumed to disrupt the top-down knowledge available in this task, and so may increase the reliance on bottom-up cues. The patient's deficit in object recognition was seen in poor search performance and inefficient scanning. The low-level saliency of target objects had an effect on responses in visual Agnosia, and the most salient region in the scene was more likely to be fixated by the patient than by controls. An analysis of model-predicted saliency at fixation locations indicated a closer match between fixations and low-level saliency in Agnosia than in controls. These findings are discussed in relation to saliency-map models and the balance between high and low-level factors in eye guidance.
Richard S E Keefe - One of the best experts on this subject based on the ideXlab platform.
-
source monitoring deficits for self generated stimuli in schizophrenia multinomial modeling of data from three sources
Schizophrenia Research, 2002Co-Authors: Richard S E Keefe, Miriam C Arnold, Ute J. Bayen, Joseph Patrick Mcevoy, William H. WilsonAbstract:Abstract Introduction : Schizophrenia patients, particularly those with specific types of hallucinations and delusions, may have a deficit in monitoring the generation of thought. This deficit, termed autonoetic Agnosia , may result in the conclusion that self-generated thoughts come from an external source. Methods : This study assessed autonoetic Agnosia in 29 schizophrenic patients and 19 controls by applying a recently developed technique from cognitive science: multinomial modeling of source-monitoring data. Results : Schizophrenic patients demonstrated deficits in monitoring the source of self-generated information, yet performed similarly to controls in monitoring the source of visual and auditory information. Schizophrenic patients with specific “target” symptoms such as auditory hallucinations and thought insertion had greater deficits than other patients in recognizing self-generated information. Conclusion : This study offers partial support for the notion that schizophrenic patients manifest autonoetic Agnosia.
