Capgras Delusion: Impaired Face Recognition Process

Capgras Delusion Impaired Face Recognition ProcessCapgras delusion, the principle that somebody is replaced by an imposer. First, this contemplate examines whether Capgras unhurrieds, comp atomic number 18d to controls, have an impaired exhibit recognition process. Patients draw to be hyporesponsive to well-known(prenominal) governances and specify to have a decreased act in ace areas, such as the prefrontal, asquint pass temporal and mesial temporal regions. The stand by part of this guinea pig examines the doctrine ratiocination processes in forbearings compared to controls. Patients constitute an hinderance in their depression ratiocination process and this is linked to an trauma of the right lateral prefrontal lens mantle.The goal is to see whether Capgras patients have an impaired show-recognition process and an impaired public opinion-evaluating process, associated with the genius activity, compared to control participants.The main objectives demo th at Capgras patients have an impaired face recognition process because they are hyporesponsive to known faces, by measuring response times of the recognition of long- well-known(prenominal) and foreign faces.Showing that, because certain areas in the brain are accountable for face recognition, Capgras patients have impairments in certain brain areas, such as the prefrontal, lateral temporal and mesial temporal regions (by measuring the BOLD activity in these areas), to experience Capgras delusions, because they are hyporesponsive to familiar faces.Showing that, because gibe to Colthearts two component part possibleness, Capgras patients have a decreased reasoning-evaluation process, Capgras patients have an impaired reasoning process. This study excessively wants to show that this reasoning process is associated with the right lateral prefrontal cortex (by measuring the BOLD activity in the right lateral prefrontal cortex) and that Capgras patients should show in impairment in this area.This study is want to expand research on which processes are damaged in people who experience Capgras delusions, looking at two theories. Experiment 1 and 2 are about damage to the face recognition system. In experiment 1we argue that patients are hyporesponsive to familiar faces by looking at their reaction times in the recognition of familiar and unfamiliar faces. In experiment 2, an fMRI scan measures the brain activity spot participants look at familiar and unfamiliar faces. It is predicted that Capgras patients leave alone show impairments in areas that are involved in face recognition, such as the prefrontal, lateral temporal and mesial temporal regions. The second theory, the two pointor theory, suggests that delusions are a result of an impairment of principle evaluation processes. Experiment 3 wants to link this impairment in belief reasoning to the right prefrontal lateral cortex. Capgras patients are swayed to show a decreased activity, measured by an fMRI scan, in this area small-arm they do a belief reasoning task. This will indicate that Capgras patients have impaired face recognition processes and impaired belief reasoning processes and these processes are linked to several impairments in the brain.Delusional misidentification syndromes (DMS) are psychiatric disorders distinguished by the fact that they all involve some deviation from normal processes of recognising people (Ellis Young, 1990, p239). A specific DMS is the Capgras syndrome. The Capgras syndrome is characterized by the patient insisting that others, usually those quite close emotionally, have been replaced by doubles, impostors or robots (Ellis et al., 1997, p 1058). For example, a bit could think his mother is replaced by an imposer. Mostly the duplicated people, are people very close to the patients (Todd et al., 1981) and the patients often show conflicting feelings of love and hate for the duplicated relatives (Enoch Trethowan, 1991). Most of the patien ts who are low from Capgras syndrome have some evidence of brain abnormalities (Joseph, 1985).Bauer (1984, 1986) introduced the dual recognition route. He suggests that there are two routes of facial recognition, the dorsoventral and the dorsal route. The ventral route runs from the visual cortex to the temporal lobes and is the conscious recognition route. The dorsal route runs from the visual cortex to the limbic system and is the affective response route. Ellis Young (1990) proposed that Capgras delusion is a mirror- characterisation of prosopagnosia, the inability to recognise foregoing familiar faces, mostly following brain damage (Sorger et al., 2007). They suggested that in Capgras delusions, the affective response route is damaged, which bureau that patients will consciously recognise the person, but they wont have an affective response that is associated with familiarity, but they do have an intact ventral route. In 1997 Ellis et al. did study on face recognition in Ca pgras patients. They base that unlike the control participants, who showed significant departures, that Capgras patients showed no difference in skin conductance response (SCR) to familiar and unfamiliar faces, which means that they are hyporesponsive to familiar faces and thus that Capgras patients have a breakdown in familiarity processing. Coltheart (2007) worked further on this idea and proposed that if you can answer the next two questions, we can have a possible comment for the delusion. Where did the delusion come from? and Why does the patient not reject the belief? (Coltheart, 2007, p1044). This called this the two factor theory of delusions. He proposed that there had to be two neuropsychological deficits. First, what is responsible for the content of the delusion and secondly, what is responsible for the continuity of the belief, which means that there needs to be damage in the right hemisphere, because it is involved in belief evaluation. They argued that the right t emporal-parietal regions and the right frontal lobe are very important in the belief evaluation. In 2011, Coltheart et al. explained that via abductive conclusion we make propositions. These propositions have to survive a belief-evaluation process to be adopted as a belief. agree to Coltheart et al. (2011) this belief evaluation process is damaged in Capgras patients.This study wants to look at both views, the impairments of face recognition and the impairments to belief evaluation processes.Experiment 1 and 2 focuses on face recognition, whether experiment 3 focuses on the belief evaluation process. First of all, usually reaction times are significantly hot for familiar faces than for unfamiliar faces (Balas, cox Conwell, 2007). Because of the hyporesponsiveness to familiar faces (Ellis et al., 1997), Capgras patients are expected to have no significant difference in reaction time between familiar and unfamiliar faces. Secondly, according to Ellis et al. (1997), Capgras patien ts should have an impairment in their face recognition. One study found a reduced neural activity in the face recognition system in a case of Capgras delusion (Thiel et al., 2013). Another study found high activity in the left superior parietal and biletral middle frontal gyrus in familiar faces (Rossion et al., 2001). Activations in the prefrontal, lateral temporal and mesial temporal regions were associated with recognition of famous faces (Leveroni et al., 2000). This would mean that Capgras patients, who are hyporesponsive to familiar faces (Ellis et al., 1997), would show an increased activity in these areas. In experiment 3, the belief evaluation process is tested. Coltheart et al. (2011) suggested that the impairment in Capgras patients in the belief evaluation process is associated with right lateral prefrontal cortex pathology. turn out was found for a dynamic neural system for reasoning in the lateral/dorsal lateral prefrontal cortex (Goel Dolan, 2003). In an fMRI study , they found a role of the lateral prefrontal cortex in modulation of reasoning by beliefs (Goel Dolan, 2003). They found that correct logical reasoning showed an increased activity in the right lateral prefrontal cortex. This means that, according to Colthearts two factor theory (2010), that Capgras patient would show a decreased activity in this area, because of their impairments in the belief evaluation system.Participants and designThis study will recruit a sample of 10 Capgras patients and 10 healthy age-matched controls. Participants will receive fees for participating. They will be provided with an informed consent. This study exists out of two experiments. In the first task participants will be provided with pictures of familiar and unfamiliar faces (in Capgras patients familiar faces of the persons they replace with imposers and in controls with family members) while reaction time is measured and an fMRI scan is taken. In the second experiment, the right lateral prefrontal cortex activity is measured with an fMRI scan while the participants look at familiar and unfamiliar faces and at the alike time are asked questions about these persons in a belief-reasoning task.Stimulus materials and procedureIn the first experiment, participants were asked to sit in 0.5 m in front of a screen. Each trial started with a cue image of a familiar or an unfamiliar face for 500 ms. After an interinterval of 500 ms, a picture that matched the cue image was shown together with a picture that didnt match (left and right). The participants were asked via button presses to show which picture matched the cue image, as rapid and accurately as possible. All stimulus presentation responeses were analysed with the Matlab Psychophysics Tool concussion. This task was taken from Balas, Cox Conwell (2007).In the second experiment, before the participants will be asked to enter the fMRI, they will be instructed about the task. This study uses the task Ellis et al. (1997) used, fo r examen the identification of familiar faces. When they are in the fMRI, they will see pictures of their family members (for the Capgras patients, including the persons they think are replaced by imposers) or unfamiliar pictures. They got to see 10 familiar faces and 20 unfamiliar faces in random order. For each face the participant was asked to respond if the face was familiar to them or not, while the fMRI scan measured their blood-oxygen-level babelike (BOLD) activity in their brain. In experiment 3, the participants were asked again to enter the fMRI scan. We used the belief reasoning task (Appendix Picture 1) of Sommer et al. (2007). In both of the conditions, the first four pictures are the same. In the true belief task the girl comes back in the room and sees that the boy puts the ball into the basket. In the false belief task, she comes back in the room after he putted the ball in the basket. The response picture (red) was the same in both condition. In 50% of the trials, the girl, based on her belief, looked for the ball in the expected box and in the other 50% in the unexpected box. The participants needed to decide if Betty, based on her belief, make the expected or unexpected choice by key pressing, while the BOLD activity in the right lateral prefrontal cortex was measured.In experiment 1 we expect that Capgras patients will show no significant difference in reaction times to familiar or unfamiliar faces, because of their hyporesponsivess to familiar faces (Ellis et al., 1997), compared to normal controls who are expected to have reaction times faster for familiar faces than for unfamiliar faces (Balas, Cox Conwell, 2007). In experiment 2 we expect Capgras patients to have a decreased activity in the prefrontal, lateral temporal and mesial temporal regions compared to controls, because of their impairment in face recognition (Ellis et al., 1997). In experiment 3, we expect patients to have a decreased activity in the right lateral prefrontal c ortex while they do the belief reasoning task, because of Colthearts suggestion that Capgras patients have a damaged belief evaluation process.This study will benefit psychologist who have studied Capgras delusion, because the causes are still very vague and not that numerous studies have been done on Capgras. It will also benefit Capgras patients. . It can be useful for patients suffering from schizophrenia and dementia because Capgras syndrome is often associated with these disorders. It can help create treatments by knowing the origins in the brain while patients experience these hallucinations. This study focus on more theories, which makes it easier to understand this delusion.