Does autonomic arousal distinguish good and bad decisions? Healthy individuals’ skin conductance reactivity during the Iowa Gambling Task

Original article can be found at: http://psycontent.metapress.com/ Copyright Hogrefe & HuberThe Somatic Marker Hypothesis (SMH) proposes that physiological feedback to the brain influences cognitive appraisal and decision-making; however, the strength of evidence in support of the SMH is equivocal. In this study we examined the validity of the SMH by measuring physiological arousal in a population of healthy individuals playing the Iowa Gambling Task (IGT); a computerised card game designed to assess real-life decisionmaking. We also aimed to clarify uncertainty regarding the influence of reinforcer type and impulsiveness to IGT performance and the SMH. Skin conductance level (SCL) and heart rate reactivity were measured in forty-one participants performing the IGT using either facsimile or real money. Participants were categorised as non-impaired or impaired on the basis of their IGT performance, and any differences in performance and physiological between groups were examined. Heart rate data did not reveal any effects. Robust differences in SCL reactivity during the task were not found between impaired and nonimpaired individuals; however, marginal SCL rises were observed when non-impaired individuals anticipated and received a reward from disadvantageous choices compared with advantageous ones. This effect was found only when using facsimile money and did not occur in impaired individuals, suggesting some effect of reinforcer type on physiological activity and performance, and a difference in the physiology of impaired and non-impaired individuals. No significant differences in impulsiveness were found between impaired and non-impaired individuals. The findings suggest that autonomic activity is independent of long-term good or bad decision-making, and may reflect differences between decks in the magnitude of gain and loss. It is concluded that further substantiating evidence is needed for the SMH to continue as an explanation for human decision-making.Peer reviewe

An investigation of conscious recollection, false recognition and delusional misidentification in patients with schizophrenia

Background: Recognition memory (RM) is impaired in patients with schizophrenia, as they rely largely on feelings of familiarity rather than conscious recollection. It has been suggested that this abnormality may reflect a breakdown in strategic memory processes involved in both encoding and retrieval. By studying 2 patients with false recognition (FR; patient C.T.) and delusional misidentification (DM; patient B.C.), and a group of psychotic control patients, we examined proposals that FR and DM exist on a continuum of increasingly severe impairment in strategic memory function. Methods: Executive function, autobiographical memory and verbal and facial RM were assessed using standard neuropsychological tests and the remember/know paradigm. Results: The psychotic control group displayed a significantly reduced reliance on remember judgements and compensatory elevation in know judgements on both RM tasks compared with the normal control group. Patient B.C. also followed this trend, but in a much more pronounced manner. In contrast, patient C.T. displayed a qualitatively different performance profile, which was marked by an increased dependence on remember responses. Conclusions: We have presented evidence which support proposals that a breakdown in strategic memory and executive dysfunction are more pronounced in DM than FR. However, the small sample size precludes any firm conclusions being drawn

Auditory recognition memory in schizophrenia using the remember/know paradigm

Aims: Auditory recognition memory was investigated in Schizophrenia in terms of remember (i.e. specific recollection) and know (i.e. familiarity without specific recollection) judgements. Methods: Three groups were investigated: normal controls (N=21) and patients diagnosed with Schizophrenia (N=10) and Major Depressive Disorder, Recurrent (N=10) according to DSM IV criteria. Participants were required to discriminate between previously heard sentences (targets) and novel sentences (distracters). Results: Results were analysed in terms of hit-rate frequency (number of correct targets), false-alarm rate frequency (number of false alarms), and signal-detection measures of A' (ability to discriminate between targets and distracters), and B''D (response bias i.e. probability of accepting a stimulus as a target when uncertain). Non-parametric tests showed no significant differences for hit-rate frequency, false-alarm rate frequency, A', and B''D. However, significant differences in remember (P<0.001) and know (P<0.05) were found. Patients with Schizophrenia made significantly more know judgements relative to normal controls (P<0.01) and significantly fewer remember judgements relative to normal controls (P<0.001) and patients with Major Depressive Disorder, Recurrent (P<0.01). Conclusions: Evidence suggests that amongst the reported cohort of patients with Schizophrenia; remember judgements play a significantly reduced contribution to auditory recognition memory compared to normal controls and patients with Major Depressive Disorder, Recurrent

Reality monitoring in anosognosia for hemiplegia

Anosognosia for hemiplegia (AHP) is a lack of awareness about paralysis following stroke. Recent explanations use a ‘forward model’ of movement to suggest that AHP patients fail to register discrepancies between internally- and externally-generated sensory information. We predicted that this failure would impair the ability to recall from memory whether information is internally- or externally-generated (i.e., reality monitor). Two experiments examined this prediction. Experiment 1 demonstrated that AHP patients exhibit a reality monitoring deficit for non-motor information (i.e., perceived vs. imagined drawings), whilst hemiplegic controls without anosognosia (nonAHP) perform like age-matched healthy volunteers (HVs). Experiment 2 explored if this deficit occurs when AHP patients discriminate performed, imagined, or observed movement. Results showed impaired reality monitoring for movements in AHP and nonAHP patients relative to HVs. Findings suggest that reality monitoring processes not directly related to movement, together with a failure to reality monitor movements, contribute to the pathogenesis of AHP

Расчет кривых течения сплавов алюминия на основе моделей дислокационной кинетики сдвигов и накопления повреждений в ходе их пластического деформирования

'This is an author-created, un-copyedited version of an article accepted for publication in Behavioural Neurology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at http://iospress.metapress.com/'Anosognosia for hemiplegia (AHP) refers to a lack of awareness regarding paralysis after stroke. Despite attracting clinical interest for decades, empirical research into AHP has been relatively scarce, and there remains no universally accepted explanation (Jenkinson & Fotopoulou, 2010). This is partially due to difficulty characterising the disorder. The term has been applied to both partial and complete lack of awareness, with partial unawareness presenting as a failure to recognise, appreciate the severity, or acknowledge the consequences of paralysis, and more complete cases involving a failure to admit the presence of a paralysis even after its demonstration (Orfei et al., 2007). The fact that some patients verbally deny their problems, but show behaviours consistent with their paralysis (e.g. executing a bimanual tasks using a unimanual strategy), while others verbally accept their paralysis but behave in a manner inconsistent with this acceptance (e.g. attempting to walk), suggests that verbal and behavioural awareness are independent (Jehkonen et al., 2006). The observation of diverse lesion sites, emotional, perceptual, and cognitive impairments in anosognosia has also resulted in unawareness being considered a multifaceted or multicomponent disorder involving several subtypes (Jehkonen et al., 2006, Orfei et al., 2007, Vocat & Vuilleumier, 2010). As such, different forms of anosognosia may reflect the combination of various deficits, the exact components of which are not currently known (Vocat & Vuilleumier, 2010).Peer reviewe

Visual object processing, reality monitoring, reasoning and visual hallucinations in Parkinson's disease

Up to 40% of patients with Parkinson’s disease will develop visual hallucinations at some point in their illness. Although medication, depression, duration of illness, and peripheral visual impairment have been identified as risk factors for hallucinations, more specific changes in cognitive function may also play a role. This pilot study evaluated 9 PD patients with visual hallucinations and 9 nonvisually-hallucinating PD patients on tests of imagery, recognition of objects, reasoning processes and reality monitoring. The reasoning processes tapped ability to derive a set of rules based on feedback, application of a strategy in relation to goal attainment and concept formation. Reality monitoring is defined as the normal process by which perceived and imagined events are discriminated in memory. In healthy volunteers, memories originating from experienced events have more contextual, perceptual and meaningful information than memories derived from internally generated events such as imagery processes, dreams and fantasies. However, if perceptual qualities of imagined events are unusually vivid, they may be more difficult to discriminate from perceived events. Our research revealed that visually hallucinating PD patients have greater difficulty with recognising visual objects viewed as either silhouettes (U=20.00, p=0.07) or when key identifying information which is hidden from view (U=22.00, p=0.05). Reasoning and reality monitoring processes were also deficient (both U=15.00, p=0.02). Errors in the reality monitoring task where most likely to occur for imagined items which were misattributed to perceived items. In contrast spatial processing, spatial imagery and visual object imagery showed higher levels of preservation. The findings from this study raise the possibility that visual hallucinations in PD could stem from a combination of impairments in visual object processing, particularly when key visual attributes of an item are obscured, reasoning and reality monitoring processes. Acknowledgements This work was supported by a Fasttrack grant from the Parkinson’s Disease Society