Biomedical subjects

Shelley Channon

Publications and source records attributed to Shelley Channon.

16 recordsLinked to original sources

PubMed2006

Humor processing, mentalizing, and executive function in normal aging.

Recent investigations have emphasized the importance of the prefrontal cortex for humor processing. Although the prefrontal cortex is thought to be affected by normal aging, relatively little work has been carried out to investigate the effects of aging on humor processing. In the present investigation participants in three age groups were assessed on a humor comprehension task. They then answered mentalistic and nonmentalistic questions. Executive tasks were also administered. The older group selected significantly fewer correct punchlines from alternatives than the other groups. They were also poorer at answering mentalistic questions, but did not differ significantly for nonmentalistic questions. The findings of the present investigation showed altered in humor processing in normal aging, and this appeared to be related to mentalizing ability.

Adult↗

PubMed2006

The case for the development and use of "ecologically valid" measures of executive function in experimental and clinical neuropsychology.

This article considers the scientific process whereby new and better clinical tests of executive function might be developed, and what form they might take. We argue that many of the traditional tests of executive function most commonly in use (e.g., the Wisconsin Card Sorting Test; Stroop) are adaptations of procedures that emerged almost coincidentally from conceptual and experimental frameworks far removed from those currently in favour, and that the prolongation of their use has been encouraged by a sustained period of concentration on "construct-driven" experimentation in neuropsychology. This resulted from the special theoretical demands made by the field of executive function, but was not a necessary consequence, and may not even have been a useful one. Whilst useful, these tests may not therefore be optimal for their purpose. We consider as an alternative approach a function-led development programme which in principle could yield tasks better suited to the concerns of the clinician because of the transparency afforded by increased "representativeness" and "generalisability." We further argue that the requirement of such a programme to represent the interaction between the individual and situational context might also provide useful constraints for purely experimental investigations. We provide an example of such a programme with reference to the Multiple Errands and Six Element tests.

Cognition Disorders↗

PubMed2006

Tourette's syndrome (TS): cognitive performance in adults with uncomplicated TS.

Tourette's syndrome (TS) is a neurodevelopmental disorder associated with frontostriatal dysfunction. The extent of any cognitive impairment associated with uncomplicated TS is unclear, as comorbid psychiatric symptomatology is thought to contribute to cognitive deficits. Previous studies have found evidence of mild performance deficits, most commonly on tasks that involve inhibitory processes. The present study evaluated this in carefully screened adult participants with TS. The findings showed the TS group to perform more poorly on one test involving behavioral inhibition (sentence completion), but did not provide strong support for an interpretation based solely on inhibitory deficits, and there was no evidence of impairment on another behavioral inhibition task (flanker test). There were also no differences between the groups on tasks involving working memory (n-back), task switching, or object alternation learning. The findings provide further evidence that uncomplicated TS is associated with only mild, circumscribed impairment. The nature of any impairment is discussed.

Adult↗

PubMed2005

Disruption of sequential priming in organic and pharmacological amnesia: a role for the medial temporal lobes in implicit contextual learning.

We examined learning and expression of contextual implicit learning of a sequence of targets in a speeded target-detection task in amnesic and control participants. Amnesia was of organic origin in one participant group and induced psychopharmacologically (diazepam 7.5 or 15 mg) in another. Although the amnesic groups were able to learn the target sequence normally, their expression of sequence knowledge (priming) was attenuated when contextual support was limited. This was evaluated by studying response latencies for targets primed by between 0 and 5 preceding context locations. Whereas control participants showed priming when the current target location was primed by only two previous locations, priming was eliminated with two (but not four) previous locations by a low dose of diazepam and was eliminated even with four elements of context under a high dose of diazepam and in amnesia of organic origin. The results suggest that a function of the hippocampal memory system is to support contextual learning and performance, even when that learning is nondeclarative.

Adolescent↗

PubMed2005

Social cognition after head injury: sarcasm and theory of mind.

Closed head injury (CHI) is associated with communication difficulties in everyday social interactions. Previous work has reported impaired comprehension of sarcasm, using sarcastic remarks where the intended meaning is the opposite of the sincere or literal meaning. Participants with CHI in the present study were assessed using two types of sarcastic items, those with a directly opposite meaning and those with an indirect, non-literal but not directly opposite meaning. The CHI group was differentially poorer at comprehending sarcastic versus sincere remarks, although type of sarcastic materials did not influence performance. Errors involved not only literal interpretations, but also incorrect non-literal interpretations. Theory of mind (mentalising) was also assessed by comparing comprehension of human actions with control physical events. The CHI group was selectively impaired on the mentalising component of this task, and mentalising scores correlated with sarcasm comprehension. The implications of the findings for our understanding of impaired sarcastic comprehension after acquired brain injury are discussed.

Adolescent↗

PubMed2005

Executive functioning and speed of processing in phenylketonuria.

Treated phenylketonuria (PKU) has been linked to dopaminergic depletion in the dorsolateral prefrontal cortex, potentially leading to selective executive impairment. White matter abnormalities may lead to generalized slowing of information processing. These 2 hypotheses were evaluated in adults with PKU on a lifelong diet. Those with PKU were significantly slower than the control group regardless of working memory load on an n-back task and marginally slower regardless of trial type (inhibitory or noninhibitory) on a flanker task. There were no significant differences in speed on object alternation learning or perceptual judgment tasks. There were no group differences in accuracy on any task. These findings do not appear consistent with the selective executive hypothesis. A cognitive slowing account may prove more informative in adults with PKU, but more evidence is needed. The findings suggest that continuous dietary management is a fairly successful strategy in terms of cognitive outcome for adults.

Adolescent↗

PubMed2005

Tourette's syndrome: performance on tests of behavioural inhibition, working memory and gambling.

BACKGROUND: Tourette's syndrome (TS) is a neurodevelopmental disorder associated with fronto-striatal dysfunction. There is debate as to the extent to which TS is associated with cognitive impairment. Some authors argue that any impairments seen are attributable to comorbid psychiatric symptomatology, whilst others have suggested that uncomplicated TS is associated with mild deficits limited primarily to inhibitory processes. The present study was designed to examine this issue using carefully screened participants with TS and experimental measures thought to involve different areas of the frontal lobes. METHODS: Adolescents with TS who were screened for comorbid psychiatric disorder were compared with a healthy control group on a set of executive measures. Two tasks involving behavioural inhibition were used: a Sentence Completion task in which sentences had to be completed first with straightforward and then with nonsensical endings, and a Flanker task in which a central stimulus was surrounded by either compatible or incompatible flankers. Working memory was assessed using an N-back task, and reward learning was assessed using a Gambling task. Both accuracy and reaction times were measured for each task. RESULTS: The TS group differed significantly from the control group on both the Sentence Completion task and on the Flanker task. On the Sentence Completion task, they were slower to make both sensible and nonsensical completions, and they had higher error scores on the nonsensical completions. On the Flanker task, the TS participants were less accurate than the control group, since they were poorer on the incompatible but not the compatible trials. A similar interaction with trial type was found for speed, where the TS participants were slowed more by the incompatible versus compatible trials, although overall their performance tended to be faster than the controls. The TS group did not differ significantly from the control group on measures of working memory or reward learning. CONCLUSIONS: The findings provide further evidence that uncomplicated TS is not associated with widespread executive impairments. However, it was not clear that any differences between the groups could be attributed solely to selective inhibitory impairment.

Adolescent↗

PubMed2004

Social cognition in Tourette's syndrome: intact theory of mind and impaired inhibitory functioning.

Although associations between social cognition involving theory of mind and non-social executive skills have frequently been reported, dissociations in performance have also been found. The present study was designed to examine social and non-social cognition in uncomplicated Tourette Syndrome (TS). Adult TS participants without comorbid diagnoses were compared to matched healthy control participants on social cognition measures involving theory of mind and empathy, and on non-social executive tasks. Participants with TS were found to make more errors than a matched control group on an inhibitory task, but did not differ on other executive measures or on the social cognition measures. The implications of the findings for our understanding of TS and of the relationship between social cognition and executive skills are discussed.

Adolescent↗

PubMed2004

Executive functioning, memory, and learning in phenylketonuria.

The executive deficit hypothesis of treated phenylketonuria (PKU) suggests that dopaminergic depletion in the lateral prefrontal cortex leads to selective executive impairment. This was examined by comparing adults with PKU on a lifelong diet with a matched healthy control group. Those with PKU were impaired on selective and sustained attention, working memory (Self-Ordered Pointing), and letter fluency. However, they failed to show differential sensitivity to increased cognitive load on the attentional and working memory tasks, and they did not differ significantly on the remaining executive tasks (rule finding, inhibition, and multitasking). Nor did they differ significantly on recall or recognition memory. Overall, the findings provided little support for the executive deficit hypothesis. A possible explanation in terms of slowed information processing speed is explored.

Adolescent↗

PubMed2003

Relationship between priming and recognition in deterministic and probabilistic sequence learning.

Exposure to a repeating sequence of target stimuli in a speeded localization task can support both priming of sequence-consistent responses and recognition of sequence components. In 3 experiments with both deterministic and probabilistic sequences, the authors used a novel procedure in which measures or priming and recognition were taken concurrently and asked whether these measures can be dissociated. In all of these experiments, both measures were above chance at the group level and no evidence of dissociation was found. Item-level analyses of the data in Experiment 3 did reveal dissociations in that (a) recognition judgments were affected by response speed independently of old-new status and (b) items that were not discriminated in recognition nonetheless showed priming. However, the authors show that these data, together with the group-level results, are compatible with a formal model in which priming and recognition are based on a single common memory variable.

Adolescent↗

PubMed2003

Executive function, memory, and learning in Tourette's syndrome.

Young people with Tourette's syndrome (TS) alone, TS plus attention-deficit/hyperactivity disorder (+ADHD), or TS plus obsessive-compulsive disorder (+OCD) were compared with a healthy control group on a set of measures of executive functioning, memory, and learning. The TS-alone group was impaired on one executive measure involving inhibition and strategy generation but did not differ significantly from the healthy control group on other measures. The TS+ADHD group showed impairment on several executive measures. There was no evidence of impairment in implicit aspects of memory and learning for any of the TS groups. The findings are discussed in terms of the frontostriatal hypothesis of TS and the contribution of comorbid symptomatology.

Adolescent↗

PubMed2003

Pragmatic language interpretation after closed head injury: relationship to executive functioning.

INTRODUCTION: Closed head injury is associated with impairment in a range of executive skills, and with everyday difficulties in social interactions. Comprehension of pragmatic language plays an important role in social interactions. The present study was designed to examine performance on a task involving pragmatic judgement in people who had suffered closed head injury (CHI), and the relationship between this and any impairments in executive skills. METHODS: Participants with CHI were compared to a matched healthy control group on a pragmatic inference task consisting of a series of brief vignettes. Participants made judgements about alternative responses in relation to social appropriateness/skill, and carried out several nonsocial executive tasks thought to play a role in pragmatic judgement. RESULTS: The CHI group was poorer than the control group on the pragmatic measure, showing less discrimination than the control group between direct, literal interpretations and correct, indirect interpretations. They also performed more poorly on the nonsocial executive measures. Regression analysis showed an association between pragmatic performance and one of the executive tasks, a measure of inhibition. CONCLUSIONS: More work is needed to explore further the nature of any relationship between pragmatic judgement and executive skills.

Journal Article↗

PubMed2003

Real-life-type problem solving in Tourette syndrome.

OBJECTIVE: The main objective of the study was to examine social problem solving in real-life-type situations in Tourette syndrome (TS). BACKGROUND: Studies of cognitive functioning in TS have usually focused on nonsocial, abstract tasks, with mixed findings as to whether there is evidence of impairment in executive functions in those without comorbid disorders. The current study focuses primarily on social functioning, using a problem-solving task known to be sensitive to frontal lobe lesions. METHODS: TS participants without comorbid diagnoses were compared with matched healthy control participants on a problem-solving task, using a range of interpersonal problem scenarios presented on video. A set of more abstract executive tests was also included. RESULTS: Participants with TS were found to perform below a matched control group on the problem-solving task both in generating a range of potential problem solutions, and in selecting appropriate final solutions. They also performed more poorly on aspects of executive function. CONCLUSIONS: This study provides evidence of difficulties in both social and nonsocial aspects of functioning in TS. The implications of the findings for our understanding of TS and problem solving are discussed.

Adult↗

PubMed2002

Effects of a secondary task on "implicit" sequence learning: learning or performance?

Traditionally, implicit learning has been defined in terms of a lack of awareness of the process and products of learning. In the face of a number of conceptual and empirical difficulties with this definition, it has recently been suggested instead that the critical feature of implicit learning is that it proceeds without making any demands on attentional resources. As disconfirmatory evidence for this, we describe the results of two experiments which each used a sequential reaction time task. With a tone-counting secondary task, measures of sequence learning were significantly affected by whether training occurred under single- or dual-task conditions, regardless of whether testing took place under single- or dual-task conditions.

Adult↗

PubMed2002

Is implicit learning spared in amnesia? Rule abstraction and item familiarity in artificial grammar learning.

We examined implicit learning of an artificial grammar in amnesic and control participants. The "biconditional" grammar used to generate study and test strings allows two potential sources of judgements in artificial grammar learning to be unconfounded: participants could either learn the abstract biconditional rules or could learn about the distributional statistics of the surface elements (e.g. bigrams) composing the study items. Test strings varied these two sources orthogonally. We found no evidence of abstract rule learning either in the control or amnesic groups. In contrast, both groups learned about the surface elements and tended to call test strings "grammatical" when they were composed of familiar bigrams. However, this sensitivity to bigram familiarity was significantly reduced in the amnesic compared to the control group. The results challenge the claim that implicit learning is intact in amnesia.

Amnesia↗

PubMedDate not supplied

Frontal lobe dysfunction and everyday problem-solving: social and non-social contributions.

Everyday problem-solving involves both non-social executive processes, social and emotional processes, and draws upon social and practical knowledge. A series of studies including both adult-acquired lesions and neurodevelopmental disorders is reviewed examining problem-solving on a real-life-type task that involves generating a range of solutions to brief problem scenarios and selecting preferred solutions to solve the problems. Impairments in problem-solving are described in groups of participants with left anterior frontal lobe lesions, Tourette's syndrome and Asperger's syndrome. By contrast, healthy older people did not show problem-solving deficits on the same task. The possible contributions of non-social executive skills, social and emotional skills, and knowledge acquired from experience are each considered in relation to everyday performance. Multiple cognitive/emotional routes to the development of everyday life difficulties pose a complex challenge both in understanding the nature of the relevant processes and in developing adequate methods for management and rehabilitation.

Adolescent↗