Biomedical subjects

John G Kerns

Publications and source records attributed to John G Kerns.

11 recordsLinked to original sources

PubMed2007

Experimental manipulation of cognitive control processes causes an increase in communication disturbances in healthy volunteers.

BACKGROUND: Although communication disturbances (CD) have been associated with poor cognitive control, it is unclear whether they are associated specifically with poor cognitive control or with poor cognition in general. The current research examined whether (a) two specific components of cognitive control, working memory and interference resolution, were associated with CD, and (b) associations between CD and cognitive control could be accounted for by generalized poor cognitive performance. METHOD: In this study, as healthy volunteers spoke, the level of cognitive demands was experimentally increased, thereby simulating cognitive deficits (i.e. a reduction in the degree to which certain types of cognitive processes could be used for speech). Hence, this research examined whether simulated cognitive deficits would cause an increase in CD. Participants also completed separate cognitive tasks that assessed working memory, interference resolution and general cognitive ability. RESULTS: An increase in working memory demands caused an increase in CD. Moreover, working memory demands interacted with interference resolution demands, with the greatest amount of CD caused by both high working memory and high interference resolution demands. By contrast, increasing another cognitive demand, sustained attention, did not increase CD. Furthermore, performance on separate working memory and interference resolution tasks interacted to predict CD on the experimental speech task. However, performance on a psychometrically matched cognitive task did not predict CD. CONCLUSION: Overall, the current study provides evidence that working memory and interference resolution may be specifically associated with CD and that manipulations of these cognitive control processes can cause an increase in CD.

Adolescent↗

PubMed2006

Anterior cingulate and prefrontal cortex activity in an FMRI study of trial-to-trial adjustments on the Simon task.

People alter their task performance on a trial-to-trial basis, for example after an incongruent trial on tasks involving response conflict. Previous research has found that these adjustments are most robust in the Simon task. One explanation for behavioral adjustments is the conflict-monitoring hypothesis, which posits that the dorsal anterior cingulate cortex (ACC) responds to conflict and that this serves as a signal to recruit other brain regions such as the prefrontal cortex (PFC) to minimize conflict and improve performance. However, another independently supported explanation for behavioral adjustments on the Simon task is the feature integration view, which can account for behavioral adjustments as the result of stimulus repetitions and alternations. Hence, by itself, evidence for behavioral adjustments on the Simon task does not clearly provide evidence for the conflict-monitoring hypothesis. However, the conflict-monitoring hypothesis does predict that behavioral adjustments on the Simon task should involve ACC conflict activity and PFC post-conflict activity. In the current study, consistent with the conflict-monitoring hypothesis, behavioral adjustments in performance on the Simon task were predicted by ACC conflict-related activity. In addition, subsequent behavioral adjustments were associated with PFC activity, with previous trial ACC conflict-related activity predicting greater PFC activity on subsequent trials. These results provide additional evidence that behavioral adjustments on the Simon task are due in part to ACC conflict monitoring and the subsequent recruitment of PFC to minimize conflict.

Adolescent↗

PubMed2006

Schizotypy facets, cognitive control, and emotion.

This research examined whether facets of schizotypy were differentially related to cognitive control and emotion-processing traits. In a confirmatory factor analysis (N = 261), a 3-factor model of schizotypy exhibited good fit and fit significantly better than a 2-factor model. In addition, only disorganized schizotypy was associated with poor cognitive control (specifically, prepotent inhibition). Moreover, disorganized but not positive schizotypy was associated with increased emotional confusion and increased emotionality. In contrast, negative schizotypy was associated with increased emotional confusion but decreased emotionality. These results suggest that disorganized schizotypy is related to dysregulation of both cognition and emotion and that negative schizotypy might reflect deficits in the experience and processing of emotion and not just in emotional expression.

Adolescent↗

PubMed2005

Positive schizotypy and emotion processing.

This study examined whether emotion processing traits and task performance are associated with positive schizotypy. Positive schizotypy individuals (n=34, assessed with the Magical Ideation and Perceptual Aberration Scales) reported greater attention to emotions but less emotional clarity than controls (n=56). Moreover, a significantly larger percentage of the schizotypy group was classified as emotionally overwhelmed. Positive schizotypy individuals also exhibited absent affective priming and increased incongruent errors at a short stimulus onset asynchrony and an absence of an effect of emotion on recognition memory, but an increased memory response bias for negative words. Results could not be accounted for by level of neuroticism or current mood. These results suggest that positive schizotypy is associated with the processing of emotional information.

Adolescent↗

PubMed2005

Decreased conflict- and error-related activity in the anterior cingulate cortex in subjects with schizophrenia.

OBJECTIVE: People with schizophrenia have exhibited reduced functional activity in the anterior cingulate cortex during the performance of many types of cognitive tasks and during the commission of errors. According to conflict theory, the anterior cingulate cortex is involved in the monitoring of response conflict, acting as a signal for a need for greater cognitive control. This study examined whether impaired conflict monitoring in people with schizophrenia could underlie reduced anterior cingulate activity during both correct task performance and error-related activity. METHOD: Functional activity in the anterior cingulate of 13 schizophrenia patients and 13 healthy comparison subjects was investigated by using event-related fMRI and a Stroop task that allowed simultaneous examination of activity during both conflict (incongruent trials) and error (commission of error trials). RESULTS: In the presence of comparable reaction time measures for conflict as well as comparable error rates, the schizophrenia subjects showed both decreased conflict- and error-related activity in the same region of the anterior cingulate cortex. Moreover, those with schizophrenia did not exhibit significant post-conflict or post-error behavioral adjustments. CONCLUSIONS: Concurrently reduced conflict- and error-related activity in the anterior cingulate cortex along with reduced trial-to-trial adjustments in performance has not previously been reported in schizophrenia. The current results suggest that impaired conflict monitoring by the anterior cingulate cortex might play an important role in contributing to cognitive control deficits in patients with schizophrenia.

Adult↗

PubMed2005

Specificity of prefrontal dysfunction and context processing deficits to schizophrenia in never-medicated patients with first-episode psychosis.

OBJECTIVE: Context processing is a cognitive construct associated with activity in the middle frontal gyrus. Schizophrenia-related deficits in context processing tasks have been associated with prefrontal cortical dysfunction. This study evaluated whether prefrontal cortical dysfunction related to context processing occurred in first-episode, never-medicated schizophrenia patients, whether this dysfunction also occurred in patients with nonschizophrenia psychosis, and whether this dysfunction was related to psychotic symptom expression. METHOD: A modified version of the AX continuous performance task was conducted during event-related functional magnetic resonance imaging in 18 never-medicated, first-episode schizophrenia patients, 12 never-medicated patients with first-episode nonschizophrenia psychosis, and 28 comparison participants without psychiatric disorder. RESULTS: In-scanner measures of errors and interference reaction time showed that the schizophrenia patients had a specific deficit in context processing. Trials with greater context processing demands corresponded to activity in the middle frontal gyrus (Brodmann's area 9) in the comparison subjects and in the patients with nonschizophrenia psychosis, but not in the schizophrenia patients. Individual differences in prefrontal cortical dysfunction were associated with context processing measures and disorganization symptoms. The schizophrenia patients also showed increased activity in the anterior (Brodmann's area 10) and inferior prefrontal cortices (Brodmann's area 45/46) when they were maintaining context over a delay. CONCLUSIONS: Prefrontal dysfunctions related to context processing were found only in schizophrenia patients early in the course of the illness, and these dysfunctions were related to disorganization symptoms. Instead of using context processing during a continuous performance task, schizophrenia patients may use an inefficient encoding and retrieval strategy.

Adult↗

PubMed2004

Prefrontal cortex guides context-appropriate responding during language production.

Although language processing is thought to frequently require cognitive control, little is known about the cognitive and neural basis of the control of language. Here, we demonstrate that processing of context by the PFC plays an important role in the control of language comprehension and production. Using a missing letter paradigm and fMRI, we found that increased activation in the PFC (but not in posterior regions), while encoding and maintaining context information, predicted context-appropriate responses. Furthermore, greater selection demands increased activity during responding in the same regions engaged during the encoding and maintenance of context. Overall, as in other cognitive task domains, these results suggest that PFC context processing plays an important role in the control of language.

Adult↗

PubMed2004

Anterior cingulate conflict monitoring and adjustments in control.

Conflict monitoring by the anterior cingulate cortex (ACC) has been posited to signal a need for greater cognitive control, producing neural and behavioral adjustments. However, the very occurrence of behavioral adjustments after conflict has been questioned, along with suggestions that there is no direct evidence of ACC conflict-related activity predicting subsequent neural or behavioral adjustments in control. Using the Stroop color-naming task and controlling for repetition effects, we demonstrate that ACC conflict-related activity predicts both greater prefrontal cortex activity and adjustments in behavior, supporting a role of ACC conflict monitoring in the engagement of cognitive control.

Adult↗

PubMed2003

The relationship between formal thought disorder and executive functioning component processes.

In 2 studies, associations between formal thought disorder (FTD) and 2 components of executive functioning, processing of context and interference resolution, were investigated. One study, involving people with schizophrenia, examined associations between performance on processing of context (N-back) and interference resolution (interference in Steinberg probe recognition) tasks and FTD. The second study, involving nonpsychiatric participants, was an analogue study that examined the effects of simulated processing of context (performance of 1-back with distraction) and interference resolution (telling new stories about previously seen pictures) deficits on FTD in a speech production task. In both studies, processing of context deficits predicted FTD. Moreover, in both studies, the effect of processing of context deficits on FTD was especially pronounced when combined with interference resolution deficits.

Adult↗

PubMed2003

Psychological trauma and schizotypal symptoms.

In a sample of 75 women recruited from the community, we measured trauma/maltreatment history and symptoms of schizotypal personality disorder, using both questionnaire and interview measures. As hypothesized, individuals with histories of trauma/maltreatment had elevated levels of schizotypal symptoms. Among types of trauma/maltreatment, reported childhood neglect was especially strongly associated with schizotypal symptoms. Although posttraumatic stress disorder symptom severity, depression, dissociation, and difficulty identifying one's emotions were all associated with schizotypal symptoms, they could not account completely for the association between trauma/maltreatment and schizotypal symptoms.

Adolescent↗

PubMed2002

Cognitive impairments associated with formal thought disorder in people with schizophrenia.

Formal thought disorder (FTD), or disorganized speech, is one of the central signs of schizophrenia. Despite extensive research, the cognitive processes associated with FTD are still unclear. However, the authors' review of FTD theories and research indicates that considerable progress has been made in identifying possible cognitive impairments associated with FTD. Specifically, FTD is strongly associated with impaired executive functioning and with impaired processing of semantic information. Their review indicates that previous research has not yet supported an association between FTD and either an increase in spreading activation or an impairment within the language production system.

Cognition Disorders↗