Kent A. Kiehl

Error processing and the rostral anterior cingulate: An event‐related fMRI study

The anterior cingulate is believed to play a crucial role in the regulation of thought and action. Recent evidence suggests that the anterior cingulate may play a role in the detection of inappropriate responses. We used event-related functional magnetic resonance imaging techniques to examine the neural responses to appropriate (correct rejects and correct hits) and inappropriate (errors of commission) behavioral responses during a go/no-go task. Analyses of the inappropriate responses revealed extensive activation in the rostral anterior cingulate cortex and in the left lateral frontal cortex. These areas were not activated for correctly classified trials (correct rejects and correct hits). These data suggest that the rostral anterior cingulate and left lateral frontal cortex are integral components of the brains error checking system.

Limbic abnormalities in affective processing by criminal psychopaths as revealed by functional magnetic resonance imaging

BACKGROUNDnPsychopathy is a complex personality disorder of unknown etiology. Central to the disorder are anomalies or difficulties in affective processing.nnnMETHODSnFunctional magnetic resonance imaging was used to elucidate the neurobiological correlates of these anomalies in criminal psychopaths during performance of an affective memory task.nnnRESULTSnCompared with criminal nonpsychopaths and noncriminal control participants, criminal psychopaths showed significantly less affect-related activity in the amygdala/hippocampal formation, parahippocampal gyrus, ventral striatum, and in the anterior and posterior cingulate gyri. Psychopathic criminals also showed evidence of overactivation in the bilateral fronto-temporal cortex for processing affective stimuli.nnnCONCLUSIONSnThese data suggest that the affective abnormalities so often observed in psychopathic offenders may be linked to deficient or weakened input from limbic structures.

Event-related fMRI study of response inhibition

Event‐related functional magnetic resonance imaging (erfMRI) was employed to measure the hemodynamic response during a Go/No‐go task in 16 healthy subjects. The task was designed so that Go and No‐go events were equally probable, allowing an unbiased comparison of cerebral activity during these two types of trials. In accordance with prediction, anterior cingulate was active during both the Go and No‐go trials, dorsolateral and ventrolateral prefrontal cortex was more active during the No‐go trials, while primary motor cortex, supplementary motor area, pre‐motor cortex and cerebellum were more active during Go trials. These findings are consistent with the hypothesis that the anterior cingulate cortex is principally engaged in making and monitoring of decisions, while dorsolateral and ventral lateral prefrontal sites play a specific role in response inhibition. Hum. Brain Mapping 12:100–109, 2001.

Neural sources involved in auditory target detection and novelty processing: an event-related fMRI study.

We used event-related functional magnetic resonance imaging (erfMRI) techniques to examine the cerebral sites involved with target detection and novelty processing of auditory stimuli. Consistent with the results from a recent erfMRI study in the visual modality, target processing was associated with activation bilaterally in the anterior superior temporal gyrus, inferior and middle frontal gyrus, inferior and superior parietal lobules, anterior and posterior cingulate, thalamus, caudate, and the amygdala/hippocampal complex. Analyses of the novel stimuli revealed activation bilaterally in the inferior frontal gyrus, insula, inferior parietal lobule, and in the inferior, middle, and superior temporal gyri. These data suggest that the scalp recorded event-related potentials (e.g., N2 and P3) elicited during similar tasks reflect an ensemble of neural generators located in spatially remote cortical areas.

An event-related potential investigation of response inhibition in schizophrenia and psychopathy

BACKGROUNDnSchizophrenia and psychopathy are both characterized by impulsive, poorly planned behavior. This behavior may originate from a weak or poorly coordinated response inhibition system. We tested the hypothesis that schizophrenia and psychopathy are associated with abnormal neural processing during the suppression of inappropriate responses.nnnMETHODSnThe participants were schizophrenic patients, nonpsychotic psychopaths, and nonpsychotic, nonpsychopathic control subjects (defined by the Hare Psychopathy Checklist-Revised), all incarcerated in a maximum security psychiatric facility. We recorded behavioral responses and event-related potentials (ERPs) during a Go/No Go task.nnnRESULTSnSchizophrenic patients made more errors of commission than did the nonpsychopathic offenders. As expected, the nonpsychopathic nonpsychotic participants showed greater frontal ERP negativity (N275) to the No Go stimuli than to the Go stimuli. This effect was small in the schizophrenic patients and absent in the psychopaths. For the nonpsychopaths, the P375 ERP component was larger on Go than on No Go trials, a difference that was absent in schizophrenic patients and in the opposite direction in psychopaths.nnnCONCLUSIONSnThese findings support the hypothesis that the neural processes involved in response inhibition are abnormal in both schizophrenia and psychopathy; however, the nature of these processes appears to be different in the two disorders.

Neural Pathways Involved in the Processing of Concrete and Abstract Words

The purpose of this study was to delineate the neural pathways involved in processing concrete and abstract words using functional magnetic resonance imaging (fMRI). Word and pseudoword stimuli were presented visually, one at a time, and the participant was required to make a lexical decision. Lexical decision epochs alternated with a resting baseline. In each lexical decision epoch, the stimuli were either concrete words and pseudowords, or abstract words and pseudowords. Behavioral data indicated that, as with previous research, concrete word stimuli were processed more efficiently than abstract word stimuli. Analysis of the fMRI data indicated that processing of word stimuli, compared to the baseline condition, was associated with neural activation in the bilateral fusiform gyrus, anterior cingulate, left middle temporal gyrus, right posterior superior temporal gyrus, and left and right inferior frontal gyrus. A direct comparison between the abstract and concrete stimuli epochs yielded a significant area of activation in the right anterior temporal cortex. The results are consistent with recent positron emission tomography work showing right hemisphere activation during processing of abstract representations of language. The results are interpreted as support for a right hemisphere neural pathway in the processing of abstract word representations. Hum. Brain Mapping 7:225–233, 1999.

An event-related functional magnetic resonance imaging study of an auditory oddball task in schizophrenia

Schizophrenia is a diffuse brain disease that affects many facets of cognitive function. One of the most replicated findings in the neurobiology of schizophrenia is that the event-related potentials to auditory oddball stimuli are abnormal, effects believed to be related to abnormalities in attentional and memory processes. Although event-related potentials provide excellent resolution regarding the time course of information processing, such studies are poor at characterizing the spatial location of these abnormalities. To address this issue, we used event-related functional magnetic resonance imaging techniques to elucidate the neural areas underlying target detection in schizophrenia. Consistent with recent event-related functional magnetic resonance imaging results, target processing by control participants was associated with bilateral activation in the anterior superior temporal gyri, inferior and superior parietal lobules, and activation in anterior and posterior cingulate, thalamus, and right lateral frontal cortex. For the schizophrenic patients, selective deficits were observed in both the extent and strength of activation associated with target processing in the right lateral frontal cortex, thalamus, bilateral anterior superior temporal gyrus, anterior and posterior cingulate, and right inferior and superior parietal lobules. These findings are consistent with the evidence for abnormal processing of oddball stimuli suggested by event-related potential studies in schizophrenic patients, but provide much more detailed evidence regarding the anatomical sites implicated. These data are consistent with the hypothesis that schizophrenia is characterized by a widespread pathological process affecting many cerebral areas, including association cortex and thalamus.

Detection of Sounds in the Auditory Stream: Event-Related fMRI Evidence for Differential Activation to Speech and Nonspeech

The detection of speech in an auditory stream is a requisite first step in processing spoken language. In this study, we used event-related fMRI to investigate the neural substrates mediating detection of speech compared with that of nonspeech auditory stimuli. Unlike previous studies addressing this issue, we contrasted speech with nonspeech analogues that were matched along key temporal and spectral dimensions. In an oddball detection task, listeners heard nonsense speech sounds, matched sine wave analogues (complex nonspeech), or single tones (simple nonspeech). Speech stimuli elicited significantly greater activation than both complex and simple nonspeech stimuli in classic receptive language areas, namely the middle temporal gyri bilaterally and in a locus lateralized to the left posterior superior temporal gyrus. In addition, speech activated a small cluster of the right inferior frontal gyrus. The activation of these areas in a simple detection task, which requires neither identification nor linguistic analysis, suggests they play a fundamental role in speech processing.

Removal of confounding effects of global signal in functional MRI analyses.

Local signals obtained from BOLD fMRI are generally confounded by global effects. In this paper, we make an essential distinction between global effects and the global signal. Global effects have a similar influence on local signals from a large proportion of cerebral voxels. They may reflect diffuse physiological processes or variations in scanner sensitivity and are difficult to measure directly. Global effects are often estimated from the global signal, which is the spatial average of local signals from all cerebral voxels. If the global signal is strongly correlated with experimental manipulations, meaningfully different results may be obtained whether or not global effects are modeled (G. K. Aguirre et al., 1998, NeuroImage, 8, 302-306). In particular, if local BOLD signals make a significant contribution to the global signal, analyses using ANCOVAor proportional scaling models may yield artifactual deactivations. In this paper, we present a modification to the proportional scaling model that accounts for the contribution of local BOLD signals to the global signal. An event-related oddball stimulus paradigm and a block design working memory task were used to illustrate the efficacy of our model.

Semantic and affective processing in psychopaths: An event-related potential (ERP) study

We tested the hypothesis that psychopathy is associated with abnormal processing of semantic and affective verbal information. In Task 1, a lexical decision task, and in Task 2, a word identification task, participants responded faster to concrete than to abstract words. In Task 2, psychopaths made more errors identifying abstract words than concrete words. In Task 3, a word identification task, participants responded faster to positive than to negative words. In all three tasks, nonpsychopaths showed the expected event-related potential (ERP) differentiation between word stimuli, whereas psychopaths did not. In each task, the ERPs of the psychopaths included a large centrofrontal negative-going wave (N350); this wave was absent or very small in the nonpsychopaths. The interpretation and significance of these differences are discussed.