Tracking the subprocesses of decision-based action in the human frontal lobes

Anterior cingulate morphology in people at genetic high-risk of schizophrenia

Background

Morphological abnormalities of the anterior cingulate (AC) occur in patients with schizophrenia and in symptomatic high-risk individuals, and may be predictive of subsequent psychosis. We investigated AC sulcal morphology in the Edinburgh High Risk Study cohort to see if such abnormalities are evident and predict psychosis in patients’ relatives. We also investigated the association of the cingulate sulcus (CS) and paracingulate sulcus (PCS) variants with intelligence quotient (IQ).

Patients and methods

We compared cingulate and paracingulate sulcal anatomy, using reliable standardised measurements, blind to group membership, in those at high genetic risk (n = 146), first episode patients (n = 34) and healthy controls (n = 36); and compared high-risk subjects who did (n = 17) or did not develop schizophrenia.

Results

Interruptions of the cingulate sulcus were more common in high-risk individuals and in those with schizophrenia, in both hemispheres, compared to controls. When separated by gender, these results were only present in males in the left hemisphere and only in females in the right hemisphere. A well-formed paracingulate sulcus was less common in high-risk participants and patients with schizophrenia, compared to controls; but this association was only present in males. These morphological variants of the paracingulate sulcus and the continuous cingulate sulcus were also associated with the higher IQ in male high-risk individuals.

Conclusions

An interrupted cingulate sulcus pattern in both males and females and paracingulate morphology in males are associated with increased genetic risk of schizophrenia. Associations between cingulate and paracingulate morphology and premorbid IQ scores provide evidence that intellectual ability could be related to particular cytoarchitectural brain regions. Given that these sulci develop in early fetal life, such findings presumably reflect early neurodevelopmental abnormalities of genetic origin, although environmental effects and interactions cannot be ruled out.

Body mass correlates inversely with inhibitory control in response to food among adolescent girls: an fMRI study

Self-report and behavioral data suggest that impulsivity may contribute to the development and maintenance of obesity. Neuroimaging studies implicate a widespread neural network in inhibitory control and suggest that impulsive individuals show hypoactivity in these regions during tasks requiring response inhibition. Yet, research has not directly tested whether body mass correlates inversely with activation of these regions during response inhibition tasks. The present study used functional magnetic resonance imaging (fMRI) to investigate neural activations during a food-specific go/no-go task in adolescent girls ranging from lean to obese. When required to inhibit prepotent responses to appetizing food, body mass index (BMI) correlated with response inhibition at both the behavioral and neural levels, with more overweight adolescents showing greater behavioral evidence of impulsivity as well as reduced activation of frontal inhibitory regions, including superior frontal gyrus, middle frontal gyrus, ventrolateral prefrontal cortex, medial prefrontal cortex, and orbitofrontal cortex, than leaner individuals. As well, activation in food reward regions (e.g., temporal operculum/insula) in response to food images correlated positively with BMI. Results suggest that hypofunctioning of inhibitory control regions and increased response of food reward regions are related to elevated weight.

Detection of deception using fMRI: better than chance, but well below perfection

Functional brain imaging has been considered a new and better technique for the detection of deception. The reasoning is that there is a neural locus or circuit for lying that is sensitive, specific, generalizable across individuals and measurement contexts, and robust to countermeasures. To determine the extent to which the group results predicted lying at the level of the individual, we reanalyzed data on 14 participants from a study that had previously identified regions involved in lying (thus satisfying the criterion for sensitivity). We assessed the efficacy of functionally determined brain regions based on the lie-truth contrast for N-1 participants to detect deception in the Nth individual. Results showed that no region could be used to correctly detect deception across all individuals. The best results were obtained for medial prefrontal cortex (mPFC), correctly identifying 71% of participants as lying with no false alarms. Lowering the threshold for a response increased hits and false alarms. The results suggest that although brain imaging is a more direct index of cognition than the traditional polygraph, it is subject to many of the same caveats and thus neuroimaging does not appear to reveal processes that are necessarily unique to deception.

The neural correlates of third-party punishment

Legal decision-making in criminal contexts includes two essential functions performed by impartial "third parties:" assessing responsibility and determining an appropriate punishment. To explore the neural underpinnings of these processes, we scanned subjects with fMRI while they determined the appropriate punishment for crimes that varied in perpetrator responsibility and crime severity. Activity within regions linked to affective processing (amygdala, medial prefrontal and posterior cingulate cortex) predicted punishment magnitude for a range of criminal scenarios. By contrast, activity in right dorsolateral prefrontal cortex distinguished between scenarios on the basis of criminal responsibility, suggesting that it plays a key role in third-party punishment. The same prefrontal region has previously been shown to be involved in punishing unfair economic behavior in two-party interactions, raising the possibility that the cognitive processes supporting third-party legal decision-making and second-party economic norm enforcement may be supported by a common neural mechanism in human prefrontal cortex.

Neural correlates of post-error slowing during a stop signal task: a functional magnetic resonance imaging study

The ability to detect errors and adjust behavior accordingly is essential for maneuvering in an uncertain environment. Errors are particularly prone to occur when multiple, conflicting responses are registered in a situation that requires flexible behavioral outputs; for instance, when a go signal requires a response and a stop signal requires inhibition of the response during a stop signal task (SST). Previous studies employing the SST have provided ample evidence indicating the importance of the medial cortical brain regions in conflict/error processing. Other studies have also related these regional activations to postconflict/error behavioral adjustment. However, very few studies have directly explored the neural correlates of postconflict/error behavioral adjustment. Here we employed an SST to elicit errors in approximately half of the stop trials despite constant behavioral adjustment of the observers. Using functional magnetic resonance imaging, we showed that prefrontal loci including the ventrolateral prefrontal cortex are involved in post-error slowing in reaction time. These results delineate the neural circuitry specifically involved in error-associated behavioral modifications.

Somato-motor inhibitory processing in humans: an event-related functional MRI study

Inhibiting inappropriate behavior and thoughts is an essential ability for humans, but the regions responsible for inhibitory processing are a matter of continuous debate. This is the first study of somatosensory go/nogo tasks using event-related functional magnetic resonance imaging (fMRI). Fifteen subjects preformed two different types of go/nogo task, i.e. (1) Movement and (2) Count, to compare with previous studies using visual go/nogo tasks, and confirm whether the inhibitory processing is dependent on sensory modalities. Go and nogo stimuli were presented with an even probability. Our data indicated that the response inhibition network involved the dorsolateral (DLPFC) and ventrolateral (VLPFC) prefrontal cortices, pre-supplementary motor area (pre-SMA), anterior cingulate cortex (ACC), inferior parietal lobule (IPL), insula, and temporoparietal junction (TPJ), which were consistent with previous results obtained using visual go/nogo tasks. These activities existed in both Movement and Count Nogo trials. Therefore, our results suggest that the network for inhibitory processing is not dependent on sensory modalities but reflects common neural activities. In addition, there were differences of activation intensity between Movement and Count Nogo trials in the prefrontal cortex, temporal lobe, and ACC. Thus, inhibitory processing would involve two neural networks, common and uncommon regions, depending on the required response mode.

The influence of rTMS over the right dorsolateral prefrontal cortex on top-down attentional processes

Repetitive Transcranial Magnetic Stimulation (rTMS) provides a unique opportunity to study causal relationships between activity in the dorsolateral prefrontal cortex (DLPFC) and executive functioning, by modulating brain activity in SHAM controlled designs. We devised a new Stroop task paradigm in which subjects must engage in both strategic and automatic attentional processes. In the current experiment, we manipulated subjects' expectancies for incongruent stimuli. Previous research demonstrated that when subjects have a high level of expectancy that a stimulus will be incongruent, they are able to strategically adjust the relative influence of word reading on color naming. The effect of high frequency (HF) rTMS on Stroop performance of 20 right-handed healthy female volunteers was tested using a double blind within subjects design by counterbalanced crossover sham (placebo) and active rTMS over the right DLPFC. Since mood remained unchanged after rTMS, the Stroop data could be evaluated independent of mood changes. Only in the high expectancy condition, we found a decreased response time to both congruent and incongruent trials on the Stroop task performance after HF rTMS. The SHAM placebo condition yielded no effects. We conclude that high frequency stimulation over the right DLPFC has an effect on top-down attentional processes by modulating the attentional set.

The neural correlates of cross-modal interaction in speech perception during a semantic decision task on sentences: A PET study

Speech perception in face-to-face conversation involves processing of speech sounds (auditory) and speech-associated mouth/lip movements (visual) from a speaker. Using PET where no scanner noise was present, brain regions involved in speech cue processing were investigated with the normal hearing subjects with no previous lip-reading training (N = 17) carrying out a semantic plausibility decision on spoken sentences delivered in a movie file. Multimodality was ensured at the sensory level in all four conditions. Sensory-specific speech cue of one sensory modality, i.e., auditory speech (A condition) or mouth movement (V condition), was delivered with a control stimulus of the other modality whereas speech cues of both sensory modalities (AV condition) were delivered during bimodal condition. In comparison to the control condition, extensive activations in the superior temporal regions were observed bilaterally during the A condition but these activations were reduced in extent and left lateralized during the AV condition. Polymodal region such as left posterior superior temporal sulcus (pSTS) involved in cross-modal interaction/integration of audiovisual speech was found to be activated during the A and more so during the AV conditions but not during the V condition. Activations were observed in Broca's (BA 44), medial frontal (BA 8), and anterior ventrolateral prefrontal (BA 47) regions in the left during the V condition, where lip-reading performance was less successful. Results indicated that the speech-associated lip movements (visual speech cue) rendered suppression on the activity in the right auditory temporal regions. Overadditivity (AV > A + V) observed in the right postcentral region during the bimodal condition relative to the sum of unimodal speech conditions was also associated with reduced activity during the V condition. These findings suggested that visual speech cue could exert an inhibitory modulatory effect on the brain activities in the right hemisphere during the cross-modal interaction of audiovisual speech perception.

Empathizing: neurocognitive developmental mechanisms and individual differences

This chapter reviews the Mindreading System model encompassing four neurocognitive mechanisms (ID, EDD, SAM, and ToMM) before reviewing the revised empathizing model encompassing two new neurocognitive mechanisms (TED and TESS). It is argued that the empathizing model is more comprehensive because it entails perception, interpretation, and affective responses to other agents. Sex differences in empathy (female advantage) are then reviewed, as a clear example of individual differences in empathy. This leads into an illustration of individual differences using the Empathy Quotient (EQ). Finally, the neuroimaging literature in relation to each of the neurocognitive mechanisms is briefly summarized and a new study is described that tests if different brain regions respond to the perception of different facial expressions of emotion, as a function of the observer's EQ.