The roles of orbital frontal cortex in the modulation of antisocial behavior

This article considers potential roles of orbital frontal cortex in the modulation of antisocial behavior. Two forms of aggression are distinguished: reactive aggression elicited in response to frustration/threat and goal directed, instrumental aggression. It is suggested that orbital frontal cortex is directly involved in the modulation of reactive aggression. It is argued that orbital frontal cortex does not "inhibit" reactive aggression but rather may both increase or decrease its probability as a function of social cues present in the environment. Early dysfunction in this function of orbital frontal cortex may be linked to the development of Borderline Personality Disorder. Instrumental aggression is linked to a fundamental failure in moral socialization. However, the available data suggest that the amygdala, but not orbital frontal cortex, is required for functions such as aversive conditioning and passive avoidance learning that are necessary for moral socialization. Psychopathic individuals who present with significant instrumental aggression, are impaired in aversive conditioning and passive avoidance learning and show evidence of amygdala dysfunction. Orbital frontal cortex and the amygdala are involved in response reversal where instrumental responses must be reversed following contingency change. Impairments in response reversal are also seen in psychopathic individuals. However, it remains unclear whether impairment in response reversal per se is associated with antisocial behavior.     

Integrating rewards and cognition in the frontal cortex

Research indicates that the dorsolateral prefrontal cortex (DLPFC) contributes to working memory and executive control, whereas the ventral frontal cortex (VFC) contributes to affective and motivational processing. Few studies have examined both the functional specificity and the integration of these regions. We did so using fMRI and a verbal working memory task in which visual cues indicated whether recall performance on an upcoming trial would be linked to a monetary reward. On the basis of prior findings obtained in delayed response tasks performed by nonhuman primates, we hypothesized that (1) VFC would show an increase only in response to a cue indicating potential for a monetary reward; (2) DLPFC would show sustained activity across a delay interval for all trials, though activity in rewarded trials would be enhanced; and (3) regions engaged in speech-based rehearsal would be relatively insensitive to monetary incentive. Our hypotheses about DLPFC and rehearsal-related regions were confirmed. In VFC regions, we failed to observe statistically significant effects of reward when the cue or delay epochs of the task were examined in isolation. However, an unexpected and significant deactivation was observed in VFC during the delay epoch; furthermore, a post hoc voxelwise analysis indicated a complex interaction between (1) the cue and delay epochs of the task and (2) the reward value of the trials. The pattern of activation and deactivation across trial types suggests that VFC is sensitive to reward cues, and that portions of DLPFC and VFC may work in opposition during the delay epoch of a working memory task in order to facilitate task performance.     

Left orbital frontal activation in pathological anxiety

Twelve patients with anxiety disorder were studied with respect to regional cerebral blood flow (rCBF) using a 32-detector system with the 133 Xe inhalation technique. Measurements were taken during a rest condition and during anxiety induction. Anxiety relevant to the patient's psychological disorder was induced with a projective test, the meta-contrast technique (MCT). Increased blood flow in the orbital frontal region of the left hemisphere was observed in each of the 11 subjects who showed evidence of experiencing anxiety during the procedure. In a second study four additional anxiety patients were studied with a high-resolution (254-detector)Xe rCBF system. In addition to the anxiety and resting conditions, a neutral verbalization condition was added to control for the verbal aspects of the anxiety induction procedure. The results again showed the experience of anxiety to be accompanied by increased blood flow in the left orbital frontal region, with the patients showing this flow increase to be greater in the posterior, paralimbic, areas of the region. These results are consistent with previous suggestions of left hemisphere involvement in anxiety. They also suggest that imaging methods may allow research into what appears to be exaggerated corticolimbic activity in this disorder.     

The functions of the orbitofrontal cortex

The orbitofrontal cortex contains the secondary taste cortex, in which the reward value of taste is represented. It also contains the secondary and tertiary olfactory cortical areas, in which information about the identity and also about the reward value of odours is represented. The orbitofrontal cortex also receives information about the sight of objects from the temporal lobe cortical visual areas, and neurons in it learn and reverse the visual stimulus to which they respond when the association of the visual stimulus with a primary reinforcing stimulus (such as taste) is reversed. This is an example of stimulus-reinforcement association learning, and is a type of stimulus-stimulus association learning. More generally, the stimulus might be a visual or olfactory stimulus, and the primary (unlearned) positive or negative reinforcer a taste or touch. A somatosensory input is revealed by neurons that respond to the texture of food in the mouth, including a population that responds to the mouth feel of fat. In complementary neuroimaging studies in humans, it is being found that areas of the orbitofrontal cortex are activated by pleasant touch, by painful touch, by taste, by smell, and by more abstract reinforcers such as winning or losing money. Damage to the orbitofrontal cortex can impair the learning and reversal of stimulus-reinforcement associations, and thus the correction of behavioural responses when there are no longer appropriate because previous reinforcement contingencies change. The information which reaches the orbitofrontal cortex for these functions includes information about faces, and damage to the orbitofrontal cortex can impair face (and voice) expression identification. This evidence thus shows that the orbitofrontal cortex is involved in decoding and representing some primary reinforcers such as taste and touch; in learning and reversing associations of visual and other stimuli to these primary reinforcers; and in controlling and correcting reward-related and punishment-related behavior, and thus in emotion. The approach described here is aimed at providing a fundamental understanding of how the orbitofrontal cortex actually functions, and thus in how it is involved in motivational behavior such as feeding and drinking, in emotional behavior, and in social behavior.     

Executive functions and the frontal lobes: a conceptual view

Several problems in understanding executive functions and their relationships to the frontal lobes are discussed. Data are then presented from several of our studies to support the following statements: (1) the examination of patients with focal frontal lobe lesions is a necessary first step in defining the relation of executive functions to the frontal lobes; (2) there is no unitary executive function. Rather, distinct processes related to the frontal lobes can be differentiated which converge on a general concept of control functions; (3) a simple control-automatic distinction is inadequate to explain the complexity of control-automatic processes; (4) the distinction between complex and simple tasks cannot explain the differences in functions between the frontal lobes and other brain regions; and (5) the most important role of the frontal lobes may be for affective responsiveness, social and personality development, and self-awareness and unconsciousness. Received: 31 March 1999 / Accepted: 23 July 1999     

Medial frontal cortex function: An introduction and overview

The growing attention being given to medial frontal cortex (MFC) in cognitive neuroscience studies has fostered a number of theoretical and paradigmatic perspectives that diverge in important ways. This has led to a great deal of research fractionation, with investigators studying domains and issues in MFC function that sometimes bear (at least at the surface) little relation to the questions addressed by others studying the same brain region. The present issue of Cognitive, Affective, & Behavioral Neuroscience presents articles inspired by a conference bringing together views from across this diversity of research, highlighting both the richness and vibrancy of the field and the challenges to be faced in terms of integration, synthesis, and precision among the theoretical accounts. The present article presents a brief introduction, overview, and road map to the field and to the special issue devoted to MFC function.     

Data on the role of the frontal cortex in vegetative behavior

A homeostatic conditional reflex (CR) was elaborated to the effect of repeated inhalations in rats of a gas mixture containing 8 per cent oxygen. The effect of the conditional response was opposite to that of the unconditional one. After ablation of the frontal cortex, the conditional reaction disappeared. The repeated administration of 40 mg/kg of histamine resulted in a tolerance to the temperature lowering effect of histamine similar to the habituation. An injection of distilled water brought about dishabituation. Tolerance was not influenced by the ablation of the frontal cortex, but the dishabituating effect of distilled water was absent.     

The representation of category typicality in the frontal cortex and its cross-linguistic variations

When asked to judge the membership of typical (e.g., car) vs. atypical (e.g., train) pictures of a category (e.g., vehicle), native English (N = 18) and native Chinese speakers (N = 18) showed distinctive patterns of brain activity despite showing similar behavioral responses. Moreover, these differences were mainly due to the amount and pervasiveness of category information linguistically embedded in the everyday names of the items in the respective languages, with important differences across languages in how pervasive category labels are embedded in item-level terms. Nonetheless, the left inferior frontal gyrus and the bilateral medial frontal gyrus are the most consistent neural correlates of category typicality that persist across languages and linguistic cues. These data together suggest that both cross- and within-language differences in the explicitness of category information have strong effects on the nature of categorization processes performed by the brain.     

Role of frontal cortex in attentional capture by singleton distractors

The role of frontal cortex in selective attention to visual distractors was examined in an attentional capture task in which participants searched for a unique shape in the presence or absence of an additional colour singleton distractor. The presence of the additional singleton was associated with slower behavioural responses to the shape target, and a greater neural signal in inferior frontal gyrus. To investigate the involvement of cognitive control functions of the frontal lobes in the capture of attention by the additional singletons, we measured the effect of the additional singleton in a context of either low or high working memory load. Whereas behavioural capture was unaffected by the level of load on working memory, greater activity associated with the presence of the additional singleton was observed in inferior frontal gyrus, but only under high load. This effect was greater in participants who experienced greater capture. We argue that the role of inferior frontal gyrus in selective attention is to detect potential sources of distraction.     

Memory and executive function impairments after frontal or posterior cortex lesions

Free recall and recognition, memory for temporal order, spatial memory and prospective memory were assessed in patients with frontal lobe lesions, patients with posterior cortex lesions and control subjects. Both patient groups showed equivalent memory deficits relative to control subjects on a range of free recall and recognition tasks, on memory for temporal order and on a prospective memory task. The patient groups also performed equivalently on the spatial memory task although only patients with frontal lobe lesions were significantly impaired. However, the patients with frontal lobe lesions showed an increased false alarm rate and made more intrusion errors relative not only to the control subjects, but also to the patients with poster or cortex lesions. These memory problems are discussed in relation to deficits in executive function and basic memory processes.     

Contrasting visuomotor functions of tectum and cortex in the golden hamster

Summary Visually-guided orientation (spatial localization) and visual discrimination were dissociated by means of brain lesions in the golden hamster. After ablation of visual cortex, hamsters failed to discriminate visual patterns, but showed nearly normal ability to localize an object in space by means of vision. Ablation of the superior colliculus produced opposite effects: these animals were completely unable to orient to the position of a visual stimulus, but nevertheless showed excellent pattern discrimination.

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Zusammenfassung Visuell gesteuerte Orientierung (räumliche Lokalisation) und visuelles Unterscheidungsvermögen beim Goldhamster werden durch Hirnläsionen funktionell getrennt. Nach Entfernung der Sehrinde können die Tiere keine visuellen Musterunterscheidungen, wohl aber noch in fast normaler Weise visuelle Objektlokalisationen vornehmen. Entfernung des Colliculus superior führt zu entgegengesetzten Effekten: die Tiere können sich nicht mehr nach der Position eines visuellen Reizes orientieren, zeigen aber trotzdem ausgezeichnete Musterunterscheidung.

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During the period of the reported research, the author was supported by a U.S. Public Health Service predoctoral fellowship. Additional support was received from the National Institute of General Medical Sciences under their Training Grant STl GM 1064-04 BHS.For a more detailed report of this work, and reports of further experiments, see Schneider (1966).     

Bootstrapping conceptual deduction using physical connection: rethinking frontal cortex

The age at which infants can demonstrate the ability to deduce abstract rules can be reduced by more than half, from 21 months to 9 months. The key is to introduce a physical connection between the items to be conceptually related. I argue here that making the same change in how items are presented might also help some preschoolers with learning delays, especially some children with autism. I also suggest that the roles of premotor and ventrolateral prefrontal cortices in deducing abstract rules might have been misinterpreted behaviorally and anatomically. The crucial brain region may be the periarcuate, which partially overlaps both premotor and lateral prefrontal cortex. The cognitive ability made possible by this region might be something far more elementary than previously considered: the ability to perceive conceptual connections in the absence of physical connection.     

Intra- and interindividual differences in lateralized cognitive performance and asymmetrical EEG activity in the frontal cortex

The study shows that changes in relative verbal vs. figural working memory and fluency performance from one session to a second session two to 3 weeks apart covary with spontaneously occurring changes of cortical asymmetry in the lateral frontal and central cortex, measured by electroencephalography (EEG) in resting conditions before the execution of tasks. That is, it was examined whether the current state of cortical asymmetry predicts verbal vs. figural performance. The findings complete the circle from studies showing correlations between changes of EEG asymmetry in the lateral frontal cortex and changes of mood to studies showing correlations between changes of mood and changes of relative verbal vs. figural working memory and fluency performance. The study suggests that state-dependent changes of lateralized cortical activity may underlie certain cognitive-emotional interactions observed in previous studies, and supports the assumption of reciprocal influences of specific emotional and specific cognitive processes.