Evaluation of Frontal Ventral Contribution to the Psychopathy Syndrome in a Cognitive Neuropsychological Context
Dominique Lapierre (Department of Psychology, UQAM)
Issues and Research Objectives
The purposel of this research is to establish the involvement of specific regions of the brain, the prefrontal ventral regions (orbital and median), in psychopathy.
The prefrontal regions of the brain include the frontal ventral regions and the frontal dorsolateral cortex. These two regions of the prefrontal lobe are closely linked to several other structures in the brain: they receive afferents from them and emit efferents to them. For each of the regions, the connections to other regions are different, implying specialization and different roles for each. Thus, the frontal ventral regions would then play a specific role in the processing of olfactory information. These regions would also handle integration of sensory information with that coming from the organism’s internal environment. The frontal ventral regions are also connected to the frontal dorsolateral cortex, a link that would be the basis of mediation of internal processes by external perceptions, according to the motivational significance accorded to these.
In addition to the analysis of the anatomical links between the various regions, the study of the effects of lesions also provides information on the functioning of the prefrontal regions. When lesioned, the functioning of these regions is disturbed and there appear deficits such as: lack of spontaneity, pathological inertia, impulsiveness, disinhibition and alteration of the consciousness of the self. The functions of the prefrontal regions include direction of attention, discrimination of the importance of stimuli, formation of intent, development of a plan of action, execution of the action and analysis of the results obtained. More specifically, the ventral regions are above all responsible for the social and emotional adjustment of the individual, whereas the dorsolateral regions are more centered on regulation and integration of the cognitive functions. When prefrontal lesions occur during childhood, the symptoms seem to demonstrate interference in the development of introspection, social judgment, empathy, abstract reasoning and planning.
Studies on the effects of lesions have also been carried out in animals. These have demonstrated that a frontal ventral lesion in an animal is accompanied by maladjusted behavioral disinhibition, which gives rise to actions that are inadequately motivated and, in certain cases, acts that hinder achievement of the intended goal. With this type of lesion, difficulties in olfactory discrimination are also noted. Lesions elsewhere in the prefrontal lobe do not cause such olfactory difficulty. Studies on cats have provided evidence of the role of the ventral regions in the control of limbic mechanisms responsible for aggressiveness. Thus these lesions bring about aggressive behavior. In monkeys, ventral lesions give rise mostly to isolation, a loss of hierarchical status, fear of humans or fellow monkeys, and flight behavior. In one way or another, this type of lesion gives leads to an incapacity to modulate social responses. Finally, ventral lesions in animals are accompanied by changes at the autonomic level (heart rate, temperature, blood pressure, respiratory rate).
The study of ventral lesions in humans demonstrates that these cause attention deficits (high distractibility), perturbation of olfactory identification (anosmia), irritability, disinhibition of the sex drive, lack of consideration for moral and ethical principles, hyperactivity, impulsiveness, lack of judgment with regard to the consequences of behavior, lack of altruism, weak interpersonal relations and a tendency to commit antisocial and violent acts.
Dorsolateral lesions, on the other hand, present an entirely different picture, causing mostly difficulties in the mnesic processing of spatial information, in spatio-temporal integration of stimuli and in the motivational evaluation of a situation. These cases also demonstrate clinical symptoms such as apathy, a general lessening of activity, a significant loss of interest in one’s surroundings and a lack of spontaneity in reactions.
The clinical description of the psychopathic individual includes a set of antisocial behaviors and personality traits that contribute to serious relationship deficits. The psychopath often employs lies, coupled with a superficially charming attitude and smooth talk. Psychopaths overestimate their personal abilities and have no moral inhibitions. They have a strong tendency to manipulate others and demonstrate contempt, lack of involvement and a refusal of interpersonal ties. They are unable to feel deep emotions or affection. Their relationships are therefore established via sexual promiscuity and on a basis of affirming their personal power. Psychopaths are constantly searching for strong stimulation, and are therefore attracted by activities that involve risk. For psychopaths the mastery of their behavior is difficult: irritation can turn to verbally or physically aggressive behavior. They show intolerance to frustration, a lack of guilt, and an inability to plan coupled with a lack of concern for the future. Psychopaths often have a history of criminal activities, especially violent and aggressive crimes. Attempts at therapeutic intervention with psychopaths are generally futile.
Several studies have allowed the collection of psychophysiological and cognitive data specifically from psychopathic individuals. A difference in autonomic reaction was found with these individuals: they seem to have weaker than normal tonic electrodermal activity and they tolerate punitive consequences (shock) to an unusual degree. They nevertheless demonstrate a strong ability to focus their attention on a specific stimulus. At the language level, psychopaths demonstrate a deficit in understanding the affective sense of words in verbal situations. It would appear that psychopaths manifest anomalies related to left-hemisphere functions. The evaluation of frontal functions in these individuals sometimes produces a dysfunctional picture, and sometimes not. However, the studies that did investigate these functions did not all implement effective controls and only considered frontal functions from a global perspective.
The clinical profile of psychopaths is similar to that of individuals with a frontal lesion at the ventral level. In terms of sexuality, the actions of both these groups are similar: promiscuity and impersonal and ill-adjusted sexual acts. A relationship between the two groups has also been noted in terms of the lack of moral concern, the lack of altruism and the lack of judgment about the consequences of acts, despite normal cognitive functions. The two groups are also similar in their tendency toward aggressiveness, irritability, and violent action. The two types of patients also share a distinct profile in terms of vegetative functions. Finally, in both cases we find significant behavioral disinhibition. There are thus many similarities between the psychopath and the individual with ventrofrontal cerebral lesions, similarities that do not show up in individuals with cerebral lesions at the dorsolateral level.
In order to establish the link between psychopathy and dysfunction of the frontal ventral functions, a sample of two groups of subjects was recruited from the population of two medium-security penitentiaries (the Leclerc and Archambault facilities). The first group is composed of psychopathic criminals (n=30) and the second of non-psychopathic criminals (n=30). Subjects in both groups were equivalent in terms of age, sex, level of education, socio-economic status and the consumption of drugs, alcohol and cigarettes. Classification of subjects within the two groups was performed using the Hare Psychopathy Checklist.
Several tools were used to evaluate the subjects. Three instruments were used for the evaluation of frontal ventral functions: the Visual Discrimination Test (go/no-go) to measure the ability to resist interference from inappropriate stimuli, the Porteous Labyrinth Test to evaluate behavioral inhibition, and finally the Olfactory Discrimination Test to determine the ability of subjects to discriminate odors. Subjects were also subjected to a frontal dorsolateral test, the Wisconsin Card Sorting Test, to evaluate the integrity of dorsolateral functions, and to posterorolandic measures, the Mental Rotation Test and the Resemblance Test, to evaluate the integrity of anterior cortical functions. The research hypotheses anticipate that psychopathic criminal subjects will demonstrate lower performance than the control group on frontal ventral tests (more errors on the Visual Discrimination Test, a higher qualitative behavioral disinhibition score on the Labyrinth Test and a lower score on the Olfactory Discrimination Test) and equivalent performance on other tests.
The hypotheses formulated were all confirmed by the results. Thus, the psychopathic criminals achieved lower scores compared to the non-psychopathic criminals on the frontal ventral tests, and similar results in the other tests. These results are significant: several analyses on data normality, the parity between groups, the validity of measurements and the consumption of drugs during the evaluation, were performed to ensure the value of the data obtained, and variance analyses were also performed to verify the validity of the results.
The results demonstrating the existence of a specifically frontal ventral deficit in psychopaths and the absence of this deficit in non-psychopathic criminals were highly significant. The term deficit does not signify that there is a lesion or a massive dysfunction of the frontal ventral cortex in psychopaths. It would rather be the result of frontal orbital cortical and/or ventromedian under-activation, and other regions may also be implicated in the psychopathy syndrome, among others the circuit known as the frontal-septo-hippocampo, termed behavior inhibition system.
This research has certain limitations, specifically the significance of conclusions drawn by the instruments used, these having been applied to a population different from that on which they were standardized. A second limit deals with the choice of neuropsychological tests used: with three ventral measurements to only one dorsolateral measurement, the disequilibrium might possibly limit the conclusions concerning a deficit differential between these two regions.
Several avenues for future research are suggested by the current research: replication of this study would be pertinent, taking into account the limits discussed previously. It will also be interesting to examine the connection between psychopathy and certain neuropsychological aspects that seem to be linked to it (disorders of attention, language or learning processes). Finally, it will be interesting to see whether the singular nature of psychopathy also applies to other problems characterized by behavioural inhibition, such as hyperactivity, character disorders and hysteria.
Summary by: Maryse Pesant
Translation by: Madeleine Smith