Psychopathy: Legal and neuroscientific aspects

There are many instances in which the Spanish criminal law, more or less explicitly, allows or s that the offender's personality and willingness to engage in new criminal behaviour is taken into account. Without being exhaustive, this is the case in the current Spanish Criminal Code of the aggravating circumstance of recidivism (art. 22.8a) and its qualified form (art. 66.5a), with “the danger posed by the offender” to complement the principal punishment in certain crimes with certain accessory penalties (arts. 48 and 57), with the possibility of attending to the “personal circumstances of the offender” in the final determination of the sentence (art. 66.7a), with reference to the “individualised prognosis and favourable social reintegration” and “the personality of the convicted offender” to make certain decisions concerning the access to the third prison grade (art. 36) or probation (art. 90 and 92); and also the obligation for the judge or court to attend to the need for the execution of the sentence “to avoid the future commission of new crimes by the convicted person” as limit of the suspension of the execution of imprisonment (art. 80).

The increasing importance attached to the prediction of future behaviour in relation to the duration and specific circumstances of the execution of the sentence can lead to well-founded fears about the possible consequences of labelling the offender as a psychopath, because, after all, psychopathy is probably one of the offender's characteristics most negatively appraised by the legal system, constituting in practice an “aggravating circumstance” of criminal responsibility ( Fox, Kvaran, & Fontaine, 2013 ). Such severity in the criminal treatment of those who once labelled psychopaths supposedly represent a greater danger to society is often reflected in tougher penalties, not necessarily only in terms of their duration, but also in the intensity of their execution.

Paradoxically, the strict criminal treatment of individuals with psychopathy or other severe personality disorders does not recede when they are declared totally or partially not responsible. In these cases, the concurrence of a prognosis of recidivism (criminal dangerousness) does not simply result in the exemption or reduction of a sentence, which would be expected in other circumstances, but in the imposition of security measures that can also lead to the deprivation of freedom for a period of time that could reach the same duration of imprisonment had the subject been fully responsible; individuals may be confined to hospital settings, rather than to prison (interment in a psychiatric institution, arts. 6, 95 et seq. and 101 et seq. Penal Code, hereinafter: PC).

In theory, the imposition of security measures does not pose problems concerning criminally responsible or partially-responsible subjects, because the system recognises the absence of any cognitive or volitional impairments that should be taken into account. It is however controversial to impose security measures (in addition to sentences) on subjects declared fully responsible. In the case in particular of subjects affected by psychopathy, if we acknowledge that there is no effective treatment available – as it is usually said, the imposition of a security measure in addition to a sentence is questionable, because it would have no other objective than the prevention of injury interests of third parties or society as a whole. It is significant that even in the Anglo-American legal system, generally very willing to justify incapacitation (subtype of “desert-based detention”, through the extension of the length of the sentence and the aggravation of recidivism), serious doubts are raised in terms of establishing a “disease-based detention”, because it would considered incompatible with the precepts of the traditional “involuntary civil commitments” and “insanity acquittals followed by commitments”, and only imaginable as an extension of “commitment for mentally abnormal sexually violent predators” established in the legislation of several American States ( Morse, 2013).

The expansion of security measures to imputable subjects constitutes an incontestable fact in Spanish law, and its most obvious example is the security measure of supervised release, introduced in 2010 (its scope was expanded in the reform of the criminal code in 2015). However, a sound resistance to such recent political-criminal tendency is observed in a broad range of specialists who have dealt with it. Among others, Maraver Gómez (2015) and Rodríguez Horcajo (2014) have expressed their opposition from different perspectives. The reason for this criticism is not only found in the unreliability of prognosis of dangerousness, but also in the contradiction that may involve qualifying the same subject as responsible and dangerous, given the normative definition of a responsible subject as “someone from whom the order expects and demands conformance to the law” ( Peñaranda Ramos, 2015).

Determining whether it is possible to treat a mental disorder and, if applicable, how this may be done in a technically feasible way is strictly a matter of scientific inquiry. Law has nothing to say about this matter. But it is necessary to clearly distinguish the legitimacy of such eventual treatment.

Given the characteristics of psychopathy, it has been traditionally believed that psychopaths are not susceptible to be subjected to an effective treatment that prevents their willingness to engage in socially harmful behaviours. Some studies have even suggested that applied treatment programs, following for example the method of therapeutic communities, could be counterproductive ( Schug & Fradella, 2015 ). However, recent reviews of studies on which such pessimistic views are based have shown the severe limitations exhibited by the evaluated treatment programs. Skeem, Polaschek, Patrick, and Lilienfeld (2011) note that the only study that seems to confirm that treatment may increase the rates of recidivism of psychopathic offenders refers to a therapeutic community developed in a Canadian prison forensic hospital of maximum security in the 1960s, under conditions that hindered its potential effectiveness and would be considered completely unacceptable today.

The consideration of principle recently exposed by Maibom (2014) results extremely interesting when considering the effectiveness, legitimacy, and legality of treatment. This author points out the particularly problematic nature, from all these perspectives, presented by treatments that, because of involving the modification of personality traits closely connected to each other and with the whole moral disposition of the individual (with its own Weltanschauung ), could only be legitimately and effectively implemented with the collaboration of the individual.

The possibility to admit or exclude the criminal responsibility of psychopaths does not depend solely on the data provided by modern research in neuroscience, but also on the understanding gathered in the field of Philosophy and Law – and particularly in Criminal Law – about the corresponding notion of responsibility and the particular precepts that support it. However, it should be noted that such understanding is changing, partly because of the influence of recent scientific research about mental processes on criminal-legal and philosophical studies.

The article 20.1a of the Spanish Penal Code regulates the cause of exemption from criminal accountability known as “defense of anomaly or psychic alteration”. In short, this cause excludes the responsibility of anyone who, at the time of the offense, “cannot comprehend the unlawful nature of the act, or act in line with that comprehension” because of “any mental anomaly or alteration”. This exonerating circumstance s, therefore, that the existence of a disorder and its impact on the offense it accredited. This normative solution is known as “mixed formula”, as opposed to the “biological formula”, for which it is sufficient to offer proof of the disorder, and to the “psychological formula”, for which it is sufficient to prove the reduced capacity at the time of the offense without specifying the cause ( Díaz-Maroto Villarejo, 1988; Jorge Barreiro, 2000 ).

Psychopathy can be easily comprised by the broad concept of “mental disorder” d in the normative. What is more uncertain, even within the scientific community itself, is whether the effects of this “anomaly” truly incapacitate the subject in question to “comprehend the unlawful nature of the act, or act in line with that comprehension”. This is an aspect leading to great debate both within the courts and among academics.

The position of the Spanish Supreme Court suffers from a certain degree of conceptual misunderstanding when terms such as “psychopathy”, “antisocial personality disorder”, “antisocial borderline personality”, and “borderline personality disorder” are indistinctly used to refer to psychopaths. This makes it difficult to appreciate a precise criterion in its performance.

However, with some notable exception, the Spanish Supreme Court maintains that psychopathy does not exempt individuals from their responsibility, especially if this is the only anomaly presented. The Sentence of Spanish Supreme Court (hereinafter, STS) 10-07-2008 is highly illustrative in this regard, when declaring that psychopaths are “able to understand the wrongfulness of certain behaviours and to conform to moral and social norms, acting in accordance with that understanding, and that it is not sufficient to an aggressive and violent nature as a personality trait to reduce responsibility”. However, in several sentences it has been admitted that the responsibility of psychopaths is, to a greater or lesser extent, somewhat reduced, particularly when the subject presents any other condition in addition to psychopathy (for example, the STS 18-01-2012).

This relative homogeneity seen in jurisprudence is not observed however in the literature. Important authors, like Morse (2008) or Roxin (2006) and, in Spain, Cancio Meliá (2013) or Martínez Garay (2005) , believe that those who suffer from psychopathy – at least in particularly severe cases – lack, in light of the latest scientific findings, the minimum necessary conditions for them to be attributed full criminal responsibility, or even rule out that psychopaths (or at least some of them) have the necessary degree of rationality to be held criminally responsible for their actions.

The basis of this point of view differs across authors. According to some, such investigations have revealed that psychopaths lack the necessary evaluative standards to assess and responsibly guide their behaviour ( Litton, 2008 ), or even sensitivity to take into account purely prudential reasons against a criminal course of action ( Finlay, 2011 ). Others claim that psychopaths are capable of knowing the facts, the social and legal rules, and instrumentally pursuing their own interests, but reject they can be guided by moral reasoning, which would be a necessary component to fairly attribute to them a sentence genuinely deserved because of their “[blindness] to moral concerns” ( Morse, 2008).

Similarly, based on a stratified three-level distinction of moral responsibility – “attributability”, “answerability”, and “accountability”, Shoemaker (2015) notes it is quite difficult to accept the responsibility of primary psychopaths in this third level and, although more hesitantly, also in the second, because of their lack of “emotional empathy”, that is, the ability to feel what others feel and emotionally commit to them on the basis of such feelings, and other skills merely instrumental in nature, respectively.

In the same vein, it has also been suggested that the significant differences observed between “psychopaths” and “normal individuals” are so extreme that it is expected that the former will be considered criminally not responsible in the future. This is because psychopaths lack the basic and elemental level of empathy to be defined as “normal” ( Cancio Meliá, 2013).

However, the idea expressed by this last author, that such exclusion or reduction of criminal responsibility would also be normatively acceptable because the cases to be processed would be few and well-defined, is incongruent with the dimensional character, gradual and not categorical, of psychopathy, at least according to the measurement methods used so far for its diagnosis. Moreover, something that does not seem to fit with this idea is the fact that psychopaths do not stray much from the image of a normal person in normal circumstances as to declare them not responsible. As noted by Pilsbury (2013) , the selfish rationality of psychopaths (me-now) is not incomprehensible to the whole society.

For these or similar reasons, the determined and committed stance of that first group of authors does not express the most widespread view at the moment in the field of legal philosophy and criminal law. Many argue, in fact, that those investigations do not that people suffering from psychopathy completely lack the skills d to have a sufficiently profound moral knowledge of their actions. Still, not a few authors warn that criminal legal responsibility does not necessarily depend on whether the subject is also specifically receptive to moral reasons ( Maibom, 2008; Talbert, 2008).

In any case, there is currently a strong consensus that the consideration of individuals suffering from certain psychological disorders, in particular psychopathy and antisocial personality disorder, as criminally responsible or not responsible (unimputable) of their actions, is just a normative matter, which must be ultimately decided using specific criminal-legal criteria, and not simply by including those individuals in psychological or psychiatric categories ( Feijoo Sánchez, 2011; Pérez Manzano, 2011 ), because “not everything that explains behaviour is reason enough for its excuse” ( Martínez Garay, 2005).

Advances in neuroscience are undoubtedly improving the available knowledge about the explanation of human behaviour, but the reasons to excuse or not a certain behaviour depend on what society is reasonably willing to assume, and not on the nature of things. However, there is also an increasingly widespread consensus, in which the authors just cited take part, that legal assessment is not immune to the results of scientific research concerning the etiology of such disorders, their effects on the several capacities involved in guiding the individual's behaviour according to the demands of the legal and social order, and the treatment possibilities that can be offered to those who may need them. A more precise knowledge about all these aspects will also have an impact on the limits of responsibility and implementation of criminal penalties. Therefore, a dialogue between the sciences that empirically study these disorders and the legal and philosophical doctrines regarding criminal responsibility is necessary. Contributing to such dialogue is precisely one of the main objectives of this article.

Neuropsychology, by studying subjects with damage in specific brain regions, can compare their behaviour and personality with the behaviour and personality of psychopaths and help to locate the approximate areas of brain dys associated with psychopathy. This can be done using a number of tasks that are sensitive to damage to the ofPFC and vmPFC, although they must be modified for them to be sensitive enough and used in conjunction with observations of everyday life ( Zald & Andreotti, 2010).

Damage to the orbital surface of the frontal lobes leads to a syndrome known as pseudopsychopathy ( Blumer & Benson, 1975 ). Pseudopsychopathic behaviours emerge following damage to the ofPFC or the tracks that go across this region.

One of the first case studies that related psychopathy-like behaviours with prefrontal cortex damage was described in 1888 by Leonore Welt ( Benton, 1991 ); this subject fell from a fourth floor and suffered a penetrating frontal fracture when he was 37 years old. After a speedy recovery, a complete change in character was observed: from being an honest, hardworking, nice, and skilful person at work, he became aggressive, malicious, and driven to play unpleasant pranks. This change lasted about a month and he then began to improve and behave as he had always been, aware of his behaviour and repenting of it. After his death, the autopsy showed the destruction of the gyrus rectus in both hemispheres, as well as in the medial ofPFC and right vmPFC. Welt also examined another eight cases of subjects that showed personality changes, and autopsies always revealed that the ofPFC was involved ( Benton, 1991).

The patient EVR (Eslinger & Damasio, 1985 ) received surgery due to a meningioma in the ofPFC. Following the surgery, the subject showed damage to the vmPFC and ofPFC of both hemispheres. After his recovery, EVR took risks in his economic investments and went bankrupt; he received complaints from his employees, who said he was very disorganized despite showing appropriate manners and temperament. He had family difficulties that led to his divorce. Neuropsychological tests showed that his intelligence and memory were normal. However, he took a long time to complete tasks of everyday life because he showed difficulties in decision-making. In the neuropsychological study, EVR had little difficulty with tests designed to detect frontal lobe dyss. It is worth noting ( Eslinger & Damasio, 1985 ) that this patient showed a very significant dissociation between normal performance in neuropsychological tests and abnormal behaviour in real life.

Bechara, Damasio, and Damasio (2000) have extensively studied patients with damage to the vmPFC. In decision-making tasks, subjects without brain damage to the vmPFC, or with damage in other areas, make a greater number of beneficial decisions, while subjects with brain damage to the vmPFC persist in making inadequate decisions.

In a study with subjects with damage inside and outside the PFC, Gläscher et al. (2012) showed that a decision-making test was the only one associated with lesions in the ventral areas of the left medial PFC, dorsal areas of the right anterior PFC, ACC, and frontal lobe.

Hornak et al. (2003) studied patients whose lesions in the PFC were categorized as orbital, medial, and dorsolateral. Using tests of vocal emotion and facial expressions as well as questionnaires assessing their emotional subjective experience in their daily lives since they had undergone surgery, the most significant alterations were associated with the ofPFC.

For Szczepanski and Knight (2014) , individuals with damage to the ofPFC deficits in inhibition that have occasionally been characterised as impulsivity even though they have been better characterised as risky behaviour ( Alcázar-Córcoles, Verdejo-García, Bouso-Saiz, & Ortega-Escobar, 2015 ). Deficits in inhibition represent one of the critical points concerning psychopathy and Criminal Law. As we have seen, the Spanish Penal Code recognizes a legal defense when the offender “cannot comprehend the unlawful nature of the act, or act in line with that comprehension”. However, not any deficit can lead to a reduction in punishment. It needs a certain intensity (and it is, again, a legal question).

It is noteworthy that it has been determined that deficits in the Iowa Gambling Task (IGT) were exclusive of patients with damage to the medial ofPFC and vmPFC, and to the frontal pole. These authors reviewed other studies examining patients with damage to the ofPFC who a normal performance in the IGT. Therefore, these authors conclude that this test may not be ideal to assess the behavioural deficits specifically associated with damage to the ofPFC.

There are also studies of adults who suffered brain damage in early childhood ( Anderson, Bechara, Damasio, Tranel, & Damasio, 1999 ). One patient had a bilateral injury at 15 months of age that affected the ventromedial and polar prefrontal areas. A second patient had undergone the resection of a tumour in the right frontal hemisphere at three months of age, which involved both the medial and dorsal right polar areas. These patients were studied by the authors at 20 and 23 years of age, respectively. In the neuropsychological tests, they were unable to give appropriate responses to social situations or reason when faced with social dilemmas. Patients were not familiar with social rules, unlike individuals who have suffered damage in the ofPFC as adults; they showed lack of empathy or remorse. They also showed immature moral reasoning and a more intense antisocial behaviour than those who had suffered damage as adults; these subjects showed a behaviour similar to that of adult primary psychopaths.

Eslinger, Flaherty-Craig, and Benton (2004) summarized 10 cases of early damage to the PFC. The authors suggest that there were differences between injuries to the dlPFC, mPFC, or orbito-polar PFC. The age of onset of the injury was also important. The cases that were most severely affected were those who had suffered damage to the frontal lobe region and/or ofPFC and inferior mPFC. The emotions of these individuals were superficial, unstable, and strongly influenced by immediate situations. As with psychopaths, these patients did not seem to be able to learn from experience.

Another study conducted with eight patients with early-onset injury, before age 17, in the vmPFC was carried out by Taber-Thomas et al. (2014) . According to the results, the subjects supported significantly more subjective judgments that were against moral rules or involved inflicting harm to others, and the probability of these last behaviours was greater the earlier during development the damage in such cortical region had occurred. These results could be mediated by distorted cognitive processes that promote action while neutralizing guilt, and thereby maintaining the aggressor's positive self-image ( Roncero, Andreu, & Peña, 2016 ). However, the subjective assessment that someone makes of his previous conduct should not, as such, be considered in the field of Criminal Law. In this area it is enough that the offender is able to understand the “law's meaning”. A confluence between the offender's moral values and the values of law is not necessary. Criminal Law is not that ambitious.

There are some studies with subjects that have suffered damage to the amygdala because of calcification, due to the Urbach-Wiese disease. These subjects do not learn fear conditioning ( Bechara et al., 1995).

In most cases, patients with bilateral lesions in the amygdala do not social deficits that are clearly apparent. One explanation that has been offered for this is that in many cases it is unknown when the damage occurred during development, and it is possible they may have learned to behave in social situations. These patients are able to display normal emotional facial expressions, although they are not always able to correctly interpret the facial expressions of others ( Phelps & LeDoux, 2005).

The patient S. M. is unable to recognize facial expressions of fear, although she is able to recognize the identity of a face ( Adolphs, Tranel, Damasio, & Damasio, 1994 ), and this is essentially because she is unable to spontaneously fix her gaze in the eyes of subjects expressing the facial emotions ( Adolphs et al., 2005 ). When asked to look at the eyes of an image expressing the emotion of fear, then her performance is comparable to that of normal subjects ( Adolphs et al., 2005 ). S. M. expresses highly emotional and traumatic vital experiences in a dispassionate manner; in addition, even though she showed interest in other people, her threshold for the pain of another person was described as “quite high” ( Tranel, Gullickson, Koch, & Adolphs, 2006 ). In a later study ( Feinstein, Adolphs, Damasio, & Tranel, 2011 ), S. M. was exposed to a series of emotion-inducing stimuli, primarily fear (snakes and live spiders, strolling through a haunted house, seeing horror films interspersed with others that were intended to induce disgust, sadness, anger, etc.). S. M. did not fear responses to the animals, the haunted house, or the horror movies.

The structural neuroimaging studies of the brains of psychopaths have shown decreases (?) and increases (?) in volume in the following brain structures: ? hippocampus, ? cingulate gyrus and frontal, superior, and middle frontal gyri, ? ofPFC, ? temporal lobe, ? basolateral, lateral, central, and cortical nuclei of the amygdala ( Boccardi, 2013 ) and nucleus accumbens of the basal ganglia ( Boccardi et al., 2013).

Some studies have found significant associations between the amygdala's volume and psychopathic characters ( Gregory et al., 2012 ), although there may be no difference in volume if some nuclei increase in volume and others decrease, as observed in several studies ( Boccardi et al., 2011; Gopal et al., 2013; Yang, Raine, Narr, Colletti, & Toga, 2009; Yoder, Porges, & Decety, 2015 ).

In terms of the differences in cortical structures between individuals with and without psychopathy, some studies report a reduction in the volume of gray matter (cerebral cortex) in the anterior mPFC and temporal pole ( Gregory et al., 2012). Boccardi et al. (2011) and Ermer, Cope, Nyalakanti, Calhoun, and Kiehl (2012) observed decreases in the volume of gray matter of the ofPFC in their samples of psychopaths. A decrease in the volume of the ofPFC was also observed in a study in which unsuccessful psychopaths (who could not avoid criminal behaviour) were compared with successful psychopaths and control subjects ( Yang, Raine, Colletti, Toga, & Narr, 2010 ); unsuccessful psychopaths had less volume in the ofPFC than the subjects in the other two groups. Other studies are reviewed in Umbach, Berryessa, and Raine (2015) .

The morphology of axon tracts connecting different brain regions has also been studied. Two studies ( Craig et al., 2009; Motzkin, Newman, Kiehl, & Koenigs, 2011 ) found a reduced integrity in a tract, the uncinate fasciculus (UF), connecting the temporal lobe, where the amygdala is located, with the ofPFC ( Thiebaut de Schotten, Dell’Acqua, Valabregue, & Catani, 2012 ). The reduction in the integrity of the UF was associated with the Facet 4 of Factor 2 (poor behavioural control, behavioural problems in childhood, juvenile offenses, etc.). A study by Sundram et al. (2012) also found a reduction in the volume of the UF and a negative correlation with the Factor 2 of psychopathy, that is, with antisocial behaviour. A study by Wolff et al. (2015) found a reduction in the volume of the right UF, but also found that this reduction was specifically related to the Facet 1 of Factor 1 (interpersonal characteristics of the psychopath -pathological lying, grandiose sense of self-worth, manipulation, superficial charm). Therefore, this reduction in the right UF observed in all studies to date could be a biological marker of a distinguishing feature of psychopathy, such as interpersonal features.

Another study (Sethi et al., 2015 ) specifically examined the association of another fascicle, the dorsal portion of the fasciculus cingulate, connecting the PCC with the mPFC, with emotional indifference (Facet 2 of Factor 1: lack of remorse or guilt, superficial affect, lack of empathy, lack of responsibility for action). It has been proposed that the mechanism behind alterations in these two fascicles in psychopaths is the lack of maturation of the white matter ( Sethi et al., 2015).

There have also been studies of white matter anomalies in adolescents with behavioural disorders ( Pape et al., 2015; Sarkar et al., 2013 ). These have a high risk of developing antisocial personality disorder and psychopathy. The study by Sarkar et al. (2013) examined the UF but, unlike that observed in adults, the structural integrity of the UF was greater than that of controls. The study by Pape et al. (2015) showed that the “grandiose-manipulative” and “callous-unemotional” characters from the Youth Psychopathic Traits Inventory correlate with a variable set of fascicles of white matter and not just with the UF. This study shows a positive relationship between the UF and the “grandiose-manipulative” character, but not with the “callous-unemotional” and “impulsive-irresponsible” characters.

As in structural MRI, we by examining data about the amygdala. Kiehl et al. (2001) conducted the first study showing dys of the amygdala, using a comparison task of emotional and non-emotional words in a sample of eight offender psychopaths, eight non-offender psychopaths, and eight non-criminal controls. The psychopaths showed a smaller difference between the al responses to the two types of words in the amygdala, hippocampal formation, parahippocampal gyrus, nucleus accumbens, ACC and PCC.

Research using fMRI has been conducted to evaluate changes in the amygdala associated with moral judgments, processing of facial expressions, emotional memory, processing of abstract and concrete words, and theory of mind ( Blair, 2013b ). For example, a greater reduction in the activity of the amygdala in a moral-emotional decision-making task was found as the level of psychopathy exhibited by the subjects increased ( Glenn, Raine, & Schug, 2009 ). In addition, the reduced amygdala activity in this study correlated with the four facets of psychopathy, and in terms of cortical regions the mPFC, PCC, and the angular gyrus showed less activity in psychopaths who obtained high scores on the interpersonal factor.

It has also been proposed that psychopaths have an attenuated emotional response to fear and anxiety in particular ( Lykken, 1957 ). This attenuated fear response explains the deficit in fear conditioning, in the physiological anticipation of unpleasant events and, therefore, in the lack of fear or anxiety related to unpleasant events such as witnessing a subject being brutally hurt. Studies examining the ality of the amygdala during fear conditioning have arrived at contradictory results, some have found deficiencies ( Birbaumer et al., 2005 ), while others have reported increased activity in the amygdala ( Schultz, Balderston, Baskin-Sommers, Larson, & Helmstetter, 2016 ). We attribute such inconsistencies to methodological aspects.

The responses of the amygdala to facial expressions of fear, anger, surprise, and neutral expression were also examined in a sample of non-imprisoned young adults (mean age 19.65 ± 1.30 years), using a face-matching task ( Carré, Hyde, Neumann, Viding, & Hariri, 2013 ). The authors observed low activity in the amygdala in response to fear and high reactivity to anger. The low reactivity to fear was associated with the interpersonal facet, that is, with what can be described as the discomfort of the person showing the expression; such low activity to signs of fear has been suggested to be the basis of instrumental aggression. In turn, the high reactivity to expressions of anger was associated with the facet of life style, and would be the basis of reactive aggression. In contrast, a study by Decety, Skelly, Yoder, and Kiehl (2014) found no differences in the amygdala between psychopaths and non-psychopaths in response to facial expressions displayed using video clips.

From a legal perspective, it is a very difficult issue. If it were proven that punishment works worse with psychopaths (in other words, that here the punishment does not deter as much as it should) the legitimation of their punishment would be scarcer in some punishment's theories (for example in the “theory of deterrence”). The only sources of legitimacy would be, in that cases, the social ones. And it supposes a serious legitimacy problem. Nevertheless, it does not happen with all criminal theories (there is, then, here another important theoretical and legal question).

In terms of the prefrontal cortex in normal nonclinical subjects, the control of aggressive impulses translates into greater activity in the ofPFC ( Pietrini, Guazzelli, Basso, Jaffe, & Grafman, 2000 ). Also, the activity of the ofPFC increases when facial expressions of anger growing in intensity are observed ( Blair, Morris, Frith, Perrett, & Dolan, 1999 ).

One of the first al studies of the prefrontal cortex of psychopathic subjects was performed by Raine et al. (1998) , using positron emission tomography. The murderers they called predators (corresponding to psychopaths) had an activity of the prefrontal cortex (the authors did not distinguish among regions) similar to that of control subjects, but they showed greater subcortical activity.

Yang and Raine (2009) conducted a meta-analysis to try to integrate cortical al findings in psychopathic, antisocial, and violent individuals. The regions that showed a reduction in al activity were the right ofPFC, the right ACC, and the left dlPFC.

Several studies have found a reduced activation of the vmPFC and the ofPFC when psychopaths observe emotional facial expressions in people being hurt ( Decety et al., 2014; Marsh et al., 2013 ).

Research has also been conducted to examine the empathic interest and moral sensitivity of psychopaths, and which brain regions are related to these behaviours ( Decety, Chen, Harenski, & Kiehl, 2015; Decety & Moriguchi, 2007 ). These studies have demonstrated from a behavioural point of view that psychopaths are able to distinguish between right and wrong actions, in addition to interpret the emotional consequences of such actions on other people. Interestingly, it has been found using fMRI that when they are asked to pay attention to a perpetrator doing something wrong, there is decreased activity in areas that are related to empathy and perspective taking (amygdala, insula, nucleus accumbens, and several regions from the PFC such as the dlPFC, vlPFC, mPFC). However, psychopaths exhibited increased activation in these same network areas when they had to infer the emotional state of a victim of a harmful action. Nonetheless, these studies are still very recent and there are contradictory results, even among studies carried out by the same research group.