Instrumental learning and relearning in individuals with psychopathy and in patients with lesions involving the amygdala or orbitofrontal cortex

Mitchell, D.G.V., Fine, C., Richell, R. A., Newman, C., Lumsden, J., Blair, K.S., & Blair, R. J. R. (2006). Instrumental learning and relearning in individuals with psychopathy and in patients with lesions involving the amygdala or orbitofrontal cortex. Neuropsychology 20(3), 280-289. doi: 10.1037/0894-4105.20.3.280

http://psycnet.apa.org/journals/neu/20/3/280.pdf

In Chapter 16 of the text, it discusses what happens when and how the brain does not act as it is supposed to normally function. While it includes the most common and most influential neurological and psychological disorders, such as epilepsy, traumatic brain injury, Parkinson’s, mood, and anxiety disorders, it neglects to mention personality disorders and their possible biological etiologies. One personality disorder I particularly find interesting is antisocial personality disorder, or psychopathy. The research article I found and many in the field of criminal justice use an assessment called Hare’s Psychopathy Checklist to describe and assess antisocial personality disorder. This checklist describes antisocial personality disorder with characteristics such as superficial charm, pathological lying, manipulative, shallow affect, callousness, and most markedly, a lack of remorse or guilt.

The researchers in this article wanted to functionally associate specific brain areas that may play a factor in psychopathy by comparisons to patients who had structural damage in these specific brain areas. The areas in question are the amygdala and the ventrolateral/orbitofrontal cortex (VL/OFC). Researchers chose these areas because there had previously been found to be learning deficits in individuals with psychopathy, and these certain types of learning had been found to use the amygdala and orbitofrontal cortex. More specifically, stimulus-reinforcement learning has been shown to use the amygdala and reversal learning has been shown to use the VL/OFC. As we have learned previously, the amygdala is used in classical conditioning, and psychopaths have shown slowed learning with classical conditioning. Also, the VL/OFC plays a key role in learning new associations, an area in which psychopaths have also shown to be slow at doing. In the first experiment, researchers had different groups complete a stimulus-reinforcement task to test their learning. The groups they wanted to compare were a patient with a left amygdala damage, two patients with acquired VL/OFC lesions, healthy control individuals, psychopathic inmates in a prison, and nonpsychopathic inmates. Researchers measured each participant’s level of psychopathy using Hare’s Psychopathy Checklist-Revised (PCL-R), and each participant completed a “Snake Game” used to assess instrumental learning and relearning. As expected, the participant with the damage to the left amygdala performed extremely worse than the normal control individuals during the initial learning of the correct responses. Similarly, individuals with psychopathy performed poorly on the initial instrumental learning, suggesting amygdala deficiencies in psychopaths. Also, as expected, the participants with lesions to the VL/OFC declined in performance, as re-learning was needed to keep track of the correct responses; this decline was not seen in the control individuals. In the two patients with VL/OFC damage, their initial stimulus-reinforcement learning was intact, but their reversal learning was impaired. The results of this study and previous studies suggest there is a neurological basis for psychopathy. Specifically, there seems to be a dysfunction in the amygdala, the VL/OFC, or both, that contribute to the development of psychopathy. Further supporting this, previous research has found that patients with amygdala damage and psychopaths show similar deficits in tasks and behaviors such as emotional memory tasks, fearful and vocal affect, and aversive conditioning. The same relationship is found between psychopaths and individuals with damage to the VL/OFC. For instance, extinction, reversal learning, and response to a real-life gambling task all suffer in both populations. To sum up, amygdala and VL/OFC dysfunction has been linked to psychopathy.