Electrophysiological analysis of the sleep onset period : a comparison between subjects with long term insomnia complaints associated with mild traumatic brain injury and matched controls /

The purpose of the current undertaking was to study the electrophysiological properties of the sleep onset period (SOP) in order to gain understanding into the persistent sleep difficulties of those who complain of insomnia following mild traumatic brain injury (MTBI). While many believe that symptoms of post concussion syndrome (PCS) following MTBI resolve within 6 to 12 months, there are a number of people who complain of persistent sleep difficulty. Two models were proposed which hypothesize alternate electrophysiological presentations of the insomnia complaints of those sustaining a MTBI: 1) Analyses of standard polysomnography (PSG) sleep parameters were conducted in order to determine if the sleep difficulties of the MTBI population were similar to that of idiopathic insomniacs (i.e. greater proportion ofREM sleep, reduced delta sleep); 2) Power spectral analysis was conducted over the SOP to determine if the sleep onset signature of those with MTBI would be similar to psychophysiological insomniacs (characterized by increased cortical arousal). Finally, exploratory analyses examined whether the sleep difficulties associated with MTBI could be explained by increases in variability of the power spectral data. Data were collected from 9 individuals who had sustained a MTBI 6 months to 5 years earlier and reported sleep difficulties that had arisen within the month subsequent to injury and persisted to the present. The control group consisted of 9 individuals who had experienced neither sleep difficulties, nor MTBI. Previous to spending 3 consecutive uninterrupted nights in the sleep lab, subjects completed questionnaires regarding sleep difficulties, adaptive functioning, and personality.

Psychopathy and Aggression: Examining the Role of Empathy

Empirical research has consistently demonstrated a positive association between psychopathic traits and physical aggression (Campbell, Porter, & Santor, 2004; Gretton, Hare, & Catchpole, 2004; Raine et aI., 2006; Spain, Douglas, Poythress, & Epstein, 2004). Moreover, research has also found that the emotional/interpersonal (Factor 1) psychopathy traits tend to be more closely associated with goal oriented, proactive aggression, whereas the social deviance (Factor 2) psychopathy characteristics have been more closely linked to reactive aggression, which is perpetrated in response to threat or provocation (Flight & Forth, 2007). Blair (2004; 2005; 2006) has recently proposed the Integrated Emotions Systems Model (lES), which posits that the association between Factor 1 psychopathy traits and proactive aggression is due to amygdala dysfunction leading to failed moral socialization. Consequently, individuals who exhibit Factor 1 psychopathy traits do not experience affective empathy in response to distress cues exhibited by others, thus, preventing the inhibition of proactive aggression. The current investigation sought to test this model by examining the associations among the emotional/interpersonal (Factor 1) psychopathy traits, proactive aggression, and affective empathy. After accounting for head injury, Factor 2 psychopathy traits, reactive aggression, and cognitive empathy, it was hypothesized that 1) Factor 1 psychopathy traits would predict proactive aggression, and 2) that affective empathy is a common cause of Factor 1 psychopathy traits, proactive aggression, and of the relationship between these two constructs. This hypothesis assumed that (a) affective empathy would uniquely predict Factor 1 psychopathy traits, (b) that affective empathy would uniquely predict proactive aggression, and (c) that affective empathy would account for the relationship between Factor I psychopathy traits and proactive aggression. The total sample consisted of 137 male undergraduate students. Participants completed measures of psychopathy (SRP III; Paulhus, Hemphill, & Hare, in press), aggression (PCS; Marsee, Kimonis, & Frick, 2004; RPQ; Raine et at, 2006), dispositional cognitive and affective empathy (BES; Jolliffe & Farrington, 2006; TES; Spreng, McKinnon, Mar, & Levine, 2009), and situational cognitive and affective empathy in response to neutral and empathy eliciting video clips. Physiological indices (heart rate & electrodermal activity) of affective empathy were also obtained while participants viewed the neutral and empathy eliciting videos. Findings indicated that Factor I psychopathy traits predicted proactive aggression. In addition, results demonstrated that affective empathy predicted both Factor I psychopathy traits and proactive aggression. However, the association between affective empathy and proactive aggression appeared to be dependent on the conceptualization and measurement of affective empathy. Conversely, affective empathy did not appear to account for the relationship between Factor I psychopathy traits and proactive aggression. Overall, results demonstrated partial support for the IES model. Implications of the results, limitations of the study and future research directions are discussed.