The connections of prefrontal cortex (PFC) were investigated in the rat brain to determine the order and location of input and output connections to motor and somatosensory cortex. Retrograde (100nl Fluoro-Gold) and anterograde (100nl Biotinylated Dextran Amines; Fluorescein and Texas Red) neuronanatomical tracers were injected into the subdivisions of the prefrontal cortex (prelimbic, ventral orbital, ventrolateral orbital, dorsolateral orbital) and their projections studied. We found clear evidence for organised input projections from the motor and somatosensory cortices to the prefrontal cortex, with distinct areas of motor and cingulate cortex projecting in an ordered arrangement to the subdivisions of prefrontal cortex. As injection location of retrograde tracer was moved from medial to lateral in PFC, we observed an ordered arrangement of projections occurring in sensory-motor cortex. There was a significant effect of retrograde injection location on the position of labelled cells occurring in sensory-motor cortex (dorsoventral, anterior-posterior and mediolateral axes p<.001). The arrangement of output projections from prefrontal cortex also displayed a significant ordered projection to sensory-motor cortex (dorsoventral p<.001, anterior-posterior p=.002 and mediolateral axes p<.001). Statistical analysis also showed that the locations of input and output labels vary with respect to one another (in the dorsal-ventral and medial-lateral axes, p<.001). Taken together, the findings show that regions of prefrontal cortex display an ordered arrangement of connections with sensory-motor cortex, with clear laminar organisation of input connections. These results also show that input and output connections to prefrontal cortex are not located in exactly the same sites and reveal a circuit between sensory-motor and prefrontal cortex.

Understanding the structural organisation of the prefrontal cortex (PFC) is an important step towards determining its functional organisation. Here we investigated the organisation of PFC using different neuronal tracers. We injected retrograde (Fluoro-Gold, 100nl) and anterograde (Biotinylated dextran amine (BDA) or Fluoro-Ruby, 100nl) tracers into sites within PFC subdivisions (prelimbic, ventral orbital, ventrolateral orbital, dorsolateral orbital) along a coronal axis within PFC. At each injection site one injection was made of the anterograde tracer and one injection was made of the retrograde tracer. The projection locations of retrogradely labelled neurons and anterogradely labelled axon terminals were then analysed in the temporal cortex: area Te, entorhinal and perirhinal cortex. We found evidence for an ordering of both the anterograde (anterior-posterior, dorsal-ventral and medial-lateral axes: p<0.001) and retrograde (anterior-posterior, dorsal-ventral and medial-lateral axes: p<0.001) connections of PFC. We observed that anterograde and retrograde labelling in ipsilateral temporal cortex (i.e. PFC inputs and outputs) often occurred reciprocally (i.e. the same brain region, such as area 35d in perirhinal cortex, contained anterograde and retrograde labelling). However, often the same specific columnar temporal cortex regions contained only either labelling of retrograde or anterograde tracer, indicating that PFC inputs and outputs are frequently non-matched.

Childhood trauma is linked to impairments in executive function and working memory, thought to underly psychological disorders including depression and posttraumatic stress disorder. Research demonstrates that childhood trauma can partially mediate posttraumatic stress disorder in those with executive function deficits. Despite a link with executive function deficit, psychopathy as a consequence of trauma is yet to be studied in this context. The present study investigates the possibility of a relationship between childhood trauma, psychopathic traits, and response inhibition. Eighty participants were tasked to completed the Childhood Traumatic Events Scale (Pennebaker & Susman, 2013), Levenson’s Self-Report Psychopathy Scale (Levenson et al., 1995), and Flanker task of response inhibition (Eriksen & Eriksen, 1974). Scores of trauma exposure, psychopathic traits, and reaction times in the Flanker task were measured. Regression analysis revealed no significance for trauma exposure in predicting psychopathic traits (p = .201) and response inhibition (p = .183), indicating that childhood trauma does not strongly predict susceptibility to psychopathic traits or response inhibition deficits. These findings form an important basis on which to build a further understanding of the consequences of childhood trauma exposure, specifically in terms of understanding how specific cognitive functions may be influenced and providing a clearer understanding of how psychopathic traits develop.

Research shows sibling relationships can influence cognitive development, specifically in terms of high-order processes involved in social functioning. These high-order processes take place in the human prefrontal cortex. While prefrontal connectivity can be influenced by factors experienced during developmental phases, it remains unclear how experiences of aggression towards a sibling in childhood can contribute to high-order processes in adulthood, specifically decision-making. Through two studies, we sought to establish a relationship between sibling aggression and decision-making styles reported in adulthood, as well as real-time risky decision-making. Study 1 examined the relationship between childhood experiences of sibling aggression and high-order function, specifically decision-making. Self-reports from 142 adult participants revealed that using sibling aggression to maintain dominance (ESAS; Harrison, 2017) was linked to avoidant and spontaneous decision-making (GDMS; Scott & Bruce, 1995). The findings reported here indicate a possible role of sibling aggression in the development of avoidant and spontaneous decision-making styles. Study 2 investigated the relationship between childhood sibling aggression (ESAS; Harrison, 2017) and performance in risky decision-making tasks (IOWA gambling task; Bechara et al., 2000) among 75 adult participants. It revealed that experiences of sibling aggression did not predict risky decision-making. These findings indicate that the types of decisions made may be influenced by childhood sibling aggression, but not the level of risk involved in decisions made.