Default Network Deactivations Are Correlated with Psychopathic Personality Traits

Background: The posteromedial cortex (PMC) and medial prefrontal cortex (mPFC) are part of a network of brain regions that has been found to exhibit decreased activity during goal-oriented tasks. This network is thought to support a baseline of brain activity, and is commonly referred to as the ‘‘default network’’. Although recent reports suggest that the PMC and mPFC are associated with affective, social, and self-referential processes, the relationship between these default network components and personality traits, especially those pertaining to social context, is poorly understood. Methodology/Principal Findings: In the current investigation, we assessed the relationship between PMC and mPFC deactivations and psychopathic personality traits using fMRI and a self-report measure. We found that PMC deactivations predicted traits related to egocentricity and mPFC deactivations predicted traits related to decision-making. Conclusions/Significance: These results suggest that the PMC and mPFC are associated with processes involving selfrelevancy and affective decision-making, consistent with previous reports. More generally, these findings suggest a link between default network activity and personality traits

Patterns of mitochondrial DNA instability in Brassica campestris cultured cells

We previously showed that the mitochondrial DNA (mtDNA) of a Brassica campestris callus culture had undergone extensive rearrangements (i.e. large inversions and a duplication) relative to DNA of the control plant [54]. In this study we observed that after continued growth, the mtDNA of this culture continues to change, with rearranged forms amplifying and diminishing to varying proportions. Strikingly similar changes were detected in the mtDNA profiles of a variety of other long- and short-term callus and cell suspension lines. However, the proportions of parental (‘unrearranged’) and novel (‘rearranged’) forms varied in different cultured cell mtDNAs. To address the source of this heterogeneity, we compared the mtDNA organization of 28 individual plants from the parental seed stock. With the exception of one plant containing high levels of a novel plasmid-like mtDNA molecule, no significant variation was detected among individual plants and therefore source plant variation is unlikely to have contributed to the diversity of mitochondrial genomes observed in cultured cells. The source of this culture-induced heterogeneity was also investigated in 16 clones derived from single protoplasts. A mixed population of unrearranged and rearranged mtDNA molecules was apprent in each protoclone, suggesting that the observed heterogeneity in various cultures might reflect the genomic composition of each individual cell; however, the induction of an intercellular heterogeneity subsequent to the protoplast isolation was not tested and therefore cannot be ruled out. The results of this study support our earlier model that the rapid structural alteration of B. campestris mtDNA in vitro results from preferential amplification and reassortment of minor pre-existing forms of the genome rather than de novo rearrangement. Infrequent recombination between short dispersed repeated elements is proposed as the underlying mechanism for the formation of these minor mtDNA molecules.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43428/1/11103_2004_Article_BF00017914.pd

Mourning and melancholia revisited: correspondences between principles of Freudian metapsychology and empirical findings in neuropsychiatry

Freud began his career as a neurologist studying the anatomy and physiology of the nervous system, but it was his later work in psychology that would secure his place in history. This paper draws attention to consistencies between physiological processes identified by modern clinical research and psychological processes described by Freud, with a special emphasis on his famous paper on depression entitled 'Mourning and melancholia'. Inspired by neuroimaging findings in depression and deep brain stimulation for treatment resistant depression, some preliminary physiological correlates are proposed for a number of key psychoanalytic processes. Specifically, activation of the subgenual cingulate is discussed in relation to repression and the default mode network is discussed in relation to the ego. If these correlates are found to be reliable, this may have implications for the manner in which psychoanalysis is viewed by the wider psychological and psychiatric communities