Impaired goal-directed behavioural control in human impulsivity.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThis is the final version of the article. Available from Taylor & Francis (Routledge) via the DOI in this record.Two dissociable learning processes underlie instrumental behaviour. Whereas goal-directed behaviour is controlled by knowledge of the consequences, habitual behaviour is elicited directly by antecedent Pavlovian stimuli without knowledge of the consequences. Predominance of habitual control is thought to underlie psychopathological conditions associated with corticostriatal abnormalities, such as impulsivity and drug dependence. To explore this claim, smokers were assessed for nicotine dependence, impulsivity, and capacity for goal-directed control over instrumental performance in an outcome devaluation procedure. Reduced goal-directed control was selectively associated with the Motor Impulsivity factor of Barrett's Impulsivity Scale (BIS), which reflects propensity for action without thought. These data support the claim that human impulsivity is marked by impaired use of causal knowledge to make adaptive decisions. The predominance of habit learning may play a role in psychopathological conditions that are associated with trait impulsivity.This work was supported by an MRC grant to Lee Hogarth (G0701456) at the University of Nottingham

Alternative bacteriophage life cycles: the carrier state of Campylobacter jejuni

Members of the genus Campylobacter are frequently responsible for human enteric disease, often through consumption of contaminated poultry products. Bacteriophages are viruses that have the potential to control pathogenic bacteria, but understanding their complex life cycles is key to their successful exploitation. Treatment of Campylobacter jejuni biofilms with bacteriophages led to the discovery that phages had established a relationship with their hosts typical of the carrier state life cycle (CSLC), where bacteria and bacteriophages remain associated in equilibrium. Significant phenotypic changes include improved aerotolerance under nutrient-limited conditions that would confer an advantage to survive in extra-intestinal environments, but a lack in motility eliminated their ability to colonize chickens. Under these circumstances, phages can remain associated with a compatible host and continue to produce free virions to prospect for new hosts. Moreover, we demonstrate that CSLC host bacteria can act as expendable vehicles for the delivery of bacteriophages to new host bacteria within pre-colonized chickens. The CSLC represents an important phase in the ecology of Campylobacter bacteriophage

Attenuation of auditory ERPs to action-sound coincidences is not explained by voluntary allocation of attention

The event-related potential (ERP) correlates of sound detection are attenuated when eliciting sounds coincide with our own actions. The role of attention in this effect was investigated in two experiments by presenting tones separated by random intervals. In the Homogeneous Condition of Experiment 1 and in Experiment 2 the same tone was repeated, whereas in the Mixed Condition of Experiment 1 tones with five different frequencies were presented. Participants performed a time interval production task by marking intervals with key-presses in Experiment 1, and tried to produce key-press-tone coincidences in Experiment 2. Although the auditory ERPs were attenuated for coincidences, no modulation by the multiplicity of tone-frequencies in Experiment 1, or by the task-relevancy of tones and coincidences in Experiment 2 was found. This suggests that coincidence-related ERP attenuation cannot be fully explained by voluntary attentional mechanisms

No evidence for peripheral mechanism attenuating auditory ERPs to self-induced tones

The N1 and P2 event-related potentials (ERPs) are attenuated when the eliciting sounds coincide with our own actions. Although this ERP attenuation could be caused by central processes, it may also reflect a peripheral mechanism: the co-activation of the stapedius muscle with the task-relevant effector, which reduces signal transmission efficiency in the middle ear, reducing the effective intensity of concurrently presented tones, which, in turn, elicit lower-amplitude auditory ERPs. Because stapedius muscle contraction attenuates frequencies below 2 kHz, no attenuation should occur at frequencies above 2 kHz. A self-induced tone paradigm was administered with 0.5, 2.0, and 8.0 kHz pure tones. Self-induced tones elicited attenuated N1 and P2 ERPs, but the magnitude of attenuation was not affected by tone-frequency. This result does not support the hypothesis that ERP attenuation to self-induced tones are caused by stapedius muscle contractions

The effect of normal personality, psychopathy and attachment on anti-and prosocial outcomes

Psychopathy is a dangerous form of antisocial personality that is associated with aggressive and delinquent behaviour. This thesis investigated psychopathic traits in the normal population to assess the relationship to antisocial and prosocial behaviour. This was examined both psychometrically and behaviourally. Furthermore, it was examined if emotion-processing deficits existed between individuals with high and low psychopathic traits in the normal population. Study 1 examined if standard personality measures based on the Five-Factor Model (FFM) of Personality, as well as specific items aimed to index sub-clinical primary and secondary psychopathic traits, could predict psychopathy-related outcomes in 14 year olds. It was found that individuals with higher levels of Neuroticism (N) and lower levels of Conscientiousness (C) were at an increased risk of mental health problems. Higher levels of Extraversion (E) and lower levels of C were related to increased alcohol and drug use. Alcohol and drug use were also predicted by higher primary and secondary psychopathic-like traits. Study 2 examined alcohol use as well as both proactive and reactive aggression in relation to FFM traits and psychopathic traits in adolescents, and revealed that psychopathic traits were the best predictors of aggression. Alcohol use was best predicted by FFM traits at age 14. Study 3 was a replication of Study 2 using a young adult sample. Whereas alcohol use and proactive aggression were found to be best predicted by higher levels of psychopathic traits, as measured by the Youth Psychopathy Inventory, reactive aggression was most strongly predicted by high levels of N and low levels of Agreeableness (A). As it has been suggested that attachment may be an underlying mechanism involved in the deficits seen in psychopathic individuals, in the second part of the thesis it was assessed whether attachment plays a role in the relationship between psychopathy and emotion-processing as well as antisocial and prosocial behaviour. Study 4 confirmed psychometrically that psychopathy as measured by the YPI was related to attachment to parents as well as the dismissing-avoidant attachment style. Study 5 and 6 investigated the link between psychopathic traits and emotion-processing, prosocial and antisocial behaviour as well as the impact of attachment on these relationships. The results of these studies indicated that self-report psychopathy measures were related to antisocial outcomes psychometrically but failed to show predicted associations with prosocial and antisocial tendencies behaviourally. However, differences in emotion-processing were found between individuals with low and high levels of psychopathic traits. It was also found that FFM-based personality traits were useful in predicting psychopathy-related outcomes and can be effective in describing psychopathy-like traits. Finally, self-reported attachment did not impact the relationship between psychopathy and emotion-processing, antisocial and prosocial behaviour. These findings provide novel insight into the relationship between psychopathic traits and emotion-processing as well as antisocial and prosocial behaviour in the normal population, show the effectiveness of FFM traits in predicting psychopathy-related outcomes and highlight difficulties with regard to quantitative measures of attachment

The effect of normal personality, psychopathy and attachment on anti-and prosocial outcomes

Psychopathy is a dangerous form of antisocial personality that is associated with aggressive and delinquent behaviour. This thesis investigated psychopathic traits in the normal population to assess the relationship to antisocial and prosocial behaviour. This was examined both psychometrically and behaviourally. Furthermore, it was examined if emotion-processing deficits existed between individuals with high and low psychopathic traits in the normal population. Study 1 examined if standard personality measures based on the Five-Factor Model (FFM) of Personality, as well as specific items aimed to index sub-clinical primary and secondary psychopathic traits, could predict psychopathy-related outcomes in 14 year olds. It was found that individuals with higher levels of Neuroticism (N) and lower levels of Conscientiousness (C) were at an increased risk of mental health problems. Higher levels of Extraversion (E) and lower levels of C were related to increased alcohol and drug use. Alcohol and drug use were also predicted by higher primary and secondary psychopathic-like traits. Study 2 examined alcohol use as well as both proactive and reactive aggression in relation to FFM traits and psychopathic traits in adolescents, and revealed that psychopathic traits were the best predictors of aggression. Alcohol use was best predicted by FFM traits at age 14. Study 3 was a replication of Study 2 using a young adult sample. Whereas alcohol use and proactive aggression were found to be best predicted by higher levels of psychopathic traits, as measured by the Youth Psychopathy Inventory, reactive aggression was most strongly predicted by high levels of N and low levels of Agreeableness (A). As it has been suggested that attachment may be an underlying mechanism involved in the deficits seen in psychopathic individuals, in the second part of the thesis it was assessed whether attachment plays a role in the relationship between psychopathy and emotion-processing as well as antisocial and prosocial behaviour. Study 4 confirmed psychometrically that psychopathy as measured by the YPI was related to attachment to parents as well as the dismissing-avoidant attachment style. Study 5 and 6 investigated the link between psychopathic traits and emotion-processing, prosocial and antisocial behaviour as well as the impact of attachment on these relationships. The results of these studies indicated that self-report psychopathy measures were related to antisocial outcomes psychometrically but failed to show predicted associations with prosocial and antisocial tendencies behaviourally. However, differences in emotion-processing were found between individuals with low and high levels of psychopathic traits. It was also found that FFM-based personality traits were useful in predicting psychopathy-related outcomes and can be effective in describing psychopathy-like traits. Finally, self-reported attachment did not impact the relationship between psychopathy and emotion-processing, antisocial and prosocial behaviour. These findings provide novel insight into the relationship between psychopathic traits and emotion-processing as well as antisocial and prosocial behaviour in the normal population, show the effectiveness of FFM traits in predicting psychopathy-related outcomes and highlight difficulties with regard to quantitative measures of attachment

The bacteriophage carrier state of Campylobacter jejuni features changes in host non-coding RNAs and the acquisition of new host-derived CRISPR spacer sequences

Incorporation of self-derived CRISPR DNA protospacers in Campylobacter jejuni PT14 occurs in the presence of bacteriophages encoding a CRISPR-like Cas4 protein. This phenomenon was evident in carrier state infections where both bacteriophages and host are maintained for seemingly indefinite periods as stable populations following serial passage. Carrier state cultures of C. jejuni PT14 have greater aerotolerance in nutrient limited conditions, and may have arisen as an evolutionary response to selective pressures imposed during periods in the extra-intestinal environment. A consequence of this is that bacteriophage and host remain associated and able to survive transition periods where the chances of replicative success are greatly diminished. The majority of the bacteriophage population do not commit to lytic infection, and conversely the bacterial population tolerates low-level bacteriophage replication. We recently examined the effects of Campylobacter bacteriophage/C. jejuni PT14 CRISPR spacer acquisition using deep sequencing strategies of DNA and RNA-Seq to analyze carrier state cultures. This approach identified de novo spacer acquisition in C. jejuni PT14 associated with Class III Campylobacter phages CP8/CP30A but spacer acquisition was oriented toward the capture of host DNA. In the absence of bacteriophage predation the CRISPR spacers in uninfected C. jejuni PT14 cultures remain unchanged. A distinct preference was observed for incorporation of self-derived protospacers into the third spacer position of the C. jejuni PT14 CRISPR array, with the first and second spacers remaining fixed. RNA-Seq also revealed the variation in the synthesis of non-coding RNAs with the potential to bind bacteriophage genes and/or transcript sequences

Active inference, sensory attenuation and illusions.

Active inference provides a simple and neurobiologically plausible account of how action and perception are coupled in producing (Bayes) optimal behaviour. This can be seen most easily as minimising prediction error: we can either change our predictions to explain sensory input through perception. Alternatively, we can actively change sensory input to fulfil our predictions. In active inference, this action is mediated by classical reflex arcs that minimise proprioceptive prediction error created by descending proprioceptive predictions. However, this creates a conflict between action and perception; in that, self-generated movements require predictions to override the sensory evidence that one is not actually moving. However, ignoring sensory evidence means that externally generated sensations will not be perceived. Conversely, attending to (proprioceptive and somatosensory) sensations enables the detection of externally generated events but precludes generation of actions. This conflict can be resolved by attenuating the precision of sensory evidence during movement or, equivalently, attending away from the consequences of self-made acts. We propose that this Bayes optimal withdrawal of precise sensory evidence during movement is the cause of psychophysical sensory attenuation. Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly. Finally, if attenuation is removed, the force-matching illusion disappears and false (delusional) inferences about agency emerge. This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia. Active inference therefore links the neuromodulatory optimisation of precision to sensory attenuation and illusory phenomena during the attribution of agency in normal subjects. It also provides a functional account of deficits in syndromes characterised by false inference and impaired movement--like schizophrenia and Parkinsonism--syndromes that implicate abnormal modulatory neurotransmission

Sharing Different Reference Frames: How Stimulus Setup and Task Setup Shape Egocentric and Allocentric Simon Effects

Different reference frames are used in daily life in order to structure the environment. The two-choice Simon task setting has been used to investigate how task-irrelevant spatial information influences human cognitive control. In recent studies, a Go/NoGo Simon task setting was used in order to divide the Simon task between a pair of participants. Yet, not only a human co-actor, but also even an attention-grabbing object can provide sufficient reference in order to reintroduce a Simon effect (SE) indicating cognitive conflict in Go/NoGo task settings. Interestingly, the SE could only occur when a reference point outside of the stimulus setup was available. The current studies exploited the dependency between different spatial reference frames (egocentric and allocentric) offered by the stimulus setup itself and the task setup (individual vs. joint Go/NoGot task setting). Two studies (Experiments 1 and 2) were carried out along with a human co-actor. Experiment 3 used an attention-grabbing object instead. The egocentric and allocentric SEs triggered by different features of the stimulus setup (global vs. local) were modulated by the task setup. When interacting with a human co-actor, an egocentric SE was found for global features of the stimulus setup (i.e., stimulus position on the screen). In contrast, an allocentric SE was yielded in the individual task setup illustrating the relevance of more local features of the stimulus setup (i.e., the manikin’s ball position). Results point toward salience shifts between different spatial reference frames depending on the nature of the task setup