The Associative Mechanism & Neural Correlates of Pavlovian-Instrumental Transfer in Humans

The ability to adapt to a changing environment requires the ability to extract predictive information to guide future action. Predictive information regarding the relationship between the performance of an action, or some external stimulus, and the delivery of a rewarding outcome can influence behaviour. Additionally, these processes can interact; reward-predictive stimuli can influence action-selection and guide choice, effects that can be examined in the laboratory using tests of Pavlovian-instrumental transfer (PIT). In these tests, a stimulus associated with a specific outcome biases action-selection towards actions previously been associated with that same outcome (specific transfer – sPIT) whereas a stimulus predicting an outcome not earned by any action can increase the vigour of instrumental responding (general transfer – gPIT). This thesis examines the psychological and neural processes that underlie the expression of PIT in humans. Although extensive research in rodents has attempted to clarify the mechanism through which independently trained Pavlovian stimuli are able to influence action, and the neural circuitry involved in the expression of this effect, to date there has been limited research investigating PIT in humans. To address this, a behavioural task adapted from the rodent literature was used to examine the influence of Pavlovian stimuli on both sPIT and gPIT; i.e., on the effects of predictive stimuli on response bias and response vigour in a comparable manner to the established research in rodents

Becoming Librarian OER Advocates & Leaders: Spotlight on the SPARC Open Education Leadership Fellows

Presentation given at the 15th Annual Open Education Conference in Niagara Falls, New York

Nowhere to escape – Diversity and community composition of ferns and lycophytes on the highest mountain in Honduras

IPCC predictions for Honduras indicate that temperature will increase by up to 3–6°C and precipitation will decrease by up to 7–13% by the year 2050. To better understand how fern and lycophyte communities might be affected by climate change, we comprehensively surveyed the community compositions of ferns and lycophytes at Celaque National Park, the highest mountain in Honduras. We surveyed a total of 80 20 × 20 m2 plots along an altitudinal gradient of 1249–2844 m a.s.l., identifying all species and estimating their abundances. We recorded a total of 11,098 individuals from 160 species and 61 genera. Community composition was strongly influenced by changes in altitude, precipitation and the abundance of bryophytes (a proxy for air humidity). Of the 160 species, 63 are expected, under a RCP2.6 scenario for the year 2050, to shift their range fully or partially above the maximum altitude of the mountain. Of these, 65.1% are epiphytes. We found that species with narrow altitudinal ranges at high altitudes were more at risk. Our study indicated that conservation efforts should prioritise higher altitudinal sites, focusing particularly on preserving the vulnerable epiphytic fern species, which are likely to be at greater risk

The truth project paper one—how did victims and survivors experience participation? Addressing epistemic relational inequality in the field of child sexual abuse

The last 30 years has seen an exponential increase in Historical Institutional Abuse Inquiries.1 One feature of these has been to place adult survivor voices at the center of Inquiry work, meaning that child abuse victims and survivors2 are engaging with Inquiries, sharing their experiences, with this participation often presented as empowering and healing. This initiative challenges long held beliefs that child sexual abuse survivors are unreliable witnesses, which has led to epistemic injustice and a hermeneutical lacunae in survivor testimony. However to date there has been limited research on what survivors say about their experiences of participation. The Truth Project was one area of work of the Independent Inquiry into Child Sexual Abuse3 in England and Wales. It invited survivors of Child Sexual Abuse to share their experiences including the impacts of abuse and their recommendations for change. The Truth Project concluded in 2021 and heard from more than 6,000 victims of child sexual abuse. The evaluation of the Trauma Informed Approach designed to support survivors through their engagement with the project was a mixed methods, two phase methodology. A total of 66 survey responses were received. Follow-up interviews were conducted with seven survey respondents. The Trauma Informed Approach was found to be predominantly helpful in attending to victim needs and minimizing harm. However, a small number of participants reported harmful effects post-session. The positive impacts reported about taking part in the Truth Project as a one-off engagement challenges beliefs that survivors of child sexual abuse cannot safely talk about their experiences. It also provides evidence of the central role survivors should have in designing services for trauma victims. This study contributes to the epistemic justice literature which emphasizes the central role of relational ethics in the politics of knowing, and the importance of developing a testimonial sensibility when listening to marginalized groups

Determining the effects of training duration on the behavioral expression of habitual control in humans: a multi-laboratory investigation

It has been suggested that there are two distinct and parallel mechanisms for controlling instrumental behavior in mammals: goal-directed actions and habits. To gain an understanding of how these two systems interact to control behavior, it is essential to characterize the mechanisms by which the balance between these systems is influenced by experience. Studies in rodents have shown that the amount of training governs the relative expression of these two systems: behavior is goal-directed following moderate training, but the more extensively an instrumental action is trained, the more it becomes habitual. It is less clear whether humans exhibit similar training effects on the expression of goal-directed and habitual behavior, as human studies have reported contradictory findings. To tackle these contradictory findings, we formed a consortium, where four laboratories undertook a pre-registered experimental induction of habits by manipulating the amount of training. There was no statistical evidence for a main effect of the amount of training on the formation and expression of habits. However, exploratory analyses suggest a moderating effect of the affective component of stress on the impact of training over habit expression. Participants who were lower in affective stress appeared to be initially goal-directed, but became habitual with increased training, whereas participants who were high in affective stress were already habitual even after moderate training, thereby manifesting insensitivity to overtraining effects. Our findings highlight the importance of the role of moderating variables such as individual differences in stress and anxiety when studying the experimental induction of habits in humans

Comparative Genomics of the Apicomplexan Parasites Toxoplasma gondii and Neospora caninum: Coccidia Differing in Host Range and Transmission Strategy

Toxoplasma gondii is a zoonotic protozoan parasite which infects nearly one third of the human population and is found in an extraordinary range of vertebrate hosts. Its epidemiology depends heavily on horizontal transmission, especially between rodents and its definitive host, the cat. Neospora caninum is a recently discovered close relative of Toxoplasma, whose definitive host is the dog. Both species are tissue-dwelling Coccidia and members of the phylum Apicomplexa; they share many common features, but Neospora neither infects humans nor shares the same wide host range as Toxoplasma, rather it shows a striking preference for highly efficient vertical transmission in cattle. These species therefore provide a remarkable opportunity to investigate mechanisms of host restriction, transmission strategies, virulence and zoonotic potential. We sequenced the genome of N. caninum and transcriptomes of the invasive stage of both species, undertaking an extensive comparative genomics and transcriptomics analysis. We estimate that these organisms diverged from their common ancestor around 28 million years ago and find that both genomes and gene expression are remarkably conserved. However, in N. caninum we identified an unexpected expansion of surface antigen gene families and the divergence of secreted virulence factors, including rhoptry kinases. Specifically we show that the rhoptry kinase ROP18 is pseudogenised in N. caninum and that, as a possible consequence, Neospora is unable to phosphorylate host immunity-related GTPases, as Toxoplasma does. This defense strategy is thought to be key to virulence in Toxoplasma. We conclude that the ecological niches occupied by these species are influenced by a relatively small number of gene products which operate at the host-parasite interface and that the dominance of vertical transmission in N. caninum may be associated with the evolution of reduced virulence in this species

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant