Attention modulates contexual processing in vision

PhD ThesisContextual information influences the neuronal processing and perception of visual stimuli. The functional significance of this influence may be to increase the efficiency of visual processing by taking advantage of redundancies in natural scenes. Increased efficiency may come at a cost of introducing errors, especially when stimuli are incongruous with the context. For optimal performance the visual system may therefore balance efficiency with accuracy by dynamically controlling the influence of contextual information. Attention is an appropriate mechanism to set this balance since attention is high when errors are costly and therefore accuracy is preferable over efficiency, but attention is low when accuracy can be sacrificed for efficiency. States of attention are associated with increased acetylcholine (ACh) efflux into the cortex. The effect of ACh on cortical processing has been investigated in a number of in vitro studies. They show that ACh causes a selective inhibition of intracortical synapses while thalamocortical synapses are unaffected or even enhanced. Thus, ACh effectively switches cortical processing in favour of feedforward inputs. In the visual system this switching would be expected to reduce contextual influences, thought to be mediated by intracortical processing. These findings suggest the hypothesis that attention will reduce contextual influences by the action of ACh. To investigate this hypothesis I present work from four separate experiments. I found that attention caused a reduction in contextual influences at the level of human perception (Experiment 1) and at the level of neurons in primate V1 (Experiment 3). I also found the application of ACh to cells in VI of anaesthetised primates caused a reduction in non-classical receptive field modulation (Experiment 2), similar to the effect of attention. Finally I found that attentional modulation of neuronal responses in macaque V1 was partially blocked by the application of a cholinergic antagonist, scopolamine (Experiment 4). Taken together my findings demonstrate that attention causes a suppression of contextual influences at the level of perception and at the level of the primary visual cortex. These effects were at least partly mediated by cholinergic mechanisms.Medical Research Council studentship G78/7853, Wellcome grant GR070380, Biotechnology and Biological Sciences Research Council grant BBSB/09325, Royal Society small grant scheme 57400. G503/2936

Motive8!: feasibility of a text messaging intervention to promote physical activity in knee osteoarthritis

Aim: To develop and test the feasibility of using a SMS text messaging intervention to promote physical activity in patients with knee OA. Methods: 27 people (6 male, 21 female; aged 25-81 years) with knee osteoarthritis received 4 text messages per week, for 6 weeks. Telephone surveys were conducted at baseline and 6 weeks to measure physical activity levels and beliefs, including self-efficacy for exercise, barriers and benefits of exercise, social support and pain. Participants completed physical activity diaries. Process evaluation included participant perceptions of the intervention and 'real-time' data on intervention fidelity (automated collection of delivery and response data) and participant engagement (text response). Results: 648 messages were sent, 100% were accurately delivered. From baseline to 6 weeks, physical activity, self-efficacy for exercise, perceived benefits of exercise and social support significantly increased; reductions were observed in barriers to exercise and pain. Participants engaged with the intervention; 100% read the messages, 89% responded to texts requesting replies, 64% completed physical activity diaries with low attenuation (1.8% drop) by six weeks. Participants perceived messaging to be enjoyable (96%), personally relevant (85%), of appropriate frequency (100%) and duration (88%). Mobile phones, email and web were perceived to be most acceptable for health promotion compared with other forms of technology. Conclusions: People with knee osteoarthritis can engage meaningfully with an interactive mobile phone messaging intervention over a six-week period. Health communications promoting physical activity demonstrate potential for behaviour change and positive implications for perceptions of exercise and pain; this needs to be tested in a randomised trial. Data collected in 'real-time' can be used for process evaluation to demonstrate participant engagement and intervention fidelity

Risk factors and comorbidity of ICD?11 PTSD and complex PTSD: Findings from a trauma?exposed population based sample of adults in the United Kingdom

Background: Following the recently published 11th version of the WHO International Classification of Diseases (ICD-11), we sought to examine the risk factors and comorbidities associated with posttraumatic stress disorder (PTSD) and Complex PTSD (CPTSD). Method: Cross-sectional and retrospective design. The sample consisted of 1051 trauma-exposed participants from a nationally representative panel of the UK adult population. Results: 5.3% (95% CI = 4.0%-6.7%) met the diagnostic criteria for PTSD and 12.9% (95% CI = 10.9%-15.0%) for CPTSD. Diagnosis of PTSD was independently associated with being female, being in a relationship, and the recency of traumatic exposure. CPTSD was independently associated with younger age, interpersonal trauma in childhood, and interpersonal trauma in adulthood. Growing up in an urban environment was associated with diagnosis of PTSD and CPTSD. High rates of physical and mental health comorbidity were observed for PTSD and CPTSD. Those with CPTSD were more likely to endorse symptoms reflecting Major Depressive Disorder (OR = 21.85, 95 CI = 12.51 – 38.04) and Generalized Anxiety Disorder (OR = 24.63, 95 CI = 14.77 – 41.07). Presence of PTSD (OR = 3.13, 95 CI = 1.81 – 5.41) and CPTSD (OR = 3.43, 95 CI = 2.37 – 4.70) increased the likelihood of suicidality by more than three times. Nearly half the participants with PTSD and CPTSD reported the presence of a chronic illness. Conclusions: CPTSD is a more common, co-morbid, debilitating condition compared PTSD. Further research is now required to identify effective interventions for its treatment

Variability in the summer movements, habitat use and thermal biology of two fish species in a temperate river

The ability of fish to cope with warm water temperatures in summer depends on factors including their thermal traits and the ability of individuals to access cool-water refugia. Knowledge is highly limited on the in situ responses of many fishes to elevated summer temperatures, including whether they express behavioural thermoregulation. The responses of two riverine species to summer water temperatures were tested here using the movement metrics, spatial habitat use and body temperatures of individual European barbel Barbus barbus (‘barbel’) and common bream Abramis brama (‘bream’) versus river temperatures. Acoustic biotelemetry was applied in the lower River Severn basin, western Britain, in summer 2021 (barbel) and 2022 (bream), where individuals could move across > 150 km of river, including a tributary of cooler water. Across all individuals, bream occupied 37 km of river length (mainstem only), with low inter-individual variability in their spatial habitat use, movements and body temperatures. In contrast, barbel occupied 62 km of river (main river/tributary), with relatively high inter-individual variability in spatial habitat use, movements and body temperatures, with higher variation in body temperatures as river temperatures increased (maximum mean daily temperature difference between individuals on the same day: 4.2 °C). Although warmer individuals generally moved more, their activity was greatest at relatively low temperatures and higher flows, and neither species revealed any evidence of behavioural thermoregulation during elevated temperatures. Enabling phenotypically diverse fish populations to express their natural behaviours and thermal preferences in summer water temperatures thus requires maintaining their free-ranging in thermally heterogenous habitats

Nutritional skewing of conceptus sex in sheep: effects of a maternal diet enriched in rumen-protected polyunsaturated fatty acids (PUFA)

<p>Abstract</p> <p>Background</p> <p>Evolutionary theory suggests that in polygynous mammalian species females in better body condition should produce more sons than daughters. Few controlled studies have however tested this hypothesis and controversy exists as to whether body condition score or maternal diet is in fact the determining factor of offspring sex. Here, we examined whether maternal diet, specifically increased n-6 polyunsaturated fatty acid (PUFA) intake, of ewes with a constant body condition score around the time of conception influenced sex ratio.</p> <p>Methods</p> <p>Ewes (n = 44) maintained in similar body condition throughout the study were assigned either a control (C) diet or one (F) enriched in rumen-protected PUFA, but otherwise essentially equivalent, from four weeks prior to breeding until d13 post-estrus. On d13, conceptuses were recovered, measured, cultured to assess their capacity for interferon-tau (IFNT) production and their sex determined. The experiment was repeated with all ewes being fed the F diet to remove any effects of parity order on sex ratio. Maternal body condition score (BCS), plasma hormone and metabolite concentrations were also assessed throughout the study and related to diet.</p> <p>Results</p> <p>In total 129 conceptuses were recovered. Ewes on the F diet produced significantly more male than female conceptuses (proportion male = 0.69; deviation from expected ratio of 0.5, P < 0.001). Conceptus IFNT production was unaffected by diet (P > 0.1), but positively correlated with maternal body condition score (P < 0.05), and was higher (P < 0.05) in female than male conceptuses after 4 h culture. Maternal plasma hormone and metabolite concentrations, especially progesterone and fatty acid, were also modulated by diet.</p> <p>Conclusion</p> <p>These results provide evidence that maternal diet, in the form of increased amounts of rumen-protected PUFA fed around conception, rather than maternal body condition, can skew the sex ratio towards males. These observations may have implications to the livestock industry and animal management policies when offspring of one sex may be preferred over the other.</p