Adaptive coding in the human brain: Distinct object features are encoded by overlapping voxels in frontoparietal cortex.

Our ability to flexibly switch between different tasks is a key component of cognitive control. Non-human primate (NHP) studies (e.g., Freedman, Riesenhuber, Poggio, & Miller, 2001) have shown that prefrontal neurons are re-used across tasks, re-configuring their responses to code currently relevant information. In a similar vein, in the human brain, the "multiple demand" (MD) system is suggested to exert control by adjusting its responses, selectively processing information in line with our current goals (Duncan, 2010). However, whether the same or different resources (underlying neural populations) in the human brain are recruited to solve different tasks remains elusive. In the present study, we aimed to bridge the gap between the NHP and human literature by examining human functional imaging data at an intermediate level of resolution: quantifying the extent to which single voxels contributed to multiple neural codes. Participants alternated between two tasks requiring the selection of feature information from two distinct sets of objects. We examined whether neural codes for the relevant stimulus features in the two different tasks depended on the same or different voxels. In line with the electrophysiological literature, MD voxels were more likely to contribute to multiple neural codes than we predicted based on permutation tests. Comparatively, in the visual system the neural codes depended on distinct sets of voxels. Our data emphasise the flexibility of the MD regions to re-configure their responses and adaptively code relevant information across different tasks

An evaluation of the Black Country in Motion: a community led intervention for the engagement of hard to reach, physically inactive communities of the Black Country

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of PhilosophyPhysical activity has been associated with reducing the risk of poor health and improving health and wellbeing. However contrary to this knowledge, physical activity levels remain significantly low with an estimate of 20 million adults being inactive in the UK (BHF, 2017), the cost of which is a suggested £2.8 billion per year to the UK’s economy. Subsequently, those who experience socio-economic disadvantage are more inclined to be inactive. As a means to tackling inactivity within such demographic groups, community-led interventions have been used to engage individuals and increase social cohesion and social capital. However the challenges experienced in measuring the efficacy, effectiveness and impact of real world community intervention have been well documented. Objectives - To evaluate the effectiveness of a community based, community-led physical activity intervention aimed at increasing physical activity Intervention - The Black Country in Motion (BCiM) is a 3 year programme, delivered in areas of high socioeconomic disadvantage in the Black Country area of the West Midlands. UK. The intervention aimed to increase physical activity, wellbeing and social capital. Design of the Evaluation - This evaluation uses a mixed-methods approach comprising of measuring physical activity using the International Physical Activity Questionnaire, the examination of change through qualitative analysis (based upon the Transtheoretical model for behaviour change framework), examining volunteerism in these communities and the volunteering physical activity facilitators and process evaluation. Setting - Community facilities and leisure centres in the Black Country Area of the West Midlands, UK Participants - Over a 3 year period, n=1205 participants had registered with the BCiM programme, at the point of analysis n=991 had engaged with the programme. Ages ranged from 12- 84 years and from across the Black Country region. 39.1% (n=387) were male and 60.9% (n=604) female participants. The objective of the intervention was to increase the physical activity of these participants, this was measured using the International Physical Activity Questionnaire and through semi-structured interview. Interviews identified the processes of change and psychosocial variables that impacted engagement adherence/drop out. Volunteers - A total of one hundred and forty four volunteers were recruited to deliver physical activity, of whom 22 were interviewed examining narratives and experiences throughout the delivery of the programme. Volunteers were aged 19-62 (SD = 32), 14 females and 8 males. Measuring Behaviour Change and Outcome Evaluation - Quantitative Measures - All participants completed a single item measure at baseline and were required to complete the International Physical Activity Questionnaire (IPAQ) to determine physical activity levels. This was a predetermined measure from funders and measured the duration and intensity of activity. Physical activity was measured at baseline, 3, 6 and 12 month follow ups. Drop out in the research process was significant and at the point of analysis n=73 participants had completed this measure. Qualitative Measures - To determine the effectiveness of the community-led intervention, 5 case studies (including interview data from 11 engaged participants and 12 disengaged participants), examined the processes of change, project efficacy and the psychosocial variables that impacted community engagement. Process Evaluation - A number of physical activity sessions were delivered as planned. Recruitment was challenging and the original target number of participants was not reached at the point of project completion. At the point of analysis, the reach of the project had engaged 991 participants, 36.1% (n=358) of those that had registered and attended at least one physical activity session resided in the target areas of this intervention. The efficacy of the programme was not delivered as intended and the sustainability of sessions was affected by low attendance and attrition. Volunteerism and the Community Volunteer - With current sport policy rhetoric including volunteering and the voluntary sectors impact on sport and physical activity delivery. This thesis examines community volunteering. One hundred and forty-four volunteers were recruited for the delivery of physical activity in this intervention. Drawing on this intervention’s emphasis on community and community volunteering, the principles of volunteerism were explored within these communities. Using semi-structured interviews, the narratives of those who volunteered in the BCiM were examined to identify the impact of this community intervention on developing social capital and community cohesion. Conclusion - The Black Country in Motion was effective in facilitating and enabling social mobility and increases in physical activity with those who were inactive prior to engagement and adhered to the programme. Those that had disengaged from the programme had suggested that the intensity of exercise delivered was challenging and in some instances subsequently sought alternative provision. It is argued that this may be a result of inexperience of the volunteers in their inability to differentiate activities and intensity. Those that were engaged discussed the social bonds that were developed and reaffirmed through their engagement in their communities, however these social bonds were fragile, as experiences within a community were relative to the individual. It is suggested that further investigation in recruitment and retention is required.Black Country BeActiv

Concurrent neuroimaging and neurostimulation reveals a causal role for dlPFC in coding of task-relevant information.

Dorsolateral prefrontal cortex (dlPFC) is proposed to drive brain-wide focus by biasing processing in favour of task-relevant information. A longstanding debate concerns whether this is achieved through enhancing processing of relevant information and/or by inhibiting irrelevant information. To address this, we applied transcranial magnetic stimulation (TMS) during fMRI, and tested for causal changes in information coding. Participants attended to one feature, whilst ignoring another feature, of a visual object. If dlPFC is necessary for facilitation, disruptive TMS should decrease coding of attended features. Conversely, if dlPFC is crucial for inhibition, TMS should increase coding of ignored features. Here, we show that TMS decreases coding of relevant information across frontoparietal cortex, and the impact is significantly stronger than any effect on irrelevant information, which is not statistically detectable. This provides causal evidence for a specific role of dlPFC in enhancing task-relevant representations and demonstrates the cognitive-neural insights possible with concurrent TMS-fMRI-MVPA

Concurrent neuroimaging and neurostimulation reveals a causal role for dlPFC in coding of task-relevant information.

Dorsolateral prefrontal cortex (dlPFC) is proposed to drive brain-wide focus by biasing processing in favour of task-relevant information. A longstanding debate concerns whether this is achieved through enhancing processing of relevant information and/or by inhibiting irrelevant information. To address this, we applied transcranial magnetic stimulation (TMS) during fMRI, and tested for causal changes in information coding. Participants attended to one feature, whilst ignoring another feature, of a visual object. If dlPFC is necessary for facilitation, disruptive TMS should decrease coding of attended features. Conversely, if dlPFC is crucial for inhibition, TMS should increase coding of ignored features. Here, we show that TMS decreases coding of relevant information across frontoparietal cortex, and the impact is significantly stronger than any effect on irrelevant information, which is not statistically detectable. This provides causal evidence for a specific role of dlPFC in enhancing task-relevant representations and demonstrates the cognitive-neural insights possible with concurrent TMS-fMRI-MVPA

Spatial scale and distribution of neurovascular signals underlying decoding of orientation and eye of origin from fMRI data

Multivariate pattern analysis of functional magnetic resonance imaging (fMRI) data is widely used, yet the spatial scales and origin of neurovascular signals underlying such analyses remain unclear. We compared decoding performance for stimulus orientation and eye of origin from fMRI measurements in human visual cortex with predictions based on the columnar organization of each feature and estimated the spatial scales of patterns driving decoding. Both orientation and eye of origin could be decoded significantly above chance in early visual areas (V1–V3). Contrary to predictions based on a columnar origin of response biases, decoding performance for eye of origin in V2 and V3 was not significantly lower than that in V1, nor did decoding performance for orientation and eye of origin differ significantly. Instead, response biases for both features showed large-scale organization, evident as a radial bias for orientation, and a nasotemporal bias for eye preference. To determine whether these patterns could drive classification, we quantified the effect on classification performance of binning voxels according to visual field position. Consistent with large-scale biases driving classification, binning by polar angle yielded significantly better decoding performance for orientation than random binning in V1–V3. Similarly, binning by hemifield significantly improved decoding performance for eye of origin. Patterns of orientation and eye preference bias in V2 and V3 showed a substantial degree of spatial correlation with the corresponding patterns in V1, suggesting that response biases in these areas originate in V1. Together, these findings indicate that multivariate classification results need not reflect the underlying columnar organization of neuronal response selectivities in early visual areas. NEW & NOTEWORTHY Large-scale response biases can account for decoding of orientation and eye of origin in human early visual areas V1–V3. For eye of origin this pattern is a nasotemporal bias; for orientation it is a radial bias. Differences in decoding performance across areas and stimulus features are not well predicted by differences in columnar-scale organization of each feature. Large-scale biases in extrastriate areas are spatially correlated with those in V1, suggesting biases originate in primary visual cortex

Promising-ARM/RISC-V: A Simpler and Faster Operational Concurrency Model

For ARMv8 and RISC-V, there are concurrency models in two styles, extensionally equivalent: axiomatic models, expressing the concurrency semantics in terms of global properties of complete executions; and operational models, that compute incrementally. The latter are in an abstract microarchitectural style: they execute each instruction in multiple steps, out-of-order and with explicit branch speculation. This similarity to hardware implementations has been important in developing the models and in establishing confidence, but involves complexity that, for programming and model-checking, one would prefer to avoid. We present new more abstract operational models for ARMv8 and RISC-V, and an exploration tool based on them. The models compute the allowed concurrency behaviours incrementally based on thread-local conditions and are significantly simpler than the existing operational models: executing instructions in a single step and (with the exception of early writes) in program order, and without branch speculation. We prove the models equivalent to the existing ARMv8 and RISC-V axiomatic models in Coq. The exploration tool is the first such tool for ARMv8 and RISC-V fast enough for exhaustively checking the concurrency behaviour of a number of interesting examples. We demonstrate using the tool for checking several standard concurrent datastructure and lock implementations, and for interactively stepping through model-allowed executions for debugging.EP/K008528/

Activity-driven relaxation of the cortical actomyosin II network synchronizes Munc18-1-dependent neurosecretory vesicle docking

In neurosecretory cells, secretory vesicles (SVs) undergo Ca2(+)-dependent fusion with the plasma membrane to release neurotransmitters. How SVs cross the dense mesh of the cortical actin network to reach the plasma membrane remains unclear. Here we reveal that, in bovine chromaffin cells, SVs embedded in the cortical actin network undergo a highly synchronized transition towards the plasma membrane and Munc18-1-dependent docking in response to secretagogues. This movement coincides with a translocation of the cortical actin network in the same direction. Both effects are abolished by the knockdown or the pharmacological inhibition of myosin II, suggesting changes in actomyosin-generated forces across the cell cortex. Indeed, we report a reduction in cortical actin network tension elicited on secretagogue stimulation that is sensitive to myosin II inhibition. We reveal that the cortical actin network acts as a 'casting net' that undergoes activity-dependent relaxation, thereby driving tethered SVs towards the plasma membrane where they undergo Munc18-1-dependent docking