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Prof Robin Dunbar, Emeritus Professor of Evolutionary Psychology has been in conversation with Jim Al-Khalili on Radio 4's Life Scientific. This fascinating podcast gives takes us on a journey from his early beginnings in science, and his fascinating research and groundbreaking discoveries he's made deciphering the mysteries as to why humans and animals evolve the social habits to exist in friendship circles.
Evaluation of an adaptation to the Oxford Cognitive Screen for reduced visual acuity: a cohort study.
BACKGROUND: The Oxford Cognitive Screen (OCS) was specifically designed for acute stroke survivors and to be inclusive of aphasia, neglect, motor impairments. However, reduced visual acuity (VA), including lack of access to required reading glasses, can impact completion rates and performance. The aim of the study was to evaluate contrast enhanced OCS-tasks for completion rates and equivalence to the original version. METHODS: Adult stroke survivors were asked to complete two versions (standard and adapted) of two tasks (broken hearts cancellation and trails) in a randomized order, to determine relative completion rates and equivalency. A bedside vision assessment, completed by an orthoptist was collected, including near and distance VA with required refractive correction if available. Two groups were created based on near VA; normal near VA (≥0.2LogMAR) and reduced near VA (<0.2LogMAR). RESULTS: Five hundred participants were recruited, 56.8% male, mean age 70.62 years. Mean near VA was 0.278 (SD0.277) LogMAR. The broken hearts and trails tasks were completed by 2.2% (p=0.041) and 0.4% (p=0.791) more participants respectively with the adapted version. Participants completing both versions with good near VA were used to analyze equivalence. All the lower and upper bounds of the two one-sided test of equivalence fell within the range of 0.5SD for all scores, indicating that the means are equivalent. Analysis of impairment detection revealed fair to good agreement. CONCLUSION: The adapted version is suitable for stroke survivors with reduced near VA to complete the assessment. In the presence of good VA, the tasks were deemed to be equivalent.
Distinct epicardial gene regulatory programs drive development and regeneration of the zebrafish heart.
Unlike the adult mammalian heart, which has limited regenerative capacity, the zebrafish heart fully regenerates following injury. Reactivation of cardiac developmental programs is considered key to successfully regenerating the heart, yet the regulation underlying the response to injury remains elusive. Here, we compared the transcriptome and epigenome of the developing and regenerating zebrafish epicardia. We identified epicardial enhancer elements with specific activity during development or during adult heart regeneration. By generating gene regulatory networks associated with epicardial development and regeneration, we inferred genetic programs driving each of these processes, which were largely distinct. Loss of Hif1ab, Nrf1, Tbx2b, and Zbtb7a, central regulators of the regenerating epicardial network, in injured hearts resulted in elevated epicardial cell numbers infiltrating the wound and excess fibrosis after cryoinjury. Our work identifies differences between the regulatory blueprint deployed during epicardial development and regeneration, underlining that heart regeneration goes beyond the reactivation of developmental programs.
Extensive N4 cytosine methylation is essential for Marchantia sperm function
N4-methylcytosine (4mC) is an important DNA modification in prokaryotes, but its relevance and even its presence in eukaryotes have been mysterious. Here we show that spermatogenesis in the liverwort Marchantia polymorpha involves two waves of extensive DNA methylation reprogramming. First, 5-methylcytosine (5mC) expands from transposons to the entire genome. Notably, the second wave installs 4mC throughout genic regions, covering over 50% of CG sites in sperm. 4mC requires a methyltransferase (MpDN4MT1a) that is specifically expressed during late spermiogenesis. Deletion of MpDN4MT1a alters the sperm transcriptome, causes sperm swimming and fertility defects, and impairs post-fertilization development. Our results reveal extensive 4mC in a eukaryote, identify a family of eukaryotic methyltransferases, and elucidate the biological functions of 4mC in reproductive development, thereby expanding the repertoire of functional eukaryotic DNA modifications.
Exploiting social traits for clinical applications in bacteria and viruses.
Despite generating a great deal of interest in the form of review papers, progress in exploiting social dynamics for treatment strategies against bacterial infection has made limited progress since it was suggested twenty years ago. In contrast, anti-viral strategies based on social interactions are entering clinical trial stage. We explore possible reasons for this difference and highlight areas where the two fields of research may learn from one another.
A Guided Tour of Phylogenetic Comparative Methods for Studying Trait Evolution
Phylogenetic comparative methods are important tools in biology, providing insights into the way traits evolve. There are many technical resources describing how these methods work. Our aim here is to complement these with an overview of the types of biological questions that can be addressed by different methods and to outline potential pitfalls and considerations when embarking on comparative studies. First, we introduce what comparative methods are and why they are important. Second, we outline how they can be used to understand when, where, and how frequently traits evolve. Third, we examine how the coevolution of traits within and between species can be studied, along with patterns of causality. Finally, we discuss how to approach comparative analyses and the ways in which different types of data, such as published relationships, omic, and remote sensing data, can be integrated.
Focusing attention in working and long-term memory through dissociable mechanisms.
We developed an experimental approach to compare how attentional orienting facilitates retrieval from spatial working memory (WM) and long-term memory (LTM), and how selective attention within these two memory types impacts incoming sensory information processing. In three experiments with healthy young adults, retrospective attention cues prioritize an item represented in WM or LTM. Participants then retrieve a memory item or perform a perceptual task. The retrocue is informative for the retrieval task but not for the perceptual task. We show that attentional orienting benefits performance for both WM and LTM, with stronger effects for WM. Eye-tracking reveals significant gaze shifts and microsaccades correlated with attention in WM, but no statistically significant gaze biases were found for LTM. Visual discrimination of unrelated visual stimuli is consistently improved for items matching attended WM locations. Similar effects occur at LTM locations but less consistently. The findings suggest at least partly dissociable attention-orienting processes for different memory types. Although our conclusions are necessarily constrained to the type of WM and LTM representations relevant to our task, they suggest that, under certain conditions, attentional prioritization in LTM can operate independently from WM. Future research should explore whether similar dissociations extend to non-spatial or more complex forms of LTM.
Truthful communication of mental science: pledge to our patients and profession.
Recent changes in US government priorities have serious negative implications for science that will compromise the integrity of mental health research, which focuses on vulnerable populations. Therefore, as editors of mental science journals and custodians of the academic record, we confirm with conviction our collective commitment to communicating the truth.
Increased TMEM106B levels lead to lysosomal dysfunction which affects synaptic signaling and neuronal health
Background: Genetic variation in Transmembrane protein 106B (TMEM106B) is known to influence the risk and presentation in several neurodegenerative diseases and modifies healthy aging. While evidence from human studies suggests that the risk allele is associated with higher levels of TMEM106B, the contribution of elevated levels of TMEM106B to neurodegeneration and aging has not been assessed and it remains unclear how TMEM106B modulates disease risk. Methods: To study the effect of increased TMEM106B levels, we generated Cre-inducible transgenic mice expressing human wild-type TMEM106B. We evaluated lysosomal and neuronal health using in vitro and in vivo assays including transmission electron microscopy, immunostainings, behavioral testing, electrophysiology, and bulk RNA sequencing. Results: We created the first transgenic mouse model that successfully overexpresses TMEM106B, with a 4- to 8-fold increase in TMEM106B protein levels in heterozygous (hTMEM106B(+)) and homozygous (hTMEM106B(++)) animals, respectively. We showed that the increase in TMEM106B protein levels induced lysosomal dysfunction and age-related downregulation of genes associated with neuronal plasticity, learning, and memory. Increased TMEM106B levels led to altered synaptic signaling in 12-month-old animals which further exhibited an anxiety-like phenotype. Finally, we observed mild neuronal loss in the hippocampus of 21-month-old animals. Conclusion: Characterization of the first transgenic mouse model that overexpresses TMEM106B suggests that higher levels of TMEM106B negatively impacts brain health by modifying brain aging and impairing the resilience of the brain to the pathomechanisms of neurodegenerative disorders. This novel model will be a valuable tool to study the involvement and contribution of increased TMEM106B levels to aging and will be essential to study the many age-related diseases in which TMEM106B was genetically shown to be a disease- and risk-modifier.
Phase-dependent closed-loop deep brain stimulation of the fornix provides bidirectional manipulation of hippocampal theta oscillations.
INTRODUCTION: Alzheimer's disease (AD) has very limited treatment options and therapies to prevent or reverse neurodegeneration remain elusive. Deep brain stimulation (DBS), whereby high-frequency pulses of electricity are delivered continuously to a specific part of the brain, has been trialled as an experimental treatment for AD. In AD patients, continuous, high frequency DBS targeted to the fornix (fx-DBS) has been shown to be safe, but not reliably effective across patients. In movement disorders, high-frequency DBS is thought to act as a virtual lesion, disrupting pathophysiological activity. In AD, it may be more advantageous to use stimulation to reinforce or rebuild oscillatory activities that are disrupted by the disease process. A primary candidate for such a target is the hippocampal theta oscillation, which provides a temporal framework for mnemonic processing and is altered in rodent models of AD. MATERIAL AND METHODS: We applied closed-loop electrical stimulation to the fornix of rats traversing a linear track, triggered by different phases of the ongoing theta oscillation in the hippocampal local field potential (LFP) using the OscillTrack algorithm. RESULTS: Stimulation at different target phases could robustly suppress or amplify the theta oscillation, and these effects were significantly larger than those caused by open-loop replay of the same stimulation pattern. Amplification of the theta oscillation could be achieved irrespective of the locomotor speed of the animal, showing that it did not result from a secondary effect of behavioural change. CONCLUSIONS: Our findings demonstrate that closed-loop fx-DBS is a viable method of modulating the amplitude of hippocampal theta oscillations that could be applied in human devices to provide a constructive intervention with the potential to boost memory circuit function in AD.
High-throughput screen of 100 000 small molecules in C9ORF72 ALS neurons identifies spliceosome modulators that mobilize G4C2 repeat RNA into nuclear export and repeat associated non-canonical translation.
An intronic G4C2 repeat expansion in the C9ORF72 gene is the major known cause for Amyotrophic Lateral Sclerosis (ALS), with current evidence for both, loss of function and pathological gain of function disease mechanisms. We screened 96 200 small molecules in C9ORF72 patient iPS neurons for modulation of nuclear G4C2 RNA foci and identified 82 validated hits, including the Brd4 inhibitor JQ1 as well as novel analogs of Spliceostatin-A, a known modulator of SF3B1, the branch point binding protein of the U2-snRNP. Spliceosome modulation by these SF3B1 targeted compounds recruits SRSF1 to nuclear G4C2 RNA, mobilizing it from RNA foci into nucleocytoplasmic export. This leads to increased repeat-associated non-canonical (RAN) translation and ultimately, enhanced cell toxicity. Our data (i) provide a new pharmacological entry point with novel as well as known, publicly available tool compounds for dissection of C9ORF72 pathobiology in C9ORF72 ALS models, (ii) allowing to differentially modulate RNA foci versus RAN translation, and (iii) suggest that therapeutic RNA foci elimination strategies warrant caution due to a potential storage function, counteracting translation into toxic dipeptide repeat polyproteins. Instead, our data support modulation of nuclear export via SRSF1 or SR protein kinases as possible targets for future pharmacological drug discovery.
Contributed Talks I: Information integration in early visual processing revealed by Vernier thresholds.
Vernier acuity thresholds represent minimal detectable spatial offset between two closely placed targets. We previously showed that Vernier thresholds for a Poisson-limited ideal observer with access to the cone excitations are determined jointly by duration and contrast through the quantity duration x contrast squared. Here we measured thresholds in 7 human observers for combinations of stimulus contrast (100%, 50%, 25%, and 12.5%) and duration (16.7 ms, 66.7 ms, 266.7 ms and 1066.7 ms), while fixing other stimulus properties (foveal viewing; two achromatic vertical bars; length 10.98 arcmin; width 4.39 arcmin; vertical gap 0.878 arcmin). The combinations of duration and contrast were chosen to form four groups of constant duration x contrast squared. Thresholds were a decreasing function of duration x contrast squared. A one-way between observers ANOVA does not reject the hypothesis threshold duration and contrast are integrated through the quantity duration x contrast squared, but the residuals obtained by predicting threshold within each of the four groups by its mean varied systematically with duration, indicating that duration x contrast squared does not fully summarize the information integration. This difference between ideal and human performance indicates that post-receptoral factors not included in the ideal observer model, such as temporal filtering, affect human performance. These factors will be included in future modeling.
Contributed Talks I: Fixational eye movements and retinal adaptation: optimizing drift to maximize information acquisition.
Fixational eye movements (FEMs) are small, fluctuating eye motions when fixating on a target. Given our visual system is evolved, we may ask why FEMs are beneficial and whether they are optimal. A possible reason for FEMs is overcoming retinal adaptation (fading perception of a fixed image). We present a simple model system allowing theoretical investigation of FEM influence on information about an external stimulus. The model incorporates temporal stimulus modulation, retinal image motion due to the drift component of FEMs, blurring due to optics and receptor size, uniform sampling by the receptor array, adaptation via a bandpass temporal filter, and added noise. We investigate how elements of the model mediate the information transmitted, via: i) mutual information between visual system response and external stimulus, ii) direct estimation of stimulus from the system response, and iii) contrast threshold for signal detection. For all these we find a common quantity that must be maximized. For each spatial frequency this quantity is a summed power transmitted due to stimulus temporal modulation and phase shifts from FEMs, when passed through the temporal filter. We demonstrate that the information transmitted can be increased by adding local persistence to an underlying diffusive process. We also quantify the contribution of FEMs to signal detection for targets of different size and duration; such predictions provide a qualitative account of human psychophysical performance.