Biology subjects

Scholl, J.

Publications and source records attributed to Scholl, J..

6 recordsLinked to original sources

bioRxiv2024

Controllability and cause in human collaboration

There has been considerable interest in how we ascertain whether an environment is controllable and the neural mechanisms mediating this process. An especially acute version of this problem occurs when multiple people collaborate towards a joint outcome. Here we demonstrate that in such ambiguous social contexts, people engage in specific patterns of behaviour that we refer to as active disambiguation. This process helps individuals establish what they themselves, as opposed to others, control and what consequence they themselves cause or that another person causes. People identify when active disambiguation is needed and engage in it at that time. A pattern of activity in the supramarginal gyrus that emerges during and after active disambiguation is linked to establishing controllability and tracking the outcomes from which control is inferred. Activity in this brain region also signals a second learning mechanism, by which individuals attribute outcomes to themselves versus others, in proportion to their perceived control.

neuroscience↗

bioRxiv2023

An ancient subcortical circuit decides when to orient to threat in humans

Many psychiatric symptoms have been linked to threat-related perception and learning processes. In addition, however, there may also be mechanisms for balancing effectively between threat- and reward-related behaviors and these may also vary between individuals. We investigated neural activity associated with spontaneous switching between foraging for rewards and vigilance for threats with 7T fMRI. In a virtual naturalistic environment, participants freely switched between the two modes of behavior. Switching was driven by estimates of likelihood of threat and reward. Both tracking of threat and switching to vigilance were associated with specific but distributed patterns of activity spanning habenula, dorsal raphe nucleus (DRN), anterior cingulate cortex, and anterior insula cortex. Distinct distributed patterns heralded returns to reward-oriented behavior. Individual variation in DRN activity reflected individual variation in vigilance. All activity patterns were replicated in an initially held-out portion of data.

neuroscience↗

bioRxiv2020

Maximizing PHB content in Synechocystis sp. PCC 6803: development of a new photosynthetic overproduction strain.

PHB (poly-hydroxy-butyrate) represents a promising bioplastic variety with good biodegradation properties. Furthermore, PHB can be produced completely carbon-neutral when synthesized in the natural producer cyanobacterium Synechocystis sp. PCC 6803. This model strain has a long history of various attempts to further boost its low amounts of produced intracellular PHB of ~15 % per cell-dry-weight (CDW). We have created a new strain that lacks the regulatory protein PirC (gene product of sll0944), which causes a rapid conversion of the intracellular glycogen pools to PHB under nutrient limiting conditions. To further improve the intracellular PHB content, two genes from the PHB metabolism, phaA and phaB from the known production strain Cupriavidus necator, were introduced under the regime of the strong promotor PpsbA2. The created strain, termed PPT1 ({Delta}sll0944-REphaAB), produced high amounts of PHB under continuous light as well under day-night rhythm. When grown in nitrogen and phosphor depleted medium, the cells produced up to 63 % / CDW. Upon the addition of acetate, the content was further increased to 81 % / CDW. The produced polymer consists of pure PHB, which is highly isotactic. The achieved amounts were the highest ever reported in any known cyanobacterium and demonstrate the potential of cyanobacteria for a sustainable, industrial production of PHB.

microbiology↗

bioRxiv2020

The Novel PII-Interacting Regulator PirC (Sll0944) Identifies 3-Phosphoglycerate Mutase (PGAM) as Central Control Point of Carbon Storage Metabolism in Cyanobacteria

Nitrogen limitation imposes a major transition in the life-style of non-diazotrophic cyanobacteria, which is regulated via a complex interplay of regulatory factors, involving, the nitrogen-specific transcription factor NtcA and the pervasive signal processor PII. Immediately upon nitrogen-limitation, newly fixed carbon is re-directed towards glycogen synthesis. How the metabolic switch for distributing fixed carbon to either glycogen or cellular building blocks is operated was poorly understood. Here we identify from Synechocystis sp. PCC 6803 a novel PII interactor, PirC, (Sll0944) that controls 3-phosphoglycerate mutase (PGAM), the enzyme that deviates newly fixed CO2 towards lower glycolysis. PirC acts as competitive inhibitor of PGAM and this interaction is tuned by PII/2-oxoglutarate. High oxoglutarate release PirC from PII-complex to inhibit PGAM. Accordingly, PirC deficient mutant, as compared to the wild-type, shows strongly reduced glycogen levels upon nitrogen deprivation whereas polyhydroxybutyrate granules are over-accumulated. Metabolome analysis revealed an imbalance in 3-phosphoglycerate to pyruvate levels in the PirC mutant, conforming that PirC controls the carbon flux in cyanobacteria via mutually exclusive interaction with either PII or PGAM.

microbiology↗

bioRxiv2018

Motor learning shapes temporal activity in human sensorimotor cortex

Although neuroimaging techniques have provided vital insights into the anatomical regions involved in motor learning, the underlying changes in temporal dynamics are not well understood. Using magnetoencephalography and Hidden Markov Modelling to model the dynamics of neural oscillations on data-adaptive time-scales, we detected specific changes in movement-related sensorimotor {beta}-activity during practice of a self-paced sequential visuo-motor task. The behaviourally-relevant neural signature generalised to another motor task, emphasising the centrality of {beta}-activity in motor plasticity.

neuroscience↗

bioRxiv2017

Simultaneous representation of a spectrum of dynamically changing value estimates during decision making

Decisions are based on value expectations derived from experience. We show that dorsal anterior cingulate cortex and three other brain regions hold multiple representations of choice value based on different time-scales of experience organized in terms of systematic gradients across the cortex. Some parts of each area represent value estimates based on recent reward experience while others represent value estimates based on experience over the longer term. The value estimates within these four brain areas interact with one another according to their temporal scaling. Some aspects of the representations change dynamically as the environment changes. The spectrum of value estimates may act as a flexible selection mechanism for combining experience-derived value information with other aspects of value to allow flexible and adaptive decisions in changing environments.

neuroscience↗