Cholinergic interneurons have emerged as one of the key players controlling network functions in the striatum. Extracellularly recorded cholinergic interneurons acquire characteristic responses to ...sensory stimuli during reward-related learning, including a pause and subsequent rebound in spiking. However, the precise underlying cellular mechanisms have remained elusive. Here, we review recent advances in our understanding of the regulation of cholinergic interneuron activity. We discuss evidence of mechanisms that have been proposed to underlie sensory responses, including antagonistic actions by dopamine, recurrent inhibition via local interneurons, and an intrinsically generated membrane hyperpolarization in response to excitatory inputs. The review highlights outstanding questions and concludes with a model of the sensory responses and their downstream effects through dynamic acetylcholine receptor activation.
What does it mean to say we live in a permanent state of emergency? What are the juridical, political and social underpinnings of that framing? Has international law played a role in producing or ...challenging the paradigm of normalised emergency? How should we understand the relationship between imperialism, race and emergency legal regimes? In addressing such questions, this book situates emergency doctrine in historical context. It illustrates some of the particular colonial lineages that have shaped the state of emergency, and emphasises that contemporary formations of emergency governance are often better understood not as new or exceptional, but as part of an ongoing historical constellation of racialised emergency politics. The book highlights the connections between emergency law and violence, and encourages alternative approaches to security discourse. It will appeal to scholars and students of international law, colonial history, postcolonialism and human rights, as well as policymakers and social justice advocates.
Dopamine-dependent long-term plasticity is believed to be a cellular mechanism underlying reinforcement learning. In response to reward and reward-predicting cues, phasic dopamine activity ...potentiates the efficacy of corticostriatal synapses on spiny projection neurons (SPNs). Since phasic dopamine activity also encodes other behavioural variables, it is unclear how postsynaptic neurons identify which dopamine event is to induce long-term plasticity. Additionally, it is unknown how phasic dopamine released from arborised axons can potentiate targeted striatal synapses through volume transmission. To examine these questions we manipulated striatal cholinergic interneurons (ChIs) and dopamine neurons independently in two distinct in vivo paradigms. We report that long-term potentiation (LTP) at corticostriatal synapses with SPNs is dependent on the coincidence of pauses in ChIs and phasic dopamine activation, critically accompanied by SPN depolarisation. Thus, the ChI pause defines the time window for phasic dopamine to induce plasticity, while depolarisation of SPNs constrains the synapses eligible for plasticity.
Ionic polymers in action: Conjugated polyelectrolytes are an emerging class of multifunctional polymers that feature π-conjugated backbones festooned with ionic solubilizing groups. These materials ...have been exploited in a number of applications, including fluorescent biosensors, polymer light-emitting diodes, and polymer solar cells. MV²⁺=methylviologenOrganic optoelectronic polymers have evolved to the point where fine structural control of the conjugated main chain, coupled with solubilizing and property-modifying pendant substituents, provides an entirely new class of materials. Conjugated polyelectrolytes (CPEs) provide a unique set of properties, including water solubility and processability, main-chain-controlled exciton and charge transport, variable band gap light absorption and fluorescence, ionic interactions, and aggregation phenomena. These characteristics allow these materials to be considered for use in applications ranging from light-emitting diodes and electrochromic color-changing displays, to photovoltaic devices and photodetectors, along with chemical and biological sensors. This Review describes the evolution of CPE structures from simple polymers to complex materials, describes numerous photophysical aspects, including amplified quenching in macromolecules and aggregates, and illustrates how the physical and electronic properties lead to useful applications in devices.
Highlights • The acute effect of LI-rMS on layer 5 pyramidal neurons was investigated in vitro. • LI-rMS does not alter passive membrane properties. • LI-rMS induced hyperpolarized action potential ...thresholds. • LI-rMS Increased evoked spike firing frequency.
Plasticity at synapses between the cortex and striatum is considered critical for learning novel actions. However, investigations of spike-timing-dependent plasticity (STDP) at these synapses have ...been performed largely in brain slice preparations, without consideration of physiological reinforcement signals. This has led to conflicting findings, and hampered the ability to relate neural plasticity to behavior. Using intracellular striatal recordings in intact rats, we show here that pairing presynaptic and postsynaptic activity induces robust Hebbian bidirectional plasticity, dependent on dopamine and adenosine signaling. Such plasticity, however, requires the arrival of a reward-conditioned sensory reinforcement signal within 2 s of the STDP pairing, thus revealing a timing-dependent eligibility trace on which reinforcement operates. These observations are validated with both computational modeling and behavioral testing. Our results indicate that Hebbian corticostriatal plasticity can be induced by classical reinforcement learning mechanisms, and might be central to the acquisition of novel actions.Spike timing dependent plasticity (STDP) has been studied extensively in slices but whether such pairings can induce plasticity in vivo is not known. Here the authors report an experimental paradigm that achieves bidirectional corticostriatal STDP in vivo through modulation by behaviourally relevant reinforcement signals, mediated by dopamine and adenosine signaling.
Attention is critical to perception, serving to select behaviorally relevant information for privileged processing. To understand the neural mechanisms of attention, we must discern how attentional ...modulation varies by cell type and across cortical layers. Here, we test whether attention acts non-selectively across cortical layers or whether it engages the laminar circuit in specific and selective ways. We find layer- and cell-class-specific differences in several different forms of attentional modulation in area V4. Broad-spiking neurons in the superficial layers exhibit attention-mediated increases in firing rate and decreases in variability. Spike count correlations are highest in the input layer and attention serves to reduce these correlations. Superficial and input layer neurons exhibit attention-dependent decreases in low-frequency (<10 Hz) coherence, but deep layer neurons exhibit increases in coherence in the beta and gamma frequency ranges. Our study provides a template for attention-mediated laminar information processing that might be applicable across sensory modalities.
•Attention engages the V4 laminar circuit in selective ways•Superficial broad-spiking cells show increased rate and reliability with attention•Low-frequency coherence decreases with attention in superficial and input layers•Correlations in V4 are highest in the input layer
Attention is a critical component of perception. Here, Nandy et al. examine the laminar organization of attentional modulation in sensory cortex. They find layer- and cell-class-specific differences in the laminar cortical circuit in area V4.
Solution-processable electrochromic (EC) polymers that can be switched from one distinct color state to a highly transmissive and near colorless state are required for applications in both EC windows ...and displays. Using a tour around the color wheel, we describe the various EC polymer (ECP) compositions that now make a full palette of colors available demonstrating a set of structure−property relationships. Electrochemical and electrochromic characterization methodologies are described and their application to ECPs demonstrated. Processing and patterning methods including spray casting, screen-, flexo-, and ink jet printing, along with photo- and soft lithography are described. Absorptive/transmissive (window type) and absorptive/reflective (display type) devices are described as platforms for practical applications.
An essential aim of biomedical research is to translate basic science information obtained from preclinical research using small and large animal models into clinical practice for the benefit of ...humans. Research on rodent models has enhanced our understanding of complex pathophysiology, thus providing potential translational pathways. However, the success of translating drugs from pre-clinical to clinical therapy has been poor, partly due to the choice of experimental model. The sheep model, in particular, is being increasingly applied to the field of biomedical research and is arguably one of the most influential models of human organ systems. It has provided essential tools and insights into cardiovascular disorder, orthopaedic examination, reproduction, gene therapy, and new insights into neurodegenerative research. Unlike the widely adopted rodent model, the use of the sheep model has an advantage over improving neuroscientific translation, in particular due to its large body size, gyrencephalic brain, long lifespan, more extended gestation period, and similarities in neuroanatomical structures to humans. This review aims to summarise the current status of sheep to model various human diseases and enable researchers to make informed decisions when considering sheep as a human biomedical model.
PDF
