Emergence of synaptic organization and computation in dendrites

Single neurons in the brain exhibit astounding computational capabilities, which gradually emerge throughout development and enable them to become integrated into complex neural circuits. These capabilities derive in part from the precise arrangement of synaptic inputs on the neurons’ dendrites. While the full computational benefits of this arrangement are still unknown, a picture emerges in which synapses organize according to their functional properties across multiple spatial scales. In particular, on the local scale (tens of microns), excitatory synaptic inputs tend to form clusters according to their functional similarity, whereas on the scale of individual dendrites or the entire tree, synaptic inputs exhibit dendritic maps where excitatory synapse function varies smoothly with location on the tree. The development of this organization is supported by inhibitory synapses, which are carefully interleaved with excitatory synapses and can flexibly modulate activity and plasticity of excitatory synapses. Here, we summarize recent experimental and theoretical research on the developmental emergence of this synaptic organization and its impact on neural computations.

Epigenetic function in neurodevelopment and cognitive impairment

Brain development comprises a fine-tuned ensemble of molecular processes that need to be orchestrated in a very coordinated way throughout time and space. A wide array of epigenetic mechanisms, ranging from DNA methylation and histone modifications to noncoding RNAs, have been identified for their major role in guiding developmental processes such as progenitor proliferation, neuronal migration, and differentiation through precise regulation of gene expression programs. The importance of epigenetic processes during development is reflected by the high prevalence of neurodevelopmental diseases which are caused by a lack or mutation of genes encoding for transcription factors and other epigenetic regulators. Most of these factors process central functions for proper brain development, and respective mutations lead to severe cognitive defects. A better understanding of epigenetic programs during development might open new routes toward better treatment options for related diseases.

Neurobiology of phenotypic plasticity in the light of climate change

Phenotypic plasticity describes the ability of an organism with a given genotype to respond to changing environmental conditions through the adaptation of the phenotype. Phenotypic plasticity is a widespread means of adaptation, allowing organisms to optimize fitness levels in changing environments. A core prerequisite for adaptive predictive plasticity is the existence of reliable cues, i.e. accurate environmental information about future selection on the expressed plastic phenotype. Furthermore, organisms need the capacity to detect and interpret such cues, relying on specific sensory signalling and neuronal cascades. Subsequent neurohormonal changes lead to the transformation of phenotype A into phenotype B. Each of these activities is critical for survival. Consequently, anything that could impair an animal’s ability to perceive important chemical information could have significant ecological ramifications. Climate change and other human stressors can act on individual or all of the components of this signalling cascade. In consequence, organisms could lose their adaptive potential, or in the worst case, even become maladapted. Therefore, it is key to understand the sensory systems, the neurobiology and the physiological adaptations that mediate organisms’ interactions with their environment. It is, thus, pivotal to predict the ecosystem-wide effects of global human forcing. This review summarizes current insights on how climate change affects phenotypic plasticity, focussing on how associated stressors change the signalling agents, the sensory systems, receptor responses and neuronal signalling cascades, thereby, impairing phenotypic adaptations.

What the eye tells the brain: retinal feature extraction

To provide a compact and efficient input to the brain, sensory systems separate the incoming information into parallel feature channels. In the visual system, parallel processing starts in the retina. Here, the image is decomposed into multiple retinal output channels, each selective for a specific set of visual features like motion, contrast, or edges. In this article, we will summarize recent findings on the functional organization of the retinal output, the neural mechanisms underlying its diversity, and how single visual features, like color, are extracted by the retinal network. Unraveling how the retina – as the first stage of the visual system – filters the visual input is an important step toward understanding how visual information processing guides behavior.

Brain–body communication in stroke

Stroke is a leading cause of death and disability worldwide with limited therapeutic options available for selected groups of patients. The susceptibility to stroke depends also on systemic parameters, and some stroke risk factors are modifiable, such as atrial fibrillation (AF) or hypertension. When considering new treatment strategies, it is important to remember that the consequences of stroke are not limited to the central nervous system (CNS) injury, but reach beyond the boundaries of the brain. We provide here a brief overview of the mechanisms of how the brain communicates with the body, focusing on the heart, immune system, and gut microbiota (GM).

Recent developments and future perspectives on neuroelectronic devices

Neuroscientific discoveries and the development of recording and stimulation tools are deeply connected. Over the past decades, the progress in seamlessly integrating such tools in the form of neuroelectronic devices has been tremendous. Here, we review recent advances and key aspects of this goal. Firstly, we illustrate improvements with respect to the coupling between cells/tissue and recording/stimulation electrodes. Thereafter, we cover attempts to mitigate the foreign body response by reducing the devices’ invasiveness. We follow up with a description of specialized electronic hardware aimed at the needs of bioelectronic applications. Lastly, we outline how additional modalities such as optical techniques or ultrasound could in the future be integrated into neuroelectronic implants.

Environmental exposures impact the nervous system in a life stage-specific manner

Exposure to environmental pollutants like chemicals or air pollution is major health concern for the human population. Especially the nervous system is a sensitive target for environmental toxins with exposures leading to life stage-dependent neurotoxicity. Developmental and adult neurotoxicity are characterized by specific adverse outcomes ranging from neurodevelopmental disorders to neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. The risk assessment process for human health protection is currently undergoing a paradigm change toward new approach methods that allow mechanism-based toxicity assessment. As a flagship project, an in vitro battery of test methods for developmental neurotoxicity evaluation is currently supported by the Organization for Economic Co-operation and Development (OECD). A plethora of stem cell-based methods including brain spheres and organoids are currently further developed to achieve time- and cost-saving tools for linking MoA-based hazards to adverse health effects observed in humans.