Living cells are bombarded with many kinds of incoming molecular signal that influence their behavior. Being able to measure those signals and how cells respond to them through downstream molecular signaling networks could help scientists learn much more about how cells work, including what happens as they age or become diseased.

Right now, this kind of comprehensive study is not possible because current techniques for imaging cells are limited to just a handful of different molecule types within a cell at one time. However, MIT researchers have developed an alternative method that allows them to observe up to seven different molecules at a time, and potentially even more than that.

“There are many examples in biology where an event triggers a long downstream cascade of events, which then causes a specific cellular function,” says Edward Boyden, the Y. Eva Tan Professor in Neurotechnology. “How does that occur? It’s arguably one of the fundamental problems of biology, and so we wondered, could you simply watch it happen?”

A new ingestible capsule can monitor vital signs from within the patient’s GI tract. The sensor could be used for less intrusive monitoring of sleep disorders such as sleep apnea, or for detecting opioid overdoses.

Diagnosing sleep disorders such as sleep apnea usually requires a patient to spend the night in a sleep lab, hooked up to a variety of sensors and monitors. Researchers from MIT, Celero Systems, and West Virginia University hope to make that process less intrusive, using an ingestible capsule they developed that can monitor vital signs from within the patient’s GI tract.

The capsule, which is about the size of a multivitamin, uses an accelerometer to measure the patient’s breathing rate and heart rate. In addition to diagnosing sleep apnea, the device could also be useful for detecting opioid overdoses in people at high risk, the researchers say.

Activity of neurons embedded in networks is an inseparable composition of evoked and intrinsic processes. Prevalence of either component depends on the neuron’s function and state (e.g. low/high conductance or depolarization states). Dominant intrinsic firing is thought functionally normal for the pacemaker neuron, but not for the sensory afferent neuron or spinal motoneuron serving to transmit rather than to originate signals. Activity of the multi-functional networked cell, depending on its intrinsic states, bears both cell-and network-defined features. Complex firing patterns of a neuron are conventionally attributed to complex spatial-temporal organization of inputs received from the network-mates via synapses, in vast majority dendritic. This attribution reflects widespread views of the within-cell job sharing, such that the main function of the dendrites is to receive signals and deliver them to the axo-somatic trigger zone, which actually generates the output pattern. However, these views require revisiting with account of active properties of the dendrites due to voltage-dependent channels found in the dendritic membrane of practically all types of explored neurons. Like soma and axon, the dendrites with active membrane are able to generate self-maintained, propagating depolarizations and thus share intrinsic pattern-forming role with the trigger zone. Unlike the trigger zone, the dendrites have complex geometry, which is subject to developmental, activity-dependent, or neurodegenerative changes. Structural features of the arborization inevitably impact on electrical states and cooperative behavior of its constituting parts at different levels of organization, from branches and sub-trees to voltage-and ligand-gated ion channels populating the membrane. Nearly two decades of studies have brought numerous phenomenological demonstrations of influence of the dendritic structure on firing patterns in neurons. A necessary step forward is to comprehend these findings and build a firm theoretical basis, including quantitative relationships between geometrical and electrical characteristics determining intrinsic firing of neurons. This Research Topic is aimed at bringing together contributions of researches from different domains of expertise and building a conceptual framework for deeper insight into the nature of dynamic intrinsic motifs in the firing patterns.

We welcome research and methodology papers, mini-reviews, conceptual generalizations and opinions on the following issues:

1. Electrical states of heterogeneous populations of ion channels: definition, life-times, meta-and multi-stability.