Lifeboat Foundation

Human brain organoids are an intrinsically self-organized neuronal ensemble grown from three-dimensional assemblies of human-iPSCs. As shown here, brain organoids offer a window into the complex neuronal activity that emerges from intrinsically-formed circuits capable of mirroring aspects of the developing human brain³². Applying high-density CMOS MEA to large multi-cellular networks spanning millimeters of the brain organoid cross-sections we isolated single-unit activity and computed the timing of successive action potentials not due to refractoriness referred to as ISIs. As observed in neocortical neurons in vivo, we observed action potentials with irregular ISI’s that followed a Poisson-like process. From a set of 224 neurons analyzed from four different organoids, 16% ± 8% of the total units fit a Poisson distribution (Fig. 3) with, by definition, the CV approaches one for a perfectly homogenous Poisson process, whereas purely periodic distributions have CV values of zero. Thus, a minority fraction of ISIs were highly irregular (Fig. 3), whereas a majority displayed comparatively more regular spiking patterns with less variation (denoted by a lower CV), which may function to send lower-noise spike-rate signals. ISI distributions have also been fitted to gamma distributions that are mathematically equivalent to an exponential distribution when the shape parameter (k) is one and converges to a normal distribution for large k, thus providing a useful measure of ISI-regularity similar to the CV²⁸. Depending on architectonically defined brain regions with specialized cellular compositions and intrinsic circuitry, neurons process information differently^67,68,69. Indeed, neuronal firing varies considerably across cortical regions of monkeys^28,70,71. Therefore, different organizational features across the brain organoid may exhibit different dynamics to account for the observed ISI distributions. The minority fraction of irregular ISI distributions may be a feature of higher levels of entropy and circuit complexity and contain increased capacity for computation and information transfer as found in prefrontal cortex compared to more regular firing patters found in motor regions²⁸.

We derived a graph of weighted edges that couple single unit node pairs to send and receive spikes over a wide spatial range. Due to the thickness of our organoid slices, many neurons in the slice are too far from any electrode for their spikes to be detected⁵³. Thus, we cannot rule out the possibility that intermediate undetected neurons may account for the coupling between two correlated units. The graph does not imply downstream or upstream routes of information transfer beyond the individual binary couplings. Importantly, what the network does demonstrate is a non-random pattern of a relatively small number of statistically strong (reliable) couplings against a backdrop of weaker couplings. As demonstrated in the murine brain^51,52, high anatomical connection strength edges shape a non-random framework against a background of weaker ones (Fig. 6 and Supplementary Fig. 14). The majority of the singe units (nodes), which we refer to as brokers, have large proportions of incoming and outgoing edges. The dynamic balance among receivers and senders could likely reflect short-term plasticity⁷².

Brain organoids—composed of roughly one million cells—have neuronal assemblies of sufficient size, cellular orientation, connectivity and co-activation capable of generating field potentials in the extracellular space from their collective transmembrane currents. The basis for low frequency LFPs may be the cellular diversity that emerges in the organoid from the variety of GABAergic cells (Fig. 2), consistent with their role in the generation of highly correlated activity networks detected as LFPs³¹, parvalbumin cells (Fig. 2c), associated with sustaining network dynamics⁷³, and axon tracts that extended over millimeters (Fig. 2b). Coherence of theta oscillations over spatial extents of the organoid was observed and was unlikely due to volume conduction from distant sources, as happens in EEG and MEG measurements⁵⁴, because the voltage recordings were conducted within a small tissue volume (≈3.5 mm³). Consistent with minimal volume conduction effects, we validated theta oscillations by demonstrating that the imaginary part of coherency⁵⁴ projected onto the same spatial locations identified by cross-correlation analysis (Supplementary Fig. 19). Correlations between theta oscillations and local neuronal firing (Fig. 7) strongly supported a local source for the rhythmic activity^19,20,53. The local volume through which theta dispersed extended to the z-dimension as shown with the Neuropixels shank (Fig. 9).

Here we show that DS2 is an online, synchronous population event accompanied by widespread increases in neural activity and brief arousalions. On the basis of the stationary activation of place cells with fields close to the mouse’s current location, we propose that DS2 may serve as a mechanism to regularly ground the hippocampal representation of position in an environment during immobility. Rapidly switching between current (DS2) and remote (SPW-R) locations would enable cognitive flexibility that varies with sudden changes in the animal’s internal state or changes in the environment (for example, a startling noise). Synchronous neural activity during DS2 may provide opportunity windows for synaptic plasticity, consistent with our findings linking DS2 to associative memory formation.

At the microcircuit level, distinct brain states are shaped by the non-uniform recruitment of local inhibitory cells, which are key for directing information flow²⁷. As arousal-activated AACs heterogeneously innervate principal cells^19,20 and are highly active during DS2 but mostly silent during SPW-Rs, this GABAergic cell (and probably others, such as TORO cells) may be important in regulating the distinct ensemble activity between DS2 and SPW-Rs. At a network level, DS2 is thought to be primarily triggered by the medial entorhinal cortex, which contains neurons that encode self-referenced movement variables, locations and environmental borders^28,29,30. This self-referenced spatial input may indeed be key for recruiting spatially tuned hippocampal cells corresponding to an animal’s current position during DS2. Both tones and air puffs reliably evoked DS2 and promoted current position encoding, but the identity of the stimulus (tone versus puff) could not be reliably decoded.

In the past 10 years, gene-editing and organoid culture have completely changed the process of biology. Congenital nervous system malformations are difficult to study due to their polygenic pathogenicity, the complexity of cellular and neural regions of the brain, and the dysregulation of specific neurodevelopmental processes in humans. Therefore, the combined application of CRISPR-Cas9 in organoid models may provide a technical platform for studying organ development and congenital diseases. Here, we first summarize the occurrence of congenital neurological malformations and discuss the different modeling methods of congenital nervous system malformations. After that, it focuses on using organoid to model congenital nervous system malformations. Then we summarized the application of CRISPR-Cas9 in the organoid platform to study the pathogenesis and treatment strategies of congenital nervous system malformations and finally looked forward to the future.

Keywords: organoid, CRISPR-Cas9, congenital nervous system malformation, central nervous system, 3D

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Brain organoids have become increasingly used systems allowing 3D-modeling of human brain development, evolution, and disease. To be able to make full use of these modeling systems, researchers have developed a growing toolkit of genetic modification techniques. These techniques can be applied to mature brain organoids or to the preceding embryoid bodies (EBs) and founding cells. This review will describe techniques used for transient and stable genetic modification of brain organoids and discuss their current use and respective advantages and disadvantages. Transient approaches include adeno-associated virus (AAV) and electroporation-based techniques, whereas stable genetic modification approaches make use of lentivirus (including viral stamping), transposon and CRISPR/Cas9 systems. Finally, an outlook as to likely future developments and applications regarding genetic modifications of brain organoids will be presented.

The development of brain organoids (Kadoshima et al., 2013; Lancaster et al., 2013) has opened up new ways to study brain development and evolution as well as neurodevelopmental disorders. Brain organoids are multicellular 3D structures that mimic certain aspects of the cytoarchitecture and cell-type composition of certain brain regions over a particular developmental time window (Heide et al., 2018). These structures are generated by differentiation of induced pluripotent stem cells (iPSCs) or embryonic stem cells (ESCs) into embryoid bodies followed by, or combined, with neural induction (Kadoshima et al., 2013; Lancaster et al., 2013). In principle, two different classes of brain organoid protocols can be distinguished, namely: (i) the self-patterning protocols which produce whole-brain organoids; and (ii) the pre-patterning protocols which produce brain region-specific organoids (Heide et al., 2018).

It is with sadness — and deep appreciation of my friend and colleague — that I must report the passing of Vernor Vinge.

The technological singularity —or simply the singularity^[1] —is a hypothetical future point in time at which technological growth becomes uncontrollable and irreversible, resulting in unforeseeable consequences for human civilization.^[2][3] According to the most popular version of the singularity hypothesis, I. J. Good’s intelligence explosion model, an upgradable intelligent agent will eventually enter a “runaway reaction” of self-improvement cycles, each new and more intelligent generation appearing more and more rapidly, causing an “explosion” in intelligence and resulting in a powerful superintelligence that qualitatively far surpasses all human intelligence.^[4]

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The good news is that a new company has developed an AI inner monologue, the bad news is this makes it significantly smarter.

Advances in oil and gas drilling have cut costs for a form of clean power that could help replace fossil fuels, according to the Department of Energy.

Now the agency is going all in on geothermal energy, which uses heat from deep within the Earth to produce largely pollution-free electricity.

“Gigantic aluminum spiders” might sound like the stuff of nightmares or an antagonist in an anime series. However, for one Norwegian company, they could be the future of the wind energy industry.

WindSpider, a tech company that focuses on onshore and offshore wind turbines, has developed a new self-erecting crane system that could revolutionize the way turbines are built.

Continue reading “Company develops revolutionary technology that allows wind turbines to practically build themselves: ‘It will be a gamechanger’” »

The first patient of Elon Musk’s Neuralink has been presented to the public. Noland Arbaugh had all but given up playing Civilization VI ever since a diving accident dislocated two vertebrae in his cervical spinal cord, leaving him paralyzed from the shoulders down.

When confined to his wheel chair, the 29-year-old American is totally dependent on the care of his parents, who need to shift his weight ever few hours to avoid pressure sores from sitting too long in the same position.

Moving a cursor on a display furthermore required the use of a mouth stick, a specialized assistive device used by quadriplegics.