View by multiple tags thebrain10/2/2023 ![]() Human cerebral organoids derived from embryonic or induced pluripotent stem cells are unique in their ability to recapitulate early events of embryonic brain development ( Lancaster et al., 2013). Our label-free imaging system constitutes a particularly useful platform for tracking normal and abnormal development in individual organoids, as well as for screening therapeutic molecules via intact organoid imaging. Long-term imaging live organoids reveals that shorter migration distances and slower migration speeds of mutant radially migrating neurons are associated with more tortuous trajectories. Optimizing a custom-made three-photon microscope to image intact cerebral organoids generated from Rett Syndrome patients, we show defects in the ventricular zone volumetric structure of mutant organoids compared to isogenic control organoids. Here, we demonstrate label-free three-photon imaging of whole, uncleared intact organoids (~2 mm depth) to assess early events of early human brain development. Analyses of cerebral organoids thus far have been performed in sectioned tissue or in superficial layers due to their high scattering properties. Read the original article in The Atlantic.Human cerebral organoids are unique in their development of progenitor-rich zones akin to ventricular zones from which neuronal progenitors differentiate and migrate radially. It is an enlarged intimate supplement to his memory. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It needs a name, and, to coin one at random, "memex" will do. One cannot hope thus to equal the speed and flexibility with which the mind follows an associative trail, but it should be possible to beat the mind decisively in regard to the permanence and clarity of the items resurrected from storage.Ĭonsider a future device for individual use, which is a sort of mechanized private file and library. Selection by association, rather than indexing, may yet be mechanized. ![]() The first idea, however, to be drawn from the analogy concerns selection. ![]() In minor ways he may even improve, for his records have relative permanency. Man cannot hope fully to duplicate this mental process artificially, but he certainly ought to be able to learn from it. Yet the speed of action, the intricacy of trails, the detail of mental pictures, is awe-inspiring beyond all else in nature. It has other characteristics, of course trails that are not frequently followed are prone to fade, items are not fully permanent, memory is transitory. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain. Having found one item, moreover, one has to emerge from the system and re-enter on a new path. It can be in only one place, unless duplicates are used one has to have rules as to which path will locate it, and the rules are cumbersome. ![]() When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found (when it is) by tracing it down from subclass to subclass. Our ineptitude in getting at the record is largely caused by the artificiality of systems of indexing. The real heart of the matter of selection, however, goes deeper than a lag in the adoption of mechanisms by libraries, or a lack of development of devices for their use.
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