scholarly journals Human brain organoids assemble functionally integrated bilateral optic vesicles

2021 ◽  
Author(s):  
Elke Gabriel ◽  
Walid Albanna ◽  
Giovanni Pasquini ◽  
Anand Ramani ◽  
Natasa Josipovic ◽  
...  
Keyword(s):  
Human Brain ◽  
Cortical Neurons ◽  
Neuronal Networks ◽  
Retinal Pigment ◽  
Optic Vesicle ◽  
Complex Process ◽  
Optic Vesicles ◽  
Sensory Structures ◽  
Cellular Components ◽  
Synapsin 1

During embryogenesis, optic vesicles develop from the diencephalon via a complex process of organogenesis. Using iPSC-derived human brain organoids, we attempted to simplify the complexities and demonstrate the formation of forebrain-associated bilateral optic vesicles, cellular diversity, and functionality. Around day thirty, brain organoids could assemble optic vesicles, which progressively develop as visible structures within sixty days. These optic vesicle-containing brain organoids (OVB-Organoids) constitute a developing optic vesicle's cellular components, including the primitive cornea and lens-like cells, developing photoreceptors, retinal pigment epithelia, axon-like projections, and electrically active neuronal networks. Besides, OVB-Organoids also display synapsin-1, CTIP-positive, myelinated cortical neurons, and microglia. Interestingly, various light intensities could trigger photoreceptor activity of OVB-Organoids, and light sensitivities could be reset after a transient photo bleach blinding. Thus, brain organoids have the intrinsic ability to self-organize forebrain-associated primitive sensory structures in a topographically restricted manner and can allow conducting interorgan interaction studies within a single organoid.

Music Neurotechnology for Sound Synthesis: Sound Synthesis with Spiking Neuronal Networks

Leonardo ◽  
2009 ◽  
Vol 42 (5) ◽  
pp. 439-442 ◽  
Author(s):  
Eduardo R. Miranda ◽  
John Matthias
Keyword(s):  
Cortical Neurons ◽  
Neuronal Networks ◽  
Research Area ◽  
Sound Synthesis ◽  
Ongoing Research ◽  
Computer Interfaces ◽  
Engineering Sciences ◽  
New Research ◽  
Sound Files

Music neurotechnology is a new research area emerging at the crossroads of neurobiology, engineering sciences and music. Examples of ongoing research into this new area include the development of brain-computer interfaces to control music systems and systems for automatic classification of sounds informed by the neurobiology of the human auditory apparatus. The authors introduce neurogranular sampling, a new sound synthesis technique based on spiking neuronal networks (SNN). They have implemented a neurogranular sampler using the SNN model developed by Izhikevich, which reproduces the spiking and bursting behavior of known types of cortical neurons. The neurogranular sampler works by taking short segments (or sound grains) from sound files and triggering them when any of the neurons fire.

Different roles for Pax6 in the optic vesicle and facial epithelium mediate early morphogenesis of the murine eye

Development ◽  
2000 ◽  
Vol 127 (5) ◽  
pp. 945-956 ◽  
Author(s):  
J.M. Collinson ◽  
R.E. Hill ◽  
J.D. West
Keyword(s):  
Histological Analysis ◽  
Eye Development ◽  
Wild Type Mouse ◽  
Lens Epithelium ◽  
Optic Vesicle ◽  
Wild Type ◽  
Adhesive Properties ◽  
Optic Vesicles ◽  
Lens Placode ◽  
Mutant Cells

Chimaeric mice were made by aggregating Pax6(−/−) and wild-type mouse embryos, in order to study the interaction between the optic vesicle and the prospective lens epithelium during early stages of eye development. Histological analysis of the distribution of homozygous mutant cells in the chimaeras showed that the cell-autonomous removal of Pax6(−/−) cells from the lens, shown previously at E12.5, is nearly complete by E9.5. Most mutant cells are eliminated from an area of facial epithelium wider than, but including, the developing lens placode. This result suggests a role for Pax6 in maintaining a region of the facial epithelium that has the tissue competence to undergo lens differentiation. Segregation of wild-type and Pax6(−/−) cells occurs in the optic vesicle at E9.5 and is most likely a result of different adhesive properties of wild-type and mutant cells. Also, proximo-distal specification of the optic vesicle (as assayed by the elimination of Pax6(−/−) cells distally), is disrupted in the presence of a high proportion of mutant cells. This suggests that Pax6 operates during the establishment of patterning along the proximo-distal axis of the vesicle. Examination of chimaeras with a high proportion of mutant cells showed that Pax6 is required in the optic vesicle for maintenance of contact with the overlying lens epithelium. This may explain why Pax6(−/−) optic vesicles are inefficient at inducing a lens placode. Contact is preferentially maintained when the lens epithelium is also wild-type. Together, these results demonstrate requirements for functional Pax6 in both the optic vesicle and surface epithelia in order to mediate the interactions between the two tissues during the earliest stages of eye development.

scholarly journals Taste quality representation in the human brain

2019 ◽  
Author(s):  
Jason A. Avery ◽  
Alexander G. Liu ◽  
John E. Ingeholm ◽  
Cameron D. Riddell ◽  
Stephen J. Gotts ◽  
...  
Keyword(s):  
Human Brain ◽  
Cortical Neurons ◽  
Brain Regions ◽  
Taste Quality ◽  
7 Tesla ◽  
Mammalian Brain ◽  
High Magnetic Field Strength ◽  
Magnetic Resonance Imaging Mri ◽  
Spatial Locations ◽  
Univariate Analyses

SUMMARYIn the mammalian brain, the insula is the primary cortical substrate involved in the perception of taste. Recent imaging studies in rodents have identified a gustotopic organization in the insula, whereby distinct insula regions are selectively responsive to one of the five basic tastes. However, numerous studies in monkeys have reported that gustatory cortical neurons are broadly-tuned to multiple tastes, and tastes are not represented in discrete spatial locations. Neuroimaging studies in humans have thus far been unable to discern between these two models, though this may be due to the relatively low spatial resolution employed in taste studies to date. In the present study, we examined the spatial representation of taste within the human brain using ultra-high resolution functional magnetic resonance imaging (MRI) at high magnetic field strength (7-Tesla). During scanning, participants tasted sweet, salty, sour and tasteless liquids, delivered via a custom-built MRI-compatible tastant-delivery system. Our univariate analyses revealed that all tastes (vs. tasteless) activated primary taste cortex within the bilateral dorsal mid-insula, but no brain region exhibited a consistent preference for any individual taste. However, our multivariate searchlight analyses were able to reliably decode the identity of distinct tastes within those mid-insula regions, as well as brain regions involved in affect and reward, such as the striatum, orbitofrontal cortex, and amygdala. These results suggest that taste quality is not represented topographically, but by a combinatorial spatial code, both within primary taste cortex as well as regions involved in processing the hedonic and aversive properties of taste.

scholarly journals Synaptic Signals from Glutamate-Treated Neurons Induce Aberrant Post-Synaptic Signals in Untreated Neuronal Networks

2020 ◽  
Vol 14 (1) ◽  
pp. 59-62
Author(s):  
Mary Guaraldi ◽  
Sangmook Lee ◽  
Thomas B. Shea
Keyword(s):  
Cortical Neurons ◽  
Neuronal Networks ◽  
Synaptic Function ◽  
Glutamate Excitotoxicity ◽  
Synaptic Connectivity ◽  
Extracellular Glutamate ◽  
Glutamate Neurotoxicity ◽  
Wide Range ◽  
Cortical Regions

Background and Objective: Glutamate neurotoxicity is associated with a wide range of disorders and can impair synaptic function. Failure to clear extracellular glutamate fosters additional cycles and spread of regional hyperexcitation. Methods and Results: Using cultured murine cortical neurons, herein it is demonstrated that synaptic signals generated by cultures undergoing glutamate-induced hyperactivity can invoke similar effects in other cultures not exposed to elevated glutamate. Conclusion: Since sequential synaptic connectivity can encompass extensive cortical regions, this study presents a potential additional contributor to the spread of damage resulting from glutamate excitotoxicity and should be considered in attempts to mitigate neurodegeneration.

Vast Topological Learning and Sentient AGI

2021 ◽  
Vol 08 (01) ◽  
pp. 81-111
Author(s):  
Stephen L. Thaler
Keyword(s):  
Human Brain ◽  
Cortical Neurons ◽  
Neural Nets ◽  
Neural Systems ◽  
General Intelligence ◽  
Associative Memories ◽  
Direct Experience ◽  
Environmental Input ◽  
New Concepts ◽  
Random Disturbances

A novel form of neurocomputing allows machines to generate new concepts along with their anticipated consequences, all encoded as chained associative memories. Knowledge is accumulated by the system through direct experience as network chaining topologies form in response to various environmental input patterns. Thereafter, random disturbances to the connections joining these nets promote the formation of alternative chaining topologies representing novel concepts. The resulting ideational chains are then reinforced or weakened as they incorporate nets containing memories of impactful events or things. Such encodings of entities, actions, and relationships as geometric forms composed of artificial neural nets may well suggest how the human brain summarizes and appraises the states of nearly a hundred billion cortical neurons. It may also be the paradigm that allows the scaling of synthetic neural systems to brain-like proportions to achieve sentient artificial general intelligence (SAGI).

scholarly journals Spatially resolved non-invasive chemical stimulation for modulation of signalling in reconstructed neuronal networks

2005 ◽  
Vol 3 (7) ◽  
pp. 333-343 ◽  
Author(s):  
Yulia Mourzina ◽  
Alfred Steffen ◽  
Dmitri Kaliaguine ◽  
Bernhard Wolfrum ◽  
Petra Schulte ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Network Architecture ◽  
Neuronal Networks ◽  
Network Formation ◽  
Microcontact Printing ◽  
Chemical Stimulation ◽  
Functional Coupling ◽  
Non Invasive ◽  
On Chip

Functional coupling of reconstructed neuronal networks with microelectronic circuits has potential for the development of bioelectronic devices, pharmacological assays and medical engineering. Modulation of the signal processing properties of on-chip reconstructed neuronal networks is an important aspect in such applications. It may be achieved by controlling the biochemical environment, preferably with cellular resolution. In this work, we attempt to design cell–cell and cell–medium interactions in confined geometries with the aim to manipulate non-invasively the activity pattern of an individual neuron in neuronal networks for long-term modulation. Therefore, we have developed a biohybrid system in which neuronal networks are reconstructed on microstructured silicon chips and interfaced to a microfluidic system. A high degree of geometrical control over the network architecture and alignment of the network with the substrate features has been achieved by means of aligned microcontact printing. Localized non-invasive on-chip chemical stimulation of micropatterned rat cortical neurons within a network has been demonstrated with an excitatory neurotransmitter glutamate. Our system will be useful for the investigation of the influence of localized chemical gradients on network formation and long-term modulation.

scholarly journals Xenotransplanted human cortical neurons reveal species-specific development and functional integration into mouse visual circuits

2019 ◽  
Author(s):  
Daniele Linaro ◽  
Ben Vermaercke ◽  
Ryohei Iwata ◽  
Arjun Ramaswamy ◽  
Brittany A. Davis ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Human Brain ◽  
Cortical Neurons ◽  
Single Cells ◽  
Functional Integration ◽  
List Type ◽  
Visual Responses ◽  
Mouse Cortex ◽  
Human Neurons ◽  
Species Specific

SummaryHow neural circuits develop in the human brain has remained almost impossible to study at the neuronal level. Here we investigate human cortical neuron development, plasticity and function, using a mouse/human chimera model in which xenotransplanted human cortical pyramidal neurons integrate as single cells into the mouse cortex. Combined neuronal tracing, electrophysiology, andin vivostructural and functional imaging revealed that the human neurons develop morphologically and functionally following a prolonged developmental timeline, revealing the cell-intrinsic retention of juvenile properties of cortical neurons as an important mechanism underlying human brain neoteny. Following maturation, human neurons transplanted in the visual cortex display tuned responses to visual stimuli that are similar to those of mouse neurons, indicating capacity for physiological synaptic integration of human neurons in mouse cortical circuits. These findings provide new insights into human neuronal development, and open novel experimental avenues for the study of human neuronal function and diseases.Highlights:Coordinated morphological and functional maturation of ESC-derived human cortical neurons transplanted in the mouse cortex.Transplanted neurons display prolonged juvenile features indicative of intrinsic species-specific neoteny.Transplanted neurons develop elaborate dendritic arbors, stable spine patterns and long-term synaptic plasticity.In the visual cortex transplanted neurons display tuned visual responses that resemble those of the host cortical neurons.

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