The Nature of Code: Simulating Natural Systems with Processing

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What olfactory cues do mice use to landmark their HD system? Previous work indicates that rodents can use a variety of odors, including self-generated odors, conspecific odors, and other non-animal odors, to guide spatial navigation 36, 37, 61. In our experiments, for each mouse, its first open-field exposure began on a new floor, which had never been explored by another mouse, meaning the mice had to use cues intrinsic to the floor or that were self-generated. where, \(\triangle\)PFD is defined as the change in the preferred firing direction (in degrees) for each HD cell following reintroduction into the arena, and \(\triangle {{{{{{\mathrm{cue}}}}}}\; {{{{{\mathrm{is}}}}}}}\) defined as the extent (either 90° or 180°) that the visual cue was rotated. Floor rotation We next tested the stability of HD cells in blind mice and the extent to which their HD cell network was able to reliably encode head direction. First, we found that the preferred direction of HD cells remained stable over a single 10 min recording session (Fig. 1d), and across repeated exposure to the same arena (Fig. 1e), with levels of stability similar to what we found for sighted animals in the light (Supplementary Fig. 1). Next, we examined whether the HD cell network in ADn of blind mice was providing a reliable readout of the animal’s head direction by performing a decoding analysis 41, 42. We found that simultaneously recorded cells provided robust and stable decoding of HD (Fig. 1f). Therefore, in blind rd1 mice, HD cells are highly tuned and provide an accurate readout of head direction.

Next, we compared several metrics for HD cell responses between blind and sighted mice. For vector length, tuning width, and mutual information, each group of mice was statistically different from one another, demonstrating the following hierarchy in HD tuning refinement: WT L> rd1 > WT D (Fig. 2c; Supplementary Fig. 2a, b). Furthermore, if we limited our analysis in WT animals to HD cells that were recorded in both light and dark environments, and performed paired statistical tests, we found a similar relationship with HD tuning being significantly impaired for WT animals in the dark compared to the light (Supplementary Fig. 2c). Thus, sighted mice exhibit significant impairment in HD cell tuning when placed in the dark, with a level of impairment much more severe than is seen in blind animals, for whom HD cell tuning—although slightly less refined than in sighted animals in the light—is robust and stable. Prior visual experience leads to refined HD cell tuning in blind adult mice To directly test whether olfactory inputs were required for stabilizing HD cell tuning in blind mice, we ablated olfactory sensory neurons (OSNs) and examined the effect on HD cell tuning. To ablate OSNs, we used a previously established chemical lesioning method 48 (see Methods). To ensure that this method was effective at ablating OSNs and severely impairing olfaction, we developed an olfactory place avoidance task in which a mouse was placed in a two-chamber arena, with one of the chambers housing an aversive olfactory substance (3-methyl-1-butanethiol 49) and the other chamber housing a neutral olfactory substance (distilled H 2O; Fig. 5b; see Methods). Mice with intact OSNs completely avoided the chamber containing the aversive olfactory substance (Fig. 5b, c). In contrast, following OSN ablation, mice showed no preference between the two chambers (Fig. 5b, c). Having established a method to reliably ablate olfaction, we tested the effect of olfactory ablation on HD cell tuning in blind animals. Olfactory ablation resulted in complete loss of HD cell tuning in ADn of blind mice (Fig. 5d, e; we pooled together rd1 and Gnat1/2 mut mice as OSN ablation affected both similarly (Supplementary Fig. 5c, d)). The percent of ADn cells that passed the criteria for being designated as HD cells drastically decreased for blind mice following olfactory ablation (Fig. 5e, Supplementary Fig. 5e, f). For some experiments, whiskers were intact during olfactory ablation, while in other animals, whiskers were ablated prior to olfactory ablation, but in both cases, olfactory ablation resulted in complete loss of HD cell tuning (Supplementary Fig. 5), again indicating that, at least in this experimental paradigm, the vibrissal system was not being used to tune HD cells. These results show that blind mice use olfactory cues to anchor their HD system. Best of the Web: 60 years after JFK's death it is more and more apparent that Kennedy was a victim of a palace coup - spearheaded by Vice-President JohnsonTheoretical physicist, Dr. James Gates, Jr. The idea that we live in a holographic universe that uses a form of quantum "computer code" to create the physical reality is not a new idea. In the 1940s, some physicists suggested that we live in a "computer generated" universe. In the video at the end of this article, physicists James Gates talks about this form of computer code, which he refers to as "adinkras".

Coronavirus fragments can persist in the body of a person for up to a year: an estimated 65 million people worldwide suffer from the consequences At this level, our artwork will look like flashes of electrical currents. This analogy of how a computer works is similar to how our minds and consciousness create our illusionary external reality. ... World's biggest iceberg starts moving for first time in decades — and it could cause some serious problemsWe next examined the effect that olfactory ablation had on HD cells in blind animals. To test this, used an alternative method to reliably identify HD cells in ADn regardless of whether or not they exhibited strong tuning preferences for head direction. Previous work 50 noted that HD cells in ADn exhibit highly distinctive autocorrelograms. Similarly, we found that HD cells in ADn maintain their distinctive autocorrelograms in blind animals and following OSN ablation (Fig. 5f, Supplementary Fig. 5). Following Veijo and Peyrache 50, we implemented a machine learning approach, using Extreme Gradient Boosting 51 (XGB) to classify neurons as either HD or non-HD cells based on the shape of their autocorrelogram. First, we used our standard method to define cells as either HD cells (which rely on cells having highly selective preferred firing directions for a given head direction; see Methods) or non-HD cells, and trained the classifier using an equal number of HD and non-HD cells from WT L mice. To assess model generalizability, here, the classifier was validated on data from blind controls (pooled rd1 and Gnat1/2 mut mice; Fig. 5g). Furthermore, the classifier characterized a similar percentage of cells in ADn in blind animals with intact OSNs and following OSN ablation (Fig. 5h; see Methods). We, therefore, used the classifier to define HD cells in ADn of blind mice following OSN ablation, allowing us to compare their response properties with HD cells in blind animals with intact OSNs. By using the same model to identify HD cells in blind controls and OSN ablated animals, we found that OSN ablation led to a significant decrease in vector length (Fig. 5i). These results indicate that removing olfaction from blind animals results in untuned HD cells in ADn. Olfaction can modulate HD cell tuning in sighted animals Full size image The vibrissal system is not required for head direction cell tuning in blind animals in the open-field environment

We find that—for normally sighted and blind animals—the removal of both visual and olfactory inputs causes the ‘hill of activity’ within HD attractor network to drift independently from the animal’s true head direction (i.e. the preferred direction of all simultaneously recorded cells drifts coherently). For some animals, there was a significant correlation between angular head velocity and angular drift velocity of PFDs. Furthermore, we found that in the absence of vision and olfaction, the decoded angular velocity (AHV) under-signaled the true AHV. To assess floor-controlled changes in PFDs of HD cells, a protocol similar to the visual cue rotation described above was adopted, except where the floor of the arena was rotated. For these experiments, to avoid possible interference of odor markings across different animals, a brand new floor was used for each mouse. At the same time, to give mice the opportunity to use olfactory odors on the floor, the floor of the arena was not cleaned between exposures. The extent to which floor rotations influenced the PFD of HD cells across animals was computed using Eq. ( 1). For cue/floor rotation sessions, 10,000 shuffles were generated using re-exposure sessions where animals were re-exposed to the same environment in the absence of any manipulation. To generate the gain values expected by chance, the gain was computed after randomly applying the experimental cue/floor rotation angles to the re-exposure data. Olfactory sensory neuron (OSN) ablation For example, when we paint a picture using a computer software, the core state of the colors and shapes in the picture are basically made of ones and zeros. We do not see our picture as ones and zeros, because the central processing unit (CPU) and its counterparts process the binary codes as colors and shapes. The greatest thing about binary codes is that there are no limits to their combinations. ... Next Pandemic Propaganda: The "Big One," Nipah, Ebola and Marburg, SARS1, Machupo, "Vampire Virus", Disease X

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Air Force officer breaks silence on 'red, glowing UFO the size of a football field' hovering at low altitude over California space launch base Upon placing blind adult rd1 mice in the open-field environment, we found robust HD cell tuning (Fig. 1b; n = 151 HD cells recorded from 13 animals, with 80.7% of recorded cells in ADn defined as HD cells; see Methods). Similar to what has been described for sighted animals, we found that rd1 mice evenly sampled all angular directions in the environment and possessed HD cells that exhibited preferred firing directions that spanned all head directions (Fig. 1c).

where I refers to the information content in bits/spike , P j is the probability of occupying bin j, λ j is the mean firing rate in bin j, and λ is the in-session mean firing rate of the cell. Preferred firing direction (PFD): Similar to Lozano et al. 97, PFD was defined as the angular bin with the highest normalized spike counts, whereas the mean PFD refers to the circular mean of angles. In Fig. 1e, stability was assessed based on the circular correlations of mean PFDs of exposure 1 and 2 across all recorded animals. Circular statistics were computed using the astropy module (v5.1) in Python. Intraclass correlation (ICC) Archaeologists unearthed a pot of copper coins in first major discovery at Mohenjo Daro in Pakistan, in 93 years where dir represents the set of possible angular head directions, and spk represents the spike counts of simultaneously recorded HD cells within a 200 ms time window in this instance. Bayesian decoding was used to predict the HD of animals in the second half of a recording session based on priors generated from tuning curves in the first half. The mean absolute decoding error was computed as the absolute difference between the decoded angle and the actual angle over the decoded time window. Isomap projection In my book titled Staradigm (published in 2011), I mentioned about this idea and roughly explained how it worked. It is great to finally hear that physicists of today are finding evidence that the Universe is a giant hologram.When we paint a picture or model a three dimensional object using computer software, all the instructions are processed by the CPU and its counterparts before they are projected onto the screen. This process happens almost instantaneously, and it shows that instructions are processed by the CPU before they are used to create the computer generated object. In a sense, our picture or three dimensional model is nothing more than a perception of the CPU. Our results indicate that vision and olfaction can be used, either independently or in tandem, to stabilize HD cell tuning. Visual signals are believed to enter the HD system via inputs from the visual cortex to the post-subiculum and retrosplenial cortex 12. With respect to olfactory inputs, the pathway into the HD system remains unclear, though direct projections from the olfactory bulb and piriform cortex to the entorhinal cortex 54, 55 could, in turn, reach ADn via post-subiculum, which is reciprocally connected to the entorhinal cortex and ADn 56. Alternatively, olfactory signals could reach the HD system indirectly via the projection of the post-subiculum to the lateral mammillary bodies, which constitute the main subcortical input to the ADn 12. Future studies examining these pathways in more detail in both sighted and blind mice will be required to develop a better understanding of the circuitry involved. Hubel and Wiesel discovered a critical period during development for ocular dominance plasticity in the visual cortex 66, and similar critical periods have been shown to exist for many other sensory systems and behaviors 67. Here, we provide evidence of a critical period in the refinement and maturation of the HD system in ADn that depends on visual inputs in the period shortly after eye-opening—the evidence being that rd1 mice, who have attenuated vision upon eye-opening before going blind around P30 40, 47, have more refined HD cell tuning as adults than congenitally blind Gnat1/2 mut mice. Both rd1 and Gnat1/2 mut mice go blind due to problems with retinal photoreceptors. rd1 mice go blind as a result of photoreceptor degeneration caused by a mutation in phosphodiesterase in rod photoreceptors (due to a mutation of the Pde6B gene), which initially leads to rod death followed by cone death, and this is a commonly used mouse model of retinitis pigmentosa 39. Gnat1/2 mut mice are blind as a result of mutations in both rod and cone forms of the alpha subunit of the G-protein transducin (due to mutations in both Gnat1 and Gnat2 genes), resulting in nonfunctioning rod and cone photoreceptors (see Methods). As the mutated genes in both mouse lines are predominantly expressed in photoreceptors, it is likely that the difference in HD cell tuning in blind adult Gnat1/2 mut vs. rd1 mice is a direct result of the timing of the onset of vision loss (congenital vs. ~P30). We thus propose that vision around the time of eye-opening allows the HD cell system to stabilize (i.e., upon eye-opening, vision enables HD cells to exhibit heightened stability in their preferred direction tuning 29, 30), and this stability results in refinement and maturation of the HD network, such that though both rd1 and Gnat1/2 mut are equally blind as adults, rd1 mice have more refined HD cell tuning. These findings are consistent with multisensory studies in the superior colliculus, which showed the importance of vision during development for enabling the generation of normal auditory space maps 43, 44, 68. Attractor dynamics in the presence and absence of anchoring external sensory inputs If we look at the computer from the outside, our artwork looks solid. If we take apart the outside layers of the computer and watch in slow motion how its hardware works beyond the microscopic level, we will see that it is made of vast streams of electrical currents. Electrical currents are another form of energy.