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[0] Foster DJ, Wilson MA, Reverse replay of behavioural sequences in hippocampal place cells during the awake state.Nature 440:7084, 680-3 (2006 Mar 30)

[0] Soetedjo R, Fuchs AF, Complex spike activity of purkinje cells in the oculomotor vermis during behavioral adaptation of monkey saccades.J Neurosci 26:29, 7741-55 (2006 Jul 19)

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ref: -2017 tags: locality sensitive hashing olfaction kenyon cells neuron sparse representation date: 01-18-2020 21:13 gmt revision:1 [0] [head]

PMID-29123069 A neural algorithm for a fundamental computing problem

  • Ceneral idea: locality-sensitive hashing, e.g. hashing that is sensitive to the high-dimensional locality of the input space, can be efficiently solved using a circuit inspired by the insect olfactory system.
  • Here, activation of 50 different types of ORNs is mapped to 50 projection neurons, which 'centers the mean' -- concentration dependence is removed.
  • This is then projected via a random matrix of sparse binary weights to a much larger set of Kenyon cells, which in turn are inhibited by one APL neuron.
  • Normal locality-sensitive hashing uses dense matrices of Gaussian-distributed random weights, which means higher computational complexity...
  • ... these projections are governed by the Johnson-Lindenstrauss lemma, which says that projection from high-d to low-d space can preserve locality (distance between points) within an error bound.
  • Show that the WTA selection of the top 5% plus random binary weight preserves locality as measured by overlap with exact input locality on toy data sets, including MNIST and SIFT.
  • Flashy title as much as anything else got this into Science... indeed, has only been cited 6 times in Pubmed.

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ref: -2019 tags: mosers hippocampus popsci nautilus grid cells date: 02-12-2019 07:32 gmt revision:1 [0] [head]

New Evidence for the Strange Geometry of Thought

  • Wow. Things are organized in 2d structures in the brain. The surprising thing about this article is that only the hiippocampus is mentioned, no discussion of the cortex. Well, it was written by a second year graduate student (though, admittedly, the writing style is perfectly fine.)

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ref: -0 tags: retinal ganglion cells neural encoding Farrow date: 07-31-2013 16:21 gmt revision:0 [head]

PMID-21273316 Physiological clustering of visual channels in the mouse retina

  • Anatomy predicts that mammalian retinas should have in excess of 12 physiological channels, each encoding a specific aspect of the visual scene.
  • Although several channels have been correlated with morphological cell types, the number of morphological types generally exceeds the known physiological types.
  • Here, we attempted to sort the ganglion cells of the mouse retina purely on a physiological basis.
  • Result: The optimal partition was the 12-cluster solution of the Fuzzy Gustafson-Kessel algorithm.
    • This might be useful elsewhere ...
  • Farrow Lab is responsible for the 11,011 electrode array.

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ref: Foster-2006.03 tags: hippocampus memory place cells reverse replay Wilson date: 03-06-2009 17:53 gmt revision:1 [0] [head]

PMID-16474382[0] Reverse replay of behavioral sequences in hippocampal place cells during the awake state.

  • wow: they show compressed reverse replay of firing sequences of hippocampal place cells during movement. While the rat is awake, too!
  • recorded up to 128 cells from the rat hippocampus; 4 animals.
  • the replay occurred while the rat was stopped, and lasted a few hundred milliseconds (~300).
  • phenomena appears to be very common, at least for the rats on the novel tracks.
  • replay events were coincident with ripples in the hippocampal EEG, which also occurs during sleep.
    • however, during slow-wave sleep, the replay was forward.
  • they offer a reasonable hypothesis for the reverse replay's function: it is used to propagate value information from the rewarded lcoation backwards along incoming (behavioral) trajectories.
    • quote "awake replay represents efficient use of hard-won experience."


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ref: Soetedjo-2006.07 tags: cerebellum purkinje cells complex spike saccade date: 12-09-2008 18:46 gmt revision:2 [1] [0] [head]

PMID-16855102[0] Complex spike activity of purkinje cells in the oculomotor vermis during behavioral adaptation of monkey saccades.

  • central conclusion: that change in complex spike rate correlates with the sign of scaccade error, but not the magnitude.
  • analysis is far more complicated than what this conclusion seems to require, though ... or maybe it is just too late for me.


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ref: notes-0 tags: VOR OKR climbing_fibers cerebellum purkinje cells date: 02-05-2007 23:45 gmt revision:1 [0] [head]

  • Motor Coding in Floccular Climbing fibers
  • On climbing fiber signals and their consequences 1996, review
  • The site of a motor memory shifts with consolidation
  • Learning in a simple motor system (February 2006)
    • in the abstract: "we propose that short-term motor memory is initially stored in the cerebellar cortex, and during consolodation the motor memory locus shifts to include a brainstem site"
      • ISO learning as a method of consolodation, reflex-adatpation and internalization? that would be cool.
    • a good diagram of the system for the lateral rectus
    • due to its pivotal nature, motor learning may have been one of the first forms of learning to be implemented by biology. "universal in freely-moving animals"
    • these authors define it as procedural - does not require conscious attention (but it can be influenced by it)
    • eye movements procedurally simpler than arm movements, which I've spent some time looking at.
      • lately, I've been having to do a lot of this, after my glasses lost one earpeice and have been moving about since :) slight changes in the angles of the lenses are very noticeable.
    • I thought that the theory for this system would be complete by now, and ready for the application to more complicated motor movements, but this is not so. The thoeries are still a bit controversial, and require a molecular understanding.
---- Description of the system: see figure. need to label this on the slides. (comment: I'm sure many of you know this better than i, but for review ...) need diagram of the direction that the eyes turn, including the lateral/medial rectus muscles. Note that the eyes are stabilized in the two other directions - pitch and roll. here we study yaw, but people have demonstrated the same effects in the other directions. { cat and human have gain < 1, monkey just about 1 (perfect) - humans require extra input, via OKR} - basic circuit known since 1967 (Eccles). - Maekawa and Simpson: the cerebelar purkinje cell recieves climbing fiber input from the inferior olivary nucleus that encodes visual information. - information about ongoing movements arrives at the lateral vestibulocerebellum via mossy fivers from the dorsolateral pontine nuclei. - some mossy fibers also carry visual information. - purkinje cells project directly back to the vestibular nuclei.