This technique takes a dead brain and permeates it with a transparent hydrogel matrix to keep proteins and nucleic acids in place. Then it removes the lipids. I guess the lipids are all that makes the brain opaque. At this point the brain is transparent but maintains its original structure so you can still label the proteins and nucleic acids.
A rat was implanted with a 32-unit microelectrode cortical array in either M1 or S1. The rat was then trained to choose between two alternatives based on external stimuli.
Meanwhile, another rat was implanted with 6 stimulating electrodes in the same area as the first rat. It was trained to choose between the same two alternatives based on a stimulation pattern conveyed via the electrodes.
Then the signals recorded from the first rat’s brain were processed ald sent into the second rat’s brain. Both rats were trained together and both were rewarded when both made the right choice. The second rat learned to make the same choice as the first rat 60% of the time.
Excerpt from the abstract: “We genetically labeled and manipulated MrgprA3+ neurons in the dorsal root ganglion (DRG) and found that they exclusively innervated the epidermis of the skin and responded to multiple pruritogens. Ablation of MrgprA3+ neurons led to substantial reductions in scratching evoked by multiple pruritogens and occurring spontaneously under chronic itch conditions, whereas pain sensitivity remained intact.”
Paraphrasing/adding to the article abstract: prevailing theory suggests that long-term memories are encoded via a two-phase process requiring temporary involvement of the hippocampus followed by permanent storage in the neocortex. However this group found that, even weeks later, after the memories are supposed to be independent of the hippocampus, they could disrupt recall by briefly suppressing hippocampal CA1. The suppression must be brief; if they suppress CA1 for a long time recall works again. This suggests that, long after memory formation, the memory is not primarily stored in the hippocampus, but the hippocampus is still somehow involved in recall. The research also implicates anterior cingulate cortex in recall. Abstract after the break.
Berger, Hampson, Song, Goonawardena, Marmarelis, and Deadwyler created a system for recording from and stimulating up to 32 neurons at once. The system learned a model to predict firing of some hippocampal CA1 neurons given some inputs from CA3, and could be “played back” later.
From the abstract: … we determine synaptic connectivity between nearby layer 2/3 pyramidal neurons in vitro, the response properties of which were first characterized in mouse visual cortex in vivo. We found that connection probability was related to the similarity of visually driven neuronal activity. Neurons with the same preference for oriented stimuli connected at twice the rate of neurons with orthogonal orientation preferences. Neurons responding similarly to naturalistic stimuli formed connections at much higher rates than those with uncorrelated responses. Bidirectional synaptic connections were found more frequently between neuronal pairs with strongly correlated visual responses….
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