Not sure what level of detail you need, but the general idea is that the protein channelrhodopsin converts light to electrical activity. Electrical activity is how neurons in the brain convey information, so it lets you change their activity experimentally. In this case making a "false memory"
I guess what I don’t understand is how you can get the specificity you need out of all the cells in a particular area of the brain. Like: even if you know you want the fifth layer of the cortex in some known motor control area… can you really just activate some number of cells and it just works??
A good peer review comment 😬. Generally, you need some way to make expression specific to the cells you are interested in with genetic tricks. Cell type specific promoters, injecting viral expression vectors to specific areas, etc. Even then "light > activity" can be a sledgehammer approach.
Finally! My last big memory question is … I feel like I have a lot of memories that are neither “episodic” nor … any recognizable category. But like … fuzzier. My sense scanning the lit is that multiple memory systems was the order of the day quite recently. Is it still that way?
I will tap out on the details here as I am very much not a systems/cognitive neuroscientist. There are definitely different types though (episodic, semantic...others...) and there is not just a single brain region "in charge" of all types of memory
I’m glad my 1000% amateur question is not too embarrassing.
I think I’m finding that my snap judgments are biased against a lot of neuroscientific methods. I think I’ve overtrained on the critiques of fMRI I heard early in my career
Neuroscience covers lots of scales and we're all biased toward our preferred one. Lots of cognitive and systems level work relies on correlating neural activity to behavioral output. The huge power of optogenetics is giving some experimental control over activity to make assertions on causality
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In part because it seems to leave so much room for memory recall to be a creative act, which I am realizing I am quite keen on (from introspection!)
I think I’m finding that my snap judgments are biased against a lot of neuroscientific methods. I think I’ve overtrained on the critiques of fMRI I heard early in my career