I haven’t read the entire thing yet, so maybe I am missing something, but isn’t the globus pallidus inhibitory? In this you stated that it amplifies signals. there should be a path from the cortex to the subthalamic nucleus that where the globus pallidus shuts down the idea fed to striatum. I like to think of the striatum as the dad, and the globus pallidus as the mom. Then the cortex is the idea that the kids(thalamus) come up with. The dad and mom both see the idea, and the mom always says no, unless the dad convinces her to do the thing. The globus pallidus internal can also send the thalamus to time out to suppress new ideas.
My main answer is that the “toy loop model”s here are pretty bad and shouldn’t be taken literally. I have an updated discussion here (posts 5-6 mostly), but even that has some issues; I made more progress in the last six months that I haven’t written up yet.
I’m more confident in the “‘Context’ in the striatum value function” section here. The convergence of many striatal neurons onto few “final answer” neurons (in both pallidum and SNr) seems pretty central to me. Kinda vaguely like the striatum is the final hidden layer, and pallidum / SNr / whatever neurons are “heads”, in a loose ML analogy.
To answer your question slightly, I’m working at a pretty high level (Marr’s “algorithm level”, I suppose) here. It’s possible to have a signal which is best thought of as exciting something, but is actually implemented by an inhibitory connection. For example, it could be “disinhibitory” (inhibiting an inhibitor). Swanson 2000 does indeed claim that pallidum-to-brainstem signals are disinhibitory, specifically by inhibiting the inhibitory striatum-to-brainstem signals.
But anyway, yeah, I would read this post as kinda “early attempt” rather than correct. A lot of the details are very much wrong. I’ll make the top-note more prominent.
I haven’t read the entire thing yet, so maybe I am missing something, but isn’t the globus pallidus inhibitory? In this you stated that it amplifies signals. there should be a path from the cortex to the subthalamic nucleus that where the globus pallidus shuts down the idea fed to striatum. I like to think of the striatum as the dad, and the globus pallidus as the mom. Then the cortex is the idea that the kids(thalamus) come up with. The dad and mom both see the idea, and the mom always says no, unless the dad convinces her to do the thing. The globus pallidus internal can also send the thalamus to time out to suppress new ideas.
My main answer is that the “toy loop model”s here are pretty bad and shouldn’t be taken literally. I have an updated discussion here (posts 5-6 mostly), but even that has some issues; I made more progress in the last six months that I haven’t written up yet.
I’m more confident in the “‘Context’ in the striatum value function” section here. The convergence of many striatal neurons onto few “final answer” neurons (in both pallidum and SNr) seems pretty central to me. Kinda vaguely like the striatum is the final hidden layer, and pallidum / SNr / whatever neurons are “heads”, in a loose ML analogy.
To answer your question slightly, I’m working at a pretty high level (Marr’s “algorithm level”, I suppose) here. It’s possible to have a signal which is best thought of as exciting something, but is actually implemented by an inhibitory connection. For example, it could be “disinhibitory” (inhibiting an inhibitor). Swanson 2000 does indeed claim that pallidum-to-brainstem signals are disinhibitory, specifically by inhibiting the inhibitory striatum-to-brainstem signals.
But anyway, yeah, I would read this post as kinda “early attempt” rather than correct. A lot of the details are very much wrong. I’ll make the top-note more prominent.