I did my Ph.D. work on the cerebellum and proposed a theoretical model of reinforcement learning and can add some context for why this is a "big deal".
First, it represents a fundamental shift in how the cerebellum learns. For a long time, it was thought that the cerebellum learned liked a perceptron neural network, i.e. that an error signal was computed and used to change the strength of synapses within the cerebellum to result in the correct output signal to guide motor control (and, we know now, cognitive control). In other words, the cerebellum was a supervised learning machine [1]. But how these error signals were actually computed using the neuronal circuitry was never made clear; most arguments centered around the microcircuitry of the inferior olive. In a perceptron, an error signal is the difference between the correct output and the predicted output. But how is the "correct output" supplied?
As far as I know the first to propose the cerebellum learned by reinforcement learning was the famed cerebellum researcher Richard Thompson [2]. Unfortunately, the idea was only vaguely sketched out the field didn't take this very seriously and continued on with the general belief that the cerebellum learned by supervised learning.
To me and my collaborator, Tadashi Yamazaki, it seemed a more natural signal that the nervous system could capably supply would be a graded reward signal. Moreover, this meant we could interpret the structure of the cerebellum within the theoretical frameworks of reinforcement learning such as the actor-critic framework [3,4]. This is the second reason these finding are a big deal: the paradigm shift to the cerebellum being a reinforcement learning machine, if correct, will be a boon for building better models of it. In the last few years there has been some impressive work done with reinforcement learning in artificial neural networks that could be applied to models of the cerebellum, especially within context of the brain at large.
[1] Doya, Kenji "What are the computations of the cerebellum, the basal ganglia and the cerebral cortex" (1999)
[2] Thompson, Richard "The nature of reinforcement in cerebellar learning" (1998).
[3] Lennon, William "Towards more biologically plausible computational models of the cerebellum with emphasis on the molecular layer interneurons" (2015)
[4] Yamazaki and Lennon "Revisiting a theory of cerebellar cortex" (2019)
> most arguments centered around the microcircuitry of the inferior olive
If, like me, you wondered how a poor fruit has microcircuitry, well, I think they're actually talking about the Inferior Olivary Nucleus. Per Wikipedia:
> The inferior olivary nucleus (ION), is a structure found in the medulla oblongata underneath the superior olivary nucleus. In vertebrates, the ION is known to coordinate signals from the spinal cord to the cerebellum to regulate motor coordination and learning. These connections have been shown to be tightly associated, as degeneration of either the cerebellum or the ION results in degeneration of the other.
I'd like to hypothesize: the cerebellum "tunes" other circuits into alignment, which produces hebbian learning through synchronization. That sort of hebbian learning (novel synchrony between populations of presynaptic neurons) is both reinforcing and rewarding.
If I start from there and am looking to confirm this hypothesis (or disabuse myself from it), might you suggest a reference?
This is a great example of a niche banking solution which is far better than any traditional bank can provide. I think we'll see a lot more of this as banking APIs become more available.
My company is working on similar problem and solution for youth sports teams and clubs which are also non-profits (formally or informally).
Thats awesome! The debit card solution and 501(c)3 eligibility that hack club presents is genius and so often overlooked in fledgling youth sports and organizations. I hope that ground.work can find a way for fringe sports and teams to also get their organization finances in order as many sports businesses tend to focus only on the main priority sports. (I run an ultimate frisbee organization)
>This is a great example of a niche banking solution which is far better than any traditional bank can provide
Seems to me it is a traditional bank offering the banking services...only in authentic Silicon Valley style its being marketed exactly as you describe, a non traditional bank disrupting the status quo.
> I think we'll see a lot more of this as banking APIs become more available.
Available to whom, though? Companies with millions of dollars of capital or VC money?
I've been asking for, in the past decade, is a read/write API access to my personal account. I can make it work from there myself, and I can do it better than the bank. Hell, even just read-only access would streamline my banking and solve 90% of the use cases I have in mind. But no, it didn't happen, and it's not going to happen.
And I suspect why: because web and mobile apps are first and foremost a way for the bank to upsell financial products.
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Something to add to this that most non-neuroscientists don't realize is that the spinal cord is not just a bundle of wires that connect the brain to muscles. The spinal cord is a complex circuit that contains "central pattern generators" (CPG) that can produce rhythmic movement. When activated, these networks can be pushed into a dynamic state where they repeat the same movement repeatedly, e.g. walking. For more, look up the work by Sten Grillner on stingray CPGs.
One approximate way of looking at this is that the brain's motor cortex sends a "go" signal to the spinal cords CPGs and these start generating the signals to the muscles to walk. You can also think of motor control as hierarchical where as you go up the hierarchy. The bottom of the hierarchy are the muscles/actuators, then the neurons that stimulate the muscles, then the circuits in the spinal cord that have these CPGs and other "primitives", then primary motor cortex and further up the cortical hierarchy. At the higher levels of the cortical hierarchy are representations of whole movements, like moving your hand to mouth. As you descend the hierarchy, the neural signals control gradually more details components of the movement. For more, look up the work by Michael Graziano.
Are CPG the source of "muscle memory", ie reflexive actions? So much of physical training is to achieve the vaunted muscle memory as it allows unconscious (ie faster) reaction times.
I would argue that muscle memory has less to do with speed or strength and more to do with 'remembering' motion. But of course this is just based off personal experience and intuition so I have nothing to back this up.
Connecting this to the OP is that it looks like the stimulation is initially activating these CPGs -- all of the movement is happening based on control from the spinal cord alone. It's not clear how much communication is taking place between the motor cortex and the spinal cord in this patient.
the decerebrate cat experiments illustrate this perfectly (although perhaps people dont like to talk about it because of the ethics of the experiments)
Indeed. What's new is what sort of information is conveyed from the gut to the brain via the vagus nerve. Note: information is also conveyed in the other direction from the brain to the gut.
This study shows that your gut is equipped with environmental sensors (enteroendocrine cells) that can convey nutritional information from the gut to the brain on short time scales (~seconds or faster). It's like your gut's "eye" in that it can "see" what's going on, like sugars are present, and convey this to your brain.
I'm not an expert on the gut-brain field but I've always wondered where food cravings come from, especially specific ones that pregnant women often exhibit. E.g. craving dirt. My conclusion is that your body must have a way of sensing what nutrients you're ingesting and missing.
If I could downvote your comment I would because this is not an accurate synthesis of the article.
"more young, charismatic ivy league graduates" is not at all what the author describes. The author's thesis is that raising a Series A has requirements ranging between a Seed round which is based on, "the quality of the founders and the raw story that they can tell about their company and the future that company will create" and a Series B which is based on "[the] need to have accomplished a significant set of things that prove their ability to accomplish that future".
I know a (small) number of YC companies and they all have a "young, charismatic ivy league graduate" on board. I imagine there's some sort of subconscious bias at play here that equates those properties with "quality of the founders".
Be that as it may, if you're one of those people you can use it to your advantage and get away with less traction.
I know a large number of YC companies, and only a minority fit that description.
Being charismatic isn't entirely unrelated to one's ability to lead a company. You don't have to be slick, but projecting enough charm that people don't wander off while you're talking helps with hiring and sales.
You can learn to be acceptably charismatic if you put some effort into it. If Bill Gates and Jan Koum did it, you can too.
Young, charismatic ivy league grads are one specific instance of "the quality of founders ". Another, equally fitting one is, "A successful serial entrepreneur with an exit or two under their belt". Another, albeit seemingly outdated one is, "a former Googler". There are many ways a founder can be of high quality that are not ivy league grads.
Being a YC founder, I am not an Ivy league grad but a PhD drop-out who happens to have the combination of domain expertise, technical understanding, and charm.
Your poor conclusion of "ivy league grad" is ridiculous. If anything YC looks for doers not those that have.
If you would have said you were a high school dropout and poor communicator this would have made a point but PhD + charm is phenotypically similar to an attractive ivy grad so you’re kind of proving the point.
Please be aware this is your bias, your POV. You can't use it to prove your own point.
PhD is nothing similar to your connotation of Ivy League grad. The former requires years of sacrifice, ruined relationship, and missed experiences to master an esoteric part of science. The latter has the connotation of privilege.
