Heterosynapic potentiation for Hebbian-based graphs?

[indigorose1]

Correct me if I'm wrong, but I haven't been seeing anything about the strengthening of edges analogous to heterosynaptic potentiation. Isn't this an important part of learning/memory/association? Has anyone seen a paper about graphs that addresses this?

[yaxigeigei]

If vertices are neurons and edges are synaptic strength, the change caused by heterosynaptic plasticity is indistinguishable to that caused by homosynaptic plasticity. Thus we will not be able to analyze it unless the information of neuronal activities are incorporated into the graph (e.g. generating edge attribute of homo/hetero). In practice(1), it is hard to characterize homo- and/or hetrosynaptic plasticity at the scale large enough for meaningful graph analysis.

(1) Heterosynaptic Structural Plasticity on Local Dendritic Segments of Hippocampal CA1 Neurons, 2015

[indigorose1]

That's definitely true for the types of graphs we've been talking about in class, but I was more referencing the paper that Erika, William, and Duo presented the other day: An investigation of Hebbian phase sequences as assembly graphs, which operates on a scale fine enough to consider connections of cell assemblies in sequence, which might be altered slightly by considering different types of potentiation.

[yaxigeigei]

Thank you for your interests in the paper we presented. You are right that we may be able to reveal something interesting if different types of plasticity can be resolved. However, given the limitation of single unit extracellular recording there is no way to get such information. On the other hand, methods that are able to get plasticity information can only sample, at most, several neurons (or dozens synapses) simultaneously and are hard to implement in behaving animal.

[indigorose1]

Ah, I'm sorry, I didn't connect your username to your name, otherwise I wouldn't have addressed you in the third person. And yeah, I understand that the methods presented in this paper don't have the necessary resolution; I get that, but I was talking about the theoretical framework which they referenced: that of neutron assemblies and synchronised firing.

[yaxigeigei]

Just a little aside. One idea is that heterosynaptic plasticity is unlikely to occur in vivo. Previous experiments about this phenomenon were mostly done using artifical and extreme induction protocols which were not quite physiological. However, a general form of heterosynaptic plasticity may be defined under the framework of synaptic tagging (which is very interesting and important).