Our 7th meeting was held on Wednesday 27.05.2020 on zoom.

We started our discussion of Wang, X. J. (2010). “Neurophysiological and computational principles of cortical rhythms in cognition” (Xiao-Jing Wang, Physiological reviews, 2010). We went through parts 1-4 of the review. This part focuses on the many different mechanisms, from single cells to connected networks, that can create oscillations. Several questions came up during the discussion. First, some oscillations are described using the same name in different parts of the brain, and it is not clear that they represent the same phenomenon. For instance, theta waves which are separated to hippocampal theta and frontal midline theta, or gamma waves that occur in the hippocampus but also in the motor and visual cortices. On the other hand, alpha, mu and tau, are all rhythms in the same frequency band that are suppressed after the onset of a stimulus, yet they have been given different names because they occur in different parts of the cortex. One specific question that was raised is about the phase response curves of neurons, which make up a significant part of the theoretical discussion, rely on the assumption that the neuron receives a constant input which makes it fire repetitively at a constant rate. However, neurons rarely are in that state, so the PRC are useful to get an intuition about the effect of neuronal interaction. Another question regarded the seeming endless possibilities of neuronal dynamics. First, are all these possibilities attested in nature (probably not)? Second, the group of Eve Marder showed that in crabs the functional oscillations are "controlled" in the sense that many different crabs show the same sort of oscillation but use completely very combinations of channels to create that. Another model of interest was that of oscillations that arise in sparsely connected networks when the input to the network is strong enough. This model is interesting, because it is consistent with claims that gamma oscillations in the visual cortex, which depend to a large extent on the specific properties of the stimulus, are the result of giving very strong inputs to the visual cortex, and do not represent its normal activity. We decided to continue the discussion into this review next meeting, adding another paper about the suggested functional roles of oscillations.

 

 

Participants

Nora Vreiler

Gal Vishne

Nir Ofir

Lorenzo Guarnieri

Noa Rahamim