How is a brain able to support stable neural dynamics and yet remain flexible in order to adapt to changing contexts. Here’s our latest foray into exploring how the thalamus can help. 🧵1/16.

RT @bendfulcher: New preprint!.Why are long-range connectomic interactions in the cortex dominant in shaping dynamics in some experiments….

RT @bendfulcher: Applications for this (well-paid) postdoctoral position in our group in Sydney, Australia close in a few days. Anyone inte….

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RT @jmacshine: Back when I started my research group, I wanted to build @DrBreaky-esque computational models of the brain, but I knew I nee….

RT @JoshTan19: So excited for this work to be finally out. Thanks to all the co-authors for putting up with me and letting me talk about te….

RT @bendfulcher: New preprint by Rishi Maran @eli_j_muller . "Analyzing the Brain's Dynamic Response to Targeted Stimulation using Generati….

Big thanks to all my collaborators @jmacshine @DrBMunn @bingbrunton @eigensteve @giuliaabaracc @bendfulcher @medelero, Michelle Redinbaugh, Yuri Saalman.

Our findings demonstrate that the thalamus provides versatile control over cortical laminar and non-laminar flows characterizing conscious states – providing an essential feature for adaptive cognition. Heaps more in the paper if you’re interested!.

These changes can also be formulated as a flattening of an attractor landscape and show how the thalamus facilitates novel state formations.

Our biophysical model predicts matrix stimulation should recover non-laminar fluctuations seen in wake. We confirm these predictions in the macaque - finding stimulation of the matrix-rich central thalamus restores non-laminar cortical fluctuations and the waking state.

Some wonderful work in macaque monkeys under propofol anaesthesia showed that stimulating the central thalamus – abundant in matrix nuclei – restores consciousness. . But what dynamics are being restored?.

We then validated this finding using a previously developed large-scale biophysical model of the thalamocortical system showing increased laminarity under anaesthesia. But what about the thalamus’ role?

We first asked whether pharmacological manipulation of conscious brain states impacted laminarity. Human imaging data showed propofol anaesthesia disrupts non-laminar cortical dynamics while preserving laminar flow.

And an increase in stable laminar flow is seen following strong activity of core thalamic nuclei. But what about casual manipulation of these dynamics?

Turning back to the thalamus, these laminar dynamics tend to dominate in cortical areas receiving targeted core thalamocortical projections.

This laminarity is not captured by static correlation and Fourier spectral structure but is made up of dynamical modes with distinct timescales predictive of its future states.

Leveraging techniques from fluid dynamics we found spontaneous human fMRI data exhibits non-trivial fluctuations in laminarity.

To answer this, like a river – instead of tracking topography – which is still highly informative – we can characterise the flow of brain dynamics: which might be calm and largely laminar, or turbulent and non-laminar.

The intuition here is that some thalamocortical cells relay precise information to specific cortical regions, whereas others diffusely modulate ongoing cortical dynamics. But what type of dynamics do they modulate?