Developmental and evolutionary perspectives on thalamic function
Brain organization and function is a complex topic. We are good at establishing correlates of perception and behavior across forebrain circuits, as well as manipulating activity in these circuits to affect behavior. However, we still lack good models for the large-scale organization and function of the forebrain. What are the contributions of the cortex, basal ganglia, and thalamus to behavior? In addressing these questions, we often ascribe function to each area as if it were an independent processing unit. However, we know from the anatomy that the cortex, basal ganglia, and thalamus, are massively interconnected in a large network. One way to generate insight into these questions is to consider the evolution and development of forebrain systems. In this talk, I will discuss the developmental and evolutionary (comparative anatomy) data on the thalamus, and how it fits within forebrain networks. I will address questions including, when did the thalamus appear in evolution, how is the thalamus organized across the vertebrate lineage, and how can the change in the organization of forebrain networks affect behavioral repertoires.
25 years of DBS beyond movement disorders: what challenges are we facing?; Directional DBS targeting of different nuclei in the thalamus for the treatment of pain
On Thursday, 23rd of February, we will host Veerle Visser-Vandewalle and Marie Krüger. Marie Krüger, MD, is is currently leading the stereotactic surgery unit in St. Gallen but is on her move to join the team at UCL / Queensquare London. She will discuss “Directional DBS targeting of different nuclei in the thalamus for the treatment of pain”. Veerle Visser-Vandewalle, MD, PhD, is the Head of the Department of Stereotactic and Functional Neurosurgery at University Hospital of Cologne. Beside his scientific presentation on “25 years of DBS beyond movement disorders: what challenges are we facing?”, she will also give us a glimpse at the “Person behind the science”. The talks will be followed by a shared discussion. You can register via talks.stimulatingbrains.org to receive the (free) Zoom link!
Bidirectionally connected cores in a mouse connectome: Towards extracting the brain subnetworks essential for consciousness
Where in the brain consciousness resides remains unclear. It has been suggested that the subnetworks supporting consciousness should be bidirectionally (recurrently) connected because both feed-forward and feedback processing are necessary for conscious experience. Accordingly, evaluating which subnetworks are bidirectionally connected and the strength of these connections would likely aid the identification of regions essential to consciousness. Here, we propose a method for hierarchically decomposing a network into cores with different strengths of bidirectional connection, as a means of revealing the structure of the complex brain network. We applied the method to a whole-brain mouse connectome. We found that cores with strong bidirectional connections consisted of regions presumably essential to consciousness (e.g., the isocortical and thalamic regions, and claustrum) and did not include regions presumably irrelevant to consciousness (e.g., cerebellum). Contrarily, we could not find such correspondence between cores and consciousness when we applied other simple methods which ignored bidirectionality. These findings suggest that our method provides a novel insight into the relation between bidirectional brain network structures and consciousness. Our recent preprint on this work is here: https://doi.org/10.1101/2021.07.12.452022.
Visual processing of feedforward and feedback signals in mouse thalamus
Traditionally, the dorsolateral geniculate nucleus (dLGN) of the thalamus has been considered a feedforward relay station for retinal signals to reach primary visual cortex. The local and long-range circuits of dLGN, however, suggest that this view is not correct. Indeed, besides the thalamo-cortical relay cells, dLGN contains local inhibitory interneurons, and receives not only feedforward input from the retina, but also massive direct and indirect feedback from primary visual cortex. Furthermore, it is one of the earliest processing stages in the visual system that integrates visual information with neuromodulatory signals.