Cortical Hierarchy

2023-09-19:

Cortical Hierarchy #

• [A role for the serotonin 2A receptor in the expansion and functioning of human transmodal cortex]

• The genie in the bottle-magnified calcium signaling in dorsolateral prefrontal cortex (Arnsten et al. 2021)
  • 
    • LIP = lateral intraparietal area (in the parietal association cortex). MT = medial-temporal area. ERC-HPC = entorhinal-hippocampal
    • Sensory cortical areas have a timescale of ~65-75 ms
    • PFC assocation areas: 125-200 ms
    • ACC: 250-350 ms
    • EC: up to 20 seconds!
      • I wonder if this is related to the significance of Theta in the hippocampus and how it’s slower than anything like αβγ
    • Hierarchical Heterogeneity across Human Cortex Shapes Large-Scale Neural Dynamics (Dermitas et al. 2020)
    • A hierarchy of intrinsic timescales across primate cortex (2015)
      • This gets into that Cabezas stuff a bit regarding sensory-fugal homogeneity vs. heterogenity and structural connectivity
  • there is a near perfect correspondence between the cortical hierarchy and the pattern and sequence of tau pathology in AD… while the rostral cingulate areas are a focus of pathology in mood disorders such as depression.
  • Core Differences in Synaptic Signaling Between Primary Visual and Dorsolateral Prefrontal Cortex
    • V1 neuronal firing to visual stimuli depended on AMPA receptors, with subtle NMDA receptor contributions, while dlPFC depends primarily on NMDA receptors.
      • In V1, cAMP increases neuronal firing. HCN channels are located on distal dendrites and enhanced cell firing.
      • In dlPFC, HCN and PDE4A are concentrated in thin spines and cAMP-HCN gates inputs and weakens firing.
  • For permissive depolarization of the PSD in dlPFC neurons, rather than AMPA, they say, it’s contributed by α7 nAChR and M1 AChR.
    • Idk what this “permissive + persistent firing” they’re talking about is but yeah, that sure is a lot of Ca2+ and would achieve that.
      • But like, only non-GluR2-containing AMPAR would ever do that in the first place.
    • M1 closes M-type KCNQ channels
  • These powerful cholinergic actions in dlPFC contrast with more subtle effects in V1, where nicotinic receptors are restricted to presynaptic thalamic inputs in layer IV, and to interneurons [180], and acetylcholine has a more classic, modulatory role, e.g., enhancing responses during attention
• NMDAR Neurotransmission Needed for Persistent Neuronal Firing: Potential Roles in Mental Disorders (Yang, Arnsten, et al. 2021) another classic Arnsten PFC study on delay cells and whatnot.
  • Increased NR2B down the hierarchy as you approach BA25.