Spindle Neurons, Salience Network, & Social Behaviors

In this episode we explore spindle neurons, also known as von Economo neurons (VENs), discovered by Constantine von Economo in the 1920s. These large, cylinder-shaped cells, found in the anterior cingulate cortex (ACC), anterior (or called frontoinsula) insula, and rarely the dorsolateral prefrontal cortex (DLPFC), are crucial for rapid communication in social behaviors. Three key points stand out: first, spindle neurons are located exclusively in the ACC and insula, the core hubs of the salience network, which is disrupted in autism as early as six weeks of age, as shown in a UCLA study. Second, these neurons are primarily involved in social behaviors, underpinning complex interactions in humans and other social species. Third, they are rare, found only in highly social animals like great apes, cetaceans, and possibly elephants, highlighting their evolutionary significance. In autism, increased spindle neuron density in the insula of children aged 4–14 is linked to early brain overgrowth, though this normalizes in adulthood due to pruning.

The salience network, driven by the ACC and anterior insula, relies on spindle neurons to process relevant stimuli, integrate sensory data, and guide social-emotional responses. In autism, hyper-connectivity between the insula and sensory regions causes sensory hypersensitivity, while hypo-connectivity with prefrontal areas, including the DLPFC, impairs social cognition and adaptive behaviors. This disrupts the network’s ability to switch between the default mode network and executive functions, often trapping autistic individuals in an internal world. Spindle neurons are also linked to disorders like frontotemporal dementia, schizophrenia, Alzheimer’s, and emotional dysregulation.

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0:00 Chroma Light Devices, use "autism" for 10% discount

3:10 Spindle Neurons; Interesting Point #1: Salience Network

6:03 Interesting Point #2: Rapid Communication & Social Behaviors

7:11 "rediscovery" of Spindle Neurons in 1990s by John Allman

8:30 Interesting Point #3: Highly Social Species

10:57 Neuropeptide Y & Monoamine- Dopamine & Serotonin

11:45 Morphology of Spindle Neurons & In Utero-Children; Social Learning

12:54 Species with Spindle Neurons

14:47 Small Clusters within the dlPFC

15:08 Salience Network, ACC, Anterior Insula; Fulcrum for Default Mode and Executive Networks

22:48 Daylight Computer Company, use "autism" for $25 discount

27:08 Diseases/Conditions associated with Spindle Neurons

29:26 The Autistic Phenotype (!!) -- The Whole Reason for the Podcast

32:25 Reviews/Ratings, Contact Info

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