Thread by @kfshinozuka

new pre-print: LSD reconfigures the frequency-specific network landscape of the human brain



🧵 (1/n) biorxiv.org/content/10.110…

fMRI studies have consistently shown that psychedelics decrease within-network connectivity and increase within-network connectivity in the brain. however, few studies have examined the effect of psychedelics on brain networks *at specific frequencies.* (2/n)

a previous MEG study (which measures the brain's magnetic fields) showed that psilocybin reduces the activation of 7 different networks in a range of frequency bands. however, this analysis didn't correct for "broadband" activity, which you can think of as background noise. (3/n)

the FREQuency-resolved variant of Network Estimation via Source Separation (FREQ-NESS) is able to isolate frequency-specific connectivity from broadband connectivity. prior applications showed that playing a 2.4 Hz sound reorganizes brain networks oscillating at 2.4 Hz. (4/n)

FREQ-NESS is able to identify how "prominent" different frequencies of brain activity are, as well as the networks of brain regions that are connected at those frequencies. (5/n)

applying FREQ-NESS to MEG data on LSD, we find that LSD significantly increases the prominence of high alpha frequencies (12.1, 13.3 Hz) across multiple conditions: eyes-closed resting-state, eyes-open resting-state, listening to music (eyes-closed), and watching a video. (6/n)

this is an intriguing result because previous studies showed that LSD decreases the power (i.e., amplitude) of all frequency bands, including high alpha. however, these power analyses mostly failed to correct for broadband noise... (7/n)

OTOH, FREQ-NESS captures the connectivity that is *specific* to individual frequencies, separate from broadband noise. so, LSD *increases* within-network connectivity at high alpha. while previous studies showed that LSD only ever decreases within-network connectivity... (8/n)

our result paints a more nuanced picture: changes in within-network connectivity depend on the frequency of brain activity. (9/n)

we also found that, on LSD, the high alpha networks engage more occipital (i.e., visual) regions in the brain, and low beta networks expand over temporal and occipital cortices. (10/n)

we interpret this reorganization of the brain network landscape in terms of disruptions in top-down regulation of brain activity, elevated thalamocortical connectivity, and aberrations in temporal lobe activity in schizophrenia. (11/n)

a big thank you to my collaborators: @Red92Mattia @CColeman_Neuro @LeorRoseman @MendelKaelen suresh muthukumaraswamy, @ProfDavidNutt @RCarhartHarris @PVuust morten kringelbach, and @LeonardoBo92 (12/12)