Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.08.19.608693

Intermittent Theta Burst Stimulation Drives Bi-Directional Changes in Excitability in Prefrontal Cortex

Salimi, M.·Nazari, M.·Mishler, J.·Mishra, J.·Ramanathan, D.
View original source ↗Export metadata ↓

Abstract

Intermittent Theta Burst Stimulation (iTBS) is a patterned stimulation protocol FDA-cleared to treat depression, yet its outcomes are variable and mechanistically unclear. Here, using a combination of calcium imaging, histology, optogenetics and behavior, we show that one parameter of iTBS, the inter-train interval (ITI) between stimulation trains, plays a critical role in modulating GABAergic (and especially parvalbumin) neuronal activity, modulating subsequent neuronal plasticity and antidepressant effects. Shorter ITI stimulation protocols (4-10Ssinter-train intervals) activate GABA neurons, limiting resulting changes in cortical excitability and plasticity compared to extended interval TBS protocols (eTBS, with a 20s ITI). eTBS also drives the largest changes in synaptic / spine plasticity and leads to rapid and durable antidepressant-like effects after only a single stimulation session. Optogenetic activation of GABAergic neurons during eTBS blocks synaptic plasticity and rapid antidepressant effects. Together, these findings reveal a temporal control principle for TBS-induced cortical plasticity and provides a physiology-based strategy to improve TBS efficacy. HighlightsO_LIInter-train interval (ITI) controls excitatory-inhibitory balance during theta burst stimulation C_LIO_LIShort ITIs strongly activate PV interneurons limiting longer-term changes in glutamatergic excitatory plasticity C_LIO_LIExtended ITI (20s in particular) reduces inhibitory activity while maintaining sufficient activation of glutamatergic neurons to promote post-stimulation plasticity C_LIO_LIeTBS produces rapid and durable antidepressant-like effects that are blocked by GABAergic co-activation C_LI Graphical AbstractInter-train interval (ITI) determines the balance between excitation and inhibition during theta burst stimulation (TBS), an FDA-cleared treatment for depression. (A) Short ITIs (4s) drive concurrent glutamatergic and GABAergic activation, with inhibitory dominance during stimulation and suppressed long-term modulation of excitability. Extending the ITI to 20s (eTBS) reduces GABAergic recruitment during stimulation, promoting sustained long-term glutamatergic modulation resulting cortical disinhibition, leading to rapid and durable antidepressant-like effects (B). Optogenetic activation of GABAergic interneurons during eTBS abolishes synaptic and antidepressant effects, demonstrating that reduced inhibitory recruitment during eTBS is required for the rapid and durable behavioral effects observed with that protocol. O_FIG O_LINKSMALLFIG WIDTH=182 HEIGHT=200 SRC="FIGDIR/small/608693v3_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@15a7decorg.highwire.dtl.DTLVardef@1220forg.highwire.dtl.DTLVardef@63258forg.highwire.dtl.DTLVardef@13707e7_HPS_FORMAT_FIGEXP M_FIG C_FIG

Explore related subjects

neurosciencePreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Salimi, M., Nazari, M., Mishler, J., Mishra, J., Ramanathan, D.. 2024-08-20. Intermittent Theta Burst Stimulation Drives Bi-Directional Changes in Excitability in Prefrontal Cortex. https://doi.org/10.1101/2024.08.19.608693

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Different hippocampal subfield volumes predict source memory performance and general cognitive ability in an adult lifespan sample

Modest positive associations between episodic memory performance and whole hippocampal and hippocampal subfield volumes have been reported in numerous prior studies. A smaller number of studies have reported associations between hippocampal volume and performance on tests of non-mnemonic cognition. The present study examined whether these associations were evident in a lifespan sample of cognitively healthy adults. Of particular interest was whether any identified associations were sensitive to age, and whether associations between subfield volumes and mnemonic and non-mnemonic performance were subfield dependent. We acquired high-resolution T1- and T2-weighted structural images from 163 adults (18-87 years of age). Participants also undertook a comprehensive neuropsychological test battery and an in-scanner test of source memory. Principal components analysis was employed to reduce the neuropsychological test scores to 5 cognitive components. Two components reflected memory performance while the other three reflected different aspects of non-mnemonic cognition. Hippocampal subfields (Cornu Ammonis (CA)1, CA2-3, dentate gyrus (DG) and subiculum) were segmented and measured with the Automated Segmentation of Hippocampus Subfields (ASHS) package. Source memory performance was selectively associated across participants with CA2-3 volume. By contrast, both mnemonic and non-mnemonic component scores derived from the test battery were associated exclusively with the volume of the DG. All associations were age-invariant. The findings indicate that different cognitive domains can be dissociated by virtue of their associations with different hippocampal subfields. Of importance, these associations appear to be life-long and hence are unlikely to reflect individual differences in age-related decline in structural integrity.

neuroscience↗
bioRxiv2026

Cell type specific astrocytic feedback regulates excitation inhibition balance and cortical network dynamics

Astrocytes actively regulate synaptic transmission and neuronal excitability, yet their role in orchestrating macroscopic cortical network regimes and slow-wave oscillations remains an active area of reasearch. This study investigates how bidirectional neuron astrocyte interactions shape emergent population dynamics using a computational network model of excitatory and inhibitory neurons coupled to an astrocyte. The results identify astrocytic feedback topology, rather than astrocytic coupling strength alone, as a key determinant of emergent cortical network dynamics. By systematically dissecting pathway-specific connectivity, it has been shown that the neuronal population driving astrocytic activation and the neuronal population receiving gliotransmission jointly determine whether the network occupies asynchronous irregular (AI), synchronous irregular (SI), synchronous regular(SR), asynchronous regular(AR) or quiescent regimes.Directing gliotransmission selectively onto excitatory neurons consistently promotes population synchrony regardless of the population influencing astrocytic dynamics, whereas selective modulation of inhibitory interneurons induces network quiescence via strong suppression. Under dual-target gliotransmission, network synchrony is dictated by the population driving astrocytic dynamics: excitatory-only drive promotes synchrony, while combined or inhibitory-specific drive preserves asynchronous states. Furthermore, the model reveals that astrocytic signaling kinetics provide an additional temporal control mechanism that regulates the frequency and persistence of self sustained up states.

neuroscience↗
bioRxiv2026

VCP inhibition prevents cone photoreceptor degeneration in the cpfl1 mouse model of achromatopsia

Achromatopsia (ACHM) is a rare autosomal recessive retinal disorder characterized by absent cone photoreceptor function from early life, leading to severe visual impairment. Mutations in genes involved in the cone phototransduction cascade frequently result in elevated cyclic guanosine monophosphate (cGMP) levels and activation of stress pathways, including endoplasmic reticulum (ER) stress and the unfolded protein response. Targeting common downstream mechanisms rather than individual mutations may provide a broadly applicable therapeutic strategy. Here, we investigated whether pharmacological inhibition of valosin-containing protein (VCP), a key regulator of ER and protein homeostasis, can prevent cone degeneration in the spontaneous cone photoreceptor function loss 1 (cpfl1) mouse model of ACHM. Organotypic culture of retinal explants from cpfl1 mice were treated with the selective VCP inhibitor ML240. Cone survival, cell death, opsin expression and localization were assessed by TUNEL assay, immunohistochemistry, and quantitative image analysis. ML240 treatment significantly increased cone density and improved cone opsin expression and trafficking to the outer segments (OSs) in cpfl1 explants compared to controls. Importantly, rhodopsin trafficking in rod photoreceptors was unaffected, indicating that VCP inhibition did not impair normal rod phototransduction. These findings demonstrate that VCP inhibition by ML240 effectively preserves cone photoreceptors and improves cone-specific functional markers in the cpfl1 model. Targeting VCP may represent a mutation-independent therapeutic strategy for preventing cone death in ACHM.

neuroscience↗