Deep brain stimulation of the centromedian nucleus of the thalamus (CM-DBS) has emerged as a potential treatment for patients with drug-resistant epilepsy (DRE) (Fisher, 2023; Mithani et al., 2025; Suresh et al., 2024). In recent decades, CM-DBS has been increasingly used in patients with generalized DRE, including those with Lennox-Gastaut syndrome (LGS) (Shlobin et al., 2023; Agashe et al., 2022, Dalic et al., 2022). Although clinical studies have reported promising outcomes, response to treatment has been highly variable, and specific mechanisms underlying the anti-seizure effects of CM-DBS remain poorly understood (Gouveia et al., 2024). A critical gap in knowledge involves the effects of stimulation on neurotransmitter systems, which become impaired and play a key role in the pathogenesis of epilepsy (Sarlo and Holton, 2021; Akyuz et al., 2021). While prior studies have examined the neurochemical effects of CM stimulation, these have not been investigated in the context of epilepsy. Here, we performed CM-DBS in both healthy and epilepsy mouse models to study the effects of stimulation on glutamate and GABA, the primary excitatory and inhibitory neurotransmitters, respectively.

The anti-seizure effects of DBS for other targets have been associated with modulation of neurotransmitter systems (Matin et al., 2024; Covolan et al., 2024). In rodent models of epilepsy, DBS of the anterior nucleus of the thalamus has been associated with increased GABAergic, serotonergic, and adenosinergic signaling, along with reduced levels of glutamate in the hippocampus (Covolan et al., 2024; Ziai et al., 2005; Mirski et al., 2009; Miranda et al., 2014; Gimenes et al., 2022; Liu et al., 2012). Similarly, DBS targeting the hippocampal formation and amygdala have also been linked with enhanced local GABAergic signaling (Luna-Munguia et al., 2011; López-Meraz et al., 2004). These findings raise the possibility that the anti-epileptic effects of CM-DBS may also be mediated though neurochemical effects.

Although specific mechanisms underlying CM-DBS remain unclear, the therapeutic effects of stimulation are thought to involve the modulation of large-scale brain networks (Samanta et al., 2024; Warren et al., 2024; Ji et al., 2025). Notably, DBS of the lateral aspect of the CM, which primarily projects to the caudate and putamen, has been linked with beneficial outcomes, highlighting the dorsal striatum as a critical node (Mithani et al., 2025; Warren et al., 2022). Imaging studies have identified the thalamus and striatum as key components of generalized seizure networks and shown altered glutamate levels in both regions in patients with generalized epilepsy (Sarlo and Holton, 2021; Warren et al., 2022; Gotman and Pittau, 2011; Archer et al., 2014). Experimental studies in genetic rodent models of epilepsy have provided additional insights on the involvement of basal ganglia structures, demonstrating the influence of striatal activity on generalized epileptic discharges (Vuong and Devergnas, 2018; Depaulis and Charpier, 2018).

It is possible that CM-DBS exerts its anti-seizure effects, in part, by modulating striatal output. CM-striatal projections represent the primary non-cortical source of glutamatergic input to the striatum, and have been shown to modulate striatal output across various functions (Sadikot and Rymar, 2009; Smith et al., 2014). Additionally, experimentally manipulating CM output via electrical stimulation or pharmacological intervention has been shown to alter striatal neuronal firing and neurotransmitter levels (Consolo et al., 1996; Wilson et al., 1990; Zackheim and Abercrombie, 2005; Nanda et al., 2009). A stronger understanding of how CM-DBS influences neurotransmitter dynamics within this circuit could provide important mechanistic insight and guide strategies to improve clinical efficacy.

Beyond regional effects in the striatum, it is also important to consider how CM-DBS influences broader network-level interactions. Functional connectivity of basal ganglia circuits is altered in epilepsy, and emerging evidence suggests that neurotransmitter networks are also disrupted (Rektor et al., 2013; Luo et al., 2012; van Veenendaal et al., 2018). “Neurotransmitter networks” describe inter-regional correlations in neurotransmitter levels, offering a neurochemical perspective on how different regions are functionally coordinated (van Veenendaal et al., 2018). Patients with epilepsy show distinct alterations in these networks compared to healthy controls, particularly in correlations involving glutamate, GABA, and N-acetylaspartate (van Veenendaal et al., 2018; Hetherington et al., 2007; Pan et al., 2012). Notably, patients with epilepsy exhibit a greater number of regions with correlated glutamate and GABA levels, suggesting abnormal "neurochemical hypersynchrony" and a potential form of disrupted neurotransmitter dynamics (van Veenendaal et al., 2018). As DBS is thought to act on large-scale pathological networks, studying neurotransmitter effects from a network perspective may offer deeper insights into its mechanisms (Samanta et al., 2024; Warren et al., 2024; Ji et al., 2025).

In this study, we leveraged preclinical mouse models to investigate the neurochemical effects of CM-DBS. We used both healthy control mice (C57BL/6 J) and a genetic mouse model of generalized epilepsy (Cntnap2KO). In Cntnap2KO mice, homozygous knockout of the Cntnap2 gene results in disrupted glutamate and GABAergic neurotransmission within hippocampus, striatum, and cortex (Peñagarikano et al., 2011; Bridi et al., 2017; Thabault et al., 2024; Jurgensen and Castillo, 2015; Varea et al., 2015; Park et al., 2022; Del Rosario et al., 2021). These impairments are accompanied by generalized spike-wave-like discharges (SWDs), spontaneous seizures that emerge at approximately 6 months of age, and an array of behavioral impairments including nocturnal hypoactivity – reduced activity during typically active periods of the day (Peñagarikano et al., 2011; Thomas et al., 2017; Angelakos et al., 2019; Jankovic et al., 2019; Kolata et al., 2018; Robinson et al., 2013). We investigated how CM-DBS modulates striatal glutamate and GABA signaling and alters neurotransmitter network dynamics in both healthy and epilepsy model mice. This study focuses on acute neurochemical changes, rather than seizure frequency or behavioral outcomes, to provide foundational insight into how DBS may affect neurotransmitter systems relevant to epilepsy.