Biology subjects

Sachse, E. M.

Publications and source records attributed to Sachse, E. M..

6 recordsLinked to original sources

bioRxiv2026

Prefrontal cortical pathways mediating cognitive control enhancement from internal capsule stimulation

BackgroundDeep brain stimulation (DBS) targeting the ventral internal capsule/ventral striatum (VCVS) is an effective treatment for several psychiatric disorders, but clinical responses often vary amongst patients likely due to an incomplete mechanistic understanding of the brain pathways mediating response. VCVS DBS can improve cognitive control, a core deficit in multiple psychiatric disorders. Here, we investigated which prefrontal cortical pathway(s) in the internal capsule are associated with improving cognitive control during VCVS DBS. MethodsFour participants with bilateral VCVS DBS completed the Multi-Source Interference Task (MSIT) under 27 stimulation settings varying by side (left/right lead), electrode, amplitude, and frequency. Each condition included 100 trials and response time (RT) assessed task performance. Personalized pathway activation models quantified axonal recruitment across 11 segmented prefrontal cortical fiber bundles per brain hemisphere. Associations between pathway activation and task RT were analyzed to identify circuits linked to improved cognitive control performance. ResultsRight-sided VCVS stimulation produced greater improvements in cognitive control (reductions in MSIT RT) than left-sided stimulation. Activation of right dorsal prefrontal cortical pathways connected to the dorsolateral prefrontal cortex (dlPFC) and dorsomedial prefrontal cortex (dmPFC) most strongly predicted faster MSIT RTs, whereas no left-sided pathways were associated with performance changes. ConclusionsThese findings suggest that the effects of VCVS DBS on cognitive control are primarily mediated by right dorsal prefrontal cortical axons projecting from the dlPFC and dmPFC. Targeting these pathways may improve stimulation strategies and outcomes for psychiatric disorders characterized by impaired cognitive control.

neuroscience↗

bioRxiv2026

mPFC axons drive cognitive control enhancement during striatal stimulation

Deep brain stimulation (DBS) of the ventral internal capsule/ventral striatum (VCVS) can alleviate symptoms of mental illness and may work in part by improving cognitive control, a feature of healthy decision making. The human VCVS DBS target and its mid-striatum analog in our preclinical rodent model contain both cortical axons and local striatal cell bodies. However, the specific neural components that stimulation acts on to mediate cognitive effects remain unclear. We addressed this by delivering high frequency optogenetic stimulation ("opto-DBS") to either medial prefrontal cortex (mPFC) axons or local mid-striatal (midSTR) neurons in a rodent Set-Shift task. Opto-DBS of mPFC axons reduced response times, effectively replicating the cognitive enhancement observed in a previous study that used electrical stimulation. Conversely, we observed cognitive impairment from sustained (>10 min) opto-DBS of midSTR neurons. In addition, the cognitive benefit from axonal opto-DBS exhibited time-dependent declines that were not observed with electrical stimulation. The improvement in response times declined within a session and was associated with attenuated magnitude of local midSTR evoked-response potentials. Across-testing days, we linked this decline to diminished mPFC responsiveness, evidenced by a reduction in the post-DBS functional strength of the circuit, suggesting a neuroplastic-like mechanism. These results demonstrate that mPFC-originating axons, rather than local neurons, are the primary drivers of cognitive control enhancements from electrical stimulation, providing insight into therapeutic mechanisms of VCVS DBS.

neuroscience↗

bioRxiv2025

Real-time Bayesian optimization of deep brain stimulation for personalized cognitive control enhancement

BackgroundIdentifying effective deep brain stimulation (DBS) parameters for psychiatric disorders has historically been a time-consuming and error prone process due to a lack of an objective and rapid readout of target circuit engagement. Cognitive control may have use as a biomarker of treatment efficacy but it has yet to be shown that DBS parameters can be reliably optimized to produce cognitive control improvements in individual subjects. ObjectiveWe sought to leverage a rat model of DBS-driven cognitive control improvements to determine whether state of the art optimization algorithms could consistently identify effective stimulation amplitudes to enhance cognition. MethodsWe delivered periods of active and inactive DBS-like stimulation at variable parameters while rats performed a Set-Shifting task that we previously showed to be stimulation-sensitive. We tested both predefined settings of interest and settings that were personalized to individual animals using Bayesian Optimization. Measurements of task performance including reaction time and accuracy were compared between acute, optimized, and traditional settings to evaluate effects on cognitive control. ResultsAcute stimulation reduced reaction times without hindering accuracy (N=15), replicating the effects previously observed with chronic stimulation. In a second cohort (N=6), optimization of stimulation amplitude successfully reduced reaction times in all animals with comparable effect size to historically best settings. ConclusionThese findings confirm that optimization techniques can be effective for improving symptomatically-relevant cognitive markers supporting the feasibility of personalized, quantitatively-informed approaches to neuromodulation and target engagement for psychiatric and/or cognitive disorders. HighlightsProving target engagement is a substantial challenge across brain stimulation modalities, and objective, rapid behavioral read-outs may be a solution to that challenge. Reaction times in cognitive control tasks are an example of a behavioral measure that changes rapidly in response to changes in stimulation parameters, and that also may predict clinical outcomes. Individually optimal stimulation amplitudes for reducing reaction time by stimulating corticofugal fibers passing through the striatum can be determined using Bayesian Optimization. Individually optimized settings discovered in an acute preparation demonstrate consistent effects when applied chronically.

neuroscience↗

bioRxiv2025

Unilateral striatal deep brain stimulation improves cognitive control

Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VCVS) can treat obsessive-compulsive disorder (OCD) and other psychiatric conditions. Yet, optimizing its clinical efficacy is a major challenge, often hindered by incomplete knowledge of how stimulation parameters and targets affect neural activity and behavior. VCVS DBS is thought to work in part by improving cognitive control, an important decision-making component that is impaired in OCD and other illnesses. The magnitude of this cognitive control enhancement was shown to be lateralized, with right-unilateral stimulation being the most effective. Prior work developed a preclinical model of VCVS DBS by leveraging the cognitive control construct, which can be measured in humans and rodents and is modulated by analogous brain circuits. However, this work did not address laterality effects observed in humans or examine left/right stimulation differences. These effects may be critical for maximizing therapeutic benefit while avoiding aversive outcomes. This study aimed to investigate lateralization in the rodent model, where bilateral stimulation of the mid-striatum was previously shown to improve cognitive control. Right and left-unilateral stimulation reduced response times without changing accuracy, replicating the cognitive control improvement from bilateral stimulation. With computational modeling, we show that bilateral and unilateral stimulation modifies the same decision-making variables to drive this behavior change. We also establish that females have the same cognitive control improvement from stimulation as males. These findings increase our understanding of cognitive control circuits and strengthen the validity of the rodent model as a translational platform to study VCVS DBSs therapeutic mechanisms. Significance StatementHere, we demonstrate that stimulating just one side of the brain (e.g. unilaterally) can be as effective as bilateral stimulation for improving cognitive control, the ability to adjust thoughts and decisions in response to environmental changes. These findings in rodents match results from prior human deep brain stimulation (DBS) studies, highlighting the validity of this preclinical model to study DBSs therapeutic mechanisms. We hypothesize that unilateral stimulation may be preferable to maximize cognitive benefits without causing off-target effects, while also reducing surgical invasiveness. Further, we demonstrate that females have the same cognitive control improvement from stimulation as males. Overall, this work answers important outstanding clinical questions regarding laterality and sex in DBS therapies for psychiatric illnesses.

neuroscience↗

bioRxiv2024

Cross-species modeling and enhancement of cognitive control with striatal brain stimulation

Brain disorders, particularly mental disorders, might be effectively treated by direct electrical brain stimulation, but clinical progress requires understanding of therapeutic mechanisms. Animal models have not helped, because there are no direct animal models of mental illness. We show a path past this roadblock, by leveraging a common ingredient of most mental disorders: impaired cognitive control. We previously showed that deep brain stimulation (DBS) improves cognitive control in humans. We now reverse translate that result, showing that DBS-like stimulation of the mid-striatum improves cognitive control in rats. Using this model, we identify a mechanism, improvement in domain-general cognitive control, and rule out competing hypotheses such as impulsivity. The rat findings explain prior human results and have immediate implications for clinical practice and future trial design. One Sentence Summary: Developing a reliable animal model of a human brain stimulation therapy reveals that this therapy works by enhancing the brains ability to process conflicting pieces of evidence.

neuroscience↗

bioRxiv2022

Dynamic attention signaling in V4: relation to excitatory/inhibitory cell class and population coupling

Neurons have different roles in attention processing. These roles are determined by a neurons firing properties, neurotransmitter expression, and functional connectivity. Neurons in the visual cortical area, V4, are reliably engaged by selective attention but exhibit differences in firing rate and correlated variability. It remains unclear what specific neuronal properties shape these attention effects. We identified neurons as fast-spiking (FS) (putative inhibitory) and regular-spiking (RS) (putative excitatory) and investigated their role in anticipatory attention and how this related to their functional connectivity. V4 neurons exhibited a continuum of time-varying attention effects ranging from "restless-weak" neurons at one extreme to "quiet-strong" neurons at another. We found an interdependence between neural attention effects (e.g., restless-weak or quiet-strong), neuron type (FS, RS), and functional connectivity. In particular, we found neurons with restless-weak attention effects were more likely to be RS and have greater population coupling, compared to neurons with other types of attention effects. Also, quiet-strong neurons were more likely to be FS and these FS neurons exhibited higher spike synchrony. From this we propose that time-varying attention effects in a neuronal population depends on the relative involvement of neurons that drive stimulus processing and those that are engaged by intrinsic population activity. These results add important information to our understanding of visual attention circuits at the cellular level.

neuroscience↗