Monday, Jun 24: 5:45 PM - 7:00 PM
Oral Sessions
COEX
Room: Grand Ballroom 104-105
Presentations
Obsessive-compulsive disorder (OCD) is a clinically heterogeneous psychiatric disorder characterized by pathologically activated brain activity. Currently, first-line treatments for OCD fail to bring response in up to 60% of patients, indicating the refractory nature of OCD. Meanwhile, over 70% of the patients have only mild-to-moderate severity, their symptoms will develop into severe OCD without timely treatment, resulting in a greater burden on clinical treatment. Continuous theta burst stimulation (cTBS) can non-invasively induce inhibitory effects on the underlying cortex; hence, it is considered a potential treatment for inhibiting aberrantly hyperactivated brain regions in patients with obsessive-compulsive disorder (OCD). This is the first study to investigate the effectiveness of cTBS in the treatment of mild-to-moderate OCD in a preliminary study with an external validation design across two centers.
Presenter
Junjie Bu, Anhui Medical University Hefei, Anhui
China
Deep brain stimulation (DBS) in the anterior limb of the internal capsule (ALIC) for obsessive-compulsive disorder (OCD) can result in large improvements in symptoms and quality of life. However, without a clear stimulation target within the anatomically variable ALIC region, clinical benefits require long trial-and-error periods of parameter optimization.
We report an evolution toward precision ALIC DBS targeting for OCD based on patient-specific tractography. Our aim was to develop a targeting method that would result in a more uniform target location and symptom response pattern. We generated a responder common map of ALIC connectivity and used it to target a new cohort of patients prospectively. To validate our targeting method, we generated a tractography-based stimulation model to predict clinical outcomes.
The variability in the effects of transcranial Direct Current Stimulation (tDCS) is seen due to the inter-individual differences in brain anatomy causing variability in the current intensity reaching the Region of Interest (ROI). Evans et al. showed that variability in current intensity within the ROI can be reduced by varying the dose (amount of current applied to the scalp) from outside the brain [3]. It is known that current intensity at target ROI also depends on montage configurations like conventional (1x1) and high-definition (HD) tDCS (4x1) as HD-tDCS is thought to be more focal [1]. The present study investigates the variability in the personalised dose needed to obtain a constant intensity at the target ROI across individuals for both HD-tDCS and Conventional tDCS. This will be investigated in dementia patients, known to have severely atrophied brains, compared against a control major depressive disorder group expected to have relatively lesser brain atrophy.
Presenter
Irtisha Chakraborty, National institute of mental health and Neuro Sciences
Department of Neurophysiology
Bengaluru, Karnataka
India
The brain's spatiotemporal architecture, marked by functional connectivity motifs, is key to brain health and consciousness. Emerging theories highlight the thalamus' neuromodulatory role in shaping cortical connectivity motifs (Shine et al., 2023). However, testing these theories is challenging due to the small size, deep location and functional complexity of subcortical areas, where non-invasive neuroimaging techniques face limitations. In Stanford, we pioneered multi-site stimulation and recording in the thalamus using deep intracranial electrodes for mapping thalamic-centric causal connectivity. Thalamic stimulations are shown to evoke distinct EEG profiles than cortical stimulations from a recent mice study (Claar et al., 2023). Meanwhile, we have limited knowledge from direct human thalamic measurements. Therefore, our goal is to extract meaningful neural features from stimulation evoked potentials (SEP), then infer whole-brain causal connectivity.
Presenter
Dian Lyu, Stanford University
Neurology and Neurological Sciences
Palo Alto, CA
United States
The cortex of primate is organized by submillimeter functional domains. But little is known about how these coordinated units form a highly organized network on a brain-wide scale. Recently, the use of holographic optogenetics to target multiple brain areas opens up the possibility to modulate cortical information flow with diverse spatiotemporal patterns. Here we develop another patterned illumination method by infrared neural stimulation (INS), which is capable of producing a spatially focal stimulation via heat transients. This effective field is smaller than the column width in cat (~700µm). Combined with BOLD functional MRI in ultrahigh field, coordinated connectivity of the whole-brain can be mapped and further manipulated with patterns.
Presenter
Yipeng Liu, Zhejiang University Hangzhou, Hangzhou
China
Resting-state (RS) fMRI is a potent tool for mapping brain-wide functional connectivity (FC), yet its mechanism remains not fully understood. RS FC only partially corresponds to monosynaptic structural connectivity (SC) while exhibiting strong interhemispheric connections, implicating polysynaptic or indirect connectivity (Honey et al. 2009, Grandjean et al. 2017). However, a causal link between spontaneous neural interactions and FC has yet to be established. Optogenetic fMRI may resolve this question by mapping changes in neural activity induced by precise spatiotemporal neural manipulation (effective connectivity; EC). Notably, optogenetic activation of local excitatory neurons revealed predominantly ipsilateral connections resembling SC (Bauer et al. 2018, Kim et al. 2023). We hypothesized that this discrepancy arises because the upregulation of neural activity does not account for spontaneously occurring connectivity. To address this, we employed optogenetic silencing to assess ongoing interactions during RS. Our study investigated (de)activation patterns resulting from excitatory and inhibitory neuron-specific optogenetic EC and their relationship with SC and FC (Figure 1A).
Presenter
Hyun Seok Moon, Center for Neuroscience Imaging Research, Institute of Basic Science Suwon, Gyeonggi-do
Korea, Republic of