A roadmap for SHANK3-related Epilepsy Research: recommendations from the 2023 strategic planning workshop.

On September 27, 2023, the CureSHANK nonprofit foundation sponsored a conference in Boston, Massachusetts, to identify gaps in knowledge surrounding SHANK3-related epilepsy with the goal of determining future research priorities and recommendations. In addition to patient families and members of the CureSHANK community, participants in the conference included a broad cross-section of preclinical and clinical researchers and clinicians with expertise in SHANK3-related epilepsy as well as representatives from the pharmaceutical industry. Here we summarize the outcomes from comprehensive premeeting deliberations and the final conference recommendations, including (1) gaps in knowledge related to clinical science, (2) gaps in knowledge related to preclinical science, and (3) research priorities moving forward.

Optimized ultrasound neuromodulation for non-invasive control of behavior and physiology.

Focused ultrasound can non-invasively modulate neural activity, but whether effective stimulation parameters generalize across brain regions and cell types remains unknown. We used focused ultrasound coupled with fiber photometry to identify optimal neuromodulation parameters for four different arousal centers of the brain in an effort to yield overt changes in behavior. Applying coordinate descent, we found that optimal parameters for excitation or inhibition are highly distinct, the effects of which are generally conserved across brain regions and cell types.

The fasciola cinereum of the hippocampal tail as an interventional target in epilepsy.

Targeted tissue ablation involving the anterior hippocampus is the standard of care for patients with drug-resistant mesial temporal lobe epilepsy. However, a substantial proportion continues to suffer from seizures even after surgery. We identified the fasciola cinereum (FC) neurons of the posterior hippocampal tail as an important seizure node in both mice and humans with epilepsy.

Neural and behavioural state switching during hippocampal dentate spikes.

Distinct brain and behavioural states are associated with organized neural population dynamics that are thought to serve specific cognitive functions. Memory replay events, for example, occur during synchronous population events called sharp-wave ripples in the hippocampus while mice are in an 'offline' behavioural state, enabling cognitive mechanisms such as memory consolidation and planning. But how does the brain re-engage with the external world during this behavioural state and permit access to current sensory information or promote new memory formation? Here we found that the hippocampal dentate spike, an understudied population event that frequently occurs between sharp-wave ripples, may underlie such a mechanism.

Retrograde endocannabinoid signaling at inhibitory synapses in vivo.

Endocannabinoid (eCB)-mediated suppression of inhibitory synapses has been hypothesized, but this has not yet been demonstrated to occur in vivo because of the difficulty in tracking eCB dynamics and synaptic plasticity during behavior. In mice navigating a linear track, we observed location-specific eCB signaling in hippocampal CA1 place cells, and this was detected both in the postsynaptic membrane and the presynaptic inhibitory axons. All-optical in vivo investigation of synaptic responses revealed that postsynaptic depolarization was followed by a suppression of inhibitory synaptic potentials.

Acetylcholine receptor based chemogenetics engineered for neuronal inhibition and seizure control assessed in mice.

Epilepsy is a prevalent disorder involving neuronal network hyperexcitability, yet existing therapeutic strategies often fail to provide optimal patient outcomes. Chemogenetic approaches, where exogenous receptors are expressed in defined brain areas and specifically activated by selective agonists, are appealing methods to constrain overactive neuronal activity. We developed BARNI (Bradanicline- and Acetylcholine-activated Receptor for Neuronal Inhibition), an engineered channel comprised of the α7 nicotinic acetylcholine receptor ligand-binding domain coupled to an α1 glycine receptor anion pore domain.

Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia.

Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments.

A tool for monitoring cell type-specific focused ultrasound neuromodulation and control of chronic epilepsy.

Focused ultrasound (FUS) is a powerful tool for noninvasive modulation of deep brain activity with promising therapeutic potential for refractory epilepsy; however, tools for examining FUS effects on specific cell types within the deep brain do not yet exist. Consequently, how cell types within heterogeneous networks can be modulated and whether parameters can be identified to bias these networks in the context of complex behaviors remains unknown. To address this, we developed a fiber Photometry Coupled focused Ultrasound System (PhoCUS) for simultaneously monitoring FUS effects on neural activity of subcortical genetically targeted cell types in freely behaving animals.

A consensus statement on detection of hippocampal sharp wave ripples and differentiation from other fast oscillations.

Decades of rodent research have established the role of hippocampal sharp wave ripples (SPW-Rs) in consolidating and guiding experience. More recently, intracranial recordings in humans have suggested their role in episodic and semantic memory. Yet, common standards for recording, detection, and reporting do not exist.

Is it the Sermon or the Choir? Pastoral Support, Congregant Support, and Worshiper Mental Health.

Background: Although religious involvement tends to be associated with improved mental health, additional work is needed to identify the specific aspects of religious practice that are associated with positive mental health outcomes. Our study advances the literature by investigating how two unique forms of religious social support are associated with mental health.

Purpose: We explore whether support received in religious settings from fellow congregants or religious leaders is associated with participants' mental health.

Ripple-selective GABAergic projection cells in the hippocampus.

Ripples are brief high-frequency electrographic events with important roles in episodic memory. However, the in vivo circuit mechanisms coordinating ripple-related activity among local and distant neuronal ensembles are not well understood. Here, we define key characteristics of a long-distance projecting GABAergic cell group in the mouse hippocampus that selectively exhibits high-frequency firing during ripples while staying largely silent during theta-associated states when most other GABAergic cells are active.

Supramammillary regulation of locomotion and hippocampal activity.

Locomotor speed is a basic input used to calculate one’s position, but where this signal comes from is unclear. We identified neurons in the supramammillary nucleus (SuM) of the rodent hypothalamus that were highly correlated with future locomotor speed and reliably drove locomotion when activated. Robust locomotion control was specifically identified in (substance P)–expressing (SuM) neurons, the activation of which selectively controlled the activity of speed-modulated hippocampal neurons.

A fluorescent sensor for spatiotemporally resolved imaging of endocannabinoid dynamics in vivo.

Endocannabinoids (eCBs) are retrograde neuromodulators with important functions in a wide range of physiological processes, but their in vivo dynamics remain largely uncharacterized. Here we developed a genetically encoded eCB sensor called GRAB. GRAB consists of a circular-permutated EGFP and the human CB1 cannabinoid receptor, providing cell membrane trafficking, second-resolution kinetics with high specificity for eCBs, and shows a robust fluorescence response at physiological eCB concentrations.

In vivo endocannabinoid dynamics at the timescale of physiological and pathological neural activity.

The brain's endocannabinoid system is a powerful controller of neurotransmitter release, shaping synaptic communication under physiological and pathological conditions. However, our understanding of endocannabinoid signaling in vivo is limited by the inability to measure their changes at timescales commensurate with the high lability of lipid signals, leaving fundamental questions of whether, how, and which endocannabinoids fluctuate with neural activity unresolved. Using novel imaging approaches in awake behaving mice, we now demonstrate that the endocannabinoid 2-arachidonoylglycerol, not anandamide, is dynamically coupled to hippocampal neural activity with high spatiotemporal specificity.

Alternating sources of perisomatic inhibition during behavior.

Interneurons expressing cholecystokinin (CCK) and parvalbumin (PV) constitute two key GABAergic controllers of hippocampal pyramidal cell output. Although the temporally precise and millisecond-scale inhibitory regulation of neuronal ensembles delivered by PV interneurons is well established, the in vivo recruitment patterns of CCK-expressing basket cell (BC) populations has remained unknown. We show in the CA1 of the mouse hippocampus that the activity of CCK BCs inversely scales with both PV and pyramidal cell activity at the behaviorally relevant timescales of seconds.

In vivo assessment of mechanisms underlying the neurovascular basis of postictal amnesia.

Long-lasting confusion and memory difficulties during the postictal state remain a major unmet problem in epilepsy that lacks pathophysiological explanation and treatment. We previously identified that long-lasting periods of severe postictal hypoperfusion/hypoxia, not seizures per se, are associated with memory impairment after temporal lobe seizures. While this observation suggests a key pathophysiological role for insufficient energy delivery, it is unclear how the networks that underlie episodic memory respond to vascular constraints that ultimately give rise to amnesia.

Quantitative T MRI is predictive of neurodegeneration following organophosphate exposure in a rat model.

Organophosphorus compounds, such as chemical warfare nerve agents and pesticides, are known to cause neurological damage. This study measured nerve agent-related neuropathology and determined whether quantitative T MRI could be used as a biomarker of neurodegeneration. Quantitative T MRI was performed using a 9.

Dynamic oxygen changes during status epilepticus and subsequent endogenous kindling.

Objective: Brain tissue oxygen (partial oxygen pressure [pO ]) levels are tightly regulated to stay within the normoxic zone, with deviations on either side resulting in impaired brain function. Whereas pathological events such as ischemic attacks and brief seizures have previously been shown to result in pO levels well below the normoxic zone, oxygen levels during prolonged status epilepticus (SE) and the subsequent endogenous kindling period are unknown.

Methods: We utilized two models of acquired temporal lobe epilepsy in rats: intrahippocampal kainic acid infusion and prolonged perforant pathway stimulation.

Resolving the Micro-Macro Disconnect to Address Core Features of Seizure Networks.

Current drug treatments for epilepsy attempt to broadly restrict excitability to mask a symptom, seizures, with little regard for the heterogeneous mechanisms that underlie disease manifestation across individuals. Here, we discuss the need for a more complete view of epilepsy, outlining how key features at the cellular and microcircuit level can significantly impact disease mechanisms that are not captured by the most common methodology to study epilepsy, electroencephalography (EEG). We highlight how major advances in neuroscience tool development now enable multi-scale investigation of fundamental questions to resolve the currently controversial understanding of seizure networks.

Plants come to mind: phytocannabinoids, endocannabinoids and the control of seizures.

A growing body of evidence highlights that the endogenous cannabinoid (endocannabinoid) system is a key target for seizure control. Plant-derived cannabinoids have several endocannabinoid and related mechanisms that may be fundamental to their anti-seizure properties.

Fast oxygen dynamics as a potential biomarker for epilepsy.

Changes in brain activity can entrain cerebrovascular dynamics, though this has not been extensively investigated in pathophysiology. We assessed whether pathological network activation (i.e.

Neurodegeneration and Pathology in Epilepsy: Clinical and Basic Perspectives.

Epilepsy is commonly associated with a number of neurodegenerative and pathological alterations in those areas of the brain that are involved in repeated electrographic seizures. These most prominently include neuron loss and an increase in astrocyte number and size but may also include enhanced blood-brain barrier permeability, the formation of new capillaries, axonal sprouting, and central inflammation. In animal models in which seizures are either repeatedly elicited or are self-generated, a similar set of neurodegenerative and pathological alterations in brain anatomy are observed.

Postictal hypoperfusion/hypoxia provides the foundation for a unified theory of seizure-induced brain abnormalities and behavioral dysfunction.

A recent article by Farrell et al. characterizes the phenomenon, mechanisms, and treatment of a local and severe hypoperfusion/hypoxia event that occurs in brain regions following a focal seizure. Given the well-established role of cerebral ischemia/hypoxia in brain damage and behavioral dysfunction in other clinical settings (e.

Postictal behavioural impairments are due to a severe prolonged hypoperfusion/hypoxia event that is COX-2 dependent.

Seizures are often followed by sensory, cognitive or motor impairments during the postictal phase that show striking similarity to transient hypoxic/ischemic attacks. Here we show that seizures result in a severe hypoxic attack confined to the postictal period. We measured brain oxygenation in localized areas from freely-moving rodents and discovered a severe hypoxic event (pO < 10 mmHg) after the termination of seizures.

HCN channels segregate stimulation-evoked movement responses in neocortex and allow for coordinated forelimb movements in rodents.

Key Points: The present study tested whether HCN channels contribute to the organization of motor cortex and to skilled motor behaviour during a forelimb reaching task. Experimental reductions in HCN channel signalling increase the representation of complex multiple forelimb movements in motor cortex as assessed by intracortical microstimulation. Global HCN1 mice exhibit reduced reaching accuracy and atypical movements during a single-pellet reaching task relative to wild-type controls.