Publications by authors named "Gregory L. Holmes"

Objective: Neuropsychiatric comorbidities are prevalent in children with epilepsy and often pose greater concerns than the seizures themselves. Identifying children at risk for these conditions is crucial for developing effective therapies. In prepubescent rodents, sex significantly influences cognitive dysfunction related to seizures, with prepubescent male rats exhibiting more severe adverse effects than females.

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Background: Changes in brain connectivity during development are thought to reflect organizational and maturational processes that correspond to skill acquisition in domains like motor, language, and cognition. This theory is supported by findings in typically developing children as well as observations of abnormal connectivity among children with neurodevelopmental differences. However, few coherence studies have capitalized on the potential of sleep electroencephalogram (EEG) to examine the developing brain, especially among very young children for whom formal neurodevelopmental diagnosis is not yet possible.

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Article Synopsis
  • The National Vaccine Injury Compensation Program (VICP) was created in 1986 to provide compensation for vaccine-related injuries, with over $6 billion paid out since its inception, but claims related to postural orthostatic tachycardia syndrome (POTS) have never been thoroughly reviewed.
  • A study analyzed 102 cases involving POTS claims, examining petitioners' theories linking vaccines (especially the HPV vaccine) to POTS, as well as the responses from medical experts and the final compensation decisions by the court.
  • Results showed that while petitioners’ experts often suggested vaccines could cause POTS through autoimmunity, none of the cases found direct evidence linking vaccines to the condition, indicating a need to reassess the
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Objective: Sex determines cognitive outcome in animal models of early life seizure, where males exhibit impaired hippocampal-dependent learning and memory compared with females. The physiological underpinnings of this sex effect are unclear. Cholinergic signaling is essential for the generation of hippocampal oscillations, and supplementation of cholinergic precursors prior to status epilepticus in immature male rats prevents subsequent memory deficits.

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Background: Sleep plays a crucial role in early language development, and sleep disturbances are common in children with neurodevelopmental disorders. Examining sleep microarchitecture in toddlers with and without language delays can offer key insights into neurophysiological abnormalities associated with atypical neurodevelopmental trajectories and potentially aid in early detection and intervention.

Methods: Here, we investigated electroencephalogram (EEG) coherence and sleep spindles in 16 toddlers with language delay (LD) compared with a group of 39 typically developing (TD) toddlers.

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Obsessive compulsive disorder (OCD) is a comorbid condition of epilepsy and often adds to the burden of epilepsy. Both OCD and epilepsy are disorders of hyperexcitable circuits. Fronto-striatal circuit dysfunction is implicated in OCD.

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Gregory L. Holmes Seminars in Pediatric Neurology Volume 23, Issue 2, May 2016, Pages 120-126 Epilepsy is a complex disorder, which involves much more than seizures, encompassing a range of associated comorbid health conditions that can have significant health and quality-of-life implications. Of these comorbidities, cognitive impairment is one of the most common and distressing aspects of epilepsy.

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Objective: The National Childhood Vaccine Injury Act of 1986 created the National Vaccine Injury Compensation Program (VICP), a no-fault alternative to the traditional tort system. Since 1988, the total compensation paid exceeds $5 billion. Although epilepsy is one of the leading reasons for filing a claim, there has been no review of the process and validity of the legal outcomes given current medical information.

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Obsessive compulsive disorder (OCD) can occur comorbidly with epilepsy; both are complex, disruptive disorders that lower quality of life. Both OCD and epilepsy are disorders of hyperexcitable circuits, but it is unclear whether common circuit pathology may underlie the co-occurrence of these two neuropsychiatric disorders. Here, we induced early-life seizures (ELS) in rats to examine habit formation as a model for compulsive behaviors.

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How the development and function of neural circuits governing learning and memory are affected by insults in early life remains poorly understood. The goal of this study was to identify putative changes in cortico-hippocampal signaling mechanisms that could lead to learning and memory deficits in a clinically relevant developmental pathophysiological rodent model, Febrile status epilepticus (FSE). FSE in both pediatric cases and the experimental animal model, is associated with enduring physiological alterations of the hippocampal circuit and cognitive impairment.

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There is increasing human and animal evidence that brain oscillations play a critical role in the development of spatial cognition. In rat pups, disruption of hippocampal rhythms via optogenetic stimulation during the critical period for memory development impairs spatial cognition. Early-life seizures are associated with long-term deficits in spatial cognition and aberrant hippocampal oscillatory activity.

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θ-Scale coordination of prelimbic medial prefrontal cortex (mPFC) local field potentials (LFPs) and its influence via direct or indirect projections to the ventral hippocampus (vHC) and dorsal hippocampus (dHC) during spatial learning remains poorly understood. We hypothesized that θ frequency coordination dynamics within and between the mPFC, dHC, and vHC would be predetermined by the level of connectivity rather than reflecting differing circuit throughput relationships depending on cognitive demands. Moreover, we hypothesized that coherence levels would not change during learning of a complex spatial avoidance task.

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Background: Febrile seizures are the most common type of seizures in children. While in most children the outcome is favorable, children with febrile status epilepticus may exhibit modest cognitive impairment. Whether children with other forms of complex febrile seizure, such as repetitive febrile seizures within the same illness are at risk of cognitive deficits is not known.

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Objective: Febrile seizures (FSs) are the most common form of seizures in children. Single short FSs are benign, but FSs lasting longer than 30 min, termed febrile status epilepticus, may result in neurological sequelae. However, there is little information about an intermediary condition, brief recurrent FSs (RFSs).

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Introduction: Spinal anesthesia is utilized as an alternative to general anesthesia in infants for some surgeries. After spinal anesthesia, infants often become less conscious without administration of sedative medications. The aim of this study was to assess electroencephalographic (EEG) correlates after spinal anesthesia in a cohort of infants.

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Although interictal spikes (IISs) are a well-established EEG biomarker for epilepsy, whether they are also a biomarker of cognitive deficits is unclear. Interictal spikes are dynamic events consisting of a synchronous discharge of neurons producing high frequency oscillations and a succession of action potentials which disrupt the ongoing neural activity. There are robust data showing that IISs result in transitory cognitive impairment with the type of deficit specific to the cognitive task and anatomic location of the IIS.

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Objective: Early life seizures (ELSs) alter activity-dependent maturation of neuronal circuits underlying learning and memory. The pathophysiological mechanisms underpinning seizure-induced cognitive impairment are not fully understood, and critical variables such as sex and dynamic brain states with regard to cognitive outcomes have not been explored. We hypothesized that in comparison to control (CTL) rats, ELS rats would exhibit deficits in spatial cognition correlating with impaired dynamic neural signal coordination between the hippocampus and medial prefrontal cortex (mPFC).

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Cholinergic modulation of hippocampal network function is implicated in multiple behavioral and cognitive states. Activation of nicotinic and muscarinic acetylcholine receptors affects neuronal excitability, synaptic transmission and rhythmic oscillations in the hippocampus. In this work, we studied the ability of the cholinergic system to sustain hippocampal epileptiform activity independently from glutamate and GABA transmission.

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There is increasing recognition that epilepsy can be associated with a broad spectrum of comorbidities. While epileptic seizures are an essential element of epilepsy in children, there is a spectrum of neurological, mental health and cognitive disorders that add to the disease burden of childhood epilepsy resulting in a decreased quality of life. The most common comorbid conditions in childhood epilepsy include depression, anxiety, autism spectrum disorders, sleep disorders, attention deficits, cognitive impairment, and migraine.

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Objective: The objective of this study was to evaluate long-term safety and tolerability outcomes in two open-label extension (OLE) studies of adjunctive eslicarbazepine acetate (ESL) in children with focal seizures.

Methods: Safety data from patients aged 4-17 years in OLEs of Studies 2093-208 and -305 were pooled and analyzed. Studies 208 and 305 were randomized, double-blind, placebo-controlled studies of adjunctive treatment with ESL in children with focal seizures refractory to treatment with 1-2 antiseizure drugs; patients could continue into uncontrolled OLEs (up to 5 years total duration).

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Background: Hippocampal oscillations play a critical role in the ontogeny of allocentric memory in rodents. During the critical period for memory development, hippocampal theta is the driving force behind the temporal coordination of neuronal ensembles underpinning spatial memory. While known that hippocampal oscillations are necessary for normal spatial cognition, whether disrupted hippocampal oscillatory activity during the critical period impairs long-term spatial memory is unknown.

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Hippocampal theta oscillations show prominent changes in frequency and amplitude depending on behavioral state or cognitive demands. How these dynamic changes in theta oscillations contribute to the spatial and temporal organization of hippocampal cells, and ultimately behavior, remain unclear. We used low-theta frequency optogenetic stimulation to pace coordination of cellular and network activity between the medial septum (MS) and hippocampus during baseline and MS stimulation while rats were at rest or performing a spatial accuracy task with a visible or hidden goal zone.

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Cognitive deficits may arise from a variety of genetic alterations and neurological insults that impair neural coding mechanisms and the routing of neural information underpinning learning and memory. Slow and medium gamma oscillations underpin memory recall and sensorimotor processing and represent dynamic inputs at CA1 synapses. Febrile status epilepticus (FSE) can lead to increased risk for temporal lobe epilepsy and enduring cognitive impairments.

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