Hippocampal interneuronal dysfunction and hyperexcitability in a porcine model of concussion.

Cognitive impairment is a common symptom following mild traumatic brain injury (mTBI or concussion) and can persist for years in some individuals. Hippocampal slice preparations following closed-head, rotational acceleration injury in swine have previously demonstrated reduced axonal function and hippocampal circuitry disruption. However, electrophysiological changes in hippocampal neurons and their subtypes in a large animal mTBI model have not been examined.

Traumatic Brain Injury Preserves Firing Rates But Disrupts Laminar Oscillatory Coupling and Neuronal Entrainment in Hippocampal CA1.

While hippocampal-dependent learning and memory are particularly vulnerable to traumatic brain injury (TBI), the functional status of individual hippocampal neurons and their interactions with oscillations are unknown following injury. Using the most common rodent TBI model and laminar recordings in CA1, we found a significant reduction in oscillatory input into the radiatum layer of CA1 after TBI. Surprisingly, CA1 neurons maintained normal firing rates despite attenuated input, but did not maintain appropriate synchronization with this oscillatory input or with local high-frequency oscillations.

Multichannel Silicon Probes for Awake Hippocampal Recordings in Large Animals.

Decoding laminar information across deep brain structures and cortical regions is necessary in order to understand the neuronal ensembles that represent cognition and memory. Large animal models are essential for translational research due to their gyrencephalic neuroanatomy and significant white matter composition. A lack of long-length probes with appropriate stiffness allowing penetration to deeper structures with minimal damage to the neural interface is one of the major technical limitations to applying the approaches currently utilized in lower order animals to large animals.

Electrophysiological Signature Reveals Laminar Structure of the Porcine Hippocampus.

The hippocampus is integral to working and episodic memory and is a central region of interest in diseases affecting these processes. Pig models are widely used in translational research and may provide an excellent bridge between rodents and nonhuman primates for CNS disease models because of their gyrencephalic neuroanatomy and significant white matter composition. However, the laminar structure of the pig hippocampus has not been well characterized.

Rotational vertebrobasilar insufficiency due to compression of a persistent first intersegmental vertebral artery variant: case report.

Rotational vertebrobasilar insufficiency, or bow hunter's syndrome, is a rare cause of posterior circulation ischemia, which, following rotation of the head, results in episodic vertigo, dizziness, nystagmus, or syncope. While typically caused by dynamic occlusion of the vertebral artery in its V and V segments, the authors here describe a patient with dynamic occlusion of the vertebral artery secondary to a persistent first intersegmental artery, a rare variant course of the vertebral artery. In this case the vertebral artery coursed under rather than over the posterior arch of the C-1.

Disruption of Network Synchrony and Cognitive Dysfunction After Traumatic Brain Injury.

Traumatic brain injury (TBI) is a heterogeneous disorder with many factors contributing to a spectrum of severity, leading to cognitive dysfunction that may last for many years after injury. Injury to axons in the white matter, which are preferentially vulnerable to biomechanical forces, is prevalent in many TBIs. Unlike focal injury to a discrete brain region, axonal injury is fundamentally an injury to the substrate by which networks of the brain communicate with one another.

Reading, hearing, and the planum temporale.

Many neuroimaging studies of single-word reading have been carried out over the last 15 years, and a consensus as to the brain regions relevant to this task has emerged. Surprisingly, the planum temporale (PT) does not appear among the catalog of consistently active regions in these investigations. Recently, however, several studies have offered evidence suggesting that the left posteromedial PT plays a role in both speech production and speech perception.