Comparison of extracellular Giant depolarizing potentials in vitro and early sharp waves in vivo in the CA1 hippocampus of neonatal rats.

Giant Depolarizing Potentials (GDPs) and Early Sharp Waves (eSPWs) are the major patterns of neuronal network activity in the developing hippocampus of neonatal rodents in vitro and in vivo, respectively. Because of certain similarities in their electrographic traits, GDPs and eSPWs were originally considered as homologous patterns. Here, we compared electrographic features and current density profiles of field GDPs (fGDPs) and eSPWs using extracellular multisite silicon probe recordings from neonatal rat CA1 hippocampus.

Synchronous excitation in the superficial and deep layers of the medial entorhinal cortex precedes early sharp waves in the neonatal rat hippocampus.

Early Sharp Waves (eSPWs) are the earliest pattern of network activity in the developing hippocampus of neonatal rodents. eSPWs were originally considered to be an immature prototype of adult SPWs, which are spontaneous top-down hippocampal events that are self-generated in the hippocampal circuitry. However, recent studies have shifted this paradigm to a bottom-up model of eSPW genesis, in which eSPWs are primarily driven by the inputs from the layers 2/3 of the medial entorhinal cortex (MEC).

Diversity of cortical activity changes beyond depression during Spreading Depolarizations.

Spreading depolarizations (SDs) are classically thought to be associated with spreading depression of cortical activity. Here, we found that SDs in patients with subarachnoid hemorrhage produce variable, ranging from depression to booming, changes in electrocorticographic activity, especially in the delta frequency band. In rats, depression of activity was characteristic of high-potassium-induced full SDs, whereas partial superficial SDs caused either little change or a boom of activity at the cortical vertex, supported by volume conduction of signals from spared delta generators in the deep cortical layers.

Synaptic Origin of Early Sensory-evoked Oscillations in the Immature Thalamus.

During the critical period of postnatal development, brain maturation is extremely sensitive to external stimuli. Newborn rodents already have functional somatosensory pathways and the thalamus, but the cortex is still forming. Immature thalamic synapses may produce large postsynaptic potentials in immature neurons, while non-synaptic membrane currents remain relatively weak and slow.

Molecular and Cellular Mechanisms of Epilepsy.

Despite the availability of a large number of antiepileptic drugs, about 30% of patients with epilepsy, especially temporal lobe epilepsy (TLE), continue to experience seizures [...