THE EFFECT of exciting motor cortical areas is usually studied by recording muscle contractions or observing limb movements. Such studies yield little information about the central excitatory events which ultimately funnel into the final common motor pathway. Adrian and Moruzzi (1) were the first to recognize the importance of recording activity in the pyramidal tract. Their results were signif...

Transient cerebral ischemia kills CA1 pyramidal cells of the hippocampus, whereas most CA1 interneurons survive. It has been proposed that calcium-binding proteins, neurotrophins, and/or inhibitory neuropeptides protect interneurons from ischemia. However, different synaptic responses early after reperfusion could also underlie the relative vulnerabilities to ischemia of pyramidal cells and int...

Recent behavioral studies indicate that conditioned fear response to contextual stimuli is reduced effectively by anxiolytic 5-hydroxytryptame (5-HT)1A agonists. Since the hippocampus seems to play an essential role in associative fear memories evoked by context, it is important to assess the effect of 5-HT1A agonists on pyramidal cell activity in the hippocampus. We examined the effects of 5-H...

While the synaptic mechanisms involved in the generation of in vitro network oscillations have been widely studied, little is known about the importance of voltage-gated currents during such activity. Here we study the role of the M-current (I(M)) in the modulation of network oscillations in the gamma-frequency range (20-80 Hz). Kv7/KCNQ subunits, the molecular correlates of I(M), are abundantl...

KCNQ2 and KCNQ3 potassium channels have emerged as central regulators of pyramidal neuron excitability and spiking behavior. However, despite an abundance of evidence demonstrating that KCNQ2/3 heteromers underlie critical potassium conductances, it is unknown whether KCNQ2, KCNQ3, or both are obligatory for maintaining normal pyramidal neuron excitability. Here, we demonstrate that conditional...

The neonatal period is critical for seizure susceptibility, and neocortical networks are central in infantile epilepsies. We report that application of 4-aminopyridine (4-AP) to immature (P6-P9) neocortical slices generates layer-specific interictal seizures (IISs) that transform after recurrent seizures to ictal seizures (ISs). During IISs, cell-attached recordings show action potentials in in...

The predominant excitatory synaptic input to the hippocampus arises from entorhinal cortical axons that synapse with dentate granule cells, which in turn synapse with CA3 pyramidal cells. Thus two highly excitable brain areas--the entorhinal cortex and the CA3 field--are separated by dentate granule cells, which have been proposed to function as a gate or filter. However, unlike rats, primates ...

Stochastic resonance (SR) in a hippocampal network model was investigated. The hippocampal model consists of two layers, CA3 and CA1. Pyramidal cells in CA3 are connected to pyramidal cells in CA1 through Schaffer collateral synapses. The CA3 network causes spontaneous irregular activity (broadband spectrum peaking at around 3 Hz), while the CA1 network does not. The activity of CA3 causes memb...

A pyramidal lobe of the thyroid gland is a common anatomic variant. However, primary malignancy of the pyramidal lobe is rare with the exception of cancer in a thyroglossal duct cyst. A 61-year-old morbidly obese woman presented with a 30 lb. weight loss and a large asymptomatic submental neck mass that extended to the base of her tongue. The mass was invading the hyoid bone and the sternohyoid...

We investigated the effects of repeated early-life seizures induced by flurothyl inhalation on intrinsic membrane properties of hippocampal pyramidal neurons from young rats (postnatal day 15-20). Intracellular recordings of CA1 and CA3 pyramidal neurons from flurothyl-treated and control rats revealed no significant differences in resting membrane potential, input resistance, membrane time con...