Not all synapses in the brain are the same. Some transmit signals from one neuron to the next more efficiently than others; the efficiency is referred to as synaptic strength. Currently the most widely accepted theory of memory is that memories are stored as patterns of synaptic strength. Longterm potentiation (LTP) is one way that the strength of synapses is changed and perhaps memories are en...

John Sarvey and his collaborators made major contributions to our understanding of the noradrenergic contribution to plasticity in the dentate gyrus of the hippocampus. The present chapter considers, first, the conclusions reached using in vitro models, and is based primarily on the work of John Sarvey and his collaborators, and, then, describes in vivo data and the interrelationships between t...

Opioid peptides costored with glutamate have emerged as powerful regulators of long-term potentiation (LTP) induction in several hippocampal pathways. The objectives of the present study were twofold: (1) to identify which opioid receptor types (mu, delta, or kappa) regulate LTP induction at lateral perforant path-granule cell synapses and (2) to test the hypothesis that endogenous opioids regu...

Introduction: Low-frequency stimulation (LFS) has a delaying effect on kindled seizures acquisition. In the present study we examined the role of galanin receptors in the inhibitory effects of LFS on kindled seizures induced by electrical stimulation of perforant path. Methods: Animals were stimulated daily at the AD threshold intensity with a rapid kindling procedure. LFS was applied immed...

The reaction of microglial and a stroglial cells to anterograde axonal degeneration was studied in the fascia dentata of adult rats at various timepoints after removal of the entorhinaI perforant path projection. Microglial cells were identified by histochemical staining for nucleoside diphosphatase (NDPase) at light and electron microscopical levels. Astroglial cells were stained immunocytoche...

Perforant path long-term potentiation (LTP) in intact mouse hippocampal dentate gyrus increased the neuron-specific, growth-associated protein GAP-43 mRNA in hilar cells 3 days after tetanus, but surprisingly not in granule cells, the perforant path target. This increase was positively correlated with level of enhancement and restricted to central hilar cells on the side of stimulation. Blockad...

We used kainic acid in rats as an animal model of temporal lobe epilepsy, and studied the synaptic transmission in hippocampal subfield CA1 of urethane-anesthetized rats in vivo. Dendritic currents were revealed by field potential mapping, using a single micropipette or a 16-channel silicon probe, followed by current source density analysis. We found that the population excitatory postsynaptic ...