1. We have used compartmental models of reconstructed pyramidal neurons from layers 2 and 5 of cat visual cortex to investigate the nonlinear summation of excitatory synaptic input and the effectiveness of inhibitory input in countering this excitation. 2. In simulations that match the conditions of a recent experiment, dendritic saturation was significant for physiological levels of synaptic a...

Long-term potentiation (LTP) is a synaptic change supposed to provide the cellular basis for learning and memory in brain neuronal circuits. Although specific LTP expression mechanisms could be critical to determine the dynamics of repetitive neurotransmission, this important issue remained largely unexplored. In this paper, we have performed whole cell patch-clamp recordings of mossy fiber-gra...

We derive an optimal learning rule in the sense of mutual information maximization for a spiking neuron model. Under the assumption of small fluctuations of the input, we find a spike-timing dependent plasticity (STDP) function which depends on the time course of excitatory postsynaptic potentials (EPSPs) and the autocorrelation function of the postsynaptic neuron. We show that the STDP functio...

We studied the cholinergic modulation of glutamatergic transmission between neighboring layer 5 regular-spiking pyramidal neurons in somatosensory cortical slices from young rats (P10-P26). Brief bath application of 5-10 microM carbachol, a nonspecific cholinergic agonist, decreased the amplitude of evoked unitary excitatory postsynaptic potentials (EPSPs). This effect was blocked by 1 microM a...

Extra- and intracellular records were made from rat acute hippocampal slices to examine the effects of partial inhibition of Na(+)-K(+)-ATPases (Na(+)-K(+) pumps) on neuronal hyperexcitability. Bath application of the low-affinity cardiac glycoside, dihydroouabain (DHO), reversibly induced interictal-like epileptiform bursting activity in the CA1 region. Burst-firing was correlated with inhibit...

The role of adenosine A2 receptors in normal synaptic transmission and tetanus-induced long-term potentiation (LTP) was tested by stimulation of the Schaffer collateral pathway and recording of the field excitatory postsynaptic potential (EPSP) in the CA1 region of rat transverse hippocampal slices. Activation of adenosine A2 receptors with the A2 agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methyl...

Hippocampal slices obtained from C57BL/6 mice (3-25 mo) were used to investigate the effects of aging on excitatory postsynaptic potentials (EPSPs) elicited in dentate gyrus with lateral perforant path stimulation. The maximal amplitude of the EPSP, as well as the degree of paired-pulse facilitation, was significantly reduced in animals aged 12 mo or more compared with younger animals (<12 mo)....

In previous experiments on excitatory synaptic transmission in CA1, temporary (10-20 min) replacement of glucose with 10 mM 2-deoxyglucose (2-DG) consistently caused a marked and very sustained potentiation (2-DG LTP). To find out whether 2-DG has a similar effect on inhibitory synapses, we recorded pharmacologically isolated mononosynaptic inhibitory postsynaptic potentials (IPSPs; under curre...

Hippocampal slices obtained from C57BL/6 mice (3 to 25 months in age) were used to investigate the effects of aging on EPSPs (excitatory postsynaptic potentials) elicited in dentate gyrus with lateral perforant path stimulation. The maximal amplitude of the EPSP, as well as the degree of paired-pulse facilitation, were significantly reduced in animals aged 12 months or more, as compared to youn...