Propagating wave segments are stabilized to a constant size and shape by applying negative feedback from the measured wave area to the excitability of the medium. The locus of steady-state wave size as a function of excitability defines the perturbation threshold for the initiation of spiral waves. This locus also defines the excitability boundary for spiral wave behavior in active media.

Measurements were made of resting potentials, input resistance, and excitability to intracellularly applied, depolarizing current pulses in neurons of the pericruciate cortex of conscious cats before and after acquisition of a rapidly conditioned eye blink reflex (CR). Neuronal excitability increased after conditioning, and an increased input resistance was found to be correlated with the incre...

Studies on noninvasive motor cortex stimulation and motor learning demonstrated cortical excitability as a marker for a learning effect. Transcranial direct current stimulation (tDCS) is a non-invasive tool to modulate cortical excitability. It is as yet unknown how tDCS-induced excitability changes and perceptual learning in visual cortex correlate. Our study aimed to examine the influence of ...

Modulation of afterhyperpolarization (AHP) represents an important mechanism by which excitability of a neuron can be regulated. In the leech brain, sensitization enhances excitability of the S-cell, an interneuron thought to play an important role in this form of nonassociative learning. This increase in excitability is serotonin (5-HT) dependent, but it is not known whether changes in AHP con...

Microelectrode techniques were used to investigate the effects of rate and rhythm changes upon the period of supernormal excitability during repolarization in isolated canine right and left bundle branch and Purkinje fibers. The same microelectrode was used for both intracellular stimulation and recording. Excitability curves (strength-interval curves) were measured as the minimum depolarizing ...

The production of movement in a simple reaction time task can be separated into two time periods: the foreperiod, which is thought to include preparatory processes, and the reaction time interval, which includes initiation processes. To better understand these processes, transcranial magnetic stimulation has been used to probe corticospinal excitability at various time points during response pr...

Although plasticity at excitatory synapses is widely studied as a mechanism for memory formation, less is known about the properties and mechanisms underlying activity-dependent changes in excitability. Using extracellular and intracellular recordings in hippocampal slices, we find that short trains (2-3 s) of Schaffer collateral fiber stimulation delivered at 5 Hz induce a robust and persisten...

While previous studies have assessed changes in corticospinal excitability following voluntary contraction coupled with electrical stimulation (ES), we sought to examine, for the first time in the field, real-time changes in corticospinal excitability. We monitored motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation and recorded the MEPs using a mechanomyogram, which is...

Although multiple toxins have been implicated in the development of uraemic neuropathy, no causative agent has been identified. In the present study, the excitability properties of lower limb motor nerves in patients with end-stage kidney disease treated with haemodialysis were measured before, during and after a standard 5 h haemodialysis session, in an attempt to explore the pathophysiology o...

OBJECTIVE The objective of this study was to determine if an initial transient state influences the acquisition of reliable estimates of corticospinal excitability in transcranial magnetic stimulation (TMS) studies. Whereas muscle evoked potential (MEP) amplitudes are an important index of cortical excitability, these are severely limited by sweep-to-sweep variability. Interesting in this conte...