The brain exhibits organized fluctuations of neural activity, even in the absence of tasks or sensory input. A prominent type of such spontaneous activity is the alpha rhythm, which influences perception and interacts with other ongoing neural activity. It is currently hypothesized that states of decreased prestimulus α oscillations indicate enhanced neural excitability, resulting in improved p...

OBJECTIVE To understand the relationship between neuronal excitability reflected by transcranial magnetic stimulation (TMS) evoked motor potentials (MEPs) and spontaneous oscillation amplitude and phase. METHODS We combined spontaneous EEG measurement with motor cortex TMS and recorded MEP amplitudes from abductor digiti minimi (ADM). RESULTS Midrange-beta oscillations over the stimulated l...

Amphetamine, a catecholaminergic re-uptake-blocker, is able to improve neuroplastic mechanisms in humans. However, so far not much is known about the underlying physiological mechanisms. Here, we study the impact of amphetamine on NMDA receptor-dependent long-lasting excitability modifications in the human motor cortex elicited by weak transcranial direct current stimulation (tDCS). Amphetamine...

Neuroadaptations in the nucleus accumbens (NAc) are associated with the development of drug addiction. Plasticity in synaptic strength and intrinsic excitability of NAc medium spiny neurons (MSNs) play critical roles in addiction induced by different classes of abused drugs. However, it is unknown whether morphine exposure influences synaptic strength, intrinsic excitability or both in NAc. Her...

BACKGROUND Advancing age is typically accompanied by deficits in learning and memory. These deficits occur independently of overt pathology and are often considered to be a part of "normal aging." At the neuronal level, normal aging is known to be associated with numerous cellular and molecular changes, which include a pronounced decrease in neuronal excitability and an altered induction in the...

In rodents, the infralimbic (IL) region of the medial prefrontal cortex plays a key role in the recall of fear extinction. Previously we showed that fear conditioning decreases the intrinsic excitability of IL neurons, and that fear extinction reverses the depressed excitability. In the current study, we examined the time course of the extinction-induced changes in adolescent rats. Immediately ...

Chronic insomnia is a poorly understood disorder. Risk factors for developing chronic insomnia are largely unknown, yet disturbances in arousal seem to accompany the disorder. We here investigate whether insomnia patients and control participants differ with respect to one operationalization of arousal, i.e. cortical excitability. A method to directly investigate the excitability level of the h...

The excitability of the motor cortex is modulated before and after voluntary movements. Transcranial magnetic stimulation studies showed increased corticospinal excitability from about 80 and 100 ms before EMG onset for simple reaction time and self-paced movements, respectively. Following voluntary movements, there are two phases of increased corticospinal excitability from 0 to approximately ...

Head movement imposes the additional burdens on the visual system of maintaining visual acuity and determining the origin of retinal image motion (i.e., self-motion vs. object-motion). Although maintaining visual acuity during self-motion is effected by minimizing retinal slip via the brainstem vestibular-ocular reflex, higher order visuovestibular mechanisms also contribute. Disambiguating sel...

Little information is available on the pH sensitivity of the excitability properties of mammalian axons. Computer-assisted threshold tracking in humans has helped to define clinically relevant changes of nerve excitability in response to hyperventilation and ischaemia, but in vivo studies cannot directly differentiate between the impact of pH and other secondary factors. In this investigation, ...