Phasic and tonic γ-aminobutyric acidA (GABAA) receptor-mediated inhibition critically regulate neuronal information processing. As these two inhibitory modalities have distinctive features in their receptor composition, subcellular localization of receptors, and the timing of receptor activation, it has been thought that they might exert distinct roles, if not completely separable, in the regul...

We report a case of unilateral tonic pupil in spinocerebellar ataxia without brainstem atrophy in a 42year-old man. On neurological examination, he showed cerebellar symptoms and unilateral tonic pupil. Deep tendon reflexes were normal except for brisk patellar tendon reflexes. Brain MRI demonstrated cerebellar atrophy only. There was neither orthostatic hypotension nor bowel and bladder failur...

Desynchronized sleep (DS) in the cat is accompanied by a long-lasting (tonic) constriction of muscle blood vessels (conductance decrease 5-30%), on which are superimposed short-lasting (phasic) vasoconstrictor waves that occur simultaneously with bursts of rapid eye movements and body twitches. Both the tonic and the phasic vasoconstrictions are abolished after regional sympathectomy (conductan...

Tonic inhibition plays a crucial role in regulating neuronal excitability because it sets the threshold for action potential generation and integrates excitatory signals. Tonic currents are known to be largely mediated by extrasynaptic gamma-aminobutyric acid type A (GABA(A)) receptors that are persistently activated by submicromolar concentrations of ambient GABA. We recently reported that, in...

Neurons in the lateral geniculate nucleus (LGN) of the thalamus produce spikes that can be classified as burst spikes and tonic spikes. Although burst spikes are generally associated with states of sleep and drowsiness, bursts may also play an important role in sensory processing. This study explores the stimulus properties that evoke burst and tonic spikes and examines the reliability of LGN n...

The tonic contraction of human and guinea pig gallbladder (GB) is dependent on basal levels of PGE(2) and thromboxane A(2) (TxA(2)). The pathway involved in the genesis of these prostaglandins has not been elucidated. We aimed to examine the source of reactive oxygen species (ROS) and whether they contribute to the genesis of GB tonic contraction by generating basal prostaglandin levels. Tonic ...

UNLABELLED Tonic spasms have been most commonly associated with multiple sclerosis. To date, few reports of series of patients with neuromyelitis optica and tonic spasms have been published. METHODS We analyzed the characteristics and frequency of tonic spasms in 19 subjects with neuromyelitis optica. Data was collected using a semi-structured questionnaire for tonic spasms, by both retrospec...

Tonic immobility, characterized by profound motor inhibition, is elicited under inescapable threat in many species. To fully support the existence of tonic immobility in humans, our aim was to elicit this reaction in a laboratory setting and measure it objectively. To mimic exposure to life-threatening events in the lab, trauma-exposed participants with PTSD (n=18) and without PTSD (n=15) liste...

Tonic inhibition mediated by extrasynaptic GABA(A) receptors (GABA(A)Rs) has emerged as a novel form of neural inhibition in the CNS. However, little is known about its presence and function in the auditory system. Using whole-cell recordings in brain slices, we identified a tonic current mediated by GABA(A)Rs containing the δ subunit in middle/high-characteristic-frequency neurons of the chick...

It is now well established that accommodation adopts an intermediate resting position in the absence of visual stimulation. It also has been shown that this tonic position of accommodation exhibits considerable variation among individuals (ie, 0-4 D). Previous studies have been somewhat inconclusive as to whether these individual differences in tonic accommodation are related to the refractive ...