γ-Amino butyric acid (GABA) plays a key role in the regulation of central nervous system by activating synaptic and extrasynaptic GABAA receptors. It is acknowledged that extrasynaptic GABAA receptors located in the soma, dendrites, and axons may be activated tonically by low extracellular GABA concentrations. The activation of these receptors produces a persistent conductance that can hyperpol...

OBJECTIVE To examine the contribution of reverse mode sodium-calcium (Na-Ca) exchange to contractions in isolated left-ventricular myocytes from failing human heart. METHODS Low resistance patch pipettes were used to dialyze cells with Na-free or high-Na pipette solution ([Na]pipette = 0 and 20 mmol/L, respectively) to reduce or enhance Na-Ca exchange. Whole-cell membrane-potential, membrane-...

RATIONALE Adult rats emit ultrasonic vocalizations (USVs) at around 50-kHz; these commonly occur in contexts that putatively engender positive affect. While several reports indicate that dopaminergic (DAergic) transmission plays a role in the emission of 50-kHz calls, the pharmacological evidence is mixed. Different modes of dopamine (DA) release (i.e., tonic and phasic) could potentially expla...

Comparisons were made of muscle spindle structure between phasic and tonic muscles stained by the gold chloride method. The most significant difference was in the ring diameter of the sensory nerve terminals wrapped around the nuclear bags. In tibialis anterior it was largest, in gastrocnemius intermediate, and in soleus smallest. This order corresponds to the contraction time, tibialis anterio...

Phasic increases and decreases in dopamine (DA) transmission encode reward prediction errors thought to facilitate reward-related learning, yet how these signals guide action selection in more complex situations requiring evaluation of different reward remains unclear. We manipulated phasic DA signals while rats performed a risk/reward decision-making task, using temporally discrete stimulation...

These studies sought to test the hypothesis that prostaglandin F2α(PGF2α)-stimulated phasic myometrial contractions are characterized by the activation of the phosphatidylinositol-signaling pathway resulting in the generation of cytosolic calcium oscillations. For the experiments described in this report rat myometrial tissue was used, after the tissue was loaded with fura 2, to perform cytosol...

Midbrain dopamine (DA) neurons fire in 2 characteristic modes, tonic and phasic, which are thought to modulate distinct aspects of behavior. However, the inability to selectively disrupt these patterns of activity has hampered the precise definition of the function of these modes of signaling. Here, we addressed the role of phasic DA in learning and other DA-dependent behaviors by attenuating D...

Spatiotemporal activity patterns of neurones are organized by different types of coherent network oscillations. Frequency content and cross-frequency coupling of cortical oscillations are strongly state-dependent, indicating that different patterns of wakefulness or sleep, respectively, support different cognitive or mnestic processes. It is therefore crucial to analyse specific sleep patterns ...

Decision-makers often arrive at different choices when faced with repeated presentations of the same evidence. Variability of behavior is commonly attributed to noise in the brain's decision-making machinery. We hypothesized that phasic responses of brainstem arousal systems are a significant source of this variability. We tracked pupil responses (a proxy of phasic arousal) during sensory-motor...

xvi DIFFERENTIAL REGULATION OF MLC20 PHOSPHORYLATION IN TONIC AND PHASIC SMOOTH MUSCLES OF THE STOMACH By Othman A. Al-Shboul, Ph.D. A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2011 Major Director: S.Murthy Karnam Professor, Department of Physiology Gastrointestinal (G...