Steady-state centrifugal input via the lateral olfactory tract modulates spontaneous activity in the rat main olfactory bulb.

Mitral and tufted cells in the main olfactory bulb (MOB) of anesthetized rats exhibit vigorous spontaneous activity, action potentials produced in the absence of odor stimuli. The central hypothesis of this paper is that tonic activity of centrifugal input to the MOB modulates the spontaneous activity of MOB neurons. The spontaneous activity of centrifugal fibers causes a baseline of steady-state neurotransmitter release, and odor stimulation produces transient changes in the resulting spontaneous activity.

Changing undergraduate human anatomy and physiology laboratories: perspectives from a large-enrollment course.

In the present article, a veteran lecturer of human anatomy and physiology taught several sections of the laboratory component for the first time and shares his observations and analysis from this unique perspective. The article discusses a large-enrollment, content-heavy anatomy and physiology course in relationship to published studies on learning and student self-efficacy. Changes in the laboratory component that could increase student learning are proposed.

A selective PMCA inhibitor does not prolong the electroolfactogram in mouse.

Background: Within the cilia of vertebrate olfactory receptor neurons, Ca(2+) accumulates during odor transduction. Termination of the odor response requires removal of this Ca(2+), and prior evidence suggests that both Na(+)/Ca(2+) exchange and plasma membrane Ca(2+)-ATPase (PMCA) contribute to this removal.

Principal Findings: In intact mouse olfactory epithelium, we measured the time course of termination of the odor-induced field potential.

The source of spontaneous activity in the main olfactory bulb of the rat.

Introduction: In vivo, most neurons in the main olfactory bulb exhibit robust spontaneous activity. This paper tests the hypothesis that spontaneous activity in olfactory receptor neurons drives much of the spontaneous activity in mitral and tufted cells via excitatory synapses.

Methods: Single units were recorded in vivo from the main olfactory bulb of a rat before, during, and after application of lidocaine to the olfactory nerve.

Physiological evidence for two classes of mitral cells in the rat olfactory bulb.

The spontaneous activity of mitral cells was recorded in vivo from the main olfactory bulb of freely breathing anesthetized rats. Single units recorded extracellularly from the mitral cell body layer were further identified as mitral cells by antidromic activation of the lateral olfactory tract and the posterior piriform cortex. Hierarchical cluster analysis of their spontaneous activity showed that at least two classes of mitral cells could be distinguished.

A housefly sensory-motor integration laboratory.

Insects have many interesting behaviors that can be observed in an introductory biology laboratory setting. In the present article, we describe several reflexes using the housefly Musca domestica that can be used to introduce students to sensory and motor responses and encourage them to think about the underlying neural circuits and integration of sensory information that mediate the behaviors.

Comparison of identified mitral and tufted cells in freely breathing rats: II. Odor-evoked responses.

Mitral and tufted cells are the 2 types of output neurons of the main olfactory bulb. They are located in distinct layers, have distinct projection patterns of their dendrites and axons, and likely have distinct relationships with the intrabulbar inhibitory circuits. They could thus be functionally distinct and process different aspects of olfactory information.

Comparison of identified mitral and tufted cells in freely breathing rats: I. Conduction velocity and spontaneous activity.

The spontaneous activity and impulse conduction velocities of mitral and tufted cells were compared in the entire main olfactory bulb of freely breathing, anesthetized rats. Single units in the mitral cell body layer (MCL) and external plexiform layer (EPL) were identified by antidromic activation from the lateral olfactory tract (LOT), electrode track reconstructions based on dye marking, and the waveform of LOT-evoked field potentials. Using the track reconstructions, EPL units were further subdivided into glomerular border (GB) and not at the glomerular border (notGB) cells.

The effects of analgesic supplements on neural activity in the main olfactory bulb of the mouse.

We evaluated ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID), as an antinociceptive supplement to chloral hydrate anesthesia in mouse. Effects of ketoprofen on main olfactory bulb (MOB) neuronal spontaneous activity were investigated using extracellular recordings in mouse in vivo. These effects were compared with those of another nociceptive supplement, the mu-opioid agonist buprenorphine.

In vivo preparation and identification of mitral cells in the main olfactory bulb of the mouse.

The mouse main olfactory bulb (MOB) is commonly used as a mammalian model to study olfactory processing. The genetic techniques available with the mouse make its MOB a powerful model for analysis of neuronal circuitry. The mouse has been used as a mammalian model for all types of MOB neurons, but especially to study the activity of mitral cells.

Impulse conduction of olfactory receptor neuron axons.

Compound action potentials were recorded from rat olfactory receptor neuron axons at measured distances from the stimulation electrode along the lateral surface of the main olfactory bulb. Distances were plotted as a function of the latencies measured from stimulus onset to the prominent negative trough of the triphasic compound action potential. A straight line was fitted to these data to calculate impulse conduction velocity, 0.