Päivi H. Torkkeli

Learn More
The lyriform slit-sense organ on the patella of the spider, Cupiennius salei, consists of seven or eight slits, with each slit innervated by a pair of mechanically sensitive neurons. Mechanotransduction is believed to occur at the tips of the dendrites, which are surrounded by a Na+-rich receptor lymph. We studied the ionic basis of sensory transduction in(More)
This review focuses on the structure and function of a single mechanoreceptor organ in the cuticle of spiders. Knowledge emerging from the study of this organ promises to yield general principles that can be applied to mechanosensation in a wide range of animal systems. The lyriform slit sense organ on the antero-lateral leg patella of the spider Cupiennius(More)
 Pseudorandom white-noise stimulation followed by direct spectral estimation was used to obtain linear frequency response and coherence functions from paired, but dynamically different, spider mechanosensory neurons. The dynamic properties of the two neuron types were similar with either mechanical or electrical stimulation, showing that action potential(More)
We studied the properties of voltage-activated outward currents in two types of spider cuticular mechanoreceptor neurons to learn if these currents contribute to the differences in their adaptation properties. Both types of neurons adapt rapidly to sustained stimuli, but type A neurons usually only fire one or two action potentials, whereas type B neurons(More)
Low-voltage-activated Ca(2+) currents (LVA-I(Ca)) are believed to perform several roles in neurons such as lowering the threshold for action potentials, promoting burst firing and oscillatory behavior, and enhancing synaptic excitation. They also may allow rapid increases in intracellular Ca(2+) concentration. We discovered LVA-I(Ca) in both members of(More)
Octopamine is a chemical relative of noradrenaline providing analogous neurohumoral control of diverse invertebrate physiological processes. There is also evidence for direct octopaminergic innervation of some insect peripheral tissues. Here, we show that spider peripheral mechanoreceptors are innervated by octopamine-containing efferents. The(More)
G-protein-coupled octopamine (OA) receptors mediate their effects by Ca²(+) signaling or adjusting intracellular cAMP levels. Depending on OA concentration and cell type, activation of OA receptors in excitable cells triggers excitatory or inhibitory effects, but the mechanisms by which Ca²(+) or cAMP mediates these effects are not well understood. We(More)
Voltage-activated sodium current (I(Na)) is primarily responsible for the leading edge of the action potential in many neurons. While I(Na) generally activates rapidly when a neuron is depolarized, its inactivation properties differ significantly between different neurons and even within one neuron, where I(Na) often has slowly and rapidly inactivating(More)
We measured frequency response functions between concentrations of fruit odorants and individual action potentials in large basiconic sensilla of the Drosophila melanogaster antenna. A new method of randomly varying odorant concentration was combined with rapid, continuous measurement of concentration at the antenna by a miniature photoionization detector.(More)
We have developed a primary cell culture system of antennal mechanoreceptor neurons from early-stage pupal sphinx moth Manduca sexta. Dissociated neurons from the moth antennae differentiated, grew and survived for several weeks in a conditioned culture medium. Bipolar neurons with soma diameters of 10–25 µm from the basal portion of the antennae could be(More)