Mechanosensory neurons with bend- and osmo-sensitivity in mouthpart setae from the spiny lobster Panulirus argus.
The mouthparts of the spiny lobster Panulirus argus hold primarily two types of setae--simple setae and cuspidate setae. Mechanosensory neurons from these setae were examined by electrophysiological recordings. The population of simple setae contained two types of mechanosensory neurons: displacement-sensitive neurons, which responded to deflection at the setal base; and bend-sensitive neurons, which responded to bending of the setal shaft. Displacement-sensitive neurons, in general, responded phasically and only during actual displacement. Typically, their response changed with alteration of the direction, amplitude, and velocity/acceleration of the mechanical stimulus. Bend-sensitive neurons, in general, responded phaso-tonically and carried information on the direction and region of bending. This is the first experimental demonstration of bend sensitivity for arthropod setae. Cuspidate setae contain highly sensitive mechanosensory neurons; however, due to the rigid nature of these setae, whether they were bend sensitive or displacement sensitive could not be determined, and they were thus called "tactile neurons." Bend-sensitive neurons, but not displacement-sensitive neurons or tactile neurons, showed graded responses to changes in osmolarity. The osmosensitivity of these neurons could mediate behavioral responses to changes in the osmolarity of seawater or food.
Garm
Anders
A
Zoological Institute, University of Copenhagen, Denmark. anders.garm@cob.lu.se
Derby
Charles D
CD
Høeg
Jens T
JT
D000818:Animals; D002628:Chemoreceptor Cells / Q000502:physiology; D004594:Electrophysiology; D008465:Mechanoreceptors / Q000502:physiology*; D009055:Mouth / Q000033:anatomy & histology / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D033521:Palinuridae / Q000033:anatomy & histology / Q000502:physiology*; D010812:Physical Stimulation; D014741:Video Recording