Inductive neural telemetry was used to record from microwire electrodes chronically implanted into the anterior lateral line nerve of the toadfish, Opsanus tau. Spontaneous neural activity and the response of lateral line fibers to water current were continually monitored from 17 primary afferent fibers before, during, and after the administration of the anesthetic tricaine (MS-222). Significant decrease in spontaneous and evoked activity and increase in interspike interval was noted when anesthetic concentrations were ≥0.010%. Neural activity returned to control levels within ∼90 min of anesthetic withdrawal. Decreasing the pH of the solution without the anesthetic caused transient heightened sensitivity, indicating that tricaine and not the concurrent drop in pH was responsible for the decrease in sensitivity during anesthesia. During a secondary challenge with the anesthetic 24 h after the first, fibers initially showed faster recovery however overall recovery kinetics were similar. Although high tricaine concentration was correlated with decreased neural sensitivity, the concentrations normally used to maintain anesthesia in the toadfish did not have significant effect on the evoked firing rate. Thus given sufficient time to recover from the induction of surgical anesthesia, it may be possible to maintain the animal under light anesthesia while minimizing the physiological effects of tricaine.

Regeneration of the teleost retina following surgical extirpation of 25% to 100% of the neural retina was investigated in goldfish (Carrasius auratus) and sunfish (Lepomis cyanellus). The retina will regenerate following removal of up to 95% of the neural retina, however complete extirpation prevented regeneration. Visual sensitivity was assessed by examining components of the electroretinogram (ERG) and the dorsal light reflex (DLR) during regeneration. B-wave amplitudes in the experimental eyes increased throughout the study and central connections were reestablished as indicated by the progressive improvement in the dorsal light reflex. The recovery of visual function was closely correlated with retinal regeneration. Visual recovery progressed more slowly than following complete cytotoxic destruction of the mature retina (Mensinger & Powers, 1999) because the surgery removed a large number of the pluripotent cell population and restricted the number and distribution of regenerating foci.

Inductive neural telemetry was used to record from microwire electrodes chronically implanted into the anterior lateral line nerve of the oyster toadfish, Opsanus tau (L.). The lateral lines of free-ranging toadfish were stimulated by the swimming movements of a prey fish (Fundulus heteroclitus), and the corresponding neural activity was quantified. Both spontaneously active and silent afferent fibers experienced an increase in neural firing as the prey approached the lateral line. Activity was evoked when the prey fish approached to within 8-12 cm of the neuromast, with increases in nerve firing rates directly correlated with diminishing distance. Thus, adult toadfish (28 cm standard length; 33 cm total length) were only able to detect mobile prey that approached within approximately 40% of their body length. Both spontaneously active and silent afferent fibers also experienced a dramatic increase in firing during predatory strikes, indicating that the fibers were not inhibited during rapid body movement. This study investigates, for the first time, the neural response of the anterior lateral line to prey stimuli in free-ranging fish.