Correlation of the startle reflex and Mauthner cell auditory responses in unrestrained goldfish.
Stainless-steel electrodes were implanted near the left or right. Mauthner cells (M-cells) of goldfish to determine if these cells can initiate the startle reflex evoked by a brief sinusoidal sound stimulus. Recordings of the M-cell extracellular spike were obtained for the duration of 10 experiments. Fish with chronic implants were allowed to free-swim and exposed to at least 10 consecutive sound stimuli consisting of 2 cycles of 200 Hz. Seventy-three startle responses were analysed. In 34 cases the implanted M-cell electrode was contralateral to the contracting musculature, and in each of these cases, a M-cell spike preceded the EMG response by 1-1-2-1 ms. In the reamining 39 cases the electrode was ipsilateral to the active musculature, and the M-cell only fired in one of these trails. There were no startle responses and no M-cell firings in an additional 52 tests. Since the M-cell activates contralateral motoneurones, the results indicate it is responsible for initiation of the startle reflex.
D000200:Action Potentials; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003530:Cyprinidae / Q000502:physiology*; D007839:Functional Laterality; D006054:Goldfish / Q000033:anatomy & histology / Q000502:physiology*; D007395:Interneurons / Q000502:physiology; D008526:Medulla Oblongata / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology*; D013016:Sound