A frequency and time domain study of the horizontal and vertical vestibuloocular reflex in the pigeon

T. J. Anastasio, M. J. Correia

Research output: Contribution to journalArticlepeer-review

Abstract

The horizontal and vertical vestibuloocular reflex (HVOR and VVOR, respectively) was studied in four chronically instrumented pigeons. Eye movements were measured, using the magnetic search-coil technique and were produced by rotation in the dark. During the rotation paradigms, the pigeons were either pharmacologically aroused (using amphetamine) or drug free (normal). The pigeon HVOR and VVOR were tested using step and sinusoidal rotational stimulation. The range of frequencies (0.03-6.0 Hz) and the magnitude of the sinusoidal stimuli were chosen to match those used in a previous study of the responses of semicircular canal primary afferents (SCPAs) in unanesthetized (i.e., normal) pigeons. The gain of the HVOR and VVOR in both normal and aroused pigeons was independent of stimulus magnitude (6-30°/s) over the frequency range tested. In aroused pigeons, the frequency independent gain (G) of the HVOR (G = 0.6) and VVOR (G = 0.9) was roughly twice that for normal pigeons. Pigeon VOR phase under all combinations of orientation and arousal level was independent of stimulus magnitude except at the lowest frequency tested (0.03 Hz). At this frequency, phase lead decreased as stimulus magnitude increased for the HVOR and VVOR in both normal and aroused pigeons. The step and sinusoidal gains were greater for the VVOR than for the HVOR under the same level of arousal. Neither the gain nor the dominant time constant of the VOR (τ(vor)) differed for rotation direction (clockwise or counterclockwise) for the HVOR or VVOR in normal or aroused pigeons. The mean value of τ(vor) was 4.0 ± 0.5 (SE) s as estimated from frequency response data and 4.3 ± 0.4 s as estimated from step response data for the HVOR and VVOR in both normal and aroused pigeons. In comparison, the mean value of the dominant or cupular time constant (τ(c)) of normal pigeon SCPAs was ~10 s as estimated from frequency response data. These results indicate that τ(vor) is shorter than τ(c) in the pigeon. At higher frequencies, the pigeon HVOR and VVOR exhibit an increasing phase lag unaccompanied by a gain change - characteristics produced by a pure time delay. The value of this time delay was about 7 ms for both the HVOR and VVOR in both normal and aroused pigeons. The HVOR and VVOR in normal and aroused pigeons lacked the higher frequency lead characteristics present in the frequency responses of most pigeon SCPAs.

Original languageEnglish (US)
Pages (from-to)1143-1161
Number of pages19
JournalJournal of neurophysiology
Volume59
Issue number4
DOIs
StatePublished - 1988
Externally publishedYes

ASJC Scopus subject areas

  • General Neuroscience
  • Physiology

Fingerprint

Dive into the research topics of 'A frequency and time domain study of the horizontal and vertical vestibuloocular reflex in the pigeon'. Together they form a unique fingerprint.

Cite this