Abstract
Passive rotation of the trunk with respect to the head evoked cervico-ocular reflex (COR) eye movements in squirrel monkeys. The amplitude of the reflex varied both within and between animals, but the eye movements were always in the same direction as trunk rotation. In the dark, the COR typically had a gain of 0.3-0.4. When animals fixated earth-stationary targets during low-frequency passive neck rotation or actively tracked moving visual targets with head movements, the COR was suppressed. The COR and vestibulo-ocular reflex (VOR) summed during passive head-on-trunk rotation producing compensatory eye movements whose gain was greater than 1.0. The firing behavior of VOR-related vestibular neurons and cerebellar flocculus Purkinje cells was studied during the COR. Passive neck rotation produced changes in firing rate related to neck position and/or neck velocity in both position-vestibular-pause neurons and eye-head-vestibular neurons, although the latter neurons were much more sensitive to the COR than the former. The neck rotation signals were reduced or reversed in direction when the COR was suppressed. Flocculus Purkinje cells were relatively insensitive to COR eye movements. However, when the COR was suppressed, their firing rate was modulated by neck rotation. These neck rotation signals summed with ocular pursuit signals when the head was used to pursue targets. We suggest that the neural substrate that produces the COR includes central VOR pathways, and that the flocculus plays an important role in suppressing the reflex when it would cause relative movement of a visual target on the retina.
Original language | English (US) |
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Pages (from-to) | 253-264 |
Number of pages | 12 |
Journal | Experimental Brain Research |
Volume | 140 |
Issue number | 3 |
DOIs | |
State | Published - 2001 |
Funding
Acknowledgements We would like to thank Jim Fuller for his helpful comments on this manuscript. We would also like to thank Steve Liske for his help in obtaining and analyzing behavioral data. This work was supported by NIH R01-EY08041.
Keywords
- Eye movements
- Flocculus
- Monkey
- Neck proprioception
- Vestibulo-ocular reflex
ASJC Scopus subject areas
- General Neuroscience