Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus

Vallabh E Das; R John Leigh; Michelle Swann; Matthew J Thurtell

doi:10.1007/s00221-010-2376-2

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Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus

Journal article

Peer reviewed

Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus

Vallabh E Das, R John Leigh, Michelle Swann and Matthew J Thurtell

Experimental brain research, Vol.205(3), pp.405-413

09/2010

DOI: 10.1007/s00221-010-2376-2

PMCID: PMC2965773

PMID: 20686890

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Abstract

Hemi-seesaw nystagmus (hemi-SSN) is a jerk-waveform nystagmus with conjugate torsional and disjunctive vertical components. Halmagyi et al. in Brain 117(Pt 4):789-803 (1994), reported hemi-SSN in patients with unilateral lesions in the vicinity of the Interstitial Nucleus of Cajal (INC) and suggested that an imbalance in projections from the vestibular nuclei to the INC was the source of the nystagmus. However, this hypothesis was called into question by Helmchen et al. in Exp Brain Res 119(4):436-452 (1998), who inactivated INC in monkeys with muscimol (a GABA(A) agonist) and induced failure of vertical gaze-holding (neural integrator) function but not hemi-SSN. We injected 0.1-0.2 microl of 2% muscimol into the supraoculomotor area, 1-2 mm dorso-lateral to the right oculomotor nucleus and caudal to the right INC. A total of seven injections in two juvenile rhesus monkeys were performed. Hemi-SSN was noted within 5-10 min after injection for six of the injections. Around the time the hemi-SSN began, a small skew deviation also developed. However, there was no limitation of horizontal or vertical eye movements, suggesting that the nearby oculomotor nucleus was not initially compromised. Limitations in eye movement range developed about (1/2)-1 h following the injections. Clinical signs that were observed after the animal was released to his cage included a moderate to marked head tilt toward the left (contralesional) side, consistent with an ocular tilt reaction. We conclude that hemi-SSN can be caused by lesions just caudal to the INC, whereas lesions of the INC itself cause down-beat nystagmus and vertical gaze-holding failure, as demonstrated by Helmchen et al. Combined deficits may be encountered with lesions that involve several midbrain structures.

Motor Cortex - anatomy & histology

Motor Cortex - physiology

Muscimol - pharmacology

Oculomotor Nerve - physiology

Eye Movements - physiology

Microinjections

GABA Agonists - administration & dosage

Interstitial Cells of Cajal - drug effects

Macaca mulatta

Nystagmus, Pathologic - physiopathology

Vision, Binocular - physiology

Stereotaxic Techniques

Animals

GABA Agonists - pharmacology

Functional Laterality - physiology

Nystagmus, Pathologic - chemically induced

Muscimol - administration & dosage

Details

Title: Subtitle: Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus
Creators: Vallabh E Das - College of Optometry, University of Houston, Houston, TX 77204, USA. vdas@optometry.uh.edu
R John Leigh
Michelle Swann
Matthew J Thurtell
Resource Type: Journal article
Publication Details: Experimental brain research, Vol.205(3), pp.405-413
DOI: 10.1007/s00221-010-2376-2
PMID: 20686890
PMCID: PMC2965773
NLM abbreviation: Exp Brain Res
ISSN: 0014-4819
eISSN: 1432-1106
Publisher: Germany
Grant note: R01 EY006717-25 / NEI NIH HHS P51 RR000165 / NCRR NIH HHS R01-EY06717 / NEI NIH HHS P30 EY007551 / NEI NIH HHS R01 EY015312 / NEI NIH HHS RR00165 / NCRR NIH HHS P30 EY 07551 / NEI NIH HHS R01 EY015312-06 / NEI NIH HHS R01-EY015312 / NEI NIH HHS R01 EY006717 / NEI NIH HHS
Language: English
Date published: 09/2010
Academic Unit: Neurology; Ophthalmology and Visual Sciences
Record Identifier: 9983980077302771

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