Descending projections from the cortical accommodation area in the cat.
OBJECTIVE
Results in previous studies indicated that the lateral suprasylvian (LS) area, the cortical area surrounding the middle suprasylvian sulcus (Mss) of the cat, has important roles in the control of accommodation. The current study was conducted to investigate descending projections from the accommodation-related area in the LS area to the brainstem.


METHODS
Wheat germ agglutinin-horseradish peroxydase (WGA-HRP) was injected into the accommodation-related area in the pretectum or in the rostral superior colliculus (SC) of the cat. These regions are thought to be involved in the control of accommodation based on results of previous studies. The authors investigated locations of retrogradely labeled cells in the LS area. In addition, the authors compared amplitudes of accommodative responses evoked by stimulation of the LS area before and after neuronal activities in the rostral SC were inhibited by the injection of muscimol (gamma-aminobutyric acid agonist) into the accommodation-related area in the rostral SC.


RESULTS
After injections of WGA-HRP into the accommodation-related area in the rostral SC, retrogradely labeled cells were observed in the lower part of the medial bank of the Mss, which corresponded to the accommodation-related area in the LS area. Conversely, after injections of WGA-HRP into the accommodation-related area in the pretectum, retrogradely labeled cells were seen in the upper part of the medial bank of the Mss, which did not correspond to the accommodation-related area in the LS area. Accommodation responses evoked by stimulation of the LS area were abolished by the injection of muscimol into the accommodation-related area in the rostral SC.


CONCLUSIONS
These findings suggest that accommodation-related signals from the LS area mainly project to the rostral SC, but not to the pretectum.
Ohtsuka
K
K
Department of Ophthalmology, School of Medicine, Sapporo Medical University, Japan.
Sato
A
A
D000065:Accommodation, Ocular / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D002415:Cats; D004558:Electric Stimulation; D018755:GABA Agonists / Q000494:pharmacology; D015335:Molecular Probes; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011680:Pupil / Q000502:physiology; D013477:Superior Colliculi / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D014793:Visual Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D018755:GABA Agonists; D015335:Molecular Probes; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D009118:Muscimol