Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we]
Brain circuits controlling eye movements are widely distributed and complex. The etiology of irrepressible square wave saccades is not fully understood and is likely different for different neuropathologies. In a previous study, spontaneously occurring irrepressible saccades were noted after a cereb...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
F1000 Research Ltd
2013-03-01
|
| Series: | F1000Research |
| Subjects: | |
| Online Access: | http://f1000research.com/articles/2-85/v1 |
| _version_ | 1811311822762934272 |
|---|---|
| author | James W Gnadt Christopher T Noto Jagmeet S Kanwal |
| author_facet | James W Gnadt Christopher T Noto Jagmeet S Kanwal |
| author_sort | James W Gnadt |
| collection | DOAJ |
| description | Brain circuits controlling eye movements are widely distributed and complex. The etiology of irrepressible square wave saccades is not fully understood and is likely different for different neuropathologies. In a previous study, spontaneously occurring irrepressible saccades were noted after a cerebrovascular accident that damaged the rostral superior colliculus (SC) and its commissure in a Rhesus monkey. Here, we tracked and quantified the development of similar symptoms in a Rhesus monkey caused by a lesion in the rostromedial SC and its commissure. We documented the changes in these saccadic intrusions while the monkey attempted fixation of a target on three consecutive days post-onset. On the first day, eye jerk amplitude was ~10 degrees and the direction was ~30 degrees above the left horizontal meridian. On the second day, the amplitude decreased to 6.5 degrees and the direction shifted towards vertical, ~20 degrees to the left of the vertical meridian. Size, but not direction, of the eye jerks continued to decrease until intrusions dissipated within one month. Histological examination after ~6 months from the first appearance of the intrusions revealed a lesion in the commissure of the SC. Results from this and the previous study confirm the involvement of the commissure of the SC as the common target for triggering this neuropathy. Our data suggest that commissural fibers play an important role in maintaining normal visual stability. Interrupting the commissure between the two superior colliculi causes saccadic intrusions in the form of irrepressible jerking of the eyes, probably by disrupting inhibitory signals transmitted through the commissure. Furthermore, disappearance of the symptoms suggests that inhibitory fields within the SC are plastic and can expand, possibly via inputs from inter-collicular and nigrotectal pathways. |
| first_indexed | 2024-04-13T10:24:34Z |
| format | Article |
| id | doaj.art-ee65a167d74443c795adf2cacedf2a0e |
| institution | Directory Open Access Journal |
| issn | 2046-1402 |
| language | English |
| last_indexed | 2024-04-13T10:24:34Z |
| publishDate | 2013-03-01 |
| publisher | F1000 Research Ltd |
| record_format | Article |
| series | F1000Research |
| spelling | doaj.art-ee65a167d74443c795adf2cacedf2a0e2022-12-22T02:50:21ZengF1000 Research LtdF1000Research2046-14022013-03-01210.12688/f1000research.2-85.v11166Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we]James W Gnadt0Christopher T Noto1Jagmeet S Kanwal2Department of Physiology and Biophysics, Howard University College of Medicine, Washington DC, 20059, USADepartment of Neurology, Georgetown University School of Medicine, Washington DC, 20057, USADepartment of Neurology, Georgetown University School of Medicine, Washington DC, 20057, USABrain circuits controlling eye movements are widely distributed and complex. The etiology of irrepressible square wave saccades is not fully understood and is likely different for different neuropathologies. In a previous study, spontaneously occurring irrepressible saccades were noted after a cerebrovascular accident that damaged the rostral superior colliculus (SC) and its commissure in a Rhesus monkey. Here, we tracked and quantified the development of similar symptoms in a Rhesus monkey caused by a lesion in the rostromedial SC and its commissure. We documented the changes in these saccadic intrusions while the monkey attempted fixation of a target on three consecutive days post-onset. On the first day, eye jerk amplitude was ~10 degrees and the direction was ~30 degrees above the left horizontal meridian. On the second day, the amplitude decreased to 6.5 degrees and the direction shifted towards vertical, ~20 degrees to the left of the vertical meridian. Size, but not direction, of the eye jerks continued to decrease until intrusions dissipated within one month. Histological examination after ~6 months from the first appearance of the intrusions revealed a lesion in the commissure of the SC. Results from this and the previous study confirm the involvement of the commissure of the SC as the common target for triggering this neuropathy. Our data suggest that commissural fibers play an important role in maintaining normal visual stability. Interrupting the commissure between the two superior colliculi causes saccadic intrusions in the form of irrepressible jerking of the eyes, probably by disrupting inhibitory signals transmitted through the commissure. Furthermore, disappearance of the symptoms suggests that inhibitory fields within the SC are plastic and can expand, possibly via inputs from inter-collicular and nigrotectal pathways.http://f1000research.com/articles/2-85/v1Cognitive NeuroscienceNeuro-Ophthalmology & Neuro-OtologySensory Systems |
| spellingShingle | James W Gnadt Christopher T Noto Jagmeet S Kanwal Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] F1000Research Cognitive Neuroscience Neuro-Ophthalmology & Neuro-Otology Sensory Systems |
| title | Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] |
| title_full | Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] |
| title_fullStr | Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] |
| title_full_unstemmed | Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] |
| title_short | Tectal etiology for irrepressible saccades: a case study in a Rhesus monkey [v1; ref status: indexed, http://f1000r.es/we] |
| title_sort | tectal etiology for irrepressible saccades a case study in a rhesus monkey v1 ref status indexed http f1000r es we |
| topic | Cognitive Neuroscience Neuro-Ophthalmology & Neuro-Otology Sensory Systems |
| url | http://f1000research.com/articles/2-85/v1 |
| work_keys_str_mv | AT jameswgnadt tectaletiologyforirrepressiblesaccadesacasestudyinarhesusmonkeyv1refstatusindexedhttpf1000reswe AT christophertnoto tectaletiologyforirrepressiblesaccadesacasestudyinarhesusmonkeyv1refstatusindexedhttpf1000reswe AT jagmeetskanwal tectaletiologyforirrepressiblesaccadesacasestudyinarhesusmonkeyv1refstatusindexedhttpf1000reswe |