Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex
Cognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cogn...
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| Format: | Article |
| Language: | English |
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Wiley
2015-01-01
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| Series: | Journal of Ophthalmology |
| Online Access: | http://dx.doi.org/10.1155/2015/179542 |
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| author | Stuart R. Steinhauer Ruth Condray Misha L. Pless |
| author_facet | Stuart R. Steinhauer Ruth Condray Misha L. Pless |
| author_sort | Stuart R. Steinhauer |
| collection | DOAJ |
| description | Cognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cognition, without modifying central processes. Pupil diameter was measured during the light reaction in 29 normal adults under three processing levels: No Task, during an easy task (Add 1), or a difficult task (Subtract 7). At three separate sessions, the pupil was treated with placebo, tropicamide (blocking the muscarinic sphincter receptor), or dapiprazole (blocking the adrenergic dilator receptor). With placebo, pupil diameter increased with increasing task difficulty. The light reaction was reduced only in the Subtract 7 condition. Dapiprazole (which decreased overall diameter) showed similar task-related changes in diameter and light reflex as for placebo. Following tropicamide (which increased overall diameter), there was a further increase in diameter only in the difficult task. Findings suggest two separate inhibitory components at the parasympathetic oculomotor center. Changes in baseline diameter are likely related to reticular activation. Inhibition of the light reaction in the difficult task is likely associated with cortical afferents. Sustained sympathetic activity also was present during the difficult task. |
| format | Article |
| id | doaj-art-25064c28680443eb9aa8b21bf13af996 |
| institution | Kabale University |
| issn | 2090-004X 2090-0058 |
| language | English |
| publishDate | 2015-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Journal of Ophthalmology |
| spelling | doaj-art-25064c28680443eb9aa8b21bf13af9962025-02-03T06:44:22ZengWileyJournal of Ophthalmology2090-004X2090-00582015-01-01201510.1155/2015/179542179542Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light ReflexStuart R. Steinhauer0Ruth Condray1Misha L. Pless2Biometrics Research Program, 151R, VA Pittsburgh Healthcare System, University Drive C, Pittsburgh, PA 15240, USABiometrics Research Program, 151R, VA Pittsburgh Healthcare System, University Drive C, Pittsburgh, PA 15240, USALeitender Arzt Neuroophthalmologie und Neurologie Augenklinik, Zentrum für Neurologie und Neurorehabilitation, Luzerner Kantonsspital, 6000 Luzern 16, SwitzerlandCognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cognition, without modifying central processes. Pupil diameter was measured during the light reaction in 29 normal adults under three processing levels: No Task, during an easy task (Add 1), or a difficult task (Subtract 7). At three separate sessions, the pupil was treated with placebo, tropicamide (blocking the muscarinic sphincter receptor), or dapiprazole (blocking the adrenergic dilator receptor). With placebo, pupil diameter increased with increasing task difficulty. The light reaction was reduced only in the Subtract 7 condition. Dapiprazole (which decreased overall diameter) showed similar task-related changes in diameter and light reflex as for placebo. Following tropicamide (which increased overall diameter), there was a further increase in diameter only in the difficult task. Findings suggest two separate inhibitory components at the parasympathetic oculomotor center. Changes in baseline diameter are likely related to reticular activation. Inhibition of the light reaction in the difficult task is likely associated with cortical afferents. Sustained sympathetic activity also was present during the difficult task.http://dx.doi.org/10.1155/2015/179542 |
| spellingShingle | Stuart R. Steinhauer Ruth Condray Misha L. Pless Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex Journal of Ophthalmology |
| title | Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex |
| title_full | Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex |
| title_fullStr | Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex |
| title_full_unstemmed | Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex |
| title_short | Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex |
| title_sort | pharmacological isolation of cognitive components influencing the pupillary light reflex |
| url | http://dx.doi.org/10.1155/2015/179542 |
| work_keys_str_mv | AT stuartrsteinhauer pharmacologicalisolationofcognitivecomponentsinfluencingthepupillarylightreflex AT ruthcondray pharmacologicalisolationofcognitivecomponentsinfluencingthepupillarylightreflex AT mishalpless pharmacologicalisolationofcognitivecomponentsinfluencingthepupillarylightreflex |