Neuroscience 2004 Abstract
| Presentation Number: | 302.8 |
|---|---|
| Abstract Title: | Functional MRI of optokinetic stimulation with limited and infinite lifetime random dot patterns. |
| Authors: |
Schraa-Tam, C. K.*1
; van der Lugt, A.1
; Frens, M. A.2
; van der Geest, J. N.2
1Radiology, ErasmusMC, Rotterdam, The Netherlands 2Neurosci., ErasmusMC, Rotterdam, The Netherlands |
| Primary Theme and Topics |
Sensory Systems - Vision -- Subcortical visual pathways |
| Session: |
302. Eye Movements and Perception Poster |
| Presentation Time: | Sunday, October 24, 2004 4:00 PM-5:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # U12 |
| Keywords: | fMRI, visual |
In this study we investigated how activity in the cerebellum is related to the ocular following of optokinetic stimulation. Eight healthy volunteers (of about 30 years of age) participated in three experiments. For each experiment, T2*-weighted single shot gradient echo EPI functional scans were acquired (TR/TE 3750/50ms, matrix size 64x64, slice thickness 4mm). The image data was processed with SPM-99 on both single-subject and group analysis level. In the first experiment, optokinetic eye movements were evoked by a random dot pattern with an infinite lifetime. In the second experiment, the optokinetic reflex was evoked by a random pattern of dots that had a limited lifetime (i.e., each dot was repositioned within 50 ms), which effectively excludes ocular following by smooth pursuit. As a control condition, smooth pursuit eye movements were evoked by a single dot in a third experiment. In each experiment a block design was used with three conditions of 30 seconds with 5 repetitions: the stimulus moved to the left, moved to the right or was standing still. For smooth pursuit eye movements and for the optokinetic stimulation with a random pattern of infinite lifetime dots, bilateral activations were found in the cerebellum (vermis VI) as well as in several cortical areas (e.g., area MT/V5). These results corroborate the idea of overlapping neuronal pathways for smooth pursuit and OKR. However, with random pattern of limited lifetime dots we observed activity in the cerebellar hemisphere contralateral to the direction of movement, suggestion a specific role of the cerebellum for the ocular pursuit of changing patterns. Furthermore, we observed that the amount of activation in the cerebellum was less for the stimulation with infinite lifetime dots than for stimulation with a single dot or with limited lifetime dots.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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