Activation of superior colliculi in humans during visual exploration

被引:20
作者
Himmelbach, Marc
Erb, Michael
Karnath, Hans-Otto
机构
[1] Univ Tubingen, Hertie Inst Clin Brain Res, Ctr Neurol, Sect Neuropsychol, D-72076 Tubingen, Germany
[2] Univ Tubingen, Dept Neuroradiol, Sect Expt NMR, D-72076 Tubingen, Germany
关键词
D O I
10.1186/1471-2202-8-66
中图分类号
Q189 [神经科学];
学科分类号
071006 [神经生物学];
摘要
Background: Visual, oculomotor, and - recently - cognitive functions of the superior colliculi ( SC) have been documented in detail in non- human primates in the past. Evidence for corresponding functions of the SC in humans is still rare. We examined activity changes in the human tectum and the lateral geniculate nuclei ( LGN) in a visual search task using functional magnetic resonance imaging ( fMRI) and anatomically defined regions of interest ( ROI). Healthy subjects conducted a free visual search task and two voluntary eye movement tasks with and without irrelevant visual distracters. Blood oxygen level dependent ( BOLD) signals in the SC were compared to activity in the inferior colliculi ( IC) and LGN. Results: Neural activity increased during free exploration only in the SC in comparison to both control tasks. Saccade frequency did not exert a significant effect on BOLD signal changes. No corresponding differences between experimental tasks were found in the IC or the LGN. However, while the IC revealed no signal increase from the baseline, BOLD signal changes at the LGN were consistently positive in all experimental conditions. Conclusion: Our data demonstrate the involvement of the SC in a visual search task. In contrast to the results of previous studies, signal changes could not be seen to be driven by either visual stimulation or oculomotor control on their own. Further, we can exclude the influence of any nearby neural structures ( e. g. pulvinar, tegmentum) or of typical artefacts at the brainstem on the observed signal changes at the SC. Corresponding to findings in non- human primates, our data support a dependency of SC activity on functions beyond oculomotor control and visual processing.
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页数:7
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