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Human fronto-tectal and fronto-striatal-tectal pathways activate differently during anti-saccades.

de Weijer AD, Mandl RC, Sommer IE, Vink M, Kahn RS, Neggers SF - Front Hum Neurosci (2010)

Bottom Line: In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG.This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN.These findings suggest that activity along the contralateral FEF-SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht Utrecht, Netherlands.

ABSTRACT
Almost all cortical areas in the vertebrate brain take part in recurrent connections through the subcortical basal ganglia (BG) nuclei, through parallel inhibitory and excitatory loops. It has been suggested that these circuits can modulate our reactions to external events such that appropriate reactions are chosen from many available options, thereby imposing volitional control over behavior. The saccade system is an excellent model system to study cortico-BG interactions. In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG. In an event-related functional magnetic resonance imaging (fMRI) paradigm participants made pro- and anti-saccades. A diffusion tensor imaging (DTI) scan was made for reconstruction of white matter tracts between the FEF, CN and SC. DTI fiber tracts were used to divide both the left and right FEF into two sub-areas, projecting to either ipsilateral SC or CN. For each of these FEF zones an event-related fMRI timecourse was extracted. In general activity in the FEF was larger for anti-saccades. This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN. These findings suggest that activity along the contralateral FEF-SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade.

No MeSH data available.


Spatial distribution of FEF voxels connected to the SC (red circles) or to the CN (blue circles), in MNI space, plotted in coronal view for four subjects. The circles are projected to a 2D coronal plane coinciding with a coronal section of the T1 scan normalized to MNI, halfway the selected cluster of voxels to indicate their position with respect to the individual cerebral anatomy. Note that the distribution of selected FEF voxels entails 3 dimensions, and the T1 coronal section only 2. This projection is therefore only indicative of the course anatomical location of the voxels and does not exactly match sulcal anatomy.
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Figure 4: Spatial distribution of FEF voxels connected to the SC (red circles) or to the CN (blue circles), in MNI space, plotted in coronal view for four subjects. The circles are projected to a 2D coronal plane coinciding with a coronal section of the T1 scan normalized to MNI, halfway the selected cluster of voxels to indicate their position with respect to the individual cerebral anatomy. Note that the distribution of selected FEF voxels entails 3 dimensions, and the T1 coronal section only 2. This projection is therefore only indicative of the course anatomical location of the voxels and does not exactly match sulcal anatomy.

Mentions: To investigate whether the FEF projection zones are located on a particular side of the FEF for most participants, the average coordinates of the classified clusters were transformed from native space to MNI stereotactic atlas space (comparable to Talairach). Using the ‘unified segmentation’ algorithm in SPM5 (Ashburner and Friston, 2005), an inverse normalization warping field was obtained from the high contrast T1-weighted structural scan that can be used to transform individual coordinates to MNI coordinates. See Figure 4 for the layout in MNI space of FEF voxels uniquely projecting to the CN and the SC from four representative participants, overlaid on a slice (through the center of the cluster of voxels dubbed FEF) from the normalized structural T1-weighted anatomical scan.


Human fronto-tectal and fronto-striatal-tectal pathways activate differently during anti-saccades.

de Weijer AD, Mandl RC, Sommer IE, Vink M, Kahn RS, Neggers SF - Front Hum Neurosci (2010)

Spatial distribution of FEF voxels connected to the SC (red circles) or to the CN (blue circles), in MNI space, plotted in coronal view for four subjects. The circles are projected to a 2D coronal plane coinciding with a coronal section of the T1 scan normalized to MNI, halfway the selected cluster of voxels to indicate their position with respect to the individual cerebral anatomy. Note that the distribution of selected FEF voxels entails 3 dimensions, and the T1 coronal section only 2. This projection is therefore only indicative of the course anatomical location of the voxels and does not exactly match sulcal anatomy.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2903195&req=5

Figure 4: Spatial distribution of FEF voxels connected to the SC (red circles) or to the CN (blue circles), in MNI space, plotted in coronal view for four subjects. The circles are projected to a 2D coronal plane coinciding with a coronal section of the T1 scan normalized to MNI, halfway the selected cluster of voxels to indicate their position with respect to the individual cerebral anatomy. Note that the distribution of selected FEF voxels entails 3 dimensions, and the T1 coronal section only 2. This projection is therefore only indicative of the course anatomical location of the voxels and does not exactly match sulcal anatomy.
Mentions: To investigate whether the FEF projection zones are located on a particular side of the FEF for most participants, the average coordinates of the classified clusters were transformed from native space to MNI stereotactic atlas space (comparable to Talairach). Using the ‘unified segmentation’ algorithm in SPM5 (Ashburner and Friston, 2005), an inverse normalization warping field was obtained from the high contrast T1-weighted structural scan that can be used to transform individual coordinates to MNI coordinates. See Figure 4 for the layout in MNI space of FEF voxels uniquely projecting to the CN and the SC from four representative participants, overlaid on a slice (through the center of the cluster of voxels dubbed FEF) from the normalized structural T1-weighted anatomical scan.

Bottom Line: In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG.This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN.These findings suggest that activity along the contralateral FEF-SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht Utrecht, Netherlands.

ABSTRACT
Almost all cortical areas in the vertebrate brain take part in recurrent connections through the subcortical basal ganglia (BG) nuclei, through parallel inhibitory and excitatory loops. It has been suggested that these circuits can modulate our reactions to external events such that appropriate reactions are chosen from many available options, thereby imposing volitional control over behavior. The saccade system is an excellent model system to study cortico-BG interactions. In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG. In an event-related functional magnetic resonance imaging (fMRI) paradigm participants made pro- and anti-saccades. A diffusion tensor imaging (DTI) scan was made for reconstruction of white matter tracts between the FEF, CN and SC. DTI fiber tracts were used to divide both the left and right FEF into two sub-areas, projecting to either ipsilateral SC or CN. For each of these FEF zones an event-related fMRI timecourse was extracted. In general activity in the FEF was larger for anti-saccades. This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN. These findings suggest that activity along the contralateral FEF-SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade.

No MeSH data available.