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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.


Mean peri-stimulus time histogram (PSTH) of the average BOLD response with respect to time after target presentation for each stimulus condition (pro- or anti, leftward or rightward saccades) and projection category. CN-L, CN-R (left and right caudate nucleus), SC-L, SC-R (left and right superior colliculus), FEF-L and FEF_R both (FEF voxels connected to both CN and SC), FEF-L and FEF-R unconnected (FEF voxels not connected to CN nor SC).
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Figure 5: Mean peri-stimulus time histogram (PSTH) of the average BOLD response with respect to time after target presentation for each stimulus condition (pro- or anti, leftward or rightward saccades) and projection category. CN-L, CN-R (left and right caudate nucleus), SC-L, SC-R (left and right superior colliculus), FEF-L and FEF_R both (FEF voxels connected to both CN and SC), FEF-L and FEF-R unconnected (FEF voxels not connected to CN nor SC).

Mentions: To investigate the event-related fMRI timecourse for each condition and each FEF projection zone the PSTHs were calculated, see Figure 5. When no white matter tracts were found for a particular participant and projection, no PSTH could be calculated for that FEF subzone for any condition. PSTH calculation for FEF voxels in the left FEF-CN projection class was possible for all 11 participants and for 9 participants for the right FEF-CN projection class. For FEF–SC projection class, this was possible for 10 participants for the left SC and for 9 participants for the right SC, see also Table 1.


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)

Mean peri-stimulus time histogram (PSTH) of the average BOLD response with respect to time after target presentation for each stimulus condition (pro- or anti, leftward or rightward saccades) and projection category. CN-L, CN-R (left and right caudate nucleus), SC-L, SC-R (left and right superior colliculus), FEF-L and FEF_R both (FEF voxels connected to both CN and SC), FEF-L and FEF-R unconnected (FEF voxels not connected to CN nor SC).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Mean peri-stimulus time histogram (PSTH) of the average BOLD response with respect to time after target presentation for each stimulus condition (pro- or anti, leftward or rightward saccades) and projection category. CN-L, CN-R (left and right caudate nucleus), SC-L, SC-R (left and right superior colliculus), FEF-L and FEF_R both (FEF voxels connected to both CN and SC), FEF-L and FEF-R unconnected (FEF voxels not connected to CN nor SC).
Mentions: To investigate the event-related fMRI timecourse for each condition and each FEF projection zone the PSTHs were calculated, see Figure 5. When no white matter tracts were found for a particular participant and projection, no PSTH could be calculated for that FEF subzone for any condition. PSTH calculation for FEF voxels in the left FEF-CN projection class was possible for all 11 participants and for 9 participants for the right FEF-CN projection class. For FEF–SC projection class, this was possible for 10 participants for the left SC and for 9 participants for the right SC, see also Table 1.

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.