Activation and deactivation map during smooth and saccadic tracking in humans

2553 

Abstract Submission 

Tetsuya Yamamoto^1,2, Kenichiro Miura³, Keiji Matsuda⁴, Junya Matsumoto³, Ryota Hashimoto³, Seiji Ono⁵, Masaki Fukunaga^1,2, Norihiro Sadato^1,2,6

¹National Institute for Physiological Sciences, Okazaki, Japan, ²The Graduate University for Advanced Studies (SOKENDAI), Hayama, Japan, ³National Center of Neurology and Psychiatry, Kodaira, Japan, ⁴National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan, ⁵University of Tsukuba, Tsukuba, Japan, ⁶Ritsumeikan University, Kusatsu, Japan

Tetsuya Yamamoto  
National Institute for Physiological Sciences|The Graduate University for Advanced Studies (SOKENDAI)
Okazaki, Japan|Hayama, Japan

Kenichiro Miura  
National Center of Neurology and Psychiatry
Kodaira, Japan

Keiji Matsuda  
National Institute of Advanced Industrial Science and Technology
Tsukuba, Japan

Junya Matsumoto  
National Center of Neurology and Psychiatry
Kodaira, Japan

Ryota Hashimoto  
National Center of Neurology and Psychiatry
Kodaira, Japan

Seiji Ono  
University of Tsukuba
Tsukuba, Japan

Masaki Fukunaga  
National Institute for Physiological Sciences|The Graduate University for Advanced Studies (SOKENDAI)
Okazaki, Japan|Hayama, Japan

Norihiro Sadato  
National Institute for Physiological Sciences|The Graduate University for Advanced Studies (SOKENDAI)|Ritsumeikan University
Okazaki, Japan|Hayama, Japan|Kusatsu, Japan

Two eye movement systems, smooth pursuit and saccade, are working together in visual tracking to maintain the fixation on an object moving in our surroundings and recognize its details. Abnormal visual tracking is often accompanied with neurological and psychiatric disorders. Elucidation of the neural mechanism underlying these oculomotor behaviors will give insight into the pathological mechanisms of diseases.
The neural networks and their functions underlying smooth pursuit and saccade have been extensively discovered in non-human primates. Findings of brain activities during visual tracking are now being accumulated in humans using fMRI. More recently, the Human Connectome Project (HCP) is undertaking a systematic effort to map macroscopic human brain circuits and their relationship to behavior in a large population of healthy adults (Glasser et al., 2016). A set of the standardized image acquisition protocol (Van Essen et al., 2012) and data processing pipelines (Glasser et al., 2013) has enabled outstanding preprocessing of spatiotemporally high-resolution images. These applications in fMRI studies can thus provide more accurate activation maps during tasks, in turn resulting in novel findings.
The present study attempted to elaborate brain activation during visually-guided smooth and saccadic tracking by acquiring whole-brain fMRI data with high spatiotemporal resolution in compliance with the HCP Protocol. Herein, we aimed to determine not only visual-tracking related activation but also deactivation and differences in activation between two different types of tracking, including subcortical regions.

All MRI data were acquired on a 3-T MRI scanner according to a modified HCP Protocol (fMRI scanning parameters: TR = 0.8 s; 2-mm isotropic resolution; 72 slices; multiband factor = 8). This enabled sophisticated preprocessing including image distortion corrections, noise removal of time series data based on independent component analysis (Griffanti et al., 2014), and cortical surface-based registration using Multimodal Surface Matching (Robinson et al., 2014), and non-parametric group analysis with the HCP Pipelines. 27 healthy normal volunteers participated in the study. They were instructed to look at a black and white random-dot patch presented on the screen. The patch was stationary (fixation block), moved smoothly (smooth tracking block) or moved in a stepwise manner (saccadic tracking block) along with a Lissajous trajectory in a given block (20 s). The 4 pursuit and 4 saccade blocks were randomly inserted after a fixation block during a single run. This run was repeated 4 times.

In the contrast of the smooth tracking and steady fixation, we found significant activation in most of cortical areas reported in previous studies (Krauzlis, 2004; Lancer & Trillenberg, 2008) and also deactivation in several cortical areas (denoted with hot/cold colors in Figure 1, respectively). A similar (de)activation map was obtained for the contrast of the saccadic tracking and steady fixation. The comparison between the two types of tracking revealed smooth tracking predominance in early visual areas, the middle temporal complex, superior parietal lobule and posterior cingulate region, and saccadic tracking predominance in many parietal and frontal regions including the frontal, premotor, and supplementary and cingulate eye fields (FEF, PEF, and SCEF; denoted with hot/cold colors in Figure 2, respectively). In the cerebellum, a significant superiority of Lobule VII or lower was observed for the saccadic tracking. Additionally, a significant correspondence between these tracking-related cortical activation areas and heavily myelinated regions was confirmed.

These results strongly support regional contributions of eye movement functions known from previous literatures and extend our knowledges of the whole-brain functional circuitry of the visuo-oculomotor systems with novel regional activities and dependence on different eye movements.

Attention: Visual ²

Perception: Visual ¹

Cortex

FUNCTIONAL MRI

Myelin

Perception

Sub-Cortical

Vision

Other - Eye Movement