Recent studies

Alpha band oscillations as a clock for visual processing

 Alpha band oscillation, electrical oscillations at around 10 Hz, is widely known to be modulated by attention, but the specific mechanism the oscillation works for visual processing remains to be known. We are trying to prove the hypothesis that the alpha band oscillation works as a clock for visual processing. Typically, we utilize an illusion called motion induced spatial conflict, where illusory jitter is perceived at the same frequency as the alpha oscillation to study the causal relation between alpha oscillation and visual processing.

Reference

  • Minami, S., Amano, K. (2017): Illusory jitter perceived at the frequency of alpha oscillations, Current Biology 27 (15), 2344–2351.
  • Amano, K., Arnold, D., Takeda, T. & Johnston, A. (2008): Alpha band amplification during illusory jitter perception, Journal of Vision 8(10): article 3, 1-8.
  • Arnold DH,Johnston A. (2003): Motion-induced spatial conflict, Nature 425(6954), 181-4.

Neural causes of visual perception studied with manipulative techniques

 Conventional studies in systems neuroscience measure neural activities correlated with the parameters of sensory stimuli or with specific tasks. One of the problem of this correlational approach is the difficulty in dissociating neural causes of perception/task from the epiphenomena (results) of perception/task. To overcome the limitation, we utilize manipulative techniques such as decoded neurofeedback (using either fMRI or MEG) and transcranial alternating current stimulations (tACS). For example, we have recently found promising results in creating orientation-specific color perception using fMRI decoded neurofeedback. We are trying to find the neural responses causally relate to visual perception.

Reference

  • Cortese, A., Amano, K., Koizumi, A., Kawato, M. & Lau, H. (2016): Multivoxel neurofeedback selectively modulates confidence without changing perceptual performance, Nature Communications 7, Article number: 13669.
  • Koizumi, A., Amano, K., Cortese, A., Yoshida, W., Seymour, B.,Kawato, M. & Lau, H. (2016): Fear reduction without fear through reinforcement of neural activity that bypasses conscious exposure, Nature Human Behaviour 1, Article number: 0006.
  • Amano, K., Kawato M., Sasaki, Y., Watanabe, T. (2016): Learning to Associate Orientation with Color in Early Visual Areas by Associative Decoded fMRI Neurofeedback, Current Biology 26 (14), 1861–1866.    
  • Shibata K,Watanabe T,Sasaki Y,Kawato M., (2011): Perceptual learning incepted by decoded fMRI neurofeedback without stimulus presentation, Science 334(6061), 1413-5.    

Investigation of functional brain maps with high-resolution 7T fMRI

 We are equipped with a high resolution 7T-fMRI at CiNet. With this equipment, we are currently investigating some functional differences across cortical layers as well as visual field maps for certain stimulus features, which have not been elucidated even with electrophysiological methods.

Reference

  • Harvey BM, Klein BP, Petridou N, Dumoulin SO. (2013): Topographic representation of numerosity in the human parietal cortex, Science 341(6150), 1123-6.
  • Amano, K.,Wandell, B., Dumoulin, S. (2009): Visual field maps, population receptive field sizes, and visual field coverage in the human MT+ complex, Journal of Neurophysiology 102, 2704-2718.

White matter pathways involving with visual processing

 The human brain has many long-range connections throughout white matter,which are essential for communication across distant brain regions involving with visual processing. We are studying the trajectory and properties of human visual white matter pathways based on diffusion MRI and quantitative T1 apping data collected by using CiNet MRI system. We are further studying the relationship between white matter properties and other measurements (e.g. MEG or psychophysics) in order to understand the mechanisms of long-range information transmission in human visual system.

Reference

  • Takemura, H., Caiafa, C. F., Wandell, B. A., & Pestilli, F. (2016): Ensemble Tractography, PLoS Computational Biology, 12(2), e1004692.
  • Takemura, H., Rokem, A., Winawer, J., Yeatman, J. D., Wandell, B. A. & Pestilli, F. (2015): A major human white-matter pathway between dorsal and ventral visual cortex, Cerebral Cortex. [Epub Ahead of Print]

Neural mechanisms underlying synchronous perception

 Human receives sensory inputs from several organs such as vision, audition or touch. These sensory inputs are processed in parallel, but should be bound afterwards for the coherent perception of outer world. One of the crucial cues for binding is the coincidence of inputs. With combining psychophysics, MEG and fMRI, we study how the timing information is extracted from sensory inputs, and how the information is compared for the synchronous/asynchronous perception.

Reference

  • Amano, K., Qi, L., Terada, Y & Nishida, S. (2016): Neural correlates of the time marker for the perception of event timing, eNeuro 3(4), e0144-16.2016 1–17.
  • Amano, K., Johnston, A. & Nishida, S. (2007): Two mechanisms underlying the effect of angle of motion direction change on colour-motion asynchrony, Vision Research 47(5), 687-705.
  • Nishida S, Johnston A. (2002): Marker correspondence, not processing latency,determines temporal binding of visual attributes, Curr Biol. 12(5):359-68.