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Nonlinear spatial integration of disparity signals in fine depth discrimination: from a mathematical model to a physiological model
S174
Abstracts
almost identical, the effective connectivity from V4 to V1 was larger during SC than PC. This result indicates that backward modulation from V4 to V1 plays a significant role to generate subjective color perception with Benham’s top. doi:10.1016/j.neures.2009.09.914
P2-h20 Increase of frontal delta activity related to perceptual switching Mayuko Okada 1 , Yumie Ono 2 , Atsushi Ishiyama 1 , Naoko Kasai 1 1 2
Department of Electrical Engineering and Bioscience, Waseda Univ, Japan; Department Physiol. and Neurosci. Kanagawa Dent. Col., Kanagawa, Japan
We studied spontaneous brain activity that relates to perceptual switching with presentation of the Necker cube or physical switching of two cubic figures, to determine the brain regions that correspond to perceptual switching regardless of internal or physical replacement of objects. We measured whole-head EEG in three conditions of: (1) presentation of Necker cube and button press immediately after perceptual switching, (2) presentation of two cubes in alternate shifts and button press immediately after the replacement, and (3) presentation of blank screen and self-paced button press. We extracted spontaneous EEG with the time points of button press for further analysis using Fourier transform. We observed enhanced delta wave activity (0.5–4 Hz) in the frontal region in all of the subjects both in condition 1 and condition 2, compared to that in condition 3. Our results revealed that both perceptual and physical switching increase frontal delta wave activity, suggesting that the activity might play an important role in perceptual switching. doi:10.1016/j.neures.2009.09.915
P2-i01 Nonlinear spatial integration of disparity signals in fine depth discrimination: from a mathematical model to a physiological model Kazuma Shimamoto, Takahiro Doi, Takahiro Okada, Ichiro Fujita Frontier Biosci, Osaka Univ, Toyonaka, Japan Stereoscopic depth perception improves when a reference target is presented beside a test target. We previously estimated how depth perception weighs and integrates disparity signals from various locations in the two targets, and developed a mathematical model based on this estimated “spatial weight”. This model assumed relative disparity between the test and reference targets was a priori. Here we present a physiology-oriented model that spatially integrates the disparity signals in V1 into signals supporting fine, relative depth perception. The new model nonlinearly combines outputs from model V1 neurons (binocular energy neurons), each of which detects absolute disparity at a different location. By selectively weighing the responses of the model V1 neurons, our new model could produce a psychophysical spatial weight similar to that of human subjects. As a result, we postulate that extrastriate cortices nonlinearly integrate spatially local signals from V1 neurons into relative-disparity signals in a manner similar to our model. doi:10.1016/j.neures.2009.09.916
P2-i02 Effect of memory color strength on P3 component Kae Nakajima, Tetsuto Minami, Shigeki Nakauchi Department of Information & Computer Sciences Toyohashi University of Technology, Japan This study aims to examine how the strength of memory colors affects the ERP, especially focusing on the P3 component. In experiment1, subjects were instructed to adjust the color of objects until they appeared to be of typical color. Individual typical colors of grapes, a banana, a man face, and a Coca Cola logo were measured. Experiment2 consisted of two visual oddball paradigms: one whose stimuli include typical color objects as a standard stimulus and the opponent color objects as a target stimulus and the other vice versa. During the experiment2, EEG was recorded from 64 electrodes. There are significant differences in dependency of the P3 component on typical (memory) color or opponent (non-memory) colors, and a face is suggested to be the most intensive among four stimuli. This is supporting the previous studies showing that the color vision of primates may be optimally designed in order to distinguish the change of complexion from the evolutional point of view. In conclusion, these results suggest that P3 component in an oddball task is affected by the strength of the memory color. doi:10.1016/j.neures.2009.09.917
P2-i03 Classifying ambiguous cognitive states to by binarization images using EEG analysis Yosuke Noritake, Tetsuto Minami, Shigeki Nakauchi Dept of Infor, Toyohashi University of Technology, Japan
The purpose of this study was to classify ambiguous states through a single-trial analysis. Subjects were presented with binarization images (BI) and original color images (CI) in a specific order (BI - CI - BI), and were instructed to judge by button press whether they recognized what the binarization image is or not. During the experiment, EEG was recorded from 19 electrodes. EEG signals were analyzed through a wavelet transform, and were calculated amplitude information and phase information. Using these features of the brain states, cognitive states were classified by SVM. The best classification accuracy was obtained when the beta band power was used. Additionally, the spatial and temporal distributions of the conversion matrix of SVM were analyzed from a neuroscience point of view. As a result, the region contributing the states-classification was the right temporal region from 100 to 500 ms, which is parallel to recent evidence suggesting that the beta band in the right temporal region from 100 to 500 ms is related to the cognitive processing of the visual image (Sehatpour et al., 2008). doi:10.1016/j.neures.2009.09.918
P2-i04 C. elegans mutants defective in high-alkaline pH avoidance Shigeki Sanehisa, Mayuki Fujiwara, Takashi Murayama, Ichiro Maruyama Okinawa Institute of Science and Technology, Japan Cellular and molecular bases underlying nociception of high alkaline pH still remains to be explored. C. elegans senses higher alkaline pH ranges than ∼pH 10.5 as a noxious stimulus. On an agar plate with a pH gradient, wild-type worms avoided higher pH regions, and moved toward lower pH ranges. To understand the molecular and cellular basis of the high-alkaline pH avoidance, we have screened mutants defective in high-alkaline pH avoidance from animals treated with ethylmethanesulfonate (EMS), using the plate assay. Among five mutants isolated that could not avoid the high-alkaline pH, three of them showed normal chemotaxis behaviors toward watersoluble attractants such as NaCl and mild-alkaline pH, as well as normal osmotic avoidance behaviors. We will discuss about molecules and neurons responsible for the nociception of high-alkaline pH. doi:10.1016/j.neures.2009.09.919
P2-i05 Cellular and molecular mechanism underlying C. elegans chemotaxis toward mild alkaline pH Takashi Murayama, Mayuki Fujiwara, Ichio Maruyama OIST, Okinawa Wild-type C. elegans is attracted to mild alkaline pH in environment. To investigate cellular and molecular modes underlying this chemosensory behavior, we have used agar plate assays with a linear pH gradient. Along pH gradients from pH 6.8 to 8.5, wild-type worms were attracted to higher pH regions, whereas mutants defective in ASE chemosensory neurons were not. It was found that pH shifts from low to high, but not from high to low, activated left-ASE (ASEL) when the neuronal activity was monitored with a voltage-sensitive fluorescent protein. ASEL-specific rescue of tax-4 improved the defect of the mutant in the chemotaxis, suggesting that TAX-2/TAX-4 cyclic-nucleotide gated channel is involved in the chemotaxis. When we searched candidate genes that regulate the TAX-2/TAX-4 channel by RNAi, knock-down of gcy-14, which encodes a cell-surface receptor-type guanylyl cyclase, impaired the chemotaxis toward mild alkaline pH. The gcy-14 gene is preferentially expressed in ASEL, and GCY-14 fused with GFP was localized to the tip of sensory endings, suggesting that GCY-14 acts as a sensor in ASEL for mild alkaline pH. doi:10.1016/j.neures.2009.09.920
P2-i06 In vivo calcium imaging of OFF-responding ASK chemosensory neurons in C. elegans Yusuke Ohba 1 , Tokumitsu Wakabayashi 2 , Yukihiro Kimura 2 , Yohichi Satoh 3 , Ryuzo Shingai 1 1
Graduate School of Engineering, Iwate University; 2 Faculty of Engineering, Iwate University; 3 Department of Anatomy, Iwate Medical University
Transformation of sensory signals into neural activity is a crucial first step of the sensory-motor transformation pathway in an animal, s nervous system. Chemosensory ASK neurons of the nematode Caenorhabditis elegans are involved in the worm, s chemotaxis behavior toward L-lysine, as well as the highly frequent backward movements upon transfer from a seeded to an unseeded environment. In ASK neurons, we expressed G-CaMP, a genetically encoded calcium sensor protein, and observed the intracellular calcium dynamics to see the properties of the neurons during sensory stimulation. The level of calcium in ASK neurons were strongly decreased after addition of L-lysine, and transiently increased upon stimulus removal, demonstrating the stimulus-ON/activity-OFF response reminiscent of activity in vertebrate retinal pho-
Abstracts
almost identical, the effective connectivity from V4 to V1 was larger during SC than PC. This result indicates that backward modulation from V4 to V1 plays a significant role to generate subjective color perception with Benham’s top. doi:10.1016/j.neures.2009.09.914
P2-h20 Increase of frontal delta activity related to perceptual switching Mayuko Okada 1 , Yumie Ono 2 , Atsushi Ishiyama 1 , Naoko Kasai 1 1 2
Department of Electrical Engineering and Bioscience, Waseda Univ, Japan; Department Physiol. and Neurosci. Kanagawa Dent. Col., Kanagawa, Japan
We studied spontaneous brain activity that relates to perceptual switching with presentation of the Necker cube or physical switching of two cubic figures, to determine the brain regions that correspond to perceptual switching regardless of internal or physical replacement of objects. We measured whole-head EEG in three conditions of: (1) presentation of Necker cube and button press immediately after perceptual switching, (2) presentation of two cubes in alternate shifts and button press immediately after the replacement, and (3) presentation of blank screen and self-paced button press. We extracted spontaneous EEG with the time points of button press for further analysis using Fourier transform. We observed enhanced delta wave activity (0.5–4 Hz) in the frontal region in all of the subjects both in condition 1 and condition 2, compared to that in condition 3. Our results revealed that both perceptual and physical switching increase frontal delta wave activity, suggesting that the activity might play an important role in perceptual switching. doi:10.1016/j.neures.2009.09.915
P2-i01 Nonlinear spatial integration of disparity signals in fine depth discrimination: from a mathematical model to a physiological model Kazuma Shimamoto, Takahiro Doi, Takahiro Okada, Ichiro Fujita Frontier Biosci, Osaka Univ, Toyonaka, Japan Stereoscopic depth perception improves when a reference target is presented beside a test target. We previously estimated how depth perception weighs and integrates disparity signals from various locations in the two targets, and developed a mathematical model based on this estimated “spatial weight”. This model assumed relative disparity between the test and reference targets was a priori. Here we present a physiology-oriented model that spatially integrates the disparity signals in V1 into signals supporting fine, relative depth perception. The new model nonlinearly combines outputs from model V1 neurons (binocular energy neurons), each of which detects absolute disparity at a different location. By selectively weighing the responses of the model V1 neurons, our new model could produce a psychophysical spatial weight similar to that of human subjects. As a result, we postulate that extrastriate cortices nonlinearly integrate spatially local signals from V1 neurons into relative-disparity signals in a manner similar to our model. doi:10.1016/j.neures.2009.09.916
P2-i02 Effect of memory color strength on P3 component Kae Nakajima, Tetsuto Minami, Shigeki Nakauchi Department of Information & Computer Sciences Toyohashi University of Technology, Japan This study aims to examine how the strength of memory colors affects the ERP, especially focusing on the P3 component. In experiment1, subjects were instructed to adjust the color of objects until they appeared to be of typical color. Individual typical colors of grapes, a banana, a man face, and a Coca Cola logo were measured. Experiment2 consisted of two visual oddball paradigms: one whose stimuli include typical color objects as a standard stimulus and the opponent color objects as a target stimulus and the other vice versa. During the experiment2, EEG was recorded from 64 electrodes. There are significant differences in dependency of the P3 component on typical (memory) color or opponent (non-memory) colors, and a face is suggested to be the most intensive among four stimuli. This is supporting the previous studies showing that the color vision of primates may be optimally designed in order to distinguish the change of complexion from the evolutional point of view. In conclusion, these results suggest that P3 component in an oddball task is affected by the strength of the memory color. doi:10.1016/j.neures.2009.09.917
P2-i03 Classifying ambiguous cognitive states to by binarization images using EEG analysis Yosuke Noritake, Tetsuto Minami, Shigeki Nakauchi Dept of Infor, Toyohashi University of Technology, Japan
The purpose of this study was to classify ambiguous states through a single-trial analysis. Subjects were presented with binarization images (BI) and original color images (CI) in a specific order (BI - CI - BI), and were instructed to judge by button press whether they recognized what the binarization image is or not. During the experiment, EEG was recorded from 19 electrodes. EEG signals were analyzed through a wavelet transform, and were calculated amplitude information and phase information. Using these features of the brain states, cognitive states were classified by SVM. The best classification accuracy was obtained when the beta band power was used. Additionally, the spatial and temporal distributions of the conversion matrix of SVM were analyzed from a neuroscience point of view. As a result, the region contributing the states-classification was the right temporal region from 100 to 500 ms, which is parallel to recent evidence suggesting that the beta band in the right temporal region from 100 to 500 ms is related to the cognitive processing of the visual image (Sehatpour et al., 2008). doi:10.1016/j.neures.2009.09.918
P2-i04 C. elegans mutants defective in high-alkaline pH avoidance Shigeki Sanehisa, Mayuki Fujiwara, Takashi Murayama, Ichiro Maruyama Okinawa Institute of Science and Technology, Japan Cellular and molecular bases underlying nociception of high alkaline pH still remains to be explored. C. elegans senses higher alkaline pH ranges than ∼pH 10.5 as a noxious stimulus. On an agar plate with a pH gradient, wild-type worms avoided higher pH regions, and moved toward lower pH ranges. To understand the molecular and cellular basis of the high-alkaline pH avoidance, we have screened mutants defective in high-alkaline pH avoidance from animals treated with ethylmethanesulfonate (EMS), using the plate assay. Among five mutants isolated that could not avoid the high-alkaline pH, three of them showed normal chemotaxis behaviors toward watersoluble attractants such as NaCl and mild-alkaline pH, as well as normal osmotic avoidance behaviors. We will discuss about molecules and neurons responsible for the nociception of high-alkaline pH. doi:10.1016/j.neures.2009.09.919
P2-i05 Cellular and molecular mechanism underlying C. elegans chemotaxis toward mild alkaline pH Takashi Murayama, Mayuki Fujiwara, Ichio Maruyama OIST, Okinawa Wild-type C. elegans is attracted to mild alkaline pH in environment. To investigate cellular and molecular modes underlying this chemosensory behavior, we have used agar plate assays with a linear pH gradient. Along pH gradients from pH 6.8 to 8.5, wild-type worms were attracted to higher pH regions, whereas mutants defective in ASE chemosensory neurons were not. It was found that pH shifts from low to high, but not from high to low, activated left-ASE (ASEL) when the neuronal activity was monitored with a voltage-sensitive fluorescent protein. ASEL-specific rescue of tax-4 improved the defect of the mutant in the chemotaxis, suggesting that TAX-2/TAX-4 cyclic-nucleotide gated channel is involved in the chemotaxis. When we searched candidate genes that regulate the TAX-2/TAX-4 channel by RNAi, knock-down of gcy-14, which encodes a cell-surface receptor-type guanylyl cyclase, impaired the chemotaxis toward mild alkaline pH. The gcy-14 gene is preferentially expressed in ASEL, and GCY-14 fused with GFP was localized to the tip of sensory endings, suggesting that GCY-14 acts as a sensor in ASEL for mild alkaline pH. doi:10.1016/j.neures.2009.09.920
P2-i06 In vivo calcium imaging of OFF-responding ASK chemosensory neurons in C. elegans Yusuke Ohba 1 , Tokumitsu Wakabayashi 2 , Yukihiro Kimura 2 , Yohichi Satoh 3 , Ryuzo Shingai 1 1
Graduate School of Engineering, Iwate University; 2 Faculty of Engineering, Iwate University; 3 Department of Anatomy, Iwate Medical University
Transformation of sensory signals into neural activity is a crucial first step of the sensory-motor transformation pathway in an animal, s nervous system. Chemosensory ASK neurons of the nematode Caenorhabditis elegans are involved in the worm, s chemotaxis behavior toward L-lysine, as well as the highly frequent backward movements upon transfer from a seeded to an unseeded environment. In ASK neurons, we expressed G-CaMP, a genetically encoded calcium sensor protein, and observed the intracellular calcium dynamics to see the properties of the neurons during sensory stimulation. The level of calcium in ASK neurons were strongly decreased after addition of L-lysine, and transiently increased upon stimulus removal, demonstrating the stimulus-ON/activity-OFF response reminiscent of activity in vertebrate retinal pho-