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Visual sensitivity and internally driven attentional shifts
S238
Abstracts
recorded by fMRI. In the half trials, auditory warning cues were presented preceding to the presentation of target words or symbol strings. The bilateral fisiform gyrus, left superior temporal gyrus, supplementary motor area showed significantly stronger activation to the masked word stimuli compared to the masked symbol stimuli when warning stimuli were presented just before the target stimuli. In the trials without warning cue, these effects were not observed. Furthermore effective connectivity analysis revealed attentional modulation in the subliminal processing of word is represented by top-down signal from the left inferior frontal gyrus to the left superior temporal gyrus. Given that the left superior temporal cortex plays an important role for the grapheme to phoneme conversion, the attentional modulation has an effect on the indirect route in subliminal word reading. doi:10.1016/j.neures.2009.09.1341
P3-j06 Visual sensitivity and internally driven attentional shifts Noriko Yamagishi 1,2 , Stephen J. Anderson 3 , Mitsuo Kawato 2 1
NICT, Kyoto, Japan; 2 ATR Computational Neuroscience Labs, Kyoto, Japan; 3 Aston University, Birmingham, UK It is known that attentional shifts in response to external cues enhance sensitivity to visual stimuli. The role of “internally driven” shifts remains unclear. Here, we developed a novel paradigm in which observers were asked to monitor their internal attentional status, completing the necessary visual task only when they perceived their attentional focus to be maximal. Using method of constant stimuli, visual sensitivity was measured with: (1) “internally driven” (observer control) covert attentional shifts, where observers depressed a button to initiate stimulus presentation; and (2) “externally driven” (computer control) covert shifts, where the stimulus was presented automatically. The results showed that sensitivity is greatest for internally driven shifts. The reciprocal of latency (ms) for achieving maximal attentional focus in condition 1 obeys a Gaussian distribution, and can be adequately explained using the LATER model. We suggest that observers can monitor their internal readiness-level threshold, responding with improved performance once it is exceeded. doi:10.1016/j.neures.2009.09.1342
P3-j07 Neural substrates of the audio-visual temporal simultaneity perception: An fMRI study Mika Murase 1 , Hiroki C Tanabe 1 , Masamichi J Hayashi 1 , Takanori Kochiyama 2 , Norihiro Sadato 1 1
NIPS, Okazaki, Japan;
2
ATR, Kyoto, Japan
Perception of temporal order and simultaneity from different sensory signals is important to form a coherent percept of the environment. Present study was aimed to elucidate the functional role of the polymodal cortical areas in the conscious awareness of the cross-modal simultaneity. Our hypothesis was that the cross-modal repetitive suppression in the polymodal area codes the percept of the simultaneity. We adopted auditory-visual temporal discrimination tasks. During fMRI, subjects were required to report whether they felt two stimuli as simultaneous or not. The polymodal right posterior STS, IFG, and the left LPi showed significant suppression of the task-related activation during the sub-threshold condition when two signals felt as simultaneous, compared with that during the supra-threshold condition when felt as separated. This suppression was not observed when subjects did not participate in the discrimination task. These data suggest that the polysensory cortices play a key role in the conscious awareness of the audio-visual cross-modal simultaneity. doi:10.1016/j.neures.2009.09.1343
P3-j08 Visual-tactile cross-modal links in spatial selective attention: an MEG study Tetsuo Kida, Koji Inui, Emi Tanaka, Ryusuke Kakigi Dept. Integ. Physiol., Nat. Inst. for Physiol. Sci., Okazaki, Japan Our previous study has used magnetoencephalophy (MEG) to demonstrate neural correlates of the link from vision to touch as well as within-modal attention effect in touch. To investigate neural correlate of the link from touch to vision, we recorded MEG responses to visual stimuli when subjects directed attention to an electrocutaneous or visual stimulus presented randomly in the left or right space. A response around the occipito-temporal area (150 ms) to visual stimuli was significantly enhanced by within-modal, cross-modal and inter-modal attention. A response over frontal areas (200 ms) were enhanced by within-modal spatial and inter-modal attention, but not by cross-modal spatial attention. These results show that the modality link in spatial attention from touch to vision is represented by
neural activity around the extrastriate (or multimodal) area earlier than 200 ms after visual input. doi:10.1016/j.neures.2009.09.1344
P3-j09 Brain activation during processing of emotional valence as measured with near-infrared spectroscopy Sachiko Takahama 1,3,4 , Izumi Ohzawa 1,4 , Yoshichika Yoshioka 1,2,4 1
Grad. Sch. Frontier Biosci., Osaka Univ., Suita, Japan; 2 Immunol. Frontier Res. Ctr., Osaka Univ., Suita, Japan; 3 Kobe Advanced ICT Res. Ctr., NICT, Kobe, Japan; 4 CREST, JST, Kawaguchi, Japan
Near-infrared spectroscopy (NIRS) is widely used to non-invasively obtain a topographic distribution of the activated regions in the cerebral cortex by monitoring changes in the blood volume and oxygenation. We investigated the spatiotemporal characteristics of prefrontal activation during an emotional activation task wherein the participants passively viewed positive, negative, and neutral emotional pictures (taken from the International Affective Picture System, IAPS). NIRS signals, blood flow, and heart rate were simultaneously recorded. The results showed that a negative emotional picture significantly decreased the heart rate and facial blood flow as compared to positive and neutral stimuli. Moreover, the positive and negative stimuli led to a significantly decrease in deoxy-hemoglobin. The same results were not obtained for oxy-hemoglobin in some NIRS channels. These results indicate that the deoxy-hemoglobin should be used for emotional paradigms rather than oxy-hemoglobin. doi:10.1016/j.neures.2009.09.1345
P3-j10 The influence of choice and interstimulus interval in number comparison task Takeshi Aikawa 1 , Yousuke Ogata 1 , Takahiro Horaguchi 2 , Miyuki Yamamoto 1 1
Comprehensive Human Sci., Univ. of Tsukuba, Japan; 2 Ibaraki Prefectural University of Health Sciences, Center for Medical Sciences, Japan In number comparison task, it is known that the response time is shorter when the numerical distance between two digits is larger (the distance effect). We have previously shown that the response time was shorter when choosing larger numerals than smaller ones in this task (the choice effect). This time, using the same task, we investigated the influences of the change of interstimulus intervals (ISI) of the presentation of stimulus from 2 to 10 s in this task. Our result confirmed the effects of choice and distance. In addition, interaction of choice and distance effect was observed, i.e. in cases of small distance and choice, elongation of response time was facilitated. An interesting finding was that the choice effect disappeared with 8 s ISI, whereas the distance effect was observed in all ISIs. These results suggest that ISI may influence neural mechanism of choice in numerical processing. doi:10.1016/j.neures.2009.09.1346
P3-j11 Choice Effect Suppressed Distance Effect in number comparison task in brain activity Yousuke Ogata, Takahiro Horaguchi, Noriya Watanabe, Takeshi Aikawa, Miyuki Yamamoto Comprehensive Human Sci., Univ. of Tsukuba, Ibaraki, Japan Behavioral and neurophysiological studies of numerical comparison have shown “Distance Effect”; the smaller is the numerical distance between two digits, the longer the response time. We recently reported on “Choice Effect,” which showed longer response times, and higher activity in the parietal cortex, at the choice of smaller number than of larger number by NIRS study. We re-investigated Choice Effect by using fMRI. Response times showed both Choice and Distance Effects. However, fMRI result showed segregation between Distance and Choice Effects. In several cortical areas including right temporo-parietal region and left insular cortex, higher activation was observed at the choice of smaller digits than of larger ones, while no significant difference was observed that corresponded to Distance Effect. Our results suggested that the Distance Effect in brain activity that has been reported was observed only subjects were instructed to choose a larger digit. When subjects have to switch in choices, higher attention might be required, which may suppress Distance Effect. doi:10.1016/j.neures.2009.09.1347
Abstracts
recorded by fMRI. In the half trials, auditory warning cues were presented preceding to the presentation of target words or symbol strings. The bilateral fisiform gyrus, left superior temporal gyrus, supplementary motor area showed significantly stronger activation to the masked word stimuli compared to the masked symbol stimuli when warning stimuli were presented just before the target stimuli. In the trials without warning cue, these effects were not observed. Furthermore effective connectivity analysis revealed attentional modulation in the subliminal processing of word is represented by top-down signal from the left inferior frontal gyrus to the left superior temporal gyrus. Given that the left superior temporal cortex plays an important role for the grapheme to phoneme conversion, the attentional modulation has an effect on the indirect route in subliminal word reading. doi:10.1016/j.neures.2009.09.1341
P3-j06 Visual sensitivity and internally driven attentional shifts Noriko Yamagishi 1,2 , Stephen J. Anderson 3 , Mitsuo Kawato 2 1
NICT, Kyoto, Japan; 2 ATR Computational Neuroscience Labs, Kyoto, Japan; 3 Aston University, Birmingham, UK It is known that attentional shifts in response to external cues enhance sensitivity to visual stimuli. The role of “internally driven” shifts remains unclear. Here, we developed a novel paradigm in which observers were asked to monitor their internal attentional status, completing the necessary visual task only when they perceived their attentional focus to be maximal. Using method of constant stimuli, visual sensitivity was measured with: (1) “internally driven” (observer control) covert attentional shifts, where observers depressed a button to initiate stimulus presentation; and (2) “externally driven” (computer control) covert shifts, where the stimulus was presented automatically. The results showed that sensitivity is greatest for internally driven shifts. The reciprocal of latency (ms) for achieving maximal attentional focus in condition 1 obeys a Gaussian distribution, and can be adequately explained using the LATER model. We suggest that observers can monitor their internal readiness-level threshold, responding with improved performance once it is exceeded. doi:10.1016/j.neures.2009.09.1342
P3-j07 Neural substrates of the audio-visual temporal simultaneity perception: An fMRI study Mika Murase 1 , Hiroki C Tanabe 1 , Masamichi J Hayashi 1 , Takanori Kochiyama 2 , Norihiro Sadato 1 1
NIPS, Okazaki, Japan;
2
ATR, Kyoto, Japan
Perception of temporal order and simultaneity from different sensory signals is important to form a coherent percept of the environment. Present study was aimed to elucidate the functional role of the polymodal cortical areas in the conscious awareness of the cross-modal simultaneity. Our hypothesis was that the cross-modal repetitive suppression in the polymodal area codes the percept of the simultaneity. We adopted auditory-visual temporal discrimination tasks. During fMRI, subjects were required to report whether they felt two stimuli as simultaneous or not. The polymodal right posterior STS, IFG, and the left LPi showed significant suppression of the task-related activation during the sub-threshold condition when two signals felt as simultaneous, compared with that during the supra-threshold condition when felt as separated. This suppression was not observed when subjects did not participate in the discrimination task. These data suggest that the polysensory cortices play a key role in the conscious awareness of the audio-visual cross-modal simultaneity. doi:10.1016/j.neures.2009.09.1343
P3-j08 Visual-tactile cross-modal links in spatial selective attention: an MEG study Tetsuo Kida, Koji Inui, Emi Tanaka, Ryusuke Kakigi Dept. Integ. Physiol., Nat. Inst. for Physiol. Sci., Okazaki, Japan Our previous study has used magnetoencephalophy (MEG) to demonstrate neural correlates of the link from vision to touch as well as within-modal attention effect in touch. To investigate neural correlate of the link from touch to vision, we recorded MEG responses to visual stimuli when subjects directed attention to an electrocutaneous or visual stimulus presented randomly in the left or right space. A response around the occipito-temporal area (150 ms) to visual stimuli was significantly enhanced by within-modal, cross-modal and inter-modal attention. A response over frontal areas (200 ms) were enhanced by within-modal spatial and inter-modal attention, but not by cross-modal spatial attention. These results show that the modality link in spatial attention from touch to vision is represented by
neural activity around the extrastriate (or multimodal) area earlier than 200 ms after visual input. doi:10.1016/j.neures.2009.09.1344
P3-j09 Brain activation during processing of emotional valence as measured with near-infrared spectroscopy Sachiko Takahama 1,3,4 , Izumi Ohzawa 1,4 , Yoshichika Yoshioka 1,2,4 1
Grad. Sch. Frontier Biosci., Osaka Univ., Suita, Japan; 2 Immunol. Frontier Res. Ctr., Osaka Univ., Suita, Japan; 3 Kobe Advanced ICT Res. Ctr., NICT, Kobe, Japan; 4 CREST, JST, Kawaguchi, Japan
Near-infrared spectroscopy (NIRS) is widely used to non-invasively obtain a topographic distribution of the activated regions in the cerebral cortex by monitoring changes in the blood volume and oxygenation. We investigated the spatiotemporal characteristics of prefrontal activation during an emotional activation task wherein the participants passively viewed positive, negative, and neutral emotional pictures (taken from the International Affective Picture System, IAPS). NIRS signals, blood flow, and heart rate were simultaneously recorded. The results showed that a negative emotional picture significantly decreased the heart rate and facial blood flow as compared to positive and neutral stimuli. Moreover, the positive and negative stimuli led to a significantly decrease in deoxy-hemoglobin. The same results were not obtained for oxy-hemoglobin in some NIRS channels. These results indicate that the deoxy-hemoglobin should be used for emotional paradigms rather than oxy-hemoglobin. doi:10.1016/j.neures.2009.09.1345
P3-j10 The influence of choice and interstimulus interval in number comparison task Takeshi Aikawa 1 , Yousuke Ogata 1 , Takahiro Horaguchi 2 , Miyuki Yamamoto 1 1
Comprehensive Human Sci., Univ. of Tsukuba, Japan; 2 Ibaraki Prefectural University of Health Sciences, Center for Medical Sciences, Japan In number comparison task, it is known that the response time is shorter when the numerical distance between two digits is larger (the distance effect). We have previously shown that the response time was shorter when choosing larger numerals than smaller ones in this task (the choice effect). This time, using the same task, we investigated the influences of the change of interstimulus intervals (ISI) of the presentation of stimulus from 2 to 10 s in this task. Our result confirmed the effects of choice and distance. In addition, interaction of choice and distance effect was observed, i.e. in cases of small distance and choice, elongation of response time was facilitated. An interesting finding was that the choice effect disappeared with 8 s ISI, whereas the distance effect was observed in all ISIs. These results suggest that ISI may influence neural mechanism of choice in numerical processing. doi:10.1016/j.neures.2009.09.1346
P3-j11 Choice Effect Suppressed Distance Effect in number comparison task in brain activity Yousuke Ogata, Takahiro Horaguchi, Noriya Watanabe, Takeshi Aikawa, Miyuki Yamamoto Comprehensive Human Sci., Univ. of Tsukuba, Ibaraki, Japan Behavioral and neurophysiological studies of numerical comparison have shown “Distance Effect”; the smaller is the numerical distance between two digits, the longer the response time. We recently reported on “Choice Effect,” which showed longer response times, and higher activity in the parietal cortex, at the choice of smaller number than of larger number by NIRS study. We re-investigated Choice Effect by using fMRI. Response times showed both Choice and Distance Effects. However, fMRI result showed segregation between Distance and Choice Effects. In several cortical areas including right temporo-parietal region and left insular cortex, higher activation was observed at the choice of smaller digits than of larger ones, while no significant difference was observed that corresponded to Distance Effect. Our results suggested that the Distance Effect in brain activity that has been reported was observed only subjects were instructed to choose a larger digit. When subjects have to switch in choices, higher attention might be required, which may suppress Distance Effect. doi:10.1016/j.neures.2009.09.1347