Ichiro Fujita - Academia.edu (original) (raw)
Papers by Ichiro Fujita
Proceedings of Annual Meeting of the Physiological Society of Japan Proceedings of Annual Meeting of the Physiological Society of Japan, 2008
PubMed, Nov 1, 2016
The ventral visual pathway projecting from the primary visual cortex to the visual temporal assoc... more The ventral visual pathway projecting from the primary visual cortex to the visual temporal association cortex processes shape, color, and material properties of objects as well as face and facial expression, and stereoscopic depth. The last decade has witnessed great advances in our understanding of how information is transformed at each transition between the stages along this pathway. Accumulating evidence also indicates that neurons in the later part of the pathway (e.g., area V4 and inferior temporal cortex) are causally involved in generating perception of shape, color, face, and fine stereoscopic depth.
Journal of Neurophysiology, Feb 1, 2001
Neurons in the monkey inferior temporal cortex (IT) have been shown to respond to shapes defined ... more Neurons in the monkey inferior temporal cortex (IT) have been shown to respond to shapes defined by luminance, texture, or motion. In the present study, we determined whether IT neurons respond to shapes defined solely by binocular disparity, and if so, whether signals of disparity and other visual cues to define shape converge on single IT neurons. We recorded extracellular activity from IT neurons while monkeys performed a fixation task. Among the neurons that responded to at least one of eight random-dot stereograms (RDSs) containing different disparity-defined shapes, 21% varied their responses to different RDSs. Responses of most of the neurons were positively correlated between two sets of RDSs, which consisted of different dot patterns but defined the same set of eight shapes, whereas responses to RDSs and their monocular images were not correlated. This indicates that the response modulation for the eight RDSs reflects selectivity for shapes (or their component contours) defined by disparity, although responses were also affected by dot patterns per se. Among the neurons that showed selectivity for shapes defined by luminance or disparity, 44% were activated by both cues. Responses of these neurons to luminance-defined shapes and those to disparitydefined shapes were often positively correlated to each other. Furthermore the stimulus rank, which was determined by the magnitude of responses to shapes, generally matched between these cues. The same held true between disparity and texture cues. The results suggest that the signals of disparity, luminance, and texture cues to define the shapes converge on a population of single IT neurons to produce the selectivity for shapes.
Journal of Vision, Aug 31, 2017
We report findings from both human fMRI (n = 35), and MEG (n = 10) experiments that tested neural... more We report findings from both human fMRI (n = 35), and MEG (n = 10) experiments that tested neural responses to dynamic ('local', acceleration) cues in biological motion. We measured fMRI responses (3T Siemens Trio, 1.5 mm3) to point-light stimuli that were degraded according to: 1. spatial coherency (intact, horizontally scrambled with vertical order retained, horizontally scrambled with vertical order inverted); 2. local motion (intact, constant velocity); and 3. temporal structure (intact, scrambled). Results from MVPA decoding analyses revealed surprising sensitivity of subcortical (non-visual) thalamic area ventral lateral nucleus (VLN) for discriminating local naturally-accelerating biological motion from constant velocity motion, in addition to a wide cortical network that extends dorsally through the IPS and ventrally, including the STS. Retaining the vertical order of the local trajectories resulted in higher accuracies than inverting it, but phase-randomization did not affect (discrimination) responses. In a separate experiment, different subjects were presented with the same stimuli while magnetic responses were measured using a 360 channel whole head MEG system (Neuromag 360, Elekta; 1000 Hz sampling frequency). Results revealed responses in much of the same cortical network identified using fMRI, peaking at 100-150 ms, and again at 350-500 ms after stimulus onset during which we also observed important functional differences with greater activity in hMT+, LO, and STS for structure-from-motion versus the local natural acceleration stimulus, and greater early (V1-V3) and IPS activity for the local natural acceleration versus constant velocity motion. We also observed activity along the medial surface by 200 ms. The fact that medial activity arrives distinctly following early cortical activity (100-150 ms), but before the 350-500 ms window suggests that the implication of thalamic VLN for biological motion perception observed with fMRI may have arisen from early cortical responses, but not higher order extrastriate cortex
Neuroscience Research Supplements, 1986
Thermosensitive neurons in the preoptic and anterior hypothalamus (PO/AH) have been generally rec... more Thermosensitive neurons in the preoptic and anterior hypothalamus (PO/AH) have been generally recognized as playing a principal role in the central control of thermoregulation. Our recent studies have demonstrated that a considerable number of PO/AH thermosensitive neurons change their activity in response to non-thermal stimuli such as local osmolality and blood pressure changes, and during non-thermal behaviors such as feeding, drinking and grooming. Since it has been suggest-
Cortex, Mar 1, 2021
We sought to understand the spatiotemporal characteristics of biological motion perception. We pr... more We sought to understand the spatiotemporal characteristics of biological motion perception. We presented observers with biological motion walkers that differed in terms of form coherence or kinematics (i.e., the presence or absence of natural acceleration). Participants were asked to discriminate the facing direction of the stimuli while their magnetoencephalographic responses were concurrently imaged. We found that two univariate response components can be observed around ~200 msec and ~650 msec post-stimulus onset, each engaging lateral-occipital and parietal cortex prior to temporal and frontal cortex. Moreover, while univariate responses show biological motion form-specificity only after 300 msec, multivariate patterns specific to form can be well discriminated from those for local cues as early as 100 msec after stimulus onset. By finally examining the representational similarity of fMRI and MEG patterned responses, we show that early responses to biological motion are most likely sourced to occipital cortex while later responses likely originate from extrastriate body areas.
NeuroImage, Jul 1, 2018
Using fMRI and multivariate analyses we sought to understand the neural representations of articu... more Using fMRI and multivariate analyses we sought to understand the neural representations of articulated body shape and local kinematics in biological motion. We show that in addition to a cortical network that includes areas identified previously for biological motion perception, including the posterior superior temporal sulcus, inferior frontal gyrus, and ventral body areas, the ventral lateral nucleus, a presumably motoric thalamic area is sensitive to both form and kinematic information in biological motion. Our findings suggest that biological motion perception is not achieved as an end-point of segregated cortical form and motion networks as often suggested, but instead involves earlier parts in the visual system including a subcortical network.
IEICE Technical Report; IEICE Tech. Rep., Feb 28, 2011
We studied latency of neuronal selectivity for facial expression by using face images consisting ... more We studied latency of neuronal selectivity for facial expression by using face images consisting of 3 different facial expressions. We recorded extracellular neuronal activity from awake, fixating monkeys and examined time course of selectivity for facial expression with a 50 ms sliding time window. A population of face-responsive neurons in the temporal cortex demonstrated selectivity latencies shorter than 100 ms, whereas only a few face-responsive neurons in the amygdala showed such short latencies. Keyword monkeys, extracellular recording, superior temporal sulcus, inferior temporal cortex 1. 序論 1.1. 表情認識の脳内メカニズム 顔から読み取ることのできる表情は相手の感情を 推測する手がかりとなり,社会的な生活を営む上で大 きな役割を果たしている.ヒトだけでなくサルも,さ まざまな表情をさまざまな異なる社会的状況で示すこ とから,表情がコミュニケーションの手段として使わ れていると考えられている [1]. サルを対象とした過去の電気生理学実験は,側頭葉 皮質高次視覚関連領野および扁桃体において,視覚呈 示された顔画像の表情に対して選択性をもつ神経細胞 の存在を明らかにした [2-7].これらの脳領域によって 構成される脳内ネットワークが表情の認識に関与して いると考えられる. 1.2. 側頭葉皮質と扁桃体の解剖学的投射関係 側頭葉皮質の前半部から扁桃体へは強い解剖学的 な投射がある [8-10].一方,扁桃体からは側頭葉皮質 を含む広範な視覚皮質へ向かっての投射がある [9,11]. これらの双方向性の投射関係(図 1)にもとづくと, 側頭葉皮質の神経細胞の活動は扁桃体の神経細胞の活 動に影響を与えることができるのと同時に,扁桃体の 神経細胞の活動も側頭葉皮質の神経細胞の活動に影響 を与える可能性がある. 図 1 大脳の左側面図 側頭葉皮質前半部(薄い灰 色)とその内側に位置する扁桃体(濃い灰色)には, 双方向性の解剖学的投射がある. 1.3. 本研究の目的 表情選択性細胞が存在する側頭葉皮質と扁桃体は, 双方向性の投射関係をもつ.したがって,どちらの脳 領域も他方の脳領域への表情選択性の入力源となりえ る.本研究は,側頭葉皮質と扁桃体のどちらの脳領域 で先に表情選択的反応があらわれてくるのかを調べる ことで,どちらの脳領域が表情選択性の起源であるか を検討した.過去の研究では,異なる研究グループが 異なる方法を用いて実験をおこなっているために直接 的な比較ができず,この点は明らかになっていない. 本研究では領野間の違いを公平に比較するため,同じ 被験体,同じ視覚刺激,同じ解析方法を用いた. 2. 方法 2 頭のニホンザル(Macaca fuscata)を実験に用いた. 実験中,サルは暗室内でモニターの中心に呈示される 点を注視する行動課題を遂行した.赤外線カメラシス テムを使ってサルの視線方向を計測した [12].顔画像 は,その中心が注視点と重なるようにして呈示した(図 2 左).各顔画像の呈示時間は 500 ミリ秒であった.記 録実験開始前に撮像した核磁気共鳴画像にもとづいて, 側頭葉皮質と扁桃体にタングステン微小電極を刺入し た(図 2 右).電極先端から細胞外電位を計測して単一 神経細胞の活動を記録した.側頭葉皮質における記録 領域は上側頭溝の上壁と下壁,および下側頭回であっ た.扁桃体における記録領域は主に外側核と基底核で
IEICE Technical Report; IEICE Tech. Rep., Dec 8, 2018
IEICE Technical Report; IEICE Tech. Rep., Nov 15, 2018
Journal of Vision, Aug 31, 2017
Journal of Vision, Aug 31, 2017
IEICE Technical Report; IEICE Tech. Rep., Mar 15, 2016
We studied spatial frequency tuning of face responsive neurons in the monkey temporal cortex. To ... more We studied spatial frequency tuning of face responsive neurons in the monkey temporal cortex. To examine whether face responsive neurons are tuned to image-based spatial frequency (cycles/image) or retina-based spatial frequency (cycles/deg), we recorded single unit activities extracellularly and analyzed visual responses to filtered face images of various sizes (deg/image). We assessed dependency of spatial frequency tuning on retinal image size, and found that the neurons as a whole were tuned to image-based spatial frequency rather than to retina-based spatial frequency. Keyword Monkey,Temporal cortex,Face responsive neuron,Spatial frequency filtering 1. 序論 1.1. 顔認識の神経基盤 顔の認識は社会的な生活を営む上で大きな役割を 果たしている.顔から読み取ることのできる情報 (誰 であるか,どのような表情か,どこを見ているのか, など )は,相手の心的状態を推測する手がかりとなり, 集団社会において次の行動を決定するために役立つ. マカカ属サルでは,側頭葉皮質の高次視覚関連領野が このような顔認識に重要な役割を果たすと考えられて いる.サルの側頭葉皮質では,数多くの研究から顔画 像に対して視覚反応を示す神経細胞 (顔画像反応性細 胞 )の存在が報告されており [1],また,これらの神経 細胞群への人工的な電気刺激によって,サルの顔画像 選択行動が影響を受けることも報告されている [2]. 1.2. 顔...
The Keio Journal of Medicine, 2002
土井泰次郎 藤田一郎 大阪大学大学院生命機能研究科 〒560-8531 大阪府豊中市待兼山町 1-3 E-mail: {tdoi,fujita}@bpe.es.osaka-u.ac.jp あらま... more 土井泰次郎 藤田一郎 大阪大学大学院生命機能研究科 〒560-8531 大阪府豊中市待兼山町 1-3 E-mail: {tdoi,fujita}@bpe.es.osaka-u.ac.jp あらまし 知覚に相関した神経活動を探るために,強制 2 択課題を用いて弁別閾値付近でのサルの知覚判断のゆ らぎとニューロン活動のゆらぎとの相関を調べる研究が多くなされている.しかし閾値付近では自覚的な知覚がな くとも弁別の成績が良いことがあるので,より直接的に知覚に相関した神経活動を求めるにはサルに検出課題をさ せる必要がある.そこで本研究ではサルに図形検出課題を訓練し,この課題を遂行中のサルの下側頭皮質からニュ ーロン活動を記録した.サルの刺激検出の成否とニューロン活動のトライアル間変動の相関を信号検出理論にもと づいて評価したところ,下側頭皮質のニューロン活動のゆらぎは刺激の検出の成否と有意に相関していた.この結 果は,下側頭皮質の神経活動が「刺激の形が見えている」というアウェアネスに関わっていることを示唆している. キーワード アウェアネス、検出課題、下側頭皮質
IEICE technical report. Neurocomputing, 2008
The perceived size of an object remains relatively stable despite changes in the size of retinal ... more The perceived size of an object remains relatively stable despite changes in the size of retinal images accompanying changes in distance from the observer. In this perceptual phenomenon (size constancy), the brain uses distance information for calibrating the perceived size. Binocular disparity provides a clue about distance. To examine interaction between binocular disparity and stimulus size information, we recorded neuronal responses in the macaque cortical are V4. Half of V4 cells showed significant interaction between the tunings for binocular disparity and size. This behavior of V4 cells was consistent with psychophysical performance of human observers. The results suggest that V4 cells contribute to size constancy. Keyword Monkey, Visual area, Binocular disparity, Size perception, Size constancy 1. 背景 1.1. 大きさ恒常性 ある物体までの距離が変化すると、その物体の網膜 投影像の大きさは変化する。しかし、ヒトはその物体 の大きさが一定であると知覚できる。この心理現象は 大きさ恒常性と呼ばれる [1]。物体の物理的な大きさを 知覚するためには、その物体が与える網膜投影像の大 きさに加え、物体までの距離が必要である。脳は物体 までの距離と、網膜投影像の...
Proceedings of Annual Meeting of the Physiological Society of Japan Proceedings of Annual Meeting of the Physiological Society of Japan, 2008
PubMed, Nov 1, 2016
The ventral visual pathway projecting from the primary visual cortex to the visual temporal assoc... more The ventral visual pathway projecting from the primary visual cortex to the visual temporal association cortex processes shape, color, and material properties of objects as well as face and facial expression, and stereoscopic depth. The last decade has witnessed great advances in our understanding of how information is transformed at each transition between the stages along this pathway. Accumulating evidence also indicates that neurons in the later part of the pathway (e.g., area V4 and inferior temporal cortex) are causally involved in generating perception of shape, color, face, and fine stereoscopic depth.
Journal of Neurophysiology, Feb 1, 2001
Neurons in the monkey inferior temporal cortex (IT) have been shown to respond to shapes defined ... more Neurons in the monkey inferior temporal cortex (IT) have been shown to respond to shapes defined by luminance, texture, or motion. In the present study, we determined whether IT neurons respond to shapes defined solely by binocular disparity, and if so, whether signals of disparity and other visual cues to define shape converge on single IT neurons. We recorded extracellular activity from IT neurons while monkeys performed a fixation task. Among the neurons that responded to at least one of eight random-dot stereograms (RDSs) containing different disparity-defined shapes, 21% varied their responses to different RDSs. Responses of most of the neurons were positively correlated between two sets of RDSs, which consisted of different dot patterns but defined the same set of eight shapes, whereas responses to RDSs and their monocular images were not correlated. This indicates that the response modulation for the eight RDSs reflects selectivity for shapes (or their component contours) defined by disparity, although responses were also affected by dot patterns per se. Among the neurons that showed selectivity for shapes defined by luminance or disparity, 44% were activated by both cues. Responses of these neurons to luminance-defined shapes and those to disparitydefined shapes were often positively correlated to each other. Furthermore the stimulus rank, which was determined by the magnitude of responses to shapes, generally matched between these cues. The same held true between disparity and texture cues. The results suggest that the signals of disparity, luminance, and texture cues to define the shapes converge on a population of single IT neurons to produce the selectivity for shapes.
Journal of Vision, Aug 31, 2017
We report findings from both human fMRI (n = 35), and MEG (n = 10) experiments that tested neural... more We report findings from both human fMRI (n = 35), and MEG (n = 10) experiments that tested neural responses to dynamic ('local', acceleration) cues in biological motion. We measured fMRI responses (3T Siemens Trio, 1.5 mm3) to point-light stimuli that were degraded according to: 1. spatial coherency (intact, horizontally scrambled with vertical order retained, horizontally scrambled with vertical order inverted); 2. local motion (intact, constant velocity); and 3. temporal structure (intact, scrambled). Results from MVPA decoding analyses revealed surprising sensitivity of subcortical (non-visual) thalamic area ventral lateral nucleus (VLN) for discriminating local naturally-accelerating biological motion from constant velocity motion, in addition to a wide cortical network that extends dorsally through the IPS and ventrally, including the STS. Retaining the vertical order of the local trajectories resulted in higher accuracies than inverting it, but phase-randomization did not affect (discrimination) responses. In a separate experiment, different subjects were presented with the same stimuli while magnetic responses were measured using a 360 channel whole head MEG system (Neuromag 360, Elekta; 1000 Hz sampling frequency). Results revealed responses in much of the same cortical network identified using fMRI, peaking at 100-150 ms, and again at 350-500 ms after stimulus onset during which we also observed important functional differences with greater activity in hMT+, LO, and STS for structure-from-motion versus the local natural acceleration stimulus, and greater early (V1-V3) and IPS activity for the local natural acceleration versus constant velocity motion. We also observed activity along the medial surface by 200 ms. The fact that medial activity arrives distinctly following early cortical activity (100-150 ms), but before the 350-500 ms window suggests that the implication of thalamic VLN for biological motion perception observed with fMRI may have arisen from early cortical responses, but not higher order extrastriate cortex
Neuroscience Research Supplements, 1986
Thermosensitive neurons in the preoptic and anterior hypothalamus (PO/AH) have been generally rec... more Thermosensitive neurons in the preoptic and anterior hypothalamus (PO/AH) have been generally recognized as playing a principal role in the central control of thermoregulation. Our recent studies have demonstrated that a considerable number of PO/AH thermosensitive neurons change their activity in response to non-thermal stimuli such as local osmolality and blood pressure changes, and during non-thermal behaviors such as feeding, drinking and grooming. Since it has been suggest-
Cortex, Mar 1, 2021
We sought to understand the spatiotemporal characteristics of biological motion perception. We pr... more We sought to understand the spatiotemporal characteristics of biological motion perception. We presented observers with biological motion walkers that differed in terms of form coherence or kinematics (i.e., the presence or absence of natural acceleration). Participants were asked to discriminate the facing direction of the stimuli while their magnetoencephalographic responses were concurrently imaged. We found that two univariate response components can be observed around ~200 msec and ~650 msec post-stimulus onset, each engaging lateral-occipital and parietal cortex prior to temporal and frontal cortex. Moreover, while univariate responses show biological motion form-specificity only after 300 msec, multivariate patterns specific to form can be well discriminated from those for local cues as early as 100 msec after stimulus onset. By finally examining the representational similarity of fMRI and MEG patterned responses, we show that early responses to biological motion are most likely sourced to occipital cortex while later responses likely originate from extrastriate body areas.
NeuroImage, Jul 1, 2018
Using fMRI and multivariate analyses we sought to understand the neural representations of articu... more Using fMRI and multivariate analyses we sought to understand the neural representations of articulated body shape and local kinematics in biological motion. We show that in addition to a cortical network that includes areas identified previously for biological motion perception, including the posterior superior temporal sulcus, inferior frontal gyrus, and ventral body areas, the ventral lateral nucleus, a presumably motoric thalamic area is sensitive to both form and kinematic information in biological motion. Our findings suggest that biological motion perception is not achieved as an end-point of segregated cortical form and motion networks as often suggested, but instead involves earlier parts in the visual system including a subcortical network.
IEICE Technical Report; IEICE Tech. Rep., Feb 28, 2011
We studied latency of neuronal selectivity for facial expression by using face images consisting ... more We studied latency of neuronal selectivity for facial expression by using face images consisting of 3 different facial expressions. We recorded extracellular neuronal activity from awake, fixating monkeys and examined time course of selectivity for facial expression with a 50 ms sliding time window. A population of face-responsive neurons in the temporal cortex demonstrated selectivity latencies shorter than 100 ms, whereas only a few face-responsive neurons in the amygdala showed such short latencies. Keyword monkeys, extracellular recording, superior temporal sulcus, inferior temporal cortex 1. 序論 1.1. 表情認識の脳内メカニズム 顔から読み取ることのできる表情は相手の感情を 推測する手がかりとなり,社会的な生活を営む上で大 きな役割を果たしている.ヒトだけでなくサルも,さ まざまな表情をさまざまな異なる社会的状況で示すこ とから,表情がコミュニケーションの手段として使わ れていると考えられている [1]. サルを対象とした過去の電気生理学実験は,側頭葉 皮質高次視覚関連領野および扁桃体において,視覚呈 示された顔画像の表情に対して選択性をもつ神経細胞 の存在を明らかにした [2-7].これらの脳領域によって 構成される脳内ネットワークが表情の認識に関与して いると考えられる. 1.2. 側頭葉皮質と扁桃体の解剖学的投射関係 側頭葉皮質の前半部から扁桃体へは強い解剖学的 な投射がある [8-10].一方,扁桃体からは側頭葉皮質 を含む広範な視覚皮質へ向かっての投射がある [9,11]. これらの双方向性の投射関係(図 1)にもとづくと, 側頭葉皮質の神経細胞の活動は扁桃体の神経細胞の活 動に影響を与えることができるのと同時に,扁桃体の 神経細胞の活動も側頭葉皮質の神経細胞の活動に影響 を与える可能性がある. 図 1 大脳の左側面図 側頭葉皮質前半部(薄い灰 色)とその内側に位置する扁桃体(濃い灰色)には, 双方向性の解剖学的投射がある. 1.3. 本研究の目的 表情選択性細胞が存在する側頭葉皮質と扁桃体は, 双方向性の投射関係をもつ.したがって,どちらの脳 領域も他方の脳領域への表情選択性の入力源となりえ る.本研究は,側頭葉皮質と扁桃体のどちらの脳領域 で先に表情選択的反応があらわれてくるのかを調べる ことで,どちらの脳領域が表情選択性の起源であるか を検討した.過去の研究では,異なる研究グループが 異なる方法を用いて実験をおこなっているために直接 的な比較ができず,この点は明らかになっていない. 本研究では領野間の違いを公平に比較するため,同じ 被験体,同じ視覚刺激,同じ解析方法を用いた. 2. 方法 2 頭のニホンザル(Macaca fuscata)を実験に用いた. 実験中,サルは暗室内でモニターの中心に呈示される 点を注視する行動課題を遂行した.赤外線カメラシス テムを使ってサルの視線方向を計測した [12].顔画像 は,その中心が注視点と重なるようにして呈示した(図 2 左).各顔画像の呈示時間は 500 ミリ秒であった.記 録実験開始前に撮像した核磁気共鳴画像にもとづいて, 側頭葉皮質と扁桃体にタングステン微小電極を刺入し た(図 2 右).電極先端から細胞外電位を計測して単一 神経細胞の活動を記録した.側頭葉皮質における記録 領域は上側頭溝の上壁と下壁,および下側頭回であっ た.扁桃体における記録領域は主に外側核と基底核で
IEICE Technical Report; IEICE Tech. Rep., Dec 8, 2018
IEICE Technical Report; IEICE Tech. Rep., Nov 15, 2018
Journal of Vision, Aug 31, 2017
Journal of Vision, Aug 31, 2017
IEICE Technical Report; IEICE Tech. Rep., Mar 15, 2016
We studied spatial frequency tuning of face responsive neurons in the monkey temporal cortex. To ... more We studied spatial frequency tuning of face responsive neurons in the monkey temporal cortex. To examine whether face responsive neurons are tuned to image-based spatial frequency (cycles/image) or retina-based spatial frequency (cycles/deg), we recorded single unit activities extracellularly and analyzed visual responses to filtered face images of various sizes (deg/image). We assessed dependency of spatial frequency tuning on retinal image size, and found that the neurons as a whole were tuned to image-based spatial frequency rather than to retina-based spatial frequency. Keyword Monkey,Temporal cortex,Face responsive neuron,Spatial frequency filtering 1. 序論 1.1. 顔認識の神経基盤 顔の認識は社会的な生活を営む上で大きな役割を 果たしている.顔から読み取ることのできる情報 (誰 であるか,どのような表情か,どこを見ているのか, など )は,相手の心的状態を推測する手がかりとなり, 集団社会において次の行動を決定するために役立つ. マカカ属サルでは,側頭葉皮質の高次視覚関連領野が このような顔認識に重要な役割を果たすと考えられて いる.サルの側頭葉皮質では,数多くの研究から顔画 像に対して視覚反応を示す神経細胞 (顔画像反応性細 胞 )の存在が報告されており [1],また,これらの神経 細胞群への人工的な電気刺激によって,サルの顔画像 選択行動が影響を受けることも報告されている [2]. 1.2. 顔...
The Keio Journal of Medicine, 2002
土井泰次郎 藤田一郎 大阪大学大学院生命機能研究科 〒560-8531 大阪府豊中市待兼山町 1-3 E-mail: {tdoi,fujita}@bpe.es.osaka-u.ac.jp あらま... more 土井泰次郎 藤田一郎 大阪大学大学院生命機能研究科 〒560-8531 大阪府豊中市待兼山町 1-3 E-mail: {tdoi,fujita}@bpe.es.osaka-u.ac.jp あらまし 知覚に相関した神経活動を探るために,強制 2 択課題を用いて弁別閾値付近でのサルの知覚判断のゆ らぎとニューロン活動のゆらぎとの相関を調べる研究が多くなされている.しかし閾値付近では自覚的な知覚がな くとも弁別の成績が良いことがあるので,より直接的に知覚に相関した神経活動を求めるにはサルに検出課題をさ せる必要がある.そこで本研究ではサルに図形検出課題を訓練し,この課題を遂行中のサルの下側頭皮質からニュ ーロン活動を記録した.サルの刺激検出の成否とニューロン活動のトライアル間変動の相関を信号検出理論にもと づいて評価したところ,下側頭皮質のニューロン活動のゆらぎは刺激の検出の成否と有意に相関していた.この結 果は,下側頭皮質の神経活動が「刺激の形が見えている」というアウェアネスに関わっていることを示唆している. キーワード アウェアネス、検出課題、下側頭皮質
IEICE technical report. Neurocomputing, 2008
The perceived size of an object remains relatively stable despite changes in the size of retinal ... more The perceived size of an object remains relatively stable despite changes in the size of retinal images accompanying changes in distance from the observer. In this perceptual phenomenon (size constancy), the brain uses distance information for calibrating the perceived size. Binocular disparity provides a clue about distance. To examine interaction between binocular disparity and stimulus size information, we recorded neuronal responses in the macaque cortical are V4. Half of V4 cells showed significant interaction between the tunings for binocular disparity and size. This behavior of V4 cells was consistent with psychophysical performance of human observers. The results suggest that V4 cells contribute to size constancy. Keyword Monkey, Visual area, Binocular disparity, Size perception, Size constancy 1. 背景 1.1. 大きさ恒常性 ある物体までの距離が変化すると、その物体の網膜 投影像の大きさは変化する。しかし、ヒトはその物体 の大きさが一定であると知覚できる。この心理現象は 大きさ恒常性と呼ばれる [1]。物体の物理的な大きさを 知覚するためには、その物体が与える網膜投影像の大 きさに加え、物体までの距離が必要である。脳は物体 までの距離と、網膜投影像の...