- Email: [email protected]
Mechanisms underlying selective responses to a combination of color and motion direction of neurons in V2 of macaque monkeys
Abstracts / Neuroscience Research 71S (2011) e108–e415
from different feature dimensions, we made a reaction-time visual search task in which a singleton target differed from distractors in either color, shape, or both dimensions was presented and monkey subjects (Macaca fusucata) were required to make a saccade to a singleton target. In this study, we evaluated the easiness of the target detection by measuring the saccade reaction times (time from stimulus presentation to saccade initiation) for each stimulus condition. We found that the median saccade latency was reduced when the target-defining dimension was changed from a single feature to multiple features. Importantly, the reduction of reaction times tended to be large when two stimulus conditions (color and shape singletons) that elicited similar reaction times were combined. On the other hand, it tended to be small when those that elicited quite different reaction times were combined. These results suggest that visual salience signals from each feature dimension inhibit each other according to the relative difference in their signal strengths. doi:10.1016/j.neures.2011.07.1127
P3-k07 Mechanisms underlying selective responses to a combination of color and motion direction of neurons in V2 of macaque monkeys Hiroshi Tamura , Kousuke Aratono, Hisashi Takada Lab for Cog. Neuro., Grad. Sch. Front. Bio., Osaka Univ, Toyonaka, Japan In the earlier part of the visual processing of primates, neurons are sensitive to single visual submodality, such as color, shape, or motion direction. At the level of V2, however, there are neurons selectively responsive to a combination of color and motion direction (Aratono and Tamura, Neuro 2010). To elucidate mechanisms that generate the combination-selective responses, we analyzed visual responses of 1047 neurons in V2 of analgesized macaque monkeys. First, we investigated the possibility that luminance-contour responsive neurons provide inputs to combination-selective neurons by presenting stimuli on the equiluminant background. We found that the incidence of neurons selective to the combination was lower in the equiluminant condition than otherwise. The results indicate that mechanisms that utilize luminance contrast border, such as inputs from neurons sensitive to motion of luminance contour, contribute to the generation of the combination-selective responses. However, small but a significant fraction of neurons were responsive to the combinations even under the equiluminant condition. A mechanism that generates the combination-selective responses under the equiluminant condition is an integration of non-directional colorselective inputs based on the motion-energy model. The motion-energy model requires time delay between inputs to generate an oblique profile on the x–t plane of the space-time receptive field. Therefore, next, we investigated distribution of onset latency of V2 neurons to color stimuli presented on the equiluminant background, and found that the latency distributed in a wide range (61-93 ms, 25-75% quantiles). Thus, an appropriate integration of these color inputs also can confer selectivity to a combination of stimulus color and direction on V2 neurons. From these results, we conclude that diverse mechanisms contribute to the generation of selective responses to a combination of color and motion direction. Research fund: KAKENHI (23135521). doi:10.1016/j.neures.2011.07.1128
P3-k08 Dynamic perceptual changes of joint angles in a phantom arm Nobuyuki Inui Grad. Sch. Edu. Naruto Univ. Edu., Naruto, Japan Contorted phantom limbs often form when sensory inputs are removed, but the brain mechanisms underlying their formation are poorly understood. We tracked the evolution of an experimental phantom arm as well as a phantom hand during ischemic anesthesia of the right upper arm. Here we show that if a limb is fully extended or flexed at a joint before and during anesthesia, the phantom limb is flexed or extended in the opposite direction. In the first study subjects showed perceived posture of their right arm and hand using the left arm and hand. If the arm and hand were fully extended before and during anesthesia, the final phantom was bent at the wrist and elbow, but if the arm and hand were fully flexed before and during anesthesia, the final phantom was extended at wrist and elbow. The final perceived position of the wrist was more changed than that of the elbow. In the second study, however, when the hand and arm were held straight before and during anesthesia, the final phantom was not changed at the wrist although the final phantom was bent at the elbow. Hence, no default posture existed for the phantom arm and hand. The final perceived posture may depend on the ini-
e259
tial and evolving sensory input during the block rather than the final sensory input. Sensory changes were monitored. In all subjects, impairment of largefiber cutaneous sensation began distally with von Frey thresholds increasing. These data suggest that changes in perceived position of the joints develop early when large-fiber cutaneous sensation is beginning to degrade. Research fund: KAKENHI (21500544). doi:10.1016/j.neures.2011.07.1129
P3-k09 Representations of the great toe and fused lesser toes in the primary somatosensory cortex Teruo Hashimoto 1 Iriki 1 1
, Kenichi Ueno 2 , Michio Tanaka 1 , Atsushi
RIKEN BSI Symbolic Cognitive Development 2 RIKEN BSI fMRI Support Unit
We performed behavioral experiments in which vibrotactile sensations were applied to all 5 toes; we found that test subjects had slight difficulty discriminating between adjacent lesser toes, but not between the lesser and great toe. Further, high-spatial-resolution neuroimaging data illustrated that the representations of the lesser toes overlap, while that of the great toe is distinct in the primary somatosensory cortex (SI). By contrast, each of the fingers had a distinct representation in the SI. Finally, single-unit electrophysiological data from area 3b of a monkey brain revealed the presence of fused toe representations, which supported the human neuroimaging data. Notably, we observed fusion of all 5 toe representations in the monkey SI, which stands in contrast to the distinct great toe representation observed for humans. doi:10.1016/j.neures.2011.07.1130
P3-k10 Neurons in the trigeminal main sensory nucleus respond to innocuous thermal stimulation of the tongue in rats Tomio Hayama Dept. of Molphol. Physiol. Sci., Fac. of Life Sci., Kumamoto University, Kumamoto, Japan It was previously shown that the dorsal portion of the trigeminal main sensory nucleus (Vp) contains neurons responsive to innocuous thermal stimulation of the tongue. Neuroanatomical studies combined with electrophysiological techniques suggested that the dorsal portion of the Vp was a new relay for tongue thermal sense; it receives input from the caudal subnucleus of the spinal trigeminal nucleus (SpVc), the primary nociceptive and thermal relay for the trigeminal field, and sends output to the relay for the tongue thermal sense in the thalamus (Hayama, in press). The present study examined physiological properties of neurons in the dorsal portion of the Vp responsive to cold (20 ◦ C) or warm (40 ◦ C) stimulation of the tongue in urethane-anesthetized rats. Spontaneous activity of neurons responsive to thermal stimulation was suppressed by warm stimuli but potentiated by cold stimuli, indicating they are cold neurons. Upon cold stimulation impulse frequencies of most of the neurons (8/10) rapidly increased, then decreased and gradually increased to steady state level, showing a clear suppressive phase. The remaining two neurons had both dynamic and static responses without a suppressive phase. Average impulse frequencies in the steady state were 15.7 ± 5.9 at 20 ◦ C and 0.1 ± 0.3 at 40 ◦ C (mean ± SD, n = 10). Thermal receptive fields were located on the anterior portion of the tongue ipsilateral to the recording side in five neurons. Responsiveness to other sensory modalities was examined in three of the five neurons. They did not respond to tactile stimulation but responded to both of nociceptive mechanical and nociceptive heat stimulation. The result indicates that response properties of thermosensitive neurons in the Vp are different from those in the SpVc. doi:10.1016/j.neures.2011.07.1131
P3-k11 Transgenic zebrafish expressing optimized channelrhodopsin in Rohon-Beard neurons: Escape behavior by light Keiko Umeda Dept Developmental Biology and Neuroscience, Tohoku Univ Grad Sch Life Sciences, Sendai, Japan One of channelrhodopsin variants, channelrhodopsin-wide receiver (ChRWR) has several advantages over wild-type in the membrane expression and photocurrent properties (Wang et al., 2009). Here we generated transgenic lines of zebrafish expressing ChRWR conditionally under regulation of Gal4/UAS system. Transposon donor plasmid containing UAS:ChRWR-EGFP construct is injected with transposase mRNA in the
from different feature dimensions, we made a reaction-time visual search task in which a singleton target differed from distractors in either color, shape, or both dimensions was presented and monkey subjects (Macaca fusucata) were required to make a saccade to a singleton target. In this study, we evaluated the easiness of the target detection by measuring the saccade reaction times (time from stimulus presentation to saccade initiation) for each stimulus condition. We found that the median saccade latency was reduced when the target-defining dimension was changed from a single feature to multiple features. Importantly, the reduction of reaction times tended to be large when two stimulus conditions (color and shape singletons) that elicited similar reaction times were combined. On the other hand, it tended to be small when those that elicited quite different reaction times were combined. These results suggest that visual salience signals from each feature dimension inhibit each other according to the relative difference in their signal strengths. doi:10.1016/j.neures.2011.07.1127
P3-k07 Mechanisms underlying selective responses to a combination of color and motion direction of neurons in V2 of macaque monkeys Hiroshi Tamura , Kousuke Aratono, Hisashi Takada Lab for Cog. Neuro., Grad. Sch. Front. Bio., Osaka Univ, Toyonaka, Japan In the earlier part of the visual processing of primates, neurons are sensitive to single visual submodality, such as color, shape, or motion direction. At the level of V2, however, there are neurons selectively responsive to a combination of color and motion direction (Aratono and Tamura, Neuro 2010). To elucidate mechanisms that generate the combination-selective responses, we analyzed visual responses of 1047 neurons in V2 of analgesized macaque monkeys. First, we investigated the possibility that luminance-contour responsive neurons provide inputs to combination-selective neurons by presenting stimuli on the equiluminant background. We found that the incidence of neurons selective to the combination was lower in the equiluminant condition than otherwise. The results indicate that mechanisms that utilize luminance contrast border, such as inputs from neurons sensitive to motion of luminance contour, contribute to the generation of the combination-selective responses. However, small but a significant fraction of neurons were responsive to the combinations even under the equiluminant condition. A mechanism that generates the combination-selective responses under the equiluminant condition is an integration of non-directional colorselective inputs based on the motion-energy model. The motion-energy model requires time delay between inputs to generate an oblique profile on the x–t plane of the space-time receptive field. Therefore, next, we investigated distribution of onset latency of V2 neurons to color stimuli presented on the equiluminant background, and found that the latency distributed in a wide range (61-93 ms, 25-75% quantiles). Thus, an appropriate integration of these color inputs also can confer selectivity to a combination of stimulus color and direction on V2 neurons. From these results, we conclude that diverse mechanisms contribute to the generation of selective responses to a combination of color and motion direction. Research fund: KAKENHI (23135521). doi:10.1016/j.neures.2011.07.1128
P3-k08 Dynamic perceptual changes of joint angles in a phantom arm Nobuyuki Inui Grad. Sch. Edu. Naruto Univ. Edu., Naruto, Japan Contorted phantom limbs often form when sensory inputs are removed, but the brain mechanisms underlying their formation are poorly understood. We tracked the evolution of an experimental phantom arm as well as a phantom hand during ischemic anesthesia of the right upper arm. Here we show that if a limb is fully extended or flexed at a joint before and during anesthesia, the phantom limb is flexed or extended in the opposite direction. In the first study subjects showed perceived posture of their right arm and hand using the left arm and hand. If the arm and hand were fully extended before and during anesthesia, the final phantom was bent at the wrist and elbow, but if the arm and hand were fully flexed before and during anesthesia, the final phantom was extended at wrist and elbow. The final perceived position of the wrist was more changed than that of the elbow. In the second study, however, when the hand and arm were held straight before and during anesthesia, the final phantom was not changed at the wrist although the final phantom was bent at the elbow. Hence, no default posture existed for the phantom arm and hand. The final perceived posture may depend on the ini-
e259
tial and evolving sensory input during the block rather than the final sensory input. Sensory changes were monitored. In all subjects, impairment of largefiber cutaneous sensation began distally with von Frey thresholds increasing. These data suggest that changes in perceived position of the joints develop early when large-fiber cutaneous sensation is beginning to degrade. Research fund: KAKENHI (21500544). doi:10.1016/j.neures.2011.07.1129
P3-k09 Representations of the great toe and fused lesser toes in the primary somatosensory cortex Teruo Hashimoto 1 Iriki 1 1
, Kenichi Ueno 2 , Michio Tanaka 1 , Atsushi
RIKEN BSI Symbolic Cognitive Development 2 RIKEN BSI fMRI Support Unit
We performed behavioral experiments in which vibrotactile sensations were applied to all 5 toes; we found that test subjects had slight difficulty discriminating between adjacent lesser toes, but not between the lesser and great toe. Further, high-spatial-resolution neuroimaging data illustrated that the representations of the lesser toes overlap, while that of the great toe is distinct in the primary somatosensory cortex (SI). By contrast, each of the fingers had a distinct representation in the SI. Finally, single-unit electrophysiological data from area 3b of a monkey brain revealed the presence of fused toe representations, which supported the human neuroimaging data. Notably, we observed fusion of all 5 toe representations in the monkey SI, which stands in contrast to the distinct great toe representation observed for humans. doi:10.1016/j.neures.2011.07.1130
P3-k10 Neurons in the trigeminal main sensory nucleus respond to innocuous thermal stimulation of the tongue in rats Tomio Hayama Dept. of Molphol. Physiol. Sci., Fac. of Life Sci., Kumamoto University, Kumamoto, Japan It was previously shown that the dorsal portion of the trigeminal main sensory nucleus (Vp) contains neurons responsive to innocuous thermal stimulation of the tongue. Neuroanatomical studies combined with electrophysiological techniques suggested that the dorsal portion of the Vp was a new relay for tongue thermal sense; it receives input from the caudal subnucleus of the spinal trigeminal nucleus (SpVc), the primary nociceptive and thermal relay for the trigeminal field, and sends output to the relay for the tongue thermal sense in the thalamus (Hayama, in press). The present study examined physiological properties of neurons in the dorsal portion of the Vp responsive to cold (20 ◦ C) or warm (40 ◦ C) stimulation of the tongue in urethane-anesthetized rats. Spontaneous activity of neurons responsive to thermal stimulation was suppressed by warm stimuli but potentiated by cold stimuli, indicating they are cold neurons. Upon cold stimulation impulse frequencies of most of the neurons (8/10) rapidly increased, then decreased and gradually increased to steady state level, showing a clear suppressive phase. The remaining two neurons had both dynamic and static responses without a suppressive phase. Average impulse frequencies in the steady state were 15.7 ± 5.9 at 20 ◦ C and 0.1 ± 0.3 at 40 ◦ C (mean ± SD, n = 10). Thermal receptive fields were located on the anterior portion of the tongue ipsilateral to the recording side in five neurons. Responsiveness to other sensory modalities was examined in three of the five neurons. They did not respond to tactile stimulation but responded to both of nociceptive mechanical and nociceptive heat stimulation. The result indicates that response properties of thermosensitive neurons in the Vp are different from those in the SpVc. doi:10.1016/j.neures.2011.07.1131
P3-k11 Transgenic zebrafish expressing optimized channelrhodopsin in Rohon-Beard neurons: Escape behavior by light Keiko Umeda Dept Developmental Biology and Neuroscience, Tohoku Univ Grad Sch Life Sciences, Sendai, Japan One of channelrhodopsin variants, channelrhodopsin-wide receiver (ChRWR) has several advantages over wild-type in the membrane expression and photocurrent properties (Wang et al., 2009). Here we generated transgenic lines of zebrafish expressing ChRWR conditionally under regulation of Gal4/UAS system. Transposon donor plasmid containing UAS:ChRWR-EGFP construct is injected with transposase mRNA in the