Ke Zhou | IBP - Academia.edu (original) (raw)
Papers by Ke Zhou
Nature neuroscience, 2007
When two isoluminant colors alternate at frequencies of 25 Hz or higher, observers perceive only ... more When two isoluminant colors alternate at frequencies of 25 Hz or higher, observers perceive only one fused color. Chromatic flicker beyond the fusion frequency induces flicker adaptation in human observers and stimulates monkey V1 neurons. Here we use functional magnetic resonance imaging (fMRI) to show that many human visual cortical areas, with the exception of VO, can distinguish between fused chromatic flicker and its matched nonflickering control. This result supports the existence of significant intracortical temporal filtering of high-frequency chromatic information. The result also suggests that a considerable difference in cortical activation in many visual cortical areas does not necessarily lead to different conscious experiences.
Human brain mapping, 2011
As Chinese reading engages a different neural network from alphabetic language reading, we invest... more As Chinese reading engages a different neural network from alphabetic language reading, we investigate whether leftward lateralization of the arcuate fasciculus (AF), as observed in the Western population, is also present in the Chinese population and if it does, whether it is associated with better reading ability. Diffusion tensor tractography analysis on 75 Chinese subjects of three age groups (first graders, fourth graders, and college students) showed that 70–83% of them had leftward lateralization of the AF. The pattern of lateralization did not differ significantly among the three groups, suggesting that lateralization of the AF is formed at an early age and before one enters first grade. Among the first graders, who had just started to learn to read, subjects with strongly leftward lateralized AF scored significantly higher than those with other defined lateralization patterns in Chinese (P = 0.001) and English (P = 0.036) reading tasks. This association was not observed among the fourth graders and college students who were experienced Chinese readers. Among the fourth graders, females were found to obtain significantly higher Chinese (P = 0.033) and English reading scores than males (P = 0.002). Our study suggests a differential effect of leftward lateralization of the AF on reading ability at different stages of reading development in the Chinese population. Hum Brain Mapp, 2011. © 2011 Wiley Periodicals, Inc.
Proceedings of the National Academy of Sciences of the United States of America, 2010
Linguistic categories have been shown to influence perceptual discrimination, to do so preferenti... more Linguistic categories have been shown to influence perceptual discrimination, to do so preferentially in the right visual field, to fail to do so when competing demands are made on verbal memory, and to vary with the color-term boundaries of different languages. However, because there are strong commonalities across languages in the placement of color-term boundaries, the question remains open whether observed categorical perception for color can be entirely a result of learned categories or may rely to some degree on innate ones. We show here that lateralized color categorical perception can be entirely the result of learned categories. In a visual search task, reaction times to targets were faster in the right than the left visual field when the target and distractor colors, initially sharing the same linguistic term (e.g., "blue"), became between-category colors after training (i.e., when two different shades of blue had each acquired a new name). A control group, whose conditions exactly matched those of the experimental group except that no new categories were introduced, did not show this effect, establishing that the effect was not dependent on increased familiarity with either the color stimuli or the task. The present results show beyond question that lateralized categorical perception of color can reflect strictly learned color categories, even artificially learned categories that violate both universal tendencies in color naming and the categorization pattern of the language of the subject. category learning | Whorf hypothesis | nature versus nurture | linguistic relativity A long-standing "Whorfian" debate over the relation between language and thought has gained momentum in recent years with an increasing number of studies demonstrating the involvement of linguistic information in categorical perception of color (1-18).* For example, speakers of English judge colors that straddle the English category boundary between green and blue to be less similar than do speakers of Tarahumara, a Uto-Aztecan language of Mexico that uses a single word for these colors (1). Unlike English, Russian makes a distinction between lighter blues (goluboy) and darker blues (siniy), and Russian speakers are faster, compared with English speakers, in discriminating two colors when they fall into different categories, one goluboy and the other siniy, than when they belong to the same category (6).
Proceedings of the National Academy of Sciences of the United States of America, 2011
The human brain has been shown to exhibit changes in the volume and density of gray matter as a r... more The human brain has been shown to exhibit changes in the volume and density of gray matter as a result of training over periods of several weeks or longer. We show that these changes can be induced much faster by using a training method that is claimed to simulate the rapid learning of word meanings by children. Using whole-brain magnetic resonance imaging (MRI) we show that learning newly defined and named subcategories of the universal categories green and blue in a period of 2 h increases the volume of gray matter in V2/3 of the left visual cortex, a region known to mediate color vision. This pattern of findings demonstrates that the anatomical structure of the adult human brain can change very quickly, specifically during the acquisition of new, named categories. Also, prior behavioral and neuroimaging research has shown that differences between languages in the boundaries of named color categories influence the categorical perception of color, as assessed by judgments of relative similarity, by response time in alternative forced-choice tasks, and by visual search. Moreover, further behavioral studies (visual search) and brain imaging studies have suggested strongly that the categorical effect of language on color processing is left-lateralized, i.e., mediated by activity in the left cerebral hemisphere in adults (hence "lateralized Whorfian" effects). The present results appear to provide a structural basis in the brain for the behavioral and neurophysiologically observed indices of these Whorfian effects on color processing. neuro-plasticity | brain development | Whorf hypothesis | anatomy R esearch on the adult animal brain has demonstrated experience-induced cortical structural changes and the relevant time scales at the cellular and synaptic level (1-11). In normal human adults, neuroimaging studies have shown structural plasticity (indexed by gray matter changes) in response to the acquisition of a new skill obtained by training over periods ranging from weeks (12) to years (13-17). Although these findings in themselves constitute a challenge to the traditional view that the anatomical structure of the intact adult human cortex cannot be altered, the degree of structural plasticity at this macroscopic level remains unknown.
PloS one, 2011
Patients with left neglect were tested with ''chimeric'' figures composed of the right and left h... more Patients with left neglect were tested with ''chimeric'' figures composed of the right and left halves of two different objects. The connectivity relation was modulated between the two half figures. For some displays, the two chimeric halves were separated by a small gap, while in others, the separate halves were connected by a line segment. In line with previous reports, performance on reporting the left half improved when the chimera were separated; but when a line connected the two separated halves the advantage was lost. If the connecting line was broken, the performance was again enhanced. The results suggest an important role for connectedness in the representation of perceptual objects and in the distribution of attention in neglect.
Psychonomic bulletin & review, 2005
The aim of this research was to investigate the mechanisms underlying stimulus-driven attentional... more The aim of this research was to investigate the mechanisms underlying stimulus-driven attentional capture by feature changes in basic dimensions, and we chose color for the present investigation. In Experiment 1, participants searched for a target letter among colored disks containing distractor letters while a disk underwent color change. Although color change was irrelevant to the task and uninformative about the target position, we found a strong form of stimulus-driven attentional capture. Experiment 2 demonstrated that salient color discontinuity per se could not capture attention, ruling out the possibility that the capture effect we observed might be due to color discontinuity. In Experiment 3, we observed the capture effect by color change again in a more optimized experimental design. The present findings show that color change captures attention, supporting our view that dynamic feature changes can capture attention in a stimulus-driven manner.
Human brain mapping, 2012
Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TM... more Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TMS) studies has been obtained for the involvement of right ventral posterior parietal cortex (PPC) in exogenous orienting. However, the contribution of dorsal PPC to attentional orienting, particularly endogenous orienting, is still under debate. In an informative peripheral cueing paradigm, in which the exogenous and endogenous orienting can be studied in relative isolation within a single task, we applied TMS over sub-regions of dorsal PPC to explore their possible distinct involvement in exogenous and endogenous processes. We found that disruption of the left posterior intraparietal sulcus (pIPS) weakened the attentional effects of endogenous orienting, but did not affect exogenous processes. In addition, TMS applied over the right superior parietal lobule (SPL) resulted in an overall increase in reaction times. The present study provides the causal evidence that the left pIPS plays a crucial role in voluntary orienting of visual attention, while right SPL is involved in the processing of arousal and/or vigilance. Hum Brain Mapp 33:2477–2486, 2012. © 2011 Wiley Periodicals, Inc.
PloS one, 2012
Mounting psychophysical evidence suggests that early visual computations are sensitive to the top... more Mounting psychophysical evidence suggests that early visual computations are sensitive to the topological properties of stimuli, such as the determination of whether the object has a hole or not. Previous studies have demonstrated that the hole feature took some advantages during conscious perception. In this study, we investigate whether there exists a privileged processing for hole stimuli during unconscious perception. By applying a continuous flash suppression paradigm, the target was gradually introduced to one eye to compete against a flashed full contrast Mondrian pattern which was presented to the other eye. This method ensured that the target image was suppressed during the initial perceptual period. We compared the initial suppressed duration between the stimuli with and without the hole feature and found that hole stimuli required less time than no-hole stimuli to gain dominance against the identical suppression noise. These results suggest the hole feature could be processed in the absence of awareness, and there exists a privileged detection of hole stimuli during suppressed phase in the interocular rivalry.
Proceedings of the National Academy of Sciences of the United States of America, 2010
The question of what is a perceptual object is one of the most central and also controversial iss... more The question of what is a perceptual object is one of the most central and also controversial issues in cognitive science. According to the topological approach to perceptual organization, the core intuitive notion of an object-the holistic identity preserved over shapechanging transformations-may be characterized precisely as topological invariance. Here we show that, across a series of multipleobject tracking tasks, performance was not disrupted when the moving items underwent massive featural changes. However, performance was significantly impaired when the items changed their topological properties of holes, demonstrating that topological invariance constrains what counts as an object in the first place. Consistent with previous findings, fMRI studies indicated that the anterior temporal lobe may be involved in the formation of object representation defined by topological constraints. attention | object-based | global-first | topological definition of objects | topological transformation
Journal of cognitive neuroscience
& In a previous study, observed both space-and object-based components of visual selective attent... more & In a previous study, observed both space-and object-based components of visual selective attention. However, the mechanisms underlying these two components and the relationship between them are not well understood. In the present research, with a similar paradigm, these issues were addressed by manipulating cue validity. Behavioral results indicated the presence of both space-and object-based components under high cue validity, similar to the results of Egly et al.'s study. In addition, under low cue validity, the space-based component was absent, whereas the object-based component was maintained. Further eventrelated potential results demonstrated an object-based effect at a sensory level over the posterior areas of brain, and a spacebased effect over the anterior region. The present data suggest that the space-and object-based components reflect mainly voluntary and reflexive mechanisms, respectively. &
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi, 2002
PloS one, 2012
It is well known that emotion can modulate attentional processes. Previous studies have shown tha... more It is well known that emotion can modulate attentional processes. Previous studies have shown that even under restricted awareness, emotional facial expressions (especially threat-related) can guide the direction of spatial attention. However, it remains unclear whether emotional facial expressions under restricted awareness can affect temporal attention. To address this issue, we used a modified attentional blink (AB) paradigm in which masked (Experiment 1) or unmasked (Experiment 2) emotional faces (fearful or neutral) were presented before the AB sequence. We found that, in comparison with neutral faces, masked fearful faces significantly decreased the AB magnitude (Experiment 1), whereas unmasked fearful faces significantly increased the AB magnitude (Experiment 2). These results indicate that effects of emotional expression on the AB are modulated by the level of awareness.
Current biology : CB, 2013
Humans are remarkable at rapidly learning regularities through experience from a dynamic environm... more Humans are remarkable at rapidly learning regularities through experience from a dynamic environment . For example, long-lasting memories are formed even for auditory noise patterns after short, repeated exposure in an unsupervised manner . Although animal neurophysiological and human studies demonstrate adaptive cortical plasticity after sensory learning and memory formation, the mechanisms by which the auditory system extracts and encodes holistic patterns from random noise, which contains neither semantic labels nor prominent acoustic features to facilitate encoding, remains unknown. Here we combined magnetoencephalography (MEG) with psychophysics to address the issue. We demonstrate that the establishment of a reliable neuronal phase pattern in low-frequency (3-8 Hz) auditory cortical responses mirrors the noise memory formation process. Specifically, with repeated exposure, originally novel noise patterns are memorized, as reflected in behavior, and gradually produce robust phase responses in auditory cortex. Moreover, different memorized noises elicit distinguishable phase responses, suggesting their specificity to noise structure. The results indicate that the gradual establishment of low-frequency oscillatory phase patterns in auditory neuronal responses mediates the implicit learning process by which originally undifferentiated noises become new auditory objects.
Brain connectivity, 2012
Neuroimaging studies of professional athletic or musical training have demonstrated considerable ... more Neuroimaging studies of professional athletic or musical training have demonstrated considerable practicedependent plasticity in various brain structures, which may reflect distinct training demands. In the present study, structural and functional brain alterations were examined in professional badminton players and compared with healthy controls using magnetic resonance imaging (MRI) and resting-state functional MRI. Gray matter concentration (GMC) was assessed using voxel-based morphometry (VBM), and resting-brain functions were measured by amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity. Results showed that the athlete group had greater GMC and ALFF in the right and medial cerebellar regions, respectively. The athlete group also demonstrated smaller ALFF in the left superior parietal lobule and altered functional connectivity between the left superior parietal and frontal regions. These findings indicate that badminton expertise is associated with not only plastic structural changes in terms of enlarged gray matter density in the cerebellum, but also functional alterations in fronto-parietal connectivity. Such structural and functional alterations may reflect specific experiences of badminton training and practice, including high-capacity visuo-spatial processing and hand-eye coordination in addition to refined motor skills.
Neuroimage, 2008
Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusiv... more Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusivity and anisotropy changes of white matter from late childhood to young adulthood, and correlate quantitative diffusion indices with Chinese and English reading performance scores. Seventy-five normal healthy school going ethnic Chinese students and young adults of three age groups were recruited (group 1, n = 24, mean ± SD = 7.4 ± 0.3 years; group 2, n = 27, mean ± SD = 10.3 ± 0.5 years; group 3, n = 24, mean ± SD = 22.8 ± 2.3 years). DTI was performed with 3 mm isotropic resolution to cover the entire brain. Voxel-wise analysis was performed using Tract-Based Spatial Statistics (TBSS) to localize regions of white matter showing significant changes of fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivities between groups. We found increased FA and decreased MD with increasing age in regions of cerebellar white matter, right temporal white matter, and a large portion of the superior frontal and parietal white matter driven by both the reduction of radial diffusivity and axial diffusivity with the former to a greater extent. Changes were continual from late childhood to young adulthood. Findings were confirmed by region-of-interest analysis in specific white matter tracts. After controlling for the effect of age, significant correlation was found between diffusion indices of the anterior limb of the left internal capsule and Chinese reading score (p = 0.05), and of the corona radiata and English reading score (p = 0.026 and p = 0.029 for left and right, respectively). These DTI indices likely reflect the multiple biological processes that occur during brain development which provide the neural substrate for ongoing functional connectivity including for reading development.
Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TM... more Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TMS) studies has been obtained for the involvement of right ventral posterior parietal cortex (PPC) in exogenous orienting. However, the contribution of dorsal PPC to attentional orienting, particularly endogenous orienting, is still under debate. In an informative peripheral cueing paradigm, in which the exogenous and endogenous orienting can be studied in relative isolation within a single task, we applied TMS over sub-regions of dorsal PPC to explore their possible distinct involvement in exogenous and endogenous processes. We found that disruption of the left posterior intraparietal sulcus (pIPS) weakened the attentional effects of endogenous orienting, but did not affect exogenous processes. In addition, TMS applied over the right superior parietal lobule (SPL) resulted in an overall increase in reaction times. The present study provides the causal evidence that the left pIPS plays a crucial role in voluntary orienting of visual attention, while right SPL is involved in the processing of arousal and/or vigilance. Hum Brain Mapp 00:000-000,
Nature neuroscience, 2007
When two isoluminant colors alternate at frequencies of 25 Hz or higher, observers perceive only ... more When two isoluminant colors alternate at frequencies of 25 Hz or higher, observers perceive only one fused color. Chromatic flicker beyond the fusion frequency induces flicker adaptation in human observers and stimulates monkey V1 neurons. Here we use functional magnetic resonance imaging (fMRI) to show that many human visual cortical areas, with the exception of VO, can distinguish between fused chromatic flicker and its matched nonflickering control. This result supports the existence of significant intracortical temporal filtering of high-frequency chromatic information. The result also suggests that a considerable difference in cortical activation in many visual cortical areas does not necessarily lead to different conscious experiences.
Human brain mapping, 2011
As Chinese reading engages a different neural network from alphabetic language reading, we invest... more As Chinese reading engages a different neural network from alphabetic language reading, we investigate whether leftward lateralization of the arcuate fasciculus (AF), as observed in the Western population, is also present in the Chinese population and if it does, whether it is associated with better reading ability. Diffusion tensor tractography analysis on 75 Chinese subjects of three age groups (first graders, fourth graders, and college students) showed that 70–83% of them had leftward lateralization of the AF. The pattern of lateralization did not differ significantly among the three groups, suggesting that lateralization of the AF is formed at an early age and before one enters first grade. Among the first graders, who had just started to learn to read, subjects with strongly leftward lateralized AF scored significantly higher than those with other defined lateralization patterns in Chinese (P = 0.001) and English (P = 0.036) reading tasks. This association was not observed among the fourth graders and college students who were experienced Chinese readers. Among the fourth graders, females were found to obtain significantly higher Chinese (P = 0.033) and English reading scores than males (P = 0.002). Our study suggests a differential effect of leftward lateralization of the AF on reading ability at different stages of reading development in the Chinese population. Hum Brain Mapp, 2011. © 2011 Wiley Periodicals, Inc.
Proceedings of the National Academy of Sciences of the United States of America, 2010
Linguistic categories have been shown to influence perceptual discrimination, to do so preferenti... more Linguistic categories have been shown to influence perceptual discrimination, to do so preferentially in the right visual field, to fail to do so when competing demands are made on verbal memory, and to vary with the color-term boundaries of different languages. However, because there are strong commonalities across languages in the placement of color-term boundaries, the question remains open whether observed categorical perception for color can be entirely a result of learned categories or may rely to some degree on innate ones. We show here that lateralized color categorical perception can be entirely the result of learned categories. In a visual search task, reaction times to targets were faster in the right than the left visual field when the target and distractor colors, initially sharing the same linguistic term (e.g., "blue"), became between-category colors after training (i.e., when two different shades of blue had each acquired a new name). A control group, whose conditions exactly matched those of the experimental group except that no new categories were introduced, did not show this effect, establishing that the effect was not dependent on increased familiarity with either the color stimuli or the task. The present results show beyond question that lateralized categorical perception of color can reflect strictly learned color categories, even artificially learned categories that violate both universal tendencies in color naming and the categorization pattern of the language of the subject. category learning | Whorf hypothesis | nature versus nurture | linguistic relativity A long-standing "Whorfian" debate over the relation between language and thought has gained momentum in recent years with an increasing number of studies demonstrating the involvement of linguistic information in categorical perception of color (1-18).* For example, speakers of English judge colors that straddle the English category boundary between green and blue to be less similar than do speakers of Tarahumara, a Uto-Aztecan language of Mexico that uses a single word for these colors (1). Unlike English, Russian makes a distinction between lighter blues (goluboy) and darker blues (siniy), and Russian speakers are faster, compared with English speakers, in discriminating two colors when they fall into different categories, one goluboy and the other siniy, than when they belong to the same category (6).
Proceedings of the National Academy of Sciences of the United States of America, 2011
The human brain has been shown to exhibit changes in the volume and density of gray matter as a r... more The human brain has been shown to exhibit changes in the volume and density of gray matter as a result of training over periods of several weeks or longer. We show that these changes can be induced much faster by using a training method that is claimed to simulate the rapid learning of word meanings by children. Using whole-brain magnetic resonance imaging (MRI) we show that learning newly defined and named subcategories of the universal categories green and blue in a period of 2 h increases the volume of gray matter in V2/3 of the left visual cortex, a region known to mediate color vision. This pattern of findings demonstrates that the anatomical structure of the adult human brain can change very quickly, specifically during the acquisition of new, named categories. Also, prior behavioral and neuroimaging research has shown that differences between languages in the boundaries of named color categories influence the categorical perception of color, as assessed by judgments of relative similarity, by response time in alternative forced-choice tasks, and by visual search. Moreover, further behavioral studies (visual search) and brain imaging studies have suggested strongly that the categorical effect of language on color processing is left-lateralized, i.e., mediated by activity in the left cerebral hemisphere in adults (hence "lateralized Whorfian" effects). The present results appear to provide a structural basis in the brain for the behavioral and neurophysiologically observed indices of these Whorfian effects on color processing. neuro-plasticity | brain development | Whorf hypothesis | anatomy R esearch on the adult animal brain has demonstrated experience-induced cortical structural changes and the relevant time scales at the cellular and synaptic level (1-11). In normal human adults, neuroimaging studies have shown structural plasticity (indexed by gray matter changes) in response to the acquisition of a new skill obtained by training over periods ranging from weeks (12) to years (13-17). Although these findings in themselves constitute a challenge to the traditional view that the anatomical structure of the intact adult human cortex cannot be altered, the degree of structural plasticity at this macroscopic level remains unknown.
PloS one, 2011
Patients with left neglect were tested with ''chimeric'' figures composed of the right and left h... more Patients with left neglect were tested with ''chimeric'' figures composed of the right and left halves of two different objects. The connectivity relation was modulated between the two half figures. For some displays, the two chimeric halves were separated by a small gap, while in others, the separate halves were connected by a line segment. In line with previous reports, performance on reporting the left half improved when the chimera were separated; but when a line connected the two separated halves the advantage was lost. If the connecting line was broken, the performance was again enhanced. The results suggest an important role for connectedness in the representation of perceptual objects and in the distribution of attention in neglect.
Psychonomic bulletin & review, 2005
The aim of this research was to investigate the mechanisms underlying stimulus-driven attentional... more The aim of this research was to investigate the mechanisms underlying stimulus-driven attentional capture by feature changes in basic dimensions, and we chose color for the present investigation. In Experiment 1, participants searched for a target letter among colored disks containing distractor letters while a disk underwent color change. Although color change was irrelevant to the task and uninformative about the target position, we found a strong form of stimulus-driven attentional capture. Experiment 2 demonstrated that salient color discontinuity per se could not capture attention, ruling out the possibility that the capture effect we observed might be due to color discontinuity. In Experiment 3, we observed the capture effect by color change again in a more optimized experimental design. The present findings show that color change captures attention, supporting our view that dynamic feature changes can capture attention in a stimulus-driven manner.
Human brain mapping, 2012
Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TM... more Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TMS) studies has been obtained for the involvement of right ventral posterior parietal cortex (PPC) in exogenous orienting. However, the contribution of dorsal PPC to attentional orienting, particularly endogenous orienting, is still under debate. In an informative peripheral cueing paradigm, in which the exogenous and endogenous orienting can be studied in relative isolation within a single task, we applied TMS over sub-regions of dorsal PPC to explore their possible distinct involvement in exogenous and endogenous processes. We found that disruption of the left posterior intraparietal sulcus (pIPS) weakened the attentional effects of endogenous orienting, but did not affect exogenous processes. In addition, TMS applied over the right superior parietal lobule (SPL) resulted in an overall increase in reaction times. The present study provides the causal evidence that the left pIPS plays a crucial role in voluntary orienting of visual attention, while right SPL is involved in the processing of arousal and/or vigilance. Hum Brain Mapp 33:2477–2486, 2012. © 2011 Wiley Periodicals, Inc.
PloS one, 2012
Mounting psychophysical evidence suggests that early visual computations are sensitive to the top... more Mounting psychophysical evidence suggests that early visual computations are sensitive to the topological properties of stimuli, such as the determination of whether the object has a hole or not. Previous studies have demonstrated that the hole feature took some advantages during conscious perception. In this study, we investigate whether there exists a privileged processing for hole stimuli during unconscious perception. By applying a continuous flash suppression paradigm, the target was gradually introduced to one eye to compete against a flashed full contrast Mondrian pattern which was presented to the other eye. This method ensured that the target image was suppressed during the initial perceptual period. We compared the initial suppressed duration between the stimuli with and without the hole feature and found that hole stimuli required less time than no-hole stimuli to gain dominance against the identical suppression noise. These results suggest the hole feature could be processed in the absence of awareness, and there exists a privileged detection of hole stimuli during suppressed phase in the interocular rivalry.
Proceedings of the National Academy of Sciences of the United States of America, 2010
The question of what is a perceptual object is one of the most central and also controversial iss... more The question of what is a perceptual object is one of the most central and also controversial issues in cognitive science. According to the topological approach to perceptual organization, the core intuitive notion of an object-the holistic identity preserved over shapechanging transformations-may be characterized precisely as topological invariance. Here we show that, across a series of multipleobject tracking tasks, performance was not disrupted when the moving items underwent massive featural changes. However, performance was significantly impaired when the items changed their topological properties of holes, demonstrating that topological invariance constrains what counts as an object in the first place. Consistent with previous findings, fMRI studies indicated that the anterior temporal lobe may be involved in the formation of object representation defined by topological constraints. attention | object-based | global-first | topological definition of objects | topological transformation
Journal of cognitive neuroscience
& In a previous study, observed both space-and object-based components of visual selective attent... more & In a previous study, observed both space-and object-based components of visual selective attention. However, the mechanisms underlying these two components and the relationship between them are not well understood. In the present research, with a similar paradigm, these issues were addressed by manipulating cue validity. Behavioral results indicated the presence of both space-and object-based components under high cue validity, similar to the results of Egly et al.'s study. In addition, under low cue validity, the space-based component was absent, whereas the object-based component was maintained. Further eventrelated potential results demonstrated an object-based effect at a sensory level over the posterior areas of brain, and a spacebased effect over the anterior region. The present data suggest that the space-and object-based components reflect mainly voluntary and reflexive mechanisms, respectively. &
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi, 2002
PloS one, 2012
It is well known that emotion can modulate attentional processes. Previous studies have shown tha... more It is well known that emotion can modulate attentional processes. Previous studies have shown that even under restricted awareness, emotional facial expressions (especially threat-related) can guide the direction of spatial attention. However, it remains unclear whether emotional facial expressions under restricted awareness can affect temporal attention. To address this issue, we used a modified attentional blink (AB) paradigm in which masked (Experiment 1) or unmasked (Experiment 2) emotional faces (fearful or neutral) were presented before the AB sequence. We found that, in comparison with neutral faces, masked fearful faces significantly decreased the AB magnitude (Experiment 1), whereas unmasked fearful faces significantly increased the AB magnitude (Experiment 2). These results indicate that effects of emotional expression on the AB are modulated by the level of awareness.
Current biology : CB, 2013
Humans are remarkable at rapidly learning regularities through experience from a dynamic environm... more Humans are remarkable at rapidly learning regularities through experience from a dynamic environment . For example, long-lasting memories are formed even for auditory noise patterns after short, repeated exposure in an unsupervised manner . Although animal neurophysiological and human studies demonstrate adaptive cortical plasticity after sensory learning and memory formation, the mechanisms by which the auditory system extracts and encodes holistic patterns from random noise, which contains neither semantic labels nor prominent acoustic features to facilitate encoding, remains unknown. Here we combined magnetoencephalography (MEG) with psychophysics to address the issue. We demonstrate that the establishment of a reliable neuronal phase pattern in low-frequency (3-8 Hz) auditory cortical responses mirrors the noise memory formation process. Specifically, with repeated exposure, originally novel noise patterns are memorized, as reflected in behavior, and gradually produce robust phase responses in auditory cortex. Moreover, different memorized noises elicit distinguishable phase responses, suggesting their specificity to noise structure. The results indicate that the gradual establishment of low-frequency oscillatory phase patterns in auditory neuronal responses mediates the implicit learning process by which originally undifferentiated noises become new auditory objects.
Brain connectivity, 2012
Neuroimaging studies of professional athletic or musical training have demonstrated considerable ... more Neuroimaging studies of professional athletic or musical training have demonstrated considerable practicedependent plasticity in various brain structures, which may reflect distinct training demands. In the present study, structural and functional brain alterations were examined in professional badminton players and compared with healthy controls using magnetic resonance imaging (MRI) and resting-state functional MRI. Gray matter concentration (GMC) was assessed using voxel-based morphometry (VBM), and resting-brain functions were measured by amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity. Results showed that the athlete group had greater GMC and ALFF in the right and medial cerebellar regions, respectively. The athlete group also demonstrated smaller ALFF in the left superior parietal lobule and altered functional connectivity between the left superior parietal and frontal regions. These findings indicate that badminton expertise is associated with not only plastic structural changes in terms of enlarged gray matter density in the cerebellum, but also functional alterations in fronto-parietal connectivity. Such structural and functional alterations may reflect specific experiences of badminton training and practice, including high-capacity visuo-spatial processing and hand-eye coordination in addition to refined motor skills.
Neuroimage, 2008
Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusiv... more Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusivity and anisotropy changes of white matter from late childhood to young adulthood, and correlate quantitative diffusion indices with Chinese and English reading performance scores. Seventy-five normal healthy school going ethnic Chinese students and young adults of three age groups were recruited (group 1, n = 24, mean ± SD = 7.4 ± 0.3 years; group 2, n = 27, mean ± SD = 10.3 ± 0.5 years; group 3, n = 24, mean ± SD = 22.8 ± 2.3 years). DTI was performed with 3 mm isotropic resolution to cover the entire brain. Voxel-wise analysis was performed using Tract-Based Spatial Statistics (TBSS) to localize regions of white matter showing significant changes of fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivities between groups. We found increased FA and decreased MD with increasing age in regions of cerebellar white matter, right temporal white matter, and a large portion of the superior frontal and parietal white matter driven by both the reduction of radial diffusivity and axial diffusivity with the former to a greater extent. Changes were continual from late childhood to young adulthood. Findings were confirmed by region-of-interest analysis in specific white matter tracts. After controlling for the effect of age, significant correlation was found between diffusion indices of the anterior limb of the left internal capsule and Chinese reading score (p = 0.05), and of the corona radiata and English reading score (p = 0.026 and p = 0.029 for left and right, respectively). These DTI indices likely reflect the multiple biological processes that occur during brain development which provide the neural substrate for ongoing functional connectivity including for reading development.
Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TM... more Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimulation (TMS) studies has been obtained for the involvement of right ventral posterior parietal cortex (PPC) in exogenous orienting. However, the contribution of dorsal PPC to attentional orienting, particularly endogenous orienting, is still under debate. In an informative peripheral cueing paradigm, in which the exogenous and endogenous orienting can be studied in relative isolation within a single task, we applied TMS over sub-regions of dorsal PPC to explore their possible distinct involvement in exogenous and endogenous processes. We found that disruption of the left posterior intraparietal sulcus (pIPS) weakened the attentional effects of endogenous orienting, but did not affect exogenous processes. In addition, TMS applied over the right superior parietal lobule (SPL) resulted in an overall increase in reaction times. The present study provides the causal evidence that the left pIPS plays a crucial role in voluntary orienting of visual attention, while right SPL is involved in the processing of arousal and/or vigilance. Hum Brain Mapp 00:000-000,