Kaoru Nashiro | University of Southern California (original) (raw)

Papers by Kaoru Nashiro

Applied Psychophysiology and Biofeedback

Previous research suggests that higher heart rate variability (HRV) is associated with better cog... more Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Applied Psychophysiology and Biofeedback

Previous research suggests that higher heart rate variability (HRV) is associated with better cog... more Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Acute stress robustly activates the brain’s noradrenergic system, the hub of which is the locus c... more Acute stress robustly activates the brain’s noradrenergic system, the hub of which is the locus coeruleus (LC). Recent studies have indicated that structural integrity of the LC, assessed through magnetic resonance imaging (MRI), is associated with better cognitive outcomes in later life. However, no studies have examined whether MRI-assessed LC integrity is related to arousal responses to acute stress in either younger or older adults, despite the LC’s documented role in promoting physiological arousal as part of the acute stress response. In this study, 102 younger and 51 older adults completed an acute stress induction task while we assessed multiple measures of physiological arousal (heart rate, breathing rate, systolic and diastolic blood pressure, sympathetic tone, and heart rate variability, HRV). We used turbo spin echo MRI scans to quantify LC MRI contrast as a measure of LC integrity. Using univariate and multivariate approaches, we assessed how LC MRI contrast was associa...

The Journal of Neuroscience, 2022

Experimental Aging Research, 2010

Cognition & Emotion, 2011

In a typical reversal-learning experiment, one learns stimulusÁoutcome contingencies that then sw... more In a typical reversal-learning experiment, one learns stimulusÁoutcome contingencies that then switch without warning. For instance, participants might have to repeatedly choose between two faces, one of which yields points whereas the other does not, with a reversal at some point in which face yields points. The current study examined age differences in the effects of outcome type on reversal learning. In the first experiment, the participants' task was either to select the person who would be in a better mood or to select the person who would yield more points. Reversals in which face was the correct option occurred several times. Older adults did worse in blocks in which the correct response was to select the person who would not be angry than in blocks in which the correct response was to select the person who would smile. Younger adults did not show a difference by emotional valence. In the second study, the negative condition was switched to have the same format as the positive condition (to select who will be angry). Again, older adults did worse with negative than positive outcomes, whereas younger adults did not show a difference by emotional valence. A third experiment replicated the lack of valence effects in younger adults with a harder probabilistic reversal-learning task. In the first two experiments, older adults performed about as well as younger adults in the positive conditions but performed worse in the negative conditions. These findings suggest that negative emotional outcomes selectively impair older adults' reversal learning.

The ability to change an established stimulus-behavior association based on feedback is critical ... more The ability to change an established stimulus-behavior association based on feedback is critical for adaptive social behaviors. This ability has been examined in reversal learning tasks, where participants first learn a stimulus-response association (e.g., select a particular object to get a reward), and then need to alter their response when reinforcement contingencies change. While substantial evidence demonstrates that the orbitofrontal cortex (OFC) is a critical region for reversal learning, previous studies have not distinguished reversal learning for emotional associations from neutral associations. The current study examined whether OFC plays similar roles in emotional vs. neutral reversal learning. The OFC showed greater activity during reversals of stimulus-outcome associations for negative outcomes than for neutral outcomes. Similar OFC activity was also observed during reversals involving positive outcomes. Furthermore, OFC activity is more inversely correlated with amygdala activity during negative reversals than during neutral reversals. Overall, our results indicate that the OFC is more activated by emotional than neutral reversal learning and that OFC's interactions with the amygdala are greater for negative than neutral reversal learning.

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared ... more Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also enhance brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. In this healthy cohort, the two conditions did not differentially affect anxiety, depression or mood. However, the Osc+ intervention increased low-frequency heart rate variability and increased brain oscillatory dynamics and functional connectivity in emotion-related resting-state networks. It also increased down-regulation...

Prior studies on emotion regulation identified a set of brain regions specialized for generating ... more Prior studies on emotion regulation identified a set of brain regions specialized for generating and controlling affect. Researchers generally agree that when up- and down-regulating emotion, control regions in the prefrontal cortex turn up or down activity in affect-generating areas. However, the assumption that turning up and down emotions produces opposite effects in the same affect-generating regions is untested. We call this assumption the 'affective dial hypothesis.' Our study tested this hypothesis by examining the overlap between the sets of regions activated during up-regulation and those deactivated during down-regulation in a large number of participants (N=105). We found that up- and down-regulation both recruit regulatory regions such as the inferior frontal gyrus and dorsal anterior cingulate gyrus but act on distinct affect-generating regions. While up-regulation increases BOLD signal in regions associated with emotion such as the amygdala, anterior insula, st...

Restorative neurology and neuroscience, 2017

Many studies are currently researching the effects of video games, particularly in the domain of ... more Many studies are currently researching the effects of video games, particularly in the domain of cognitive training. Great variability exists among video games however, and few studies have attempted to compare different types of video games. Little is known, for instance, about the cognitive processes or brain structures that underlie learning of different genres of video games. To examine the cognitive and neural underpinnings of two different types of game learning in order to evaluate their common and separate correlates, with the hopes of informing future intervention research. Participants (31 younger adults and 31 older adults) completed an extensive cognitive battery and played two different genres of video games, one action game and one strategy game, for 1.5 hours each. DTI scans were acquired for each participant, and regional fractional anisotropy (FA) values were extracted using the JHU atlas. Behavioral results indicated that better performance on tasks of working memo...

Neurobiology of aging, 2017

Correlations in activity across disparate brain regions during rest reveal functional networks in... more Correlations in activity across disparate brain regions during rest reveal functional networks in the brain. Although previous studies largely agree that there is an age-related decline in the "default mode network," how age affects other resting-state networks, such as emotion-related networks, is still controversial. Here we used a dual-regression approach to investigate age-related alterations in resting-state networks. The results revealed age-related disruptions in functional connectivity in all 5 identified cognitive networks, namely the default mode network, cognitive-auditory, cognitive-speech (or speech-related somatosensory), and right and left frontoparietal networks, whereas such age effects were not observed in the 3 identified emotion networks. In addition, we observed age-related decline in functional connectivity in 3 visual and 3 motor/visuospatial networks. Older adults showed greater functional connectivity in regions outside 4 out of the 5 identified co...

Psychophysiology, 2016

Overloading the capacity of visual attention can result in mistakenly combining the various featu... more Overloading the capacity of visual attention can result in mistakenly combining the various features of an object, that is, illusory conjunctions. We hypothesize that if the two hemispheres separately process visual information by splitting attention, connectivity of corpus callosum-a brain structure integrating the two hemispheres-would predict the degree of illusory conjunctions. In the current study, we assessed two types of illusory conjunctions using a memory-scanning paradigm; the features were either presented across the two opposite hemifields or within the same hemifield. Four objects, each with two visual features, were briefly presented together followed by a probe-recognition and a confidence rating for the recognition accuracy. MRI scans were also obtained. Results indicated that successful recollection during probe recognition was better for across hemifields conjunctions compared to within hemifield conjunctions, lending support to the bilateral advantage of the two h...

The Journal of Neuroscience, 2017

Growth hormone receptor deficiency (GHRD) results in short stature, enhanced insulin sensitivity,... more Growth hormone receptor deficiency (GHRD) results in short stature, enhanced insulin sensitivity, and low circulating levels of insulin and insulin-like growth factor 1 (IGF-1). Previous studies in mice and humans suggested that GHRD has protective effects against age-related diseases, including cancer and diabetes. Whereas GHRD mice show improved age-dependent cognitive performance, the effect of GHRD on human cognition remains unknown. Using MRI, we compared brain structure, function, and connectivity between 13 people with GHRD and 12 unaffected relatives. We assessed differences in white matter microstructural integrity, hippocampal volume, subregional volumes, and cortical thickness and surface area of selected regions. We also evaluated brain activity at rest and during a hippocampal-dependent pattern separation task. The GHRD group had larger surface areas in several frontal and cingulate regions and showed trends toward larger dentategyrusandCA1regionsofthehippocampus.Theyhadlowermeandiffusivityinthegenuofthecorpuscallosumandtheanteriorthalamic tracts. The GHRD group showed enhanced cognitive performance and greater task-related activation in frontal, parietal, and hippocampal regions compared with controls. Furthermore, they had greater functional synchronicity of activity between the precuneus and the rest of the default mode network at rest. The results suggest that, compared with controls, GHRD subjects have brain structure and function that are more consistent with those observed in younger adults reported in previous studies. Further investigation may lead to improved understanding of underlying mechanisms and could contribute to the identification of treatments for age-related cognitive deficits.

The American Journal of Psychology, 2011

Previous research suggests that associative memory declines in normal aging and is severely affec... more Previous research suggests that associative memory declines in normal aging and is severely affected by Alzheimer’s disease (AD); however, it is unclear whether and how this deficit can be minimized. The present study investigated whether emotional arousal enhances associative memory in healthy younger and older adults and patients with probable AD. We examined the effect of arousal on memory for item-location associations. Arousal enhanced memory for item location similarly across the three groups, while valence had no effect in any groups. Overall, our results suggest that arousal has beneficial effects on associative memory in healthy older adults and AD patients, as previously observed in younger adults.

Frontiers in human neuroscience, 2014

An emerging field of research focused on fluctuations in brain signals has provided evidence that... more An emerging field of research focused on fluctuations in brain signals has provided evidence that the complexity of those signals, as measured by entropy, conveys important information about network dynamics (e.g., local and distributed processing). While much research has focused on how neural complexity differs in populations with different age groups or clinical disorders, substantially less research has focused on the basic understanding of neural complexity in populations with young and healthy brain states. The present study used resting-state fMRI data from the Human Connectome Project (Van Essen et al., 2013) to test the extent that neural complexity in the BOLD signal, as measured by multiscale entropy (1) would differ from random noise, (2) would differ between four major resting-state networks previously associated with higher-order cognition, and (3) would be associated with the strength and extent of functional connectivity-a complementary method of estimating informati...

Applied Psychophysiology and Biofeedback

Previous research suggests that higher heart rate variability (HRV) is associated with better cog... more Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Applied Psychophysiology and Biofeedback

Previous research suggests that higher heart rate variability (HRV) is associated with better cog... more Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Acute stress robustly activates the brain’s noradrenergic system, the hub of which is the locus c... more Acute stress robustly activates the brain’s noradrenergic system, the hub of which is the locus coeruleus (LC). Recent studies have indicated that structural integrity of the LC, assessed through magnetic resonance imaging (MRI), is associated with better cognitive outcomes in later life. However, no studies have examined whether MRI-assessed LC integrity is related to arousal responses to acute stress in either younger or older adults, despite the LC’s documented role in promoting physiological arousal as part of the acute stress response. In this study, 102 younger and 51 older adults completed an acute stress induction task while we assessed multiple measures of physiological arousal (heart rate, breathing rate, systolic and diastolic blood pressure, sympathetic tone, and heart rate variability, HRV). We used turbo spin echo MRI scans to quantify LC MRI contrast as a measure of LC integrity. Using univariate and multivariate approaches, we assessed how LC MRI contrast was associa...

The Journal of Neuroscience, 2022

Experimental Aging Research, 2010

Cognition & Emotion, 2011

In a typical reversal-learning experiment, one learns stimulusÁoutcome contingencies that then sw... more In a typical reversal-learning experiment, one learns stimulusÁoutcome contingencies that then switch without warning. For instance, participants might have to repeatedly choose between two faces, one of which yields points whereas the other does not, with a reversal at some point in which face yields points. The current study examined age differences in the effects of outcome type on reversal learning. In the first experiment, the participants' task was either to select the person who would be in a better mood or to select the person who would yield more points. Reversals in which face was the correct option occurred several times. Older adults did worse in blocks in which the correct response was to select the person who would not be angry than in blocks in which the correct response was to select the person who would smile. Younger adults did not show a difference by emotional valence. In the second study, the negative condition was switched to have the same format as the positive condition (to select who will be angry). Again, older adults did worse with negative than positive outcomes, whereas younger adults did not show a difference by emotional valence. A third experiment replicated the lack of valence effects in younger adults with a harder probabilistic reversal-learning task. In the first two experiments, older adults performed about as well as younger adults in the positive conditions but performed worse in the negative conditions. These findings suggest that negative emotional outcomes selectively impair older adults' reversal learning.

The ability to change an established stimulus-behavior association based on feedback is critical ... more The ability to change an established stimulus-behavior association based on feedback is critical for adaptive social behaviors. This ability has been examined in reversal learning tasks, where participants first learn a stimulus-response association (e.g., select a particular object to get a reward), and then need to alter their response when reinforcement contingencies change. While substantial evidence demonstrates that the orbitofrontal cortex (OFC) is a critical region for reversal learning, previous studies have not distinguished reversal learning for emotional associations from neutral associations. The current study examined whether OFC plays similar roles in emotional vs. neutral reversal learning. The OFC showed greater activity during reversals of stimulus-outcome associations for negative outcomes than for neutral outcomes. Similar OFC activity was also observed during reversals involving positive outcomes. Furthermore, OFC activity is more inversely correlated with amygdala activity during negative reversals than during neutral reversals. Overall, our results indicate that the OFC is more activated by emotional than neutral reversal learning and that OFC's interactions with the amygdala are greater for negative than neutral reversal learning.

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared ... more Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also enhance brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. In this healthy cohort, the two conditions did not differentially affect anxiety, depression or mood. However, the Osc+ intervention increased low-frequency heart rate variability and increased brain oscillatory dynamics and functional connectivity in emotion-related resting-state networks. It also increased down-regulation...

Prior studies on emotion regulation identified a set of brain regions specialized for generating ... more Prior studies on emotion regulation identified a set of brain regions specialized for generating and controlling affect. Researchers generally agree that when up- and down-regulating emotion, control regions in the prefrontal cortex turn up or down activity in affect-generating areas. However, the assumption that turning up and down emotions produces opposite effects in the same affect-generating regions is untested. We call this assumption the 'affective dial hypothesis.' Our study tested this hypothesis by examining the overlap between the sets of regions activated during up-regulation and those deactivated during down-regulation in a large number of participants (N=105). We found that up- and down-regulation both recruit regulatory regions such as the inferior frontal gyrus and dorsal anterior cingulate gyrus but act on distinct affect-generating regions. While up-regulation increases BOLD signal in regions associated with emotion such as the amygdala, anterior insula, st...

Restorative neurology and neuroscience, 2017

Many studies are currently researching the effects of video games, particularly in the domain of ... more Many studies are currently researching the effects of video games, particularly in the domain of cognitive training. Great variability exists among video games however, and few studies have attempted to compare different types of video games. Little is known, for instance, about the cognitive processes or brain structures that underlie learning of different genres of video games. To examine the cognitive and neural underpinnings of two different types of game learning in order to evaluate their common and separate correlates, with the hopes of informing future intervention research. Participants (31 younger adults and 31 older adults) completed an extensive cognitive battery and played two different genres of video games, one action game and one strategy game, for 1.5 hours each. DTI scans were acquired for each participant, and regional fractional anisotropy (FA) values were extracted using the JHU atlas. Behavioral results indicated that better performance on tasks of working memo...

Neurobiology of aging, 2017

Correlations in activity across disparate brain regions during rest reveal functional networks in... more Correlations in activity across disparate brain regions during rest reveal functional networks in the brain. Although previous studies largely agree that there is an age-related decline in the "default mode network," how age affects other resting-state networks, such as emotion-related networks, is still controversial. Here we used a dual-regression approach to investigate age-related alterations in resting-state networks. The results revealed age-related disruptions in functional connectivity in all 5 identified cognitive networks, namely the default mode network, cognitive-auditory, cognitive-speech (or speech-related somatosensory), and right and left frontoparietal networks, whereas such age effects were not observed in the 3 identified emotion networks. In addition, we observed age-related decline in functional connectivity in 3 visual and 3 motor/visuospatial networks. Older adults showed greater functional connectivity in regions outside 4 out of the 5 identified co...

Psychophysiology, 2016

Overloading the capacity of visual attention can result in mistakenly combining the various featu... more Overloading the capacity of visual attention can result in mistakenly combining the various features of an object, that is, illusory conjunctions. We hypothesize that if the two hemispheres separately process visual information by splitting attention, connectivity of corpus callosum-a brain structure integrating the two hemispheres-would predict the degree of illusory conjunctions. In the current study, we assessed two types of illusory conjunctions using a memory-scanning paradigm; the features were either presented across the two opposite hemifields or within the same hemifield. Four objects, each with two visual features, were briefly presented together followed by a probe-recognition and a confidence rating for the recognition accuracy. MRI scans were also obtained. Results indicated that successful recollection during probe recognition was better for across hemifields conjunctions compared to within hemifield conjunctions, lending support to the bilateral advantage of the two h...

The Journal of Neuroscience, 2017

Growth hormone receptor deficiency (GHRD) results in short stature, enhanced insulin sensitivity,... more Growth hormone receptor deficiency (GHRD) results in short stature, enhanced insulin sensitivity, and low circulating levels of insulin and insulin-like growth factor 1 (IGF-1). Previous studies in mice and humans suggested that GHRD has protective effects against age-related diseases, including cancer and diabetes. Whereas GHRD mice show improved age-dependent cognitive performance, the effect of GHRD on human cognition remains unknown. Using MRI, we compared brain structure, function, and connectivity between 13 people with GHRD and 12 unaffected relatives. We assessed differences in white matter microstructural integrity, hippocampal volume, subregional volumes, and cortical thickness and surface area of selected regions. We also evaluated brain activity at rest and during a hippocampal-dependent pattern separation task. The GHRD group had larger surface areas in several frontal and cingulate regions and showed trends toward larger dentategyrusandCA1regionsofthehippocampus.Theyhadlowermeandiffusivityinthegenuofthecorpuscallosumandtheanteriorthalamic tracts. The GHRD group showed enhanced cognitive performance and greater task-related activation in frontal, parietal, and hippocampal regions compared with controls. Furthermore, they had greater functional synchronicity of activity between the precuneus and the rest of the default mode network at rest. The results suggest that, compared with controls, GHRD subjects have brain structure and function that are more consistent with those observed in younger adults reported in previous studies. Further investigation may lead to improved understanding of underlying mechanisms and could contribute to the identification of treatments for age-related cognitive deficits.

The American Journal of Psychology, 2011

Previous research suggests that associative memory declines in normal aging and is severely affec... more Previous research suggests that associative memory declines in normal aging and is severely affected by Alzheimer’s disease (AD); however, it is unclear whether and how this deficit can be minimized. The present study investigated whether emotional arousal enhances associative memory in healthy younger and older adults and patients with probable AD. We examined the effect of arousal on memory for item-location associations. Arousal enhanced memory for item location similarly across the three groups, while valence had no effect in any groups. Overall, our results suggest that arousal has beneficial effects on associative memory in healthy older adults and AD patients, as previously observed in younger adults.

Frontiers in human neuroscience, 2014

An emerging field of research focused on fluctuations in brain signals has provided evidence that... more An emerging field of research focused on fluctuations in brain signals has provided evidence that the complexity of those signals, as measured by entropy, conveys important information about network dynamics (e.g., local and distributed processing). While much research has focused on how neural complexity differs in populations with different age groups or clinical disorders, substantially less research has focused on the basic understanding of neural complexity in populations with young and healthy brain states. The present study used resting-state fMRI data from the Human Connectome Project (Van Essen et al., 2013) to test the extent that neural complexity in the BOLD signal, as measured by multiscale entropy (1) would differ from random noise, (2) would differ between four major resting-state networks previously associated with higher-order cognition, and (3) would be associated with the strength and extent of functional connectivity-a complementary method of estimating informati...