The current research examined whether fair consideration-a social norm that people inherently pre... more The current research examined whether fair consideration-a social norm that people inherently prefer to confirm-would modulate face recognition. Each neutral face was associated with fair or unfair offers via an economic decision task, the Ultimatum Game (UG) task. After the UG, participants were asked to identify the faces of proposers who made different offers. Enhanced memory was observed for fair-related compared to unfair-related faces. Furthermore, high trait anxiety was associated with reduced memory for fair-related faces. These results were further confirmed by signal detection theory. The current research provided initial evidence that people showed enhanced memory for faces that made fair offers from the economic decision task, and that high trait anxiety was associated with reduced fair-related memory. Possible neural mechanisms and the implication in economic and social situations have been discussed.
High Spatial Frequencies (HSF - conveying local information) may serve a critical role in visual ... more High Spatial Frequencies (HSF - conveying local information) may serve a critical role in visual consciousness. Despite an HSF bias during visual perception in autism, autistic individuals demonstrate impairments in face processing. Our aim was to investigate the respective role of HSF and Low Spatial Frequencies (LSF - conveying coarse information) on visual consciousness in autism. Thirty-two autistic adults and 35 typically developing (TD) controls performed an emotional attentional blink paradigm with spatially filtered distractors. TD participants showed reduced T2 accuracy (i.e., accuracy for the second target given the correct report of the first target T1) after unfiltered and HSF distractors compared to LSF distractors. In the autistic group, we observed lower T2 accuracy than controls after HSF and LSF distractors but not after unfiltered distractors. Results suggest the importance of HSF for visual consciousness in TD participants whereas, both LSF and HSF seem important ...
Cognitive, Affective, & Behavioral Neuroscience, 2021
The current experiment examined the effect of fair-related stimuli on attentional orienting and t... more The current experiment examined the effect of fair-related stimuli on attentional orienting and the role of cardiac vagal tone indexed by heart rate variability (HRV). Neutral faces were associated with fair and unfair offers in the Ultimatum Game (UG). After the UG, participants performed the spatial cueing task in which targets were preceded by face cues that made fair or unfair offers in the UG. Participants showed faster attentional engagement to fair-related stimuli, which was more pronounced in individuals with lower resting HRV-indexing reduced cardiac vagal tone. Also, people showed delayed attentional disengagement from fair-related stimuli, which was not correlated with HRV. The current research provided initial evidence that fair-related social information influences spatial attention, which is associated with cardiac vagal tone. These results provide further evidence that the difficulty in attentional control associated with reduced cardiac vagal tone may extend to a broader social and moral context.
Background Impairments in facial emotion recognition have been a hallmark of autism, which may co... more Background Impairments in facial emotion recognition have been a hallmark of autism, which may contribute to the difficulty in social engagement and interpersonal interaction. Impaired facial emotion recognition in autism could be partly due to the asymmetrical perceptual bias to High Spatial Frequencies (HSF) information observed during visual perception. While Low Spatial Frequencies (LSF) convey coarse information, which would be critical for a fast analysis and categorization of emotional faces, HSF convey local information, which may serve a critical role in visual consciousness. However, to our knowledge, the effect of HSF on visual consciousness in autism has not been specifically studied so far. Methods Thirty-three adult autistic participants and 35 typically developing (TD) control participants performed an emotional attentional blink paradigm. Participants had to identify and report two targets (happy faces, T1 and T2) embedded in a stream of distractors (angry faces). Th...
The current research examines whether trait anxiety is associated with negative interpretation bi... more The current research examines whether trait anxiety is associated with negative interpretation bias when resolving valence ambiguity of surprised faces. To further isolate the neuro-cognitive mechanism, we presented angry, happy, and surprised faces at broad spatial frequency (BSF), high spatial frequency (HSF), and low spatial frequency (LSF) and asked participants to determine the valence of each face. High trait anxiety was associated with more negative interpretations of BSF (i.e., intact) surprised faces. However, the modulation of trait anxiety on the negative interpretation of surprised faces disappeared at HSF and LSF. The current study provides evidence that trait anxiety modulates negative interpretations of BSF surprised faces. However, the negative interpretation of LSF surprised faces appears to be a robust default response that occurs regardless of individual differences in trait anxiety.
Deficits in facial emotion processing is a major characteristic of patients with panic disorder. ... more Deficits in facial emotion processing is a major characteristic of patients with panic disorder. It is known that visual stimuli with different spatial frequencies take distinct neural pathways. This study investigated facial emotion processing involving stimuli presented at broad, high, and low spatial frequencies in patients with panic disorder. Eighteen patients with panic disorder and 19 healthy controls were recruited. Seven event-related potential (ERP) components: (P100, N170, early posterior negativity (EPN); vertex positive potential (VPP), N250, P300; and late positive potential (LPP)) were evaluated while the participants looked at fearful and neutral facial stimuli presented at three spatial frequencies. When a fearful face was presented, panic disorder patients showed a significantly increased P100 amplitude in response to low spatial frequency compared to high spatial frequency; whereas healthy controls demonstrated significant broad spatial frequency dependent process...
Patients with schizophrenia present with dysfunction of the magnocellular pathway, which might im... more Patients with schizophrenia present with dysfunction of the magnocellular pathway, which might impair their early visual processing. We explored the relationship between functional abnormality of early visual processing and brain volumetric changes in schizophrenia. Eighteen patients and 16 healthy controls underwent electroencephalographic recordings and high-resolution magnetic resonance imaging. During electroencephalographic recordings, participants passively viewed neutral or fearful faces with broad, high, or low spatial frequency characteristics. Voxel-based morphometry was performed to investigate brain volume correlates of visual processing deficits. Event related potential analysis suggested that patients with schizophrenia had relatively impaired P100 processing of low spatial frequency fearful face stimuli compared with healthy controls; patients' gray-matter volumes in the dorsolateral and medial prefrontal cortices positively correlated with this amplitude. In addi...
Human faces automatically attract visual attention and this process appears to be guided by socia... more Human faces automatically attract visual attention and this process appears to be guided by social group memberships. In two experiments, we examined how social groups guide selective attention toward in-group and out-group faces. Black and White participants detected a target letter among letter strings superimposed on faces (Experiment 1). White participants were less accurate on trials with racial out-group (Black) compared to in-group (White) distractor faces. Likewise, Black participants were less accurate on trials with racial out-group (White) compared to in-group (Black) distractor faces. However, this pattern of out-group bias was only evident under high perceptual load-when the task was visually difficult. To examine the malleability of this pattern of racial bias, a separate sample of participants were assigned to mixed-race minimal groups (Experiment 2). Participants assigned to groups were less accurate on trials with their minimal in-group members compared to minimal out-group distractor faces, regardless of race. Again, this pattern of out-group bias was only evident under high perceptual load. Taken together, these results suggest that social identity guides selective attention toward motivationally relevant social groups-shifting from out-group bias in the domain of race to in-group bias in the domain of minimal groups-when perceptual resources are scarce.
From the heart to the mind's eye: Cardiac vagal tone is related to visual perception of fear... more From the heart to the mind's eye: Cardiac vagal tone is related to visual perception of fearful faces at high spatial frequency Gewn hi Park
Another gene associated with anxiety disorders is the Catechol-O-methyltransferase (COMT) genetic... more Another gene associated with anxiety disorders is the Catechol-O-methyltransferase (COMT) genetic variation (Funke et al., 2005). COMT is an enzyme that plays an important role in the metabolism of brain dopamine and norepinephrine (Gadow et al., 2009). The COMT gene can be found in chromosome 22q11 and contains several single nucleotide polymorphisms (SNPs) that are functionally important. For example, Val158Met (rs4680)-associated with encoding either valine (Val) or methionine (Met)-plays an important role in modulating COMT activity in the prefrontal cortex (Harrison et al., 2008). Current evidences suggest that Val158Met may be associated with anxiety disorders, particularly bipolar disorder, via controlling dopamine activity in the prefrontal cortex (Funke et al.,2005). Individuals with Val158 homozygous showed 35-50% higher COMT activity in human dorsolateral prefrontal cortex than those with Mel158 homozygous (Harrison et al., 2008). Although Met-COMT is considered to play an important role in the development of bipolar disorder, there exists evidence that Val-COMT is also associated with bipolar disorder (Funke et al., 2005). Lastly, the brain-derived neurotrophic factor (BDNF) gene variants are suggested to be linked with anxiety disorders (Chen et al., 2006; Gadow et al., 2009). BDNF is a neurotrophin that plays an important role in neuronal growth, differentiation, and synaptic plasticity (Chen et al., 2006; Gadow et al., 2009; Rasmusson et al., 2002). BDNF is also associated with learning and memory and modulates aggression (Rasmusson et al., 2002). It has been reported that BDNF plays a role in mediating effects of stress (Rasmusson et al., 2002). Reduced BDNF expression in the hippocampus was observed in response to stress, which may contribute to hippocampus-dependent memory deficits and the decreases in hippocampal volume associated with patients with post-traumatic stress disorder (PTSD; Rasmusson et al., 2002). Recent studies investigated the relationship between a SNP in the BDNF gene, Val66Met, and psychopathology, which yielded conflicting results (Jiang et al., 2005). In an animal study, when exposed to stress, BDNF Met/Met mice demonstrated anxiety-related behaviors and were not responsive to the antidepressant, fluoxetine (Chen et al., 2006). Studies showed that Val66 allele were associated with greater neuroticisim scores, suggesting that individuals with the Val allele may have increased risk for developing anxiety or depression (Hünnerkopf et al., 2007; Sen et al., 2003). However, no association between BDNF Val66Met genotypes and neuroticisim was observed in Asian female participants (Tsai et al., 2004). BDNF Met66 allele was found to be a risk allele for anxiety and depression (Jiang et al., 2005) whereas other found it to be a protective allele for obsessive-compulsive disorder (OCD; Hall et al., 2003). In sum, BDNF may be related to anxiety disorder though it is yet to be determined which specific variant is responsible for the pathogenesis of anxiety disorders (Gadow et al., 2009). So far, we have presented different candidate genetic marker of anxiety disorders. To have better understanding of anxiety disorders, it would be important to identify genetic polymorphisms associated with anxiety disorders and study together with psychophysiological markers which will be discussed later.
We examined whether cardiac vagal tone (indexed by heart rate variability: HRV) was associated wi... more We examined whether cardiac vagal tone (indexed by heart rate variability: HRV) was associated with the functioning of selective attention under load. Participants were instructed to detect a target letter among letter strings superimposed on either fearful or neutral distractor faces. Under low load, when letter strings consisted of six target letters, there was no difference between people with high and low HRV on task performance. Under high load, when letter strings consisted of one target letter and five non-target letters, people with high HRV were faster in trials with neutral distractors, but not with fearful distractors. However, people with low HRV were slower in trials with both fearful and neutral distractors. The current research suggests cardiac vagal tone is associated with successful control of selective attention critical for goaldirected behavior and its impact is greater when fewer cognitive resources are available.
We investigated gender differences in event-related potential (ERP) responses to subliminally pre... more We investigated gender differences in event-related potential (ERP) responses to subliminally presented threat-related stimuli. Twenty-four participants were presented with threat-related and neutral pictures for a very brief period of time (17 ms). To explore gender differences in ERP responses to subliminally presented stimuli, we examined six ERP components [P1, N170, N250, P300, Early Posterior Negativity (EPN) and Late Positive Potential (LPP)]. The result revealed that only female participants showed significant increases in the N170 and the EPN in response to subliminally presented threat-related stimuli compared to neutral stimuli. Our results suggest that female participants exhibit greater cortical processing of subliminally presented threat-related stimuli than male participants.
ketamine group when compared to saline (p=0.01 and p<0.01 respectively). While the two treatment ... more ketamine group when compared to saline (p=0.01 and p<0.01 respectively). While the two treatment groups did not differ in their reaction times to the task, accuracy in the ketamine group worsened significantly more with increase in task difficulty than in controls (F(1,42)=1.833, p =0.05). Ketamine also significantly increased the P1 amplitude in response to both encoding and retrieval stimuli (F(2,84)=4.66, p<0.05 and F(2,84)=4.2, p=0.05 respectively). CADSS but not BPRS was correlated with P1 amplitude at trend (R=0.27, p=0.08 and R=0.26, p=0.09 for encoding and retrieval respectively). There was also a decrease in P300 for encoding (F(2,84)=4.53, p<0.05) and retrieval (F(2,84)=3.00 p=0.09). The encoding P300 but not P1 amplitude correlated with percentage correct responses. Drug pretreatment did not affect power or PLF in the theta frequency band but they were correlated with the CADSS scores (R=0.37, p=0.1 and R=0.38, p=0.07, respectively). Discussion: In this study acute NMDA antagonism induced a WM deficit that was associated with visual processing abnormalities. Specifically, ketamine increased the amplitude of the P1 potential and the signal power and PLF of low frequency evoked oscillations which is contrary to the pattern observed in schizophrenia spectrum disorders. These effects could be mediated ketamine-induced acute glutamate release in the visual cortex, enhancing neuronal responses to visual stimuli. P300 amplitude was reduced in the ketamine group and this correlated with impaired WM performance accuracy. We speculate that impaired NMDA function accounts for the reduced P300 following ketamine and that this mimics the same abnormalities in schizophrenia.
We examined the relationship between tonic-a correlate of self-regulatory functioning-and phasic ... more We examined the relationship between tonic-a correlate of self-regulatory functioning-and phasic cardiac vagal activity (indexed by heart rate variability; HRV) during a selective attentional task with varying levels of load. Participants detected a target letter among letter strings superimposed on either fearful or neutral face distractors. Letter strings consisted of six target letters under low load and one target letter and five nontarget letters under high load. With fearful distractors, lower tonic HRV was associated with phasic HRV suppression, suggesting an autonomic stress response under both low and high load. In contrast, higher tonic HRV was associated with phasic HRV enhancement, suggesting greater self-regulatory effort under low load and an absence of phasic HRV suppression under high load. The current research suggests that tonic cardiac vagal tone is associated with the ability to flexibly adapt autonomic responses.
The current research examines individual differences in flexible emotional attention. In two expe... more The current research examines individual differences in flexible emotional attention. In two experiments, we investigated the relationship between individual differences in cardiac vagal tone and top-down and bottom-up processes associated with emotional attention. To help determine the role of cortical and subcortical mechanisms underlying top-down and bottom-up emotional attention, fearful faces at broad, high, and low spatial frequency were presented as cues that triggered either exogenous or endogenous orienting. Participants with lower heart rate variability (HRV) exhibited faster attentional engagement to low-spatial-frequency fearful faces at short stimulus-onset asynchronies, but showed delayed attentional disengagement from high-spatial-frequency fearful faces at long stimulus-onset asynchronies in contrast to participants with higher HRV. This research suggests that cardiac vagal tone is associated with more adaptive top-down and bottom-up modulation of emotional attention. Implications for various affective disorders, including depression, anxiety disorders, and posttraumatic stress disorder, are discussed.
proposes that individual differences in heart rate variability (HRV)-an index of cardiac vagal to... more proposes that individual differences in heart rate variability (HRV)-an index of cardiac vagal tone-are associated with attentional and emotional self-regulation. In this article, we demonstrate that individual differences in resting HRV predict the functioning of the inhibition of return (IOR), an inhibitory attentional mechanism highly adaptive to novelty search, in response to affectively significant face cues. As predicted, participants with lower HRV exhibited a smaller IOR effect to fearful versus neutral face cues than participants with higher HRV, which shows a failure to inhibit attention from affectively significant cues and instigate novelty search. In contrast, participants with higher HRV exhibited similar IOR effects to fearful and neutral face cues, which shows an ability to inhibit attention from cues and instigate novelty search. Their ability to inhibit attention was most pronounced to high spatial frequency fearful face cues, suggesting that this effect may be mediated by cortical mechanisms. The current research demonstrates that individual differences in HRV predict attentional inhibition and suggests that successful inhibition and novelty search may be mediated by cortical inhibitory mechanisms among people with high cardiac vagal tone.
The current research examined whether fair consideration-a social norm that people inherently pre... more The current research examined whether fair consideration-a social norm that people inherently prefer to confirm-would modulate face recognition. Each neutral face was associated with fair or unfair offers via an economic decision task, the Ultimatum Game (UG) task. After the UG, participants were asked to identify the faces of proposers who made different offers. Enhanced memory was observed for fair-related compared to unfair-related faces. Furthermore, high trait anxiety was associated with reduced memory for fair-related faces. These results were further confirmed by signal detection theory. The current research provided initial evidence that people showed enhanced memory for faces that made fair offers from the economic decision task, and that high trait anxiety was associated with reduced fair-related memory. Possible neural mechanisms and the implication in economic and social situations have been discussed.
High Spatial Frequencies (HSF - conveying local information) may serve a critical role in visual ... more High Spatial Frequencies (HSF - conveying local information) may serve a critical role in visual consciousness. Despite an HSF bias during visual perception in autism, autistic individuals demonstrate impairments in face processing. Our aim was to investigate the respective role of HSF and Low Spatial Frequencies (LSF - conveying coarse information) on visual consciousness in autism. Thirty-two autistic adults and 35 typically developing (TD) controls performed an emotional attentional blink paradigm with spatially filtered distractors. TD participants showed reduced T2 accuracy (i.e., accuracy for the second target given the correct report of the first target T1) after unfiltered and HSF distractors compared to LSF distractors. In the autistic group, we observed lower T2 accuracy than controls after HSF and LSF distractors but not after unfiltered distractors. Results suggest the importance of HSF for visual consciousness in TD participants whereas, both LSF and HSF seem important ...
Cognitive, Affective, & Behavioral Neuroscience, 2021
The current experiment examined the effect of fair-related stimuli on attentional orienting and t... more The current experiment examined the effect of fair-related stimuli on attentional orienting and the role of cardiac vagal tone indexed by heart rate variability (HRV). Neutral faces were associated with fair and unfair offers in the Ultimatum Game (UG). After the UG, participants performed the spatial cueing task in which targets were preceded by face cues that made fair or unfair offers in the UG. Participants showed faster attentional engagement to fair-related stimuli, which was more pronounced in individuals with lower resting HRV-indexing reduced cardiac vagal tone. Also, people showed delayed attentional disengagement from fair-related stimuli, which was not correlated with HRV. The current research provided initial evidence that fair-related social information influences spatial attention, which is associated with cardiac vagal tone. These results provide further evidence that the difficulty in attentional control associated with reduced cardiac vagal tone may extend to a broader social and moral context.
Background Impairments in facial emotion recognition have been a hallmark of autism, which may co... more Background Impairments in facial emotion recognition have been a hallmark of autism, which may contribute to the difficulty in social engagement and interpersonal interaction. Impaired facial emotion recognition in autism could be partly due to the asymmetrical perceptual bias to High Spatial Frequencies (HSF) information observed during visual perception. While Low Spatial Frequencies (LSF) convey coarse information, which would be critical for a fast analysis and categorization of emotional faces, HSF convey local information, which may serve a critical role in visual consciousness. However, to our knowledge, the effect of HSF on visual consciousness in autism has not been specifically studied so far. Methods Thirty-three adult autistic participants and 35 typically developing (TD) control participants performed an emotional attentional blink paradigm. Participants had to identify and report two targets (happy faces, T1 and T2) embedded in a stream of distractors (angry faces). Th...
The current research examines whether trait anxiety is associated with negative interpretation bi... more The current research examines whether trait anxiety is associated with negative interpretation bias when resolving valence ambiguity of surprised faces. To further isolate the neuro-cognitive mechanism, we presented angry, happy, and surprised faces at broad spatial frequency (BSF), high spatial frequency (HSF), and low spatial frequency (LSF) and asked participants to determine the valence of each face. High trait anxiety was associated with more negative interpretations of BSF (i.e., intact) surprised faces. However, the modulation of trait anxiety on the negative interpretation of surprised faces disappeared at HSF and LSF. The current study provides evidence that trait anxiety modulates negative interpretations of BSF surprised faces. However, the negative interpretation of LSF surprised faces appears to be a robust default response that occurs regardless of individual differences in trait anxiety.
Deficits in facial emotion processing is a major characteristic of patients with panic disorder. ... more Deficits in facial emotion processing is a major characteristic of patients with panic disorder. It is known that visual stimuli with different spatial frequencies take distinct neural pathways. This study investigated facial emotion processing involving stimuli presented at broad, high, and low spatial frequencies in patients with panic disorder. Eighteen patients with panic disorder and 19 healthy controls were recruited. Seven event-related potential (ERP) components: (P100, N170, early posterior negativity (EPN); vertex positive potential (VPP), N250, P300; and late positive potential (LPP)) were evaluated while the participants looked at fearful and neutral facial stimuli presented at three spatial frequencies. When a fearful face was presented, panic disorder patients showed a significantly increased P100 amplitude in response to low spatial frequency compared to high spatial frequency; whereas healthy controls demonstrated significant broad spatial frequency dependent process...
Patients with schizophrenia present with dysfunction of the magnocellular pathway, which might im... more Patients with schizophrenia present with dysfunction of the magnocellular pathway, which might impair their early visual processing. We explored the relationship between functional abnormality of early visual processing and brain volumetric changes in schizophrenia. Eighteen patients and 16 healthy controls underwent electroencephalographic recordings and high-resolution magnetic resonance imaging. During electroencephalographic recordings, participants passively viewed neutral or fearful faces with broad, high, or low spatial frequency characteristics. Voxel-based morphometry was performed to investigate brain volume correlates of visual processing deficits. Event related potential analysis suggested that patients with schizophrenia had relatively impaired P100 processing of low spatial frequency fearful face stimuli compared with healthy controls; patients' gray-matter volumes in the dorsolateral and medial prefrontal cortices positively correlated with this amplitude. In addi...
Human faces automatically attract visual attention and this process appears to be guided by socia... more Human faces automatically attract visual attention and this process appears to be guided by social group memberships. In two experiments, we examined how social groups guide selective attention toward in-group and out-group faces. Black and White participants detected a target letter among letter strings superimposed on faces (Experiment 1). White participants were less accurate on trials with racial out-group (Black) compared to in-group (White) distractor faces. Likewise, Black participants were less accurate on trials with racial out-group (White) compared to in-group (Black) distractor faces. However, this pattern of out-group bias was only evident under high perceptual load-when the task was visually difficult. To examine the malleability of this pattern of racial bias, a separate sample of participants were assigned to mixed-race minimal groups (Experiment 2). Participants assigned to groups were less accurate on trials with their minimal in-group members compared to minimal out-group distractor faces, regardless of race. Again, this pattern of out-group bias was only evident under high perceptual load. Taken together, these results suggest that social identity guides selective attention toward motivationally relevant social groups-shifting from out-group bias in the domain of race to in-group bias in the domain of minimal groups-when perceptual resources are scarce.
From the heart to the mind's eye: Cardiac vagal tone is related to visual perception of fear... more From the heart to the mind's eye: Cardiac vagal tone is related to visual perception of fearful faces at high spatial frequency Gewn hi Park
Another gene associated with anxiety disorders is the Catechol-O-methyltransferase (COMT) genetic... more Another gene associated with anxiety disorders is the Catechol-O-methyltransferase (COMT) genetic variation (Funke et al., 2005). COMT is an enzyme that plays an important role in the metabolism of brain dopamine and norepinephrine (Gadow et al., 2009). The COMT gene can be found in chromosome 22q11 and contains several single nucleotide polymorphisms (SNPs) that are functionally important. For example, Val158Met (rs4680)-associated with encoding either valine (Val) or methionine (Met)-plays an important role in modulating COMT activity in the prefrontal cortex (Harrison et al., 2008). Current evidences suggest that Val158Met may be associated with anxiety disorders, particularly bipolar disorder, via controlling dopamine activity in the prefrontal cortex (Funke et al.,2005). Individuals with Val158 homozygous showed 35-50% higher COMT activity in human dorsolateral prefrontal cortex than those with Mel158 homozygous (Harrison et al., 2008). Although Met-COMT is considered to play an important role in the development of bipolar disorder, there exists evidence that Val-COMT is also associated with bipolar disorder (Funke et al., 2005). Lastly, the brain-derived neurotrophic factor (BDNF) gene variants are suggested to be linked with anxiety disorders (Chen et al., 2006; Gadow et al., 2009). BDNF is a neurotrophin that plays an important role in neuronal growth, differentiation, and synaptic plasticity (Chen et al., 2006; Gadow et al., 2009; Rasmusson et al., 2002). BDNF is also associated with learning and memory and modulates aggression (Rasmusson et al., 2002). It has been reported that BDNF plays a role in mediating effects of stress (Rasmusson et al., 2002). Reduced BDNF expression in the hippocampus was observed in response to stress, which may contribute to hippocampus-dependent memory deficits and the decreases in hippocampal volume associated with patients with post-traumatic stress disorder (PTSD; Rasmusson et al., 2002). Recent studies investigated the relationship between a SNP in the BDNF gene, Val66Met, and psychopathology, which yielded conflicting results (Jiang et al., 2005). In an animal study, when exposed to stress, BDNF Met/Met mice demonstrated anxiety-related behaviors and were not responsive to the antidepressant, fluoxetine (Chen et al., 2006). Studies showed that Val66 allele were associated with greater neuroticisim scores, suggesting that individuals with the Val allele may have increased risk for developing anxiety or depression (Hünnerkopf et al., 2007; Sen et al., 2003). However, no association between BDNF Val66Met genotypes and neuroticisim was observed in Asian female participants (Tsai et al., 2004). BDNF Met66 allele was found to be a risk allele for anxiety and depression (Jiang et al., 2005) whereas other found it to be a protective allele for obsessive-compulsive disorder (OCD; Hall et al., 2003). In sum, BDNF may be related to anxiety disorder though it is yet to be determined which specific variant is responsible for the pathogenesis of anxiety disorders (Gadow et al., 2009). So far, we have presented different candidate genetic marker of anxiety disorders. To have better understanding of anxiety disorders, it would be important to identify genetic polymorphisms associated with anxiety disorders and study together with psychophysiological markers which will be discussed later.
We examined whether cardiac vagal tone (indexed by heart rate variability: HRV) was associated wi... more We examined whether cardiac vagal tone (indexed by heart rate variability: HRV) was associated with the functioning of selective attention under load. Participants were instructed to detect a target letter among letter strings superimposed on either fearful or neutral distractor faces. Under low load, when letter strings consisted of six target letters, there was no difference between people with high and low HRV on task performance. Under high load, when letter strings consisted of one target letter and five non-target letters, people with high HRV were faster in trials with neutral distractors, but not with fearful distractors. However, people with low HRV were slower in trials with both fearful and neutral distractors. The current research suggests cardiac vagal tone is associated with successful control of selective attention critical for goaldirected behavior and its impact is greater when fewer cognitive resources are available.
We investigated gender differences in event-related potential (ERP) responses to subliminally pre... more We investigated gender differences in event-related potential (ERP) responses to subliminally presented threat-related stimuli. Twenty-four participants were presented with threat-related and neutral pictures for a very brief period of time (17 ms). To explore gender differences in ERP responses to subliminally presented stimuli, we examined six ERP components [P1, N170, N250, P300, Early Posterior Negativity (EPN) and Late Positive Potential (LPP)]. The result revealed that only female participants showed significant increases in the N170 and the EPN in response to subliminally presented threat-related stimuli compared to neutral stimuli. Our results suggest that female participants exhibit greater cortical processing of subliminally presented threat-related stimuli than male participants.
ketamine group when compared to saline (p=0.01 and p<0.01 respectively). While the two treatment ... more ketamine group when compared to saline (p=0.01 and p<0.01 respectively). While the two treatment groups did not differ in their reaction times to the task, accuracy in the ketamine group worsened significantly more with increase in task difficulty than in controls (F(1,42)=1.833, p =0.05). Ketamine also significantly increased the P1 amplitude in response to both encoding and retrieval stimuli (F(2,84)=4.66, p<0.05 and F(2,84)=4.2, p=0.05 respectively). CADSS but not BPRS was correlated with P1 amplitude at trend (R=0.27, p=0.08 and R=0.26, p=0.09 for encoding and retrieval respectively). There was also a decrease in P300 for encoding (F(2,84)=4.53, p<0.05) and retrieval (F(2,84)=3.00 p=0.09). The encoding P300 but not P1 amplitude correlated with percentage correct responses. Drug pretreatment did not affect power or PLF in the theta frequency band but they were correlated with the CADSS scores (R=0.37, p=0.1 and R=0.38, p=0.07, respectively). Discussion: In this study acute NMDA antagonism induced a WM deficit that was associated with visual processing abnormalities. Specifically, ketamine increased the amplitude of the P1 potential and the signal power and PLF of low frequency evoked oscillations which is contrary to the pattern observed in schizophrenia spectrum disorders. These effects could be mediated ketamine-induced acute glutamate release in the visual cortex, enhancing neuronal responses to visual stimuli. P300 amplitude was reduced in the ketamine group and this correlated with impaired WM performance accuracy. We speculate that impaired NMDA function accounts for the reduced P300 following ketamine and that this mimics the same abnormalities in schizophrenia.
We examined the relationship between tonic-a correlate of self-regulatory functioning-and phasic ... more We examined the relationship between tonic-a correlate of self-regulatory functioning-and phasic cardiac vagal activity (indexed by heart rate variability; HRV) during a selective attentional task with varying levels of load. Participants detected a target letter among letter strings superimposed on either fearful or neutral face distractors. Letter strings consisted of six target letters under low load and one target letter and five nontarget letters under high load. With fearful distractors, lower tonic HRV was associated with phasic HRV suppression, suggesting an autonomic stress response under both low and high load. In contrast, higher tonic HRV was associated with phasic HRV enhancement, suggesting greater self-regulatory effort under low load and an absence of phasic HRV suppression under high load. The current research suggests that tonic cardiac vagal tone is associated with the ability to flexibly adapt autonomic responses.
The current research examines individual differences in flexible emotional attention. In two expe... more The current research examines individual differences in flexible emotional attention. In two experiments, we investigated the relationship between individual differences in cardiac vagal tone and top-down and bottom-up processes associated with emotional attention. To help determine the role of cortical and subcortical mechanisms underlying top-down and bottom-up emotional attention, fearful faces at broad, high, and low spatial frequency were presented as cues that triggered either exogenous or endogenous orienting. Participants with lower heart rate variability (HRV) exhibited faster attentional engagement to low-spatial-frequency fearful faces at short stimulus-onset asynchronies, but showed delayed attentional disengagement from high-spatial-frequency fearful faces at long stimulus-onset asynchronies in contrast to participants with higher HRV. This research suggests that cardiac vagal tone is associated with more adaptive top-down and bottom-up modulation of emotional attention. Implications for various affective disorders, including depression, anxiety disorders, and posttraumatic stress disorder, are discussed.
proposes that individual differences in heart rate variability (HRV)-an index of cardiac vagal to... more proposes that individual differences in heart rate variability (HRV)-an index of cardiac vagal tone-are associated with attentional and emotional self-regulation. In this article, we demonstrate that individual differences in resting HRV predict the functioning of the inhibition of return (IOR), an inhibitory attentional mechanism highly adaptive to novelty search, in response to affectively significant face cues. As predicted, participants with lower HRV exhibited a smaller IOR effect to fearful versus neutral face cues than participants with higher HRV, which shows a failure to inhibit attention from affectively significant cues and instigate novelty search. In contrast, participants with higher HRV exhibited similar IOR effects to fearful and neutral face cues, which shows an ability to inhibit attention from cues and instigate novelty search. Their ability to inhibit attention was most pronounced to high spatial frequency fearful face cues, suggesting that this effect may be mediated by cortical mechanisms. The current research demonstrates that individual differences in HRV predict attentional inhibition and suggests that successful inhibition and novelty search may be mediated by cortical inhibitory mechanisms among people with high cardiac vagal tone.
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