Publications by authors named "Steven G Greening"

25 Publications

  • Page 1 of 1

Emotion regulation in emerging adults with major depressive disorder and frequent cannabis use.

Neuroimage Clin 2021 Jan 26;30:102575. Epub 2021 Jan 26.

Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada; Imaging Division, Lawson Health Research Institute, London, Canada; First Episode Mood and Anxiety Program (FEMAP), London Health Sciences Centre, London, Canada; Department of Medical Biophysics, University of Western Ontario, London, Canada. Electronic address:

In people with mental health issues, approximately 20% have co-occurring substance use, often involving cannabis. Although emotion regulation can be affected both by major depressive disorder (MDD) and by cannabis use, the relationship among all three factors is unknown. In this study, we used fMRI to evaluate the effect that cannabis use and MDD have on brain activation during an emotion regulation task. Differences were assessed in 74 emerging adults aged 16-23 with and without MDD who either used or did not use cannabis. Severity of depressive symptoms, emotion regulation style, and age of cannabis use onset were also measured. Both MDD and cannabis use interacted with the emotion regulation task in the left temporal lobe, however the location of the interaction differed for each factor. Specifically, MDD showed an interaction with emotion regulation in the middle temporal gyrus, whereas cannabis use showed an interaction in the superior temporal gyrus. Emotion regulation style predicted activity in the right superior frontal gyrus, however, this did not interact with MDD or cannabis use. Severity of depressive symptoms interacted with the emotion regulation task in the left middle temporal gyrus. The results highlight the influence of cannabis use and MDD on emotion regulation processing, suggesting that both may have a broader impact on the brain than previously thought.
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http://dx.doi.org/10.1016/j.nicl.2021.102575DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7895841PMC
January 2021

Cortical thickness and resting-state cardiac function across the lifespan: A cross-sectional pooled mega-analysis.

Psychophysiology 2020 Oct 10. Epub 2020 Oct 10.

Norwegian Centre for Mental Disorders Research (NORMENT), Institute of Clinical Medicine, University of Oslo, Oslo, Norway.

Understanding the association between autonomic nervous system [ANS] function and brain morphology across the lifespan provides important insights into neurovisceral mechanisms underlying health and disease. Resting-state ANS activity, indexed by measures of heart rate [HR] and its variability [HRV] has been associated with brain morphology, particularly cortical thickness [CT]. While findings have been mixed regarding the anatomical distribution and direction of the associations, these inconsistencies may be due to sex and age differences in HR/HRV and CT. Previous studies have been limited by small sample sizes, which impede the assessment of sex differences and aging effects on the association between ANS function and CT. To overcome these limitations, 20 groups worldwide contributed data collected under similar protocols of CT assessment and HR/HRV recording to be pooled in a mega-analysis (N = 1,218 (50.5% female), mean age 36.7 years (range: 12-87)). Findings suggest a decline in HRV as well as CT with increasing age. CT, particularly in the orbitofrontal cortex, explained additional variance in HRV, beyond the effects of aging. This pattern of results may suggest that the decline in HRV with increasing age is related to a decline in orbitofrontal CT. These effects were independent of sex and specific to HRV; with no significant association between CT and HR. Greater CT across the adult lifespan may be vital for the maintenance of healthy cardiac regulation via the ANS-or greater cardiac vagal activity as indirectly reflected in HRV may slow brain atrophy. Findings reveal an important association between CT and cardiac parasympathetic activity with implications for healthy aging and longevity that should be studied further in longitudinal research.
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http://dx.doi.org/10.1111/psyp.13688DOI Listing
October 2020

Strengthening spatial reasoning: elucidating the attentional and neural mechanisms associated with mental rotation skill development.

Cogn Res Princ Implic 2020 05 5;5(1):20. Epub 2020 May 5.

Department of Psychology, Louisiana State University, 236 Audubon Hall, Baton Rouge, LA, 70803, USA.

Spatial reasoning is a critical skill in many everyday tasks and in science, technology, engineering, and mathematics disciplines. The current study examined how training on mental rotation (a spatial reasoning task) impacts the completeness of an encoded representation and the ability to rotate the representation. We used a multisession, multimethod design with an active control group to determine how mental rotation ability impacts performance for a trained stimulus category and an untrained stimulus category. Participants in the experimental group (n = 18) showed greater improvement than the active control group (n = 18) on the mental rotation tasks. The number of saccades between objects decreased and saccade amplitude increased after training, suggesting that participants in the experimental group encoded more of the object and possibly had more complete mental representations after training. Functional magnetic resonance imaging data revealed distinct neural activation associated with mental rotation, notably in the right motor cortex and right lateral occipital cortex. These brain areas are often associated with rotation and encoding complete representations, respectively. Furthermore, logistic regression revealed that activation in these brain regions during the post-training scan significantly predicted training group assignment. Overall, the current study suggests that effective mental rotation training protocols should aim to improve the encoding and manipulation of mental representations.
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http://dx.doi.org/10.1186/s41235-020-00211-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7200965PMC
May 2020

Relationships between multiple dimensions of executive functioning and resting-state networks in adults.

Neuropsychologia 2020 04 10;141:107418. Epub 2020 Mar 10.

Department of Psychology, Louisiana State University, Baton Rouge, LA, United States.

The current study sought to examine the functional connectivity of resting state networks (RSNs) as they relate to the individual domains of executive functioning (EF). Based on the Unity and Diversity model (Miyake et al., 2000), EF performance was captured using a three-factor model proposed by Karr et al. (2018), which includes inhibition, shifting, and fluency. Publicly available data was used from the Nathan Kline Institute -Rockland project was used. Of the 722 participants who completed the Delis-Kaplan Executive Function System (D-KEFS), which was used to measure EF performance, 269 of these individuals completed resting state fMRI scans. First, a confirmatory factory analysis replicated Karr et al. (2018) revealing three components: inhibition, shifting and fluency. Next, RSNs were identified across the sample using an Independent Components Analysis (ICA) and was compared to previously established intrinsic connectivity networks (Laird et al., 2011). Finally, dual regression was used to analyze the relationships between the functional connectivity of RSNs and EF performance, which indicated that RSNs were differentially associated with inhibition and shifting. Better inhibition was related to increased connectivity between the left striatum and the attentional control network. Better shifting performance was related to increased connectivity between the pre- and postcentral gyri and the speech and sensorimotor network. These results highlight individual differences within these RSNs that are unique to the literature, as non-EF confounds are mitigated within the current measurements of EF performance.
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http://dx.doi.org/10.1016/j.neuropsychologia.2020.107418DOI Listing
April 2020

Basic Processes in Dynamic Decision Making: How Experimental Findings About Risk, Uncertainty, and Emotion Can Contribute to Police Decision Making.

Front Psychol 2019 20;10:2140. Epub 2019 Sep 20.

Department of Psychology, Louisiana State University, Baton Rouge, LA, United States.

In this paper, we review basic findings from experimental studies in judgment and decision making that could contribute to designing policies and trainings to enhance police decision making. Traditional judgment and decision-making research has focused on simple choices between hypothetical gambles, which has been criticized for its lack of generalizability to real world contexts. Over the past 15 years, researchers have focused on understanding the dynamic processes in decision making. This recent focus has allowed for the possibility of more generalizable applications of basic decision science to social issues. We review recent work in three dynamic decision-making topics: dynamic accumulation of evidence in the decision to shoot or not shoot, how previous decisions influence current choices, and how the cognitive and neurological processing of fear influences decisions and decision errors. We conclude this review with a summary of how basic experimental research can apply in policing and training.
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http://dx.doi.org/10.3389/fpsyg.2019.02140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6763579PMC
September 2019

The effects of childhood inattention and anxiety on executive functioning: inhibition, updating, and shifting.

Atten Defic Hyperact Disord 2019 Dec 14;11(4):423-432. Epub 2019 May 14.

Department of Psychology, Louisiana State University, 236 Audubon Hall, Baton Rouge, LA, 70803, USA.

Although anxiety and attention-deficit/hyperactivity disorder (ADHD) symptoms are highly comorbid, research has generally examined the executive functioning (EF) deficits associated with each of these symptoms independently. The purpose of this study was to examine the unique and interactive effects of anxiety and ADHD symptoms (first respectively, then collectively) on multiple dimensions of EF (i.e., inhibition, updating, and shifting, respectively). A sample of 142 youth from the community (age range 8-17 years; M = 11.87 ± 2.94 years) completed the Delis-Kaplan Executive Function System and dimensional measures of anxiety, inattention, and hyperactivity/impulsivity. It was hypothesized that anxiety would moderate the effect of ADHD symptomatology on EF. Multiple regression models examined anxiety and ADHD symptom domains as predictors of EF. When examining ADHD symptom domains separately, anxiety moderated the relationship between inattention and both updating and shifting; the association between hyperactivity/impulsivity and updating was also moderated by anxiety. Within the full model including both ADHD symptom domains, results indicated that anxiety moderated the relationship between inattention and shifting. Analyses of ADHD symptoms in separate and combined models demonstrated a similar pattern: Increased inattention was associated with worse EF and when anxiety was a significant moderator, and increased ADHD symptoms were associated with worse EF only for those with high levels of anxiety. These results highlight the utility of including anxiety in studies examining the relationship between ADHD and EF. EF is related to multiple aspects of daily functioning (e.g., academic achievement), and EF deficits are often targeted in interventions for ADHD.
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http://dx.doi.org/10.1007/s12402-019-00306-7DOI Listing
December 2019

Fear of the known: semantic generalisation of fear conditioning across languages in bilinguals.

Cogn Emot 2020 03 15;34(2):352-358. Epub 2019 Apr 15.

CNAPs Lab, Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.

While modern theories of emotion emphasize the role of higher-order cognitive processes such as semantics in human emotion, much research into emotional learning has ignored the potential contributions of such processes. This study aimed to determine whether emotional learning affects semantic representations of words independent of perceptual features by assessing whether fear conditioning to a neutral word generalises across languages in bilingual participants. Two sessions differing according to the reinforced language were performed by English-Spanish bilinguals. In each session, a neutral word was reinforced by an electrical shock whereas its equivalent in the other language was never paired with shock. Across two sessions within our sample, we found replicable evidence that fear conditioning consistently transferred to the non-reinforced language as measured by both self-reported fear and electrodermal activity, irrespective of the conditioned language. Our findings extend knowledge about the role of semantic similarity in fear generalisation and highlight the importance of higher-order cognitive processes in human emotions.
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http://dx.doi.org/10.1080/02699931.2019.1604319DOI Listing
March 2020

Opening the reconsolidation window using the mind's eye: Extinction training during reconsolidation disrupts fear memory expression following mental imagery reactivation.

Cognition 2019 02 7;183:277-281. Epub 2018 Dec 7.

CNAPs Lab, Department of Psychology, Louisiana State University, B3 Audubon Hall, Baton Rouge, LA 70803, United States. Electronic address:

Can mental imagery rather than external stimulation reactivate an aversive conditioned memory for the purposes of attenuating fear with subsequent extinction training? To answer this question participant underwent a three-day protocol: Day 1 entailed fear acquisition training in which two conditioned stimuli were paired with mild shock (US), while a CS- never was; day 2 included imagery-based reactivation of only one of the two CS+ followed by standard extinction training within the reconsolidation ten minutes later; day 3 included reinstatement by the unsignaled presentation of the US followed by a re-extinction phase. We observed no evidence of fear recovery on the first trial of re-extinction for the reminded, mentally imaged, CS+, whereas fear returned for the non-reminded CS+. Thus, mental imagery was sufficient to reactivate a fear memory thereby opening the reconsolidation window and facilitating fear suppression via extinction training. The clinical implications of this are potentially far-reaching as it allows for in vivo reconsolidation procedures in exposure therapy.
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http://dx.doi.org/10.1016/j.cognition.2018.12.001DOI Listing
February 2019

Arousal increases neural gain via the locus coeruleus-norepinephrine system in younger adults but not in older adults.

Nat Hum Behav 2018 7;2:356-366. Epub 2018 May 7.

Department of Psychology, University of Southern California, Los Angeles, CA, USA.

In younger adults, arousal amplifies attentional focus to the most salient or goal-relevant information while suppressing other information. A computational model of how the locus coeruleus-norepinephrine (LC-NE) system can implement this increased selectivity under arousal and an fMRI study comparing how arousal affects younger and older adults' processing indicate that the amplification of salient stimuli and the suppression of non-salient stimuli are separate processes, with aging affecting suppression without impacting amplification under arousal. In the fMRI study, arousal increased processing of salient stimuli and decreased processing of non-salient stimuli for younger adults. In contrast, for older adults, arousal increased processing of both low and high salience stimuli, generally increasing excitatory responses to visual stimuli. Older adults also showed decline in LC functional connectivity with frontoparietal networks that coordinate attentional selectivity. Thus, among older adults, arousal increases the potential for distraction from non-salient stimuli.
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http://dx.doi.org/10.1038/s41562-018-0344-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6176734PMC
May 2018

Spatially generalizable representations of facial expressions: Decoding across partial face samples.

Cortex 2018 04 6;101:31-43. Epub 2017 Dec 6.

School of Psychology, University of East Anglia, Norwich, UK. Electronic address:

A network of cortical and sub-cortical regions is known to be important in the processing of facial expression. However, to date no study has investigated whether representations of facial expressions present in this network permit generalization across independent samples of face information (e.g., eye region vs mouth region). We presented participants with partial face samples of five expression categories in a rapid event-related fMRI experiment. We reveal a network of face-sensitive regions that contain information about facial expression categories regardless of which part of the face is presented. We further reveal that the neural information present in a subset of these regions: dorsal prefrontal cortex (dPFC), superior temporal sulcus (STS), lateral occipital and ventral temporal cortex, and even early visual cortex, enables reliable generalization across independent visual inputs (faces depicting the 'eyes only' vs 'eyes removed'). Furthermore, classification performance was correlated to behavioral performance in STS and dPFC. Our results demonstrate that both higher (e.g., STS, dPFC) and lower level cortical regions contain information useful for facial expression decoding that go beyond the visual information presented, and implicate a key role for contextual mechanisms such as cortical feedback in facial expression perception under challenging conditions of visual occlusion.
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http://dx.doi.org/10.1016/j.cortex.2017.11.016DOI Listing
April 2018

Parsing the neural correlates of anxious apprehension and anxious arousal in the grey-matter of healthy youth.

Brain Imaging Behav 2018 Aug;12(4):1084-1098

Department of Psychology, Louisiana State University, 236 Audubon Hall, Baton Rouge, LA, 70803, USA.

Neuroscientific and psychological research posits that there are two transdiagnostic facets of anxiety: anxious arousal and anxious apprehension. Though these two facets of anxiety are distinct, they are often subsumed into one domain (e.g., trait anxiety). The primary goal of the current study was to delineate the relationship between anxious arousal and cortical thickness versus the relationship between anxious apprehension and cortical thickness in a sample of typically functioning youth. The secondary aim was to determine where in the brain cortical thickness significantly correlated with both components of anxiety. Results indicated that the right anterior insula has a stronger relationship to anxious arousal, whereas the dorsolateral prefrontal cortex and left anterior insula were found to correlate with both anxious arousal and apprehension. We also observed volumetric differences in the amygdala and hippocampus between anxious arousal and anxious apprehension. Whereas anxious arousal, but not apprehension, predicted left amygdala volume, anxious apprehension, but not arousal, predicted right hippocampal volume. These findings demonstrated that there are both differences and similarities in the neural regions that contribute to independent facets of anxiety. Results are discussed in terms of previous findings from the affective and developmental cognitive neurosciences.
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http://dx.doi.org/10.1007/s11682-017-9772-1DOI Listing
August 2018

Higher locus coeruleus MRI contrast is associated with lower parasympathetic influence over heart rate variability.

Neuroimage 2017 04 17;150:329-335. Epub 2017 Feb 17.

Department of Psychology, The Ohio State University, Columbus, OH, USA.

The locus coeruleus (LC) is a key node of the sympathetic nervous system and suppresses parasympathetic activity that would otherwise increase heart rate variability. In the current study, we examined whether LC-MRI contrast reflecting neuromelanin accumulation in the LC was associated with high-frequency heart rate variability (HF-HRV), a measure reflecting parasympathetic influences on the heart. Recent evidence indicates that neuromelanin, a byproduct of catecholamine metabolism, accumulates in the LC through young and mid adulthood, suggesting that LC-MRI contrast may be a useful biomarker of individual differences in habitual LC activation. We found that, across younger and older adults, greater LC-MRI contrast was negatively associated with HF-HRV during fear conditioning and spatial detection tasks. This correlation was not accounted for by individual differences in age or anxiety. These findings indicate that individual differences in LC structure relate to key cardiovascular parameters.
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http://dx.doi.org/10.1016/j.neuroimage.2017.02.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5391255PMC
April 2017

How arousal influences neural competition: What dual competition does not explain.

Behav Brain Sci 2015 ;38:e77

Davis School of Gerontology,University of Southern California,Los Angeles,CA

We argue that although the "dual competition" model is useful when considering interactions between emotional and neutral stimuli, it fails to account for the influence of emotional arousal on perceptual or goal-directed behavior involving neutral stimuli. We present the "arousal-biased competition" framework as an alternative that accounts for both scenarios.
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http://dx.doi.org/10.1017/S0140525X14000910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5793857PMC
August 2016

A network of amygdala connections predict individual differences in trait anxiety.

Hum Brain Mapp 2015 Dec 10;36(12):4819-30. Epub 2015 Sep 10.

Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.

In this study we demonstrate that the pattern of an amygdala-centric network contributes to individual differences in trait anxiety. Individual differences in trait anxiety were predicted using maximum likelihood estimates of amygdala structural connectivity to multiple brain targets derived from diffusion-tensor imaging (DTI) and probabilistic tractography on 72 participants. The prediction was performed using a stratified sixfold cross validation procedure using a regularized least square regression model. The analysis revealed a reliable network of regions predicting individual differences in trait anxiety. Higher trait anxiety was associated with stronger connections between the amygdala and dorsal anterior cingulate cortex, an area implicated in the generation of emotional reactions, and inferior temporal gyrus and paracentral lobule, areas associated with perceptual and sensory processing. In contrast, higher trait anxiety was associated with weaker connections between amygdala and regions implicated in extinction learning such as medial orbitofrontal cortex, and memory encoding and environmental context recognition, including posterior cingulate cortex and parahippocampal gyrus. Thus, trait anxiety is not only associated with reduced amygdala connectivity with prefrontal areas associated with emotion modulation, but also enhanced connectivity with sensory areas. This work provides novel anatomical insight into potential mechanisms behind information processing biases observed in disorders of emotion.
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http://dx.doi.org/10.1002/hbm.22952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6869108PMC
December 2015

Individual Differences in Anticipatory Somatosensory Cortex Activity for Shock is Positively Related with Trait Anxiety and Multisensory Integration.

Brain Sci 2016 Jan 6;6(1). Epub 2016 Jan 6.

Department of Psychology, University of Southern California, Los Angeles, CA 90089, USA.

Anxiety is associated with an exaggerated expectancy of harm, including overestimation of how likely a conditioned stimulus (CS+) predicts a harmful unconditioned stimulus (US). In the current study we tested whether anxiety-associated expectancy of harm increases primary sensory cortex (S1) activity on non-reinforced (i.e., no shock) CS+ trials. Twenty healthy volunteers completed a differential-tone trace conditioning task while undergoing fMRI, with shock delivered to the left hand. We found a positive correlation between trait anxiety and activity in right, but not left, S1 during CS+ versus CS- conditions. Right S1 activity also correlated with individual differences in both primary auditory cortices (A1) and amygdala activity. Lastly, a seed-based functional connectivity analysis demonstrated that trial-wise S1 activity was positively correlated with regions of dorsolateral prefrontal cortex (dlPFC), suggesting that higher-order cognitive processes contribute to the anticipatory sensory reactivity. Our findings indicate that individual differences in trait anxiety relate to anticipatory reactivity for the US during associative learning. This anticipatory reactivity is also integrated along with emotion-related sensory signals into a brain network implicated in fear-conditioned responding.
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http://dx.doi.org/10.3390/brainsci6010002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4810172PMC
January 2016

Encoding of goal-relevant stimuli is strengthened by emotional arousal in memory.

Front Psychol 2015 10;6:1173. Epub 2015 Aug 10.

Department of Psychology, University of Southern California , Los Angeles, CA, USA ; Davis School of Gerontology, University of Southern California , Los Angeles, CA, USA ; Neuroscience Graduate Programs, University of Southern California , Los Angeles, CA, USA.

Emotional information receives preferential processing, which facilitates adaptive strategies for survival. However, the presence of emotional stimuli and the arousal they induce also influence how surrounding non-emotional information is processed in memory (Mather and Sutherland, 2011). For example, seeing a highly emotional scene often leads to forgetting of what was seen right beforehand, but sometimes instead enhances memory for the preceding information. In two studies, we examined how emotional arousal affects short-term memory retention for goal-relevant information that was just seen. In Study 1, participants were asked to remember neutral objects in spatially-cued locations (i.e., goal-relevant objects determined by specific location), while ignoring objects in uncued locations. After each set of objects were shown, arousal was manipulated by playing a previously fear-conditioned tone (i.e., CS+) or a neutral tone that had not been paired with shock (CS-). In Study 1, memory for the goal-relevant neutral objects from arousing trials was enhanced compared to those from the non-arousing trials. This result suggests that emotional arousal helps to increase the impact of top-down priority (i.e., goal-relevancy) on memory encoding. Study 2 supports this conclusion by demonstrating that when the goal was to remember all objects regardless of the spatial cue, emotional arousal induced memory enhancement in a more global manner for all objects. In sum, the two studies show that the ability of arousal to enhance memory for previously encoded items depends on the goal relevance initially assigned to those items.
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http://dx.doi.org/10.3389/fpsyg.2015.01173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4530598PMC
August 2015

Multivariate cross-classification: applying machine learning techniques to characterize abstraction in neural representations.

Front Hum Neurosci 2015 25;9:151. Epub 2015 Mar 25.

Department of Psychology, University of Southern California Los Angeles, CA, USA ; Department of Gerontology, University of Southern California Los Angeles, CA, USA.

Here we highlight an emerging trend in the use of machine learning classifiers to test for abstraction across patterns of neural activity. When a classifier algorithm is trained on data from one cognitive context, and tested on data from another, conclusions can be drawn about the role of a given brain region in representing information that abstracts across those cognitive contexts. We call this kind of analysis Multivariate Cross-Classification (MVCC), and review several domains where it has recently made an impact. MVCC has been important in establishing correspondences among neural patterns across cognitive domains, including motor-perception matching and cross-sensory matching. It has been used to test for similarity between neural patterns evoked by perception and those generated from memory. Other work has used MVCC to investigate the similarity of representations for semantic categories across different kinds of stimulus presentation, and in the presence of different cognitive demands. We use these examples to demonstrate the power of MVCC as a tool for investigating neural abstraction and discuss some important methodological issues related to its application.
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http://dx.doi.org/10.3389/fnhum.2015.00151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4373279PMC
April 2015

A dual process for the cognitive control of emotional significance: implications for emotion regulation and disorders of emotion.

Front Hum Neurosci 2014 25;8:253. Epub 2014 Apr 25.

Davis School of Gerontology, University of Southern California Los Angeles, CA, USA ; Department of Psychology, University of Southern California Los Angeles, CA, USA ; Neuroscience Graduate Program, University of Southern California Los Angeles, CA, USA.

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http://dx.doi.org/10.3389/fnhum.2014.00253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4007012PMC
May 2014

Emotion-related brain activity to conflicting socio-emotional cues in unmedicated depression.

J Affect Disord 2013 Sep 14;150(3):1136-41. Epub 2013 Jun 14.

Department of Anatomy & Cell Biology, Schulich School of Medicine & Dentistry, London, Ontario, Canada.

Background: Abnormalities in amygdala function have been implicated in major depression. However, results are inconsistent, and little is known about how the depressed brain encodes conflicting social signals. We sought to determine how the task relevance of socio-emotional cues impacts neural encoding of emotion in depression.

Methods: Eighteen medication-free depressed patients and 18 matched controls participated in an FMRI experiment. Whole-brain analyses and a region-of-interest approach was used to measure amygdala activity during the presentation of fearful, happy, or neutral target faces with congruent, incongruent, or neutral distracters.

Results: Greater amygdala activity to target fearful faces was associated with depression, as was attenuated amygdala activity to target and peripheral happy faces. Although no group differences emerged in the amygdala to unattended fearful faces, we observed reduced ventrolateral and dorsomedial prefrontal activity in depressed individuals during this condition.

Limitations: Nine patients had a history of anti-depressant use, though they were unmedicated for at least three months at testing.

Conclusions: Depression was associated with reduced amygdala reactivity to positive social stimuli. However, enhanced amygdala responsiveness to negative emotional cues was only observed to target (attended) expressions. The results highlight the need to further determine factors that affect emotional reactivity in depression.
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http://dx.doi.org/10.1016/j.jad.2013.05.053DOI Listing
September 2013

Emotion modulates activity in the 'what' but not 'where' auditory processing pathway.

Neuroimage 2013 Nov 24;82:295-305. Epub 2013 May 24.

Graduate Program in Neuroscience, University of Western Ontario, London, Ontario N6A 5A5, Canada.

Auditory cortices can be separated into dissociable processing pathways similar to those observed in the visual domain. Emotional stimuli elicit enhanced neural activation within sensory cortices when compared to neutral stimuli. This effect is particularly notable in the ventral visual stream. Little is known, however, about how emotion interacts with dorsal processing streams, and essentially nothing is known about the impact of emotion on auditory stimulus localization. In the current study, we used fMRI in concert with individualized auditory virtual environments to investigate the effect of emotion during an auditory stimulus localization task. Surprisingly, participants were significantly slower to localize emotional relative to neutral sounds. A separate localizer scan was performed to isolate neural regions sensitive to stimulus location independent of emotion. When applied to the main experimental task, a significant main effect of location, but not emotion, was found in this ROI. A whole-brain analysis of the data revealed that posterior-medial regions of auditory cortex were modulated by sound location; however, additional anterior-lateral areas of auditory cortex demonstrated enhanced neural activity to emotional compared to neutral stimuli. The latter region resembled areas described in dual pathway models of auditory processing as the 'what' processing stream, prompting a follow-up task to generate an identity-sensitive ROI (the 'what' pathway) independent of location and emotion. Within this region, significant main effects of location and emotion were identified, as well as a significant interaction. These results suggest that emotion modulates activity in the 'what,' but not the 'where,' auditory processing pathway.
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http://dx.doi.org/10.1016/j.neuroimage.2013.05.051DOI Listing
November 2013

The neural correlates of regulating positive and negative emotions in medication-free major depression.

Soc Cogn Affect Neurosci 2014 May 11;9(5):628-37. Epub 2013 Mar 11.

Brain and Mind Institute, Natural Sciences Building, University of Western Ontario, London, Ontario N6A 5B7, Canada.

Depressive cognitive schemas play an important role in the emergence and persistence of major depressive disorder (MDD). The current study adapted emotion regulation techniques to reflect elements of cognitive behavioural therapy (CBT) and related psychotherapies to delineate neurocognitive abnormalities associated with modulating the negative cognitive style in MDD. Nineteen non-medicated patients with MDD and 19 matched controls reduced negative or enhanced positive feelings elicited by emotional scenes while undergoing functional magnetic resonance imaging. Although both groups showed significant emotion regulation success as measured by subjective ratings of affect, the controls were significantly better at modulating both negative and positive emotion. Both groups recruited regions of dorsolateral prefrontal cortex and ventrolateral prefrontal cortex (VLPFC) when regulating negative emotions. Only in controls was this accompanied by reduced activity in sensory cortices and amygdala. Similarly, both groups showed enhanced activity in VLPFC and ventral striatum when enhancing positive affect; however, only in controls was ventral striatum activity correlated with regulation efficacy. The results suggest that depression is associated with both a reduced capacity to achieve relief from negative affect despite recruitment of ventral and dorsal prefrontal cortical regions implicated in emotion regulation, coupled with a disconnect between activity in reward-related regions and subjective positive affect.
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http://dx.doi.org/10.1093/scan/nst027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014100PMC
May 2014

Do fearful eyes activate empathy-related brain regions in individuals with callous traits?

Soc Cogn Affect Neurosci 2012 Nov 22;7(8):958-68. Epub 2011 Oct 22.

Program in Neuroscience, The University of Western Ontario, London, Ontario, Canada.

Psychopathy, a developmental disorder characterized by profound social disturbance, is associated with impaired recognition of distress cues. Since distress processing and moral socialization are closely linked, uncovering techniques to improve distress recognition could have positive treatment implications for developmental disorders that feature empathy impairments. Previous studies demonstrate that fear-recognition deficits can be remedied by redirecting attention to critical cues (the eyes for fearful faces). However, it remains unclear whether this manipulation increases activity in empathy-related brain regions, or has an alternate compensatory effect that may not promote prosocial behaviours. In this fMRI study, a community sample of individuals with high vs low callous traits completed an emotion recognition task that varied whether the most or least socially meaningful facial features were visible (the eyes were isolated or occluded). For fearful faces, individuals with high callous traits showed significantly less amygdala and medial prefrontal cortex activity than those with low callous traits when the eyes were occluded, but not when they were isolated. Consistent with recent models of the amygdala that emphasize orientation to disambiguate stimuli rather than represent distress, individuals with low trait empathy showed greater amygdala activity to the least vs most socially meaningful features of fearful faces.
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http://dx.doi.org/10.1093/scan/nsr068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501700PMC
November 2012

Conscious perception of emotional stimuli: brain mechanisms.

Neuroscientist 2012 Aug 9;18(4):386-98. Epub 2011 Sep 9.

Department of Psychiatry and Department of Anatomy & Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.

Emotional stimuli are thought to gain rapid and privileged access to processing resources in the brain. The structures involved in this enhanced access are thought to support subconscious, reflexive processes. Whether these pathways contribute to the phenomenological experience of emotional visual awareness (i.e., conscious perception) is unclear. In this review, it is argued that subcortical networks associated with the rapid detection of emotionally salient stimuli also play a key role in shaping awareness. This proposal is based on the idea that awareness of visual stimuli should be considered along a continuum, having intermediate levels, rather than as an all-or-none construct. It is also argued that awareness of emotional stimuli requires less input from frontoparietal structures that are often considered crucial for visual awareness. Evidence is also presented that implicates a region of the medial prefrontal cortex, involved in emotion regulation, in modulating amygdala output to determine awareness of emotional visual stimuli; when emotional stimuli are present, the conscious perception of alternative stimuli requires greater regulatory influences from cortical structures. Thus, emotional stimuli are privileged not only for neuronal representation and impact on subconscious processes, but also for awareness, allowing humans to deal flexibly rather than merely reflexively to biologically significant stimuli.
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http://dx.doi.org/10.1177/1073858411416515DOI Listing
August 2012

Parsing decision making processes in prefrontal cortex: response inhibition, overcoming learned avoidance, and reversal learning.

Neuroimage 2011 Jan 17;54(2):1432-41. Epub 2010 Sep 17.

Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada.

Reversal learning refers to the ability to inhibit or switch responding to an object when the object-reward contingency changes. Deficits in this process are related to social abnormalities, impulsiveness, and a number of psychiatric disorders. A range of neural regions play a role in this process, including dorsolateral prefrontal cortex (dlPFC), dorsomedial prefrontal cortex (dmPFC), and inferior frontal gyrus (IFG). However, determining the specific functional contribution of each region has proved difficult, in part because reversal learning involves multiple cognitive subprocesses such as error detection, inhibiting responding to formerly rewarded stimuli, and overcoming avoidance of previously punished stimuli. We used fMRI and an experimental task adapted from a recent neurochemical study in marmosets to parse neural responding to subprocesses of reversal learning during choice and feedback trial components. Error-feedback processing was associated with increased activity in dmPFC, dlPFC, and IFG whether participants were overcoming avoidance, inhibiting responding, or performing classic response reversal. Reduced activity in medial prefrontal cortex (mPFC) was associated with error-feedback processing for response inhibition but not overcoming avoidance. Conversely, there was significantly greater activity in anterior dmPFC during error-feedback processing in overcoming avoidance compared to response inhibition. A conjunction analysis confirmed that a striking overlap in activity was observed across the three conditions in IFG, dlPFC, and dmPFC. The results are consistent with conceptualizations of IFG function that emphasize modulating stimulus-response maps rather than purely response inhibition. The approach has implications for models of prefrontal function and neurocognitive perspectives on a range of behavioural abnormalities associated with impairments in decision making.
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http://dx.doi.org/10.1016/j.neuroimage.2010.09.017DOI Listing
January 2011

Multiple mechanisms of consciousness: the neural correlates of emotional awareness.

J Neurosci 2010 Jul;30(30):10039-47

Department of Psychiatry and Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, 339 Windermere Road, London, Ontario, Canada.

Emotional stimuli, including facial expressions, are thought to gain rapid and privileged access to processing resources in the brain. Despite this access, we are conscious of only a fraction of the myriad of emotion-related cues we face everyday. It remains unclear, therefore, what the relationship is between activity in neural regions associated with emotional representation and the phenomenological experience of emotional awareness. We used functional magnetic resonance imaging and binocular rivalry to delineate the neural correlates of awareness of conflicting emotional expressions in humans. Behaviorally, fearful faces were significantly more likely to be perceived than disgusted or neutral faces. Functionally, increased activity was observed in regions associated with facial expression processing, including the amygdala and fusiform gyrus during emotional awareness. In contrast, awareness of neutral faces and suppression of fearful faces were associated with increased activity in dorsolateral prefrontal and inferior parietal cortices. The amygdala showed increased functional connectivity with ventral visual system regions during fear awareness and increased connectivity with perigenual prefrontal cortex (pgPFC; Brodmann's area 32/10) when fear was suppressed. Despite being prioritized for awareness, emotional items were associated with reduced activity in areas considered critical for consciousness. Contributions to consciousness from bottom-up and top-down neural regions may be additive, such that increased activity in specialized regions within the extended ventral visual system may reduce demands on a frontoparietal system important for awareness. The possibility is raised that interactions between pgPFC and the amygdala, previously implicated in extinction, may also influence whether or not an emotional stimulus is accessible to consciousness.
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http://dx.doi.org/10.1523/JNEUROSCI.6434-09.2010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6633384PMC
July 2010