Publications by authors named "Neil Dundon"

13 Publications

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Ventromedial Prefrontal Cortex Activity and Sympathetic Allostasis During Value-Based Ambivalence.

Front Behav Neurosci 2021 22;15:615796. Epub 2021 Feb 22.

Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States.

Anxiety is characterized by low confidence in daily decisions, coupled with high levels of phenomenological stress. Ventromedial prefrontal cortex (vmPFC) plays an integral role in maladaptive anxious behaviors via decreased sensitivity to threatening vs. non-threatening stimuli (fear generalization). vmPFC is also a key node in approach-avoidance decision making requiring two-dimensional integration of rewards and costs. More recently, vmPFC has been implicated as a key cortical input to the sympathetic branch of the autonomic nervous system. However, little is known about the role of this brain region in mediating rapid stress responses elicited by changes in confidence during decision making. We used an approach-avoidance task to examine the relationship between sympathetically mediated cardiac stress responses, vmPFC activity and choice behavior over long and short time-scales. To do this, we collected concurrent fMRI, EKG and impedance cardiography recordings of sympathetic drive while participants made approach-avoidance decisions about monetary rewards paired with painful electric shock stimuli. We observe first that increased sympathetic drive (shorter pre-ejection period) in states lasting minutes are associated with choices involving reduced decision ambivalence. Thus, on this slow time scale, sympathetic drive serves as a proxy for "mobilization" whereby participants are more likely to show consistent value-action mapping. In parallel, imaging analyses reveal that on shorter time scales (estimated with a trial-to-trial GLM), increased vmPFC activity, particularly during low-ambivalence decisions, is associated with decreased sympathetic state. Our findings support a role of sympathetic drive in resolving decision ambivalence across long time horizons and suggest a potential role of vmPFC in modulating this response on a moment-to-moment basis.
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http://dx.doi.org/10.3389/fnbeh.2021.615796DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7937876PMC
February 2021

Late attentional processes potentially compensate for early perceptual multisensory integration deficits in children with autism: evidence from evoked potentials.

Sci Rep 2020 09 30;10(1):16157. Epub 2020 Sep 30.

Department of Child and Adolescent Psychiatry, Psychotherapy, and Psychosomatics, Medical Faculty, University of Freiburg, Hauptstrasse 8, 79104, Freiburg, Germany.

Sensory processing deficits and altered long-range connectivity putatively underlie Multisensory Integration (MSI) deficits in Autism Spectrum Disorder (ASD). The present study set out to investigate non-social MSI stimuli and their electrophysiological correlates in young neurotypical adolescents and adolescents with ASD. We report robust MSI effects at behavioural and electrophysiological levels. Both groups demonstrated normal behavioural MSI. However, at the neurophysiological level, the ASD group showed less MSI-related reduction of the visual P100 latency, greater MSI-related slowing of the auditory P200 and an overall temporally delayed and spatially constrained onset of MSI. Given the task design and patient sample, and the age of our participants, we argue that electro-cortical indices of MSI deficits in ASD: (a) can be detected in early-adolescent ASD, (b) occur at early stages of perceptual processing, (c) can possibly be compensated by later attentional processes, (d) thus leading to normal MSI at the behavioural level.
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http://dx.doi.org/10.1038/s41598-020-73022-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7527489PMC
September 2020

Sympathetic involvement in time-constrained sequential foraging.

Cogn Affect Behav Neurosci 2020 08;20(4):730-745

Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106, USA.

Appraising sequential offers relative to an unknown future opportunity and a time cost requires an optimization policy that draws on a learned estimate of an environment's richness. Converging evidence points to a learning asymmetry, whereby estimates of this richness update with a bias toward integrating positive information. We replicate this bias in a sequential foraging (prey selection) task and probe associated activation within the sympathetic branch of the autonomic system, using trial-by-trial measures of simultaneously recorded cardiac autonomic physiology. We reveal a unique adaptive role for the sympathetic branch in learning. It was specifically associated with adaptation to a deteriorating environment: it correlated with both the rate of negative information integration in belief estimates and downward changes in moment-to-moment environmental richness, and was predictive of optimal performance on the task. The findings are consistent with a framework whereby autonomic function supports the learning demands of prey selection.
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http://dx.doi.org/10.3758/s13415-020-00799-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7651516PMC
August 2020

Electro-cortical correlates of multisensory integration using ecologically valid emotional stimuli: Differential effects for fear and disgust.

Biol Psychol 2019 03 24;142:132-139. Epub 2019 Jan 24.

Department of Child and Adolescent Psychiatry, Psychotherapy, and Psychosomatics, Faculty of Medicine, University of Freiburg, Germany; Department of Psychiatry, National and Kapodistrian University of Athens, Medical School, Athens, Greece; Department of Child and Adolescent Psychiatry, Medical Faculty, University of Cologne, Germany. Electronic address:

Multisensory integration (MSI) is crucial for human communication and social interaction and has been investigated in healthy populations and neurodevelopmental disorders. However, the use of stimuli with high ecological validity is sparse, especially in event-related potential (ERP) studies. The present study examined the ERP correlates of MSI in healthy adults using short (500 ms) ecologically valid professional actor-produced emotions of fear or disgust as vocal exclamation or facial expression (unimodal conditions) or both (bimodal condition). Behaviourally, our results show a general visual dominance effect (similarly fast responses following bimodal and visual stimuli) and an MSI-related speedup of responses only for fear. Electrophysiologically, both P100 and N170 showed MSI-related amplitude increases only following fear, but not disgust stimuli. Our results show for the first time that the known differential neural processing of fear and disgust also holds for the integration of dynamic auditory and visual information.
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http://dx.doi.org/10.1016/j.biopsycho.2019.01.011DOI Listing
March 2019

Early sensitivity of evoked potentials to surface and volumetric structure during the visual perception of three-dimensional object shape.

Eur J Neurosci 2020 12 26;52(11):4453-4467. Epub 2018 Dec 26.

School of Psychology, University of Queensland, Saint Lucia, Qld, Australia.

This study used event-related potentials (ERPs) to elucidate how the human visual system processes three-dimensional (3-D) object shape structure. In particular, we examined whether the perceptual mechanisms that support the analysis of 3-D shape are differentially sensitive to higher order surface and volumetric part structure. Observers performed a whole-part novel object matching task in which part stimuli comprised sub-regions of closed edge contour, surfaces or volumetric parts. Behavioural response latency data showed an advantage in matching surfaces and volumetric parts to whole objects over contours, but no difference between surfaces and volumes. ERPs were analysed using a convergence of approaches based on stimulus dependent amplitude modulations of evoked potentials, topographic segmentation, and spatial frequency oscillations. The results showed early differential perceptual processing of contours, surfaces, and volumetric part stimuli. This was first reliably observed over occipitoparietal electrodes during the N1 (140-200 ms) with a mean peak latency of 170 ms, and continued on subsequent P2 (220-260 ms) and N2 (260-320 ms) components. The differential sensitivity in perceptual processing during the N1 was accompanied by distinct microstate patterns that distinguished among contours, surfaces and volumes, and predominant theta band activity around 4-7 Hz over right occipitoparietal and orbitofrontal sites. These results provide the first evidence of early differential perceptual processing of higher order surface and volumetric shape structure within the first 200 ms of stimulus processing. The findings challenge theoretical models of object recognition that do not attribute functional significance to surface and volumetric object structure during visual perception.
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http://dx.doi.org/10.1111/ejn.14270DOI Listing
December 2020

The neural basis of hand choice: An fMRI investigation of the Posterior Parietal Interhemispheric Competition model.

Neuroimage 2019 01 17;185:208-221. Epub 2018 Oct 17.

School of Psychology, Bangor University, Bangor, UK. Electronic address:

The current study investigates a new neurobiological model of human hand choice: The Posterior Parietal Interhemispheric Competition (PPIC) model. The model specifies that neural populations in bilateral posterior intraparietal and superior parietal cortex (pIP-SPC) encode actions in hand-specific terms, and compete for selection across and within hemispheres. Actions with both hands are encoded bilaterally, but the contralateral hand is overrepresented. We use a novel fMRI paradigm to test the PPIC model. Participants reach to visible targets while in the scanner, and conditions involving free choice of which hand to use (Choice) are compared with when hand-use is instructed. Consistent with the PPIC model, bilateral pIP-SPC is preferentially responsive for the Choice condition, and for actions made with the contralateral hand. In the right pIP-SPC, these effects include anterior intraparietal and superior parieto-occipital cortex. Left dorsal premotor cortex, and an area in the right lateral occipitotemporal cortex show the same response pattern, while the left inferior parietal lobule is preferentially responsive for the Choice condition and when using the ipsilateral hand. Behaviourally, hand choice is biased by target location - for targets near the left/right edges of the display, the hand in ipsilateral hemispace is favoured. Moreover, consistent with a competitive process, response times are prolonged for choices to more ambiguous targets, where hand choice is relatively unbiased, and fMRI responses in bilateral pIP-SPC parallel this pattern. Our data provide support for the PPIC model, and reveal a selective network of brain areas involved in free hand choice, including bilateral posterior parietal cortex, left-lateralized inferior parietal and dorsal premotor cortices, and the right lateral occipitotemporal cortex.
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http://dx.doi.org/10.1016/j.neuroimage.2018.10.039DOI Listing
January 2019

Now and then: Hand choice is influenced by recent action history.

Psychon Bull Rev 2019 Feb;26(1):305-314

Brain Imaging Center, Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, USA.

Action choices are influenced by recent past and predicted future action states. Here, we demonstrate that recent hand-choice history affects both current hand choices and response times to initiate actions. Participants reach to contact visible targets using one hand. Hand choice is biased in favour of which hand was used recently, in particular, when the biomechanical costs of responding with either hand are similar, and repeated choices lead to reduced response times. These effects are also found to positively correlate. Participants who show strong effects of recent history on hand choice also tend to show strong effects of recent history on response times. The data are consistent with a computational efficiency interpretation whereby repeated action choices confer computational gains in the efficiency of underpinning processes. We discuss our results within the framework of this model, and with respect to balancing predicted gains and losses, and speculate about the possible underlying mechanisms in neural terms.
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http://dx.doi.org/10.3758/s13423-018-1510-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6424939PMC
February 2019

Effects of caffeine on reaction time are mediated by attentional rather than motor processes.

Psychopharmacology (Berl) 2018 03 23;235(3):749-759. Epub 2017 Dec 23.

North Wales Clinical Psychology Programme, School of Psychology, Bangor University, Adeilad Brigantia, Ffordd Penrallt, Bangor, Gwynedd, Wales, LL57 2AS, UK.

Background: Caffeine has a well-established effect on reaction times (RTs) but the neurocognitive mechanisms underlying this are unclear.

Methods: In the present study, 15 female participants performed an oddball task after ingesting caffeine or a placebo, and electroencephalographic data were obtained. Single-trial P3b latencies locked to the stimulus and to the response were extracted and mediation models were fitted to the data to test whether caffeine's effect on RTs was mediated by its effect on either type of P3b latencies.

Results: Stimulus-locked latencies showed clear evidence of mediation, with approximately a third of the effect of caffeine on RTs running through the processes measured by stimulus-locked latencies. Caffeine did not affect response-locked latencies, so could not mediate the effect.

Discussion: These findings are consistent with caffeine's effect on RTs being a result of its effect on perceptual-attentional processes, rather than motor processes. The study is the first to apply mediation analysis to single-trial P3b data and this technique holds promise for mental chronometric studies into the effects of psychopharmacological agents. The R code for performing the single trial analysis and mediation analysis are included as supplementary materials.
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http://dx.doi.org/10.1007/s00213-017-4790-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847000PMC
March 2018

Human Parahippocampal Cortex Supports Spatial Binding in Visual Working Memory.

Cereb Cortex 2018 10;28(10):3589-3599

School of Psychology, Bangor University, Bangor, UK.

Studies investigating the functional organization of the medial temporal lobe (MTL) suggest that parahippocampal cortex (PHC) generates representations of spatial and contextual information used by the hippocampus in the formation of episodic memories. However, evidence from animal studies also implicates PHC in spatial binding of visual information held in short term, working memory. Here we examined a 46-year-old man (P.J.), after he had recovered from bilateral medial occipitotemporal cortex strokes resulting in ischemic lesions of PHC and hippocampal atrophy, and a group of age-matched healthy controls. When recalling the color of 1 of 2 objects, P.J. misidentified the target when cued by its location, but not shape. When recalling the position of 1 of 3 objects, he frequently misidentified the target, which was cued by its color. Increasing the duration of the memory delay had no impact on the proportion of binding errors, but did significantly worsen recall precision in both P.J. and controls. We conclude that PHC may play a crucial role in spatial binding during encoding of visual information in working memory.
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http://dx.doi.org/10.1093/cercor/bhx231DOI Listing
October 2018

Multisensory stimulation in hemianopic patients boosts orienting responses to the hemianopic field and reduces attentional resources to the intact field.

Restor Neurol Neurosci 2015 ;33(4):405-19

Department of Psychology, University of Bologna, Bologna, Italy.

Purpose: Lateralised lesions can disrupt inhibitory cross-callosal fibres which maintain interhemispheric equilibrium in attention networks, with a consequent attentional bias towards the ipsilesional field. Some evidence of this imbalance has also been found in hemianopic patients (Tant et al., 2002). The aim of the present study was to reduce this attentional bias in hemianopic patients by using multisensory stimulation capable of activating subcortical structures responsible for orienting attention, such as the superior colliculus.

Methods: Eight hemianopic patients underwent a course of multisensory stimulation treatment for two weeks and their behavioural and electrophysiological performance was tested at three time intervals: baseline 1 (before treatment), control baseline 2 (two weeks after baseline 1 and immediately before treatment as a control for practice effects) and finally after treatment.

Results: The results show improvements on various clinical measures, on orienting responses in the hemianopic field, and a reduction of electrophysiological activity (P3 amplitude) in response to stimuli presented in the intact visual field.

Conclusions: These results suggest that the primary visual deficit in hemianopic patients might be accompanied by an ipsilesional attentional bias which might be reduced by multisensory stimulation.
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http://dx.doi.org/10.3233/RNN-140457DOI Listing
June 2016

Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings.

Front Behav Neurosci 2015 27;9:192. Epub 2015 Jul 27.

Medical Faculty, Institute of Medical Psychology, Otto-von-Guericke University of Magdeburg Magdeburg, Germany.

Neuropsychological training methods of visual rehabilitation for homonymous vision loss caused by postchiasmatic damage fall into two fundamental paradigms: "compensation" and "restoration". Existing methods can be classified into three groups: Visual Scanning Training (VST), Audio-Visual Scanning Training (AViST) and Vision Restoration Training (VRT). VST and AViST aim at compensating vision loss by training eye scanning movements, whereas VRT aims at improving lost vision by activating residual visual functions by training light detection and discrimination of visual stimuli. This review discusses the rationale underlying these paradigms and summarizes the available evidence with respect to treatment efficacy. The issues raised in our review should help guide clinical care and stimulate new ideas for future research uncovering the underlying neural correlates of the different treatment paradigms. We propose that both local "within-system" interactions (i.e., relying on plasticity within peri-lesional spared tissue) and changes in more global "between-system" networks (i.e., recruiting alternative visual pathways) contribute to both vision restoration and compensatory rehabilitation, which ultimately have implications for the rehabilitation of cognitive functions.
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http://dx.doi.org/10.3389/fnbeh.2015.00192DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4515568PMC
August 2015

Impaired auditory selective attention ameliorated by cognitive training with graded exposure to noise in patients with traumatic brain injury.

Neuropsychologia 2015 Aug 21;75:74-87. Epub 2015 May 21.

Trinity College Institute of Neuroscience, The University of Dublin, Dublin 2, Ireland. Electronic address:

Patients who suffer traumatic brain injury frequently report difficulty concentrating on tasks and completing routine activities in noisy and distracting environments. Such impairments can have long-term negative psychosocial consequences. A cognitive control function that may underlie this impairment is the capacity to select a goal-relevant signal for further processing while safeguarding it from irrelevant noise. A paradigmatic investigation of this problem was undertaken using a dichotic listening task (study 1) in which comprehension of a stream of speech to one ear was measured in the context of increasing interference from a second stream of irrelevant speech to the other ear. Controls showed an initial decline in performance in the presence of competing speech but thereafter showed adaptation to increasing audibility of irrelevant speech, even at the highest levels of noise. By contrast, patients showed linear decline in performance with increasing noise. Subsequently attempts were made to ameliorate this deficit (study 2) using a cognitive training procedure based on attention process training (APT) that included graded exposure to irrelevant noise over the course of training. Patients were assigned to adaptive and non-adaptive training schedules or to a no-training control group. Results showed that both types of training drove improvements in the dichotic listening and in naturalistic tasks of performance in noise. Improvements were also seen on measures of selective attention in the visual domain suggesting transfer of training. We also observed augmentation of event-related potentials (ERPs) linked to target processing (P3b) but no change in ERPs evoked by distractor stimuli (P3a) suggesting that training heightened tuning of target signals, as opposed to gating irrelevant noise. No changes in any of the above measures were observed in a no-training control group. Together these findings present an ecologically valid approach to measure selective attention difficulties after brain injury, and provide a means to ameliorate these deficits.
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http://dx.doi.org/10.1016/j.neuropsychologia.2015.05.012DOI Listing
August 2015

When apperceptive agnosia is explained by a deficit of primary visual processing.

Cortex 2014 Mar 31;52:12-27. Epub 2013 Dec 31.

CsrNC, Centro studi e ricerche in Neuroscienze Cognitive, Polo Scientifico-Didattico di Cesena, ALMA MATER STUDIORUM - Università di Bologna, Italy; Dipartimento di Psicologia, ALMA MATER STUDIORUM - Università di Bologna, Italy. Electronic address:

Visual agnosia is a deficit in shape perception, affecting figure, object, face and letter recognition. Agnosia is usually attributed to lesions to high-order modules of the visual system, which combine visual cues to represent the shape of objects. However, most of previously reported agnosia cases presented visual field (VF) defects and poor primary visual processing. The present case-study aims to verify whether form agnosia could be explained by a deficit in basic visual functions, rather that by a deficit in high-order shape recognition. Patient SDV suffered a bilateral lesion of the occipital cortex due to anoxia. When tested, he could navigate, interact with others, and was autonomous in daily life activities. However, he could not recognize objects from drawings and figures, read or recognize familiar faces. He was able to recognize objects by touch and people from their voice. Assessments of visual functions showed blindness at the centre of the VF, up to almost 5°, bilaterally, with better stimulus detection in the periphery. Colour and motion perception was preserved. Psychophysical experiments showed that SDV's visual recognition deficits were not explained by poor spatial acuity or by the crowding effect. Rather a severe deficit in line orientation processing might be a key mechanism explaining SDV's agnosia. Line orientation processing is a basic function of primary visual cortex neurons, necessary for detecting "edges" of visual stimuli to build up a "primal sketch" for object recognition. We propose, therefore, that some forms of visual agnosia may be explained by deficits in basic visual functions due to widespread lesions of the primary visual areas, affecting primary levels of visual processing.
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http://dx.doi.org/10.1016/j.cortex.2013.12.011DOI Listing
March 2014