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  1. Artikel ; Online: Distractors Selectively Modulate Electrophysiological Markers of Perceptual Decisions.

    Zhou, Shou-Han / Loughnane, Gerard / O'Connell, Redmond / Bellgrove, Mark A / Chong, Trevor T-J

    Journal of cognitive neuroscience

    2021  Band 33, Heft 6, Seite(n) 1020–1031

    Abstract: Current models of perceptual decision-making assume that choices are made after evidence in favor of an alternative accumulates to a given threshold. This process has recently been revealed in human EEG recordings, but an unresolved issue is how these ... ...

    Abstract Current models of perceptual decision-making assume that choices are made after evidence in favor of an alternative accumulates to a given threshold. This process has recently been revealed in human EEG recordings, but an unresolved issue is how these neural mechanisms are modulated by competing, yet task-irrelevant, stimuli. In this study, we tested 20 healthy participants on a motion direction discrimination task. Participants monitored two patches of random dot motion simultaneously presented on either side of fixation for periodic changes in an upward or downward motion, which could occur equiprobably in either patch. On a random 50% of trials, these periods of coherent vertical motion were accompanied by simultaneous task-irrelevant, horizontal motion in the contralateral patch. Our data showed that these distractors selectively increased the amplitude of early target selection responses over scalp sites contralateral to the distractor stimulus, without impacting on responses ipsilateral to the distractor. Importantly, this modulation mediated a decrement in the subsequent buildup rate of a neural signature of evidence accumulation and accounted for a slowing of RTs. These data offer new insights into the functional interactions between target selection and evidence accumulation signals, and their susceptibility to task-irrelevant distractors. More broadly, these data neurally inform future models of perceptual decision-making by highlighting the influence of early processing of competing stimuli on the accumulation of perceptual evidence.
    Mesh-Begriff(e) Attention ; Humans
    Sprache Englisch
    Erscheinungsdatum 2021-08-20
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1007410-7
    ISSN 1530-8898 ; 0898-929X ; 1096-8857
    ISSN (online) 1530-8898
    ISSN 0898-929X ; 1096-8857
    DOI 10.1162/jocn_a_01703
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  2. Artikel ; Online: A neural index of inefficient evidence accumulation in dyslexia underlying slow perceptual decision making.

    Stefanac, Nicole R / Zhou, Shou-Han / Spencer-Smith, Megan M / O'Connell, Redmond / Bellgrove, Mark A

    Cortex; a journal devoted to the study of the nervous system and behavior

    2021  Band 142, Seite(n) 122–137

    Abstract: Visual processing deficits have been widely reported in developmental dyslexia however the locus of cognitive dysfunction remains unclear. Here, we examined the neural correlates of perceptual decision-making using a dot-motion task and ... ...

    Abstract Visual processing deficits have been widely reported in developmental dyslexia however the locus of cognitive dysfunction remains unclear. Here, we examined the neural correlates of perceptual decision-making using a dot-motion task and electroencephalography (EEG) and investigated whether presenting deficits were unique to children with dyslexia or if they were also evident in other, typically developing children with equally immature reading systems. Sixty-eight children participated: 32 with dyslexia (DD; 16 females); 21 age-matched controls (AM; 11 females) and 15 reading-matched controls (RM; 9 females). All participants completed a bilaterally presented random-dot-motion task while EEG was recorded. Neural signatures of low level sensory processing (steady state visual evoked potentials; SSVEPs), pre-target attentional bias (posterior α power), attentional orienting (N2), evidence accumulation (centro-parietal positive decision signal; CPP) and execution of a motor response (β) were obtained to dissect the temporal sequence of perceptual decision-making. Reading profile provided a score of relative lexical and sublexical skills for each participant. Although all groups performed comparably in terms of task accuracy and false alarm rate, the DD group were slower and demonstrated an earlier peak latency, reduced slope and lower amplitude of the CPP compared with both AM and RM controls. Reading profile was found to moderate the relationship between word reading ability, reaction time as well as CPP indices showing that lexical dyslexics responded more slowly and had a shallower slope, reduced amplitude and earlier latency of CPP waveforms than sublexical dyslexics. These findings suggest that children with dyslexia, particularly those with relatively poorer lexical abilities, have a reduced rate and peak of evidence accumulation as denoted by CPP markers yet remain slow in their overt response. This is in keeping with hypotheses that children with dyslexia have impairment in effectively sampling and processing evidence about visual motion stimuli.
    Sprache Englisch
    Erscheinungsdatum 2021-06-24
    Erscheinungsland Italy
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 280622-8
    ISSN 1973-8102 ; 0010-9452
    ISSN (online) 1973-8102
    ISSN 0010-9452
    DOI 10.1016/j.cortex.2021.05.021
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  3. Artikel ; Online: Acute exercise as a modifier of neocortical plasticity and aperiodic activity in the visual cortex.

    Cadwallader, Claire J / Steiniger, Jennifer / Cooper, Patrick S / Zhou, Shou-Han / Hendrikse, Joshua / Sumner, Rachael L / Kirk, Ian J / Chong, Trevor T-J / Coxon, James P

    Scientific reports

    2023  Band 13, Heft 1, Seite(n) 7491

    Abstract: Long-term potentiation (LTP) is a form of neuroplasticity commonly implicated in mechanistic models of learning and memory. Acute exercise can boost LTP in the motor cortex, and is associated with a shift in excitation/inhibition (E:I) balance, but ... ...

    Abstract Long-term potentiation (LTP) is a form of neuroplasticity commonly implicated in mechanistic models of learning and memory. Acute exercise can boost LTP in the motor cortex, and is associated with a shift in excitation/inhibition (E:I) balance, but whether this extends to other regions such as the visual cortex is unknown. We investigated the effect of a preceding bout of exercise on LTP induction and the E:I balance in the visual cortex using electroencephalography (EEG). Young adults (N = 20, mean age = 24.20) engaged in 20 min of high-intensity interval training (HIIT) exercise and rest across two counterbalanced sessions. LTP was induced using a high frequency presentation of a visual stimulus; a "visual tetanus". Established EEG markers of visual LTP, the N1b and P2 component of the visual evoked potential, and an EEG-derived measure of the E:I balance, the aperiodic exponent, were measured before and after the visual tetanus. As expected, there was a potentiation of the N1b following the visual tetanus, with specificity to the tetanised stimulus, and a non-specific potentiation of the P2. These effects were not sensitive to a preceding bout of exercise. However, the E:I balance showed a late shift towards inhibition following the visual tetanus. A preceding bout of exercise resulted in specificity of this E:I balance shift to the tetanised stimulus, that was not seen following rest. This novel finding suggests a possible exercise-induced tuning of the visual cortex to stimulus details following LTP induction.
    Mesh-Begriff(e) Young Adult ; Humans ; Adult ; Evoked Potentials, Visual ; Neocortex ; Tetanus ; Exercise ; Visual Cortex
    Sprache Englisch
    Erscheinungsdatum 2023-05-09
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-34749-w
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  4. Artikel ; Online: Evidence Accumulation Rate Moderates the Relationship between Enriched Environment Exposure and Age-Related Response Speed Declines.

    Brosnan, Méadhbh / Pearce, Daniel J / O'Neill, Megan H / Loughnane, Gerard M / Fleming, Bryce / Zhou, Shou-Han / Chong, Trevor / Nobre, Anna C / O Connell, Redmond G / Bellgrove, Mark A

    The Journal of neuroscience : the official journal of the Society for Neuroscience

    2023  Band 43, Heft 37, Seite(n) 6401–6414

    Abstract: Older adults exposed to enriched environments (EEs) maintain relatively higher levels of cognitive function, even in the face of compromised markers of brain health. Response speed (RS) is often used as a simple proxy to measure the preservation of ... ...

    Abstract Older adults exposed to enriched environments (EEs) maintain relatively higher levels of cognitive function, even in the face of compromised markers of brain health. Response speed (RS) is often used as a simple proxy to measure the preservation of global cognitive function in older adults. However, it is unknown which specific selection, decision, and/or motor processes provide the most specific indices of neurocognitive health. Here, using a simple decision task with electroencephalography (EEG), we found that the efficiency with which an individual accumulates sensory evidence was a critical determinant of the extent to which RS was preserved in older adults (63% female, 37% male). Moreover, the mitigating influence of EE on age-related RS declines was most pronounced when evidence accumulation rates were shallowest. These results suggest that the phenomenon of cognitive reserve, whereby high EE individuals can better tolerate suboptimal brain health to facilitate the preservation of cognitive function, is not just applicable to neuroanatomical indicators of brain aging but can be observed in markers of neurophysiology. Our results suggest that EEG metrics of evidence accumulation may index neurocognitive vulnerability of the aging brain.
    Mesh-Begriff(e) Humans ; Male ; Female ; Aged ; Reaction Time ; Brain/physiology ; Cognition/physiology ; Aging ; Electroencephalography/methods
    Sprache Englisch
    Erscheinungsdatum 2023-07-28
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 604637-x
    ISSN 1529-2401 ; 0270-6474
    ISSN (online) 1529-2401
    ISSN 0270-6474
    DOI 10.1523/JNEUROSCI.2260-21.2023
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  5. Artikel ; Online: Dopamine restores cognitive motivation in Parkinson's disease.

    McGuigan, Sara / Zhou, Shou-Han / Brosnan, Méadhbh B / Thyagarajan, Dominic / Bellgrove, Mark A / Chong, Trevor T-J

    Brain : a journal of neurology

    2019  Band 142, Heft 3, Seite(n) 719–732

    Abstract: Disorders of motivation, such as apathy, are common in Parkinson's disease, and a key feature of such disorders is a greater aversion to effort. In humans, the experience of cognitive effort is ubiquitous, and cognitive apathy has traditionally been ... ...

    Abstract Disorders of motivation, such as apathy, are common in Parkinson's disease, and a key feature of such disorders is a greater aversion to effort. In humans, the experience of cognitive effort is ubiquitous, and cognitive apathy has traditionally been considered distinct and separable from other subtypes. Surprisingly, however, the neurobiology of cognitive motivation is poorly understood. In particular, although dopamine has a well-characterized role in incentivizing physically effortful behaviour, a critical, unresolved issue is whether its facilitatory role generalizes to other domains. Here, we asked how dopamine modulates the willingness of patients with Parkinson's disease to invest cognitive effort in return for reward. We tested 20 patients with idiopathic Parkinson's disease across two counterbalanced sessions-ON and OFF their usual dopaminergic medication-and compared their performance to 20 healthy age-matched controls. We applied a novel task in which we manipulated cognitive effort as the number of rapid serial visual presentation streams to which participants had to attend. After training participants to ceiling performance, we then asked them to choose between a low-effort/low-reward baseline option, and a higher-effort/higher-reward offer. Computational models of choice behaviour revealed four key results. First, patients OFF medication were significantly less cognitively motivated than controls, as manifest by steeper cognitive effort discounting functions in the former group. Second, dopaminergic therapy improved this deficit, such that choices in patients ON medication were indistinguishable from controls. Third, differences in motivation were also accompanied by independent changes in the stochasticity of individuals' decisions, such that dopamine reduced the variability in choice behaviour. Finally, choices on our task correlated uniquely with the subscale of the Dimensional Apathy Scale that specifically indexes cognitive motivation, which suggests a close relationship between our laboratory measure of cognitive effort discounting and subjective reports of day-to-day cognitive apathy. Importantly, participants' choices were not confounded by temporal discounting, probability discounting, physical demand, or varying task performance. These results are the first to reveal the central role of dopamine in overcoming cognitive effort costs. They provide an insight into the computational mechanisms underlying cognitive apathy in Parkinson's disease, and demonstrate its amenability to dopaminergic therapy. More broadly, they offer important empirical support for prominent frameworks proposing a domain-general role for dopamine in value-based decision-making, and provide a critical link between dopamine and multidimensional theories of apathy.
    Mesh-Begriff(e) Aged ; Apathy ; Cognition/drug effects ; Computer Simulation ; Decision Making ; Dopamine/metabolism ; Dopamine/pharmacology ; Dopamine Agents/therapeutic use ; Female ; Humans ; Male ; Middle Aged ; Motivation/drug effects ; Parkinson Disease/drug therapy ; Physical Exertion ; Reward
    Chemische Substanzen Dopamine Agents ; Dopamine (VTD58H1Z2X)
    Sprache Englisch
    Erscheinungsdatum 2019-01-28
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80072-7
    ISSN 1460-2156 ; 0006-8950
    ISSN (online) 1460-2156
    ISSN 0006-8950
    DOI 10.1093/brain/awy341
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  6. Artikel ; Online: Effect of sensory experience on motor learning strategy.

    Zhou, Shou-Han / Oetomo, Denny / Tan, Ying / Mareels, Iven / Burdet, Etienne

    Journal of neurophysiology

    2015  Band 113, Heft 4, Seite(n) 1077–1084

    Abstract: It is well known that the central nervous system automatically reduces a mismatch in the visuomotor coordination. Can the underlying learning strategy be modified by environmental factors or a subject's learning experiences? To elucidate this matter, two ...

    Abstract It is well known that the central nervous system automatically reduces a mismatch in the visuomotor coordination. Can the underlying learning strategy be modified by environmental factors or a subject's learning experiences? To elucidate this matter, two groups of subjects learned to execute reaching arm movements in environments with task-irrelevant visual cues. However, one group had previous experience of learning these movements using task-relevant visual cues. The results demonstrate that the two groups used different learning strategies for the same visual environment and that the learning strategy was influenced by prior learning experience.
    Mesh-Begriff(e) Brain/physiology ; Cues ; Female ; Hand/innervation ; Hand/physiology ; Humans ; Learning ; Male ; Motor Skills ; Sensation ; Young Adult
    Sprache Englisch
    Erscheinungsdatum 2015-02-15
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    DOI 10.1152/jn.00470.2014
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  7. Artikel ; Online: Modeling individual human motor behavior through model reference iterative learning control.

    Zhou, Shou-Han / Oetomo, Denny / Tan, Ying / Burdet, Etienne / Mareels, Iven

    IEEE transactions on bio-medical engineering

    2012  Band 59, Heft 7, Seite(n) 1892–1901

    Abstract: A computational model is proposed in this paper to capture learning capacity of a human subject adapting his or her movements in novel dynamics. The model uses an iterative learning control algorithm to represent human learning through repetitive ... ...

    Abstract A computational model is proposed in this paper to capture learning capacity of a human subject adapting his or her movements in novel dynamics. The model uses an iterative learning control algorithm to represent human learning through repetitive processes. The control law performs adaptation using a model designed using experimental data captured from the natural behavior of the individual of interest. The control signals are used by a model of the body to produced motion without the need of inverse kinematics. The resulting motion behavior is validated against experimental data. This new technique yields the capability of subject-specific modeling of the motor function, with the potential to explain individual behavior in physical rehabilitation.
    Mesh-Begriff(e) Algorithms ; Biomechanical Phenomena ; Computer Simulation ; Humans ; Learning/physiology ; Locomotion/physiology ; Models, Biological ; Reproducibility of Results
    Sprache Englisch
    Erscheinungsdatum 2012-07
    Erscheinungsland United States
    Dokumenttyp Journal Article
    ZDB-ID 160429-6
    ISSN 1558-2531 ; 0018-9294
    ISSN (online) 1558-2531
    ISSN 0018-9294
    DOI 10.1109/TBME.2012.2192437
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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