Redmond O'Connell

Redmond O'Connell
Trinity College Dublin | TCD · Institute of Neuroscience

PhD

About

82
Publications
24,724
Reads
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4,643
Citations
Additional affiliations
July 2013 - present
Monash University (Australia)
Position
  • Adjunct Senior Research Fellow
September 2011 - present
Trinity College Dublin
Position
  • Professor (Assistant)
September 2011 - present
Trinity College
Position
  • Professor (Assistant)

Publications

Publications (82)
Article
Computational and neurophysiological research has highlighted neural processes that accumulate sensory evidence for perceptual decisions [1]. These processes have been studied in the context of highly simplified perceptual discrimination paradigms in which the physical evidence appears at times and locations that are either entirely predictable or...
Data
Full-text available
The P300 component of the human event-related potential has been the subject of intensive experimental investigation across a five-decade period, owing to its apparent relevance to a wide range of cognitive functions and its sensitivity to numerous brain disorders, yet its exact contribution to cognition remains unresolved. Here, we carry out key a...
Article
In the last two decades, animal neurophysiology research has made great strides towards explaining how the brain can enable adaptive action in the face of noisy sensory information. In particular, this work has identified neural signals that perform the role of a 'decision variable' which integrates sensory information in favor of a particular outc...
Article
The locus coeruleus-noradrenergic (LC–NA) neuromodulatory system has been implicated in a broad array of cognitive processes, yet scope for investigating this system’s function in humans is currently limited by an absence of reliable non-invasive measures of LC activity. Although pupil diameter has been employed as a proxy measure of LC activity in...
Article
Sustained attention describes our ability to keep a constant focus on a given task. This ability is modulated by our physiological state of arousal. Although lapses of sustained attention have been linked with dysregulations of arousal, the underlying physiological mechanisms remain unclear. An emerging body of work proposes that the intrusion duri...
Preprint
Full-text available
Decisions about noisy stimuli are widely understood to be made by accumulating evidence up to a decision bound that can be adjusted according to task demands. However, relatively little is known about how such mechanisms operate in continuous monitoring contexts requiring intermittent target detection. Here, we examined neural decision processes un...
Preprint
Sustained attention describes our ability to keep a constant focus on a given task. This ability is modulated by our physiological state of arousal. Although lapses of sustained attention have been linked with dysregulations of arousal, the underlying physiological mechanisms remain unclear. An emerging body of work proposes that the intrusion duri...
Preprint
Older adults exposed to enriched environments (EE) 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 sensory, decision, an...
Article
The discovery of neural signals that reflect the dynamics of perceptual decision formation has had a considerable impact. Not only do such signals enable detailed investigations of the neural implementation of the decision-making process but they also can expose key elements of the brain's decision algorithms. For a long time, such signals were onl...
Article
Full-text available
To interact successfully with diverse sensory environments, we must adapt our decision processes to account for time constraints and prior probabilities. The full set of decision-process parameters that undergo such flexible adaptation has proven to be difficult to establish using simplified models that are based on behaviour alone. Here, we utiliz...
Preprint
Full-text available
Perceptual decisions are biased toward higher-value options when overall gains can be improved. When stimuli demand immediate reactions, the neurophysiological decision process dynamically evolves through distinct phases of growing anticipation, detection and discrimination, but how value biases are exerted through these phases remains unknown. Her...
Article
Full-text available
Animal neurophysiological studies have identified neural signals within dorsal frontoparietal areas that trace a perceptual decision by accumulating sensory evidence over time and trigger action upon reaching a threshold. Although analogous accumulation-to-bound signals are identifiable on extracranial human electroencephalography, their cortical o...
Article
Full-text available
For many years, the dominant theoretical framework guiding research into the neural origins of perceptual experience has been provided by hierarchical feedforward models, in which sensory inputs are passed through a series of increasingly complex feature detectors. However, the long‐standing orthodoxy of these accounts has recently been challenged...
Article
Full-text available
The computations and neural processes underpinning decision making have primarily been investigated using highly simplified tasks in which stimulus onsets cue observers to start accumulating choice-relevant information. Yet, in daily life we are rarely afforded the luxury of knowing precisely when choice-relevant information will appear. Here, we e...
Preprint
Full-text available
When selecting actions in response to noisy sensory stimuli, the brain can exploit prior knowledge of time constraints, stimulus discriminability and stimulus probability to hone the decision process, but the full range of underlying neural process adjustments remains to be established. Here, we draw on human neurophysiological signals reflecting d...
Preprint
Full-text available
The computations and neural processes underpinning decision making have primarily been investigated using highly simplified tasks in which stimulus onsets cue observers to start accumulating choice-relevant information. Yet, in daily life we are rarely afforded the luxury of knowing precisely when choice-relevant information will appear. Here, we e...
Article
Full-text available
The timing and accuracy of perceptual decision-making is exquisitely sensitive to fluctuations in arousal. Although extensive research has highlighted the role of various neural processing stages in forming decisions, our understanding of how arousal impacts these processes remains limited. Here we isolated electrophysiological signatures of decisi...
Article
Recent behavioral modeling and pupillometry studies suggest that neuromodulatory arousal systems play a role in regulating decision formation but neurophysiological support for these observations is lacking. We employed a randomized, double-blinded, placebo-controlled, crossover design to probe the impact of pharmacological enhancement of catechola...
Article
Full-text available
Ageing impacts on decision-making behaviour across a range of cognitive tasks and scenarios. Computational modelling has proved valuable in providing mechanistic interpretations of these age-related differences; however, the extent to which model parameter differences accurately reflect changes to the underlying neural computations remains unclear....
Preprint
Full-text available
Recent behavioural modelling and pupillometry studies suggest that neuromodulatory arousal systems play a role in regulating decision formation but neurophysiological support for these observations is lacking. We employed a randomised, double-blinded, placebo-controlled, crossover design to probe the impact of pharmacological enhancement of catecho...
Preprint
Full-text available
The timing and accuracy of perceptual decision making is exquisitely sensitive to fluctuations in arousal. Although extensive research has highlighted the role of neural evidence accumulation in forming decisions, our understanding of how arousal impacts these processes remains limited. Here we isolated electrophysiological signatures of evidence a...
Article
Full-text available
When decisions are made under speed pressure, "urgency" signals elevate neural activity toward action-triggering thresholds independent of the sensory evidence, thus incurring a cost to choice accuracy. While urgency signals have been observed in brain circuits involved in preparing actions, their influence at other levels of the sensorimotor pathw...
Article
The ability to sustain attention is integral to healthy cognition in aging. The right PFC (rPFC) is critical for maintaining high levels of attentional focus. Whether plasticity of this region can be harnessed to support sustained attention in older adults is unknown. We used transcranial direct current stimulation to increase cortical excitability...
Article
Highlights Sequential sampling models have been widely embraced in contemporary decision neuroscience. The models come in many forms that, despite containing fundamentally different algorithmic elements, can make highly similar predictions for behaviour. Consequently, it can be difficult to definitively adjudicate between alternative models based s...
Preprint
Full-text available
The locus coeruleus (LC) has established functions in both attention and respiration. Good attentional performance requires optimal levels of tonic LC activity, and must be matched to task consistently. LC neurons are chemosensitive, causing respiratory phrenic nerve firing to increase frequency with higher CO2 levels, and as CO2 level varies with...
Article
Despite their small size, microsaccades can impede stimulus detections if executed at inopportune times. Although it has been shown that microsaccades evoke both inhibitory and excitatory responses across different visual regions, their impact on the higher-level neural decision processes that bridge sensory responses to action selection has yet to...
Article
Full-text available
Limited resources for the in-depth processing of external stimuli make it necessary to select only relevant information from our surroundings and to ignore irrelevant stimuli. Attentional mechanisms facilitate this selection via top-down modulation of stimulus representations in the brain. Previous research has indicated that acetylcholine (ACh) mo...
Preprint
Full-text available
When decision makers prioritize speed over accuracy, neural activity is elevated in brain circuits involved in preparing actions. Such “urgency” signal components, defined by their independence from sensory evidence, are observed even before evidence is presented and can grow dynamically during decision formation. Is urgency applied globally, or ar...
Article
Recent work has demonstrated that explicit error detection relies on a neural evidence accumulation process that can be traced in the human electroencephalogram (EEG). Here, we sought to establish the impact of natural aging on this process by recording EEG from young (18-35 years) and older adults (65-88 years) during the performance of a Go/No-Go...
Article
Background Although it is well established that methylphenidate (MPH) enhances sustained attention, the neural mechanisms underpinning this improvement remain unclear. We examined how MPH influenced known electrophysiological (EEG) precursors of lapsing attention over different time-scales. Methods We measured the impact of MPH, compared with plac...
Article
Full-text available
Scientific Reports 6 : Article number: 27754 10.1038/srep27754 ; published online: 13 June 2016 ; updated: 23 March 2017 The Acknowledgements section in this Article is incomplete.
Article
Healthy subjects tend to exhibit a bias of visual attention whereby left hemifield stimuli are processed more quickly and accurately than stimuli appearing in the right hemifield. It has long been held that this phenomenon arises from the dominant role of the right cerebral hemisphere in regulating attention. However, methods that would enable more...
Article
Unlabelled: Electrophysiological research has isolated neural signatures of decision formation in a variety of brain regions. Studies in rodents and monkeys have focused primarily on effector-selective signals that translate the emerging decision into a specific motor plan, but, more recently, research on the human brain has identified an abstract...
Article
Brain networks subserving alertness in humans interact with those for spatial attention orienting. We employed blue-enriched light to directly manipulate alertness in healthy volunteers. We show for the first time that prior exposure to higher, relative to lower, intensities of blue-enriched light speeds response times to left, but not right, hemif...
Article
The P300 component of the human event-related potential has been the subject of intensive experimental investigation across a five-decade period, owing to its apparent relevance to a wide range of cognitive functions and its sensitivity to numerous brain disorders. Yet, its exact contribution to cognition remains unresolved. Here, we carry out key...
Article
Questionnaire-based demonstrations of impaired self-awareness (SA) after traumatic brain injury (TBI) are not always supported by experimental studies of in-the-moment or online awareness. This chapter begins by describing the clinical phenomenon of impaired SA, how it is measured, and why its interdependency with mechanisms of online awareness may...
Article
The authors regret that the following equation was reproduced incorrectly under Section 2.7 of the original article. The correct version is provided here: α asymmetry index ¼ right ROI α ð Þ Àleft ROI α ð Þ mean left and right ROI α ð Þ The authors would like to apologise for any inconvenience caused.
Article
Full-text available
The ability to detect errors during cognitive performance is compromised in older age and in a range of clinical populations. This study was designed to assess the effects of transcranial direct current stimulation (tDCS) on error awareness in healthy older human adults. tDCS was applied over DLPFC while subjects performed a computerized test of er...
Article
Full-text available
We frequently need to make timely decisions based on sensory evidence that is weak, ambiguous, or noisy resulting from conditions in the external environment (e.g., a cluttered visual scene) or within the brain itself (e.g., inattention, neural noise). Here we examine how externally and internally driven variations in the quality of sensory evidenc...
Article
Full-text available
Poor recognition of the degree or scope of one's own cognitive deficits is a common feature of many neurological conditions, including diseases of aging, but little is known about the impact the natural aging process has on this aspect of self-awareness (SA). Here, a group of 45 healthy older adults and a comparison group of 45 young adults complet...
Article
Full-text available
Error processing is a critical executive function that is impaired in a large number of clinical populations. Although the neural underpinnings of this function have been investigated for decades and critical error-related components in the human electroencephalogram (EEG), such as the error-related negativity (ERN) and the error positivity (Pe), h...
Article
Resting fluctuations in the blood oxygenation level-dependent signal have attracted considerable interest for their sensitivity to pathological brain processes. However, these analyses are susceptible to confound by nonneural physiological factors such as vasculature, breathing, and head movement which is a concern when investigating elderly or pat...
Article
Full-text available
In theoretical accounts of perceptual decision-making, a decision variable integrates noisy sensory evidence and determines action through a boundary-crossing criterion. Signals bearing these very properties have been characterized in single neurons in monkeys, but have yet to be directly identified in humans. Using a gradual target detection task,...
Article
A number of recent studies suggest that DNA variation in the dopamine transporter gene (DAT1) influences spatial attention asymmetry in clinical populations such as ADHD, but confirmation in non-clinical samples is required. Since non-spatial factors such as attentional load have been shown to influence spatial biases in clinical conditions, here w...
Article
Full-text available
Recent electrophysiological research has sought to elucidate the neural mechanisms necessary for the conscious awareness of action errors. Much of this work has focused on the error positivity (Pe), a neural signal that is specifically elicited by errors that have been consciously perceived. While awareness appears to be an essential prerequisite f...
Article
Full-text available
How the brain monitors ongoing behavior for performance errors is a central question of cognitive neuroscience. Diminished awareness of performance errors limits the extent to which humans engage in corrective behavior and has been linked to loss of insight in a number of psychiatric syndromes (e.g., attention deficit hyperactivity disorder, drug a...
Article
Event-related potentials (ERPs) offer unparalleled temporal sensitivity in tracing the distinct electrocortical processing stages enabling cognition and are frequently utilized in clinical and experimental investigations, yet few studies have investigated their retest reliability. We administered a battery of typical ERP paradigms to elicit a diver...
Data
EEG drug effects for eyes open and eyes closed conditions. a) Delta eyes closed drug effect. b) Alpha1 eyes closed drug effect. c) Delta eyes closed drug by age interaction. d) Alpha1 eyes closed drug by session interaction. e) Alpha2 eyes open drug by region interaction. An asterisk next to the region name indicate a significant difference (p<0.05...
Data
CPAL performance for experiment 1 and experiment 2. Values are percent accuracy with values in brackets showing the standard error. (DOCX)
Data
Experiment 2 EEG results for drug effects on tonic EEG power and EEG reactivity. (DOCX)
Article
The adaptive gain theory highlights the pivotal role of the locus coeruleus-noradrenergic (LC-NE) system in regulating task engagement. In humans, however, LC-NE functional dynamics remain largely unknown. We evaluated the utility of two candidate psychophysiological markers of LC-NE activity: the P3 event-related potential and pupil diameter. Elec...