Genevieve Z Steiner | Western Sydney University (original) (raw)

Papers by Genevieve Z Steiner

This study aimed to evaluate the efficacy and safety of Ganoderma lucidum for the treatment of hy... more This study aimed to evaluate the efficacy and safety of Ganoderma lucidum for the treatment of hyperglycaemia and other cardiovascular risk components of metabolic syndrome using a prospective, double-blind, randomised, placebo-controlled trial. Eighty-four participants with type 2 diabetes mellitus and metabolic syndrome were randomised to one of three intervention groups: Ganoderma lucidum, Ganoderma lucidum with Cordyceps sinensis, or placebo. The dosage was 3 g/day of Ganoderma lucidum, with or without Cordyceps sinensis, for 16 weeks. The primary outcome measure was blood glucose (glycosylated haemoglobin [HbA1c] and fasting plasma glucose [FPG]); a number of secondary outcome measures were also tested. Data from the two intervention groups were combined. The combined intervention had no effect on any of the primary (baseline-adjusted difference in means: HbA1c = 0.13%, 95% CI [−0.35, 0.60], p = 0.60; FPG = 0.03 mmol/L, 95% CI [−0.90, 0.96], p = 0.95) or secondary outcome measures over the course of the 16-week trial, and no overall increased risk of adverse events with either active treatment. Evidence from this randomised clinical trial does not support the use of Ganoderma lucidum for treatment of cardiovascular risk factors in people with diabetes mellitus or metabolic syndrome. This Clinical Trial was registered with the Australian New Zealand Clinical Trials Registry on November 23, 2006. Trial ID: ACTRN12606000485538 and can be accessed here: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=81705. One of the leading causes of death worldwide is cardiovascular disease 1. This term most commonly refers to the chronic diseases caused by atherosclerosis, and most notably includes coronary heart disease and cerebrovascular disease. These conditions result in a significant burden on morbidity, quality of life, economic status and mortality for individuals and populations. Although the risk factors for cardiovascular disease are numerous and varied, the most important pharmacologically modifiable risk factors are high blood glucose, high blood pressure, an abnormal lipid profile, and obesity 1–5. The above risk factors are not independent of one another 6. It has been established that hyperglycaemia, hypertension, high triglycerides, low levels of high-density lipoprotein (HDL) cholesterol, and obesity have a complex metabolic relationship with insulin resistance, cardiovascular disease, and with each other 7 ; this combination of risk factors has been described as metabolic syndrome. Recognising this multifactorial nature of risk has had significant implications for the effective management of cardiovascular disease in individuals and populations. Modifiable risk factors, including those of metabolic syndrome, can be effectively treated with lifestyle modifications 2–4,8,9. Unfortunately, it is rare for these effects to be successfully sustained in the long term and consequently , pharmaceutical interventions are required for the majority of individuals. There is no single medication

P300 (or P3) is a major positive complex in the human event-related potential, occurring some 300... more P300 (or P3) is a major positive complex in the human event-related potential, occurring some 300 ms after stimulus onset, and long thought to be the cortical correlate of the Orienting Reflex, our automatic attention-grabbing response to a novel stimulus. The Novelty P3 was the third P3 subcomponent discovered (after P3a and P3b) and appeared promising in its sensitivity to stimulus novelty, the defining characteristic of the Orienting Reflex. But some 15 years later it was claimed to be indistinguishable from the previously-discovered P3a. This led to a decline in interest in the field and confused nomenclature, with some studies using " P3a " and " Novelty P3 " interchangeably. However, recent similar studies have again reported three subcomponents of the P3. Further, using single-stimulus habituation paradigms, in addition to P3a and P3b, a later decrementing P3 subcomponent has been reported, and recently labelled " HabP3 " to avoid contention. We report three studies to resolve this chaotic situation, arguing for identification of the late subcomponent following the P3a and P3b as the Novelty P3. Reinstatement of the Novelty P3 as the central index of the Orienting Reflex will have widespread impact in a range of theoretical, practical, and clinical areas involving novelty processing and attention. While the autonomic Orienting Reflex (OR) has provided a wealth of information in regard to our understanding of basic learning mechanisms, and fostered theory development, the search for a cortical correlate of this reflex has been long and difficult. It was proposed more than a quarter of a century ago that the P300 (or P3) event-related potential (ERP) component held the most promise as a cortical index of the OR 1. The P3 is a large centro-parietal deflection, peaking approximately 300 ms after stimulus onset, which increases as the degree of certainty concerning stimulus probability decreases 2. Initial reports emphasised the need for attention as a necessary condition for elicitation 2–5. However, evidence of a late positive wave to unpredictable but irrelevant stimuli 4,6 , differing in both latency and topographic distribution from that originally described 2 , suggested that the P3 represented a complex that differed with paradigm rather than being a single entity, leading to its label as the " late positive complex " (LPC) 7. An early (220–280 ms) fronto-central P3a elicited by both attended and non-attended deviant stimuli in an oddball task (with high probability standard stimuli and low probability " oddball " deviants) was then distinguished from a later (310–380 ms) parietal P3b that was enhanced for attended deviants 8. Squires and colleagues also reported a broadly-distributed late Slow Wave (SW) contemporaneous with the P3a and P3b peaks 8. A third P3 subcomponent, a later (360–450 ms) frontal Novelty P3 elicited by rare nontargets interspersed randomly in an attended oddball series (the " Novelty Oddball " paradigm) was also reported in the mid seventies 9. From our perspective, the Novelty P3 is of particular interest – it is the most likely cortical correlate of the OR, being uniquely associated with stimulus novelty, the OR's defining parameter. P3a, P3b, Novelty P3, and SW overlap and sum to form the LPC 10 , and a major problem is how to disentangle these. In recent years there has been an increase in the use of principal components analysis (PCA) for this purpose 10–15. This is a variety of factor analysis, and groups ERP activity into factors that correspond to ERP components , each reflecting topographically-similar time-locked activity. In an influential study, Simons et al. 13 replicated Squires et al.'s 8 paradigm and an auditory Novelty Oddball from Courchesne et al. 16. ERP averages for the 220–420 ms epoch from each of the two data sets (N = 9 each) were combined in a PCA using the covariance matrix; further details were not provided. Four factors were extracted from each set. Exploration of the two factor structures showed that the distributions of what were identified as the P3a factor scores and the Novelty P3 factor scores were statistically indistinguishable, leading the authors to assert that " the arguments originally marshalled in support of the distinction between the Novelty P3 and the P3a have not been empirically supported " 13. This has become the dominant perspective in the literature 17,18 .

International Journal of Psychophysiology, Sep 2013

Psychophysiology, 2014

We aimed to clarify sequential processes for cue and imperative stimuli (targets/nontargets) in a... more We aimed to clarify sequential processes for cue and imperative stimuli (targets/nontargets) in a continuous performance test (CPT), and how the preparatory contingent negative variation (CNV) affects physiological and behavioral responses. Single-trial event-related potentials (ERPs) obtained from 70 participants during a cued CPT were baselined to the cue (BtC) to include the CNV, or to the imperatives (BtI) to remove the CNV. Principal components analysis obtained cue and imperative ERP components, and congruence coefficients (rc ) evaluated similarities. The cue and imperative components were comparable, more so for the BtI- than BtC-imperative components (rc = .85). N1, PN, P2, N2c, and SW components were similar, but not the N2b and P3s. Imperative ERPs were largely unaffected by the resolving CNV. Similar cue and imperative components suggest similar sequential processes, while preparatory CNV activity enhanced physiological and behavioral responses.

In oddball tasks, the P3 component of the event-related potential systematically varies with the ... more In oddball tasks, the P3 component of the event-related potential systematically varies with the time between target stimuli—the target-to-target interval (TTI). Longer TTIs result in larger P3 amplitudes and shorter latencies, and this pattern of results has been linked with working memory-updating processes. Given that working memory and the P3 have both been shown to diminish with age, the current study aimed to determine whether the linear relationship between P3 and TTI is compromised in healthy aging by comparing TTI effects on P3 amplitudes and latencies, and reaction time (RT), in young and older adults. Older adults were found to have an overall reduction in P3 amplitudes, longer latencies, an anterior shift in topography, a trend toward slower RTs, and a flatter linear relationship between P3 and TTI than young adults. Results suggest that the ability to maintain templates in working memory required for stimulus categorization decreases with age, and that as a result, neural compensatory mechanisms are employed.

Background: Sailuotong (SLT) is a standardised herbal medicine formula consisting of Panax ginsen... more Background: Sailuotong (SLT) is a standardised herbal medicine formula consisting of Panax ginseng, Ginkgo biloba,
and Crocus sativus, and has been designed to enhance cognitive and cardiovascular function.
Methods: Using a randomised, double-blind, placebo controlled crossover design, this pilot study assessed the
effect of treatment for 1 week with SLT and placebo (1 week washout period) on neurocognitive and cardiovascular
function in healthy adults. Sixteen adults completed a computerised neuropsychological test battery (Compass), and
had their electroencephalographic (EEG) activity and cardiovascular system function assessed. Primary outcome
measures were cognitive test scores and oddball task event-related potential (ERP) component amplitudes.
Secondary outcome measures were resting EEG spectral band amplitudes, and cardiovascular parameters.
Results: Treatment with SLT, compared to placebo, resulted in small improvements in working memory, a slight
increase in auditory target (cf. nontarget) P3a amplitude, and a decrease in auditory N1 target (cf. nontarget)
amplitude. There was no effect of SLT on EEG amplitude in delta, theta, alpha, or beta bands in both eyes open
and eyes closed resting conditions, or on aortic and peripheral pulse pressure, and resting heartrate.
Conclusions: Findings suggest that SLT has the potential to improve working memory performance in healthy
adults; a larger sample size is needed to confirm this.

International Journal of Psychophysiology, 2014

presented at the 17th World Congress of Psychophysiology (IOP2014) of the International Organizat... more presented at the 17th World Congress of Psychophysiology (IOP2014) of the International Organization of Psychophysiology (IOP) Hiroshima, Japan, September 23rd to 27th, 2014

Psychophysiology

This study examined temporal determinants of the P300 component of the ERP in a three-stimulus vi... more This study examined temporal determinants of the P300 component of the ERP in a three-stimulus visual oddball task. Frequent standards, with equiprobable targets and infrequent nontargets, were utilized. We tested whether the infrequent nontarget-to-nontarget interval (infrequent NNI) influences P300 amplitudes and latencies analogously to the target-to-target interval (TTI). EEG was recorded from 27 participants, and response time and P300 effects of TTIs and infrequent NNIs were assessed. Increases in TTI augmented target P300 amplitudes and decreased latencies and response times. However, this modulation of P300 amplitude was weak for manipulations of infrequent NNI. P300 latencies increased initially before decreasing across infrequent NNI levels. Together, these findings support the notion that the P300 has an underlying temporal mechanism that is modulated by motivationally significant events. Theoretical implications are discussed.

Psychophysiology, Jan 1, 2011

This study examined skin conductance responses, the late positive complex of the event-related po... more This study examined skin conductance responses, the late positive complex of the event-related potential, and pupillary dilation responses as autonomic and central correlates of the orienting reflex (OR) in the context of indifferent and significant stimuli. In particular, we aimed to clarify the inconsistencies surrounding the pupillary dilation response as an OR index. An auditory dishabituation paradigm was employed, and physiological measures were recorded from 24 participants. Response decrement to a repeated stimulus, response recovery to a change stimulus, and subsequent dishabituation were assessed. Findings confirmed expectations that the skin conductance response and the late positive complex are indices of the OR. The pupillary dilation response, however, demonstrated an unexpected sensitivity to stimulus novelty only, while the prestimulus measure of tonic pupil diameter showed the significance effect that was expected of the phasic measure. Together, these findings argue against the suggestion that the pupillary dilation response is an OR index. The diverse results obtained from this experiment contribute to our understanding of the OR, and provide impetus for further research with a variety of paradigm manipulations.

Neurophysiology of Learning and Memory, Jan 1, 2011

In this study we explored elicitation and habituation of the orienting reflex (OR) in the context... more In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2–4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5–7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently; order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus; both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation; this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.► Phasic and tonic electrodermal activity demonstrated significance effects. ► Pre-stimulus arousal determined phasic response amplitude. ► Sensitisation did not determine dishabituation for indifferent stimuli.

Psychophysiology

Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure... more Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure of the Orienting Reflex (OR). Early studies confirmed that this reduced with repeated auditory stimulation, but without reliable stimulus-significance effects. We presented an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time–frequency analysis of electrooculogram (EOG)-corrected EEG was used to explore prestimulus levels and the timing and amplitude of event-related increases and decreases in 4 classic EEG bands. Decrement over trials and response recovery were substantial for the transient increase (in delta, theta, and alpha) and subsequent desynchronization (in theta, alpha, and beta). There was little evidence of dishabituation and few effects of counting. Expected effects in stimulus-induced alpha desynchronization were confirmed. Two EEG response patterns over trials and conditions, distinct from the full OR pattern, warrant further research.

International Journal of Psychophysiology

This study examined autonomic measures and event-related potentials (ERPs) associated with elicit... more This study examined autonomic measures and event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Subjects received 16 innocuous tones with intensity alternating between 60 and 80 dB, at long inter-stimulus intervals. There was no stimulus-related task, so we could examine the effects of stimulus novelty and intensity in the absence of task demands. Cardiac, respiratory, peripheral vasoconstriction, and electrodermal measures were recorded, as well as continuous EEG. Single-trial ERPs were obtained, and components extracted by Principal Components Analysis were examined for potential response fractionation in the central indices of stimulus processing. The predicted fractionation of autonomic measures was obtained: cardiac deceleration showed no systematic change with intensity or trials, respiratory pause showed a substantial main effect of trials but no intensity effects, peripheral vasoconstriction showed intensity but no trials effects, and electrodermal responses showed substantial main effects of trials and intensity. A range of intensity and novelty effects were obtained in components identified as the N1, P3a, P3b, Novelty P3, and the classic Slow Wave. The different stimulus–response profiles of the ERP components are discussed in relation to the autonomic response profiles within the context of a sequential processing theory of OR elicitation.► We examined trials and intensity effects in relation to the Orienting Reflex. ► Cardiovascular, respiratory, and electrodermal responses showed different profiles. ► PCA-derived components from single-trial ERPs also showed response fractionation. ► Autonomic and central results are related to Preliminary Process Theory of the OR.

This study aimed to evaluate the efficacy and safety of Ganoderma lucidum for the treatment of hy... more This study aimed to evaluate the efficacy and safety of Ganoderma lucidum for the treatment of hyperglycaemia and other cardiovascular risk components of metabolic syndrome using a prospective, double-blind, randomised, placebo-controlled trial. Eighty-four participants with type 2 diabetes mellitus and metabolic syndrome were randomised to one of three intervention groups: Ganoderma lucidum, Ganoderma lucidum with Cordyceps sinensis, or placebo. The dosage was 3 g/day of Ganoderma lucidum, with or without Cordyceps sinensis, for 16 weeks. The primary outcome measure was blood glucose (glycosylated haemoglobin [HbA1c] and fasting plasma glucose [FPG]); a number of secondary outcome measures were also tested. Data from the two intervention groups were combined. The combined intervention had no effect on any of the primary (baseline-adjusted difference in means: HbA1c = 0.13%, 95% CI [−0.35, 0.60], p = 0.60; FPG = 0.03 mmol/L, 95% CI [−0.90, 0.96], p = 0.95) or secondary outcome measures over the course of the 16-week trial, and no overall increased risk of adverse events with either active treatment. Evidence from this randomised clinical trial does not support the use of Ganoderma lucidum for treatment of cardiovascular risk factors in people with diabetes mellitus or metabolic syndrome. This Clinical Trial was registered with the Australian New Zealand Clinical Trials Registry on November 23, 2006. Trial ID: ACTRN12606000485538 and can be accessed here: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=81705. One of the leading causes of death worldwide is cardiovascular disease 1. This term most commonly refers to the chronic diseases caused by atherosclerosis, and most notably includes coronary heart disease and cerebrovascular disease. These conditions result in a significant burden on morbidity, quality of life, economic status and mortality for individuals and populations. Although the risk factors for cardiovascular disease are numerous and varied, the most important pharmacologically modifiable risk factors are high blood glucose, high blood pressure, an abnormal lipid profile, and obesity 1–5. The above risk factors are not independent of one another 6. It has been established that hyperglycaemia, hypertension, high triglycerides, low levels of high-density lipoprotein (HDL) cholesterol, and obesity have a complex metabolic relationship with insulin resistance, cardiovascular disease, and with each other 7 ; this combination of risk factors has been described as metabolic syndrome. Recognising this multifactorial nature of risk has had significant implications for the effective management of cardiovascular disease in individuals and populations. Modifiable risk factors, including those of metabolic syndrome, can be effectively treated with lifestyle modifications 2–4,8,9. Unfortunately, it is rare for these effects to be successfully sustained in the long term and consequently , pharmaceutical interventions are required for the majority of individuals. There is no single medication

P300 (or P3) is a major positive complex in the human event-related potential, occurring some 300... more P300 (or P3) is a major positive complex in the human event-related potential, occurring some 300 ms after stimulus onset, and long thought to be the cortical correlate of the Orienting Reflex, our automatic attention-grabbing response to a novel stimulus. The Novelty P3 was the third P3 subcomponent discovered (after P3a and P3b) and appeared promising in its sensitivity to stimulus novelty, the defining characteristic of the Orienting Reflex. But some 15 years later it was claimed to be indistinguishable from the previously-discovered P3a. This led to a decline in interest in the field and confused nomenclature, with some studies using " P3a " and " Novelty P3 " interchangeably. However, recent similar studies have again reported three subcomponents of the P3. Further, using single-stimulus habituation paradigms, in addition to P3a and P3b, a later decrementing P3 subcomponent has been reported, and recently labelled " HabP3 " to avoid contention. We report three studies to resolve this chaotic situation, arguing for identification of the late subcomponent following the P3a and P3b as the Novelty P3. Reinstatement of the Novelty P3 as the central index of the Orienting Reflex will have widespread impact in a range of theoretical, practical, and clinical areas involving novelty processing and attention. While the autonomic Orienting Reflex (OR) has provided a wealth of information in regard to our understanding of basic learning mechanisms, and fostered theory development, the search for a cortical correlate of this reflex has been long and difficult. It was proposed more than a quarter of a century ago that the P300 (or P3) event-related potential (ERP) component held the most promise as a cortical index of the OR 1. The P3 is a large centro-parietal deflection, peaking approximately 300 ms after stimulus onset, which increases as the degree of certainty concerning stimulus probability decreases 2. Initial reports emphasised the need for attention as a necessary condition for elicitation 2–5. However, evidence of a late positive wave to unpredictable but irrelevant stimuli 4,6 , differing in both latency and topographic distribution from that originally described 2 , suggested that the P3 represented a complex that differed with paradigm rather than being a single entity, leading to its label as the " late positive complex " (LPC) 7. An early (220–280 ms) fronto-central P3a elicited by both attended and non-attended deviant stimuli in an oddball task (with high probability standard stimuli and low probability " oddball " deviants) was then distinguished from a later (310–380 ms) parietal P3b that was enhanced for attended deviants 8. Squires and colleagues also reported a broadly-distributed late Slow Wave (SW) contemporaneous with the P3a and P3b peaks 8. A third P3 subcomponent, a later (360–450 ms) frontal Novelty P3 elicited by rare nontargets interspersed randomly in an attended oddball series (the " Novelty Oddball " paradigm) was also reported in the mid seventies 9. From our perspective, the Novelty P3 is of particular interest – it is the most likely cortical correlate of the OR, being uniquely associated with stimulus novelty, the OR's defining parameter. P3a, P3b, Novelty P3, and SW overlap and sum to form the LPC 10 , and a major problem is how to disentangle these. In recent years there has been an increase in the use of principal components analysis (PCA) for this purpose 10–15. This is a variety of factor analysis, and groups ERP activity into factors that correspond to ERP components , each reflecting topographically-similar time-locked activity. In an influential study, Simons et al. 13 replicated Squires et al.'s 8 paradigm and an auditory Novelty Oddball from Courchesne et al. 16. ERP averages for the 220–420 ms epoch from each of the two data sets (N = 9 each) were combined in a PCA using the covariance matrix; further details were not provided. Four factors were extracted from each set. Exploration of the two factor structures showed that the distributions of what were identified as the P3a factor scores and the Novelty P3 factor scores were statistically indistinguishable, leading the authors to assert that " the arguments originally marshalled in support of the distinction between the Novelty P3 and the P3a have not been empirically supported " 13. This has become the dominant perspective in the literature 17,18 .

International Journal of Psychophysiology, Sep 2013

Psychophysiology, 2014

We aimed to clarify sequential processes for cue and imperative stimuli (targets/nontargets) in a... more We aimed to clarify sequential processes for cue and imperative stimuli (targets/nontargets) in a continuous performance test (CPT), and how the preparatory contingent negative variation (CNV) affects physiological and behavioral responses. Single-trial event-related potentials (ERPs) obtained from 70 participants during a cued CPT were baselined to the cue (BtC) to include the CNV, or to the imperatives (BtI) to remove the CNV. Principal components analysis obtained cue and imperative ERP components, and congruence coefficients (rc ) evaluated similarities. The cue and imperative components were comparable, more so for the BtI- than BtC-imperative components (rc = .85). N1, PN, P2, N2c, and SW components were similar, but not the N2b and P3s. Imperative ERPs were largely unaffected by the resolving CNV. Similar cue and imperative components suggest similar sequential processes, while preparatory CNV activity enhanced physiological and behavioral responses.

In oddball tasks, the P3 component of the event-related potential systematically varies with the ... more In oddball tasks, the P3 component of the event-related potential systematically varies with the time between target stimuli—the target-to-target interval (TTI). Longer TTIs result in larger P3 amplitudes and shorter latencies, and this pattern of results has been linked with working memory-updating processes. Given that working memory and the P3 have both been shown to diminish with age, the current study aimed to determine whether the linear relationship between P3 and TTI is compromised in healthy aging by comparing TTI effects on P3 amplitudes and latencies, and reaction time (RT), in young and older adults. Older adults were found to have an overall reduction in P3 amplitudes, longer latencies, an anterior shift in topography, a trend toward slower RTs, and a flatter linear relationship between P3 and TTI than young adults. Results suggest that the ability to maintain templates in working memory required for stimulus categorization decreases with age, and that as a result, neural compensatory mechanisms are employed.

Background: Sailuotong (SLT) is a standardised herbal medicine formula consisting of Panax ginsen... more Background: Sailuotong (SLT) is a standardised herbal medicine formula consisting of Panax ginseng, Ginkgo biloba,
and Crocus sativus, and has been designed to enhance cognitive and cardiovascular function.
Methods: Using a randomised, double-blind, placebo controlled crossover design, this pilot study assessed the
effect of treatment for 1 week with SLT and placebo (1 week washout period) on neurocognitive and cardiovascular
function in healthy adults. Sixteen adults completed a computerised neuropsychological test battery (Compass), and
had their electroencephalographic (EEG) activity and cardiovascular system function assessed. Primary outcome
measures were cognitive test scores and oddball task event-related potential (ERP) component amplitudes.
Secondary outcome measures were resting EEG spectral band amplitudes, and cardiovascular parameters.
Results: Treatment with SLT, compared to placebo, resulted in small improvements in working memory, a slight
increase in auditory target (cf. nontarget) P3a amplitude, and a decrease in auditory N1 target (cf. nontarget)
amplitude. There was no effect of SLT on EEG amplitude in delta, theta, alpha, or beta bands in both eyes open
and eyes closed resting conditions, or on aortic and peripheral pulse pressure, and resting heartrate.
Conclusions: Findings suggest that SLT has the potential to improve working memory performance in healthy
adults; a larger sample size is needed to confirm this.

International Journal of Psychophysiology, 2014

presented at the 17th World Congress of Psychophysiology (IOP2014) of the International Organizat... more presented at the 17th World Congress of Psychophysiology (IOP2014) of the International Organization of Psychophysiology (IOP) Hiroshima, Japan, September 23rd to 27th, 2014

Psychophysiology

This study examined temporal determinants of the P300 component of the ERP in a three-stimulus vi... more This study examined temporal determinants of the P300 component of the ERP in a three-stimulus visual oddball task. Frequent standards, with equiprobable targets and infrequent nontargets, were utilized. We tested whether the infrequent nontarget-to-nontarget interval (infrequent NNI) influences P300 amplitudes and latencies analogously to the target-to-target interval (TTI). EEG was recorded from 27 participants, and response time and P300 effects of TTIs and infrequent NNIs were assessed. Increases in TTI augmented target P300 amplitudes and decreased latencies and response times. However, this modulation of P300 amplitude was weak for manipulations of infrequent NNI. P300 latencies increased initially before decreasing across infrequent NNI levels. Together, these findings support the notion that the P300 has an underlying temporal mechanism that is modulated by motivationally significant events. Theoretical implications are discussed.

Psychophysiology, Jan 1, 2011

This study examined skin conductance responses, the late positive complex of the event-related po... more This study examined skin conductance responses, the late positive complex of the event-related potential, and pupillary dilation responses as autonomic and central correlates of the orienting reflex (OR) in the context of indifferent and significant stimuli. In particular, we aimed to clarify the inconsistencies surrounding the pupillary dilation response as an OR index. An auditory dishabituation paradigm was employed, and physiological measures were recorded from 24 participants. Response decrement to a repeated stimulus, response recovery to a change stimulus, and subsequent dishabituation were assessed. Findings confirmed expectations that the skin conductance response and the late positive complex are indices of the OR. The pupillary dilation response, however, demonstrated an unexpected sensitivity to stimulus novelty only, while the prestimulus measure of tonic pupil diameter showed the significance effect that was expected of the phasic measure. Together, these findings argue against the suggestion that the pupillary dilation response is an OR index. The diverse results obtained from this experiment contribute to our understanding of the OR, and provide impetus for further research with a variety of paradigm manipulations.

Neurophysiology of Learning and Memory, Jan 1, 2011

In this study we explored elicitation and habituation of the orienting reflex (OR) in the context... more In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2–4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5–7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently; order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus; both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation; this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.► Phasic and tonic electrodermal activity demonstrated significance effects. ► Pre-stimulus arousal determined phasic response amplitude. ► Sensitisation did not determine dishabituation for indifferent stimuli.

Psychophysiology

Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure... more Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure of the Orienting Reflex (OR). Early studies confirmed that this reduced with repeated auditory stimulation, but without reliable stimulus-significance effects. We presented an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time–frequency analysis of electrooculogram (EOG)-corrected EEG was used to explore prestimulus levels and the timing and amplitude of event-related increases and decreases in 4 classic EEG bands. Decrement over trials and response recovery were substantial for the transient increase (in delta, theta, and alpha) and subsequent desynchronization (in theta, alpha, and beta). There was little evidence of dishabituation and few effects of counting. Expected effects in stimulus-induced alpha desynchronization were confirmed. Two EEG response patterns over trials and conditions, distinct from the full OR pattern, warrant further research.

International Journal of Psychophysiology

This study examined autonomic measures and event-related potentials (ERPs) associated with elicit... more This study examined autonomic measures and event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Subjects received 16 innocuous tones with intensity alternating between 60 and 80 dB, at long inter-stimulus intervals. There was no stimulus-related task, so we could examine the effects of stimulus novelty and intensity in the absence of task demands. Cardiac, respiratory, peripheral vasoconstriction, and electrodermal measures were recorded, as well as continuous EEG. Single-trial ERPs were obtained, and components extracted by Principal Components Analysis were examined for potential response fractionation in the central indices of stimulus processing. The predicted fractionation of autonomic measures was obtained: cardiac deceleration showed no systematic change with intensity or trials, respiratory pause showed a substantial main effect of trials but no intensity effects, peripheral vasoconstriction showed intensity but no trials effects, and electrodermal responses showed substantial main effects of trials and intensity. A range of intensity and novelty effects were obtained in components identified as the N1, P3a, P3b, Novelty P3, and the classic Slow Wave. The different stimulus–response profiles of the ERP components are discussed in relation to the autonomic response profiles within the context of a sequential processing theory of OR elicitation.► We examined trials and intensity effects in relation to the Orienting Reflex. ► Cardiovascular, respiratory, and electrodermal responses showed different profiles. ► PCA-derived components from single-trial ERPs also showed response fractionation. ► Autonomic and central results are related to Preliminary Process Theory of the OR.