Improving access to public physical activity events for disadvantaged communities in Australia.

BACKGROUND: Physical activity has numerous health benefits, but participation is lower in disadvantaged communities. 'parkrun' overcomes one of the main barriers for disadvantaged communities, the cost of activities, by providing a free, regular community-based physical activity event for walkers, runners and volunteers. This study assesses equity of access (in terms of distance to the nearest parkrun) stratified by socioeconomic deprivation, and identifies the optimal location for 100 new events to increase equity of access. METHODS: We combined information about population location and socioeconomic deprivation, with information about the location of 403 existing parkrun events, to assess the current level of access by deprivation quintile. We then used a two-step location-allocation analysis (minimising the sum of deprivation-weighted distances) to identify optimal regions, then optimal towns within those regions, as the ideal locations for 100 new parkrun events. RESULTS: Currently, 63.1% of the Australian population lives within 5 km of an event, and the average distance to an event is 14.5 km. A socioeconomic gradient exists, with the most deprived communities having the largest average distance to an event (27.0 km), and the least deprived communities having the best access (living an average 6.6 km from an event). Access improves considerably after the introduction of new event locations with around 68% of the population residing within 5 km of an event, and the average distance to the nearest event approximately 8 km. Most importantly, the improvement in access will be greatest for the most deprived communities (now an average 11 km from an event). CONCLUSIONS: There is a socioeconomic gradient in access to parkrun events. Strategic selection of new parkrun locations will improve equity of access to community physical activity events, and could contribute to enabling greater participation in physical activity by disadvantaged communities.

Can Inhibitory Training Produce Reductions in Drinking? Evaluating the Influence of the Control Condition.

OBJECTIVE: Training in an inhibitory control task has produced reductions in alcohol use among heavy drinkers. However, the longevity of effects remains unknown, and much research has used suboptimal control conditions. Here, we assess the effectiveness of "Beer-NoGo" inhibitory training to reduce consumption up to 4 weeks after training compared with a "Beer-Go" control task, an online version of the Brief Alcohol Intervention (BAI), and an Oddball control condition. METHOD: Eighty-one regular drinkers were randomized into one of four training conditions. In the Beer-NoGo condition, participants responded to a letter superimposed on water-related images and refrained from responding to another letter superimposed on beer-related images. The mapping was reversed for the Beer-Go condition, whereas the Oddball control condition was presented with letters only and inhibition was not required. The last condition was an online BAI. Alcohol use was assessed using a bogus taste test and weekly alcohol consumption. RESULTS: Taste-test consumption was greater in the Beer-Go condition than in the Beer-NoGo, which did not differ from the Oddball and BAI conditions. All groups reduced alcohol intake during the study; however, in the first week the Beer-Go group reduced their drinking while the Beer-NoGo group increased. No group differences were apparent at the fourth week. CONCLUSIONS: The Beer-NoGo task did not produce effects beyond simple assessment on reducing alcohol use among regular drinkers. Previously reported training effects may be artifacts of the Beer-Go task as a suboptimal control. More robust forms of inhibitory training are necessary if a useful clinical adjunct for managing alcohol abuse is to be developed.

Verbal Learning and Memory in Cannabis and Alcohol Users: An Event-Related Potential Investigation.

Aims: Long-term heavy use of cannabis and alcohol are known to be associated with memory impairments. In this study, we used event-related potentials to examine verbal learning and memory processing in a commonly used behavioral task. Method: We conducted two studies: first, a small pilot study of adolescent males, comprising 13 Drug-Naive Controls (DNC), 12 heavy drinkers (HD) and 8 cannabis users (CU). Second, a larger study of young adults, comprising 45 DNC (20 female), 39 HD (16 female), and 20 CU (9 female). In both studies, participants completed a modified verbal learning task (the Rey Auditory Verbal Learning Test, RAVLT) while brain electrical activity was recorded. ERPs were calculated for words which were subsequently remembered vs. those which were not remembered, and for presentations of learnt words, previously seen words, and new words in a subsequent recognition test. Pre-planned principal components analyses (PCA) were used to quantify the ERP components in these recall and recognition phases separately for each study. Results: Memory performance overall was slightly lower than published norms using the standardized RAVLT delivery, but was generally similar and showed the expected changes over trials. Few differences in performance were observed between groups; a notable exception was markedly poorer delayed recall in HD relative to DNC (Study 2). PCA identified components expected from prior research using other memory tasks. At encoding, there were no between-group differences in the usual P2 recall effect (larger for recalled than not-recalled words). However, alcohol-related differences were observed in a larger P540 (indexing recollection) in HD than DNC, and cannabis-related differences were observed in a smaller N340 (indexing familiarity) and a lack of previously seen > new words effect for P540 in Study 2. Conclusions: This study is the first examination of ERPs in the RAVLT in healthy control participants, as well as substance-using individuals, and represents an important advance in methodology. The results indicate alterations in recognition memory processing, which even if not manifesting in overt behavioral impairment, underline the potential for brain dysfunction with early exposure to alcohol and cannabis.

Current forms of inhibitory training produce no greater reduction in drinking than simple assessment: A preliminary study.

BACKGROUND: Disinhibition is apparent in users of many substances, including heavy drinkers. Previous research has shown that brief training to improve inhibitory control is associated with reduced alcohol consumption. We investigated whether a new form of inhibitory training would produce greater reductions, relative to a carefully designed control condition and a proven method of reducing consumption, the Brief Alcohol Intervention (BAI). METHODS: One hundred and fourteen regular drinkers were assigned randomly to one of five training conditions: Control (no inhibitory training); Beer-NoGo (inhibit responses linked to task-irrelevant pictures of beer); Restrained-Stop (requiring more urgent inhibition but without pictures of beer); Combined (a previously untested form of training requiring urgent inhibition to pictures of beer); or BAI. The outcome measures were alcohol consumption in the week before and after training, and in a bogus taste test administered immediately post-training. RESULTS: Participation in the study, regardless of condition, was associated with reductions in weekly consumption. However, only the BAI produced a greater reduction relative to the Control condition. The training tasks were not associated with reductions in taste test consumption. CONCLUSIONS: Although concerns about low power limit confidence, the current study suggests that three forms of inhibitory training do not have a substantial effect on drinking beyond the effect of simple assessment, in comparison to a control task which does not promote impulsive responding. Future research needs to establish a training protocol that produces greater reductions in consumption not only relative to the effect of assessment but also relative to a BAI.

Error detection and behavioural inhibition in young heavy drinkers.

BACKGROUND: Increases in inhibitory errors in heavy drinkers are established; less well-studied is whether heavy drinkers are aware of these errors in performance. Reductions in error detection and awareness limit the possibility for remedial action to be taken, and have implications for substance abusers seeking to control use: failure to monitor and/or adjust ongoing behaviour may be linked to using more or more often than intended, and failing to adjust behaviour after a slip. Here we report the first study of both inhibitory control and error awareness in young heavy drinkers, using behavioural and psychophysiological measures. METHODS: Heavy drinkers (n=25) and light- or non-drinking controls (n=35) completed a difficult inhibitory task which required signaling the awareness of inhibitory errors on the subsequent trial, while brain electrical activity was recorded. RESULTS: Heavy drinkers made more inhibitory errors than controls, but we observed no difference in error awareness, both via overt signaling and with equivalent amplitude of the error positivity (Pe), indexing conscious error detection. Similarly, controls and heavy drinkers showed no difference in amplitude or latency of the error-related negativity (ERN), indexing early pre-conscious error detection. CONCLUSIONS: This research suggests no significant difference in detection of errors in heavy drinkers, even as they are more prone to make these errors, a result seen in dependent drinkers reported elsewhere. Future research with larger sample sizes, and a more difficult task producing sufficient errors, should determine whether heavy drinkers employ sufficient post-error remedial action.

Feedforward consequences of isometric contractions: effort and ventilation.

The onset of voluntary muscle contractions causes rapid increases in ventilation and is accompanied by a sensation of effort. Both the ventilatory response and perception of effort are proportional to contraction intensity, but these behaviors have been generalized from contractions of a single muscle group. Our aim was to determine how these relationships are affected by simultaneous contractions of multiple muscle groups. We examined the ventilatory response and perceived effort of contraction during separate and simultaneous isometric contractions of the contralateral elbow flexors and of an ipsilateral elbow flexor and knee extensor. Subjects made 10-sec contractions at 25, 50, and 100% of maximum during normocapnia and hypercapnia. For simultaneous contractions, both muscle groups were activated at the same intensities. Ventilation was measured continuously and subjects rated the effort required to produce each contraction. As expected, ventilation and perceived effort increased proportionally with contraction intensity during individual contractions. However, during simultaneous contractions, neither ventilation nor effort reflected the combined muscle output. Rather, the ventilatory response was similar to when contractions were performed separately, and effort ratings showed a small but significant increase for simultaneous contractions. Hypercapnia at rest doubled baseline ventilation, but did not affect the difference in perceived effort between separate and simultaneous contractions. The ventilatory response and the sense of effort at the onset of muscle activity are not related to the total output of the motor pathways, or the working muscles, but arise from cortical regions upstream from the motor cortex.

Sex differences in the relationship between heavy alcohol use, inhibition and performance monitoring: Disconnect between behavioural and brain functional measures.

Previous research has reported mixed evidence of sex differences in the relationship between heavy alcohol use and deficits in behavioural control. Here, we examine sex differences in behavioural and event-related potential (ERP) markers of deficient inhibition. Participants were 71 young adults aged 18-21, who either drank heavily regularly (i.e., four standard drinks on one occasion, at least once a month, n=33, 20 male) or drank heavily less often than this (including never, n=38, 21 male). They completed a stop-signal task while ERPs were recorded. Increases in stop-signal reaction time, the time required to stop a response, were related to heavy drinking only in female participants. P3 amplitude, ERN amplitude and ERN latency did not display a significant interaction between group and sex. Heavy drinkers, regardless of sex, displayed a marginally larger successful>failed effect for P3 amplitude, and a marginally smaller error-related negativity. An apparent disconnect exists in behavioural and psychophysiological measures of sex differences in the relationship between heavy alcohol consumption and inhibitory processing; male heavy drinkers display only psychophysiological but not behavioural deficits, while female heavy drinkers display both. Future research may determine whether sex differences are apparent for other substances besides alcohol.

Female but not male young heavy drinkers display altered performance monitoring.

Difficulties in monitoring ongoing behaviour may be linked to real-life problematic drinking behaviours. Prior research suggests female heavy drinkers in particular display greater cognitive control deficits. Here, we examine trial-to-trial behavioural adaptations in a conflict monitoring task, relative to drinking behaviour and sex. Heavy drinkers (n=31, 16 male) and controls (n=35, 18 male) completed an Eriksen flanker task while brain electrical activity was recorded. For reaction time, error rates, and N2 and P3 amplitude of the event-related potential, trial-to-trial conflict adaptation was evidenced by a differential response to the current (congruent vs. incongruent) trials dependent on the identity of the previous trial. For the proportion of errors, heavy drinkers showed increased conflict adaptation compared to controls. Conflict adaptation for N2 (indexing monitoring) was larger for female heavy drinkers than controls, and the opposite was observed for males. There were no interactions involving group or sex for the P3 (indexing inhibition). The results suggest a compensatory response, such that heavy drinkers are required to increase performance monitoring in order to achieve the same behavioural outcome as controls. We also confirm the importance of sex as a factor in the relationship between behavioural control and heavy alcohol use.

Deficits in behavioural inhibition in substance abuse and addiction: a meta-analysis.

AIMS: Deficits in behavioural inhibitory control are attracting increasing attention as a factor behind the development and maintenance of substance dependence. However, evidence for such a deficit is varied in the literature. Here, we synthesised published results to determine whether inhibitory ability is reliably impaired in substance users compared to controls. METHODS: The meta-analysis used fixed-effects models to integrate results from 97 studies that compared groups with heavy substance use or addiction-like behaviours with healthy control participants on two experimental paradigms commonly used to assess response inhibition: the Go/NoGo task, and the Stop-Signal Task (SST). The primary measures of interest were commission errors to NoGo stimuli and stop-signal reaction time in the SST. Additionally, we examined omission errors to Go stimuli, and reaction time in both tasks. Because inhibition is more difficult when inhibition is required infrequently, we considered papers with rare and equiprobable NoGo stimuli separately. RESULTS: Inhibitory deficits were apparent for heavy use/dependence on cocaine, MDMA, methamphetamine, tobacco, and alcohol (and, to a lesser extent, non-dependent heavy drinkers), and in pathological gamblers. On the other hand, no evidence for an inhibitory deficit was observed for opioids or cannabis, and contradictory evidence was observed for internet addiction. CONCLUSIONS: The results are generally consistent with the view that substance use disorders and addiction-like behavioural disorders are associated with impairments in inhibitory control. Implications for treatment of substance use are discussed, along with suggestions for future research arising from the limitations of the extant literature.

Evidence of deficits in behavioural inhibition and performance monitoring in young female heavy drinkers.

BACKGROUND: New models of the development and maintenance of substance abuse give increasing importance to the role of deficits in inhibitory function. Much of the evidence to support this claim comes from male participants, despite some researchers showing greater disinhibition in females. Clearly, more research on female heavy drinkers is warranted. In this study, we examine behavioural and psychophysiological measures of inhibitory function in female young adults who do and do not regularly drink heavily. METHODS: Participants were thirty female young adults (aged 18-21) who drink heavily (four or more standard drinks per occasion) at least once a month (n=13) or who drink heavily less often than this (n=17); none regularly used any other drugs, including tobacco. They underwent interviews assessing prior use of alcohol, before completing a stop-signal task while brain electrical activity was recorded. RESULTS: Regular heavy drinkers displayed a longer stop-signal reaction time (the time required to stop an inappropriate response), and a larger P3 increase for successful compared to failed inhibition trials. Heavy drinkers also displayed a smaller error-related negativity (ERN) amplitude, indexing a deficit in performance monitoring. CONCLUSION: These results indicate that large deficits in inhibitory processing and performance monitoring occur in young female heavy drinkers, and that heavy drinkers may have to work harder in order to successfully inhibit a response. Future research may determine whether these deficits pre-date or are caused by alcohol abuse.

CNV resolution does not cause NoGo anteriorisation of the P3: a failure to replicate Simson et al.

For 35 years, some researchers have argued that CNV resolution may affect or even produce the increased P3 for NoGo compared to Go trials, and thus that no 'inhibitory' NoGo P3 exists. This is based on the work of Simson et al. (1977b), the scalp topography of potentials in auditory and visual Go/NoGo tasks. Electroencephalography and Clinical Neurophysiology, 43, 864-875, which compared Go and NoGo topography after CNV was subtracted from NoGo trials only. Specifically, the NoGo P3 topography showed the distinctive frontocentral maximum, which is often linked to motor inhibition, when referenced to a pre-target baseline. This NoGo topography changed to a more parietal maximum, similar to that on Go trials, when referenced to a pre-cue baseline. Many researchers have cited this study, while failing to use the delayed response design on which Simson et al. based their argument. We attempted to replicate Simson et al.'s experiment with delayed responses and also with immediate responses, as are more often used. As expected, the amplitudes of CNV and P3 to both Go and NoGo trials were increased when immediate compared to delayed responses were required, but we failed to replicate the topographic shift of NoGo P3 with different baselines for both delayed and immediate responses. That is, subtraction of the CNV from NoGo P3 did not change the distinctive frontocentral topography of this component. The results suggest that CNV may affect the amplitude and measurement of the NoGo P3, but that NoGo P3 anteriorisation is not caused by CNV resolution.

Parafac and go/no-go: disentangling CNV return from the P3 complex by trilinear component analysis.

It has been proposed that the fronto-central difference between go-P3 and no-go P3 is due to motor-related negativity overlapping P3 in the go case and positive relaxation of such negativity overlapping P3 in the no-go case, and that this motor-related activation may be identified by its having the same topography as the preceding CNV. Testing these suggestions meets with the problem of how to validly distinguish between P3 and the assumed overlapping continuing or downsweeping CNV. Distinguishing between overlapping components is a major reason why principal component analysis (PCA) has been applied, but the major criterion of conventional rotations (Varimax and Promax) is avoiding overlap. Trilinear component analysis (TCA) defines components independently of overlap, by their having stable topographies across time and observations. By applying TCA, we expected to obtain equal P3 components in go and no-go, and a preceding CNV component that would continue and overlap P3 with negative polarity in the go case and with positive polarity in the no-go case. We analyzed data from warned go/no-go tasks, separately for blocks with hand movements and eye movements. Different from expectation, TCA of the Hand task yielded three relevant components: parietal P3, only slightly affected by go vs. no-go, an overlapping CNV downturn unaffected by go vs. no-go, and an anterior-positive/posterior-negative bipolar N2-P3 that modeled the go/no-go effect. No convincing TCA solution was obtained in the Eye task. Possibilities and limitations of the TCA method are discussed.

Motor and non-motor inhibition in the Go/NoGo task: an ERP and fMRI study.

The contribution of movement-related activity to Go/NoGo ERP differences has been debated for 25 years. In this study, we examined ERP and fMRI measures of activity in twenty adults performing non-motor (count) and motor (right-handed button press) trials of the Go/NoGo task. Task performance was highly accurate and similar in the ERP and fMRI environments. No significant task-related effects were observed for the N2 component; however, we observed a substantial increase in positivity for Press NoGo compared to Count NoGo trials. The fMRI results also revealed significant deactivations for Press NoGo relative to Count NoGo trials in several left-lateralised motor-related areas, including the inferior frontal gyrus, precentral gyrus and supplementary motor area. Together, the results indicate that the P3 NoGo>Go effect in motor tasks is caused not by movement-related negativity on Go trials but by inhibition-related positivity on NoGo trials, and that this is associated with deactivation of motor areas involved in the Go response.

To go or not to go, that is the question: do the N2 and P3 reflect stimulus- or response-related conflict?

Several studies have linked increases in the N2 and P3 components to response conflict, evoked when multiple incompatible responses are simultaneously activated. However, these studies confound a change of response with a change of stimulus identity, and often a change in stimulus probability also. In two experiments, additional trial types were presented, which signified a change of stimulus, but still demanded the expected response. RT costs were observed when participants changed a planned response to a different one, and when they activated an unplanned response, but RT was not substantially increased for stimulus mismatch trials when these were clearly linked to the required response. N2 results were mixed and did not clearly favour a stimulus mismatch or response conflict interpretation. For the P3 component, stimulus-related differences were small but significant, with large increases in positivity when participants cancelled the planned response. Further experiments are required to determine the relative contribution of stimulus- and response-related conflict to N2.

Conflict and inhibition in the cued-Go/NoGo task.

OBJECTIVE: Current debate centres on the inhibitory and conflict interpretations of the N2 and P3 components of the event-related potential (ERP). We examined behavioural responses and ERPs in a cued-Go/NoGo task. METHODS: Participants were required to inhibit a planned response (NoGo target after Go cue), change a planned response to a different one (Invalid cueing), and activate an unexpected response (Go target after NoGo cue). RESULTS: Responses were slower when participants had to change a planned response, and execute an unplanned response. N2 was more negative whenever the presented target required a different response to what was expected based on the cue. In contrast, P3 was increased when participants had to change or inhibit a planned response, but not when executing a response where none was planned. CONCLUSIONS: N2 results lend support to the conflict account, while P3 reflects cancellation of a planned response. SIGNIFICANCE: This paper provides the first test of conflict involving activation of an unplanned response in a cued-Go/NoGo task.

Sequence effects support the conflict theory of N2 and P3 in the Go/NoGo task.

In two-choice tasks the preceding sequence of stimuli robustly influences both the P3 ERP component and reaction time (RT) to the current stimulus. We examined sequence effects in both two-choice and Go/NoGo tasks to distinguish between inhibition and conflict accounts of the N2 and P3 components. RT results suggested similar subjective expectancies were generated in the Go/NoGo and two-choice task. N2 was increased for all unexpected stimuli, even when no response inhibition was required, consistent with a conflict interpretation. The Go/NoGo P3 results also suggested a conflict explanation, and that this conflict was reduced if the response had been recently performed. These results support a reconsideration of the roles of N2 and P3 in all inhibition and conflict tasks, and the Go/NoGo task in particular.

Brain dynamics in the auditory oddball task as a function of stimulus intensity and task requirements.

We examined relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in an auditory oddball task, varying both stimulus intensity and active vs. passive task requirements between groups. We used a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). This study focused on the operation of three previously-reported phase-influenced mechanisms, involving prestimulus amplitudes, poststimulus amplitude changes, and the prestimulus contingent negative variation (CNV), in various EEG frequency bands. ERP responses to the standard stimuli were analysed. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz, and Pz. The occurrence of preferred phase-defined brain states was confirmed at a number of frequencies, crossing the traditional frequency bands. These preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and/or amplitude of all ERP components, and provided evidence of the operation of the three separate phase-influenced mechanisms. The preferred brain states occurred similarly across groups, suggesting that they reflect reflexive aspects of brain function associated with the timing of the stimuli, rather than voluntary attention. The impact on markers of cognitive function, such as the P3, suggests their important contributions to the efficiency of brain dynamics involved in perceptual and cognitive processing.

Anticipatory reconfiguration elicited by fully and partially informative cues that validly predict a switch in task.

Task-switching studies show no behavioral benefit of partially informative cues. However, ERP evidence of an early cue-locked positivity elicited by both fully and partially informative cues suggests that both cues trigger an anticipatory component of task set reconfiguration (Nicholson, Karayanidis, Davies, & Michie, 2006). We examined this apparent discrepancy using a cued-trials task-switching paradigm with three tasks. The ERP finding of an early cue-locked positivity was replicated for both switch-to cues, which validly predicted an upcoming switch trial and specified the new task set, and switch-away cues, which validly predicted an upcoming switch trial but not the new task set. This component was not elicited by a noninformative cue that did not specify whether the task would switch or repeat. Switch-away cues resulted in more accurate but not faster responding than did noninformative cues. Modeling of decision processes confirmed a speed-accuracy trade-off between these conditions and a preparation benefit for both switch-to and switch-away cues. These results indicate that both fully and partially informative cues elicit an early anticipatory component of task set reconfiguration that is reflected in the early cue-locked positivity. We argue that the pattern of results is most consistent with a task set inhibition account of this early anticipatory component of task set reconfiguration.

The combined effect of muscle contraction history and motor commands on human position sense.

Along with afferent information, centrally generated motor command signals may play a role in joint position sense. Isometric muscle contractions can produce a perception of joint displacement in the same direction as the joint would move if unrestrained. Contradictory findings of perceived joint displacement in the opposite direction have been reported. As this only occurs if muscle spindle discharge in the contracting muscle is initially low, it may reflect increased muscle spindle firing from fusimotor activation, rather than central motor command signals. Methodological differences including the muscle contraction task and use of muscle conditioning could underlie the opposing findings. Hence, we tested perceived joint position during two contraction tasks ('hold force' and 'hold position') at the same joint (wrist) and controlled muscle spindle discharge with thixotropic muscle conditioning. We expected that prior conditioning of the contracting muscle would eliminate any effect of increased fusimotor activation, but not of central motor commands. Muscle conditioning altered perceived wrist position as expected. Further, during muscle contractions, subjects reported wrist positions displaced ~12 degrees in the direction of contraction, despite no change in wrist position. This was similar for 'hold force' and 'hold position' tasks and occurred despite prior conditioning of the agonist muscle. However, conditioning of the antagonist muscle did reduce the effect of voluntary contraction on position sense. The errors in position sense cannot be explained by fusimotor activation. We propose that central signals combine with afferent signals to determine limb position and that multiple sources of information are weighted according to their reliability.