Christopher J. Brush

MAP training: combining meditation and aerobic exercise reduces depression and rumination while enhancing synchronized brain activity

Mental and physical (MAP) training is a novel clinical intervention that combines mental training through meditation and physical training through aerobic exercise. The intervention was translated from neuroscientific studies indicating that MAP training increases neurogenesis in the adult brain. Each session consisted of 30 min of focused-attention (FA) meditation and 30 min of moderate-intensity aerobic exercise. Fifty-two participants completed the 8-week intervention, which consisted of two sessions per week. Following the intervention, individuals with major depressive disorder (MDD; n=22) reported significantly less depressive symptoms and ruminative thoughts. Typical healthy individuals (n=30) also reported less depressive symptoms at follow-up. Behavioral and event-related potential indices of cognitive control were collected at baseline and follow-up during a modified flanker task. Following MAP training, N2 and P3 component amplitudes increased relative to baseline, especially among individuals with MDD. These data indicate enhanced neural responses during the detection and resolution of conflicting stimuli. Although previous research has supported the individual beneficial effects of aerobic exercise and meditation for depression, these findings indicate that a combination of the two may be particularly effective in increasing cognitive control processes and decreasing ruminative thought patterns.

Rumination in major depressive disorder is associated with impaired neural activation during conflict monitoring

Individuals with major depressive disorder (MDD) often ruminate about past experiences, especially those with negative content. These repetitive thoughts may interfere with cognitive processes related to attention and conflict monitoring. However, the temporal nature of these processes as reflected in event-related potentials (ERPs) has not been well-described. We examined behavioral and ERP indices of conflict monitoring during a modified flanker task and the allocation of attention during an attentional blink (AB) task in 33 individuals with MDD and 36 healthy controls, and whether their behavioral performance and ERPs varied with level of rumination. N2 amplitude elicited by the flanker task was significantly reduced in participants with MDD compared to healthy controls. Level of self-reported rumination was also correlated with N2 amplitude. In contrast, P3 amplitude during the AB task was not significantly different between groups, nor was it correlated with rumination. No significant differences were found in behavioral task performance measures between groups or by rumination levels. These findings suggest that rumination in MDD is associated with select deficits in cognitive control, particularly related to conflict monitoring.

Neurophysiological and behavioral correlates of cognitive control during low and moderate intensity exercise

The aim of this study was to examine neurophysiological and behavioral correlates of cognitive control elicited by a modified flanker task while exercising at low and moderate intensities. A secondary aim was to examine cognitive control processes at several time points during an acute bout of exercise to determine whether cognition is selectively influenced by the duration of exercise. Twenty-seven healthy participants completed a modified version of the Eriksen flanker task while exercising on a cycle ergometer at 40% and 60% VO2 peak and during a no-exercise seated control across three separate days. During task performance, continuous EEG was collected to assess neurocognitive function using the N2 and P3 event-related brain potentials (ERPs). Neurocognitive performance was assessed at 5, 15, and 25min time points during steady-state exercise. Regardless of intensity, behavioral findings revealed impaired accuracy during both exercise conditions for the flanker task trials that require greater cognitive control. However, faster reaction times were found during moderate-intensity exercise. Neuroelectric measures revealed increased N2 and P3 amplitudes during both exercise conditions relative to rest. Together, these findings suggest divergent effects of exercise on behavioral performance measures accompanied by an upregulation of cognitive control during aerobic exercise. These impairments are discussed in terms of dual-task paradigms and the transient hypofrontality theory.

Dose-Response and Time Course Effects of Acute Resistance Exercise on Executive Function.

The purpose of this study was to examine possible dose-response and time course effects of an acute bout of resistance exercise on the core executive functions of inhibition, working memory, and cognitive flexibility. Twenty-eight participants (14 female; Mage = 20.5 ± 2.1 years) completed a control condition and resistance exercise bouts performed at 40%, 70%, and 100% of their individual 10-repetition maximum. An executive function test battery was administered at 15 min and 180 min postexercise to assess immediate and delayed effects of exercise on executive functioning. At 15 min postexercise, high-intensity exercise resulted in less interference and improved reaction time (RT) for the Stroop task, while at 180 min low- and moderate-intensity exercise resulted in improved performance on plus-minus and Simon tasks, respectively. These findings suggest a limited and task-specific influence of acute resistance exercise on executive function in healthy young adults.

Using event-related potentials to study the effects of chronic exercise on cognitive function

In recent years, advancements in neuroscientific methods have led to considerable progress with regard to the nature of the relationship between exercise and cognitive function. This review focuses on several components of the event-related potential (ERP) and how they can be successfully used to better understand subtle aspects of cognition that may be influenced by regular exercise participation. A select review of research that has incorporated ERPs to study the relationship between chronic exercise participation or cardiorespiratory fitness and cognitive function is presented followed by a brief overview of important methodological considerations when using the ERP technique. Future directions for the application of ERPs to achieve a more comprehensive understanding of the effects of chronic exercise on cognitive function are offered.

A randomized trial of aerobic exercise on cognitive control in major depression

OBJECTIVE The aim of this study was to examine the effects of an 8-week moderate-intensity aerobic exercise training intervention on cognitive control in individuals with major depressive disorder (MDD). METHODS Participants with a current diagnosis of MDD (n=30; 21.1±2.0years) were stratified by depressive symptoms and randomized to an 8-week intervention of aerobic exercise (AE) or placebo exercise (PE). AE consisted of three sessions/week of moderate-intensity exercise training while PE consisted of three sessions/week of light-intensity stretching. Cognitive control was assessed pre- and post-treatment using behavioral performance (i.e., reaction time and accuracy) and event-related potentials (i.e., N2 amplitude). Depressive symptoms and rumination were also assessed before and after the intervention. RESULTS Compared with PE, the AE treatment arm was associated with an increase in N2 amplitude to incongruent flanker task trials, reflecting an increase in cognitive control processes. Symptoms of depression also decreased after AE although the treatments did not differ in their effects on rumination. Exploratory mediation analysis indicated that changes in N2 amplitude did not mediate pre-to-post treatment reductions in depressive symptoms. CONCLUSIONS An 8-week moderate-intensity AE program is associated with improved neural indices of conflict monitoring and reduced depressive symptoms among individuals with MDD. SIGNIFICANCE Future research examining the influence of exercise in combination with behavioral and pharmacological treatments for neurocognitive function in MDD is warranted.

Do sport-related concussions result in long-term cognitive impairment? A review of event-related potential research

Sport-related concussions have become a major public health concern although the long-term effects on cognitive function remain largely unknown. Event-related potentials (ERPs) are ideal for studying the long-term impact of sport-related concussions, as they have excellent temporal precision and provide insight that cannot be obtained from behavioral or neuropsychological measures alone. We reviewed all available published studies that have used stimulus or response-locked ERPs to document cognitive control processes in individuals with a history of concussion. Collectively, cross-sectional evidence suggests consistent reductions in P3 amplitude in previously concussed individuals, as well as a possible impairment in cognitive processing speed (P3 latency) and error monitoring processes (ERN). The persistent neurophysiological changes found may be related to the number of previous concussions sustained and the time since injury. Future studies incorporating prospective research designs are warranted before definitive statements can be offered regarding the long-term impact of sport-related concussions on cognitive control.

Psychophysiological and ergogenic effects of music in swimming

We investigated the effects of listening to medium-to-fast tempo asynchronous music on performance, heart rate (HR), perceived exertion, and affect during an acute bout of swimming at a self-selected pace. Healthy college-aged recreational swimmers (n=20; M age =20.3±2.0 years) were studied on two occasions in randomised order: swimming 1,200 m while listening to music (125-140 beats per minute) or during a no-music control trial. Following a period of habituation to the SwiMP3 audio player, HR, rating of perceived exertion, feeling scale responses and performance time trials were assessed for each 200 m during the 1,200 m freestyle swimming trial, each interspersed with a one min rest period. Participants swam significantly faster during the asynchronous music condition relative to control (P<0.01, η 2 =0.32). Although music had no significant influence on perceived exertion, the music condition was associated with more favourable arousal (P<0.01, η 2 =0.40) and affective (P<0.05, η 2 p =0.19) responses. These findings suggest that both recreational and competitive swimmers may benefit from the use of underwater MP3 players and music.

A history of sport-related concussion is associated with sustained deficits in conflict and error monitoring

Previous research has demonstrated long-term deficits in neurocognitive function in individuals with a history of sport-related concussion. The purpose of this study was to examine the relationship between a history of concussion and behavioral and event-related potential (ERP) indices of pre- and post-response conflict and error monitoring. A secondary aim was to determine whether years of high risk sport participation were related to impairments in these cognitive control processes. Forty-seven former athletes (age = 20.8 ± 2.2 years) with (n = 25; 5 females) and without (n = 22; 9 females) a history of concussion completed a modified flanker task while behavioral performance, N2, error-related negativity (ERN), and error positivity (Pe) components were assessed. An increase in post-response error-related (ERN) brain activity and a nonsignificant trend of increased pre-response conflict (N2) was observed in individuals with a prior sport-related concussion relative to non-concussed controls; however, no behavioral performance differences were found between groups. No significant associations were found between ERP and behavioral measures and the number of years of high-risk sport participation; however, time since last head injury was associated with shorter N2 latency. Together, these findings suggest a persistent impairment in cognitive control and error-related processing in individuals with a history of concussion. These findings are interpreted within the framework of the compensatory error-monitoring hypothesis.

Using multilevel modeling to examine blunted neural responses to reward in major depression

BACKGROUND Major depressive disorder (MDD) is a pernicious disorder characterized by deficits in reward processing. A better understanding of these deficits may help to elucidate the underlying pathophysiology and guide treatment development. METHODS This study assessed reward positivity and feedback negativity event-related potentials and their difference scores elicited in response to monetary gains and losses among 100 young adults (52 with MDD). Multilevel modeling was used to assess individual- and trial-level change in neural responses over time. RESULTS Trial-level analyses indicated that a diagnosis of MDD and depressive symptom severity significantly moderated the trajectory of reward positivity, with individuals with higher symptoms of depression demonstrating less sensitivity to rewards over time. CONCLUSIONS These results provide further support for reward dysfunction in MDD and highlight important individual differences in the trajectory of neural responses to reward. Future studies are warranted to investigate reward sensitivity over time to elucidate important individual- and trial-level differences in reward processing.