Groove rhythm stimulates prefrontal cortex function in groove enjoyers

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Groove rhythm stimulates prefrontal cortex function in groove enjoyers

• Takemune Fukuie,
• Kazuya Suwabe,
• Satoshi Kawase,
• Takeshi Shimizu,
• Genta Ochi,
• Ryuta Kuwamizu,
• Yosuke Sakairi &
• Hideaki Soya 

Scientific Reports volume 12, Article number: 7377 (2022) Cite this article

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Abstract

Hearing a groove rhythm (GR), which creates the sensation of wanting to move to the music, can also create feelings of pleasure and arousal in people, and it may enhance cognitive performance, as does exercise, by stimulating the prefrontal cortex. Here, we examined the hypothesis that GR enhances executive function (EF) by acting on the left dorsolateral prefrontal cortex (l-DLPFC) while also considering individual differences in psychological responses. Fifty-one participants underwent two conditions: 3 min of listening to GR or a white-noise metronome. Before and after listening, participants performed the Stroop task and were monitored for l-DLPFC activity with functional near-infrared spectroscopy. Our results show that GR enhanced EF and l-DLPFC activity in participants who felt a greater groove sensation and a more feeling clear-headed after listening to GR. Further, these psychological responses predict the impact of GR on l-DLPFC activity and EF, suggesting that GR enhances EF via l-DLPFC activity when the psychological response to GR is enhanced.

Introduction

A growing amount of evidence shows that physical exercise has beneficial effects on cognitive functions¹, especially on human executive function (EF) mainly in the prefrontal cortex (PFC)². Our recent study using acute exercise with music showed that the key factor of exercise’s effect on prefrontal executive function is a positive affective response³ expressed the two-dimensional axis of pleasure and arousal.

Another potential stimulus which can improve EF through a positive affective response is groove rhythm (GR). GR is a musical rhythm that induces the sensation of “Wanting to move to the music” (groove sensation) accompanied by positive affective responses while listening to music^4,5. GR can be defined by the subjective score of “Wanting to move to the music” and “Good nori”^4,6. The groove sensation can be modulated by syncopation. Syncopation is a method of shifting rhythmic emphasis by manipulating the complexity of a rhythm. Rhythm with low to medium syncopation induces a higher groove sensation than does rhythm with high syncopation as evidenced by averages of mass groups in previous studies^7,8,9. Low-frequency components, such as the bass drum, induce entrainment of body movement and musical beat¹⁰. In several previous studies, drum breaks consisting of hi-hat, snare-drum, and bass-drum sounds were used because they made it easy to control rhythmic factors, syncopation, bass sound, and tempo^{7,8,9,10,11,12}.

Moving the body to music is a universal phenomenon (e.g., clapping, nodding, swaying) and one of the main powers of music¹³. Music with groove-inducing characteristics increasing in recent music popularity charts may be indicative of this¹⁴. That groove music improves gait performance in Parkinson’s disease (PD) by reducing the cognitive demands of synchronizing to the beat and promoting vigorous movement^15,16,17 shows that groove music affects the interaction between body movement and brain function. More interestingly, listening to groove music induces entrainment of body movement and musical rhythm together with positive affective responses¹⁸ and activates neural networks associated with motor and reward systems^11,19,20. Since the dopaminergic reward system projects not only to emotion-related brain areas but also to cognition-related areas such as the PFC^21,22,23, GR could increase PFC activity and lead to improved EF. However, no research has explored the effect of groove music on EF and prefrontal activity to date. The reason for this could be that the effect of GR on EF may have large individual differences because both groove sensation and concurrent positive affective responses to groove music would have many individual differences^8,24 and both responses are associated with reward system activity¹¹. Therefore, we should examine the single effects of GR on EF and its relationship with PFC activity. To examine this, consideration of the psychological responses to listening to GR as influential factors that explain individual differences and creation of an experimental model which can evaluate the effect of GR on EF and how it is related to PFC activity are necessary.

To that end, in the current study we introduce the combination of an acute experimental model that was used for the detection of exercise’s effect on cognition and prefrontal activity and a grouping analysis to explore the psychological response to GR. In our previous research, we used functional near-infrared spectroscopy (fNIRS) with the color-word-matching Stroop task (CWST)^25,26, which evaluates inhibitory EF, in order to clarify the effects of an acute bout (10 min) of exercise^{27,28,29,30,31}. fNIRS is a non-invasive neuroimaging method which can monitor hemodynamic response to neural activation (neurovascular coupling)³² by using near-infrared light passing through tissue. Since fNIRS allows for the least restrictive measuring environment among neuroimaging modalities, it can measure regional cortical activation boosted by listening to music while minimizing possible negative environmental influences on psychological response and cognition. The CWST has been adopted in numerous neuroimaging studies including fNIRS studies^33,34,35, and the brain regions related with the task are well known. The DLPFC is a key region for inhibitory control of EF³⁶ and responsible for CWST performance^37,38. In addition, the left hemisphere plays a key role in the processing of verbal information^39,40,41,42. Therefore, we focused on the left dorsolateral prefrontal cortex (l-DLPFC) as the region of interest (ROI). A previous study indicated that l-DLPFC activity correlated with a positive affective response and that EF changed with a single bout of exercise with music³. Therefore, in the current study, the CWST was performed before and after listening to GR while monitoring l-DLPFC activity using fNIRS. In addition to this acute model, cluster analysis using the subjective senses of both groove sensation and psychological state when listening to GR was introduced, and we tried to reveal the individual differences in the effect of listening to GR on EF and task-related l-DLPFC activity.

GR elicits groove sensation and concurrent positive affective response, but it is not known whether it enhances inhibitory EF with l-DLPFC activity as a result. The purpose of this study is to determine whether GR enhances EF and l-DLPFC activity, focusing on individual differences in psychological responses to GR. Our working hypothesis is that GR presented as drum breaks with low to medium syncopation enhances CWST performance with task-related l-DLPFC activation. Furthermore, the effects can be remarkable in participants who experience a higher groove sensation and positive psychological state. This study will allow us to look ahead to new aspects of the effect of GR, for example a potential cumulative effect with exercise.

Results

Physical load and psychological measures

Physical load and psychological measures for each experimental condition for all participants are shown in Table 1. Paired t tests were conducted over condition (WM, GR). We confirmed that there were no differences in HR between conditions (t(48) = − 0.983, P = 0.33). GR elicited significantly higher scores compared to WM in these items: “Good nori” (t(50) = − 11.99, P < 0.001), “Wanting to move to the music” (t(50) = − 9.17, P < 0.001), “Feeling like my body is resonating with the rhythm” (t(50) = − 5.62, P < 0.001), “Having fun” (t(50) = − 11.62, P < 0.001), “Excited” (t(50) = − 9.00, P < 0.001), and “Feeling clear-headed” (t(50) = − 4.16, P < 0.001). WM elicited significantly higher scores compared to GR in these items: “Struggling to synchronize with the beat” (t(50) = 4.35, P < 0.001), “Bored” (t(50) = 10.73, P < 0.001), “Wanting to stop listening” (t(50) = 6.48, P < 0.001), and “Feeling discomfort” (t(50) = 5.18, P < 0.001).

Table 1 Summary of results for physical load and psychological measures for all participants. Data are presented as mean (SD).

Full size table

Stroop task performance and l-DLPFC activity

We confirmed whether the Stroop interference could be observed in this experiment (Fig. 1A-C). Reaction time (RT) and error rate (ER) were subjected to a repeated measures three-way ANOVA with task condition (Neutral, Incongruent), experimental condition (GR, WM), and time (Pre, Post) being within-subject factors. The ANOVA for RT and ER exhibited significant main effects of task condition (F(1,50) = 210.06, P < 0.001, Fig. 1A, F (1,50) = 40.15, P < 0.001, Fig. 1B, respectively). We confirmed that the incongruent condition was more difficult than the neutral condition, and Stroop interference occurred in the present study. In the same way, for fNIRS data, l-DLPFC activity exhibited significant main effects of task condition: l-DLPFC oxy-Hb change during the incongruent condition was significantly larger than that during the neutral condition (F(1,50) = 14.80, P < 0.001, Fig. 1C).

Figure 1

(A) Reaction time (RT) of neutral and incongruent conditions of the Stroop task. (B) Error rate (ER) of neutral and incongruent conditions of the Stroop task. (C) l-DLPFC oxy-Hb for neutral and incongruent conditions. Slower RT and higher ER in the incongruent condition exhibited significant Stroop interference effects. (D) Stroop interference against RT for the Stroop task. The repeated measures two-way ANOVA revealed no significant differences. (E) Stroop interference against l-DLPFC oxy-Hb. The repeated measures two-way ANOVA revealed no significant differences. Values are represented as box plots where the bottom, middle, and top lines of the boxes are the 25th, 50th (median), and 75th percentiles, respectively, and the whiskers above and below each box indicate the most extreme point within 1.5 times the interquartile range. The points above or below the whiskers represent outliers. ***P < 0.001.

Full size image

Stroop RT_neutral, RT_incongruent, RT_interference, l-DLPFC oxy-Hb_neutral, l-DLPFC oxy-Hb_incongruent, and l-DLPFC oxy-Hb_interference were subjected to repeated measures two-way ANOVA with condition (WM, GR) and time (Pre, Post) as within-subject factors (Fig. 1D, E). For Stroop RT_neutral, RT_incongruent, there was a main effect of time. Both Stroop RT_neutral and RT_incongruent were shorter for post-task than for pre-task (F(1,50) = 25.02, P < 0.001 and F(1,50) = 15.18, P < 0.001, respectively). There was no significant change of RT_interference (F(1,50) = 1.33, P = 0.25), l-DLPFC oxy-Hb_neutral (F(1,50) = 0.89, P = 0.34), l-DLPFC oxy-Hb_incongruent (F(1,50) = 0.78, P = 0.37), or l-DLPFC oxy-Hb_interference (F(1,50) = 0, P = 0.99) before or after listening for either of the GR or WM conditions.