白學(xué)軍 張琪涵 章 鵬 周 菘 劉 穎 宋 星 彭國(guó)慧

(天津師范大學(xué)心理與行為研究院,天津 300074)

1 前言

運(yùn)動(dòng)想象(motor imagery,MI)是一個(gè)動(dòng)態(tài)的過程,指人們?cè)谛睦锬M動(dòng)作而不伴隨任何的身體運(yùn)動(dòng)(Jeannerod,1994,2006)。運(yùn)動(dòng)想象包含視覺想象和動(dòng)覺想象,前者需要從第一人稱或第三人稱的視角看到自己完成動(dòng)作;后者需要人們真實(shí)地感覺到自己完成動(dòng)作。目前MI在臨床和專業(yè)領(lǐng)域上被廣泛應(yīng)用。MI是一種基于想象的心理練習(xí),能夠提高運(yùn)動(dòng)員(Cumming &Hall,2002;Murphy,1994;Roure et al.,1999)、音樂家(Langheim,Callicott,Mattay,Duyn,&Weinberger,2002;Meister et al.,2004;Pascual-Leone et al.,1995;Yue &Cole,1992)或者高級(jí)手工技師(例如外科醫(yī)生,Rogers,2006)的行為表現(xiàn)。另外,Decety和Grèzes (2006)認(rèn)為運(yùn)動(dòng)控制是運(yùn)動(dòng)過程與感覺、認(rèn)知過程不斷交互的結(jié)果。皮層可塑性理論認(rèn)為大腦皮層功能、皮層間的聯(lián)結(jié)等可以根據(jù)外界刺激的變化而變化,訓(xùn)練可以改變大腦結(jié)構(gòu)(Fiorio,Tinazzi,&Aglioti,2006)。所以那些運(yùn)動(dòng)功能損傷的病人,可以通過不斷地鍛煉,來(lái)改善、塑造大腦皮層,繼而實(shí)現(xiàn)運(yùn)動(dòng)功能的康復(fù)。因此,運(yùn)動(dòng)想象在神經(jīng)系統(tǒng)損傷病人的康復(fù)治療上也具有一定的影響作用(Braun,Beurskens,Borm,Schack,&Wade,2006;Jackson,Lafleur,Malouin,Richards,&Doyon,2001;Johnson-Frey,2004;Lotze&Halsband,2006;Sharma,Pomeroy,&Baron,2006;Weiss et al.,1994)。

已有研究發(fā)現(xiàn),運(yùn)動(dòng)想象與運(yùn)動(dòng)執(zhí)行有幾點(diǎn)共性：(1)在時(shí)間進(jìn)程上運(yùn)動(dòng)想象與運(yùn)動(dòng)執(zhí)行存在高度相關(guān)(Decety,Jeannerod,&Prablanc,1989);(2)運(yùn)動(dòng)想象任務(wù)下自主神經(jīng)系統(tǒng)的外周反應(yīng)與運(yùn)動(dòng)執(zhí)行任務(wù)下的相似,例如心跳(Decety,Jeannerod,Durozard,&Baverel,1993;Decety,Jeannerod,Germain,&Pastene,1991;Fusi et al.,2005);(3)運(yùn)動(dòng)執(zhí)行和運(yùn)動(dòng)想象任務(wù)引起了相似的皮電反應(yīng)(Guillot,Collet,&Dittmar,2004;Guillot,Haguenauer,Dittmar,&Collet,2005);(4)隨著大腦影像技術(shù)的發(fā)展,研究者使用fMRI (functional magnetic resonance imaging)、PET(positron emission tomography)、TMS (Transcranial magnetic stimulation)等技術(shù),探索這兩種任務(wù)下的腦機(jī)制,發(fā)現(xiàn)運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象基本上激活了相似的神經(jīng)機(jī)制(Guillot et al.,2008;Mellet,Petit,Mazoyer,Denis,&Tzourio,1998)或者這兩者的神經(jīng)網(wǎng)絡(luò)至少部分重疊(Gerardin et al.,2000)。具體來(lái)說(shuō),共享的重疊區(qū)域主要包括輔助運(yùn)動(dòng)皮層(SMA)、前運(yùn)動(dòng)皮層(PMA)、初級(jí)感覺區(qū)(M1/S1)、后頂葉(PPL)、紋狀體、小腦、丘腦(Gerardin et al.,2000;Lotze et al.,1999;Munzert,Lorey,&Zentgraf,2009;Zhang et al.,2011)。

然而,研究者對(duì)初級(jí)感覺區(qū)(M1/S1)激活存在一些爭(zhēng)議。前人研究分別觀察到了主運(yùn)動(dòng)區(qū)的激活(Solodkin,Hlustik,Chen,&Small,2004;Sharma,Jones,Carpenter,&Baron,2008)、短暫激活(Dechent,Merboldt,&Frahm,2004)或者不激活(Lotze,Scheler,Tan,Braun,&Birbaumer,2003)。近期 Hétu 等人(2013)對(duì)運(yùn)動(dòng)想象神經(jīng)網(wǎng)絡(luò)相關(guān)的122個(gè)實(shí)驗(yàn)(來(lái)自75篇論文)進(jìn)行了元分析,發(fā)現(xiàn)其中僅有22個(gè)實(shí)驗(yàn)(來(lái)自 16篇論文)報(bào)告了運(yùn)動(dòng)想象任務(wù)激活主運(yùn)動(dòng)皮層。研究結(jié)果的不一致可能是由以下原因引起的：(1)實(shí)驗(yàn)任務(wù)變量：實(shí)驗(yàn)程序(Sharma et al.,2008)、任務(wù)類型(Dechent et al.,2004;Fourkas,Ionta,&Aglioti,2006;Wolbers,Weiller,&Büchel,2003)、任務(wù)復(fù)雜性(Holpe &Wolf,2011;Kuhtz-Buschbeck et al.,2003)等;(2)個(gè)體差異：專業(yè)水平(Lotze et al.,2003;Milton,Small,&Solodkin,2008;Chang et al.,2011)、想象力(Amedi,Malach,&Pascual-Leone,2005;Cui,Jeter,Yang,Montague,&Eagleman,2007;Guillot et al.,2008;van der Meulen,Allali,Rieger,Assal,&Vuilleumier,2014)、性別(Lissek et al.,2007;Schuster et al.,2011)、年齡(Personnier,Ballay,&Papaxanthis,2010;Schuster et al.,2011)等;(3)探測(cè)方法：相比于fMRI、PET研究,大量的TMS研究都為MI增強(qiáng)主運(yùn)動(dòng)皮層的興奮性提供了實(shí)證證據(jù)(Loporto,McAllister,Williams,Hardwick,&Holmes,2012);(4)最近 Raffin,Mattout,Reilly和 Giraux(2012)的研究發(fā)現(xiàn)在動(dòng)覺運(yùn)動(dòng)想象任務(wù)下輔助運(yùn)動(dòng)皮層對(duì)主運(yùn)動(dòng)皮層起抑制作用。

近期的一些研究發(fā)現(xiàn)運(yùn)動(dòng)強(qiáng)度能夠影響主運(yùn)動(dòng)皮層的激活。例如Shibusawa 等(Shibusawa,Takeda,Nakajima,Ishigami,&Sakatani,2009;Shibusawa et al.,2010)用fNIRS (functional near-infrared spectroscopy)監(jiān)測(cè)人們分別用最大握力的20%、50%、80%的力量進(jìn)行抓握任務(wù)時(shí)主運(yùn)動(dòng)皮層和體感皮層內(nèi)氧合血紅蛋白的濃度變化。發(fā)現(xiàn)不同力量強(qiáng)度的抓握任務(wù)其觀測(cè)皮層上的氧合血紅蛋白濃度差異顯著。還有一些研究也發(fā)現(xiàn)主運(yùn)動(dòng)皮層的激活程度存在隨力量強(qiáng)度水平的增強(qiáng)而升高的趨勢(shì)(Derosière et al.,2013;Shibuya,Kuboyama,&Tanaka,2014)。甚至一些較小的力量強(qiáng)度變化(最大握力的 1%～10%)也會(huì)引起主運(yùn)動(dòng)皮層激活程度的正性改變(Kuhtz-Buschbeck et al.,2008)。那么增強(qiáng)運(yùn)動(dòng)想象任務(wù)的想象強(qiáng)度是否也能夠引起主運(yùn)動(dòng)皮層的激活變化？在運(yùn)動(dòng)執(zhí)行任務(wù)下相關(guān)皮層激活程度隨力量強(qiáng)度變化的原因可能來(lái)源于外周體覺信息的傳入或者是運(yùn)動(dòng)控制。如果變化原因是由體覺信息傳入引起的,那么運(yùn)動(dòng)(想象)強(qiáng)度僅會(huì)影響運(yùn)動(dòng)執(zhí)行任務(wù)下相關(guān)皮層的激活水平;如果是由運(yùn)動(dòng)控制引起的,那么運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象任務(wù)下探測(cè)皮層都會(huì)受到運(yùn)動(dòng)(想象)強(qiáng)度的影響。但目前對(duì)想象強(qiáng)度在運(yùn)動(dòng)想象任務(wù)下的作用情況的研究相對(duì)較少,有些研究者雖采用fNIRS考察了不同力量強(qiáng)度、速度下運(yùn)動(dòng)想象任務(wù)的皮層信號(hào)變化,但其主要探究力量強(qiáng)度和速度對(duì)應(yīng)反應(yīng)信號(hào)的精確分類,沒有單純地比較不同想象強(qiáng)度對(duì)探測(cè)皮層的影響作用。能夠確定的是想象強(qiáng)度影響主運(yùn)動(dòng)皮層內(nèi)氧合血紅蛋白濃度變化,因?yàn)殡S著運(yùn)動(dòng)想象強(qiáng)度的逐步增加,主運(yùn)動(dòng)皮層內(nèi)的氧合血紅蛋白濃度也是逐步增高的,但是否達(dá)統(tǒng)計(jì)學(xué)上顯著還需進(jìn)一步檢驗(yàn)(Xu et al.,2014;Yin et al.,2015)。另外,Mizuguchi,Nakata 和Kanosue (2014)使用fMRI探究了前運(yùn)動(dòng)-頂葉皮層活動(dòng)與想象強(qiáng)度水平的關(guān)系,發(fā)現(xiàn)前額葉皮層、輔助運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層、腦島、頂下小葉的激活情況受想象強(qiáng)度的影響,沒有報(bào)告主運(yùn)動(dòng)區(qū)與想象強(qiáng)度間的變化關(guān)系。所以,目前想象強(qiáng)度對(duì)運(yùn)動(dòng)想象腦機(jī)制的影響作用還不明確。

此外,與fMRI、PET等技術(shù)相比,功能性近紅外光譜成像技術(shù)(fNIRS) (Brickman et al.,2005;Hock et al.,1997)有其獨(dú)特的優(yōu)勢(shì)。fNIRS的操作簡(jiǎn)便、造價(jià)低、對(duì)人體無(wú)損傷、便攜性好、時(shí)間分辨率和空間分辨率較高等;適用于自然情境、嬰幼兒童和特殊人群的認(rèn)知神經(jīng)科學(xué)研究(劉寶根,周兢,李菲菲,2011;楊炯炯,駱清銘,2002)。由于fNIRS對(duì)被試實(shí)驗(yàn)過程中的動(dòng)作不是特別敏感,對(duì)運(yùn)動(dòng)具有較高的寬容度,所以相比于對(duì)運(yùn)動(dòng)敏感的 fMRI,fNIRS為運(yùn)動(dòng)領(lǐng)域內(nèi)腦功能活動(dòng)的研究開辟了一條新路,提高了該領(lǐng)域研究的生態(tài)效度。Leff等(2011)曾對(duì)基于 fNIRS的運(yùn)動(dòng)任務(wù)腦活動(dòng)研究進(jìn)行系統(tǒng)性的回顧,認(rèn)為這一技術(shù)有利于自然情境下的運(yùn)動(dòng)技能學(xué)習(xí)、運(yùn)動(dòng)控制、運(yùn)動(dòng)員表現(xiàn)、神經(jīng)疾病康復(fù)等內(nèi)部機(jī)制的探索。

綜上所述,本研究采用fNIRS技術(shù),通過控制運(yùn)動(dòng)(想象)強(qiáng)度來(lái)考察被試完成運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象任務(wù)時(shí)大腦皮層血氧濃度變化。實(shí)驗(yàn)采用舉啞鈴這一簡(jiǎn)單運(yùn)動(dòng)任務(wù)、動(dòng)覺想象這一想象任務(wù)類型來(lái)控制任務(wù)相關(guān)變量對(duì)監(jiān)測(cè)結(jié)果的影響;選取具有一定想象能力、非體育專業(yè)的青年被試參與正式實(shí)驗(yàn),盡可能的排除掉被試相關(guān)變量帶來(lái)的干擾;fNIRS在運(yùn)動(dòng)領(lǐng)域內(nèi)應(yīng)用的生態(tài)效度較高、對(duì)運(yùn)動(dòng)方面的限制較少。所以在控制了這些無(wú)關(guān)變量之后,運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象的激活模式很可能十分相似,運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象任務(wù)下都會(huì)激活主運(yùn)動(dòng)皮層;另外,想象強(qiáng)度對(duì)運(yùn)動(dòng)想象任務(wù)下大腦活動(dòng)的影響也很可能與運(yùn)動(dòng)執(zhí)行任務(wù)下的變化保持一致,即想象強(qiáng)度不會(huì)改變大腦激活模式,但會(huì)影響皮層的激活水平。

2 方法

2.1 被試

(1)使用握力計(jì)篩選被試。其中男性握力在37.7～56.6 kg之中,女性握力在 21.8～35.0 kg之中。

(2)實(shí)驗(yàn)被試非體育專業(yè);在啞鈴運(yùn)動(dòng)或啞鈴運(yùn)動(dòng)相關(guān)腦區(qū)上沒有主觀或客觀癥狀;無(wú)心血管、肺腎、神經(jīng)障礙等方面疾病;沒有進(jìn)行過艱苦訓(xùn)練;實(shí)驗(yàn)前沒進(jìn)食過含咖啡因的食物或飲料。

(3)通過《運(yùn)動(dòng)想象問卷-修訂版》(MIQ-RS)(Gregg,Hall,&Butler,2010)篩選出具有動(dòng)覺想象能力的被試,即選擇動(dòng)覺想象平均難易程度大于4“一般”的被試參與正式實(shí)驗(yàn)。

(4)15名右利手健康的男性志愿者(平均握力47.2 ± 4.08 kg)和15名右利手健康的女性志愿者(平均握力27.1 ± 3.47 kg)參加了正式實(shí)驗(yàn)。男性被試的平均年齡為24.3 ± 1.49歲,女性被試的平均年齡為23.8 ± 0.77歲。每位被試在實(shí)驗(yàn)后獲得25元報(bào)酬。

2.2 實(shí)驗(yàn)設(shè)備

采用島津公司生產(chǎn)的LABNIRS功能性近紅外光譜成像儀(LABNIRS/16,Shimadzu Corporation,Kyoto,Japan),通過三波長(zhǎng)(780 ± 5 nm、805 ± 5 nm、830 ±5 nm)的近紅外線半導(dǎo)體激光(被歸為 IED-60825-1標(biāo)準(zhǔn)下的 1M 級(jí)),根據(jù)修訂后的比爾-朗伯(吸收)定律(modified Beer-Lambert law,MBLL)得到探測(cè)區(qū)域下氧合血紅蛋白濃度(HbO)、脫氧血紅蛋白濃度(HbR)、總血紅蛋白濃度(HbT)的變化。采樣率設(shè)置為11 Hz。因HbO指標(biāo)對(duì)任務(wù)刺激的變化更加敏感(Hoshi,Kobayashi,&Tamura,2001),所以著重分析HbO的變化。

2.3 材料

2.3.1 《運(yùn)功想象問卷-修訂版》

《運(yùn)功想象問卷-修訂版》(MIQ-RS)由7個(gè)視覺想象問題和7個(gè)動(dòng)覺想象問題組成(Gregg et al.,2010)。采用7點(diǎn)評(píng)分,從1“非常困難”到7“非常容易”。使用該想象力問卷篩選出動(dòng)覺想象平均難易程度大于 4“一般”的被試,參與正式實(shí)驗(yàn)。分別有右利手、健康的15名男性志愿者和15名女性志愿者參加了正式實(shí)驗(yàn)。表1是被試想象力的測(cè)試結(jié)果。

表1 想象力測(cè)試結(jié)果

結(jié)果顯示：男性的平均想象力得分為5.98,女性的平均想象力得分為 5.55,都處于 5“有些容易”到 6“容易”之間。經(jīng)統(tǒng)計(jì)檢驗(yàn),男性、女性的動(dòng)覺想象力無(wú)顯著差異,

t

(28)=1.61,

p

＞0.05。

2.3.2 自編《運(yùn)動(dòng)想象自評(píng)問卷》

《運(yùn)動(dòng)想象自評(píng)問卷》的目的在于被試完成運(yùn)動(dòng)想象任務(wù)后對(duì)其想象品質(zhì)的評(píng)定。采用7點(diǎn)量表,被試從 1“無(wú)法想象”到 7“非常容易”;以及對(duì)不同強(qiáng)度運(yùn)動(dòng)想象任務(wù)間差異的評(píng)價(jià),從 1“差異巨大”到7“沒有差異”。

2.4 實(shí)驗(yàn)設(shè)計(jì)

本實(shí)驗(yàn)采用 2任務(wù)類型(運(yùn)動(dòng)執(zhí)行任務(wù),運(yùn)動(dòng)想象任務(wù))×2運(yùn)動(dòng)強(qiáng)度(4磅,8磅/2磅,4磅)的被試內(nèi)設(shè)計(jì)。已有研究發(fā)現(xiàn)運(yùn)動(dòng)疲勞時(shí)運(yùn)動(dòng)皮層內(nèi)的氧合血紅蛋白濃度明顯下降(Shibuya &Tachi,2006;Shibuya &Kuboyama,2007)。Kuhtz-Buschbeck 等人(2008)發(fā)現(xiàn)較小強(qiáng)度的力量變化也能夠影響到主運(yùn)動(dòng)皮層的激活水平。所以為了排除疲勞的干擾,本研究采用平均最大握力的3.6%和7.2%的力量強(qiáng)度,即男性與之對(duì)應(yīng)的重量約為4磅、8磅的啞鈴,女性與之對(duì)應(yīng)的重量約為2磅、4磅的啞鈴。

2.5 實(shí)驗(yàn)程序

在正式實(shí)驗(yàn)之前,招募5名男性右利手健康被試,平均年齡24.3歲,平均握力42.7 kg。這些被試不再參與正式實(shí)驗(yàn)。要求他們做6組啞鈴運(yùn)動(dòng),每組啞鈴運(yùn)動(dòng)包括1次4磅啞鈴運(yùn)動(dòng)和1次8磅啞鈴運(yùn)動(dòng),隨機(jī)呈現(xiàn)。被試要分別對(duì)做4組啞鈴運(yùn)動(dòng)和做6組啞鈴運(yùn)動(dòng)的意志疲勞程度進(jìn)行評(píng)價(jià)(7點(diǎn)評(píng)分,1“無(wú)疲勞”,7“非常疲勞”)。結(jié)果顯示,被試做 4 組啞鈴運(yùn)動(dòng)的意志疲勞程度為 4.2,做 6組啞鈴運(yùn)動(dòng)的抑制疲勞程度為5.8。這說(shuō)明4次4磅啞鈴運(yùn)動(dòng)和4次8磅啞鈴運(yùn)動(dòng)達(dá)不到運(yùn)動(dòng)疲勞狀態(tài)。

另外對(duì)于女性來(lái)說(shuō),為了控制被試不達(dá)到運(yùn)動(dòng)疲勞,同樣在正式實(shí)驗(yàn)前招募5名女性右利手健康被試,平均年齡23.5歲,平均握力26.7 kg,不再參與正式實(shí)驗(yàn)。除了將8磅啞鈴換成了2磅啞鈴?fù)?其余同男性的實(shí)驗(yàn)前操作。結(jié)果顯示,被試做4組啞鈴運(yùn)動(dòng)的意志疲勞程度為 4,做6組啞鈴運(yùn)動(dòng)的意志疲勞程度為 5.6。這說(shuō)明4次2磅啞鈴運(yùn)動(dòng)和 4次4磅啞鈴運(yùn)動(dòng)達(dá)不到運(yùn)動(dòng)疲勞狀態(tài)。

正式實(shí)驗(yàn)。為了避免視覺想象的干擾,運(yùn)動(dòng)指令以聲音的形式呈現(xiàn),被試閉眼執(zhí)行實(shí)驗(yàn)任務(wù)。對(duì)于男性來(lái)說(shuō),運(yùn)動(dòng)執(zhí)行任務(wù)(motor execution,ME)包括4組啞鈴運(yùn)動(dòng)。聽到聲音“1”時(shí),拿起4磅的啞鈴按照隨后呈現(xiàn)的節(jié)奏(1 Hz)進(jìn)行鍛煉;聽到聲音“2”時(shí),拿起8磅的啞鈴按照相同的節(jié)奏進(jìn)行鍛煉,聲音“1”和聲音“2”隨機(jī)呈現(xiàn)。聽到聲音“嘟”時(shí),放下啞鈴,全身放松休息,見圖1。右手完成運(yùn)動(dòng)執(zhí)行任務(wù)。

圖1 實(shí)驗(yàn)流程圖

在運(yùn)動(dòng)想象任務(wù)中,聽到聲音“1”,想象拿起 4磅的啞鈴進(jìn)行鍛煉;聽到聲音“2”,想象拿起8磅的啞鈴進(jìn)行鍛煉;想象右手在做啞鈴運(yùn)動(dòng)。除了上述不一致外,其余都與運(yùn)動(dòng)執(zhí)行任務(wù)一樣。

為了使實(shí)驗(yàn)被試獲得運(yùn)動(dòng)想象的標(biāo)準(zhǔn),所有被試都先完成運(yùn)動(dòng)執(zhí)行任務(wù),再進(jìn)行運(yùn)動(dòng)想象任務(wù)。運(yùn)動(dòng)想象任務(wù)完成后,使用自編《運(yùn)動(dòng)想象自評(píng)問卷》,要求被試評(píng)價(jià)自己完成運(yùn)動(dòng)想象任務(wù)時(shí)的想象品質(zhì)。

對(duì)于女性實(shí)驗(yàn)被試來(lái)說(shuō),除了將8磅啞鈴換成2磅啞鈴之外,其余的實(shí)驗(yàn)程序都同男性。

2.6 探頭布置

使用 4×7的多通道探頭架,包括 14個(gè)發(fā)射器和14個(gè)探測(cè)器,探頭間距為3cm,構(gòu)成45個(gè)通道,覆蓋額葉-頂葉皮層。根據(jù)國(guó)際10-20系統(tǒng),將通道23定位于 Cz上(見圖2,其中紅色為發(fā)射探頭,藍(lán)色為接收探頭)。fNIRS測(cè)試后,使用 3D定位儀(FASTRAK,Polhemus,Colchester,VT,USA)確定Cz、Nz、AL、AR點(diǎn)及探頭位置。通過概率配準(zhǔn)方法將 fNIRS通道位置與 MNI空間坐標(biāo)進(jìn)行配準(zhǔn),獲得與布魯?shù)侣謪^(qū)之間的對(duì)應(yīng)關(guān)系。表2、表3列出的通道定位區(qū)域?yàn)樵撏ǖ栏采w概率最大的區(qū)域。本研究主要觀測(cè)區(qū)域?yàn)橹鬟\(yùn)動(dòng)皮層,但也給出了前運(yùn)動(dòng)皮層和輔助運(yùn)動(dòng)皮層、體感皮層和體感聯(lián)合皮層的對(duì)應(yīng)關(guān)系,見圖3,其中綠色代表主運(yùn)動(dòng)皮層,紅色代表前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層,藍(lán)色代表體感皮層,黃色代表體感聯(lián)合皮層。定位結(jié)果如表2、表3所示。

2.7 數(shù)據(jù)分析

首先,在Matlab (v2014a)操作環(huán)境下使用NIRSSPM (Near infrared Spectroscopy-Statistical Parametric Mapping)軟件(v4.1) (Ye,Tak,Jang,Jung,&Jang,2009)分析fNIRS數(shù)據(jù)。先使用主成分分析方法(Principal Components Analysis,PCA) (Virtanen,Noponen,&Meril?inen,2009;Wilcox,Bortfeld,Woods,Wruck,&Boas,2008)去噪聲。主成分分析是一種簡(jiǎn)化數(shù)據(jù)集的技術(shù),應(yīng)用正交變換將原始的數(shù)據(jù)集分解成N個(gè)相互無(wú)關(guān)聯(lián)的成分。因此可以通過 PCA過濾掉生理噪聲和運(yùn)動(dòng)偽跡。Cooper等(2012)敏感度分析結(jié)果顯示：PCA的閾限值百分?jǐn)?shù)設(shè)置為97%時(shí)其去噪效果達(dá)最佳,故本研究將其設(shè)置為97%。

圖2 fNIRS通道布局

表2 通道布局與布魯?shù)侣謪^(qū)間的對(duì)應(yīng)關(guān)系(男性)

表3 通道布局與布魯?shù)侣謪^(qū)間的對(duì)應(yīng)關(guān)系(女性)

圖3 通道布局與主要觀測(cè)區(qū)域的對(duì)應(yīng)關(guān)系

其次,根據(jù)血液動(dòng)力響應(yīng)函數(shù)(Haemodynamic Response Functions,HRF)和 Wavelet-MDL 方法(Jang et al.,2009)再次排除掉噪聲(頭動(dòng)、心跳等)和漂移。Wavelet-MDL (Wavelet-minimum description length)分析是一種去除信號(hào)漂移的算法,校正因呼吸、被試運(yùn)動(dòng)、機(jī)器熱噪聲等引起的信號(hào)失真。通過小波變換將fNIRS測(cè)量值分解出整體趨勢(shì)、血液動(dòng)力信號(hào)和無(wú)關(guān)噪聲成分。其中MDL原則有利于整體趨勢(shì)評(píng)估最優(yōu)模型的選擇,阻止過分?jǐn)M合或擬合不足的現(xiàn)象發(fā)生。

再次,通過一般線性模型(General Linear Model,GLM)整合任務(wù)效應(yīng),用任務(wù)擬合參考波推斷參數(shù)估計(jì)(GLM模型中beta值的權(quán)重),precoloring方法調(diào)節(jié)此過程的時(shí)間自相關(guān)。最后,在 SPSS的基礎(chǔ)上根據(jù)實(shí)驗(yàn)設(shè)計(jì),分別對(duì)不同運(yùn)動(dòng)任務(wù)下獲得的beta值進(jìn)行單樣本或配對(duì)樣本

t

檢驗(yàn)。使用 FDR(false discovery rate)校正所有的

p

值,校正后

p

＜0.05為顯著(Singh &Dan,2006),對(duì)于沒有進(jìn)行FDR校正的情況,會(huì)在結(jié)果中進(jìn)行說(shuō)明。

3 結(jié)果

3.1 運(yùn)動(dòng)想象自評(píng)問卷

在執(zhí)行完運(yùn)動(dòng)想象任務(wù)后,實(shí)驗(yàn)被試填寫《運(yùn)動(dòng)想象自評(píng)問卷》。其中運(yùn)動(dòng)想象品質(zhì)的評(píng)價(jià)從1“無(wú)法想象”到7“非常容易”;以及對(duì)不同強(qiáng)度運(yùn)動(dòng)想象任務(wù)間差異的評(píng)價(jià),從 1“差異巨大”到 7“沒有差異”。

結(jié)果顯示,男性被試認(rèn)為4磅和8磅啞鈴運(yùn)動(dòng)想象任務(wù)都能較容易的想象出來(lái),評(píng)定分?jǐn)?shù)分別為5.73 (

SD

＝0.80)和5.47 (

SD

＝1.36);在評(píng)定自己完成4磅與8磅啞鈴運(yùn)動(dòng)想象任務(wù)的想象差異時(shí),都認(rèn)為這兩種想象任務(wù)間存在中等以上程度的差異,評(píng)定分?jǐn)?shù)為 3.40(

SD

＝1.30)。女生也能夠較容易地完成2磅和4磅啞鈴運(yùn)動(dòng)想象任務(wù),評(píng)定分?jǐn)?shù)分別為5.73 (

SD

＝0.70)和5.33 (

SD

＝1.23),兩者間差異的評(píng)定分?jǐn)?shù)為3.60 (

SD

＝1.24)。這說(shuō)明被試能夠想象出不同運(yùn)動(dòng)強(qiáng)度下的啞鈴運(yùn)動(dòng)。另外,對(duì)男性、女性在4磅啞鈴運(yùn)動(dòng)想象任務(wù)下的想象品質(zhì)進(jìn)行獨(dú)立樣本

t

檢驗(yàn),結(jié)果顯示男、女性的想象品質(zhì)沒有顯著差異,

t

(28)=1.054,

p

＞0.05。

3.2 運(yùn)動(dòng)執(zhí)行任務(wù)

3.2.1 男性在運(yùn)動(dòng)執(zhí)行任務(wù)下的腦激活情況

對(duì)不同強(qiáng)度的運(yùn)動(dòng)執(zhí)行任務(wù)進(jìn)行單樣本

t

檢驗(yàn),檢驗(yàn)值為0。根據(jù)各通道的

t

值,繪制了熱點(diǎn)圖3。其中執(zhí)行 4磅啞鈴運(yùn)動(dòng)沒被顯著激活的通道包括ch8,ch10,ch11,ch21,ch24,ch33,ch35,ch40,ch41、ch42、ch43,其余通道都被顯著激活,見圖4(a);執(zhí)行8磅啞鈴運(yùn)動(dòng)沒被顯著激活的通道有ch35、ch41、ch43,其余通道都被顯著激活,見圖4(b)。這說(shuō)明4磅啞鈴運(yùn)動(dòng)與 8磅啞鈴運(yùn)動(dòng)的激活模式基本相同,都激活了主運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層、體感皮層、體感聯(lián)合皮層。對(duì)運(yùn)動(dòng)執(zhí)行任務(wù)下8磅與4磅啞鈴運(yùn)動(dòng)各通道的beta值進(jìn)行配對(duì)樣本

t

檢驗(yàn),這兩種運(yùn)動(dòng)強(qiáng)度下不存在顯著差異的通道包括：ch4,ch5,ch9,ch10,ch11,ch16,ch24,ch35,ch41,ch42,ch43,其余通道都顯著激活。結(jié)果見圖4(c)。

圖4 運(yùn)動(dòng)執(zhí)行任務(wù)下大腦各通道激活t值熱量圖(男性)

結(jié)果顯示,8磅啞鈴運(yùn)動(dòng)在相關(guān)運(yùn)動(dòng)皮層上的激活水平顯著高于4磅啞鈴運(yùn)動(dòng)。這說(shuō)明運(yùn)動(dòng)強(qiáng)度影響運(yùn)動(dòng)區(qū)域的激活水平。

3.2.2 女性在運(yùn)動(dòng)執(zhí)行任務(wù)下的腦激活情況

對(duì)運(yùn)動(dòng)執(zhí)行任務(wù)下2和4磅啞鈴運(yùn)動(dòng)進(jìn)行單樣本

t

檢驗(yàn),大腦各通道激活

t

值見圖5。其中執(zhí)行2磅啞鈴運(yùn)動(dòng)沒有顯著激活的通道包括ch8,ch9,ch10,ch12,ch16,ch21,ch22,ch24,ch25,其余通道都被顯著激活,見圖5(a);執(zhí)行4磅啞鈴運(yùn)動(dòng)沒有顯著激活的通道包括 ch9,ch10,ch11,ch12,ch16,ch22,ch24,ch42,其余通道都被顯著激活見圖5(b)。結(jié)果顯示：2磅啞鈴運(yùn)動(dòng)與4磅啞鈴運(yùn)動(dòng)的激活模式類似,也都激活了主運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層、體感皮層、體感聯(lián)合皮層。對(duì)不同強(qiáng)度運(yùn)動(dòng)執(zhí)行任務(wù)下各通道的 beta值進(jìn)行配對(duì)樣本

t

檢驗(yàn),執(zhí)行4磅與2磅啞鈴運(yùn)動(dòng)各通道差異不顯著;不進(jìn)行校正時(shí),存在顯著差異的通道包括：ch1,ch2,ch4,ch5,ch7,ch8,ch14,ch17,ch18,ch19,ch21,ch26,ch29,ch30,ch31,ch33,ch34,ch36,ch40,ch41,ch44,見圖5(c)。這說(shuō)明4磅啞鈴運(yùn)動(dòng)的皮層激活水平高于2磅啞鈴運(yùn)動(dòng),運(yùn)動(dòng)強(qiáng)度也同樣影響運(yùn)動(dòng)執(zhí)行任務(wù)下女性大腦觀測(cè)皮層的激活水平,但這一結(jié)果存在一定的假陽(yáng)性。

圖5 運(yùn)動(dòng)執(zhí)行任務(wù)下大腦各通道激活t值熱量圖(女性)

3.3 運(yùn)動(dòng)想象任務(wù)

3.3.1 男性在運(yùn)動(dòng)想象任務(wù)下的腦激活情況

同樣,對(duì)運(yùn)動(dòng)想象任務(wù)中的4磅和8磅啞鈴運(yùn)動(dòng)想象分別進(jìn)行單樣本

t

檢驗(yàn)和配對(duì)樣本

t

檢驗(yàn)(圖6)。

圖6 運(yùn)動(dòng)想象任務(wù)下大腦各通道激活t值熱量圖(男性)

結(jié)果顯示,4磅啞鈴運(yùn)動(dòng)想象任務(wù)顯著激活的通道包括：ch3,ch15,ch17,ch23,ch28,ch30,ch36。說(shuō)明4磅啞鈴運(yùn)動(dòng)想象任務(wù)激活了主運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層,但不進(jìn)行 FDR校正時(shí),4磅啞鈴運(yùn)動(dòng)想象任務(wù)也會(huì)激活這4個(gè)觀測(cè)區(qū)域。8磅啞鈴運(yùn)動(dòng)想象任務(wù)顯著激活的通道包括：ch3,ch7,ch11,ch15,ch16,ch17,ch18,ch20,ch23,ch27,ch28,ch30,ch32,ch33,ch36,ch37,ch38,ch39,ch40,ch43,ch44,ch45。表明8磅啞鈴運(yùn)動(dòng)想象也激活主運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層、體感皮層、體感聯(lián)合皮層。對(duì)8磅和4磅啞鈴運(yùn)動(dòng)想象任務(wù)進(jìn)行配對(duì)樣本

t

檢驗(yàn),發(fā)現(xiàn)通道間差異不顯著,即這兩種任務(wù)下大腦皮層的激活水平無(wú)顯著差異。想象強(qiáng)度的改變沒有影響到運(yùn)動(dòng)想象任務(wù)下男性大腦皮層的激活水平。

3.3.2 女性在運(yùn)動(dòng)想象任務(wù)下的腦激活情況

對(duì)女性在不同強(qiáng)度的想象任務(wù)下各通道的beta值進(jìn)行

t

檢驗(yàn),發(fā)現(xiàn)2磅啞鈴運(yùn)動(dòng)想象任務(wù)沒有顯著激活的通道包括：ch8,ch10,ch12,ch17,ch21,ch22,ch24,ch34,ch42,其余通道都被顯著激活;4磅啞鈴運(yùn)動(dòng)想象任務(wù)沒有顯著激活的通道包括：ch8,ch10,ch21,ch24,ch25,ch26,ch31,ch34,ch35,ch42,其余通道都被顯著激活。這表明2磅啞鈴運(yùn)動(dòng)想象與4磅啞鈴運(yùn)動(dòng)想象皮層激活模式相似,都激活了4個(gè)觀測(cè)皮層。對(duì)4磅和2磅啞鈴運(yùn)動(dòng)想象任務(wù)進(jìn)行配對(duì)樣本

t

檢驗(yàn),同樣發(fā)現(xiàn)不同強(qiáng)度運(yùn)動(dòng)想象任務(wù)下的皮層激活水平無(wú)顯著差異。詳見圖7。

圖7 運(yùn)動(dòng)想象任務(wù)下大腦各通道激活t值熱量圖(女性)

3.4 運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象皮層激活模式的比較

3.4.1 男生在運(yùn)動(dòng)執(zhí)行任務(wù)與運(yùn)動(dòng)想象任務(wù)下的腦激活模式比較

對(duì)4磅啞鈴運(yùn)動(dòng)與4磅啞鈴運(yùn)動(dòng)想象和8磅啞鈴運(yùn)動(dòng)與8磅啞鈴運(yùn)動(dòng)想象進(jìn)行配對(duì)樣本

t

檢驗(yàn)。結(jié)果顯示在執(zhí)行4磅啞鈴運(yùn)動(dòng)與運(yùn)動(dòng)想象任務(wù)下差異不顯著的通道包括：ch10,ch22,ch24,ch41,ch42,ch43,其余通道都顯著;在執(zhí)行 8磅啞鈴運(yùn)動(dòng)與運(yùn)動(dòng)想象任務(wù)下差異不顯著的通道包括：ch22,ch24,ch35,ch41,ch42,ch43,同樣其余通道都顯著,詳見圖8。可見,無(wú)論運(yùn)動(dòng)強(qiáng)度如何變化,運(yùn)動(dòng)執(zhí)行任務(wù)下觀測(cè)皮層內(nèi)相關(guān)通道的激活水平顯著高于運(yùn)動(dòng)想象任務(wù)下相關(guān)通道的激活水平。

3.4.2 女生在運(yùn)動(dòng)執(zhí)行任務(wù)與運(yùn)動(dòng)想象任務(wù)下的腦激活模式比較

對(duì)2磅啞鈴運(yùn)動(dòng)與2磅啞鈴運(yùn)動(dòng)想象和4磅啞鈴運(yùn)動(dòng)與4磅啞鈴運(yùn)動(dòng)想象進(jìn)行配對(duì)樣本

t

檢驗(yàn)。結(jié)果顯示在2磅啞鈴運(yùn)動(dòng)與運(yùn)動(dòng)想象任務(wù)下差異顯著的通道包括：ch7,ch13,ch14,ch15,ch20,ch27,ch28,ch40;在 4磅啞鈴運(yùn)動(dòng)與運(yùn)動(dòng)想象任務(wù)下差異顯著的通道包括：ch1,ch3,ch4,ch5,ch6,ch7,ch13,ch14,ch15,ch18,ch20,ch23,ch26,ch27,ch28,ch29,ch33,ch34,ch35,ch36,ch39,ch40,ch41,ch43,ch44,ch45。詳見圖9。這表明,對(duì)于女生來(lái)說(shuō),運(yùn)動(dòng)執(zhí)行任務(wù)的腦激活水平顯著高于運(yùn)動(dòng)想象任務(wù)。

3.5 男、女性在運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象任務(wù)下激活優(yōu)勢(shì)腦的分析

本研究對(duì)左右腦通道下的 beta值進(jìn)行配對(duì)樣本

t

檢驗(yàn),以比較男女性在4磅啞鈴運(yùn)動(dòng)與運(yùn)動(dòng)想象下左右腦的激活情況。詳見表4。

圖8 運(yùn)動(dòng)執(zhí)行任務(wù)與運(yùn)動(dòng)想象任務(wù)各通道激活水平的比較(男性)

圖9 運(yùn)動(dòng)執(zhí)行任務(wù)與運(yùn)動(dòng)想象任務(wù)各通道激活水平的比較(女性)

表4 男、女性在不同任務(wù)下左右腦通道差異的比較：t(dcohen)

結(jié)果發(fā)現(xiàn),男性被試在4磅啞鈴運(yùn)動(dòng)下左右半球差異顯著的通道所對(duì)應(yīng)的皮層包括左側(cè)的體感皮層、主運(yùn)動(dòng)皮層、輔助運(yùn)動(dòng)皮層和前運(yùn)動(dòng)皮層,左半球的激活水平強(qiáng)于右半球;女性被試在4磅啞鈴運(yùn)動(dòng)下左右半球差異顯著的區(qū)域包括左側(cè)的體感皮層、體感聯(lián)合皮層、主運(yùn)動(dòng)皮層、輔助運(yùn)動(dòng)皮層和前運(yùn)動(dòng)皮層、緣上回、角回,同樣左腦的激活水平高于右腦?？梢?男性、女性在同等重量的運(yùn)動(dòng)執(zhí)行任務(wù)下左半球皮層的激活情況高于右半球,其中男性主要集中在運(yùn)動(dòng)皮層,而女性表現(xiàn)的更為寬泛。男性和女性在4磅啞鈴運(yùn)動(dòng)想象任務(wù)下左右半球間各通道差異不顯著,這說(shuō)明無(wú)論被試是男性還是女性,在運(yùn)動(dòng)想象任務(wù)下左半球皮層激活情況與右半球皮層激活情況相似,不存在優(yōu)勢(shì)腦。

4 討論

本研究發(fā)現(xiàn)運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象都激活了主運(yùn)動(dòng)皮層;除了男性在想象舉4磅啞鈴任務(wù)下僅激活主運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層和輔助運(yùn)動(dòng)皮層外,其余無(wú)論男性還是女性在運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象任務(wù)下都激活了這4個(gè)探測(cè)皮層,且運(yùn)動(dòng)執(zhí)行的激活水平強(qiáng)于運(yùn)動(dòng)想象。從整體趨勢(shì)上來(lái)看,運(yùn)動(dòng)強(qiáng)度影響運(yùn)動(dòng)執(zhí)行任務(wù)相關(guān)運(yùn)動(dòng)區(qū)域的激活水平,即運(yùn)動(dòng)強(qiáng)度越強(qiáng),激活水平越高;在運(yùn)動(dòng)想象任務(wù)下,不同強(qiáng)度的運(yùn)動(dòng)想象任務(wù)間大腦皮層激活水平無(wú)顯著差異。另外男性和女性在運(yùn)動(dòng)執(zhí)行任務(wù)中的左半球皮層的激活水平都高于右半球皮層,而在運(yùn)動(dòng)想象任務(wù)中沒有表現(xiàn)出這一單側(cè)化現(xiàn)象。

4.1 運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象的大腦皮層激活

早期觀點(diǎn)認(rèn)為運(yùn)動(dòng)系統(tǒng)具有一定的等級(jí),根據(jù)不同大腦區(qū)域的運(yùn)動(dòng)控制功能來(lái)說(shuō)可以分成兩部分：運(yùn)動(dòng)計(jì)劃(前運(yùn)動(dòng)中心)和傳送運(yùn)動(dòng)指令到效應(yīng)器的運(yùn)動(dòng)中心。前運(yùn)動(dòng)中心主要包括一些皮層區(qū)域,即輔助運(yùn)動(dòng)皮層、前運(yùn)動(dòng)皮層、扣帶運(yùn)動(dòng)區(qū)域(Jones,Burton,&Porter,1975),和一些皮層下結(jié)構(gòu),例如紋狀體、小腦等(Yamamoto,Samejima,&Oka,1990)。運(yùn)動(dòng)中心主要指的是主運(yùn)動(dòng)皮層。前運(yùn)動(dòng)中心將運(yùn)動(dòng)執(zhí)行指令發(fā)送給主運(yùn)動(dòng)皮層。主運(yùn)動(dòng)皮層的傳入信息在中央前回的細(xì)胞層中進(jìn)行整合,調(diào)節(jié)該區(qū)域的加熱速度(Yamamoto et al.,1990),繼而將運(yùn)動(dòng)指令傳出到機(jī)體肌肉(Georgopoulos,Ashe,Smyrnis,&Taira,1992)。即主運(yùn)動(dòng)區(qū)的功能在于給效應(yīng)器傳遞運(yùn)動(dòng)指令,更多表現(xiàn)在運(yùn)動(dòng)執(zhí)行上。這一觀點(diǎn)得到部分研究的支持(Binkofski et al.,2000;Hanakawa et al.,2003)。

然而,本研究在運(yùn)動(dòng)執(zhí)行任務(wù)和運(yùn)動(dòng)想象任務(wù)時(shí)都發(fā)現(xiàn)了主運(yùn)動(dòng)區(qū)的激活,與一些研究結(jié)果相一致(Gao,Duan,&Chen,2011;Leonardo et al.,1995;Lotze et al.,1999;Nair,Purcott,Fuchs,Steinberg,&Kelso,2003)。Jones 等(1975)和 Donoghue,Leibovic和Sanes (1992)還發(fā)現(xiàn)中央前回與前運(yùn)動(dòng)中心的皮層或皮層下結(jié)構(gòu)存在復(fù)雜的傳入-傳出關(guān)系。這些研究使傳統(tǒng)觀點(diǎn)面臨巨大的挑戰(zhàn)。

研究者們對(duì)主運(yùn)動(dòng)皮層(BA4)進(jìn)行了細(xì)分,分成了兩部分。接近前運(yùn)動(dòng)皮層與輔助運(yùn)動(dòng)皮層(BA6)的部分為 BA4a區(qū),是運(yùn)動(dòng)想象主要激活的位置;后面部分為BA4p區(qū),與純粹的運(yùn)動(dòng)執(zhí)行關(guān)系密切(Stippich,Ochmann,&Sartor,2002)。換句話說(shuō),無(wú)論主運(yùn)動(dòng)皮層怎樣劃分,其功能也不僅僅局限于運(yùn)動(dòng)執(zhí)行上,主運(yùn)動(dòng)皮層還具有運(yùn)動(dòng)計(jì)劃、運(yùn)動(dòng)控制的功能。

運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象也激活了輔助運(yùn)動(dòng)皮層(SMA)、前運(yùn)動(dòng)皮層(PMC)、體感聯(lián)合皮層等區(qū)域。研究者們(Stephan et al.,1995)認(rèn)為輔助運(yùn)動(dòng)皮層與前運(yùn)動(dòng)皮層在運(yùn)動(dòng)想象中起關(guān)鍵作用,因?yàn)檩o助運(yùn)動(dòng)皮層與運(yùn)動(dòng)計(jì)劃有關(guān)。想象任務(wù)的類型與前運(yùn)動(dòng)皮層的激活位置有關(guān),Binkofski等(2000)發(fā)現(xiàn)視覺想象激活腹側(cè)前運(yùn)動(dòng)皮層,動(dòng)覺想象激活背側(cè)前運(yùn)動(dòng)皮層。Wolbers等(2003)發(fā)現(xiàn)體感聯(lián)合皮層與運(yùn)動(dòng)軌跡有關(guān),本研究的實(shí)驗(yàn)任務(wù)是舉啞鈴,存在空間上的移動(dòng)。雖然各個(gè)區(qū)域都具有一定的功能作用,但具體、清晰的內(nèi)部功能聯(lián)接還需要繼續(xù)挖掘。

4.2 運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象大腦皮層的激活水平

本研究發(fā)現(xiàn),不同強(qiáng)度的運(yùn)動(dòng)執(zhí)行任務(wù)下主運(yùn)動(dòng)皮層的激活水平不同,運(yùn)動(dòng)強(qiáng)度越大,激活水平越高;然而,運(yùn)動(dòng)想象任務(wù)沒有因運(yùn)動(dòng)想象強(qiáng)度的變化而影響皮層激活水平。原因可能是主運(yùn)動(dòng)皮層激活水平的變化是由體覺信息傳入引起的。運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象最主要的差異就是一個(gè)存在、一個(gè)不存在肌肉收縮。在肌肉收縮的這個(gè)過程中,主運(yùn)動(dòng)皮層向運(yùn)動(dòng)神經(jīng)元與體感皮層傳遞運(yùn)動(dòng)指令,使體感皮層接受從肌梭和皮膚感受器上傳入的反饋信號(hào)。在本研究中想象強(qiáng)度與皮層激活水平之間關(guān)系不顯著,可能就是由于缺少外周反應(yīng)的傳入信息導(dǎo)致的(Mizuguchi et al.,2014)。

然而,近期 Mizuguchi,Umehara,Nakata和Kanosue (2013)的研究發(fā)現(xiàn)右手想象力量的加強(qiáng)伴隨著左半球皮層脊髓束興奮性的增強(qiáng)。這說(shuō)明左側(cè)主運(yùn)動(dòng)皮層與想象強(qiáng)度是存在一定關(guān)聯(lián)的。但在Mizuguchi 等(2014)探討前運(yùn)動(dòng)-頂葉區(qū)域與想象強(qiáng)度水平間關(guān)系時(shí),沒有發(fā)現(xiàn)顯著的主運(yùn)動(dòng)皮層激活。本研究在已控制了相關(guān)影響變量(例如被試想象力、任務(wù)類型等)后,雖發(fā)現(xiàn)運(yùn)動(dòng)想象任務(wù)都能夠激活主運(yùn)動(dòng)皮層,但想象強(qiáng)度不影響運(yùn)動(dòng)想象任務(wù)下主運(yùn)動(dòng)皮層的激活水平。

4.3 研究局限與展望

我們推測(cè)運(yùn)動(dòng)強(qiáng)度不影響主運(yùn)動(dòng)皮層激活水平的原因可能是這兩種運(yùn)動(dòng)想象任務(wù)間的想象強(qiáng)度差異不夠大。在《運(yùn)動(dòng)想象自評(píng)問卷》中被試認(rèn)為這兩種強(qiáng)度的運(yùn)動(dòng)想象存在中等以上程度的差異,如果我們?cè)黾酉胂髲?qiáng)度的差異程度,是否能夠引起主運(yùn)動(dòng)皮層的活動(dòng)變化？這是我們進(jìn)一步想要探索的。本研究的另一個(gè)局限是：固定的任務(wù)執(zhí)行順序,即先執(zhí)行運(yùn)動(dòng)執(zhí)行任務(wù),再執(zhí)行運(yùn)動(dòng)想象任務(wù),沒有對(duì)實(shí)驗(yàn)順序效應(yīng)進(jìn)行抵消平衡。我們也將會(huì)在今后研究中對(duì)這一局限進(jìn)行修正。

此外,越來(lái)越多的研究者證明了基于fNIRS的神經(jīng)反饋訓(xùn)練能夠調(diào)節(jié)運(yùn)動(dòng)想象水平(Chiew,LaConte,&Graham,2012;Johnson et al.,2012;Kanoh,Susila,Miyamoto,Yoshinobu,&Kawashima,2011;Mihara et al.,2012)。在接下來(lái)的工作中,我們將會(huì)通過神經(jīng)反饋技術(shù)訓(xùn)練被試對(duì)不同強(qiáng)度的運(yùn)動(dòng)想象任務(wù)的執(zhí)行控制力,以期更為客觀的探究想象強(qiáng)度對(duì)相關(guān)皮層的影響作用。也會(huì)為神經(jīng)修復(fù)領(lǐng)域帶來(lái)一定的實(shí)證價(jià)值。

5 結(jié)論

運(yùn)動(dòng)執(zhí)行與運(yùn)動(dòng)想象都顯著激活主運(yùn)動(dòng)皮層。另外,運(yùn)動(dòng)強(qiáng)度影響運(yùn)動(dòng)執(zhí)行任務(wù)下主運(yùn)動(dòng)皮層的激活水平;運(yùn)動(dòng)想象任務(wù)下主運(yùn)動(dòng)皮層的激活情況不受想象強(qiáng)度的調(diào)節(jié)。

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