Sains Malaysiana 43(2)(2014): 313–319

Ketinggian Pengaktifan Korteks dan Kebergantungan Hemodinamiknya semasa

Tepikan Jari Rentak Sendiri Bilateral Pelbagai Gaya

(Cortical Height Extent of Activation and its Hemodynamic Dependencies during Bilateral Self-paced Finger Tapping of Multiple Styles)

A.N. Yusoff

Program Pengimejan Diagnostik & Radioterapi, Pusat Pengajian Sains Diagnostik & Kesihatan Gunaan, Fakulti Sains Kesihatan, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia

Diserahkan: 31 Disember 2012/Diterima: 15 Mei 2013

ABSTRAK

Kajian pengimejan resonans magnet kefungsian (fMRI) subjek tunggal ini mengkaji hubung kait asas antara parameter hemodinamik dengan ketinggian pengaktifan (nilai t) bagi beberapa korteks berkaitan motor. Dalam kajian ini, subjek melakukan empat gaya tepikan jari rentak sendiri iaitu sentuh-perlahan (SP), sentuh-laju (SL), tekan-perlahan (TP) dan tekan-laju (TL) dalam satu imbasan fMRI. Data fMRI dianalisis menggunakan pemetaan statistik berparameter (SPM). Keputusan analisis mendapati otak mengkoordinasi keempat-empat gaya tepikan dengan penglibatan girus presentral (PCG) bilateral, kawasan motor tambahan (SMA), lobus parietal superior (SPL) dan serebelum. SPL didapati menunjukkan anjakan kelateralan akibat peningkatan laju tepikan. Magnitud pengaktifan pada SPL kiri yang lebih rendah berlaku semasa tepikan perlahan manakala tepikan laju memperlihatkan magnitud pengaktifan yang lebih tinggi pada SPL kanan. Plot nilai t melawan peratus perubahan isyarat bagi kesemua kawasan tersebut untuk kesemua gaya tepikan menunjukkan korelasi positif (p< 0.05, r= 0.67). Nilai t menunjukkan korelasi positif tak bererti terhadap efikasi neuron (p= 0.08, r= 0.40), korelasi positif bererti terhadap pereputan isyarat (p< 0.05, r= 0.85) dan masa transit (p< 0.05, r= 0.88) serta korelasi negatif bererti terhadap suap balik (p< 0.05, r= 0.89). Pemalar kekerasan (α) dan peratus ekstraksi oksigen (E_o) didapati kekal malar untuk kesemua korteks dalam semua cara tepikan. Kajian ini telah mendedahkan maklumat asas berguna mengenai ciri hemodinamik beberapa korteks berkaitan motor yang mengalami pengaktifan.

Kata kunci: Efikasi neuron; masa transit; peratus perubahan isyarat; pereputan isyarat; suap balik

ABSTRACT

This single participant functional magnetic resonance imaging (fMRI) study investigates the fundamental relationship between several hemodynamic parameters and the height extent of activation (t-value) for several motor-related cortices. In this study the participant performed four styles of self-paced hand finger tapping which are soft-slow (SS), soft-fast (SF), hard-slow (HS) and hard-fast (HF) in the fMRI scan. The fMRI data were analysed using statistical parametric mapping (SPM). The analytical results indicated that the brain coordinates all four tapping styles with the involvement of bilateral precentral gyrus (PCG), supplementary motor area (SMA), bilateral superior parietal lobules (SPL) and cerebellum. SPL was found to exhibit laterality shift due to the increase in tapping speed. A lower activation magnitude in the left SPL occurs during slow tapping while fast tapping exhibits higher activation magnitud in the right SPL. The t-values versus percentage of signal change (PSC) plot for all regions and for all tapping styles exhibits positive correlation (p< 0.05, r= 0.67). The t value shows insignificant positive correlation with neuronal efficacy (p= 0.08, r= 0.40), significant positive correlation with signal decay (p< 0.05, r= 0.85) and transit time (p< 0.05, r= 0.88) and significant negative correlation with feedback (p< 0.05, r= 0.89). The stiffness coefficient (α) and the percentage of oxygen extraction (E_o) remain constant for all cortices in all tapping styles. This study has revealed useful fundamental informations on the hemodynamic characteristics of several activated motor related cortices.

Keywords: Feedback; neuronal efficacy, percent signal change, signal decay, transit time

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*Pengarang untuk surat-menyurat; email: nazlim@fsk.ukm.my