Motor Homunculus: Passive Mapping in Healthy Volunteers by Using Functional MR Imaging—Initial Results

Abstract

Purpose:To determine the concurrence of activation in the primary motor cortex, induced by paradigms of active and passive movement of extremities, by using blood oxygen leveldependent functional magnetic resonance (MR) imaging. Materials and Methods:The HIPAA-compliant study was approved by the institutional review board, and written informed consent was obtained from the participating volunteers. Functional MR imaging data were collected from 11 healthy volunteers (four women, seven men; age range, 24 -42 years) during active and passive movements of hand, elbow, shoulder, ankle, knee, and hip. These data were then mapped onto three-dimensional anatomic images. Volumes of activation were determined by using cross-correlation analysis at a coefficient threshold of 0.4 (P Ͻ .01). Regions of interest were drawn in pre-and postcentral gyri based on anatomic criteria. The mean number of activated voxels in the preand postcentral gyri induced by active and passive movements was compared by using Wilcoxon analysis. Concurrence ratios and proportional ratios of activation between active and passive movements were calculated for each somatotopic location.

Variation of stimulation intensity in transcranial magnetic stimulation with depth

“…With intraoperative electrostimulation the majority of positions with positive stimulations scattered between 15 mm and 34 mm of depth below cortex surface on the mesial wall of the hemisphere (Allison et al, 1996). Similarly, functional MRI of ankle movements reveals activations extending down to the cingulate gyrus on the medial surface but also some distance on the convexity of the brain (Kocak et al, 2009;Qazi et al, 2009). …”

Cortical Activation Through Passive-Motion Functional MRI

“…23,24 Additional studies have shown the activation with passive movement to correspond to the location of volitional movement. 30 To our knowledge, this study involves the largest population in the existing literature on this subject. In addition, we demonstrated the ability to use passive-motion fMRI 13 times in patients younger than 2 years, the youngest of whom was 6 months of age.…”

Comparative Functional MRI Study to Assess Brain Activation Upon Active and Passive Finger Movements in Patients with Cerebral Infarction

“…Several studies have shown that active movement, passive movement, and motor imagery activate common neural substrates, such as the motor and premotor cortex [8,9,10,11]. Using fMRI analyses, Lange et al reported that passive finger movements activated similar brain regions as active finger movements [12].…”