Research ReportLocation of the corticospinal tract at the corona radiata in human brain
Introduction
The corticospinal tract (CST) is the most important motor pathway in the human brain. Therefore, elucidating the state of the CST is mandatory for the rehabilitation of patients with weakness following brain injury. In the past, many studies have attempted to elucidate the location of the CST in the human brain using post-mortem dissection, electrophysiological, or clinico-radiologic correlation methods (Bertrand et al., 1965, Hanaway and Young, 1977, Kim and Pope, 2005, Kretschmann, 1988, Ross, 1980, Song, 2007). However, these methods have significant limitations in that they cannot visualize or identify the CST in the live brain. By contrast, diffusion tensor tractography (DTT), which is derived from diffusion tensor imaging (DTI), allows the visualization and localization of neural tracts at the subcortical level in three dimensions. Several DTT studies have been published on this topic (Holodny et al., 2005, Ino et al., 2007, Westerhausen et al., 2007, Yamada et al., 2007). However, DTT can lead to erroneous results due to operator-dependent bias that might occur during manual analysis (Lee et al., 2005). To overcome this limitation, some researchers have used the activation of functional MRI for analysis of DTT as a region of interest (ROI) instead of manually selecting an ROI (Guye et al., 2003, Kim et al., 2008). This suggests that DTT analyzed in conjunction with the results of fMRI activation would provide a more accurate localization of the CST.
Among the several regions through which the CST passes, the corona radiata (CR) is important because it is an area that is commonly affected by stroke, and its involvement is related to poor motor outcome in stroke patients (Kwon et al., 2007, Shelton and Reding, 2001). After the initial introduction of DTT, only a single DTT study has been conducted to determine the location of the CST in the CR, and there has been no combined fMRI and DTT study on this topic (Yamada et al., 2007). In the current study, we attempted to elucidate the location of the CST for the hand at the CR in the normal human brain using a combined fMRI/DTT method. To determine the locations of the individual CSTs in the CR, the CSTs are needed to be spatially normalized into a standard anatomical reference space by coregistering them with a standard anatomical template such as Montreal Neurological Institute (MNI) EPI template. However, the normalization is not easy to be applied in the clinical sites. Therefore, we defined the relative coordinates system by using anatomical landmarks as described in the Experimental procedures section for the easiness of clinical application. The locations of CSTs at CR were presented as a probabilistic map in the relative coordinates systems.
Section snippets
Results
The probabilistic functional activation maps for left hand and right hand movements are shown in Figs. 1A and B in order. Because we were interested in the activation in the primary sensori-motor cortex in which the pixels were anticipated to have high probabilities other activated areas with probability less than or equal to 10% were eliminated in the Fig. 1 for better visualization. The activated areas in the left and right hemispheres successfully located in the primary sensori-motor cortex
Discussion
In the current study we investigated the location of the hand CST at the right CR. This approach can be applied in a clinical setting, by analyzing DTT in conjunction with fMRI activation results. It is well-known that there is a somatotopical anterior-to-posterior arrangement of the CST in the CR (Inoue et al., 2001, Kim and Pope, 2005, Song, 2007, Tohgi et al., 1996, Yamada et al., 2007). Recently, Yamada et al. (Yamada et al., 2007), conducted a DTT study to evaluate the location of the CST
Subjects
Sixteen right-handed normal volunteers (14 men, 2 women, mean age = 28 years, range 24–33 years) with no history of neurological disorder were included in this study. All subjects provided signed, informed consent prior to the commencement of the study, and our institutional review board approved the study protocol.
Data acquisition
All data were acquired on a 1.5 T scanner (Hoffman-LaRoche, Ltd, Best, The Netherlands) using a Synergy-L Sensitivity Encoding (SENSE) head coil. The fMRI data were acquired using a
Acknowledgment
This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD)KRF-2005-003-H00026.
References (19)
- et al.
Probabilistic diffusion tractography with multiple fibre orientations: what can we gain?
Neuroimage
(2007) - et al.
Combined functional MRI and tractography to demonstrate the connectivity of the human primary motor cortex in vivo
Neuroimage
(2003) - et al.
Localization of the pyramidal tract in the internal capsule of man
J. Neurol. Sci.
(1977) - et al.
Differences of cortical activation pattern between cortical and corona radiata infarct
Neurosci. Lett.
(2007) - et al.
Corticospinal tract asymmetries at the level of the internal capsule: is there an association with handedness?
Neuroimage
(2007) - et al.
Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging
Nat. Neurosci.
(2003) - et al.
Electrical exploration of the internal capsule and neighbouring structures during stereotaxic procedures
J. Neurosurg.
(1965) - et al.
Diffusion-tensor MR tractography of somatotopic organization of corticospinal tracts in the internal capsule: initial anatomic results in contradistinction to prior reports
Radiology
(2005) - et al.
Somatotopy of corticospinal tract in the internal capsule shown by functional MRI and diffusion tensor images
Neuroreport
(2007)
Cited by (48)
Sensorimotor white matter projections and disease severity in primary Restless Legs Syndrome/Willis-Ekbom disease: a multimodal DTI analysis
2020, Sleep MedicineCitation Excerpt :However, the fact that we did not find any involvement of the posterior corona radiata in mild RLS/WED indicates that the AD decrease might be a result of the disease progress. The corona radiata consists of a mixture of associative and projection tracts and its posterior part is known to include descending pathways, such as the CST [115–117], but thalamocortical fibers from somatosensory nuclei also make a large contribution [90]. Therefore, this result points to possible changes in sensorimotor integration [38–40] underlying the syndrome.
Multiple Subcortical Infarcts Manifested as Isolated Bilateral Palsy of the Hypoglossal Nerve
2018, Journal of Stroke and Cerebrovascular DiseasesCitation Excerpt :Of note, the occurrence of bilateral corona radiata infarcts is very rare, and in previous studies, only 1.2%-1.6% of patients were presented with first-ever stroke in this location.6,7 Furthermore, it is well known that pyramidal tract fibers are somatotopically arranged in the human corona radiata and corticobulbar and corticospinal tracts are located from an anterior to posterior direction.8-10 However, little is known about the location of the corticolingual tract (also referred to as cortico-hypoglossal) at this level.
Pathways of the inferior frontal occipital fasciculus in overt speech and reading
2017, NeuroscienceCitation Excerpt :The corona radiata is connected to the cortical spinal tract, passing through the basal ganglia structures, and the posterior limb of the internal capsule (Wang et al., 2014). This tract is reported to play a role in various gross motor functions, particularly with respect to limb movement (Han et al., 2010). Given evidence for the disruption of fine motor speech processes when gross motor hand movements are required (Hirschfeld and Zwitserlood, 2012), our results showing that increases in FA of the right corona radiata are associated with slower response times, may be a reflection of the specialization and subsequent interference that occurs between gross and fine motor movements.
Improved nTMS- and DTI-derived CST tractography through anatomical ROI seeding on anterior pontine level compared to internal capsule
2015, NeuroImage: ClinicalCitation Excerpt :There is, however, little consensus where — along the course of the CST — to place a second ROI. Two alternative positions have been suggested, one at the level of the internal capsule (posterior limb; Han et al., 2010; Holodny et al., 2005a and 2005b; Pan et al., 2012) and the other at the level of the brain stem (usually midbrain) (Gerardin et al., 2003; Lazar et al., 2003; Nimsky et al., 2006; Frey et al., 2012). However, thus far, it remains unknown which of the two positions yield more accurate tracking results in brain tumour patients.
Preoperative diffusion tensor imaging: Improving neurosurgical outcomes in brain tumor patients
2014, Neuroimaging Clinics of North AmericaCitation Excerpt :A unique characteristic of fiber tracking is the potential of distinguishing specific functional white matter tracts running in the same bundle.37,46,47 The goal here is to increase specificity of DTI data in establishing critical spatial relationships.48 In clinical settings, fiber tracking has been shown to distinguish specific white matter tracts adjacent to brain tumors.49–51
- 1
Fax: + 82 33 760 2562.