Biomedical subjects

Wen-Ching Liu

Publications and source records attributed to Wen-Ching Liu.

9 recordsLinked to original sources

PubMed2005

The effect of tumour type and distance on activation in the motor cortex.

Functional MRI has been widely used to identify the eloquent cortex in neurosurgical/radiosurgical planning and treatment of CNS neoplasms and malformations. In this study we examined the effect of CNS tumours on the blood oxygenation level-dependent (BOLD) activation maps in the primary and supplementary motor cortex. A total of 33 tumour patients and five healthy right-handed adults were enrolled in the study. Patients were divided into four groups based on tumour type and distance from primary motor cortex: (1) intra-axial, near, (2) extra-axial, near, (3) intra-axial, far and (4) extra-axial, far. The intra-axial groups consisted of patients with astrocytomas, glioblastomas and metastatic tumours of mixed histology; all the extra-axial tumours were meningiomas. The motor task was a bilateral, self-paced, finger-tapping paradigm. Anatomical and functional data were acquired with a 1.5 T GE Echospeed scanner. Maps of the motor areas were derived from the BOLD images, using SPM99 software. For each subject we first determined the activation volume in the primary motor area and the supplementary motor area (SMA) and then calculated the percentage difference between the hemispheres. Two factors influenced the activation volumes: tumour type (P<0.04) and distance from the eloquent cortex (P<0.06). Patients in group 1 (intra-axial, near) had the smallest activation area in the primary motor cortex, the greatest percentage difference in the activation volume between the hemispheres, and the largest activation volume in the SMA. Patients in group 4 (extra-axial, far) had the largest activation volume in the primary motor cortex, the least percentage difference in volume between the hemispheres, and the smallest activation volume in the SMA. There was no significant change in the volume of the SMA in any group, compared with controls, suggesting that, although there is a gradual decrease in SMA volume with distance from the primary motor area, the effect on motor reorganisation is minimal. All the tumour patients showed a net loss in total activation volumes (both hemispheres plus SMA) compared with controls. The effect of the tumours on interhemispheric volume differences was: group 1>group 3>group 2>group 4. Within the intra-axial tumours, there was no significant effect of tumour type on the results. We conclude that BOLD-imaged activation volume is affected at least by the interplay of two factors: tumour type and distance from the motor cortex. Further, all tumours may be expected to cause some loss of activation volumes in motor areas. We suggest that, with proper precautions and planning, BOLD functional magnetic resonance imaging (fMRI) maps can be useful in minimising damage to the functional areas.

Adult↗

PubMed2005

Cerebral activation patterns during working memory performance in multiple sclerosis using FMRI.

Working memory deficits are common in Multi Sclerosis (MS) and have been identified behaviourally in numerous studies. Despite recent advance in functional magnetic resonance imaging (fMRI), few published studies have examined cerebral activations associated with working memory dysfunction in MS. The present study examines brain activation patterns during performance of a working memory task in individual with clinically definite MS, compared to healthy controls (HC). fMRI was performed using a 1.5 Tesla GE scanner during a modified Paced Auditory Serial Addition Test (mPA-SAT). Participants were 6 individuals with MS with working memory impairment as evidenced on neuropsychological testing, 5 individuals with MS without working memory impairment, and 5 HC. Groups were demographically equivalent. Data were analyzed using Statistical Parametric Mapping (SPM99) software, with a stringent significance level (alpha < .005, voxel extent > or =8). Both MS groups and the HC group were able to perform the task, with comparable performance in terms of numbers of correct responses. Activation patterns within the HC and MS not-impaired groups were noted in similar brain regions, consistent with published observations in healthy samples That is, activations were lateralized to the left hemisphere, involving predominantly frontal regions. In contrast, the MS impaired group showed greater right frontal and right parietal lobe activation, when compared with the HC group. Thus, it appears that working memory dysfunction in MS is associated with altered patterns of cerebral activation that are related to the presence of cognitive impairement, and not solely a function of MS.

Acoustic Stimulation↗

PubMed2005

Cortical adaptation following partial glossectomy with primary closure: implications for reconstruction of the oral tongue.

OBJECTIVES: The considerable variability in functional outcomes for speech and swallowing with different reconstruction techniques following partial glossectomy may reflect the ability of patients to adapt to altered tongue structure. The purpose of this study was to determine mechanisms of cortical adaptation in swallowing to partial glossectomy reconstructed with primary closure. METHODS: Four patients treated with partial glossectomy and primary closure underwent functional magnetic resonance imaging at a mean of 6 months after operation, and the data were compared to those from 8 healthy controls. RESULTS: Statistically significant increases in activity occurred predominately in the parietal cortices and the cerebellum. The volume of the resection was most highly correlated with activity in the premotor and parietal cortices and cerebellum. CONCLUSIONS: The adaptive changes in the cortex following partial glossectomy with primary closure reflect adaptation to the biomechanics of tongue movement during swallowing, and not altered sensation in the tongue.

Adaptation, Physiological↗

PubMed2004

Brain activation during vaginocervical self-stimulation and orgasm in women with complete spinal cord injury: fMRI evidence of mediation by the vagus nerves.

Women diagnosed with complete spinal cord injury (SCI) at T10 or above report vaginal-cervical perceptual awareness. To test whether the Vagus nerves, which bypass the spinal cord, provide the afferent pathway for this response, we hypothesized that the Nucleus Tractus Solitarii (NTS) region of the medulla oblongata, to which the Vagus nerves project, is activated by vaginal-cervical self-stimulation (CSS) in such women, as visualized by functional magnetic resonance imaging (fMRI). Regional blood oxygen level-dependent (BOLD) signal intensity was imaged during CSS and other motor and sensory procedures, using statistical parametric mapping (SPM) analysis with head motion artifact correction. Physiatric examination and MRI established the location and extent of spinal cord injury. In order to demarcate the NTS, a gustatory stimulus and hand movement were used to activate the superior region of the NTS and the Nucleus Cuneatus adjacent to the inferior region of the NTS, respectively. Each of four women with interruption, or "complete" injury, of the spinal cord (ASIA criteria), and one woman with significant, but "incomplete" SCI, all at or above T10, showed activation of the inferior region of the NTS during CSS. Each woman showed analgesia, measured at the fingers, during CSS, confirming previous findings. Three women experienced orgasm during the CSS. The brain regions that showed activation during the orgasms included hypothalamic paraventricular nucleus, medial amygdala, anterior cingulate, frontal, parietal, and insular cortices, and cerebellum. We conclude that the Vagus nerves provide a spinal cord-bypass pathway for vaginal-cervical sensibility in women with complete spinal cord injury above the level of entry into spinal cord of the known genitospinal nerves.

Adult↗

PubMed2004

fMRI study of acupuncture-induced periaqueductal gray activity in humans.

BOLD fMRI was used to study acupuncture-induced activation (increase in the BOLD signal from undetectable) of the periaqueductal gray (PAG) and two somatosensory cortical areas in seven healthy human subjects. Mechanical stimulation (push-pull) was given to the LI4 (Hoku) acupoint or to a non-acupoint. The stimulation paradigm consisted of 5 runs, each consisting of four 30 s On/30 s OFF periods over 30 min. The scan for each ON period was analyzed individually. The PAG and cortical areas showed different activity patterns. PAG activity was episodic and reliably demonstrated after 20-25 min of stimulation; both cortical areas, however, were active > 90% of the time. Stimulation of a non-acupoint (leg) resulted in reduced levels of PAG and cortical activity.

Acupressure↗

PubMed2004

Differential cerebellar activation on functional magnetic resonance imaging during working memory performance in persons with multiple sclerosis.

OBJECTIVE: To explore the potential role of the cerebellum in working memory dysfunction in multiple sclerosis (MS). DESIGN: Blood oxygen level dependent functional magnetic resonance imaging (fMRI) was used to examine cerebellar activation during a working memory task. SETTING: University-affiliated medical rehabilitation facility. PARTICIPANTS: Eight persons with MS and 5 healthy controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Change in hemodynamic response. fMRI data were acquired and subsequently analyzed by using Statistical Parametric Mapping. RESULTS: Both the control and MS groups showed significantly greater activations in the right cerebellar hemisphere as compared with the left side. Persons with MS, however, showed no detectable activations in 4 cerebellar substructures that were significantly active in controls (ie, right vermis, right dentate nucleus, right tonsil, cerebellar peduncle). CONCLUSIONS: The significantly decreased cerebellar activation in the MS group suggests that the cerebellum may play a role in the working memory impairment observed in MS.

Adolescent↗

PubMed2004

Functional imaging of pain in patients with primary fibromyalgia.

OBJECTIVE: To examine the function of the nociceptive system in patients with fibromyalgia (FM) using functional magnetic resonance imaging (fMRI). METHODS: Two groups of women, 9 with FM and 9 pain-free, volunteered to participate. In Experiment 1, we assessed psychophysical responses to painful stimuli and prepared participants for fMRI testing. For Experiment 2, subjects underwent fMRI scanning while receiving painful and nonpainful heat stimuli. Conventional and functional MR images were acquired using a 1.5 T MR scanner. Scanning occurred over 5 conditions. Condition 1 served as a practice session (no stimuli). Conditions 2 and 5 consisted of nonpainful warm stimuli. Conditions 3 and 4 consisted of an absolute thermal pain stimulus (47 degrees C) and a perceptually equivalent pain stimulus delivered in counterbalanced order. RESULTS: Experiment 1 indicated that subjects with FM were significantly more sensitive to experimental heat pain than controls (p < 0.001). In Experiment 2, fMRI data indicated that the FM group exhibited greater activity than controls over multiple brain regions in response to both nonpainful and painful stimuli (p < 0.01). Specifically, in response to nonpainful warm stimuli, FM subjects had significantly greater activity than controls in prefrontal, supplemental motor, insular, and anterior cingulate cortices (p < 0.01). In response to painful stimuli, FM subjects had greater activity in the contralateral insular cortex (p < 0.01). Data from the practice session indicated brain activity in pain-relevant areas for the FM group but not for controls. CONCLUSION: Our results provide further evidence for a physiological explanation for FM pain.

Adult↗

PubMed2002

Functional localization of brainstem and cervical spinal cord nuclei in humans with fMRI.

BACKGROUND AND PURPOSE: To our knowledge, no published functional map of the human lower brainstem exists. Our purpose was to use 1.5-T functional MR imaging (fMRI) to visualize the location of cranial nerve (CN) nuclei and other pontine, bulbar, and cervical spinal cord nuclei by using specific sensory stimulation or motor performance. METHODS: We localized nuclei by using cross-correlation analysis of regional blood oxygen level-dependent (BOLD) signal intensity during specific motor and sensory procedures based on known functions of specific nuclei. Statistical parametric mapping (SPM) analysis was used for comparison. Head, cardiac, and respiratory motion artifact correction was applied. Histologic atlases aided localization. RESULTS: We obtained evidence of localization of the following nuclei by using tests, as follows: main trigeminal sensory (CN V), brushing the face; abducens (CN VI), left-right eye movement; facial (CN VII), smiling and lip puckering; hypoglossal (CN XII), pushing the tongue against the hard palate; nucleus ambiguus, swallowing; nucleus tractus solitarii (NTS), tasting a sweet-sour-salty-bitter mixture; nucleus cuneatus, finger tapping; and cervical spinal cord levels C1-C3, tongue movement to activate the strap muscles. Activation of cortical motor and sensory areas and somatosensory thalamus corresponded with the tasks and sites of brainstem activation. Head movement was minimal, typically less than 1 mm in all three axes. CONCLUSION: With 1.5-T fMRI, the CN nuclei of the pons and medulla, and other nuclei of the lower brainstem and cervical spinal cord, can be localized in awake humans with specific sensory stimulation or motor performance.

Abducens Nerve↗

PubMedDate not supplied

Translocation of Broca's area to the contralateral hemisphere as the result of the growth of a left inferior frontal glioma.

We report a case of a patient with a left inferior frontal glioma in whom language functional magnetic resonance imaging (fMRI) paradigms produced activation of Broca's area on the right and Wernicke's area on the left. We propose that tumor invasion of the left frontal operculum led to cortical reorganization and interhemispheric transfer of Broca's area. This case emphasizes the importance of preoperative fMRI in assessing the location of eloquent cortices adjacent to a tumor and in guiding neurosurgical decision-making.

Adult↗