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Biomedical subjects

C M Feng

Publications and source records attributed to C M Feng.

14 recordsLinked to original sources
PubMed2001

Neural correlates of response inhibition for behavioral regulation in humans assessed by functional magnetic resonance imaging.

To identify the specific frontal and cingulate regions involved in response inhibition, five Chinese right-handed male volunteers with an attention span reaching or exceeding a 7-digit level participated in this blocked design functional magnetic resonance imaging study. Each block represented one of the two experimental conditions, the Correct Matching or the Incorrect Matching condition. In the Correct Matching condition, the subjects were required to make correct judgement of whether the two 3-digit numbers presented in succession were the same or not; whereas in the Incorrect Matching condition, the participants were instructed to inhibit the correct responses. Bilateral activations of the prefrontal and anterior cingulate as well as the left posterior cingulated cortex were observed while the subjects were exercising response inhibition. The roles of these activations in response inhibition were discussed.

Adult↗
PubMed2001

An fMRI study with written Chinese.

Event-related functional magnetic resonance imaging (ER-fMRI) was used to investigate how the human brain processes phonology and transforms a word's visual form (orthography) into phonological form during reading in logographic Chinese, a writing system that differs markedly from alphabetic languages. We found that reading aloud of irregular words produced larger MR signal intensity changes over extensive regions involving left infero-middle frontal cortex, left motor cortex, right infero-frontal gyri, bilateral anterior superior temporal areas, and anterior cingulate cortex. Right superior parietal lobule, the cuneus in bilateral visual cortex, and thalamus participated in the processing of irregular, but not regular, words. These findings were discussed in comparison to neuroimaging findings from alphabetic languages, as well as in relation to models of reading.

Adult↗
PubMed2001

Perfusion-weighted imaging of interictal hypoperfusion in temporal lobe epilepsy using FAIR-HASTE: comparison with H(2)(15)O PET measurements.

To detect perfusion abnormalities in areas of high magnetic susceptibility in the brain, an arterial spin-labeling MRI technique utilizing flow-sensitive alternating inversion recovery (FAIR) and half-Fourier single shot turbo spin-echo (HASTE) for spin preparation and image acquisition, respectively, was developed. It was initially tested in a functional study involving visual stimulation, and was able to detect significant activation with an increase (approximately 70%) in relative cerebral blood flow. Subsequently, it was applied in a clinical situation in eight patients with temporal lobe epilepsy (TLE). The perfusion-weighted images obtained showed no susceptibility artifacts even in the region of the inferior temporal lobe and were able to detect interictal hypoperfusion in TLE. The results were compared with those derived from H(2)(15)O PET perfusion imaging in each patient. A statistically significant correlation (r = 0.75, P < 0.05) was found between results acquired from these two modalities. Magn Reson Med 45:431-435, 2001.

Artifacts↗
PubMed2001

Cerebral hemodynamic response in Chinese (first) and English (second) language processing revealed by event-related functional MRI.

Comparative functional neuroimaging studies using the block design paradigm have previously demonstrated that there are no significant differences in the location of areas of cerebral activation when native Chinese speakers independently process single words or sentences in both the Chinese (first) and English (second) languages. While it has also been documented that significant domains of brain response include the inferior to middle left frontal lobe, the latency, amplitude and duration of the associated hemodynamic changes during isolated neural processing of Chinese and English languages still remain unknown. The aim of this study, therefore, was to examine the characteristics of the hemodynamic alterations in the above-mentioned regions with event-related functional MRI (ER-fMRI) when native Chinese speakers performed verb generation tasks in both the Chinese (first) and English (second) languages. Our results demonstrate the presence of a similar neural activity-induced hemodynamic response in the inferior to middle left frontal lobe during both tasks. Further, there were also no statistically significant differences among the variables that described the hemodynamic response curves. These findings strongly imply that the underlying neural mechanism for Chinese (first) and English (second) language processing may be similar in native Chinese speakers.

Adult↗
PubMed1994

[Factors of graft failure after chemical corneal injury].

83 cases (97 eyes) of keratoplasty after chemical corneal injury were followed up for a mean 14 months with the results that 21 (21.6%) grafts were transparent and 76 (78.4%) opaque or semitransparent. The success rate depended on the severity of the chemical injury; it was 87.5% for type A corneal scarring and 15.7% for type B. The causes of graft failure were postoperative epithelial erosion (70.7%) and corneal rejection (28.0%). Most patients with epithelial erosion had problems of insufficient tear secretion and tear-film defects. The prevention and management of graft failure were discussed.

Adolescent↗
PubMed1994

[Penetrating keratoplasty in the treatment of corneal perforation].

166 patients of corneal perforation from HSK, suppurative corneal ulcer and chemical or thermal burn were treated by penetrating keratoplasty. In the group of HSK, 69.8% of the grafts remained transparent and vision was restored to 0.05-1.0 in 81 cases (69.8); in the group of suppurative corneal ulcer, 40% of the grafts were transparent and vision was restored to 0.05 or better in 15 cases (37.5%); while in the group of burns, the grafts were clear only in 20% and vision was 0.05-0.6 in 3 cases (30%). The complications and causes for failure were similar to those in patients without perforation. These results indicate that timely penetrating keratoplasty is recommendable for the treatment of corneal perforations of various etiology.

Adolescent↗
PubMed1990

[The causes of blindness by corneal diseases in 3,499 cases].

The chief causes of corneal blindness was found to be corneal inflammatory diseases and injury in 83.4% of the 3,499 cases (3,993 eyes) of corneal blindness that presented themselves during 1983-1985 at the authors' hospital. The important diseases in order of frequency were herpes simplex keratitis (42.8%), bacterial keratitis (17.4%), corneal injuries (15.7%), keratomalacia (10.0%), and trachoma (3.8%). Patients of the latter two diseases were mostly old cases. The authors discussed the incidence of corneal diseases and their prevention and treatment.

Adolescent↗
PubMed1989

[Infections in the early postoperative period following keratoplasty--a report of seven cases].

Keratoplasty was performed on 3482 eyes from 1965 to 1986 in our hospital. Five eyes (0.14%) were infected in the early postoperative period. Two eyes had endophthalmitis. These seven eyes were operated on again and with local and systemic antibiotics treated as well. Followed up for 36 days to 7 years, six eyes remained safe (5 eyes transparent and 1 eye semi-transparent.) The visual acuity reached 0.3 in two eyes, 0.2 in one eye and finger counting to 0.1 in three eyes. The seventh eye was enucleated because of serious infection. Several factors of infection in the early postoperative period following keratoplasty, causative organisms, the relations between the types of operation in the early postoperative period following keratoplasty were also discussed.

Adolescent↗
PubMedDate not supplied

Comparison of the experimental BOLD signal change in event-related fMRI with the balloon model.

Event-related functional MRI (ER-fMRI) based on both blood oxygenation level-dependent (BOLD) contrast and cerebral blood flow (CBF) contrast has been developed to study the human brain response to transient stimulation. A balloon model has been developed and used in understanding the relationship between changes in CBF and in the BOLD signal in block-designed fMRI. In this report, the balloon model was used to interpret experimental event-related fMRI. Using experimental data acquired from CBF-based ER-fMRI as an input function in the balloon model, simulated BOLD signal changes were obtained. The simulated time course of the BOLD signal changes was directly compared with the experimentally acquired data. A chi-square (chi(2)) test showed excellent correlation between the simulated and experimental data (alpha <or= 0.05). Our results have demonstrated that the balloon model is useful in interpreting the transient features of the experimental data from the ER-fMRI studies.

Cerebrovascular Circulation↗