Early detection of cognitive decline in Alzheimer’s disease using eye tracking

BackgroundPatients with Alzheimer’s disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We investigated whether the pattern of gaze exploration during visual tasks could be useful for detecting cognitive decline at the earliest stage.MethodsSixteen AD patients (age: 79.1 ± 7.9 years, Mini Mental State Examination [MMSE] score: 17.7 ± 5.3, mean ± standard deviation) and 16 control subjects (age: 79.4 ± 4.6, MMSE score: 26.9 ± 2.4) participated. In the visual memory task, subjects memorized presented line drawings for later recall. In the visual search tasks, they searched for a target Landolt ring of specific orientation (serial search task) or color (pop-out task) embedded among arrays of distractors. Using video-oculography, saccade parameters, patterns of gaze exploration, and pupil size change during task performance were recorded and compared between AD and control subjects.ResultsIn the visual memory task, the number of informative regions of interest (ROIs) fixated was significantly reduced in AD patients compared to control subjects. In the visual search task, AD patients took a significantly longer time and more saccades to detect the target in the serial but not in pop-out search. In both tasks, there was no significant difference in the saccade frequency and amplitude between groups. On-task pupil modulation during the serial search task was decreased in AD. The number of ROIs fixated in the visual memory task and search time and saccade numbers in the serial search task differentiated both groups of subjects with high sensitivity, whereas saccade parameters of pupil size modulation were effective in confirming normal cognition from cognitive decline with high specificity.DiscussionReduced fixation on informative ROIs reflected impaired attentional allocation. Increased search time and saccade numbers in the visual search task indicated inefficient visual processing. Decreased on-task pupil size during visual search suggested decreased pupil modulation with cognitive load in AD patients, reflecting impaired function of the locus coeruleus. When patients perform the combination of these tasks to visualize multiple aspects of visuospatial processing, cognitive decline can be detected at an early stage with high sensitivity and specificity and its progression be evaluated

Step frequency radar for the measurement of sea ice thickness

The preliminary experiments have been carried out to test the fundamental functions of the step frequency radar. This radar aims at measuring the thickness of the Antarctic sea ice, which transmit 32 different frequencies in a stepwise fashion between 300 and 796MHz. The radar has the following details; a) the maximum transmitting power : 400mW, b) the range resolution : about 0.3m in the air, c) the maximum observable distance without an ambiguity; about 9.1m in the air, and d) the transmitting and receiving antennas : two cavitybacked spiral antennas whose sense of circular polarization is mutually opposite. The experiments in the anechoic chamber have proved that this radar system could have successfully detected the iron pipe buried in the dry sand and the aluminum plate placed under the sand box. This result suggests that with this radar system an airborne survey of the sea ice thickness will become possible

Short treatment time and excellent treatment outcome in accelerated hyperfractionated radiotherapy for T1 glottic cancer

Accelerated hyperfractionated radiotherapy was performed as treatment for patients with T1 glottic cancer, and its utility was evaluated based on treatment outcomes and adverse effects. Fifty-eight men who had undergone radiotherapy were retrospectively reviewed. Tumor classification was Tis in 4 patients, T1a in 38, and T1b in 16. Histological examination revealed squamous cell carcinoma in 55 patients. Travel time from home to hospital was 0–1 hour for 24 patients, 1–2 hours for 9, and >2 hours for 25. Laser vaporization was performed prior to radiotherapy in 38 patients, and 19 patients received concurrent chemotherapy with an agent such as S-1. Patients were irradiated twice daily using an irradiation container. Most patients received a dose of 1.5 Gy/fraction up to a total of 60 Gy. The median overall treatment time was 30 days, with a median observation period of 59.6 months. A complete response was observed in all patients. The 5-year overall survival, disease-free survival, and local control rates were 97.2%, 93.2%, and 97.8%, respectively. Although grade 3 pharyngeal mucositis was observed in 2 patients, there were no other grade 3 or higher acute adverse events. As late toxicity, grade 2 laryngeal edema and grade 1 laryngeal hemorrhage were observed in 1 patient each, but no serious events such as laryngeal necrosis or laryngeal stenosis were observed. In conclusion, this treatment method brings excellent outcome and will substantially reduce the treatment duration among patients who need to stay at nearby hotels while undergoing treatment at hospitals in rural areas

Budd-Chiari Syndrome: Two Cases with Different Courses

We report two cases of Budd-Chiari syndrome. Case 1: A 57-year-old man presented with leg edema and esophageal varices. Cavography showed obstruction of the inferior vena cava with antiphospholipid syndrome. Further, the patient showed positive serology for hepatitis C virus and consumed large quantities of alcohol. Percutaneous transluminal angioplasty was performed on this patient and anticoagulants administered; leg edema and esophageal varices were ameliorated although liver biopsy showed cirrhosis without evident congestion. More than 9 months since the diagnosis, restenosis of the inferior vena cava has not occurred. Case 2: A 73-year-old woman presented abdominal pain but no edema or varices. Cavography showed membranous obstruction of the inferior vena cava which required no therapy. Manifestation of portal hypertension was not present and liver function was maintained although liver biopsy showed obvious congestion. These cases showed untypical features against histopathology, and careful observation will be required for emergence of hepatocellular carcinoma