Executive dysfunction in patients with spinocerebellar ataxia type 3.

The aim of this study was to assess the cognitive functions of patients with spinocerebellar ataxia type 3(SCA3). We examined 15 patients with genetically confirmed SCA3 and 15 healthy control subjects matched for age, years of education, and intellectual ability. We administered verbal memory (word recall and word recognition) and executive function tasks (word fluency test, forward and backward digit and visual span tests, Kana Pick-out Test, Trail Making Test, and conflicting instructions and a Go/NoGo task from the Frontal Assessment Battery). We found that patients with SCA3 had significantly lower scores than the healthy control subjects on the word recall, semantic, and letter fluency, and backward digit span tests, while word recognition was well preserved. The other executive function tests showed preserved functions in the SCA3 group, indicating that visual working memory, and attention and inhibition control were not affected. The patients with SCA3 showed impaired word recall and intact word recognition, and accordingly, episodic memory encoding and storage processes in short-term memory were preserved. In category and letter-fluency tests, impairment was attributable to word-retrieval from semantic memory. Impaired verbal working memory may be involved in the retrieval of verbal information from phonological storage by means of continuous subvocal rehearsal, rather than a deficit in initial phonological encoding. Essential executive dysfunction in patients with SCA3 may be due to damage in the cerebellar cortex-ventral dentate nucleus-thalamus-prefrontal cortex circuits, which are involved in strategic retrieval of verbal information from different modes of memory storage.

Cognitive dysfunction in patients with spinocerebellar ataxia type 6.

The aim of this study was to assess the cognitive functions of patients with spinocerebellar ataxia type 6 (SCA6). We examined 13 patients with genetically confirmed SCA6 and 13 healthy control subjects matched for age, years of education, global cognitive status, and intellectual ability. We administered verbal memory (word recall and word recognition), executive function (digit span, category and letter fluency, Frontal Assessment Battery, and Trail Making Test-A and B), and visuospatial construction (figure copying) tests. We found that the patients with SCA6 had significantly lower scores on the demanding word recall and letter fluency tests compared to the control subjects, while word recognition was well preserved in the patients with SCA6. The other executive functions tested, as well as visuospatial construction, were preserved in the SCA6 group. However, although memory encoding and storage processes were preserved, the retrieval of memorized information concerning frontal function might be selectively affected in patients with SCA6 compared to in control subjects. The impaired word recall and letter fluency noted in patients with SCA6 were interpreted as being related to a word-retrieval disability. Such dysfunctions may be attributed to damage in the frontal-cerebellum circuit owing to SCA6.

A case of pure autotopagnosia following Creutzfeldt-Jakob disease.

A 69-year-old male (N.A.) with Creutzfeldt-Jakob disease showed pure autotopagnosia. We administered tests evaluating his ability to name his own body parts, to point to body parts (his own and examiner's), and to recognize positional relationships between his body parts by verbal questions and responses. We found impaired localization of the patient's own body parts by pointing and impaired recognition of positional relationships between his body parts. However, there was no impairment in naming his own body parts or in localizing the examiner's body parts. The results suggest a pure autotopagnosia in N.A. leading to an impairment of recognition of the spatial position of his body parts in a three-dimensional body representation within the egocentric reference frame. We were able to rule out the possibility that his pattern of performance could have been due to a disability in programming reaching movements of the arm.

SENJU: a new time-of-flight single-crystal neutron diffractometer at J-PARC.

SENJU is a new single-crystal time-of-flight neutron diffractometer installed at BL18 at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). The diffractometer was designed for precise crystal and magnetic structure analyses under multiple extreme sample environments such as low temperature, high pressure and high magnetic field, and for diffraction measurements of small single crystals down to 0.1 mm3 in volume. SENJU comprises three choppers, an elliptical shape straight supermirror guide, a vacuum sample chamber and 37 scintillator area detectors. The moderator-to-sample distance is 34.8 m, and the sample-to-detector distance is 800 mm. The wavelength of incident neutrons is 0.4-4.4 Š(first frame). Because short-wavelength neutrons are available and the large solid angle around the sample position is covered by the area detectors, a large reciprocal space can be simultaneously measured. Furthermore, the vacuum sample chamber and collimator have been designed to produce a very low background level. Thus, the measurement of a small single crystal is possible. As sample environment devices, a newly developed cryostat with a two-axis (ω and φ axes) goniometer and some extreme environment devices, e.g. a vertical-field magnet, high-temperature furnace and high-pressure cell, are available. The structure analysis of a sub-millimetre size (0.1 mm3) single organic crystal, taurine, and a magnetic structure analysis of the antiferromagnetic phase of MnF2 have been performed. These results demonstrate that SENJU can be a powerful tool to promote materials science research.

Writing errors as a result of frontal dysfunction in Japanese patients with amyotrophic lateral sclerosis.

Loss of communication is a critical problem for advanced amyotrophic lateral sclerosis (ALS) patients. This loss of communication is mainly caused by severe dysarthria and disability of the dominant hand. However, reports show that about 50% of ALS patients have mild cognitive dysfunction, and there are a considerable number of case reports on Japanese ALS patients with agraphia. To clarify writing disabilities in non-demented ALS patients, eighteen non-demented ALS patients and 16 controls without neurological disorders were examined for frontal cognitive function and writing ability. To assess writing errors statistically, we scored them on their composition ability with the original writing error index (WEI). The ALS and control groups did not differ significantly with regard to age, years of education, or general cognitive level. Two patients could not write a letter because of disability of the dominant hand. The WEI and results of picture arrangement tests indicated significant impairment in the ALS patients. Auditory comprehension (Western Aphasia Battery; WAB IIC) and kanji dictation also showed mild impairment. Patients' writing errors consisted of both syntactic and letter-writing mistakes. Omission, substitution, displacement, and inappropriate placement of the phonic marks of kana were observed; these features have often been reported in Japanese patients with agraphia resulted from a frontal lobe lesion. The most frequent type of error was an omission of kana, the next most common was a missing subject. Writing errors might be a specific deficit for some non-demented ALS patients.

Pure topographical disorientation following a right forceps major of the splenium lesion: a case study.

A 72-year-old man with pure topographical disorientation following a focal hemorrhage in the right forceps major of splenium was assessed at 2 weeks and 3 months after the onset. Initially, he could identify familiar buildings and landmarks, but noted topographical disorientation, dysfunction in sense of quarters, and in visuo-spatial function. The improvement of topographical disorientation was attained in 3 months, while the inability of the sense of quarters and manipulating visuo-spatial information remained unchanged. These results suggested the heading disorientation was accompanied with impaired sense of quarters, although disabled sense of quarters continued beyond the recovery of heading disorientation.

The writing of arabic numerals, kanji, and kana in brain-damaged patients.

This study investigated the neural mechanisms involved in the writing of Arabic numerals, kanji, and kana. Tasks involving writing numerals in Arabic, kanji, and, kana were administered to four patients with Gerstmann's syndrome and to five Wernicke aphasics. The results indicated that the ability to write Arabic numerals was well preserved in the Wernicke aphasics despite their serious phonological disturbances. The patients with Gerstmann's syndrome, who have a deficit with the concept of number, could write kanji numerals better than Arabic and kana numerals. Unlike Arabic numerals (ideogram) and kana (syllabogram), kanji (morphogram) have both semantic and phonetic values. The results suggested that Arabic numerals may be somesthetic and linked directly to the concept of number bypassing phonological analysis.

[Age-related working memory decline in patients with Parkinson's disease].

The purpose of this study was to investigate the age-related working memory(WM) decline in patients with Parkinson's disease(PD) using Baddeley's WM model. This model consists of the central executive (CE) and two slave systems, the phonological loop (PL) for the storage of verbal materials, and the visuospatial sketchpad(VSSP) for the storage of visuospatial information. The participants of this study were 22 PD, 11 old (age of 68-78, mean age, 70.5) and age of onset, duration of illness, medication time, and Yahr stage, global cognitive status-matched 11 young(age of 39-58, mean age, 51.5) PD, age- and educational years, global cognitive status-matched 22 normal control (NC), 11 old(age of 65-78, mean age, 70.4) and 11 young(age of 45-57, mean age, 52.4). Mental calculation span of digit sequences, digit forward and backward span, visual memory span were carried out. Age related decline of WM was found in both groups, but processing related differences were revealed between the two groups. NC group showed significant decline with aging in digit backward span. In contrast, in mental calculation span, PD groups showed significant deficit revealed in young PD group and declined significantly with aging and significant decline was not found in digit backward span. In term of the processing and difficulty of WM tasks, digit backward span that needs maintenance of digit sequences and re-ordering, was more difficult than mental calculation that needs maintenance of digit sequences, summation of the digit and updating of the results. There were not significant differences between four groups in digit forward span, visual memory span. The results indicated that the WM span in normal aging declined as task difficulty increased. Their performance decline may be caused by the CE dysfunction. On the other hand, PD showed a characteristic CE deficit observed in mental calculation even in young age and decline with aging. Such decline may be caused by peculiar processing related dysfunction of CE that assumes to be essential deficit of PD.

Deficits of working memory during mental calculation in patients with Parkinson's disease.

Using the dual task paradigm, previous studies have suggested that working memory (WM) deficit is due to depleted attention resources in patients with Parkinson's disease (PD). The aim of this study is to establish whether the WM problems in PD are due to reduced attentional set-shifting resources rather than depletion of attention resources. The task design attempts to eliminate confounding of the deficits in dealing with novel material, a problem documented in PD, by concentrating on WM tasks of mental calculation that are familiar to subjects in daily living. We also administered attention tasks, the Trail Making Test (TMT) that relies primarily on attentional set-shifting and the Kana (Japanese syllabogram) Pick-out Test instead primarily depending on depleted attention resources for allocation. A total of 24 patients with PD and 24 normal controls participated in this study. The PD group showed deficits in mental calculation span and in attentional set-shifting in the TMT-b.Considering the common deficits in alternating processing of mental calculation and TMT-b in PD, the results suggested that the central executive dysfunction in PD during mental calculations was due to reduced attentional set-shifting resources for rapidly alternating operations, rather than the depletion of attentional resources.

Magnetic molecular conductors based on BETS molecules and divalent magnetic anions [BETS = bis(ethylenedithio)tetraselenafulvalene].

Several conducting salts based on BETS [where BETS = bis(ethylenedithio)tetraselenafulvalene] molecules and divalent magnetic anions such as the (CoCl(4))(2-), (CoBr(4))(2-), and (MnBr(4))(2-) were prepared. Electrocrystallization by using the (CoCl(4))(2-) anion gave two kinds of crystals. Block-shaped crystals were cleared to be (BETS)(2)CoCl(4), which is an insulator with the high-spin state of cobalt 3d spin. On the other hand, the X-ray crystal structure analysis of a plate-shaped crystal of the (CoCl(4))(2-) salt revealed the system to be kappa-(BETS)(4)CoCl(4)(EtOH), which is metallic down to 0.7 K. The electronic band structure calculation gave a typical two-dimensional cylindrical Fermi surface. However, there is only very weak antiferromagnetic interaction between the S = 3/2 cobalt 3d spins because of its anion-solvent-intermingled layer structure. On the other hand, the electrocrystallization by using the (MnBr(4))(2-) anion yielded the plate-shaped black crystals of the (MnBr(4))(2-) salt. Crystal structure analysis of the (MnBr(4))(2-) salt showed that the salt is theta;-(BETS)(4)MnBr(4)(EtOH)(2) with alternating donor and anion-solvent mixed layers. The stacking direction in one donor layer is perpendicular to those of the neighboring layers. The electrical and magnetic properties of the theta;-(BETS)(4)MnBr(4)(EtOH)(2) salt showed the metallic behavior down to approximately 30 K and the paramagnetism of the high-spin manganese 3d spins. Band structure calculation of this salt gave an elliptical cylindrical Fermi surface. Because the Fermi surfaces of the adjacent donor layers are rotated to each other by 90 degrees, the theta-(BETS)(4)MnBr(4)(EtOH)(2) salt becomes a two-dimensionally isotropic metal.