The prefrontal cortex is functionally divided into three parts ; the dorsolateral, orbital and medial prefrontal cortices(MPFC). In this review, functional characteristics of MPFC were described based on observation of a particular patient with focal MPFC lesion and recent functional neuroimaging experiments of healthy persons. Functions of MPFC could be divided into two distinct components; i.e., subgoal processing and affective valence. The subgoal processing, which is mediated by the more anterior part of MPFC, is crucial for problem-solving process involving multiple and different cognitive processes. Specifically, MPFC subserves internally generated informations, thoughts and actions. This internally generated information is particularly important when therapists consider interventions to help individuals with memory impairment. The affective valence appears to be mapped in the more posterior part of MPFC. This brain area subserves self-related affective judgment and theory of mind(ToM). It is important to clarify how the affective valence and ToM is impaired in patients with MPFC. However, future studies should also shed light on how such higher order feeling is developed and acquired.

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 It has been repeatedly reported that pantomiming the use of visually presented objects and actual object use are separately impaired. This suggests that pantomiming and actual object use have different neural bases. However, how pantomiming differs from actual object use has not been completely examined. In particular, only a few examinations of the input process of action preparation have been conducted. The present study compared gaze patterns between pantomiming and actual object use with an eye mark recorder.
 Six healthy right-handed college students participated in the experiment. Ten manipulatable objects were used as the stimuli. The participants were instructed to respond either by pantomiming the use of seen objects(PANTOMIME condition)or by actually grasping the object(ACTUAL USE condition). While the participants responded, eye movement was recorded by the pupil/cornea reflection method with an eye mark recorder(EMR-8, nac). Eye mark data and the participants' movements were recorded on VTR. In the eye movement analysis, the object was divided into three parts : the graspable(e. g., handle, grip, etc.), center, and functional parts(e. g., blade of knife, head of hammer, etc.). The number of fixations was counted for each part.
 As a result, movement latency was longer in the PANTOMIME condition than in the ACTUAL USE condition. With regard to the gaze pattern, the participants fixated more on the graspable part of the objects in the ACTUAL USE condition than in the PANTOMIME condition. The participants fixated more on the functional part of the objects in the PANTOMIME condition than in the ACTUAL USE condition.
 Since pantomiming required additional time for movement onset, pantomiming might involve further processing. The differences in eye movement patterns indicated that functional information might undergo greater processing during pantomiming, while during actual object use, the shape of the graspable part would undergo processing with respect to the configuration of the hand grasping the object. The difference between pantomiming and actual object use is considered to have originated from the visual analysis of objects.

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The present study examined whether impairment of instrumental activities of daily living(IADL)predicts the progression to dementia in subjects with mild cognitive impairment(MCI). In a cohort study (Osaki-Tajiri project), in which cognitive status of habitants of 65 years or older was followed up, we reexamined in 2005 392 subjects who had MCI at the baseline 1998 survey. MCI was defined as Clinical Dementia Rating(CDR)of 0.5, and dementia as CDR 1 or more. Of 392 subjects, 165 subjects who completed the assessment with the Mini-Mental State Examination(MMSE)and Hyogo Activities of Daily Living Scale(HADLS)at the baseline and consented the 2005 survey were the subjects of the present analysis. At the 2005 survey, 58 subjects were converted to dementia. Multiple logistic regression analysis revealed MMSE and age were as significant factors(p < 0.05)for conversion to dementia, when men and women were combinedly analyzed, whereas MMSE was a sole significance factor(p < 0.05), when men and women were separately analyzed. Although some of the HADLS scores were significant factors for conversion to dementia in univariate analysis, none of the HADLS scores were predictors for it when age and MMSE were taken into consideration. This study indicated that cognitive function is most powerful predictor for conversion to dementia, and IADL is not an independent predictor for it.

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We reported a patient who showed a history and neurobehavioral and neuropsychological features resembling those of diffuse neurofibrillary tangles with calcification(DNTC), but who exhibited only slight calcification of the basal ganglia in the brain CT. A 73-year-old right-handed retired nurse presented to us with a 12-year history of abnormal behavior. At the age of 63, she repeatedly complained of anal pain, for which the psychiatric diagnosis was “psychosomatic”. At 67 years of age, she showed visual and auditory hallucinations. The complaint of anal pain subsided at the age of 70. She developed forgetfulness and delusions of persecution at the age of 71, and showed apathy, indifference to self-hygiene and timetable-like stereotyped behavior at the age of 72. A neurological examination was normal. She scored 28/30 on the MMSE and 7/70 on the Alzheimer's Disease Assessment Scale(ADAS). Amnesia and constructional disturbances were minimal, and she showed no aphasia, ideomotor or ideational apraxia, or visuocognitive disturbances. On the other hand, executive dysfunction was apparent and extensive on various tasks including the Porteus Maze, Wisconsin Card Sorting Test and Behavioural Assessment of the Dysexecutive Syndrome(BADS). In daily living, disinhibition, irritability, stereotyped behavior and timetable-like daily living were observed. A brain CT revealed frontal atrophy and spotty calcifications of minimal degree in the bilateral basal ganglia. A single photon emission CT(SPECT)showed medial frontal and anterior temporal hypoperfusions. The patient's current neurobehavioral and neuropsychological syndrome is consistent with the clinical features of frontotemporal dementia(FTD). However, her history, including extremely slow progression and hallucinations and delusions in the early disease stage, is inconsistent with frontotemporal lobar degeneration(FTLD). Taken together, the clinical features rather resemble those of DNTC. We discussed possible clinical diagnosis of the patient as DNTC associated with slight brain calcification in CT.

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In the present study we investigated the influence of aging on the ability to use Japanese particles, in order to evaluate the comprehension and generation of particles among the older elderly. To assess the various cognitive abilities of the older elderly, six participants with a mean age of 77.8 years(mean education 12. 1 years)were asked to take a Japanese version of the Mini-Mental State Examination(MMSE), Frontal Assessment Battery(FAB), Word Fluency Test(WFT), JWU Japanese Test for Comprehension of Syntax and Semantics(J.COSS), and a particle task test. Although the participants' MMSE scores reflected a nearly intact cognitive function, their FAB, WFT, and J.COSS scores showed age-related deterioration with regard to comprehension and generation of particles. Even after a month's training focused on particles, their cognitive abilities remained unchanged. However, the participants' scores on J.COSS and the particle task showed a significant increase in their grammatical abilities. Given that scores on the pre-training particle task significantly correlated with those on MMSE, there is a possibility of recovering the general cognitive function through long-term training. These results suggest that training using comprehension and generation of particle tasks may be an effective tool for maintaining cognitive ability and for improving the grammatical ability of the older elderly.

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 We reported a 67-year-old right-handed woman who developed a mirror sign following primary progressive conduction aphasia. She then also developed disturbances in visuospatial skills, ideational praxis and finger identification in addition to aphasia. Her day-to-day memory and Instrumental Activities of Daily Living were preserved or mildly degraded. 99mTc-ECD-SPECT demonstrated hypoperfusion of the bilateral parietal and frontal regions in addition to the left posterior temporo-parietal regions. The mirror sign was typically observed when she consciously looked into a mirror, as she could still use a mirror to apply make-up.
 These findings suggest that the mirror sign observed here was associated with frontal lobe dysfunction which misled the configural judgement of herself based on the temporo-parietal lobe dysfunction, resulting in impairments in language and processing of visual information.

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