The role of the thalamus in recovery from tactile extinction and crossed tactile extinction.

A 68-year-old man had a cerebral infarction affecting the right parietal lobe, right insula, and the left prefrontal region. On admission, left hand tactile extinction was noted when the hands were placed both in anatomical and crossed positions, but was noted only in crossed positions from day 20 and later. Five months later, the patient developed another cerebral infarction in the right thalamus, and left hand tactile extinction was again seen both in the anatomical and crossed positions. Our findings suggest that the thalamus was involved in the recovery from the tactile extinction in anatomical positions.

Effects of mental rotation on acalculia: differences in the direction of mental rotation account for the differing characteristics of acalculia induced by right and left hemispheric brain injury.

We observed a 59-year-old right-handed man with an infarction in his right-middle cerebral artery that included the parietal lobe, who abnormally manipulated mental images in the horizontal direction, resulting in calculation disturbances. Three years later, the patient suffered an infarction in the left parietal lobe and displayed abnormalities during the creation of mental images; i.e., he rotated them in the vertical direction, which again resulted in calculation disturbances. These mental imagery disturbances might indicate that a common acalculia mechanism exists between the right and left hemispheres.

Reversible alcohol-related dementia: a five-year follow-up study using FDG-PET and neuropsychological tests.

OBJECTIVE: As the pathophysiology of alcohol-related dementia (ARD) is unclear, we examined a patient with reversible ARD using neuropsychological tests and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). DESIGN: A five-year follow-up case study with neuropsychological tests and FDG-PET. SETTING: Kyoto University Hospital. Patients A 42-year-old patient who was unable to perform his office duties because of slowly progressive amnesia with executive dysfunction. RESULTS: The initial evaluation with neuropsychological tests showed severe verbal memory disturbance. The patient did not discuss his excessive alcohol consumption in the initial history-taking session and thiamine deficiency was absent; therefore, early-stage Alzheimer's disease was suspected. Later, the patient revealed prior excessive alcohol intake and his cognitive function improved markedly after a period of abstinence. Retrospective analysis of initial FDG-PET images using a voxel-wise statistical method revealed glucose hypometabolism in the diencephalon and basal forebrain. Follow-up for 5 years after the initial evaluation showed improved cognitive function and recovery of glucose metabolism in the two brain regions. CONCLUSION: Hypofunction in the diencephalon and basal forebrain was associated with cognitive decline in our patient. This case may provide evidence for the etiopathic brain regions in reversible type ARD.

Gliomatosis cerebri presenting as a parkinsonian syndrome.

We report a 70-year-old man who was hospitalized after a left-sided partial seizure progressed to grand mal seizures. Three years before, the patient had presented with the main symptoms of bradykinesia and gait disturbance and was diagnosed with parkinsonism resistant to L-dopa. At the latest admission, extensive diffuse white matter high-intensity areas were present on T2-weighted magnetic resonance imaging images, and stereotactic brain biopsy showed that these lesions were gliomatosis cerebri (GC). This is the first reported case in which extensive lesions in the bilateral white matter have been associated with parkinsonism as the main clinical feature; only one other case has been reported in which GC presented as parkinsonism, and this differed from the current case with respect to localization and symptoms. We speculate that damage to the thalamocortical projections and functional impairment due to demyelination could have caused parkinsonism in our patient, and we discuss the differential diagnosis.

Reverse sequencing syllables of spoken words activates primary visual cortex.

Using fMRI, we investigated the neural correlates for sequencing the individual syllables of spoken words in reverse order. The comparison of this task to a control task requiring subjects to repeat identical syllables given acoustically revealed the activation of the primary visual cortex. Because one syllable is generally expressed by one kana character (Japanese phonogram), most subjects used a strategy in which the kana character string corresponding to the word was imagined visually and then read mentally in reverse order to perform the task effectively. Such strategy was not used during a control condition. These results suggest that the primary visual cortex plays a role in the generation of an imagined string.

Parieto-frontal networks for clock drawing revealed with fMRI.

We studied the neural substrates of clock drawing using functional magnetic resonance imaging in 18 right-handed volunteers. In the test condition, subjects were required to draw the hands of a clock corresponded to the time presented acoustically. In the control task, they drew horizontal and vertical lines after reciting silently the numerals of three figures presented acoustically. In group analyses, comparison between the test and control condition revealed brain areas related to clock drawing; bilateral posterior parietal cortices with a right side dominance, bilateral dorsal premotor areas, the left pre-supplementary motor area, the left ventral prefrontal cortex, the left precentral gyrus, and bilateral cerebellum. In particular, the posterior parietal cortex and the dorsal premotor area, which were strongly activated in all 18 subjects examined in individual analyses, appear to be the main constituent of the parieto-frontal cortical networks for clock drawing.