BACKGROUND AND PURPOSE: Early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD) have different clinical and neuroimaging characteristics, but memory decline is usually present in both types. However, there have been few functional studies focused on the hippocampus in Alzheimer's disease. We therefore investigated the functional connectivity between the hippocampus and other brain regions using resting-state fMRI and compared the findings between EOAD and LOAD. METHODS: We recruited 13 patients with EOAD and 19 patients with LOAD at the early disease stage. Twenty-one young controls and ten old controls were also recruited. Each participant completed a standardized neuropsychological battery of tests and underwent T1-weighted structural MRI. fMRI data were acquired during the resting state using 3-T MRI. The functional connectivity to the hippocampus was calculated based on automated anatomical labeling templates. RESULTS: The functional connectivity from the hippocampus to other brain regions differed between patients with EOAD and LOAD. The LOAD patients showed decreased hippocampal connectivity to cortical regions, such as to the middle temporal cortex, orbitofrontal cortex, postcentral cortex, supramarginal cortex, and rolandic operculum. In contrast, EOAD patients showed smaller functional changes of the cortical regions connected to the hippocampus, such as the middle frontal cortex. CONCLUSIONS: EOAD and LOAD patients exhibited different hippocampal connectivity. The memory decline in EOAD may be due to brain areas other than the hippocampus.
Alzheimer Disease* ; Brain ; Frontal Lobe ; Hippocampus* ; Humans ; Magnetic Resonance Imaging ; Memory ; Neuroimaging ; Prefrontal Cortex ; Temporal Lobe

OBJECTIVES: This study was undertaken to identify neural substrates for simple focused attention and more highly-focused working memory in normal people and investigate their characteristics and differences. METHOD: Fourteen normal subjects were studied with [15O]H 2O positron emission tomography during a visual processing baseline task, simple focused attention task and working memory task. Results were analyzed with the subtraction analysis to map the neural correlates of focused attention and working memory. RESULTS: Activated areas during focused attention tended to be lateralized to the left and scattered over various regions including the anterior cingulate, motor area, and primary and secondary visual cortices. While the areas activated during working memory also show the left lateralization and scattered distribution, activation prevailed more in the frontal lobe than in the visual cortex, and was particularly remarkable in the right anterior cingulate. CONCLULSION: Focused attention and working memory do not have only conceptually commonalities and differences but also have common and specific areas in their neural substrates. The anterior cingulate may commonly play an important role in both cognitive functions, whereas secondary visual cortex and prefrontal cortex seem to be predominantly implicated in each function, respectively.
Brain* ; Electrons* ; Frontal Lobe ; Memory, Short-Term* ; Positron-Emission Tomography* ; Prefrontal Cortex ; Visual Cortex

Absence seizures (AS) are generalized non-convulsive seizures characterized by a brief loss of consciousness and spike-and-wave discharges (SWD) in an electroencephalogram (EEG). A number of animal models have been developed to explain the mechanisms of AS, and thalamo-cortical networks are considered to be involved. However, the cortical foci have not been well described in mouse models of AS. This study aims to use a high density EEG in pathophysiologically different AS models to compare the spatiotemporal patterns of SWDs. We used two AS models: a pharmacologically induced model (gamma-hydroxybutyric acid, GHB model) and a transgenic model (phospholipase beta4 knock-out, PLCβ4 model). The occurrences of SWDs were confirmed by thalamic recordings. The topographical analysis of SWDs showed that the onset and propagation patterns were markedly distinguishable between the two models. In the PLCβ4 model, the foci were located within the somatosensory cortex followed by propagation to the frontal cortex, whereas in the GHB model, a majority of SWDs was initiated in the prefrontal cortex followed by propagation to the posterior cortex. In addition, in the GHB model, foci were also observed in other cortical areas. This observation indicates that different cortical networks are involved in the generation of SWDs across the two models.
Animals ; Electroencephalography ; Epilepsy, Absence ; Frontal Lobe ; Mice ; Models, Animal ; Prefrontal Cortex ; Seizures ; Somatosensory Cortex ; Unconsciousness

OBJECTIVE: Structural changes of brain areas have been reported in depressive disorder and suicidal behavior (SB), in which TPH1 also has been known as a promising candidate gene. We investigated gray matter volume (GMV) differences, TPH1 rs1800532 and rs1799913 polymorphisms previously found to be associated with depressive disorder and SB, and the relationship between the two markers. METHODS: Thirteen depressive disorder patients with suicidal attempts (SA) and twenty healthy controls were included. We examined GMV differences using a voxel-based morphometry and regions of interest analysis. Direct sequencing was used for genotyping. RESULTS: The patients showed significant GMV reduction in left cerebral region including middle frontal gyrus, inferior frontal gyrus, and anterior cingulate cortex; in right middle temporal gyrus; in left cerebellar tonsil; and in right cerebral region including precentral gyrus and postcentral gyrus (corrected p < 0.005). The right precentral and postcentral gyri GMV values of AA and CA genotypes patients were significantly decreased compared to those of CC genotype subjects (corrected p=0.040). CONCLUSION: These findings show the possibility that both GMV reductions and TPH1 rs1800532/rs1799913 A allele may be involved in the pathogenesis of depressive disorder patients with SA.
Alleles ; Brain ; Depressive Disorder* ; Frontal Lobe ; Genotype ; Gray Matter* ; Gyrus Cinguli ; Humans ; Palatine Tonsil ; Prefrontal Cortex ; Somatosensory Cortex ; Temporal Lobe

PURPOSE: To investigate the brain areas related with the deficit in visuospatial attention in patients with traumatic brain injury (TBI) using functional MRI (fMRI). METHOD: Twenty TBI and fifteen normal subjects were enrolled. The endogenous visuospatial attention task was used as an activation paradigm during fMRI. FMRI was performed on a 3T ISOL Forte scanner. Thirty slices were acquired using a single-shot EPI sequences (TR/TE=3000/ 30 ms, Flip angle 70 degrees, FOV=220 mm, 64x64 matrix, slice thickness 4 mm). The accuracy and reaction time to the attention task were measured during fMRI. Imaging data were analyzed using SPM-99 software. RESULTS: The ratio of accurate responses was lower (p<0.01) and the average reaction time was slower (p<0.01) in the TBI group than the normal group. The fMRI analysis showed more activation in the bilateral prefrontal cortices (the middle and inferior frontal gyri) and less activation in the cingulate gyrus, medial frontal lobe, bilateral temporo- occipital areas, and cerebellum in the TBI group compared with the normal group. CONCLUSION: In TBI patients, impaired visuospatial attention might be resulted from the decreased activity of the cingulate, medial frontal, and temporo-occipital regions accompanied with compensatory hyperactivation of the prefrontal cortex.
Brain ; Brain Injuries* ; Cerebellum ; Frontal Lobe ; Gyrus Cinguli ; Humans ; Magnetic Resonance Imaging ; Prefrontal Cortex ; Reaction Time

OBJECTIVETo explore the working mechanism and age-related change of the conflict processing system of the frontal cortex.

METHODSFifteen normal elderly people and 15 youth were performed a modified Eriksen flanker paradigm, while event-related potential (ERPs), which include 32 systerm electroencephalography, reaction time and correct rate were recorded.

RESULTSThe elderly group showed a distinct effect of reaction time and effect of conflict in the respond level compared with the youth group. The elderly group had a longer time window of N380 and same amplitude as the youth group. Low resolution brain electromagnetic tomography (LORETA) showed the bilateral temporal lobe and the dorsolateral prefrontal cortex (especially right) were activated in the youth group, while the left temporal lobe, the left dorsolateral prefrontal cortex and left medial frontal gyrus were activated in the elderly group.

CONCLUSIONWhen conflict stimuli existed in the response level, old people showed frontal interference control hypofunction. N380 reflected the activation of the left dorsolateral prefrontal cortex and the left temporal lobe during response selection and executive control processing in older people.

Adolescent ; Aged ; Aging ; Electroencephalography ; Evoked Potentials ; Frontal Lobe ; physiology ; Humans ; Prefrontal Cortex ; physiology ; Reaction Time ; Temporal Lobe ; physiology

OBJECTIVE: To investigate the effects of specific brain lesions on prognosis and recovery of post-stroke aphasia, and to assess the characteristic pattern of recovery. METHODS: Total of 15 subjects with first-ever, left hemisphere stroke, who were right handed, and who completed language assessment using the Korean version of the Western Aphasia Battery (K-WAB) at least twice during the subacute and chronic stages of stroke, were included. The brain lesions of the participants were evaluated using MRI-cron, SPM8, and Talairach Daemon software. RESULTS: Subtraction of the lesion overlap map of the participants who showed more than 30% improvement in the aphasia quotient (AQ) by the time of their chronic stage (n=9) from the lesion overlap map of those who did not show more than 30% improvement in the AQ (n=6) revealed a strong relationship with Broca's area, inferior prefrontal gyrus, premotor cortex, and a less strong relationship with Wernicke's area and superior and middle temporal gyri. The culprit lesion related to poor prognosis, after grouping the subjects according to their AQ score in the chronic stage (a cut score of 50), revealed a strong relationship with Broca's area, superior temporal gyrus, and a less strong relationship with Wernicke's area, prefrontal cortex, and inferior frontal gyrus. CONCLUSION: Brain lesions in the Broca's area, inferior prefrontal gyrus, and premotor cortex may be related to slow recovery of aphasia in patients with left hemisphere stroke. Furthermore, involvement of Broca's area and superior temporal gyrus may be associated with poor prognosis of post-stroke aphasia.
Aphasia* ; Brain ; Broca Area ; Hand ; Humans ; Motor Cortex ; Prefrontal Cortex ; Prognosis* ; Stroke* ; Temporal Lobe ; Wernicke Area

PURPOSE: To evaluate the clinical usefulness of functional MR imaging (fMRI) for localization of the cerebral motor and sensory cortices and the language center in patients with complex partial seizure. MATERIALS AND METHODS: A total of 47 fMRIs were obtained in 14 patients (M:F=9:5; age 15 -50 years; 13 right handed and 1 ambidextrous) with complex partial seizure (6 temporal lobe epilepsy, 6 frontal lobe epilepsy, 1 occipitotemporal lobe epilepsy, 1 hemispheric epilepsy). Conventional MR imaging revealed no abnormality in four patients, localized cerebral atrophy in one, hippocampal sclerosis in four, and benign neoplasm in the remaining five. fMRI was performed on a 1.5 T MR scanner (GE Signa Horizon) using gradient-echo single-shot EPI. Nineteen fMRIs were obtained in eight patients who performed the language task, 16 fMRIs in ten who performed the motor task and 12 fMRIs in ten who performed the somatosensory task. The activation task consisted of three language tasks (silent picture naming, word generation from a character, categorical word generation), motor tasks (opposition of thumb and index finger for hand/dorsiflexion or extension for foot), and sensory tasks (passive tactile stimulation of hand or foot using a toothbrush). The data were analyzed using z-score (p<0.05), clustering, and cross-correlation analysis based upon homemade software, IDL 5.1. The success rate for obtaining meaningful fMRI was evaluated and activated regions were assessed on the basis of each fMRI obtained during language, motor, and omatosensory tasks. fMRI findings were compared with those of the Wada test (n = 7) for language lateralization and with invasive cortical mapping (n = 3) for the localization of eloquent cerebral cortex, especially around the central sulcus. RESULTS: The overall success rate of fMRI was 79 % (37/47); success rates of fMRI with language, sensory, and motor tasks were 89 % (17/19), 83 % (10/12), and 63% (10/16), respectively. Areas activated during language tasks (n=17) included the dorsolateral prefrontal cortex (16/17), anterior cingulate gyrus (16/17), posterior parietal area (15/17), Wernicke's area (10/17), and Broca's area (8/17). Regions activated by motor and somatosensory tasks (n=20) included the central sulcus (16/20), prefrontal cortex (15/20), posterior parietal cortex (9/20), supplementary motor area (6/20), and temporal cortex (3/20). The results of fMRI were concordant with the Wada test in six of seven subjects (86%) for language lateralization of left hemispheric dominance and with invasive cortical mapping in two of three patients (67%) for localization of the motor and sensory cortices. CONCLUSION: fMRI was successful in approximately three-quarters of patients with complex partial seizure, but at present appears to be an inadequate alternative to current invasive studies. Further clinical investigation is needed.
Atrophy ; Cerebral Cortex ; Epilepsy ; Epilepsy, Frontal Lobe ; Epilepsy, Temporal Lobe ; Fingers ; Foot ; Gyrus Cinguli ; Hand ; Humans ; Magnetic Resonance Imaging* ; Prefrontal Cortex ; Rabeprazole ; Sclerosis ; Seizures* ; Thumb

Bruxism is a diurnal or nocturnal parafunctional activity that includes tooth clenching, bracing, gnashing, and grinding. The dopaminergic system seems to be the key pathophysiology of bruxism and diminution of dopaminergic transmission at the prefrontal cortex seems to induce it. We report two patients with diurnal bruxism in whom a bilateral frontal lobe injury resulted from hemorrhagic stroke or traumatic brain injury. These patients' bruxism was refractory to bromocriptine but responded to low-dose metoclopramide therapy. We propose that administering low doses of metoclopramide is possibly a sound method for treating bruxism in a brain injury patient with frontal lobe hypoperfusion on positron emission tomography imaging.
Braces ; Brain Injuries* ; Brain* ; Bromocriptine ; Bruxism* ; Frontal Lobe ; Humans ; Metoclopramide* ; Positron-Emission Tomography ; Prefrontal Cortex ; Receptors, Dopamine ; Stroke ; Tooth

We report a patient with a severe limitation of function in the right hand resulting from grasp reflex following a stroke affecting the left anterior cerebral artery region. We describe, using diffusion tensor tractography (DTT), a disconnection between the bilateral frontal lobes via the corpus callosum. The patient could not control his right hand at all, even though his bilateral corticospinal tracts were intact. We noted that over the infarcted lesion on DTT, the white matter was invisible from the corpus callosum to the prefrontal cortex. These findings reflected a unique pattern of white-matter disconnection between the ipsilateral medial frontal lobe and ipsilateral and contralateral frontal cortex causing hand function deterioration in the form of severe grasp reflex.
Anterior Cerebral Artery ; Corpus Callosum ; Diffusion ; Frontal Lobe* ; Hand ; Hand Strength* ; Humans ; Infarction* ; Prefrontal Cortex ; Pyramidal Tracts ; Reflex* ; Stroke