Biomedical subjects

Emi Takahashi

Publications and source records attributed to Emi Takahashi.

4 recordsLinked to original sources

PubMed2006

Diffusion tensor studies dissociated two fronto-temporal pathways in the human memory system.

Recent functional neuroimaging studies have shown that multiple cortical areas are involved in memory encoding and retrieval. However, the underlying anatomical connections among these memory-related areas in humans remain elusive due to methodological limitations. Diffusion tensor imaging (DTI) is a technique based on detecting the diffusion of water molecules from magnetic resonance images. DTI allows non-invasive mapping of anatomical connections and gives a comprehensive picture of connectivity throughout the entire brain. By combining functional magnetic resonance imaging (fMRI) and DTI, we show that memory-related areas in the left dorsolateral prefrontal cortex (DLPFC) and the left ventrolateral prefrontal cortex (VLPFC) each connect with memory-related areas in the left temporal cortex. This result suggests there are two pathways between prefrontal cortex and temporal cortex related to the human memory system.

Adult↗

PubMed2006

Identification of the lumbar intervertebral level using ultrasound imaging in a post-laminectomy patient.

A spinal block was performed in a post-laminectomy patient, using both ultrasound imaging and X-ray imaging. Ultrasound imaging clearly identified the L3/4 intervertebral level, the spinal canal, the corpus vertebrae, and the dura mater. Using ultrasound imaging, we measured the distance from the skin surface to the dura mater (39 mm). A 25-G needle for the spinal block was accurately advanced into the spinal canal with the use of X-ray imaging (43 mm from the skin to the subarachnoid space). We report here that ultrasound imaging was useful for performing a spinal block in a post-laminectomy patient in whom there was anatomical change around the spine.

Aged, 80 and over↗

PubMed2002

The role of the parahippocampal gyrus in source memory for external and internal events.

We can discriminate between the memories of real and imagined events. In this study, the traces of the perceived external events and the imagined internal events were investigated in the established paradigm of reality monitoring using event-related fMRI. In the retrieval phase, we found that the left parahippocampal gyrus represented the traces of visually encoded memory. The right inferior parietal cortex was activated when subjects judged that the original event was imagined. We suggest that these traces are used to distinguish what is seen from what is thought during reality monitoring. Furthermore, we found that the incorrect judgments were associated with signal increases in the left frontal operculum, suggesting that this area is a candidate for the monitoring system of contextual information or failure in the retrieval phase.

Adult↗

PubMed2002

Hemispheric asymmetry in human lateral prefrontal cortex during cognitive set shifting.

Functional organization of human cerebral hemispheres is asymmetrically specialized, most typically along a verbal/nonverbal axis. In this event-related functional MRI study, we report another example of the asymmetrical specialization. Set-shifting paradigms derived from the Wisconsin card sorting test were used, where subjects update one behavior to another on the basis of environmental feedback. The cognitive requirements constituting the paradigms were decomposed into two components according to temporal stages of task events. Double dissociation of the component brain activity was found in the three bilateral pairs of regions in the lateral frontal cortex, the right regions being activated during exposure to negative feedback and the corresponding left regions being activated during updating of behavior, to suggest that both hemispheres contribute to cognitive set shifting but in different ways. The asymmetrical hemispheric specialization within the same paradigms further implies an interhemispheric interaction of these task components that achieve a common goal.

Adult↗