Anterior medial temporal lobe activation during attempted retrieval of encoded visuospatial scenes: an event-related fMRI study.

Various studies have shown that the medial temporal lobe (MTL), which consists of the hippocampus and parahippocampal gyrus, is important for episodic memory. Earlier fMRI studies substantiated this role by showing activation upon encoding of visuospatial scenes. In this study we used event-related fMRI to study whether the cognitive process of retrieval of visuospatial scenes, tested with the use of a recognition paradigm, also activates the MTL.

Functional MR imaging in Alzheimer's disease during memory encoding.

Background And Purpose: We applied functional MR imaging with a learning task in healthy elderly volunteers and in patients with Alzheimer's disease to study brain activation during memory performance. The purpose was to determine the feasibility of functional MR imaging during a learning task in healthy elderly volunteers and in patients with Alzheimer's disease and to test our hypothesis that brain activation is decreased in the medial temporal lobe (MTL) memory system in patients with Alzheimer's disease compared with control volunteers.

Methods: In 12 patients with mild to moderate forms of Alzheimer's disease and 10 elderly control volunteers, activation of the MTL memory system was studied.

Visualizing brain activation during planning: the tower of London test adapted for functional MR imaging.

Background And Purpose: Recent positron emission tomography and single-photon emission CT studies using the Tower of London test have shown that brain activation during planning activities primarily resides in the prefrontal cortex. In this study, we adapted the Tower of London test for functional MR imaging.

Methods: For use with functional MR imaging, a block design of the test was created, in which planning stages were contrasted with counting of colored balls.

Cortico-hippocampal communication by way of parallel parahippocampal-subicular pathways.

The hippocampal memory system, consisting of the hippocampal formation and the adjacent parahippocampal region, is known to play an important role in learning and memory processes. In recent years, evidence from a variety of experimental approaches indicates that each of the constituting fields of the hippocampal memory system may serve functionally different, yet complementary roles. Understanding the anatomical organization of cortico-parahippocampal-hippocampal connectivity may lead to a further understanding of these potential functional differences.

FMRI of visual encoding: reproducibility of activation.

fMRI, a noninvasive technique to measure brain activation, is gaining clinical interest, because its sensitivity enables individual assessments. However, more insight in the reproducibility of these measurements during higher cognitive tasks is necessary. We performed an fMRI study involving within- and between-subject reproducibility during encoding of complex visual pictures.