Data for behavioral results and brain regions showing a time effect during pair-association retrieval.

The current data article provides behavioral and neuroimaging data for the research article "Relatedness-dependent rapid development of brain activity in anterior temporal cortex during pair-association retrieval" (Jimura et al., 2016) [1]. Behavioral performance is provided in a table. Fig. 2 of the article is based on this table. Brain regions showing time effect are provided in a table. A statistical activation map for the time effect is shown in Fig. 3C of the article.

Lateral-Medial Dissociation in Orbitofrontal Cortex-Hypothalamus Connectivity.

The orbitofrontal cortex (OFC) is involved in cognitive functions, and is also closely related to autonomic functions. The OFC is densely connected with the hypothalamus, a heterogeneous structure controlling autonomic functions that can be divided into two major parts: the lateral and the medial. Resting-state functional connectivity has allowed us to parcellate the cerebral cortex into putative functional areas based on the changes in the spatial pattern of connectivity in the cerebral cortex when a seed point is moved from one voxel to another. In the present high spatial-resolution fMRI study, we investigate the connectivity-based organization of the OFC with reference to the hypothalamus. The OFC was parcellated using resting-state functional connectivity in an individual subject approach, and then the functional connectivity was examined between the parcellated areas in the OFC and the lateral/medial hypothalamus. We found a functional double dissociation in the OFC: the lateral OFC (the lateral orbital gyrus) was more likely connected with the lateral hypothalamus, whereas the medial OFC (the medial orbital and rectal gyri) was more likely connected with the medial hypothalamus. These results demonstrate the fundamental heterogeneity of the OFC, and suggest a potential neural basis of the OFC-hypothalamic functional interaction.

Relatedness-dependent rapid development of brain activity in anterior temporal cortex during pair-association retrieval.

Functional MRI studies have revealed that the brain activity in the anterior temporal cortex during memory retrieval increases over months after memory encoding. Behavioral evidence has demonstrated that long-term memory can sometimes be consolidated more rapidly in one or two days. In the present functional MRI study, we manipulated the relatedness between paired faces to be retrieved in a pair-association task. The brain activity in the anterior temporal cortex during retrieval of paired associates increased rapidly in one day, as shown in previous studies. We found that the speed of the brain activity development was dependent on the level of semantic relatedness of paired faces. The results suggest that the semantic relatedness enhances the speed of formation of memory representation in the anterior temporal cortex.

Collimator choice in cardiac SPECT with I-123-labeled tracers.

BACKGROUND: Septal penetration of high-energy photons may degrade the quality of single photon emission computed tomography (SPECT) of the heart with iodine 123-labeled tracers. We investigated the impact of collimator choice on cardiac SPECT with I-123. METHODS AND RESULTS: SPECT of a thoracic phantom containing I-123 solution was performed with a low-energy high-resolution (LEHR) collimator, special LEHR (SLEHR) collimator, and medium-energy (ME) collimator, and the cavity-to-myocardium contrast, wall thickness, and defect contrast were compared among the collimators. For all indices, use of the SLEHR collimator yielded the best results. Comparison between the LEHR and ME collimators revealed that the cavity-to-myocardium contrast and contrast for large defects were better with the ME collimator, whereas wall thickness and contrast for small defects were similar. Scatter correction by the triple-energy window method improved the indices examined; however, the superiority of the SLEHR collimator was still observed after correction. CONCLUSIONS: Collimator choice substantially influences the quality of cardiac SPECT with I-123-labeled agents, and an appropriate collimator needs to be selected in consideration of septal penetration and spatial resolution.

Effect of collimator choice on quantitative assessment of cardiac iodine 123 MIBG uptake.

BACKGROUND: Quantitative accuracy in iodine 123 studies may be impaired by septal penetration. We evaluated the effect of collimator choice on estimation of the heart-to-mediastinum (H/M) ratio in cardiac I-123 metaiodobenzylguanidine (MIBG) imaging. METHODS AND RESULTS: A low-energy high-resolution (LEHR) collimator, special LEHR (SLEHR) collimator, and medium-energy (ME) collimator were used. In experiments in which a phantom of simple geometry was used, the use of the LEHR collimator provided the lowest contrast accuracy, suggesting the effect of septal penetration. Thoracic phantom studies demonstrated contamination of heart and mediastinum counts by lung and liver activities, which was greatest with the LEHR collimator and least with the ME collimator. In 8 patients anterior chest views were acquired successively with the three collimators after I-123 MIBG injection. H/M ratios were significantly higher with the SLEHR collimator than with the LEHR collimator and were still higher with the ME collimator. The difference in H/M ratios between the LEHR and ME collimators showed a high positive correlation with the lung-to-mediastinum ratio. CONCLUSIONS: Collimator choice substantially influences estimation of the H/M ratios in cardiac I-123 MIBG imaging. The use of an ME collimator provides high quantitative accuracy and may enhance reliability in the evaluation of cardiac sympathetic nerve function.