The purpose of this study was to determine, by using functional magnetic resonance imaging, the areas of the brain activated during a memory-timed finger movement task and compare these with those activated during a visually cued movement task. Because it is likely that subjects engage in subvocalization associated with chronometric counting to achieve accurate timing during memory-timed movements, the authors sought to determine the areas of the brain activated during a silent articulation task in which the subjects were instructed to reproduce the same timing as for the memory-timed movement task without any lip movements or vocalization. The memory-timed finger movement task induced activation of the anterior lobe of the cerebellum (lobules IV and V) bilaterally, the contralateral primary motor area, the supplementary motor area (SMA), the premotor area (PMA), the prefrontal cortex, and the posterior parietal cortex bilaterally, compared with the resting condition. The same areas in the SMA and left prefrontal cortex were activated during the silent articulation task compared with the resting condition. The anterior lobe of the cerebellum on both sides was also activated during the silent articulation task compared with the resting condition, but these activations did not reach statistical significance (P < 0.05 corrected). In addition, the anterior cerebellum on both sides showed significant activation during the memory-timed movement task when compared with the visually cued finger movement task. The visually cued finger movement task specifically activated the ipsilateral PMA and the intraparietal cortex bilaterally. The results indicate that the anterior lobe of the cerebellum of both sides, the SMA, and the left prefrontal cortex were probably involved in the generation of accurate timing, functioning as a clock within the CNS, and that the dorsal visual pathway may be involved in the generation of visually cued movements.

The aim of this study was to identify the neuroanatomical basis of the retrieval of people's names. Lesion data showed that patients with language-dominant temporal lobectomy had impairments in their ability to retrieve familiar and newly learned people's names, whereas patients with language-nondominant temporal lobectomy had difficulty retrieving newly learned people's names. Functional magnetic resonance imaging experiments revealed activations in the left temporal polar region during the retrieval of familiar and newly learned people's names, and in the right superior temporal and bilateral prefrontal cortices during the retrieval of newly learned information from face cues. These data provide new evidence that the left anterior temporal region is crucial for the retrieval of people's names irrespective of their familiarity and that the right superior temporal and bilateral prefrontal areas are crucial for the process of associating newly learned people's faces and names.

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Purpose: Accurate longitudinal relaxation time (T 1 ) of arterial blood is important in evaluating blood ‰ow in tissue by arterial spin labeling magnetic resonance (MR) imaging. Few studies have reported the T 1 of human arterial blood in vivo, especially using 3-tesla MR imaging. T 1 values of human venous blood in vivo have been reported, but they diŠer from those measured in vitro. We aimed to evaluate the accurate T 1 of human arterial blood in vivo.Methods: We measured T 1 values of blood in 10 healthy volunteers in vivo using an inversion-recovery fast gradient-echo sequence and 3-tesla MR imaging unit. We also measured hematocrit (Hct) values of venous blood samples. After nonselective application of the inversion pulse using a body coil, we obtained MR imaging signals of arterial blood in the abdominal aorta. Similarly, we measured the signals of venous blood in the internal jugular vein. Inversion times varied between 200 and 5000 ms for imaging of the abdominal aorta and 200 and 2500 ms for imaging of the jugular vein. We also acquired signals without the inversion pulse. We estimated T 1 values from the data by nonlinear least squaresˆtting of a 3-parameter model.Results: The T 1 value (mean±standard deviation) of arterial blood was 1779±80 ms and of venous blood, 1694±77 ms. The average Hct value was 0.47. The R 1 (＝1/T 1 ) of arterial blood was related to the Hct value as: R 1 ＝(0.59±0.16)Hct＋(0.29±0.07) (mean± standard error) s -1 . For the venous blood, R 1 ＝(0.70±0.11)Hct＋(0.27±0.05) s -1 .Conclusion: We observed a T 1 of human arterial blood in vivo of 1779±80 ms at a mean hematocrit value of 0.47 as determined by 3T MR imaging; an even longer T 1 value is expected with a hematocrit value less than 0.47.