Raimo P. Joensuu

Learn More
We investigated cerebral processing of audiovisual speech stimuli in humans using functional magnetic resonance imaging (fMRI). Ten healthy volunteers were scanned with a 'clustered volume acquisition' paradigm at 3 T during observation of phonetically matching (e.g., visual and acoustic /y/) and conflicting (e.g., visual /a/ and acoustic /y/) audiovisual(More)
OBJECTIVE We studied whether distal peripheral nerves could be imaged using quantitative diffusion tensor imaging (DTI) with a 3-T MRI scanner, and visualized using tractography. METHODS Altogether 6 healthy subjects were studied. The diffusion was quantified with apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps, and the direction(More)
Cathepsin D (CTSD; EC is essential for normal development and/or maintenance of neurons in the central nervous system: its deficiency causes a devastating neurological disorder with severely shortened life span in man, sheep and mouse. Neuropathologically, the CTSD deficiencies are characterized by selective neuronal degeneration, gliosis and(More)
Subjects sense clear mechanical vibrations during diffusion tensor imaging (DTI). These vibrations, likely resulting from diffusion-sensitizing gradients, have been assumed to be of the same strength and phase in all parts of the magnetic resonance imaging (MRI) scanner so that they could be ignored. However, our measurements, carried out from several parts(More)
BACKGROUND Aspartylglucosaminuria (AGU) is an autosomal recessive lysosomal disease caused by deficiency of aspartylglucosaminidase. A thalamic T2 signal intensity decrease is associated with lysosomal diseases. PURPOSE To investigate thalamic signal intensity in AGU by performing a retrospective review of brain magnetic resonance (MR) imaging studies of(More)
Lysosomal disorders are rare and are caused by genetically transmitted lysosomal enzyme deficiencies. A decreased T2 signal in the thalamus has occasionally been reported. Because the finding of bilateral abnormal signal intensity of the thalamus on T2-weighted images has not been systematically reviewed, and its value as a diagnostic tool critically(More)
Aspartyglucosaminuria (AGU) is a lysosomal storage disease with autosomal recessive inheritance that is caused by deficient activity of aspartylglucosaminidase (AGA), a lysosomal enzyme belonging to the newly described enzyme family of N-terminal hydrolases. An AGU mouse model was generated by targeted disruption of the AGA gene designed to mimic closely(More)
Tactile sensory memory is needed to infer shape or motion from the spatiotemporal pattern of sensory input during manual exploration. Here we applied triplets of pressure pulses to the fingertips of subjects who were asked to respond when successive triplets were the same (COMPARE task) or when a particular stimulus was included in a triplet (CONTROL task).(More)
PURPOSE We investigated the feasibility of diffusion weighted magnetic resonance imaging (MRI) for the early detection of ischemia in the testis. MATERIALS AND METHODS Circulation to the right testis in Wistar rats was occluded by surgical ligation of the right funicle. The left side was sham operated and served as a control. The diffusion and T2-weighted(More)
Functional magnetic resonance imaging (fMRI) reveals changes in blood oxygen level-dependent (BOLD) signal after considerable processing. This paper describes the implementation and testing of an fMRI phantom where electric current applied to a thin wire within a proton-rich medium substituted BOLD distortion of the magnetic field; the scanner detects these(More)