Pekka T Niemi

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Competing predictions concerning phoneme discrimination were tested by means of event-related potentials. In research on speech perception, one tradition stems from the physiology of the auditory system whereas another emphasizes categorical perception which involves a marked psychological component. The stimuli were the end points of the Finnish (i)-(y)(More)
Event-related potentials were recorded from four aphasic subjects in order to study if discrimination of synthetic vowels is impaired by left posterior brain damage. A component called the mismatch negativity (MMN) which is assumed to reflect basic discriminatory processes of auditory stimuli was measured. In accordance with the hypothesis, two patients(More)
Coronary flow reserve (CFR) measurements have been widely used in assessing the functional significance of coronary artery stenosis because they are more sensitive in predicting major cardiac events than angiographically detected reductions of coronary arteries. Myocardial blood flow can be determined by measuring coronary sinus (CS) flow with(More)
Meta-analytic techniques were used to assess whether successes and failures can be used experimentally to induce affective states. Data from 32 studies, with a total of 2,468 participants, were reviewed. Methods for producing success-failure experiences, as well as the resulting affective reactions, were analyzed. Effect sizes as a result of various methods(More)
Detection of early vascular changes indicated by lowered coronary flow reserve (CFR) would allow early treatment and prevention of atherosclerosis. The purpose of this study was to test whether it is possible to reproducibly measure CFR with transthoracic Doppler echocardiography (TTE) in healthy volunteers. We measured CFR using dipyridamole infusion in(More)
OBJECTIVE This study was performed to determine whether MR imaging can be used to reliably measure global myocardial blood flow and coronary flow reserve in patients with coronary artery disease as compared with such measurements obtained by positron emission tomography (PET). SUBJECTS AND METHODS We measured myocardial blood flow first at baseline and(More)
By means of the moving window paradigm, we examined how many letters can be identified during a single eye fixation and whether this letter identity span changes as a function of reading skill. The results revealed that 8-year-old Finnish readers identify approximately 5 characters, 10-year-old readers identify approximately 7 characters, and 12-year-old(More)
The facilitation of eye movements was studied in two experiments involving a repeated reading paradigm. A text was read three times. Initial reading was immediately followed by the first repetition; the second repetition took place one week later. Recall task instructions were used to encourage a detailed reading of the text. The data were analysed sentence(More)
The time-dependent saturation transfer technique was used to measure the transfer of magnetization in several rat tissues at 0.1 T. The length of the saturation pulse was varied from 0 to 510 msec. The magnetization transfer contrast effect was characteristic for each type of tissue. A substantial reduction of image intensity was obtained in skeletal muscle(More)
Myocardial perfusion reserve (MPR, defined as the ratio of the maximum myocardial blood flow (MBF) to the baseline) is an indicator of coronary artery disease and myocardial microvascular abnormalities. First-pass contrast-enhanced magnetic resonance imaging (CE-MRI) using gadolinium (Gd)-DTPA as a contrast agent (CA) has been used to assess MPR. Tracer(More)