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The present study combines functional magnetic resonance imaging (fMRI) and reaction time (RT) measurements to further elucidate the influence of syllable frequency and complexity on speech motor control processes, i.e., overt reading of pseudowords. Tying in with a recent fMRI-study of our group we focused on the concept of a mental syllabary housing syllable sized ready-made motor plans for high- (HF), but not low-frequency (LF) syllables. The RT-analysis disclosed a frequency effect weakened by a simultaneous complexity effect for HF-syllables. In contrast, the fMRI data revealed no effect of syllable frequency, but point to an impact of syllable structure: Compared with CV-items, syllables with a complex onset (CCV) yielded higher hemodynamic activation in motor "execution" areas (left sensorimotor cortex, right inferior cerebellum), which is at least partially compatible with our previous study. We discuss the role of the syllable in speech motor control.

Functional imaging studies have delineated a "minimal network for overt speech production", encompassing mesiofrontal structures (supplementary motor area, anterior cingulate gyrus), bilateral pre- and postcentral convolutions, extending rostrally into posterior parts of the inferior frontal gyrus (IFG) of the language-dominant hemisphere, left anterior insula as well as bilateral components of the basal ganglia, the cerebellum, and the thalamus. In order to further elucidate the specific contribution of these cerebral regions to speech motor planning, subjects were asked to read aloud visually presented bisyllabic pseudowords during functional magnetic resonance imaging (fMRI). The test stimuli systematically varied in onset complexity (CCV versus CV) and frequency of occurrence (high-frequency, HF versus low-frequency, LF) of the initial syllable. A cognitive subtraction approach revealed a significant main effect of syllable onset complexity (CCV versus CV) at the level of left posterior IFG, left anterior insula, and both cerebellar hemispheres. Conceivably, these areas closely cooperate in the sequencing of subsyllabic aspects of the sound structure of verbal utterances. A significant main effect of syllable frequency (LF versus HF), by contrast, did not emerge. However, calculation of the time series of hemodynamic activation within the various cerebral structures engaged in speech motor control revealed this factor to enhance functional connectivity between Broca's area and ipsilateral anterior insula.

Advanced applications of ultrasound in neurosurgery have been evaluated in two projects of the Ruhr Center of Excellence for Medical Engineering (KMR), Bochum, Germany. Engineers, neurologists, and neurosurgeons are cooperating within an interdisciplinary project structure, in order to practically approach neurosurgical problems by elaborating novel ultrasound-based technologies. On one hand, procedures have been implemented for an ultrasound-based registration of bone structures, applicable, amongst others, to the high-accuracy navigation of pedicle screws. On the other hand, concepts have been developed regarding a pre- and intraoperative application of ultrasound contrast agents for the detection of cerebral tumors and for the monitoring of surgery. In this article, both projects are discussed on the basis of the results obtained thus far and, furthermore, potentials of these concepts are presented that may complement or extend the scopes of the neurosurgical practice.