MRI Magnet May Cause Vertigo
A study published in Current Biology online suggests that the strong magnet of an MRI pushes on fluid that circulates in the inner ear's balance center, an interaction that may lead to a feeling of unexpected or unsteady movement. The finding could call into question results of functional MRI studies designed to detect neural processing under various circumstances.
Researchers placed 10 volunteers with healthy labyrinths (inner tube-like structures in the ears that subserve balance) and two volunteers who lacked labyrinthine function into MRI scanners. They tracked vertigo, not only by using volunteers' reports, but also by looking for nystagmus (involuntary eye movements).
Combining their results with what is known about inner ear function, the researchers surmised that MRI-related vertigo most likely relates to an interplay between electrical currents flowing through the salty fluid in the canals of the labyrinth and the MRI magnetic field. Search doi:10.1016/j.cub.2011.08.029.
Brain Retraining Is New Tinnitus Treatment
Neuroscientists at the University of California, Berkeley, suggest several new approaches to tinnitus treatment, including retraining the brain, and new avenues for developing drugs to suppress the ringing of tinnitus. The findings were published online in Proceedings of the National Academy of Sciences. Experiments in the past few years have shown that the ringing doesn't originate in the inner ear, but rather in regions of the brain—including the auditory cortex—that receive input from the ear. Researchers suggest that the goal of treatment should be to reorganize the cortical map so that nerves get some input and stop their tinnitus activity, and that drugs that inhibit the spontaneous firing of the idle neurons in the auditory cortex also could be useful. Search doi:10.1073/pnas.1107998108.
Visual Habituation for Assessing Speech Perception
Assessment of speech perception in young children requires behavioral and metacognitive responses from the participant. A recent study examined whether a procedure that uses a child's looking time to illustrate perception of novel auditory stimuli could be used to measure individual differences in the perception of prosodic and segmental speech features in a group of children with cochlear implants. Participants were assessed on the perception of three speech features (vowel height, lexical stress, intonation) using a modified hybrid visual habituation paradigm (VHP).
All participants looked longer at the novel auditory stimuli during the experimental trial, suggesting the modified hybrid VHP is a promising method for assessing the perception of these three speech features in young children with cochlear implants.