The MD patients did not show a significant association between their ACS oVEMP findings and ACS cVEMP findings but there was an association of ACS oVEMP findings with caloric test findings. When the MD patients were classified into four stages based on their hearing levels, the patients showed abnormal findings at earlier stages on ACS cVEMP than on other tests. While all six VN patients showed abnormal findings on ACS oVEMP and caloric tests, only two patients showed abnormal ACS cVEMPs. These findings support the hypothesis that the oVEMP in response to ACS predominantly reflects utricular functions while ACS cVEMP reflects saccular functions.

Environmental acoustic exposure to a complex tone sequence within the critical period in infant rats resulted in the emergence of large-scale, selective changes that radically altered primary auditory cortex (A1) organization. In the sound exposure-revised A1, responses were segregated into two explicit zones representing spectrally and temporally separated lower and higher frequency tone sequence progressions. Cortical neurons between these two A1 zones were poorly driven by sound stimuli. Stimulus sequence-specific (''combination-selective'') responses emerged in the A1 of exposed rats. These selective representational changes induced in the critical period persisted into adulthood. These results show that the temporal order and pace of early, repetitive postnatal auditory inputs strongly affect the emergent and enduring functional organization of A1.A uditory experience plays an important role in the development of the primary auditory cortex (A1) (1-10). Exposure of kittens or rat pups to a modulated tonal stimuli during an early postnatal period resulted in an expansion of the representation of the exposed sound frequency in A1 (2, 7). Synchronous electrical stimulation of a cochlear implant in congenitally deaf cats led to larger cortical regions producing middle-latency evoked responses (11). The formation of an orderly, continuous sound frequency (''tonotopic'') representation and a postnatal sharpening of tonal receptive fields in the rat A1 appeared to require exposure to normally variable auditory inputs during the ''critical period'' (ref. 1, but also see ref. 12 for a difference in cats). However, it remains unclear how the cortical representations of the dynamic aspects of complex sound are specifically shaped by the spectro-temporal patterns of auditory inputs during development. These studies were designed to initiate our attack on this important issue.In this initial study, we exposed rat pups through a critical period epoch extending from postnatal day (P) 9 (before hearing is first functional, at ϷP12) to P30 (when the critical period is drawing to a close) to a tone sequence with two specific spectro-temporal patterns. The frequency representation of A1 was radically revised by the exposure to this complex acoustic stimulus. Cortical neurons developed a preference for the temporal sequences of sound that the infant rat was exposed to. Induced changes endured into adulthood. These results underscore the specific instructive role of early auditory experience in sculpting the specific circuits of the auditory system to selectively and enduringly represent inputs that are present in the criticalperiod acoustic environment. MethodsEarly Exposure of Rat Pups. All of the experimental procedures applied in this study were approved by the University of California San Francisco animal research committee. Litters of nine to twelve 9-day-old female rats (Sprague-Dawley) were placed with their mothers in a calibrated, sound-shielded test chamber from P9 to P30 in the presence of auditory stimulation consi...

More of the patients with pBPPV showed abnormal responses in oVEMPs by stimulation on their affected side than the controls, while the results of cVEMPs showed no significant differences between pBPPV patients and controls. The abnormal results for oVEMPs on the affected side showed a higher percentage than those for cVEMPs and caloric tests in pBPPV patients. There was no significant association between any of the tests. These findings support the possibility that oVEMP reflects the specific abnormal condition in pBPPV, i.e. that the urticular function in pBPPV patients was highly damaged.

VIN testing is a simple and sensitive clinical test that indicates unilateral vestibular dysfunction.