Eye Position Influences Auditory Responses in Primate Inferior Colliculus

AbstractWe examined the frame of reference of auditory responses in the inferior colliculus in monkeys fixating visual stimuli at different locations. Eye position modulated the level of auditory responses in 33% of the neurons we encountered, but it did not appear to shift their spatial tuning. The effect of eye position on auditory responses was substantial—comparable in magnitude to that of sound location. The eye position signal appeared to interact with the auditory responses in at least a partly multiplicative fashion. We conclude that the representation of sound location in primate IC is distributed and that the frame of reference is intermediate between head- and eye-centered coordinates. The information contained in these neurons appears to be sufficient for later neural stages to calculate the positions of sounds with respect to the eyes

Eye Position Affects Activity in Primary Auditory Cortex of Primates

AbstractBackground: Neurons in primary auditory cortex are known to be sensitive to the locations of sounds in space, but the reference frame for this spatial sensitivity has not been investigated. Conventional wisdom holds that the auditory and visual pathways employ different reference frames, with the auditory pathway using a head-centered reference frame and the visual pathway using an eye-centered reference frame. Reconciling these discrepant reference frames is therefore a critical component of multisensory integration.Results: We tested the reference frame of neurons in the auditory cortex of primates trained to fixate visual stimuli at different orbital positions. We found that eye position altered the activity of about one third of the neurons in this region (35 of 113, or 31%). Eye position affected not only the responses to sounds (26 of 113, or 23%), but also the spontaneous activity (14 of 113, or 12%). Such effects were also evident when monkeys moved their eyes freely in the dark. Eye position and sound location interacted to produce a representation for auditory space that was neither head- nor eye-centered in reference frame.Conclusions: Taken together with emerging results in both visual and other auditory areas, these findings suggest that neurons whose responses reflect complex interactions between stimulus position and eye position set the stage for the eventual convergence of auditory and visual information

Neonatal Screening for Cystic Fibrosis: Position Paper

Neonatal screening represents the search for a disorder in a general newborn population. The purpose of screening may be to improve the health of the affected infant, to provide counseling, or for research. Screening tests have been widely accepted for conditions such as phenylketonuria, hypothyroidism, and other metabolic conditions. Cystic fibrosis (CF) is the most common lethal genetic disorder among the white population (with a lower incidence among blacks), and thus there has been interest in screening newborns for CF1 However, proposals emanating from this interest have remained controversial.2-4 The recent development of a relatively simple test—the dried blood immuno-reactive trypsinogen (IRT) assay—has increased this interest.5-12 Besides considering technical reliability and validity of newborn screening methods, it is crucial that all other aspects of screening (including medical, ethical, psychosocial, and economic aspects) be rigorously examined before implementing mass screening.13-15 To address these issues the Cystic Fibrosis Foundation convened a Task Force on Neonatal Screening. Although the Task Force considered the current status of the IRT test, it focused on the generally accepted criteria for newborn screening, summarized in the Table,14 and the relationship of these criteria to the present state of knowledge related to CF. The issues identified by the Task Force, are summarized in this paper, and recommendations are presented at the conclusion. EFFECTIVENESS OF PRESYMPTOMATIC TREATMENT Evidence suggesting that the initiation of treatment before clinical manifestations of CF first appear improves prognosis has been controversial. Whereas some studies have yielded supportive data,16 others have not.4 There are no generally accepted treatment protocols for use in symptomatic or asymptomatic patients.</jats:p