Processing of interaural intensity differences in the LSO: role of interaural threshold differences.
نویسندگان
چکیده
Cells in the lateral superior olive (LSO) are known to be sensitive to interaural intensity differences (IIDs) in that they are excited by IIDs that favor the ipsilateral ear and inhibited by IIDs that favor the contralateral ear. For each LSO neuron there is a particular IID that causes a complete inhibition of discharges, and the IID of complete inhibition varies from neuron to neuron. This variability in IID sensitivity among LSO neurons is a key factor that allows for the coding of a variety of IIDs among the population of cells. A fundamental question concerning the coding of IIDs is: how does each cell in the LSO derive its particular IID sensitivity? Although there have been a large number of neurophysiological studies on the LSO, this question has received little attention. Indeed, the only reports that have directly addressed this question are those of Reed and Blum, who modeled the binaural properties of LSO neurons and proposed that the IID at which discharges are completely suppressed should correspond to the difference in threshold between the excitatory, ipsilateral and inhibitory, contralateral inputs that innervate each LSO cell. The main purpose of this study was to test the threshold difference hypothesis proposed by Reed and Blum by recording responses to monaural stimulation and to IIDs from single cells in the LSO of the mustache bat. Our results show that although the IID sensitivities of some LSO cells correspond to the difference in threshold between the excitatory and inhibitory ears, in the majority of cells the difference in thresholds did not correspond to the cell's IID sensitivity. The results lead us to propose two models to account for IID sensitivities. One model is similar to that proposed by Reed and Blum and emphasizes differences in the thresholds of the excitatory and inhibitory inputs. This model accounts for the minority of cells in which the IID of complete inhibition corresponded to the difference in threshold of the inputs from the two ears. The other model, which accounts for the cells in which the IID of complete inhibition did not correspond to the difference in the thresholds of the inputs from the two ears (the majority of cells), places emphasis on differences in latencies of the excitatory and inhibitory inputs. The models incorporate features that are concordant with the known properties of the neurons that project to the LSO and together can account for the diversity of IID sensitivities among the population of LSO neurons.
منابع مشابه
Neural delays shape selectivity to interaural intensity differences in the lateral superior olive.
Neurons in the lateral superior olive (LSO) respond selectively to interaural intensity differences (IIDs), one of the chief cues used to localize sounds in space. LSO cells are innervated in a characteristic pattern: they receive an excitatory input from the ipsilateral ear and an inhibitory input from the contralateral ear. Consistent with this pattern, LSO cells generally are excited by soun...
متن کاملTuning Neurons to Interaural Intensity Differences Using Spike Timing-Dependent Plasticity
Mammals are known to use Interaural Intensity Difference (IID) to determine azimuthal position of high frequency sounds. In the Lateral Superior Olive (LSO) neurons have firing behaviours which vary systematicaly with IID. Those neurons receive excitatory inputs from the ipsilateral ear and inhibitory inputs from the contralateral one. The IID sensitivity of a LSO neuron is thought to be due to...
متن کاملAuditory Lateralization Ability in Children with (Central) Auditory Processing Disorder
Objectives: The aim of the present study was to assess the auditory lateralization ability in children with (central) auditory processing disorder. Methods: Participants were divided in two groups: 15 children with Central Auditory Processing Disorder (8-10 years) and 80 normal children (8-11 years) from both genders with pure-tone air-conduction thresholds better than 20 dB HL bilaterally a...
متن کاملMechanisms underlying the sensitivity of neurons in the lateral superior olive to interaural intensity differences.
The initial processing of interaural intensity differences (IIDs), the major cue to the azimuthal location of high-frequency sounds in mammals, is carried out by neurons in the lateral superior olivary nucleus (LSO) that receive excitatory input from the ipsilateral ear and inhibitory input from the contralateral ear (IE neurons). The "latency" hypothesis asserts that it is the effects of inten...
متن کاملInteraural level difference discrimination thresholds for single neurons in the lateral superior olive.
The lateral superior olive (LSO) is one of the earliest sites in the auditory pathway that is involved in processing acoustical cues to sound location. Here, we tested the hypothesis that LSO neurons can signal small changes in interaural level differences (ILDs), a cue to horizontal sound location, of pure tones based on discharge rate consistent with psychophysical performance in the discrimi...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of neurophysiology
دوره 77 6 شماره
صفحات -
تاریخ انتشار 1997