![]() Neurons of the PB class have previously been found to have nonmonotonic selectivity for ILDs near zero. Monaural rate/level functions are monotonic for some of these neurons and nonmonotonic for others. Some monaurally responsive TWINs are contralaterally excitable and ipsilaterally unresponsive (EO), some are ipsilaterally excitable and contralaterally unresponsive (OE), and a few are bilaterally excitable (EE). Some are responsive only under binaural conditions. Under monaural conditions, TWIN neurons exhibit diverse properties. The distribution of best frequencies for TWIN neurons is broad. Thus there is commonly a nonmonotonic relation between response magnitude and ABL and sometimes a TWIN tuning to ABL and ILD. These characteristics can also be described in terms of average binaural level (ABL) and interaural level difference (ILD). Of these units, 47 displayed clear bilateral nonmonotonicity (TWIN tuning), 17 units displayed only unilateral nonmonotonicity, and an additional 17 units showed intermediate (or transitional) characteristics between unilateral and bilateral nonmonotonicity. Under binaural conditions, 62% of our sample of well documented neurons (81/130) exhibited a nonmonotonic relation between response magnitude and the SPL at one or the other ear. We have described such units as being influenced by a Two-Way Intensity Network (TWIN). ![]() Here we explore in more detail the mechanisms underlying the properties of the largest single class of binaural response, characterized by joint nonmonotonic tuning to the SPLs at the two ears. In the preceding paper, we illustrated the different forms of response observed in our sample of units. For each unit, many binaural combinations of SPL were tested by using best-frequency tone pips presented to each ear independently via sealed stimulus delivery systems. The influence of sound pressure level (SPL) at the two ears was studied in single-neuron responses recorded in high-frequency regions of primary auditory cortex (AI) of anesthetized cats.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |