An essential role of random arrangement of coincidence detection neurons in hyperaccurate sound location of owl

The sound location of owl with respect to horizontal direction is made base d on analyses of the interaural differences in arrival time of which minimu m value is of the order of mus. We proposed that this hyperacuity for detec tion of the difference is accomplished through a combination of four kinds of functional factors: (1) the functional structure of neural unit (CD unit ) for coincidence detection; (2) projection of CD units randomly arranged i n every array of the units in nucleus laminaris (NL) to ITD sensitive neuro ns arranged regularly and densely in a single array in central nucleus of t he inferior colliculus (ICc); (3) convergence of outputs of all the arrays in NL tuned to a single sound frequency in NL into a single array of the ne urons in ICc; and (4) integration of outputs of frequency tuned arrays in I Cc over all frequencies in external nucleus of inferior colliculus (ICx). ( C) 2001 Elsevier Science B.V, All rights reserved.