Multiple combination-sensitive neurons in the auditory cortex of the mustached bat.
The mustached bat, Pteronotus parnellii, emits biosonar pulses consisting of four constant-frequency (CF(1-4)) and four frequency-modulated (FM(1-4)) components. The FM-FM area of its auditory cortex consists of three subdivisions, containing either FM(1)-FM(2), FM(1)-FM(3) or FM(1)-FM(4) combination-sensitive neurons. The FM-FM area also contains 'multiple combination-sensitive' neurons: FM(1)-FM(2,3), FM(1)-FM(3,4), FM(1)-FM(2,4), and FM(1)-FM(2,3,4) neurons. All FM-FM neurons are tuned to a time delay (echo delay) of FM(n) (n=2-4) from FM(1). In the present study, we made the following four major findings. (1) Multiple combination-sensitive neurons show the strongest response to a combination of more than two signal elements. (2) Multiple combination-sensitive neurons are located in about 100 microm wide bands at the boundaries between two adjacent subdivisions of the FM-FM area. (3) Iso-best-delay contour lines across the three single combination-sensitive subdivisions are not interrupted by multiple combination-sensitive bands. (4) Each subdivision of the FM-FM area has frequency-vs.-frequency coordinates in terms of best FM(1) and best FM(n) frequencies for facilitation, although such coordinates were not obtained with single tone bursts.
Misawa
H
H
Department of Biology, Washington University, Box 1137, One Brookings Drive, St. Louis, MO 63130-4899, USA. hayatom@tsuru.med.nagoya-u.ac.jp
Suga
N
N
D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology* / Q000502:physiology*; D002685:Chiroptera / Q000033:anatomy & histology* / Q000502:physiology*; D004455:Echolocation / Q000502:physiology; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009474:Neurons / Q000502:physiology; D014465:Ultrasonics