Song pattern recognition in the vocal control nucleus (RA) of the songbird

1995 Fiscal Year Final Research Report Summary

• Project/Area Number: 06680791
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Neuroscience in general
• Research Institution: Dokkyo University
• Principal Investigator: MAEKAWA Masao Dokkyo Univ., Sch.of Med.Senior Instructor, 医学部, 講師 (50103312)
• Project Period (FY): 1994 – 1995
• Keywords: Songbird / Song learning / Auditory / Vocal control nuclei / Zebra finch / Vocal recognition / Harmonic / Parallel processing

Research Abstract

The robust nucleus of the archistriatum (RA), one of the song control nuclei in the zebra finch brain, receives its main auditory inputs from the higher vocal center (HVC) and the lateral portion of the magnocellular nucleus of the anterior neostriatum (IMAN). To clarify sound recognition mechanisms in the RA,we (1) recorded the auditory response patterns of neurons in the RA of male zebra finches and compared them with those in the IMAN,and (2) investigated integrative auditory functions in the RA.
(1) The zebra finches' distance call include a fundamental and its harmonics. One or more harmonics are usually suppressed. Our previous studies showed that neurons in the IMAN respond selectively to a specific harmonic suppression pattern (suppression-pattern selective neurons). We could also record suppression-pattern selective neurons in the RA.However, suppression-pattern selective neurons in the RA respond to the distance call in which all harmonics are present (H+) or the second harmon ic is suppressed (H2-), while in the IMAN,they respond to the distance call in which first or third harmonic is suppressed (H1- or H3-). Behavioral experiments suggest that second and third harmonics carry different behavioral information. We speculated that the RA and IMAN process different aspects of sound information in parallel.
(2) To understand the integration of auditory inputs within the RA,we investigated the effects of the bilateral electrolytic lesions in IMAN.The percentage of the suppression-pattern selective neurons which respond to H+ was identical in IMAN lesioned and normal birds. However, the suppression-pattern selective neurons which respond to H1-were much more numerous and the suppression-pattern selective neurons which respond to H2-were fewer in IMAN lesioned birds than in normal birds.
We speculate that the auditory inputs from HVC and IMAN are integrated in the RA to form suppression-pattern selective neurons.and that the RA and IMAN process different features of the auditory information in parallel.