Mechanisms and time course of vocal learning and consolidation in the adult songbird

J Neurophysiol. 2011 Oct;106(4):1806-21. doi: 10.1152/jn.00311.2011. Epub 2011 Jul 6.

Abstract

In songbirds, the basal ganglia outflow nucleus LMAN is a cortical analog that is required for several forms of song plasticity and learning. Moreover, in adults, inactivating LMAN can reverse the initial expression of learning driven via aversive reinforcement. In the present study, we investigated how LMAN contributes to both reinforcement-driven learning and a self-driven recovery process in adult Bengalese finches. We first drove changes in the fundamental frequency of targeted song syllables and compared the effects of inactivating LMAN with the effects of interfering with N-methyl-d-aspartate (NMDA) receptor-dependent transmission from LMAN to one of its principal targets, the song premotor nucleus RA. Inactivating LMAN and blocking NMDA receptors in RA caused indistinguishable reversions in the expression of learning, indicating that LMAN contributes to learning through NMDA receptor-mediated glutamatergic transmission to RA. We next assessed how LMAN's role evolves over time by maintaining learned changes to song while periodically inactivating LMAN. The expression of learning consolidated to become LMAN independent over multiple days, indicating that this form of consolidation is not completed over one night, as previously suggested, and instead may occur gradually during singing. Subsequent cessation of reinforcement was followed by a gradual self-driven recovery of original song structure, indicating that consolidation does not correspond with the lasting retention of changes to song. Finally, for self-driven recovery, as for reinforcement-driven learning, LMAN was required for the expression of initial, but not later, changes to song. Our results indicate that NMDA receptor-dependent transmission from LMAN to RA plays an essential role in the initial expression of two distinct forms of vocal learning and that this role gradually wanes over a multiday process of consolidation. The results support an emerging view that cortical-basal ganglia circuits can direct the initial expression of learning via top-down influences on primary motor circuitry.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Basal Ganglia / growth & development
  • Basal Ganglia / physiology
  • Brain Mapping
  • Cerebrum / growth & development
  • Cerebrum / physiology*
  • Excitatory Amino Acid Antagonists / administration & dosage
  • Excitatory Amino Acid Antagonists / pharmacology
  • Feedback, Sensory
  • Finches / growth & development
  • Finches / physiology*
  • GABA-A Receptor Agonists / administration & dosage
  • GABA-A Receptor Agonists / pharmacology
  • Glutamic Acid / physiology
  • Learning / drug effects
  • Learning / physiology*
  • Male
  • Motor Cortex / growth & development
  • Motor Cortex / physiology
  • Neural Pathways / physiology
  • Receptors, GABA-A / drug effects
  • Receptors, GABA-A / physiology
  • Receptors, N-Methyl-D-Aspartate / drug effects
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Reinforcement, Psychology
  • Sodium Channel Blockers / administration & dosage
  • Sodium Channel Blockers / pharmacology
  • Sodium Channels / drug effects
  • Sodium Channels / physiology
  • Time Factors
  • Vocalization, Animal / drug effects
  • Vocalization, Animal / physiology*

Substances

  • Excitatory Amino Acid Antagonists
  • GABA-A Receptor Agonists
  • Receptors, GABA-A
  • Receptors, N-Methyl-D-Aspartate
  • Sodium Channel Blockers
  • Sodium Channels
  • Glutamic Acid