PMID- 16107531
OWN - NLM
STAT- MEDLINE
DCOM- 20060125
LR  - 20191210
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 94
IP  - 6
DP  - 2005 Dec
TI  - Silent synapses in a thalamo-cortical circuit necessary for song learning in 
      zebra finches.
PG  - 3698-707
AB  - Developmental changes in synaptic properties may act to limit neural and 
      behavioral plasticity associated with sensitive periods. This study characterized 
      synaptic maturation in a glutamatergic thalamo-cortical pathway that is necessary 
      for vocal learning in songbirds. Lesions of the projection from medial 
      dorsolateral nucleus of the thalamus (DLM) to the cortical nucleus lateral 
      magnocellular nucleus of the anterior nidopallium (LMAN) greatly disrupt song 
      behavior in juvenile birds during early stages of vocal learning. However, such 
      lesions lose the ability to disrupt vocal behavior in normal birds at 60-70 days 
      of age, around the time that selective auditory tuning for each bird's own song 
      (BOS) emerges in LMAN neurons. This pattern has suggested that LMAN is involved 
      in processing song-related information and evaluating the degree to which vocal 
      motor output matches the tutor song to be learned. Analysis of reversed 
      excitatory postsynaptic currents at DLM-->LMAN synapses in in vitro slice 
      preparations revealed a pronounced N-methyl-D-aspartate receptor (NMDAR)-mediated 
      component in both juvenile and adult cells with no developmental decrease in the 
      relative contribution of NMDARs to synaptic transmission. However, the synaptic 
      failure rate at DLM-->LMAN synapses in juvenile males during the sensitive period 
      for song learning was significantly lower at depolarized potentials than at 
      hyperpolarized potentials. In contrast, the failure rate at DLM-->LMAN synapses 
      did not differ at hyper- versus depolarized holding potentials in adult males 
      that had completed the acquisition of a stereotyped song. This pattern indicates 
      that juvenile cells have a higher incidence of silent (NMDAR-only) synapses, 
      which are postsynaptically silent at hyperpolarized potentials due to the 
      voltage-dependent gating of NMDARs. Thus the decreased involvement of the LMAN 
      pathway in vocal behavior is mirrored by a decline in the incidence of silent 
      synapses but not by changes in the relative number of NMDA and AMPA receptors at 
      DLM-->LMAN synapses. These findings suggest that a developmental decrease in 
      silent synapses within LMAN may represent a neural correlate of behavioral 
      plasticity during song learning.
FAU - Bottjer, Sarah W
AU  - Bottjer SW
AD  - Program in Neuroscience, University of Southern California, Los Angeles, 90089, 
      USA. bottjer@usc.edu
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20050817
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
RN  - 0 (Excitatory Amino Acid Agonists)
RN  - 0 (Excitatory Amino Acid Antagonists)
RN  - 0 (Quinoxalines)
RN  - 118876-58-7 (2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline)
RN  - 6384-92-5 (N-Methylaspartate)
RN  - 77521-29-0 (alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid)
RN  - G6D6147J22 (biocytin)
RN  - K3Z4F929H6 (Lysine)
SB  - IM
MH  - Age Factors
MH  - Animals
MH  - Behavior, Animal
MH  - Cerebral Cortex/cytology/growth & development/*physiology
MH  - Dose-Response Relationship, Radiation
MH  - Electric Stimulation/methods
MH  - Excitatory Amino Acid Agonists/pharmacology
MH  - Excitatory Amino Acid Antagonists/pharmacology
MH  - Excitatory Postsynaptic Potentials/drug effects/physiology/radiation effects
MH  - Finches/physiology
MH  - In Vitro Techniques
MH  - Learning/*physiology
MH  - Lysine/analogs & derivatives/metabolism
MH  - Membrane Potentials/drug effects/physiology/radiation effects
MH  - N-Methylaspartate/pharmacology
MH  - Nerve Net/cytology/growth & development/*physiology
MH  - Neural Networks, Computer
MH  - Patch-Clamp Techniques/methods
MH  - Quinoxalines/pharmacology
MH  - Synapses/drug effects/*physiology
MH  - Thalamus/cytology/growth & development/*physiology
MH  - Vocalization, Animal/*physiology
MH  - alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
EDAT- 2005/08/19 09:00
MHDA- 2006/01/26 09:00
CRDT- 2005/08/19 09:00
PHST- 2005/08/19 09:00 [pubmed]
PHST- 2006/01/26 09:00 [medline]
PHST- 2005/08/19 09:00 [entrez]
AID - 00282.2005 [pii]
AID - 10.1152/jn.00282.2005 [doi]
PST - ppublish
SO  - J Neurophysiol. 2005 Dec;94(6):3698-707. doi: 10.1152/jn.00282.2005. Epub 2005 
      Aug 17.