Arthur Leblois

David J Perkel

BMC Neuroscience

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BioMed Central
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BMC Neuroscience
Open AccessOral presentation
Local inhibition shapes afferent excitatory drive of output neurons 
in the songbird basal ganglia network
Arthur Leblois*1 and David J Perkel1,2
Address: 1Department of Biology, University of Washington, Seattle, WA 98195, USA and 2Department of Otolaryngology, University of 
Washington, Seattle, WA 98195, USA
Email: Arthur Leblois* - aleblois@u.washington.edu
* Corresponding author    
Background
Song learning in songbirds shares striking similarities
with speech acquisition in humans. Songbird brains con-
tain a neural network dedicated to song learning, called
the anterior forebrain pathway, which is homologous to
the mammalian basal ganglia (BG)-thalamo-cortical
loop. A structure called Area X contains both striatal and
pallidal components of the BG circuit and projects to the
medial portion of the dorsolateral nucleus of the thala-
mus (DLM), where pallidal cells make powerful GABAer-
gic synapses that could drive firing through post-
inhibitory rebound mechanisms. We aim to determine
the transformation undergone by input signals through
avian BG.
Methods
We recorded the extracellular activity of i) Area X pallidal
neurons and ii) DLM neurons in response to electrical
stimulation of Area X afferent structures, namely HVC
(used as a proper name) and the lateral magnocellular
nucleus of the anterior nidopallium (LMAN). Recordings
were made from adult male zebra finches, either in ure-
thane-anesthetized in vivo preparation or in brain slices.
Results
In vivo, almost all pallidal neurons of Area X displayed a
rapid excitation in response to stimulation in either HVC
(n = 48) or LMAN (n = 20). The excitation was often fol-
lowed and/or, surprisingly, preceded by inhibition. The
resulting excitatory peak in these responses was very short.
Its average latency was 11.6 ms (n = 44), and its duration
was 8.8 ms, while average inhibition latency was 10.4 ms
(n = 26). We found no difference between the effect of
stimulating HVC vs LMAN. We also found through antid-
romic stimulation that most Area X pallidal cells project to
DLM (7/11), and that the giant terminals of these cells
recorded in DLM (n = 17) displayed responses similar to
those of other pallidal cell somata recorded within Area X
(n = 31). After application of the GABAA receptor blocker
picrotoxin in Area X, inhibitory components of the palli-
dal responses were absent and the excitatory component
became longer, with an average duration of 17 ms (n =
10). In vitro recordings confirmed that pallidal responses
to HVC fibers stimulation are broadened by picrotoxin
application. In DLM neurons in vivo, HVC stimulation
evoked rapid and precise excitatory responses, with an
average latency of 17.8 ms (n = 12).
Conclusion
Afferent fiber stimulation evokes a short excitatory
response in pallidal cells, which is shaped by an inhibi-
tory network in Area X. This response profile could play
various roles in driving firing in DLM, either providing a
strong inhibition allowing subsequent post-inhibitory
rebound, or shortening rebound firing induced by a pre-
vious pause.
from Seventeenth Annual Computational Neuroscience Meeting: CNS*2008
Portland, OR, USA. 19–24 July 2008
Published: 11 July 2008
BMC Neuroscience 2008, 9(Suppl 1):O6 doi:10.1186/1471-2202-9-S1-O6
This abstract is available from: http://www.biomedcentral.com/1471-2202/9/S1/O6
© 2008 Leblois and Perkel; licensee BioMed Central Ltd. 


Local inhibition shapes afferent excitatory drive of output neurons in the songbird basal ganglia network

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Local inhibition shapes afferent excitatory drive of output neurons in the songbird basal ganglia network

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