Basal ganglia preferentially encode context dependent choice in a two-armed bandit task
Front. Syst. Neurosci.. 2011-01-01; 5:
DOI: 10.3389/fnsys.2011.00023
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Garenne A(1), Pasquereau B, Guthrie M, Bioulac B, Boraud T.
Author information:
(1)Université de Bordeaux, UMR 5293, Institut des Maladies Neurodégénératives
Bordeaux, France.
Decision is a self-generated phenomenon, which is hard to track with standard
time averaging methods, such as peri-event time histograms (PETHs), used in
behaving animals. Reasons include variability in duration of events within a
task and uneven reaction time of animals. We have developed a temporal
normalization method where PETHs were juxtaposed all along task events and
compared between neurons. We applied this method to neurons recorded in striatum
and GPi of behaving monkeys involved in a choice task. We observed a
significantly higher homogeneity of neuron activity profile distributions in GPi
than in striatum. Focusing on the period of the task during which the decision
was taken, we showed that approximately one quarter of all recorded neurons
exhibited tuning functions. These so-called coding neurons had average firing
rates that varied as a function of the value of both presented cues, a
combination here referred to as context, and/or value of the chosen cue. The
tuning functions were used to build a simple maximum likelihood estimation
model, which revealed that (i) GPi neurons are more efficient at encoding both
choice and context than striatal neurons and (ii) context prediction rates were
higher than those for choice. Furthermore, the mutual information between choice
or context values and decision period average firing rate was higher in GPi than
in striatum. Considered together, these results suggest a convergence process of
the global information flow between striatum and GPi, preferentially involving
context encoding, which could be used by the network to perform decision-making.
DOI: 10.3389/fnsys.2011.00023
PMCID: PMC3093056
PMID: 21602915