Ensemble recordings in rat orbitofrontal cortex during olfactory discrimination
learning: Encoding of reward magnitude
E. van Duuren1,2, F.A. Nieto-Escámez1, R.N.J.M.A. Joosten1, R.
Visser1, A.B. Mulder1 and C.M.A. Pennartz2
1Netherlands Institute for
Brain Research, Amsterdam, The Netherlands
2SILS Center for Neuroscience, University of Amsterdam, Amsterdam, The
Netherlands
The orbitofrontal cortex (OBFc) is known to be involved in the encoding
of the motivational signi.cance of stimuli and in applying this information
to the guidance of goal-directed behavior, as well as in the encoding
of predictive information regarding upcoming reinforcers: neurons in the
OBFc show differential firing activity during the anticipation of appetitive
and aversive outcomes. To examine whether neurons in the OBFc are also
able to discriminate between different amounts of reinforcers ensemble
recordings were performed in rats engaged in associative learning during
an odor discrimination ‘go – no go’ task. In this task
animals learned to associate a particular odor stimulus with fluid reinforcement
of varying magnitude or sign and adjust their behavior accordingly. A
set of five different odors was used for any discrimination session: three
odors associated with a particular amount of a positive reinforcement
(10% sucrose solution, i.e. 0.05, 0.15 and 0.30 ml), one odor with no
reward (non- reinforced condition), and one odor associated with a negative
reinforcement (0.15 ml of a 0.015 M quinine solution). This task design
allows the examination of the encoding of both actual and expected reward
magnitude in the OBFc since reinforcements are preceded by the odors as
predictive stimuli.
Paper presented
at Measuring Behavior 2005
, 5th International Conference on Methods and Techniques
in Behavioral Research, 30 August - 2 September 2005, Wageningen, The
Netherlands.
© 2005 Noldus
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