RESEARCH Exposure to cues associate Background an important role in olfactory processing and integrating

1R6, Québec, CanadaDopaminergic projections to the entorhinal cortex are likely to play an important role in modulating the manner in which the entorhinal cortex contributes to sensory inte-gration and mnemonic processing. The entorhinal cortex provides the hippocampus with much of its cortical sen-sory input and is thought to play roles in sensory integra-tion, memory formation, and spatial navigation [1-4]. The lateral division of the entorhinal cortex receives heavy in-puts from primary olfactory cortex suggesting that it plays olfactory information with other sensory inputs [1,5], and it also receives a large projection from midbrain dopamine neurons [6-11]. Dopaminergic effects on neuronal excit-ability (e.g.s, [12,13]), and on synaptic transmission within the entorhinal cortex, are therefore likely to have import-ant effects on cognitive processes as animals engage in motivated behaviours associated with activation of dopa-mine neurons. Application of dopamine to acute brain slices in vitro generally results in a suppression of glutamate-mediated synaptic responses in neurons in the entorhinal cortex that is mediated by activation of D2 receptors [5,14-16]