Selective deficits in reversal learning after neostriatum caudolaterale lesions in pigeons: possible behavioral equivalencies to the mammalian prefrontal system.

The neostriatum caudolaterale (NCL) of birds is thought to be equivalent to the mammalian prefrontal cortex (PFC) due to its dense dopaminergic innervation, its associative structure, and its importance for cognitive tasks which are known to be affected in mammals with prefrontal lesions. The aim of the present study was to analyze the functional importance of the NCL and its main thalamic afferent structure, the n. dorsolateralis posterior thalami (DLP), in reversal and go/no-go tasks, two behavioral procedures which are often used to assess mammalian prefrontal functions. Using a multiple regression analysis in which structure-specific lesion extents are correlated with different postoperative behavioral measures, the specific contribution of the relevant structures were differentiated from the neighbouring areas CDL (area corticoidea dorsolateralis) and NC (neostriatum caudale). The analyses showed a highly significant contribution of the NCL to reversal but not to go/no-go or to visual discrimination performance, while all other structures under analysis had no impact on any behavioral measure. These results underline the specific contribution of the pigeons' NCL on a subset of cognitive tasks which are known to be affected by prefrontal lesions in mammals.