(Holger Stark)

Mongolian gerbils learn fast to avoid a mild electric footshock in a shuttle-box (figure) by acquisition of avoidance or discrimination strategies. Learning processes cover different stages. The recorded learning behavior is compared with physiological data like the prefrontal dopamine, measured by microdialysis. The formation of essential associations as a prerequisite of successfully learning to avoid a footshock evokes a latent strong increase of dopamine metabolism in medial prefrontal cortex. The recording of the encephalogram (EEG) during training and the subsequent determination of theta synchronization allow the differentiation of stages in the development of the avoidance strategy of gerbils. Special events within single tone-shock-combinations during avoidance conditioning separate the stages (1) „signal detection“, (2) „escape learning“, (3) avoidance learning“, and (4) „retrieval of acquired avoidance strategy“ from one trial to the other. The high theta activation at the start of conditioning, which may reflect a strong demand of information processing by the animal, attenuates during maturation of the avoidance strategy. The detailed knowledge about the establishment of behavioral strategies will probably be useful for investigating cognitive functions like short term memory, feedback learning, error processing, planning, and decision making.

Figure:
While the gerbil learns the meaning of auditory stimuli and the appropriate behaviour in the shuttle-box, we measure the release of dopamine in its prefrontal cortex by microdialysis.

Co-worker:

Dr. Thomas Rothe

Collaborations:

Matthijs G. P. Feenstra (Institute for Brain Research, Amsterdam, The Netherlands)

Key publications

1. Stark, H. and Scheich, H. (1997) Dopaminergic and serotonergic neurotransmission systems are differentially involved in auditory cortex learning: a long-term microdialysis study of metabolites. J.Neurochem. 68 , 691-697.
2. Stark, H., Bischof, A. and Scheich, H. (1999) Increase of extracellular dopamine in prefrontal cortex of gerbils during acquisition of the avoidance strategy in the shuttle-box. Neurosci.Lett. 264 , 77-80.
3. Bischof, A., Stark, H., Wagner, T. and Scheich, H. (2000) The inhibitory influence of an acquired escape strategy on subsequent avoidance learning in gerbils. Neurosci.Lett. 281 , 175-178.
4. Stark, H., Bischof, A., Wagner, T. and Scheich, H. (2000) Stages of avoidance strategy formation in gerbils are correlated with dopaminergic transmission activity. Eur.J.Pharmacol. 405 , 263-275.
5. Bischof, A., Stark, H., Blumenstein, R., Wagner, T., Brechmann, A. and Scheich, H. (2001) A semiautomatic method for adding behavioral data to videotape records in combination with the Noldus Observer system. Behav.Res.Methods Instrum.Comput. 33 , 549-555.
6. Stark, H., Bischof, A., Wagner, T. and Scheich, H. (2001) Activation of the dopaminergic system of medial prefrontal cortex of gerbils during formation of relevant associations for the avoidance strategy in the shuttle-box. Prog.Neuropsychopharmacol.Biol.Psychiatry 25 , 409-426.
7. Stark, H., Rothe, T., Wagner, T. and Scheich, H. (2004) Learning a new behavioral strategy in the shuttle-box increases prefrontal dopamine. Neuroscience 126 , 21-29.
8. Stark, H., Rothe, T., Deliano, M. and Scheich, H. (2007) Theta activity attenuation correlates with avoidance learning progress in gerbils. NeuroReport 18 , 549-552.
9. Stark, H., Rothe, T., Deliano, M. and Scheich, H. (2008) Dynamics of cortical theta activity correlates with stages of auditory avoidance strategy formation in a shuttle-box. Neuroscience 151 , 467-475.