Response habituation in the superficial layers of the guinea-pig superior colliculus in vitro.

Response habituation (RH) has been suggested to reflect the role of the mammalian superior colliculus (SC) as a novelty detector. In the present study, we show that RH occurs in the SC slice preparation and is caused partially by the activation of inhibitory GABA receptors. No evidence for the contribution of presynaptic transmitter release was found and the block of N-methyl-D-aspartate (NMDA) receptors facilitated RH for a higher stimulation frequency. Since RH could not be abolished completely by any treatment, it appears that other mechanisms such as a general metabolic fatigue may contribute to RH. Nevertheless, RH must be taken into account when performing repeated stimulation in the SC slice preparation.