Transfer of information with brain extracts from donors to recipients in passive-avoidance behavior

Experiments were conducted in a step-through, one-trail, passive-avoidance situation, in order to study the effect of crude or 10,000 dalton-ultrafiltered brain extracts, from trained donor rats, on the learning of the same behavior in naive or undertrained recipient rats. A positive transfer effect was consistently detectable in the latter, apparently related to consolidated learning, but not to the level of avoidance performance or of general activation in the donors. Temporal and cognitive requirements, for such an effect to occur, have been established with regard to donor-training and recipient-managing procedures. A tentative explanation of the transfer effect in the passive-avoidance behavior cannot disregard the possibility of material transmission of information pertaining to a response elicited by primary or secondary reinforcement. Such a response, although quite distinct from the somatomotor response, would be necessary to its acquisition but not to its expression.