Platyhelminthes: The Turbellarians

Attempts to retreat from a dead-ended long capillary by backward swimming in Paramecium

“…In terms of conventional ethology, associative learning and memory might be expressed as operants and the formation of new behaviors. Although past studies have attempted to demonstrate operant conditioning in protozoa (Corning et al, 1973; Eisenstein, 1975), few have been successful when considering criteria established from animal research. But we anticipate the ethological significance of LBS will encourage constructive studies on the mechanisms of behavioral evolution, such as adaption or learning processes, and on the cytological physiochemical processes that may underlie them.…”

“…One of the most important issues to be addressed here is what types of behavior can be induced and how such behavioral options appear in terms of information processing in the cell. It is interesting to identify whether mechanisms of information processing are based on mechanical equations of motion, because in some sense the physical basis of an adaptation or learning process could be suggested (Corning et al, 1973; Bray, 2009). …”

Alternatives to Animal Use in Research

“…Flatworms are also of considerable interest, since they represent a bilateral body form, as do mammals. Flatworms exhibit a concentration of nervous tissue and sensory organs in the anterior, or head, portion of their bodies, and they have refined internal organ systems (47). Flatworms exhibit habituation, can be conditioned to avoid alight after it has been paired with shock, and can learn to approach an area for food reward.…”

“…There are also claims that such learned events are remembered after these worms undergo regeneration, and that learning can be transferred from one animal to another by cannibalism (reviewed in ref. 47).…”

Primitive nervous systems: Peripheral habituation in decerebrate polyclad flatworms

“…Despite considerable interest in and controversy concerning learning in planarians, there is surprisingly little hard data about plasticity within platyhelminth nervous systems. Nearly all information on this aspect of flatworm nervous systems has been deduced from behavioral observations (reviewed by Corning and Kelly, 1973), and hence can be subject to a variety of interpretations. Habituation, which is usually considered to be the simplest form of neurophysiological plasticity, has only been demonstrated a few times in flatworms.…”