An Inexpensive Habituation and Sensitization Learning Laboratory Exercise Using Planarians

Abstract

We dasnik an inexpensiw 1abnmtor)r exerci.ie thar lcres pla. mrians to demonstrate habitunrion and scnsitizaticm. Students drop waterfrom an eyedropper onto a plonarian's anteriw re@ and observe its contraction respaues. Initially. studenti practice the pmcedure until atmining high interobserver reliahilitv in scming the degree of contraction. Subsequently, rhey measure the decline in responciviry that occurs over repeated stimulus presentation~. Fcrllowing Imbin.mtion, the planarion is d r a m in and otir of the eyedropper sewerr11 rimes, resultine in sensitization and dishabituation of the contractile respnnie in accordance with drralprocess theory (Gmues FP Thompson, 1970). This ~~rucedure can also k used to demonstrate spontaneous recovq und shortw s u s long-term habituation processes.Difficulties associated with demonstrating fundamental learning processes to large groups of students without large costs have inspired many ingenious lahoratory exercises requiring simple equipment. O n e successful apprrrach uses planarians (e.g., Dugesia drmrtocephla) as experimental suhjects. As Katr (1978) noted, planarians occupy a unique position in evolutionary history as the earliest hilaterally symmetricanimals. Thesesimple, aquatic, invertebrate flatwornis evince synaptic nerve cunduction and are capahle of learning. Planarians are small ( I to 2 cm long), nonthreatening to students, inexpensive, and easy to care for (see Kenk, 1967). Descriptions of planarian anatomy (e.g..Pearse. Pearse, Buchshaum, & Buchsbaum, 1987;Stachowitsch, 1992) and behavioral hiology (e.g., Jenkins, 1967) are readily availahle. These animals exhibit habituation. classical conditioning, and instrumental condirinning (reviewed hyComing&Kelly, 1973). Descriptionsirfplanarianbased lahoratory exercises for educarional settin~s are available for classical and instruniental conditioning ( r . g . , Ahramson, 1990; Karz, 1978) but not for hahituarion and rensitiiation. The latter phenomena can he shown using other invertebrates (e.#., Ahramsc~n, 19YO), hut rhe specialized equipment required may make such exercises impracticable with large grnups nf srudents.This article extends the literature concerning the use of planarians in the undergraduate learning lahoratory to include the pnrcesses of hahituation and sensitization. As defined hy Groves and Thompson (19701, hahitvation refers to the decrease in resprnsiveness to a stin~ulus thar can occur as a result of repeated exposure to char stimulus. Conversely, sensitization refers to an increase in resplnsivenessas a restilt of stimulation. Groves and Thompson's dual-pn~cess theory proposed that hahituation is the simplest form of true leaming, resulting from experience-hased changes in a specific stimulus-response system. Sensitization, in contrast, was hypothesized to result from state changes in a central arousal system that does nc)t reflect a learning process.A planarian swimming in a Petri dish initially exhihits a reflexive contraction response when a water droplet is released onto or near its...

Use of Terrestrial Hermit Crabs in the Study of Habituation

“…This behavior is easy to observe and subject to habituation (Abramson, 1994). In addition, the crabs are large and more physically robust than planaria (Owren & Scheuneman, 1993), which I have found not to survive repeated stimulation by students.…”

Short- and long-term habituation of photonegative and exploratory responses in the flatworm planaria (Dugesia).

“…Despite the popularity of a habituation preparation in planarians (e.g., Owren & Scheuneman, 1993), near to no attention has been paid to its temporal course. The only study that addressed the effect of repeated presentations of an eliciting stimulus over several days and tested the animals reactivity to the stimulus after an interval of at least 24 hr is that reported by Westerman more than 50 years ago (Westerman, 1963).…”

“…Other studies showed that animals’ natural responses to vibration (Dilk, 1937) and changes in luminance (Miller & Mahaffy, 1930) readily habituated. The habituation of the longitudinal contraction in response to a drop of water on the body of the animal has been widely used to demonstrate short-term habituation in the planaria; this observation has become a popular high-school lab demonstration (see, e.g., Owren & Scheuneman, 1993).…”

“A Super Wild Story”: Shared Human–Pigeon Lives and the Questions They Beg

“…Habituation seems to function as a concept that describes and directs attention to processes of normalization, accustomation, and the resulting smoothing over of differences. In existing conceptualizations of shared human-animal lives (excluding conventional pets or companion animals), habituation is used to explain a process through which one species becomes accustomed to another's presence, usually a nonhuman animal to a human animal (Candea, 2010;Clay, Bloomsmith, Marr, & Maple, 2009), but it also extends to explaining general processes of accustomation of species such as hamsters (Johnston, 1993) or even flatworms (Owren & Scheuneman, 1993).…”