TY - JOUR
T1 - Delayed-onset sensitization emerges after dishabituation in developing Aplysia
AU - Wright, William G.
AU - McCance, Elizabeth F.
AU - Theresa, Lu
AU - Carew, Thomas J.
N1 - Funding Information:
The surprising delay in the onset of sensitization observed by Marcus et al. (1988) motivated the present study. In the studies by Rankin and Carew (1987, 1988) examining the developmental emergence of sensitization, the siphon withdrawal reflex was tested during the 10 min following tail shock. Thus, it was not determined in those studies whether juvenile animals, like adults, exhibit a de- was supported by NSF grant BNS 8614961 and ONR grant N00014-87-K-0381 to T.J.C. All correspondence and reprint requests should be addressed to Thomas J. Carew, Dept. of Psychology, Yale University, P.O. Box llA Yale Station, New Haven, CT 06520.
PY - 1992/3
Y1 - 1992/3
N2 - A recent study of the development of nonassociative learning in the siphon withdrawal reflex of Aplysia showed that dishabituation (facilitation of an habituated response) and sensitization (facilitation of a nonhabituated response) emerge according to different developmental timetables: dishabituation precedes sensitization by approximately 60 days (Rankin & Carew, 1988). Both forms of facilitation of the reflex were observed within 90 s of an electrical shock to the tail. However, more recent work by Marcus and colleagues (1988) in adult animals revealed that sensitization can have a delayed onset of 20-30 min after a strong tail shock. Since the developmental study of Rankin and Carew (1988) only tested the reflex for 10 min after tail shock, it is possible that sensitization was in fact present at earlier developmental stages, but was undetected. To examine this question, in the present study we utilized a longer (40-50 min) post-shock observation period to determine whether delayed-onset sensitization is exhibited in juvenile Aplysia, and if so, when it is expressed during development. In our first experiment, we found that Early Stage 12 juveniles (80-95 days after metamorphosis) showed significant delayed-onset sensitization 30-50 min after a strong tail shock. In a second experiment, we found that delayed-onset sensitization was absent in Stage 11 animals (20-70 days after metamorphosis). Thus delayed-onset sensitization emerges in Early Stage 12. The fact that the birthdate of delayed-onset sensitization is at least 30 days after that of dishabituation (Rankin & Carew, 1987, 1988) supports the hypothesis that these two forms of nonassociative learning may have at least partly different underlying mechanisms.
AB - A recent study of the development of nonassociative learning in the siphon withdrawal reflex of Aplysia showed that dishabituation (facilitation of an habituated response) and sensitization (facilitation of a nonhabituated response) emerge according to different developmental timetables: dishabituation precedes sensitization by approximately 60 days (Rankin & Carew, 1988). Both forms of facilitation of the reflex were observed within 90 s of an electrical shock to the tail. However, more recent work by Marcus and colleagues (1988) in adult animals revealed that sensitization can have a delayed onset of 20-30 min after a strong tail shock. Since the developmental study of Rankin and Carew (1988) only tested the reflex for 10 min after tail shock, it is possible that sensitization was in fact present at earlier developmental stages, but was undetected. To examine this question, in the present study we utilized a longer (40-50 min) post-shock observation period to determine whether delayed-onset sensitization is exhibited in juvenile Aplysia, and if so, when it is expressed during development. In our first experiment, we found that Early Stage 12 juveniles (80-95 days after metamorphosis) showed significant delayed-onset sensitization 30-50 min after a strong tail shock. In a second experiment, we found that delayed-onset sensitization was absent in Stage 11 animals (20-70 days after metamorphosis). Thus delayed-onset sensitization emerges in Early Stage 12. The fact that the birthdate of delayed-onset sensitization is at least 30 days after that of dishabituation (Rankin & Carew, 1987, 1988) supports the hypothesis that these two forms of nonassociative learning may have at least partly different underlying mechanisms.
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U2 - 10.1016/0163-1047(92)90689-2
DO - 10.1016/0163-1047(92)90689-2
M3 - Article
C2 - 1586356
AN - SCOPUS:0026608028
SN - 0163-1047
VL - 57
SP - 170
EP - 174
JO - Behavioral and Neural Biology
JF - Behavioral and Neural Biology
IS - 2
ER -