Search PubMed⌕ Search

Biomedical subjects

J F Harrigan

Publications and source records attributed to J F Harrigan.

6 recordsLinked to original sources
PubMed1988

Sequential modification of membrane currents with classical conditioning.

Pavlovian conditioning of the nudibranch mollusc Hermissenda crassicornis was previously shown to produce long-lasting reduction of two K+ currents measured across the Type B photoreceptor soma membrane (Alkon et al., 1982a; Alkon et al., 1985). Pavlovian conditioning of the rabbit was also shown to be followed by persistent K+ current reduction (Disterhoft et al., 1986). Here we report the first evidence that Ca2+ currents can also be modified by conditioning. The amplitude of the currents rather than their voltage-dependence remains reduced at least 1-2 d after conditioning (but not control procedures). Conditioning-induced changes of both K+ and Ca2+ currents increased as a function of training, the Ca2+ currents only changing substantially with greater than or equal to 250 trials. The later changes of the Ca2+ current may function to limit the magnitude of excitability increases due to associative learning.

Animals↗
PubMed1984

Conditions of illumination during rearing affect specific components of phototactic behavior of laboratory-reared Hermissenda.

We have investigated the effect of 3 different conditions of illumination during rearing on phototactic behavior of the marine mollusk Hermissenda. Rearing Hermissenda in the dark results in a significant increase in the variability of positive phototactic behavior of adults and decreases responsiveness to illumination. The decrease in the positive phototactic response, as measured by the significant increase in the time taken by dark-reared Hermissenda to enter an illuminated area, was due to a decreased velocity of locomotion in the light gradient. These changes in phototactic behavior were not observed for Hermissenda reared on 12 h light-12 h dark cycles or under constant illumination. The affects of dark rearing on phototactic behavior cannot be the result of abnormal photoresponses since the photoreceptors of dark-reared Hermissenda exhibited normal generator potentials in response to light. A cellular analysis of the behavior of laboratory-reared Hermissenda will be useful in studying phototaxis since learning and experiences during rearing have two quite different behavioral consequences.

Animals↗