Chap.04 Learning 鄭先祐 (Ayo) 教授 國立台南大學 環境與生態學院 生態科學與技術學系 環境生態研究所 + 生態旅遊研究所

2 Learning  What is individual learning?  How animals learn  Why animals learn  What animals learn  Molecular genetics and endocrinology of learning  Phylogeny and the neurobiology of learning

3 Damselflies larvae learn about predation threat through chemical cues.

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5 What is individual learning?  Individual learning, to a relatively permanent change in behavior as a result of experience.  Phenotypic plasticity, an organism to produce different phenotypes depending on environmental conditions.  In some bryozoans, colonies produce spines when predators are present. (A) spines are shown protruding from a colony. (B) an overview of a colony (Fig. 4-3)

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7 When colonies of the bryozoan are exposed to chemical stimuli from a predator, individuals in these colonies grow defense spines.

8 How animals learn  Learning from a single-stimulus experience  Sensitization and habituation  Pavlovian (Classical) conditioning ( 情淨 化：制約 )  Instrumental (Operant) conditioning

9 Numerous times each day a blue stick is placed in a rat’s cage. If the rat takes less and less notice of the stick, habituation has occurred. If the rat pays more attention to the blue stick over time, sensitization has taken place.

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11 Ivan Pavlov and classical conditioning

12 Terms  CS = conditioned stimulus  US = unconditioned stimulus  CR = conditioned response  Appetitive stimulus ( 正向刺激 )  Aversive stimulus ( 負向刺激 )  Excitatory conditioning  Inhibitory conditioning

13 Cat odor

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16 Overshadowing and Blocking  Overshadowing–  if the red light is always presented simultaneously with the blue stick, just prior to the presence of the cat odor (fig. 4.11), rats (group 2) will respond less strongly to the blue stick.  Blocking –  Rats first learned to associate the blue stick and cat odor before any red light was added. Then they are presented with the stimulus to the red light. (Fig. 4.12)

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19  Operant conditioning, instrumental conditioning, goal-directed learning.  B. F. Skinner, Skinner boxes

20 Why animals learn  Within-species studies  Garcia ’ s rats (since the mid-1960) Cues, punishment, delay reinforcement  Optimal forgetting in bees and stomatopods( 口足目 )  Population comparisons  Group living in doves  Antipredator behavior in sticklebacks  A model of the evolution of learning

21 Imaging a bee foraging at a nectar-producing flower. While it might pay for the bee to remember the flower’s location, it might not be beneficial to remember specific nectar content, as that shifts within and between days.

22 Male and female stomatopod crustaceans share a cavity for a few days before they breed. Although the males leave the breeding cavity soon after mating, they tend to remember their former mates and to be less aggressive toward them during the weeks that their brood remains in the cavity. 蝦蛄

23 Population comparisons and the evolution of learning  Learning, foraging, and group living in doves.  Animals in groups often find food faster and have more time available for foraging Individuals who live in groups should learn more quickly than territorial individuals. Zenaida doves (Fig )  Learning and antipredator behavior in sticklebacks

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25 Fig. 4.17

26 Learning and antipredator behavior in sticklebacks  After a stickleback had learned that one side of its tank was associated with food, fish were subject to a simulated attack from a heron predator.  How long it took to learn to avoid the side of the tank associated with heron predation (and food) (Fig. 4.18)  Fish from high-predation areas learned this task more quickly than did fish from predator-free populations.

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28 Fig right

29 A model of the evolution of learning

30 What animals learn?  Learning where home is located  Juvenile salmon appear to learn the odors associated with their natal streams, and they subsequently use such information to guide their way home. (pink salmon migration, Fig. 4.19)  Learning about your mate  Learning about familial relationships  Learning about aggression

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32 Learning about your mate  Mongolian gerbils are burrowing desert rodents that rely on chemical communication during many forms of social exchange, including the formation of pair bonds.  Differences between males and females in their learning abilities should be positively correlated with differences in male and female parental investment.  Mongolian gerbils and gourami fish, parental investment is shared and learning differences between the sexes are small.  In Japanese quail, where there is no parental investment on the part of males, males show significantly greater learning abilities than do females (Fig. 4.20)

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34 Learning about familial relationships  Young reproductively active long-tialed tits breed independently as soon as they can. (Fig. 4.21) However, most nests fall victim to predation on the young.  Breeders often become helpers at the nests of their close genetic relatives, and such helpers accrue indirect fitness benefits by helping to raise their kin.  How do the birds know who are kin?  Play back experiment (Fig. 4.22)

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36 Individual birds showed a strong preference for the calls given by their close genetic kin, staying for a longer time near the speakers that gave off the calls of their kin.

37 Learning about aggression  Blue gouramis could be trained to associate a light with either the presence or absence of an intruder male in their territory. (Fig. 4.23)  Pavlovian learning  接受光訓練過的，打贏的機率較高，  且接下來，繼續打贏的機率也較高。 (Fig. 4.24)

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40 Molecular genetics and endocrinology of learning  Molecular genetics of learning in rats  More than forty years of breeding Syracuse High Avoidance (SHA) line –Avoided shocks in forty of sixty trails (average) Syracuse Low Avoidance (SLA) line –None of the sixty trails  Gene differences Velil,SLC3al, Ptpro, and Ykt6p showed greater expression in the hippocampus of SHA rats. SLC6A4/5HTT, Aldhla4, Id3a, and Cd74. greater in SLA rats.  Endocrinology of learning in rats

41 Endocrinology of learning in rats  Glucocorticoids (for example, Corticosterone) are hormones that play a large role in the stress responses and learning of many animals.  When pregnant female rats are stressed, and glucocorticoid levels rise, the offspring of such females show high levels of anxiety and perform sub-optimally in learning tests.  High-anxiety individuals took significantly longer than low-anxiety animals to learn to do so (water maze). (Fig. 4.25) High-anxiety animals had higher corticosterone levels than did low-anxiety animals

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44 Phylogeny and the neurobiology of learning  Phylogenetic work on learning is still in its infancy.  Innate versus learned behavior  Learning has been documented in many species of mollusks. In particular, snails in the family Aplysiidae have become a model system for studying the neurobiology of learning,  in large part because the nervous system of these snails contains only about 20,000 large and individually recognizable neurons that are grouped into about ten clusters.

45 Learning in snails  The sea hare, Aphysia californica, is the best studied of the snail species in which learning has been examined.  Serotonin appears to affect sensory neurons in two ways: (1) serotonin causes an increase in the duration of the electrical signal that travels along the axon, (2) serotonin increases the number of action potentials that are fired

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