behavioral plasticity CH8: development of learning in songbirds behavioral analysis of birdsong

1. PART 4: BEHAVIORAL PLASTICITY #16: DEVELOPMENT OF LEARNING IN SONGBIRDS I • behavioral plasticity • CH8: development of learning in songbirds • behavioral analysis of birdsong • singing in the brain • summary

2. PART 4: BEHAVIORAL PLASTICITY #16: DEVELOPMENT OF LEARNING IN SONGBIRDS I • behavioral plasticity • CH8: development of learning in songbirds • behavioral analysis of birdsong • singing in the brain • summary

3. BEHAVIORAL PLASTICITY • adaptive responses to repeated experiences • experience  prediction of future events • information learned, stored & later retrieved • many forms, simple & complex • experiences via all sensory modalities • encoded in nervous system • cellular machinery • neuronal networks • behavioral plasticity ~ neural plasticity • nature - nurture

4. DEVELOPMENT OF LEARNING IN SONGBIRDS • vocal communication • territory • warning • breeding • ? • highly diverse songs • studied to learn about • how animals communicate • learning & memory

5. DEVELOPMENT OF LEARNING IN SONGBIRDS • birds • 28 orders, 163 families, < 2000 genera, ~ 9000 spp. • ~ 4000 songbird spp. • most work on song done with 3 spp. • white-crowned sparrow (Zonotrichia leucophrys) • zebra finch (Poephia guttata) • canary (Serinus canaria)

6. DEVELOPMENT OF LEARNING IN SONGBIRDS • song • mostly on perches (not ground)... more effective • rich in sp.-specific & social information • huge variety among bird spp. • 1 invariant song • ~ 100 songs • geographic dialects • learning... for many spp. • must hear sp.-specific song @ critical time • normal development, under hormonal control

7. BEHAVIORAL ANALYSIS • systematics of birdsong began early (Darwin) • lab studies in 1950s • methodology • framed important questions

8. WHAT’S IN A SONG ? • accoustic structure • time-frequency sound spectrograph  visualize • song consists of punctuated sound units • note or element = 1 continuous sound • can have varied internal structure • syllable  2 notes • phrase  2 syllables or • can be 1 syllable / note @ critical position • syntax = timing, order,  song specificity

9. WHAT’S IN A SONG ? • accoustic structure

10. WHAT’S IN A SONG ? • dialects (eg., white crowned sparrow) • same song, different location

11. WHAT’S IN A SONG ? • vocalization mechanism • respiration-driven... breathe between syllables • sound from syrinx (~ human larynx) • vibration of syringeal tympaniform membranes

12. SONG LEARNING • in many spp. only sing • initial studies (chaffinch) • isolated young s • played tapes of adult  song • observed that young s • could imitate recording of species-typical song • no exposure  songs very simple • exposure as adult  songs abnormal •  learning by imitation @ specific age • some birds (eg., canaries) not age-limited • open-ended learners

13. SONG LEARNING • stages of song learning • similar in most songbirds • temporal variation • 1st, make subsong • ~ baby talk • part of development, only in spp. that learn • 2nd, make plastic song • 1st evidence of imitation & song rehearsal • sp.-specific characteristics recognizable

14. SONG LEARNING • timing of learning, different phases, can overlap • sensory: critical / sensitive, must hear song • sensorimotor: subsong & plastic song phases • crystalized: song fully developed

15. SONG LEARNING • duration & timing of phases varies • age-limited learners (B), phases can overlap

16. SONG LEARNING • duration & timing of phases varies • age-limited learners (B), phases can overlap • seasonal-closed learners (A), phases separated

17. may only learn as juveniles & recall... SONG LEARNING • duration & timing of phases varies • age-limited learners (B), phases can overlap • seasonal-closed learners (A), phases separated • open-ended learners (C), overlap & repeat

18. SONG LEARNING • timing differences within same species, related to • length of breeding season • probably triggered by photoperiod

19. critical period ~ 65 days in presence of  father • > 65 days in presence of s SONG LEARNING • what closes the learning-critical time window ? • in Zebra finches...

20. SONG LEARNING • what closes the learning-critical time window ? • critical period in Zebra finches... • ~ 65 days in presence of  father • > 65 days in presence of s • influence of tutors... live > taped • not fixed time window • social interaction & tutor variation influence • sensitive rather than critical windowflexibility

21. SONG LEARNING • imitation, improvisation & invention • not purely imitation of  father • swamp sparrows ~ 200 syllables • 1/3 imitated • 36 improvised (variations) • > 1/3 invented (novel) • imitated 1st improvised & invented later

22. SONG LEARNING • imitation, improvisation & invention • creative process, can combine multiple songs

23. SONG LEARNING • imitation, improvisation & invention • crystalized song is subset of plastic song syllables • trial & error use ? • action-based learning • some birds may sing songs in the order they were learned

24. SONG LEARNING • what is learned during sensory phase ? • studied with play-back of taped or synthetic songs • innate preferences • species-specific > other

25. SONG LEARNING • what is learned during sensory phase ? • studied with play-back of taped or synthetic songs • innate preferences • sp.-specific > other song • live non-specific > taped sp.-specific song • non-specific father > live sp.-specific song but with no visual... multimodal sensory critical – context • sp.-specific > non-specific  physiological response (eg., heart rate) – internal mechanism • use innate + learned / experienced information

26. SONG LEARNING • learning a foreign song... what is not innate • eg., sympatric sparrows, many song differences • normal • isolated • tape-trained • deaf

27. SONG LEARNING • learning a foreign song... what is not innate • tape-trained... sp. specific > non • mixed taped songs: • swamp sparrows used ~ syllable phonology • song sparrows used syllable phonology, syntax & song tempo... could learn • swamp sparrow songs in their own syntax • own syllables in swamp sparrow pattern • but not normal swamp sparrow song •  hear, articulate but use perceptual filter

28. SONG LEARNING • innate song... what is not learned • isolated birds • sing abnormal songs • some sing recognizable isolate or innate songs • eg., swamp sparrow • can also learn rest of song •  isolation not  learning

29. SONG LEARNING • innate song... what is not learned • aspects of innate songs develop normally > others • duration, tonality, frequency range OK • syllables (words!) NOT •  certain aspects of song innate, others learned • repertoire size (# of songs) innate

30. no song memory at all • very different song from SONG LEARNING • auditory feedback & song templates • how does singing begin in sensorimotor phase ? • feedback ?... test by deafening (remove cochlea) • before subsong... tutoring does not work • accesses own memory through hearing •  auditory feedback critical • isolated & deafened birds • song template matching • either innate or learned ! (... what... where... ?)

31. SONG LEARNING • auditory feedback & song templates • feedback ?... • initially thought not critical for song maintenance • deafening after crystallization • no effect ?... • after some time •  syllables • phonology of syllables changes •  can be critical for development & maintenance

32. SEXUAL DIMORPHISM & HORMONAL REGULATION • in most songbirds... only s sing, sexual dimorphism • neuronal basis of song ~ brain polymorphism ? • in (eg., canaries)hormone levels correlated with • breeding season • gonad size • song, 1/~ new syllables • castrated s do not learn complete song

33. SEXUAL DIMORPHISM & HORMONAL REGULATION • steroid hormonal control • s, stimulate song ~ s,  repertoire • castrated s, retarded song development • + hormone  crystallizes song • – hormone  loss of crystallized song

34. SEXUAL DIMORPHISM & HORMONAL REGULATION • responses to hormonal treatment variable across spp. • development of language learning in birds ~ humans • critical time windows • stages • dependent on auditory feedback

35. BREAK