Birdsong

Question 1

Song learning - how is it related to humans?

Answer 1

Closest analogy to language learning in humans (model system)

Question 2

Note

Answer 2

The most basic unit of song

Question 3

Syllable

Answer 3

Two or more notes

Question 4

Phrase

Answer 4

Groups of syllables (can consist of a single note or syllable)

Question 5

Syntax

Answer 5

Specific timing and ordering of notes, syllables, and phrases

Question 6

Structures for coordinating singing w/ respiration

Answer 6

Air sacs provide air while singing
Vocal organ (syrinx) - bronchial rings bring in air while singing
Tympaniform membranes vibrate when sounds are produced

Question 7

Experiments by Thorpe in song learning

Answer 7

Young chaffinches were isolated and taped songs were played → if isolated birds were not exposed to tutoring/were exposed after sexual maturity, songs that developed were oversimplified and abnormal

Question 8

Timeline of song learning

Answer 8

1. Sub-song - variable in timing and pattern (similar to babbling)
2. Plastic song - similar to adult song, duration of song and composite syllables are varied
3. Crystallized song - adult song

Question 9

Important phases of song development

Answer 9

1. Sensory phase - exposure to song (critical period)
2. Sensory-motor phase - sub-song, plastic song (no exposure to song during this)
   NOT THE SAME TIME COURSE FOR ALL BIRDS: seasonal breeders have separate phases (i.e. white-crowned sparrow), year-round breeders have overlapping phases (i.e. zebra finch)

Question 10

Differences in phases of song acquisition across different birds

Answer 10

White-crowned sparrows (seasonal closed learners) - critical period ends after sensory phase and before sensory-motor phase
Zebra finches (age-limited learners) - critical period closes after sensory-motor phase has started
Canaries (open-ended learners) - can learn new songs (no end of critical period), sensory phase potentially restarts when crystallized song happens

Question 11

Timing of different stages within the same species

Answer 11

Coastal - plastic song onset starts sooner, overlap between phases
Montane - plastic song onset starts later, very distinct phases (no overlap)
Innate and environmental components

Question 12

Creativity in song production

Answer 12

Crystallized songs of young birds include some improvisation (can be almost identical to tutor, depends on # of tutors)

Question 13

Songs involve learning + genes

Answer 13

Birds that are isolated but untrained → similar # of elements to adult song, similar syntactic and phonemic structure
Birds that are isolated and trained → similar to adult song
Birds that are deafened before subsong stage → disrupted production of song

Question 14

Major principles of song learning

Answer 14

1. Learning from a tutor - vocal learning
2. Critical period
3. Important hypothesis - template matching

Question 15

Template matching

Answer 15

Ear → brain → vocal organ → template of song → back to ear (feedback provided in this model via external song)

Question 16

Neural pathways in the birdsong system - song production (motor)

Answer 16

HVc - higher vocal center
RA - robust nucleus of the archistratum
nXIIts - hypoglossal nucleus

Question 17

Neural pathways in the birdsong system - song learning (sensory)

Answer 17

Area X
DLM - m dorsolateral thalamus
LMAN - L magnocellular n. of anterior neostriatum

Question 18

Neural correlates of song production - HVc contribution

Answer 18

HVc neurons active prior to RA neurons → hierarchical processing
HVc neurons contribute to fine temporal structure within syllables

Question 19

Michael Long experiment with HVc neurons

Answer 19

Particular area involved in controlling song timing → cooling that area should slow the song (timing between syllables is increased when HVc is cooled → song is stretched out)

Question 20

Experiment to determine role of RA

Answer 20

Temperature of RA is manipulated → no impact on fine temporal structure of song

Question 21

Role of LMAN

Answer 21

Lesions of LMAN in juvenile zebra finches caused severe deficits in song (adult zebra finches produce crystallized songs normally but cannot display context-dependent changes in variability and do not deteriorate following deafening) → LMAN contributes to learning of song

Question 22

Interactions between LMAN, RA, and HVc

Answer 22

Electrical stimulation of LMAN (not HVc) evoked excitatory synaptic potentials from virtually all RA neurons in brain slices prepared from male & female zebra finches less than 25 days in age → HVc and LMAN interact in RA

Question 23

Role of error signals in singing

Answer 23

LMAN brings in auditory feedback-related info, HVc brings in motor output for singing → RA compares and generates error signal (good match = small signal)

Question 24

Role of error signals in learning

Answer 24

Songbirds use auditory feedback to learn to sing and have a dopaminergic projection from VTA to Area X (a nucleus required for song learning) → auditory error-based reinforcement signal is computed, tells vocal motor circuits if recent vocalization was “good” or “bad”

Question 25

Experiment to determine the role of dopamine

Answer 25

Recorded from VTA while playing a distorted song → dopamine activity was phasically suppressed after distorted syllables (worse-than-predicted outcome), was phasically activated at the precise moment of the song when a predicted distortion did not occur (better-than-predicted outcome)