Birds’ song variability is modulated by LMAN

in anterior forebrain pathway

Hugo Trad & Stephen Larroque

19 Nov 2015

Learning to sing

• Birds’ singing is a complex, learnt task

• Uses cortical-basal ganglia circuit

• Different song characteristics between directed (couple) and undirected (single)

• Song variability : how and why ?(how to demonstrate direct contribution of AFP to adult birdsong?)

2

(Kao et al, 2005)

AFP Pathway

3

(Kao et al, 2005)

Motor Pathway

Basal ganglia-forebrain circuit(anterior forebrain pathway)

What we know• AFP activity correlated with singing

• LMAN lesion → no change in ongoing song

• HVC+RA (motor pathway) stimulation → vocalizations

• LMAN stimulation → no vocalization elicited and no gross change on song

=> LMAN not required structure for song production

=> What is its purpose then ? Hypothesis :AFP activity modulates vocal control via LMAN activity patterns ?

4

(Kao et al, 2005)

Methodology: manipulating LMAN activity

5

(Kao et al, 2005)

Microstimulation of LMAN during precisely targeted parts of a song using real-time template-matching algorithm

Results: pitch+loudness modulated by LMAN

6

(Kao et al, 2005)

(sd ; P < 0.0001) (sem ; P < 0.0001)

Frequency shift Amplitude shift

Using fixed current stimulation

Results: LMAN is functionally compartmentalized

7

(Kao et al, 2005)

And high current produce song suspension, like HVC stimulation !

Methodology: social behavioral analysis

8

(Kao et al, 2005)

Spectrogram + neural activity recordings when presented with a female

Undirected singing Directed singing

Methodology: social behavioral analysis

9

(Kao et al, 2005)

Spectrogram + neural activity recordings when presented with a female

Undirected singing Directed singing

Methodology: social behavioral analysis

10

(Kao et al, 2005)

Spectrogram + neural activity recordings when presented with a female

Undirected singing Directed singing

After <= 2 min, hide female + play undirected songs

Results: Context modulates LMAN activity

11

(Kao et al, 2005)

Pitch mean is not changed (needs confirmation...), only variability !

(meanP = 0.54)(varianceP < 0.0001)

Correlation of LMAN activity and song variability

12

(Kao et al, 2005)

=> LMAN necessary for context-dependent variability (confirmed by stereotaxic lesion)

(R² = 0.83 ; P < 0.05) (s.e.m. ; pre-P < 0.0001 ; post-P = 0.167)

Discussion• What pathway(s) for context modulation ? (what modulates

LMAN difference in activity between directed and undirected singing? Dopamine ?)

• Exploration-exploitation dilemma : what is the exploration probability ? And how is this value chosen ? Is it dynamic ?

• How are those new explored syllabes evaluated ?

• Cerebellar implication ? (to bias variability towards the correct pitch in juvenile learning ?)

• Different sample sizes for the two conditions (class skewing)

• Need extended theory about amplitude modulation (here the article is mainly studying frequency!) 13

Take home message• LMAN induces acute changes in individual song

elements (syllabes) frequency (pitch) and amplitude (loudness), without altering order nor structure of subsequent syllabes

• Noise and variability can be used advantageously to explore new unknown solutions, but can become pathological (Parkison?)

• Exploration behavior promoted in undirected singing (« training mode »), while exploitation in directed

• Natural organisms exhibit a solution to the exploration-exploitation dilemma close to the epsilon (noise) trick→ possible predictive model ? 14

– Contributions of an avian basal ganglia–forebrain circuit to real-time modulation of song, Kao, Mimi H., Allison J. Doupe, and Michael S. Brainard, 2005 Nature 433.7026 (2005): 638-643.

– Behavioral and Neural Signatures of Readiness to Initiate a Learned Motor Sequence, Rajan R. & Doupe A., 2013, Current Biology, 23 (1) 87-93.

– Interruption of a basal ganglia–forebrain circuit prevents plasticity of learned vocalizations, Brainard, M. S., & Doupe, A. J., 2000, Nature, 404(6779), 762-766.

– Social context modulates singing-related neural activity in the songbird forebrain, Hessler, N. A., & Doupe, A. J.,1999, Nature neuroscience, 2(3), 209-211.

References slideshare.net/LRQ3000

Thank you! slideshare.net/LRQ3000

Bonus Slides

THE END