1. DO SONGBIRDS
ALWAYS HAVE A
SONG STUCK IN
THEIR HEADS?
PRESENTATION BY JENNIFER CUMMINGS
WORK DONE IN THE LAB OF DR. JOHN KIRN

2. THE ZEBRA FINCH
• Very specific
song structure
• Learn to sing
from a male tutor
Let's hear one!

3. HUMANS AND SONGBIRDS
BOTH POSSESS CRITICAL
PERIODS
Critical Period: A span of time during which exposure
to certain stimuli is necessary in order for organism to
develop a skill.
In Zebra Finches, most song learning is completed by
90-120 days post-hatch.
From Brainard & Doupe, 2002, Nature, 417:351

4. HVC projects both
directly and indirectly
to RA (robust
nucleus of the
arcopallium), a
region that projects
onto areas in the
brain stem
innervating
respiratory and vocal
motor neurons.
THE HIGH VOCAL CENTER
(HVC) PLAYS A KEY ROLE IN
LEARNING AND MAINTENANCE
From Reiner et al, 2008

5. A DECREASE IN NEUROGENESIS IN
HVC IS ASSOCIATED WITH THE
CLOSURE OF CRITICAL PERIOD
Neurogenesis: The formation of new neurons.
Neurogenesis in HVC is high throughout critical period, but
decreases when song is crystalized.
From Pytte et al., 2009

6. INTERNEURONS??
• Parvalbumin: A calcium-binding protein expressed in fast-
spiking inhibitory interneurons
• The maturation of PV+ interneurons in other systems is
associated with critical period plasticity.
• Implanting them can reopen ocular dominance plasticity
after the critical period!
• But what about the birds?

7. METHODS
• Inject with BrdU to birthdate markers at different timepoints
• Perfuse, use immunohistochemistry and confocal microscopy
• Computer-driven similarity scores between tutor and tutee

9. 0
5
10
15
20
25
20 40 60 120
BrdU/PV+NeuronsperThousandHVCNeurons
Age at Time of BrdU Injection
Rates of Parvalbumin-Positive Neuron
Addition as a Function of Age
5
3
3
4
Rates of PV+ neuron addition reflect neurogenesis to HVC generally

10. PV+ NEURON ADDITION AT 60 DPH
CORRELATES WITH SONG COPYING
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 10 20 30 40 50 60 70 80 90 100
NumberofBrdU/PV+CellsperThousandHVCNeurons
Percent Similarity of Bird's Song Vs. Tutor's Song
Song Similarity Scores Vs. Parvalbumin- Positive Neuron
Addition at 60 dph

11. 0
2
4
6
8
10
12
14
16
18
20
60 60 ISO 120 120 ISO
NumberofPV+/BrdU+NeuronsperThousandHVCNeurons
Age at Time of BrdU Injection and Housing Condition
Rates of Parvalbumin-Positive Neuron
Addition as a Function of Age
5
5
3
3
Isolates have more PV+ neuron addition than normals

12. 0
100
200
300
400
500
600
700
60 60 ISO 120 120 ISO
PV+NeuronsperThousandHVCNeurons
Age at Time of BrdU Injection and Housing Condition
Total Number of Parvalbumin-Postive
Cells in HVC as a Function of Age and
Housing Condition
5
3
3
5
By 180 days post-hatch, isolates have way more PV+ neurons in HVC

13. PV Expression
Normally-Reared Vs. Isolates

14. CONCLUSIONS
• Parvalbumin-expressing interneuron addition occurs at
rates similar to overall neuron addition during the critical
period
• Addition is highest at 40 dph, when bird begins to actively
sing, so they may mediate between template and BOS
• Higher rates of addition in isolates may allow prolonged
circuit plasticity
• But what about the original
question?

15. THANK YOU SO MUCH
• Dr. John Kirn
• Kemal, Maddy, Shannon + all past members of the lab
• The McNair Foundation
• Ronnie Hendrix and Suzanne O’Connell
• The cohort