Mating-dependent plasticity in the female accessory olfactory bulb

Ian Davison, Dept of Biology, Boston University KITP Olfaction meeting, July / 2015 The accessory olfactory system

accessory olfactory main OB OB epithelium

vomeronasal organ

- vomeronasal system: detects primarily non-volatile, high molecular weight chemical cues The accessory olfactory system

- each individual has a unique set of secreted chemosignals

Hurst et al. (2001)

- forms a sensory 'fingerprint' identifying a specific individual The accessory olfactory system

Hurst et al. (2001)

- drives a pattern of neural activity in the AOB unique to that individual. The accessory olfactory system

Social behaviors: reproducon, parenng, aggression Rapid sensory imprinting: the Bruce effect

mating + imprinting

unfamiliar male

pregnancy blocked

- the 'Bruce Effect': male-induced pregnancy block in mice Rapid sensory imprinting: the Bruce effect

mating + imprinting

unfamiliar male stud male

pregnancy implantation; blocked pregnancy

- the 'Bruce Effect': male-induced pregnancy block in mice Rapid sensory imprinting: the Bruce effect

mating + imprinting

unfamiliar male stud male

pregnancy implantation; blocked pregnancy # of births#of

- the 'Bruce Effect': male-induced pregnancy block in mice Rapid sensory imprinting: the Bruce effect

mating + imprinting

unfamiliar male stud male

pregnancy implantation; blocked pregnancy

- the 'Bruce Effect': male-induced pregnancy block in mice Rapid sensory imprinting: the Bruce effect neural acvity paern imprinng: mang & cell-specific encoding specific sensory exposure suppression individual (stud) of output Inhibitory circuits in accessory olfactory bulb

mitral cells

c granule c c c cells c c c cc c c c c c c

neocortex: ≈ 1:5 olfactory bulb: ≈ 10:1

apologies to Mizrahi Inhibitory circuits in accessory olfactory bulb

- common inhibitory motifs for shaping neural output:

lateral inhibition normalization decorrelation

after Yuste Inhibitory circuits in accessory olfactory bulb

excitatory & inhibitory neurons communicate through specialized, unusual dendric synapses 500ms A 500ms A p p 80 Inhibitory circuits in accessory olfactory bulb 140

-62mV -67mV V 20mV m 100ms

Iinj

- acon potenal trains drive modest self-inhibion AOB mitral cells 20s 20s A A p p 70 140

20mV -63mV -65mV 2s Inhibitory circuits in accessory olfactory bulb

2 mV 150ms

- rapid acon potenal trains drive only modest self-inhibion in AOB mitral cells Inhibitory circuits in accessory olfactory bulb

Luo & Katz, 2003

- during natural sensory behaviors, AOB mitral cells are active for long periods – TENS of SECONDS MC self-inhibition emerges slowly

- long-lasng acvity recruits strong self-inhibion in AOB mitral cells MC self-inhibition emerges slowly

- long-lasng acvity recruits strong self-inhibion in AOB mitral cells MC self-inhibition emerges slowly

t1 t2

t1 20 mV 2s

4 mV 60 20ms

40 t2 20

FiringHzrate, 0 10 20 30 Time, seconds

- mitral cells in MAIN olfactory bulb show minimal self-inhibion a. MC self-inhibition regulates output Drug cocktail

10µM gabazine 5µM NBQX 25µM APV

-59 mV 0mV 2 10s 5mV 500ms

- pharmacology confirms that AOB output is strongly regulated by inhibion Inhibitory circuits in accessory olfactory bulb

(1) Individual AOB projection neurons can recruit extremely strongly feedback inhibition

(2) Inhibition can strongly regulate AOB output; degree of suppression varies c c c c (3) Inhibition emerges relatively slowly over time Inhibitory circuits in AOB

cell 1 cell 2 cell 3

18 18 26

9 9 13

FiringHzrate,

FiringHzrate,

FiringHzrate, 0 0 0 0 10 20 30 0 10 20 30 0 10 20 30 Time, sec Time, sec Time, sec

- different mitral cells show widely varying levels of inhibitory suppression Measuring synaptic changes after imprinting

- do mating and sensory exposure drive changes in inhibitory function in the AOB?

8 weeks ~ 7 days ~ 4.5 hrs ~ 4.5 hrs

ovarectomy induce estrus via mating sacrifice, brain & estrogen progesterone & sensory slice recording implant exposure Behavioral interactions during imprinting

25 30 35 40 45 50 Time, minutes - behavioral interactions are intermittent and repetitive Mating enhances inhibitory input to MCs

average naive exposed mated

- frequency of miniature inhibitory postsynaptic currents is increased after imprinting Mating enhances excitatory input to GCs

- both amplitude and frequency of spontaneous EPSPs are increased aer mang Mating enhances interneuron excitability

15

10

5 df spikecount

0 0 30 60 10pA 20pA 30pA 40pA 50pA current (pA) 20 mv

200ms

- after mating, granule cells become more excitable à show increased firing for the same stimulus Mating enhances interneuron excitability

-40

-60

RMP (mV) RMP df

-80 10pA 20pA 30pA 40pA 50pA

20 naive mated mv exposed 200ms

- after mating, granule cells become more excitable à show increased firing for the same stimulus Testing the cellular specificity of plasticity

naive

-2 10 unexposed mated -3 10

-4 10 -2 10 mated naive Fractioncells (log) -5 mated -3 10 10 0 1000 2000 3000

-4 GFP intensity (AFU) 10

-5 50 µm

Fractioncells (log) 10 0 1000 2000 3000 -2 GFP intensity (AFU) 10 - mating induces robust GFP expression in AOB granule cells naive mated -3 10

-4 10

-5

Fractioncells (log) 10 0 1000 2000 3000 GFP intensity (AFU) Testing the cellular specificity of plasticity

naive

mated sensory-exposed -50 naive

-60

-70

RMP (mV) RMP

-2 mated 10 -80 naive mated -3 10 2 4 6 8

-4 GFP intensity (normalized) 10

-5 50 µm

Fractioncells (log) 10 0 1000 2000 3000 -2 GFP intensity (AFU) 10 - mating induces robust GFP expression in AOB granule cells naive mated -3 10

-4 10

-5

Fractioncells (log) 10 0 1000 2000 3000 GFP intensity (AFU) Output of mitral cells after mating

naive

-55 mV

mated

-55 mV

- inial responses to first smulus are similar for mitral cells naive and mated animals Output of mitral cells after mating

naive smulus #

1 -55 mV

2

3

.

.

.

.

.

10

- dynamics of MC output are strongly altered aer mang Output of mitral cells after mating

naive mated smulus #

1 -55 mV -55 mV

2

3

.

.

.

.

.

10

- dynamics of MC output are strongly altered aer mang Mating leads to slowly emerging suppression

1.5 6 naive mated

1.0

3

Count 0.5

Normalizedspike count

0.0 0 1 4 7 10 Stimulus number Suppression index

- aer imprinng, many MCs - populaon distribuon for show marked drops in firing reduced responsiveness for repeated smuli Mating leads to slowly emerging suppression

smulus # 1 2 3 . . . . 10

naive

mated

0

- decrease in responsiveness -5

Vm, mV Vm, is due to a progressive

∆ reducon in resng membrane potenal -10 1 4 7 10 Stimulus number Cellular specificity of learning (ii)

naive mated female female

- a subset of stud-acvated MCs are labeled with Fos-GFP aer mang - allows targeted recordings of cells encoding the learned cue Cellular specificity of learning (ii)

low 20 Fos-GFP

10 high 20 mV Fos-GFP 1 sec

FiringHzrate,

0 20 30 40 Time, sec

3 mV 100 ms

- neurons activated during prior mating experience are more strongly suppressed than cells lacking GFP expression Cellular specificity of learning (ii)

High GFP Lowlow Fos-GFP GFP

1st -60mV -60mV

10th -60mV 40mV 5s

1st

10th 5s

- stud-activated neurons become unresponsive over time Cellular specificity of learning (ii)

High GFP Lowlow Fos-GFP GFP Highhigh Fos-GFP GFP Low GFP

1st 1st -60mV -60mV -60mV -60mV

10th 40mV 10th -60mV 40mV -60mV 5s 5s

1st 1st

10th 10th 5s 5s - stud-acvated neurons become unresponsive over me Mating leads to slowly emerging suppression

smulus # 1 2 3 . . . . 10

GFP(-)

GFP(+)

- mitral cells lose responsiveness due to progressive hyperpolarizaon Cellular specificity of learning HIGH_GFP(n=8) LOW_GFP (n=8) 3000 te 11.5.5 a * * * * * r ng i r 2000 i 11.0.0 c f c ed c c c z li 1000 cc 00.5.5 cc cc cc cc cc ma Cumulative#spikes r o Normalizedspike count N 0.0 0 0 1 4 7 10 1 4 7 10 Stimulus number Stimulus number

- stud-encoding mitral - cumulave output from cells show a striking loss the AOB is strongly reduced of responsiveness AOB plasticity after mating – key points

(1) Inhibition is upregulated; changes in multiple points in the inhibitory feedback pathway

(2) Inhibitory plasticity is broadly distributed, with no obvious cellular specificity

(3) Imprinting also leads to plasticity in intrinsic excitability

(4) Mitral cell activity acquires a strong history-dependence: initial responses are similar, but responses to subsequent stimuli are markedly reduced

(5) Dynamic regulation of mitral cell responses is specific to the neurons representing the stud male. Reducing memory interference? individual 1 individual 2

slow temporal filtering may prevent learning from obscuring sensory cues from other individuals Separate timescales for hormones and behavior?

early: sensory information fully available for detection, discrimination, and rapid behavioral decisions; limits memory interference

late: lowered sensitivity reduces the impact of the imprinted pheromones on neuroendocrine status

slow temporal filtering may allow separation of behavioral and neuroendocrine effects THANKS

Yuan Gao Mike Baum Linnea Herzog Jim Cherry Carl Budlong Howard Eichenbaum Ellen Witkowski Kelsey Williford Yoram Ben-Shaul Steve Shea Will Liberti Adi Mizrahi Johnny Elguero Sean Tobyne J.P. Arrivillaga William Mau

Jake Gruber Anya Golkowski NIH/NIDCD R21DC013894 Cory Dubois