Reverse Engineering of the Lordosis Behavior Neuronal Circuit

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Reverse Engineering of the Lordosis Behavior
Neuronal Circuit

• Donald W. Pfaff
• Anna Lee, Nandini Vasudevan, Lee-Ming Kow
• Laboratory of Neurobiology and Behavior
• Rockefeller University
• New York

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1. Endocrine, neural, genetic mechanisms for the
   simple sex behavior, lordosis.
2. Reverse engineering the circuit, module by module
3. Negative and positive feedback
4. Hormone actions with different time constants
5. Mechanisms for fundamental CNS arousal

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The Receptors(Pfaff, Science 1968 J. Comp.
Neurology, 1973)
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Neural circuit.
Neural circuit for lordosis behavior.From
Estrogens Brain Function.(Springer-Verlag).
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Genes.
Genes controlling lordosis behavior. From Drive.
(M.I.T. Press).
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The Behavior(Estrogens and Brain Function)

• Steroid hormones coordinate brain function with
  rest of body to ensure reproduction appropriate
  to environment.
• Mechanisms understood from receptor chemistry
  (Angstroms) through seasonality (light years).

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Conclusion

• Specific biochemical reactions in specific
  nerve cell groups of the mammalian brain
  determine a biologically crucial behavior.

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adds endocrine dependence. coordinates brain with
body
translates slow neuroendocrine to fast CNS
signaling
coordinates responses across all the spinal
segments
local business segmental stretch and flexion
reflexes in response to local stimuli
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III. Questions about feedback

• Given the cutaneous stimulus, lordosis behavior
  looks ballistic no feedback.
• The negative feedbacks in these systems are
  endocrine steroid hormones from peripheral
  glands turning off release of the neuropeptides
  that led to their synthesis.
• Time-limited positive feedbacks do exist in my
  systems voltage-dependent conductances causing
  action potentials estradiol progesterone
  causing the ovulatory surge of LH.
• CNS mechanisms for reproduction need not be
  homeostatic.

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Feed-forward, pre-lordosis behaviors

• Fast forward, sudden stop, functions to
• F braked, prepared to support wt. of M.
• F muscularly tense facilitates lordosis.
• Leaves M in correct mounting position.
• Paces mating facilitates fertilization.

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Hormone-dependent behavioral funnel
M
F

• IFF
• Testosterone
• Flank gland,
• Scent marks

O L F A C T I O N
IFF Estradiol Scent marks
(long time, wide space)
U L T R A S O U N D
up the pheromone gradient
M
F
(limited t,s)
CUTANEOUS STIMULI
M
F
(lordosis)
(TIME)
( S P A C E )
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IV. Hormone actions with different time constants

• In a complex non-linear system with
  feedbacks, do mechanisms with different time
  constants offer any advantages? Do they
  encourage stable performance?

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hER? (from Dr. P. Chambon)
Experimental Design
bgal (pSV-?galactosidase)
48 hours
3xERE-Luc (three-tandem ERE linked to
luciferase, from Dr. D. McDonnell)
SK-N-BE2C (Human neuroblastoma cells)
24 hours
Pulse 1
Pulse 2
2-pulse paradigm
4 hrs
2h
2h

24 hrs
Luc ?gal enzyme assays, results expressed as
Luc/bgal to control for transfection efficiency.
Cell lysis
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Rapid and slow/genomic hormone actions foster
lordosis behavior.
Agonist
Transmitter receptor
Ion chnl
E2
Excitation
mER
Genomic actions of estrogen
PKC
(PKA)
(PKA)
Rapid membrane actions


PKA PKC
(In parallel)
In VMN
Neuroblastoma cells MCF-7 cells VMN neurons
Lordosis
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For the future, get data relevant to equations of
this sort

• d(t) F t, t2, dERn, g(t2, t1, dERm)

Where dERm is the change in output at time t1
that is a consequence of estrogen action at the
membrane in the first pulse. The effect of this
change on the system at the later time t2 is
given by some function g which depends on the
signal dERm and evolves between the times t1 and
t2. It may be interpreted as the change in the
basal state at time t2 in response to the signal
at time t1. The second pulse, given by dERn, is
the change due to the estrogen action in the cell
nucleus. The final response of the system is thus
given by the function F, which depends on the
times involved, the second pulse dERn and on g.
Equations conceived and written in collaboration
with Professor Parameswaran Nair, Department of
Physics, CCNY.
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V. Mechanisms for fundamental CNS arousal

• The structure of CNS arousal mechanisms is
  amenable to investigation.
• We are working toward a formal, quantitative
  description of these mechanisms.

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Literature Review
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EMOTIONAL FUNCTION
COGNITIVE FUNCTION
DECISION MAKING
FEELINGS (minutes)
SUSTAINED ATTENTION
MOODS(hours)
ATTENTION
TEMPERAMENT(lifetime)
ALERTNESS
AROUSAL
AROUSAL
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Fundamental Arousal of Brain and Behavior
Applications

• Mood Disorders (Depression, Bipolar
  Disorders)
• Vigilance/Military
• Vigilance/Shift Work
• Vigilance/Dangerous Occupations
• Toxicology (e.g., Lead in water)
• Fatigue states (CFIDS, FMS, Gulf War)

• Stupor, vegetative, coma
• Aging
• Alzheimers
• ADHD
• Autism
• Anesthesia
• Sleep Disorders

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High throughput assay of all three components
of CNS arousal
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Descending Arousal-controlling Systems
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dA Fg(Ag) F1(As1 ) F2(As2 )... Fn (Asn)
Where A is the state of arousal of the CNS at any
moment. Ag generalized arousal. Asn, a specific
form of arousal.
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Idea Information theory maths shed light on CNS
arousal mechanisms

• Arousal-related neurons respond best to
  high-information (salient, surprising,
  unpredictable) stimuli (Harvard U. Press, 2005)
• Claude Shannon devised an intuitively pleasing,
  mathematically precise definition of information
  as follows

Where H is the total amount of Shannon
information and p(x) is the probability of event
x.
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Arousal / Information theorythinking naturally
yields a universal phenomenon HABITUATION.
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