Nervous Pathway Eliciting Reproductive Behaviour - Anatomy & Physiology

Sensitization

• Reproductive behaviour can only take place if the neurons in the hypothalamus have been sensitized to respond to sensory signals.

Male

• Testosterone is aromatized to oestradiol in the brain. Oestradiol promotes reproductive behaviour.
• Testosterone is produced in small episodes every 4-6 hours.
• Relatively constant supply of testosterone, thus oestradiol, to the hypothalamus in the male.
• This allows the male to initiate reproductive behaviour at any time.

Female

• Only experiences high oestradiol during the follicular phase.
• Will only display sexual receptivity during oestrus.

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Generic Neural Pathway for Sexual Behaviour

• Under the influence of oestrogen, sensory inputs such as olfaction, audition, vision and tactility send neural messages to the hypothalamus .
• Sensory afferent neurons synapse directly on neurons in the ventromedial and pre-optic hypothalamic regions.
• These sensory inputs cause neurons in the hypothalamus to release behaviour specific peptides that serve as neurotransmitters.
• Neurotransmitters act on neurons in the midbrain.
• Neurons in the midbrain serve as receiving zones for the peptides produced by hypothalamic neurons.
• Midbrain translated neuropeptide signals into a fast response.
• Neurons in the midbrain synapse with neurons in the brain stem (medulla).
• Nervous signals are integrated in the medulla.
• From the medulla, nerve tracts extend to the spinal cord where nerves synapse with motor neurons that innervate muscles that cause lordosis and mounting.