Lecture 6 Flashcards
What is behavioral neuroscience?
Exploration of the brain pathways that lead to different behaviors.
What does behavioral neuroscience include?
- Objective descriptions of behavior.
- The study of the anatomy of brain pathways.
- The study of the neurochemicals that are used in these pathways (including hormones).
- How these pathways develop (including genetics).
What behaviors are studied in behavioral neuroscience?
-Some active areas of research include…
- Feeding
- Sex
- Aggression
- Day/night rhythms
- Sleep
Men and Hormones
- Hormones play a permissive role in humans.
- Boys who produce little testosterone at puberty have little interest in sex unless given testosterone.
- Men with testicular cancer (and testicular removal) show little interest in sex unless given testosterone.
- However, very little testosterone is needed.
- Increasing testosterone does not increase sex drive, as in rats.
Women and Hormones.
- Women, after menopause, sometime exhibit decreased sex drive and pain during sex.
- Administration of low levels of estrogen and testosterone can restore drive and genital experience.
SRY (Sex Determining Region on the Y-Chromosome)
- It will produce a hormone that we call Testes Determining Factor, or TDF.
- So, the SRY gene has the code to make TDF, and that acts as a hormone.
- It goes in the blood and acts on the body.
Erection, ejaculation, etc. are all reflexive, which means what?
We don’t need our brain to do that.
Sensory pathways from the genitalias do what?
- They bring in touch information from the penis and the clitoris, and really, from everywhere around the genitalias.
- That information then goes into the lumbar section and the sacral section of the spinal cord.
- So, the axons will form a synapse with a neuron in the spinal cord, and a branch will go into the brain.
- The branches that go into the brain are responsible for bringing that sensation into the CNS, which will result in perception at the level of primary somatosensory cortex.
In both sexes there is a synapse in the spinal cord that will activate in both cases neurons of the ________?
- Parasympathetic and sympathetic nervous system.
- In sexual behavior the parasympathetic and sympathetic nervous system both have to work together.
- The parasympathetic pathway will result in genital engorgement. (Increase blood flow to the genitalia).
- The sympathetic pathway will result in the release of lubricating fluids in both sexes.
A third pathway that goes to the ________ of the genitalias, which cause ________.
- Muscles.
- Contraction during orgasm.
- The third pathway is excited by the sensory information coming in.
Why is it when we go about our day and our clothes rub up against us, we don’t immediately have an orgasm?
- One component is the neurons need to be excited enough in order for these reflexes to happen.
- Another component is there is a “break” in the system that inhibits excitation.
- Testosterone and estrogen can hinder the break, as well as certain sights, sounds, and feelings.
What part of the brain is sexually dimorphic?
- The hypothalamus.
- The SDN (Sexually Dimorphic Nucleus) is larger in males than females.
- There is also a difference in this part of the brain based on sexual orientation.
It is not just the structure of the brain that is different between sexual orientation, but we also see….
….different function in the brain.
What is AND?
- AND is androstenedione, which is a chemical we find in male sweat.
- It’s derived from testosterone.
- It is a weird chemical because most people cannot detect the actual odor of it, but whether a person can detect the odor or not, it does slightly change people’s physiology.
- For example, when women smell this, their heart rate slightly goes up, and they sweat a tiny bit more as if the sympathetic nervous system has been activated.
- It turns out you can detect activity in the hypothalamus when you let people smell this odor.
- Heterosexual women have activity in the hypothalamus when they smell this, as do homosexual men. However, heterosexual men do not.
Oxytocin
- Involved in pair bonding in female voles.
- Infusion of oxytocin into the brain produces pair bonding.
- Mimics the natural production of oxytocin from sexual behavior.
