Topic 7:

More on Male Reproductive Behavior

This topic based to a large extent on Chapter 5 materials in the second half of the chapter.

5.10 Maintenance versus restoration of sexual behavior by testosterone therapy

What do you think could explain the difference in ejaculation rates?

5.13 Regions that are essential to the control of sexual performance in male rats

POA – lesions abolish male sexual behavior and regulates neuroendocrine function in the brain.

5.14 The vomeronasal organ (VNO)

The vomeronasal organ (VNO) is absent in most primates, but essential in rodent reproductive behavior…. because it is used by the male in his investigatory behavior to assess if the female is ready in the right part of her ovulatory phase.

The male’s investigation will lead to both liquid and gaesous chemicals being taken in. Typically gaseous chemicals will enter the nasal cavity and stimulate the VMO, whereas liquid chemicals that are brought into the oral cavity by the tongue will pass through the nasopalatine duct to stimulate the VMO.

5.15 The amygdala

The amygdala is the brain region that is a pair of almond-shaped groups of nuclei located deep within the medial temporal lobes of the brain. It is the site for routing of many aspects of behavior including memory & emotions in humans.

In rats, the olfactory bulbs feed into the amygdala, and hence there is a shaping of the signals by this region.

In rat studies, two amydaloid regions are identified:

Basolateral – not involved in rodent sex behavior Corticomedial – involved in rodent sex behavior

5.16 Neural pathways in the rat olfactory system

The olfactory amygdala is therefore distinct from the vomeronasal amygdala.

5.17 Castration reduces neural responsiveness in the MPOA

5.18 The distribution of sex steroid receptors

5.19 Brain regions in rodents that show fos activation after sexual stimulation

fos – one of the IEGS (intermediate early genes responsible for developing sex behavior.

5.20 Schematic depiction of neural activity in circuits underlying male sexual behavior

Difficult to learn just by talking about it, please exam in detail this figure in the text.

5.21 Extracellular dopamine in the MPOA is elevated by cues from the female

Dopamine can be supplied as a medication that acts on the sympathetic nervous system.

5.22 Copulatory sequence of rats mating in groups

5.23 LH secretion can be modified by classical conditioning

5.24 Individual differences in sex drive

5.25 Clinically low testosterone concentrations can restore mating behavior

5.29 The frequency of male sexual behavior changes with age

5.30 Plasma testosterone concentrations in human males

5.31 Individual variation in weekly frequency of sexual outlet in men

5.32 Effects of testosterone treatment on hypogonadal men (Part 1)

5.32 Effects of testosterone treatment on hypogonadal men (Part 2)

5.41 Hormones mediate pseudocopulation in parthenogenetic whiptail lizards

Box 5.1 Battles of the “Sexes”

Box 5.2(A) Anatomy of the Penis (Part 1)

Box 5.2(B) Anatomy of the Penis (Part 2)

Box 5.3(A) Erectile Dysfunction, Nitric Oxide, and Viagra (Part 1)

Box 5.3(B) Erectile Dysfunction, Nitric Oxide, and Viagra (Part 2)