BN Unit 2 Exam: senses, brain, social influences, reptiles and birds

In which animal groups is olfaction critical for successful MSB?

Most rodents, carnivores, and ungulates

What information does olfaction give a male about a female?

Her reproductive status (pheromones, estrus signals)

What type of cues does the main olfactory bulb (OB) process?

General olfactory cues

What pathway processes pheromonal cues?

Vomeronasal organ (VNO) → accessory olfactory bulb (AOB)

What two things do VNO/AOB pheromonal cues do for MSB?

Trigger sexual arousal and facilitate copulatory behaviors

What happens to MSB when the VNO is removed?

MSB is impaired in many species

What is a bulbectomy?

Surgical removal of the olfactory bulbs

Name three features of bulbectomy as a method.

Permanent; removes both sensory and non-sensory functions of the OB; eliminates ~4% of total CNS tissue

What is the behavioral effect of bulbectomy in rodents?

Severely impaired mating behavior

What does intranasal zinc sulfate do?

Chemically destroys the olfactory neuroepithelium, making animals temporarily anosmic (reversible)

What is the third method of impairing the chemosensory system?

Anesthesia of the nasal epithelia

What did the chemosensory impairment studies conclude?

Input from olfactory sensory neurons (OSNs) and the VNO is necessary for rodent mating; the VNO is especially important for telling male from female odors

What does castration do to neural activity in the MPOA vs the olfactory bulbs?

Reduces activity in the MPOA but not in the OBs

From where does the amygdala receive projections relevant to MSB?

The olfactory bulbs

What do basolateral amygdala lesions do to MSB?

Reduce motivation but don't affect consummatory behavior (appetitive, not consummatory)

What do corticomedial amygdala lesions do to MSB?

Increase ejaculation latencies and abolish copulation in hamsters (consummatory, not appetitive)

What does dopamine do for copulation and penile erection?

Facilitates both (via presynaptic/postsynaptic activity)

What does serotonin (5-HT) generally do to copulation?

Mostly inhibits it (depending on receptor subtype; e.g., 5-HT1A activity can facilitate)

What do norepinephrine, GABA, endorphins, and oxytocin do to copulation?

NE: mostly facilitates (α1) / α2 decreases; GABA: decreases; endorphins: decrease; oxytocin: increases

What sensory input evokes dopamine release from the three dopaminergic tracts?

Sensory input from an estrous female

What does the nigrostriatal tract do in MSB?

The largest DA system; mediates initiation of movement, including muscle movements required for mounting

Where does the incertohypothalamic tract project, and what does it do in MSB?

To the MPOA; integrates sensory and hormonal signals to drive sexual performance

What evokes DA release in the MPOA, and what does castration do to it?

Female cues (not food or male rats); castration reduces female-evoked DA release

What is the mesolimbic tract, and what does it do in MSB?

The "reward pathway"; mediates the motivational/anticipatory component of sexual behavior

What happens when DA receptors in the nucleus accumbens are blocked?

Sexual motivation is reduced

In the rhesus monkey DA agonist study, what could the males sense of the females?

See, hear, and smell, but not touch them

What did a low dose of DA agonist cause in male rhesus monkeys?

Yawning

What did a moderate dose of DA agonist cause in male rhesus monkeys?

Erections, masturbation, and sometimes ejaculation

What was critical about when the DA-agonist sexual responses occurred?

Only in the presence of female cues — DA mediates female-evoked sexual responses

What is a common sexual side effect of SSRIs?

Sexual dysfunction

Explain how serotonin reduces male sexual motivation.

Serotonin released in the lateral hypothalamus inhibits DA release in the nucleus accumbens

What question did the hyposexual → hypersexual individual-differences study ask?

Are individual differences in sex drive due to circulating hormone levels?

In the individual-differences study, what happened after castration and T replacement?

Each male returned to his OWN pre-castration level of MSB, even on the high dose (high-drive stayed high, low-drive stayed low)

What do the low-T studies show about maintaining sexual behavior?

Low concentrations of circulating testosterone can maintain sexual behavior

If not T level, what may explain individual differences in MSB?

Differences in target tissues (e.g., receptors) or early environmental stressors

What is the Coolidge effect?

A male mated to satiation will immediately resume copulating if a new female is introduced

In which species is the Coolidge effect seen and not seen?

Seen in rats and cattle; not seen in monogamous species such as prairie voles

What does the Coolidge effect show?

Enhanced mating performance and motivation with novel females

What is the "vaginal code"?

The intervals and pacing of intromissions during copulation, critical for reproductive efficiency

In a large, semi-natural arena, who controls intromission pacing, and why does it matter?

The female; she can set the rate for optimal sperm transport and fertilization

In a small test cage, who controls pacing, and what is the result?

The male; faster intromission rates, which may reduce reproductive efficiency vs female-paced mating

What kinds of social subgroups exist in group-mating rats?

Pairs, harems with or without offspring, unisexual groups, single males and females; "promiscuous mating"

According to sperm competition studies, which male is most likely to sire offspring?

The male with the most ejaculations, or the last one to ejaculate

Describe the Pavlovian conditioning study of MSB in rats.

Rats were exposed to wintergreen odor, then conditioned with wintergreen–estrous female pairings; later wintergreen alone raised LH and testosterone to levels like an unconditioned rat exposed to a female

What is conditioned place preference (CPP)?

A learned preference for a place previously paired with rewarding events

How do male mice show CPP related to sex?

They prefer a chamber where they experienced mating

Do most snakes keep mating after castration?

No — most stop mating

Which snake is the exception that keeps mating after castration?

The red-sided garter snake

Which sex is larger in red-sided garter snakes?

Females

When do male red-sided garter snakes emerge from hibernation relative to females?

A few weeks earlier, in early spring

What is a "mating ball"?

Many males trying to mate with each female as she emerges

What do other male garter snakes do once one achieves intromission?

They stop courting that female

What is an associated reproductive pattern?

Reproductive behavior, gonad enlargement, high steroid hormones, and gamete production all occur at the same time

What is a dissociated reproductive pattern?

Reproductive behavior occurs even when steroid levels are low and gamete production is minimal

Which reproductive pattern do red-sided garter snakes show?

Dissociated

Which manipulations have NO effect on garter snake mating?

Castration, removing the pituitary, removing the adrenals, androgen treatment, gonadotropin treatment

Which manipulations DO affect garter snake mating?

Destroying the MPOA and removing the pineal gland

Besides snakes, what other group shows mating partly separate from hormonal control?

Primates

Give examples of bird courtship behavior.

Food delivery, dancing/displays, preening

Which phases of bird sexual behavior depend on androgens?

Both appetitive and consummatory

What happens to courtship and mating in castrated birds (like Berthold's roosters), and with androgen replacement?

Castration eliminates them; androgen replacement restores them

What does DHT specifically restore in birds?

Precopulatory (appetitive) displays

What are the four components of Japanese quail sexual behavior?

1. Strutting 2. Crowing 3. Mounting 4. Cloacal contact

What happens to the four quail behaviors after castration?

All four are lost

Which quail behaviors does castration + DHT restore?

Strutting and crowing (appetitive), but NOT mounting or cloacal contact

Which quail behaviors does castration + testosterone restore?

All four

What happens if aromatase or ERs are blocked when T is given to castrated quail?

T can't restore copulatory behaviors

What does the quail aromatase/ER evidence suggest?

Estrogen made locally in the brain (POA) by aromatizing T activates copulatory behavior

Where in the quail brain are estrogen receptors and aromatase found?

The preoptic area

What is the golden-collared manakin courtship display?

Males clear a court on the forest floor and perform rapid acrobatic jumps between saplings with loud wing snaps

How does manakin testosterone track courtship across the year?

T is high during the courtship season (early in the year) and drops as courtship ends and rains start

What allows manakins to make such high-speed display movements?

High expression of androgen receptors in the wing muscles and spinal cord

What happens when displaying male manakins get an anti-androgen?

Reduced courtship displays

What happens when juvenile male or female manakins get testosterone?

They perform courtship displays (and express ARs on wing muscles)