Lecture 8 (Bechtold)

Question 1

what does bonding require?

Answer 1

olfaction, social recognition and social memory

varies by species

Question 2

social recognition mouse models

Answer 2

Strange males are attacked and commonly killed by resident male

Resident males rapidly attempt mating with strange females

Question 3

Roles, projections and responses of mouse main olfactory system?

Answer 3

Detects volatile compounds

Pathways project from olfactory bulb to Amygdala (OSNs of olfactory epithelium –> MOB)

Responds to wide range of social and non-social cues

Question 4

Roles, projections and responses of mouse accessory olfactory system?

Answer 4

Vomeronasal organ (VNO)

Detects non-volatile compounds

Pathways project to Amygdala (via AOB)

Detects socially relevant non-volatile cues

VNO is a sexually dimorphic structure, ie rat and mice male>female due to testosterone.

Question 5

What is a pheromone?

Karlson and Luscher

Answer 5

“Substances secreted to the outside of an individual and received by a second individual of the same species in which they release a specific reaction, for example, a definite behaviour or developmental process”

Substances secreted by one individual which elicit specific behaviour in another of the same species

Question 6

Where is the VMO located?

Answer 6

roof of mouth, behind main olfactory bulb.

Question 7

VMO lesion leads to?

Answer 7

abolition of Male/Maternal aggression towards intruder male (strongly dependent on a functional VNO)

also reduces sexual behaviours, mounting.

Question 8

VNO pathways?

Answer 8

different structures and outputs, but eventually both converge downstream on amygdala.

anterior/posterior AOB

Question 9

VNO receptors?

Answer 9

Vomeronasal sensory neurons (VSN), GPCR
V1R and V2R

Detect pheromones - very sensitive mammalian chemoreceptors.

V1R very specific
V2R more general

V1R - anterior AOB
2R - posterior AOB
both converge downstream at amygdala

Complex with MHC class 1b and B2-microglobulin

Question 10

what is a releaser pheromone?

Answer 10

Many examples of single or few molecules which elicit dramatic and immediate behavioural effects

Question 11

What is a primer pheromone?

Answer 11

Chemical signal which cause longer term effects on neuroendocrine or developmental pathways

Question 12

examples of rabbit pheromones?

Answer 12

nipple searching pheromone in rabbits, as babies blind.

Question 13

boar releaser pheromones?

Answer 13

2 testosterone derived molecules, spray on back of sow to check whether she is on eostrus

Question 14

VNO GPCR second messenger signalling

Answer 14

Transient receptor potential (TRP) superfamily, ion channels. TRPC2 ion channel particularly.

(not cyclic nucleotides like most)

Question 15

TRP2 knockout mice

Answer 15

can’t detect males over females.

male aggression eliminated, also sexual behaviour towards male increases.

Question 16

V1Rab knockout mice

Answer 16

maternal protective behaviour attenuated (latency to attack, time attacking, number of attacks), but not pup directed behaviours (retrieval).

sexual behaviour attenuated but not male male aggression.

Question 17

ESP-1

from where by who

F- effect and M/F brain response differences

TRCP2

Answer 17

secreted by male mice in tears, detected by females.

increase in sexual behaviour for females when detected.
requires TRPC2.

both male and female amygdala responded, MPA high male response, VMH strong female response.
VMH goes on to produce sexual behaviour response.

ESP1 is not effective in female TRPC2 deficient mice

Question 18

ESP22

from where by who

Answer 18

pheromone produced by females in tear fluid.

produced up to ~ 5 weeks old- cue to indicate sexual immaturity.

if put onto females, male sexual behaviour towards the female is reduced.

TRP2 knockout don’t show response.

Male mice do not exhibit sexual behaviour to juvenile females (but Trp2-/- do!)

Question 19

sweaty t shirt study

Answer 19

(men wore t shirt for two days)

women were most attracted to men with an MHC most dissimilar from their own.

reports were reversed when women were taking oral contraceptives.

smells reminding the women of their own/former mates were more likely to be MHC dissimilar than MHC similar.

Question 20

Evolution of the neural framework for social bonding

Answer 20

most forms of bonding are likely built upon the neural framework evolved for infant-mother bonding (similar pathways w/o E input)

Question 21

oxytocin and vasopressin functions

Answer 21

They act as hormones – secreted from posterior pituitary.
Oxytocin: Labour, uterine contractions, and milk let down

Vasopressin: Water balance

They act as neurotransmitters within the brain.
Oxytocin: Mate and offspring recognition, feeding

Vasopressin: circadian system, sex drive, learning memory

Question 22

oxytocin pathways?

Answer 22

post pituitary to PVN and SCN

Question 23

oxytocin knockout

Answer 23

social recognition impaired in both sexes.

main olfactory system not impaired

normally male mice get bored of same female if put repeatedly into cage, KO treat her as if new everyday.
can’t recognise her. vice versa.

if test non social olfactory cues, ie scent, they show same acclimitisation to stimuant and get bored.

Question 24

role of amygdala?

Answer 24

involved in enforcive or affiliative behaviours.

modified by oxytocin

Question 25

VNO projects where?

Answer 25

AOB accessory olfactory bulb, projects to amygdala

Question 26

PVN projects where?

Answer 26

amygdala via oxytocin.

Question 27

amygdala and testosterone/oestrogen?

Answer 27

check out some paper Sano et al 2016

Question 28

sex steroids priming oxytocin signal?

Answer 28

oestrogen increases oxytocin production, also production of receptors in amygdala.

Question 29

oestrogen receptor KO mice?

Answer 29

social defects similar to OT KO

Question 30

VNO structure?

Answer 30

sexually dimorphic.
Hormonal cascade from GnRH neurones initiates perinatal testosterone surge in males which masculinises the pathway

Allows sex specific response to pheromones
(male pheromones elicit gene activation in these structures in female mice).

Question 31

Evolution of AVP and OT

Answer 31

AVP like found in cyclotosomes… precursor in invertebrates…. ancient