Social bonding Flashcards
Olfaction pathways in social bonding
Non-volatile olfactory cues e.g. pheromones processed by VNO which projects to AOB.
Bind to V1R & V2R (GPCRs) which initiate intracellular signalling cascade which opens TRP2 cation channels in membrane = depolarisation.
Projections to amygdala to activate reward pathways & elicit social bonds.
K/O studies (e.g. Keverne 2002, Haga 2010, Ferrero 2013) show this system is crucial for ID & social bonds.
Keverne 2002
K/O TRP2 = males try to mount other males instead of being aggressive towards them, females no longer aggressive to male intruders.
Haga 2010
Female rats can detect pheromone ESP1 in male tear fluid which primes her to be sexually receptive (show lordosis).
Ferrero 2013
Adult male rats can detect pheromone in juvenile females so don’t try to mate with them.
K/O TRP2 = try to mate with juvenile rats.
Prairie vole
Highly affiliative, biparental, male aggression to other males, monogamous.
Prefer partner in PPT.
Female prairie & OT
Vagino-cervical reflex arc during mating releases OT which feeds back to brain & activates OT circuits.
Inject OT without mating = bond, prefer partner in PPT.
OT antagonist = no bond.
No effect of OT in male prairies, or montane!
Male prairie & AVP
Inject AVP without mating = bond. AVP antagonist blocks this.
Increases affiliative and paternal behaviour.
No effect in female prairies, or montanes!
Young 1999
Differential distribution of V1ARs in male prairie: high in LS, VP (mesolimbic dopaminergic reward areas)
Young 2006
MRI shows differential distribution of OXTRs in female prairie: high conc in BST & NAc (mesolimbic dopaminergic reward areas)
Density correlates with strength of pair bond
Selective injection of OXTR antagonist (Young & Wang 2004)
Inject into NAc or PFC of female prairies = blocks partner preference.
No effect if injected to CP.
So only works in certain sites due to differential receptir distribution.
D2R/OXTR antagonists in female prairies (Young & Wang 2004)
D2 (but not D1) antagonist injected into NAc abolished partner preference in female prairies.
Injection of D2 agonist restored this, but could be blocked by OXTR antagonist.
Shows both DA & OXT receptor signalling is crucial for pair bond formation in female prairies.
Donaldson & Young 1998
AAV transfer of expanded microsatellite region of V1AR prairie gene into montane vole = increased expression of AVPRs in reward areas of brain so montane forms pair bonds & becomes monogamous.
Young 1999
Transgenic mice with expanded prairie vole gene = monogamous.
Landgraf 2003
K/O V1AR gene = impaired social recognition. Continue investigating known rats etc.
Rescued by AAV injection of receptor to LS = can now recognise individuals long-term.
Bartels & Zeki 2004
fMRI: images of love activate areas of human brain implicated in OT & AVP signalling.