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PSYC2007_PBLvoles_raw_notes

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					                                               Voles Raw notes
               WHY                  HOW             WHAT          WHAT NOW?
               3 – 4 double spaced A4 pages, arial 12pt
               Summerize whole paper (except abstract), add single reference at the end.
               5% of grade.                         Have this done by Friday.
               + Roughly 1200 words, plus or minus a hundred.

               ---------

               + Microtus ochrogaster = monogamous prarie vole
                     - good for neurobiological investigations of pair bonding because the
                         species shows definite selectiveness toward established partners

               + Pair bonding = not only preference for previous mates, but aggressive rejection of
               other potential mates (thus pair bond is maintained)

               vehicle treated – CSF without anything, a placebo, if you like. All voles were treated
               with something – either D1-like or D2-like, or CSF

                                        - - - - - Establishing Pair Bonds - - - - - -
               + neurological basis of why they form pair bonds rather than select new mates every
               time isn’t studied much
                       - previous studies uncovered importance of dopamine transmission on the
                           nucleus accumbens mediates mating approach and avoidance behaviours
                       - found the bit of the accumbens involved in dopaminergic processing (and
                           thus partner preferences)
                       - looked at specific functions of distinct dopamine receptor subtypes and
                           their effect on pair bonding


               + Dopamine 2-like receptors has well known effect on partner preference (presence of
               dopamine-like substance = preference).

               + accumbens = heterogenous structure, with core and shell, both areas involved in
               pair bonding but the specifics of which bit does what is unknown.




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               + Male voles paired with females for six hours without mating don’t show mating
               preference
               + Dopamine 2 like drug Quinperole can induce pair bonding in the absence of mating.
               + used quinpirole to test which bit of accumbens is responsible.
                + Once drug was injected, voles known to already have partners were placed in area
               with stranger for 6 hrs and results of these interactions were recorded.
               + Injected it quinperole into accumbens core (specific location = rostral fo the corpus
               callosum genu, brain part responsible for appetitive associations)
               + Quinpirole to core was unneffective in enducing pair bonding
               + Then stuck quinpirole into accumbens caudal shell (caudal to genu), no effect (it is
               known this region does not effect appetitive things)
               + rostral shell turned out to be specific sub shell, thus all later aspects of study looked
               at it.

               + Dopamine 1-like receptors aren’t well examined re mate preference. This study
               looked at whether its introduction to the rostral shell of accumbens inhibits partner
               preference

               + Previous studies indicate that only low levels of D1-like receptor activation induces
               partner preference
               + D1-like chemical was SKF 38393
               + quinperole-induced partners were used as control for SKF 38393 tests
               + SKF 38393 blocks quinperole, and also blocks eticlopride (another D2-like)
               + Voles receiving both Quinperole and SCH23390 (D1-like) show mating preference
               THEREFORE D1-like receptors block mating preferences brought on by D2 receptors
               + D1 receptors block partner preference without impeding other forms of mating
               behaviour
               THERFORE activation of D1 and D2 receptors have opposing effects on partner-
               preference formation (D2 promotes, D1 inhibits…)

                                      - - - - - Maintaining Pair Bonds - - - - - -
               + Voles will only mate with a partner once partnership is established, even if partner
               permanently buggers off
               + Study hypothesised that as dopamine receptors in the accumbens are pivotal to pair
               bonding formation, they must also be pivotal to bonding maintainance, and must
               somehow change once the bond is established.
               + Paired male and female voles, used a group of all-male vole siblings as a control
               group, then measured D1 and D2 receptor binding levels.
               + Males exposed to females for either 24 hrs (with and without mating) or 2 wks.
               + Those exposed for short time, or without mating, did not develop change in D1orD2
               + THEREFORE increased D1-like receptors in accumbens occurs only once pair has
               been established (for more than 24hrs), and is probably integral in long-term pair
               maintainance


               + All voles in following thingy were vehical treated
               + Selective aggression = important factor in pair bonding.
               + Introduced non-bonded males to stranger females. No aggression.
               + Introduced bonded males to bonded females. No aggression.
               + Introduced bonded males to stranger females. Agression.




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               + These scenarios were not altered by blocking D2-like receptors
               + Agression in the last condition was curbed by blocking D1-like receptors.
               + Therefore increased D1-like receptors increases long-term selective aggression, and
               thus aids in maintaining pair bond.


               + Microtus Pennysylvanicus = non-monogomous prarie voles (show low levels of
               non-affiliative behaviour)
               + As vole is related, same brain regions are responsible for pair bonding behaviour
               + These voles have higher base level of D1-like receptors, thus there can’t be more
               D1-like receptors when bonding occurs, thus selective aggression does not increase
               + Meadow voles with blocked D1-like receptors showed more generally affiliative
               behaviour (treated and untreated meadow voles were paired with a female for 6 hrs),
               but still didn’t establish pair bonds.
               + THEREFORE base D1-like receptor levels are higher in antisocial meadow voles,
               but this is but one element in explaining the differences of interspecies behaviour.

                                             - - - - - Conclusions - - - - - -


               +D2 forms, D1 maintains
               + Bond formation and maintainance involve neuroplastic reorganisation of the
               accumbens
               + Accumbens shell involved in processing positive information
               + Prarie voles can’t form a second bond, because when a bond is established D1-like
               receptors are upregulated, and D1-like receptors block D2-like receptors.
               + D1-like receptors, once the bond has formed, are upregulated in both the core and
               shell of the accumbens – therefore, the core may be important in bond maintainance
               + Other studies have shown D1-like receptors are also responsible for neuroal
               plasticity and memory (help ‘em remember their mates)
               + Individual variation in D1-like receptor upregulation may explain individual
               differences in the ability to form a second paired bond
               + Dopamine / accumbens by no mean the only element of pair bonding.




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posted:4/1/2013
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