week 11 Flashcards
What did the yale scientists discover?
brain region that controls hunting, and have found a way to switch it on and off
two sets of neurons in the mouse brain underpin the instinct to kill
What are the two sets of neurons in the mouse brain?
- One coordinates the pursuit to prey
- While the other controls the neck and jaw mucles used for biting
- Both are in the amygdala
What is the consequence of modifying these neurons?
They could be activated by laser light
A technique called optogenetics
Able to switch these circuits on whenever they wanted
What happened when the laser was off?
The mice padded around their cages normally
What was the consequence of the laser being on?
The mice suddenly launched frenzied attacks on almost anything in their paths
After jumping on the “prey”, the mice grabbed it with their paws and repeatedly sunk in teeth
Why was optogenetics used?
to create new receptors that open up to ions in the presence of blue light
What is monogamous pairing?
General relationship between an adult male and an adult female for the purpose of sexual reproduction
What was a strong interest from scientists, psychologists and neuroscientists in 1950?
Identify the neurobiological circuitry of behaviour
What does microtine rodent provide?
Unique model to study the neurobiology underlying pair bonding and selective attachments that form between adults
What has been linked to individual and species differences in monogamy-related behaviours?
Diversity in vasopressin 1a receptor (V1aR) distribution
such as:
- partner preference
- mate guarding
- space use
What does the monogamous prairie voles (Microtus ochrogaster) provide?
Laboratory-amenable species for studying the neural and molecular basis of selective social attachment between adults
What can be manipulated in a laboratory setting similar to mice and rats?
Voles
What is a partner preference test?
- The partner vole and a novel, opposite-sex individual are tethered at opposite ends of a three-chambered apparatus
- The test vole can freely explore the apparatus for 3 h, and the amount of time interacting with each tethered individual is recorded
- Pair-bonded voles will spend the majority of their time huddled with their partner while an unbonded vole will not show a preference for either individual
What is required for partner preference and other components behaviours of monogamy?
signaling initiated by oxytocin, dopamine, endogenous opioids, and AVP
How does the species-specific characteristic of these neuromodulatory system identified?
researchers compared prairie voles with the closely related but nonmonogamous meadow voles (Microtus pennsylvanicus) or montane voles (Microtus montanus)
What is the mating system of the prairie vole and montane vole?
- Prairie vole - Monogamous
2. Montane vole - Promiscuous
What is the parental care for prairie vole and montane vole?
- Prairie - Biparental
2. Montane - Maternal
What is the partner preference?
- Prairie - High
2. Montane - low
What is the selective aggression and social contact for prairie vole ?
- High
What were biologists looking at?
Differences in habitats
Contribute to differences in the evolution of the behaviours
What does a prairie vole display?
A monogamous mating system
What are the differences between these 2 voles?
Social and mating behaviour of these animals
What is social behaviour correlate with?
Individual differences in V1aR patterning
What happened in the brain regions implicated in social monogamy?
- ventral pallidum
- lateral septum
There was little variation in V1aR densities betwen individuals
What happened in brain regions implicated in spatial memory?
- Retrosplenial cortex
2. resident males had nearly sixfold more V1aR expression
In the ventral pallidum (VP) what has a much lower density of V1aR binding sites than does the monogamous prairie vole?
The monongmaous montane vole
What facilitates partner preference formation in the absence of mating?
Increasing V1aR density in the VP of male prairie voles using this V1aR- expressing virus
what should facilitate the development of partner preferences in this species?
experimentally increasing V1aR levels in the VP of promiscuous meadow voles
test
What is the individual variability in V1aR expression level associated with?
Individual variation in a polymorphic microsatellite in the 5’ regulatory region of the prairie vole v1ar gene
What does individual variation in V1aR expression contributes to?
individual variation in vasopressin‐dependent behaviors.
What does analysis reveal?
V1aR levels, in some but not all brain regions, are associated with microsatellite length and that V1aR levels in those and other brain regions correlate with anxiety‐related and social behaviors
What did they suggest about the 2 species?
have similar genetic structures with exons and introns distributed similarly
What does regulators of gene expression tell?
when, where and how long a particular case in this case the AVPR1a gene is expressed
What does increased rate of transcription for the mountain voles produce?
Increased levels of AVPR1a transcript which will then increase lvels of V1aR protein in ventral pallidums
What did early neurochemical studies using voles have illustrate?
he presence of OT receptors (OTR) in many brain areas important for social behaviors
What does sensory stimulation (smell) uncrease?
Arginin vaspopressin protein expression (males) in ventral pallidum (same as reward system)
What does mating increase?
Dopamine concentration within nucleus accumbens
What leads to the development of the attachment association in males?
Simultaneous activation (coincidence detection) of AVP/OT and DA receptors in NAcc and ventral pallidum
In adult female prairie voles, what does the pharmacological activation of OTR faciliate?
- partner preference
2. in the nucleus accumbens (NAcc)
What does the mating faciliate
H3 acetylation on the OTR gene promoter region in the NAcc, which, in turn, increases the OTR expression and enhances partner preference formation
What has also been implicated in the regulation of pair bonding in prairie voles?
OT in the medial prefrontal cortex (mPFC) of females [8] and lateral septum (LS) of males
Where is pair bonding formed?
ventral pallidum and nucleus accumbens of these species
What are part of the reward system?
Ventral pallidum and nucleus accumbens
What does oxytocin nasal spray improve?
Emotion recognition in young people diagnosed with autism spectrum disorders
What did findings suggest?
potential of earlier intervention and further evaluation of oxytocin nasal spray as a treatment to improve social communication and interaction in young people with autism spectrum disorders
What is MAOA gene
monoamine oxidase A gene and it encodes for monoamino oxidase A which is a protein that is highly expressed from out guts to brain
MAOA gene
linked to aggression in observational and survey-based studies
What does MAOA gene code for?
enzyme monoamine oxidase A that plays a key role in the catabolism of neurotransmitters, including dopamine, norepinphrine, and serotonin
What did earlier studies with MAOA gene show?
mice with MAOA knockouts were more aggressive than their normal counterparts or mice with MAOB knockouts
Who else had also found to have an abnormality in MAOA?
A Dutch family with a repeated incidence of violent criminal behavior among males across several generations
What does recent imaging work in a large sample demonstrates about MAOA?
during emotional arousal, MAOA-L men show greater reactivity in the amygdala and lower activity in the regulatory prefrontal areas. Such work suggests the emotional and cognitive channels that link MAOA-L to impulsive forms of aggression
Pedigree studies of the family
The fragment of X chromosome contained a variety of genes and subsequent mapping of this specific gene that was behind high aggressive trait what happened to be the MAOA gene
What is MAOA promoter?
The promoter of MAOA contains conserved binding sites for Sp1, GATA2, and TBP. This gene is adjacent to a related gene (MAOB) on the opposite strand of the X chromosome
What did the short allele have?
high transcriptional activity and also associated to higher levels of serotonin in CSF In humans
What is MAOA ‘long allele’ versus short allele associated to?
Different activation of Limbic cortex during:
- Cognitive control
- Social rejection
- Response inhibition
- Processing of face
- Differences in gray matter volumes
What does long allele of MAOA gene interpret?
more threat from a face than someone that doesn’t have this particular genetic variant
What does genetic variation start to explain?
Different risks for depression
What does genetic variation in the promoter of 5HT- transporter and MAOA gene alter?
Rates of gene transcription and are correlated with differences in presynaptic 5HTT, and with depression- susceptibility in people that have experienced emotional trauma
What did scientists have managed to identify ?
44 whole genome association hits for depression
What did results from GWAS for major depression show?
- Hits high replication for candidate gene genetic variants
- Hits associated with clinical features of MDD
- Pathways implicate prefrontal and anterior cingulate cortex
- Genes that are targets of antidepressant medication were strongly enriched for MDD hits e.g. 5HTR2a
- Some hits also involved in schizophrenia and autism
