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Heritability & Genetics
Mystery!
Traits and States
Methods
The Brain
100

Name 1 lines of evidence suggesting that it's inappropriate to think of heritability as a single, unchanging, carved-in-stone, universal number or, put another way, that it might be better to think of h2 as a range, rather than a number (discrete "point-estimate")

- variance across samples w/ similar demographics

- variance across lifespan

- variance across human history (female smoking)

- it's a ratio (GV/TTV), and estimates are sensitive to TTV, which is sensitive to social prescriptions, rules, taboos, access to resources, etc. 

100

What is the 4th law of behavioral genetics?

A typical human traits is associated with many genetic variants, each of which account for a very small percentage of variance in the trait.

100

What does recent cross-cultural work tell us about the Big 5?

The Big 5 are relatively similar, but not exactly the same, across human nations, languages, and cultures

100

Like paper-and-pencil surveys, biological measures of T&P need to have what kinds of psychometric properties?

  • adequate construct validity (a.k.a. psychological sensitivity and specificity) 
  • adequate internal-consistency reliability
  • sufficient test-retest stability (trait-like)
100

Are trait-like differences in T&P discernible in the on-going, spontaneous activity of the brain?

Yes!

200

Are all human behaviors heritable and/or biological?

  • Nearly every aspect of human behavior is somewhat heritable and reflects the structure/function of the brain; all behaviors are “biological”
  • put another way, if a scientist crows about "new evidence that practicing mindfulness or training cognition or learning to play the piano leads to changes in the brain," you are justified in saying "duh; how else could long-lasting changes in thoughts, feelings, and actions occur?! i mean c'mon. what are you, a Dualist?" 
200

TRUE OR FALSE?

  • Teen snares completely explain the negative adult outcomes (reduced health, wealth, public safety) experienced by many kids with low C/SC; therefore, we can wait to intervene until the teen years #MoffittCaspi #Dunedin #Self-Control

FALSE.

200
  • Describe how traits and states are related in a way that is consistent with the Endogeous/Tonic model? name 2 lines of evidence

trait questionnaires predict emotional states to emotionally-neutral emotion induction procedures (e.g. neutral film clips, screen savers)

Trait questionnaires (e.g. N/NE) predict state questionnaires (acute negative affect, distress) in the absence of a specific emotional challenge

200

EEG, fMRI, and invasive neuronal recordings are:

causal? 

correlational?

mechanistic?

correlational!

200
  • Imaging technique A is characterized by a small number of large voxels; Imaging technique B is characterized by a large number of small voxels (more measurements). Which technique has better temporal resolution?

Unknown

300

(a) What is heritability AND (b) is it synonymous (the same as) genetically programmed .... meaning: can you have traits or phenotypes that built according to genetic recipes, yet have a heritability of ~0/undefined?

  • Genetic variance divided by total trait variance (GV/TTV)
  • The proportion of variation in a trait, such as height or C/SC, that can be predicted knowing how the trait looks in blood relatives
  • A population measure that does not apply to any individual
  • H^2 is not the same as genetics; e.g. 10 fingers, 2 arms
300

Samiha hypothesizes that: (a) individuals with High-N/NE differ in their implicit processing of emotional facial expressions. She believes that (b) this is an automatic process that occurs in the visual cortex in <300 milliseconds. Which measure might she use to test her model?

  • Event-related potentials
300

How do individuals with high N/NE react to threat compared to individuals with low N/NE? 

Show elevated reactions to threat (bigger peak, slower recovery)

300

How might you measure whether or not N/NE reflects differences in the tonic activity—the ‘baseline hum’—of a small, subcortical region of the brain?

  • ASL/perfusion fMRI or FDG-PET
300

What do genes code for?

Proteins which in turn make up neurons

400

How does experience (e.g. maternal nurture) get 'under the skin' and produce long-lasting differences in emotional traits? 

Changes in the epigenome alter the expression of genes --> leading to changes in protein synthesis --> changes in brain structure and function (glu receptors in the hippo; BDZ receptors in the amygdala) --> persistent alterations in behavior and stress reactivity [Meaney]

400

A) Amygdala metabolism predicts trait-like individual differences in dispositional anxiety (anxious temperament) in what 2 kinds of contexts?

B) why is this scientifically or "theoretically" interesting?

C) What's the major caveat or limitation of "B" 

  • A) In stressful contexts (alone in the novel testing cage, human intruder) & In secure contexts (home cage alone, home cage with cagemate)
  • B) Latter suggests that emotional traits are evident in the brain's activity in the absence of a trait-relevant challenge (threat)
  • C) had to inject the monkey w 18-FDG...so not quite the same as lying at home on the couch daydreaming 
400

name a key piece of evidence supporting the phasic/interactive/gas-matches-fire model of traits and states

  • High-N/NE subjects report exaggerated distress and negative affect in response to aversive film clips, compared to Low-N/NE subjects
400

What is a strength of EEG and Event-related potentials (ERPs)? Name at least 2 strengths...

  • Excellent temporal resolution (milliseconds), making it possible to dissect the stream of sensation-perception-cognition into its constituent processes
  • EEG is cheap, tolerant of motion, and reflects neuronal electrical activity
  • Can be used in ambulatory settings
  • No radiation; can talk; silent; no issues w/ claustrophobia
400

Where do individual differences in brain structure and function come from?

Genome/DNA

Experience

Experience interacting with the epigenome to alter gene expression and protein synthesis 

500

Is a large GWAS, incorporating >100,000 subjects were to identify a SNP that predicts a small but significant % of variance in a trait or phenotype (e.g. N/NE, cholesterol, height, blood pressure) a worthwhile endeavor? Why or why not?

yes! It may be worth testing in an animal model (e.g. fruit flies, zebra fish, mice) because “% of variance” tells us nothing about mechanistic or causal importance (for example, when manipulated using a drug)

500

Describe 3+ features of High-BAS individuals.

#Gray #Davidson #Gable

- appetitive motivation; work to approach rewards and reward-related cues

- approach-related pos affect

- approach-related neg affect / anger when goal is thwarted

- L >> R frontal EEG asymmetry

- tend to experience elevated levels of PA in daily life

- tend to experience/report more freq pos events in daily life

- Gable showed that the increased freq of PE's partially explains the elevated levels of PA, reminding us that the impact of traits (BAS) on states (PA) can be mediated by differences in motivated behavior (drive to reward; mildly extraverted behaviors)

500

Are particular traits, such as N/NE, GOOD or BAD?

neither! e.g. in some environments (e.g. genuinely dangerous contexts), N/NE is likely to be protective and keep the individual safe from danger. the key thing is the fit between the trait and the environment

500

What's problematic about unpublished null results (the so-called ‘file drawer problem’)?

Unpublished null results bias scientific literature, such that narrative reviews and quantitative meta-analyses systematically over-estimate the size of an effect (such as the association between N/NE and amygdala reactivity or likelihood of developing depression)

500

Is the serotonin transporter polymorphism (5-HTTLPR) actually related to serotonin levels or receptors in the amygdala?

no!