ib exam review

MRI scans

uses magnetic field and radio waves to map the activity of hydrogen molecules, which are present in brain tissue

gives high resolution, 3D pictures of the brain that can be viewed as a “slice” from any angle

maguire et al

MRIs on London taxi drivers for density and area of grey matter in hippocampus using VBM and pixel-counting, compared to control

larger posterior (spatial memory) and smaller anterior hippocampus (encoding new stuff) in taxi drivers

localization of function

specific parts of the brain are for specific behaviors

processes are “localized to distinct brain regions” but the regions interact with each other for cognitive tasks (distributive processing)

neuroplasticity

brain alters/adapts structure due to internal/external changes

structural NP = changes caused by experiences/memories

repetition of tasks causes neuroplasticity (long term potentiation)

neurotransmitters/acetylcholine (ACH)

allow an impulse to cross a synapse (excitatory) or stop the impulse/prevent it from crossing (inhibitory)

ACH plays a role in memory consolidation in the hippocampus

affected by antagonists which reduce their effect

ex scopolamine blocks ACH receptors

neurons working together can produce a large variety of effects resulting in a complex repertoire of behaviors

ex memory consolidation in the hippocampus

antonova et al

injected with scopolamine or placebo and played VR game needing spatial memory to find pole while getting fMRI scanned

less hippocampal activation when injected with scopolamine → ACH plays key role in encoding of spatial memories

undue stress/harm

greater than everyday life, not simple discomfort/embarrassment, must leave experiment in same condition as when entering

lab experiment

highly controlled, manipulate IV, measure DV, no confounding variables, control group, random allocation of participants, causation

antagonist/scopolamine

block receptor site of neurotransmitters, stops impulse from crossing synapse

ex scopolamine (drug) is antagonist for ACH which plays role in memory consolidation in hippocampus

neural network formation

repeated neural stimulation increases synaptic strength

new dendrites grow, expanding the number of synapses available for behavior and increasing density in specific brain regions (dendritic branching)

leads to neuroplasticity

draganski et al

MRI scan pre-experiment, half learned to juggle then second MRI after mastery, didn’t juggle for 3 months then 3rd MRI scan

jugglers had more grey matter in mid-temporal area but same amount after 3 months

neural pruning

synapses are overproduced and some are rarely used/aren’t helpful so the brain eliminates/”prunes” them to strengthen useful/active connections

agonist

substance that binds to neural receptors and activates them

all neurotransmitters are endogenous agonists

ex ACH is an agonist for ACH receptor sites

excitatory synapse

specialized junction between neurons where neurotransmitters are released

increases likelihood of a neuron firing by depolarizing the neuron

ex ACH binds to nicotinic ACH receptors, allowing for encoding of new info and memory consolidation

hormones/cortisol

secreted by endocrine system directly into the blood stream

can increase or decrease function of target cells

cortisol is secreted by the adrenal glands in response to physical or psychological stress

provides the energy that is an important part of the "fight or flight” response

low levels are beneficial but high levels can impair memory retrieval and lead to hippocampal impairment

newcomer et al

tablet of 0, 40, and 160 ,g cortisol (placebo, low, or high level) for 4 days and listened/recalled paragraph pre and post consumption day 1, 4, and 6

40 mg had best recall than 0 then 160

pheromones/evolutionary/MHC

natural selection: mates with the best gene pool are chosen to be passed down through generations

MHC plays role in immune system, more diverse MHC = stronger immune system of offspring

expressed co-dominantly and through body odor

wedekind et al

typed for MHC, men slept in t-shirt for 2 days then women ranked smell of 7 t-shirts for odor intensity, pleasantness, and sexiness from 1-10

odors scored higher when MHC was different

reversed when women took oral contraceptives

role of 5-HTT

diathesis-stress theory: individuals in stressful environments with specific genetic predispositions will have expressed genes

5-HTT: serotonin transporter gene, influences serotonin reuptake in the brain and is associated with depression vulnerability

caspi et al

3 groups from 5-HTT alleles (s/s, s/l, l/l) assessed for depression and filled out stressful life events questionnaire for frequency of 14 events between 21-26

participants with 1+ s allele had more depression symptoms if 3+ stressful life events, more stressful life events = more depression symptoms

twin studies

monozygotic twins are genetically identical (1 egg), dizygotic twins share 50% of genes (2 eggs)

concordance rate: probability that the same trait is present in both twin members

can evaluate degree of genetic and environmental influence on a trait

kendler et al

swedish twin pairs, telephone interviews for major depressive disorder

higher concordance rates in MZ than DZ twins and women than men

quasi experiment

participants are grouped based on trait/behavior, measure DV, no confounding variables, control group, highly controlled, causation