Brain, Mind, and Behavior - Exam 2

Parental investment theory

theory that stresses the evolutionary basis of many aspects of parental behavior, including the extensive investment parents make in their offspring (males make less investment than females)

Rene Descartes

17th century French philosopher; put forth concept of dualism, with a separate physical and mental realm. Disproven: think about drinking coffee (physical & mental effects)

Asomatognosia

a deficiency in the awareness of parts of one's own body that is typically produced by damage to the parietal lobe

John Watson

behaviorist; emphasis on learned behavior; famous for Little Albert study in which baby was taught to fear a white rat. FEAR TENDENCIES

Ethology

study of animal behavior in the wild, particularly instinctive behavior

Taste aversions

aversion to food after having eaten it and gotten sick

Thomas Malthus

eighteenth-century English intellectual who warned that population growth threatened future generations because, in his view, population growth would always outstrip increases in agricultural production

Concepts that Darwin knew/believed

- geological structures have natural origins and earth is very old

- populations grow rapidly, resources are limited, hence competition for survival

- species change

- artificial selection (animal breeding) and its implications

Evolution

cumulative change in population characteristics through generations

3 major tenets of evolution

1) changing biota

2) common ancestry

3) mechanism is natural selection

Natural selection

a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

Mechanisms of natural selection

a) Over-reproduction: animals produce more offspring than will live

b) Variation: There are differences among individuals of a species

c) Fitness: some individuals are more suited for survival and reproduction than others

d) Inheritance: Some traits associated with fitness are heritable

Fixed action patterns (instincts)

innate behaviors that are often performed in a stereotypical (same) manner of all members of a species; usually functional in some way; triggered by a cue (sign stimulus) in the environment

Sign stimulus

external sensory stimulus that triggers a fixed action pattern

Imprinting

the process by which certain animals form attachments during a critical period very early in life; often determines adult mating selection; common in prococial animals

Critical period

an optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produces proper development

Precocial young

young animals born in a relatively mature state of development

Altricial young

young animals born in a relatively helpless state (eg. eyes closed)

Newborn prehensile hand reflex

grasping reflex found in human newborns; can actually hold their weight

Yawn contagion

almost reflexive urge to yawn when seeing someone else yawning

Irenäus Eibl-Eibesfeldt

psychologist who established the field of human ethology; compared behavior across many different cultures

Eyebrow flash

behavior found in every culture; exaggerated facial expressions when talking to babies

Paul Ekman

psychologist who studied emotion detection across cultures; certain emotions are universal (anger, disgust, fear, happiness, sadness, and surprise)

Universality of negative emotions vs. positive emotions

the bulk of the data suggest that negative emotions like sadness and disgust tend to look more similar across cultures, whereas positive emotions have more variability across cultures

Fear reflexes

reflexes that stem from fear; includes the startle response and eyeblink reflex

Reproductive reflexes

motor reflexes during sex; certain instinctive attractions (which explains why people wear makeup or have plastic surgery)

Relationship between brain size and intelligence within a species

there is no exact relationship between brain size and intelligence in individuals; however, relative size of different brain groups like the cerebrum in a specific individual does have significance

Relationship between brain size and intelligence between species

neither brain size nor raw proportion of brain to body mass are reliable indicators of intelligence between species; encephalization quotient is used instead

Encephalization quotient

brain size relative to the expected brain size in related taxa

formula: brain weight / (body weight)^0.69

0.69 is the slope of regression line

Cortical convolutions and intelligence

more cortical convolutions tend to correlate with higher levels of intelligence

How we quantify intelligence between species

behavioral sophistication (# of behaviors) and flexibility/adaptability (how they change to respond to environment)

How the brain has changed in human evolution

1) dramatic increase in cerebral volume

2) cortical convolutions have substantially increased

Primary motor cortex

the section of the frontal lobe responsible for voluntary movement; humans have larger regions of the cortex devoted to hands than other primates do

Evolutionary plateau in cerebral volume is caused by

1) Metabolic reasons - brain is already responsible for a large portion of metabolism

2) Birthing becomes significantly harder

3) Lots of DNA already code for the brain (massive genetic demand)

Tyron's rat experiment (maze bright/maze dull)

- experiment where rats that could run mazes quickly and rats that ran mazes slowly were separately bred

- by the 8th generation of rats the distributions of maze running times between the two groups were non-overlapping

- the two groups of rats were also compared in how they responded to enriched or impoverished environments

Effects of different environments on maze bright/maze dull rats

1. Impoverished environment - errors went up for both groups

2. Normal environment - showed most disparity between groups; maze bright rats performed much higher than maze dull rats

3. Enriched environment - errors went down for both groups

Correction to Tyson's rat experiment

later studies suggest that personality traits and anxiety were more important factors than intelligence in determining maze bright/maze dull rats

Minnesota twin study

large study that followed fraternal and identical twins raised together and apart. Compared them on many psychological dimensions. Found that:

- fraternal twins had less correlation than identical twins

- identical twins raised together were more similar than identical twins raised apart

Fraternal twins

twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.

Identical twins

twins who develop from a single fertilized egg that splits in two, creating two genetically identical humans

Heritability coefficient

the proportion of variation between individuals that we can attribute to genes

Turkheimer's findings on twins

among poor families, children who grew up in the same household tended to have similar IQ scores, regardless of how genetically similar they were

Multiplier effect

the effect where genetically similar individuals seek out similar environment (possible confounding factor in twin studies)

London taxi driver study

study in which researchers looked at the brains of London taxi drivers, and found that their hippocampus were larger

Facial symmetry in relation to attractiveness

the degree to which each side of your face precisely matches the other; some studies suggest that humans find it attractive

Polygynous relationships

where one individual (typically the male) has more than one mate at one time; more common with other species; allows the male to pass down his genes to more offspring

Monogamous relationships

where male mates with one female; common for humans, perhaps because human babies are relatively helpless and need more care

Biased operational sex ratio

when sexually ready members of one sex are more abundant than that of another sex; in nature the sex ratio is usually biased towards males, meaning that there are more sexually competing males than females

Epigenetics

a field that is concerned with changes in gene expression by the environment

Mendel's Pea Plant Experiment

using different varieties of the common pea plant, Mendel demonstrated dominant/recessive transmission of various traits

Gene

a unit of inheritance (ex. there's one gene that codes for brown seeds)

Alleles

variant forms of genes that control that same trait (ex. brown seed genes and white seed genes are alleles)

Dichotomous traits

traits that occur in one form or the other, but never in combination (ex. pea plant seeds are always white or brown, never a blend of the two colors)

Genotype

the traits that an organism can pass on to its offspring through its genetic material

Phenotype

an organism's observable traits

Homozygous genes

possessing two identical alleles for a trait

Heterozygous genes

possessing two different alleles for a trait

Dominant genes

the gene of a dichotomous pair that is expressed in the phenotypes of heterozygous individuals; appeared in all first generation offspring of Mendel's experiment

Intermediate genes

occurs when there is incomplete dominance in the heterozygous condition

Recessive genes

the gene of a dichotomous pair that is only expressed in the phenotype of homozygous individuals; appeared in one fourth of second generation offspring of Mendel's experiment

Gene expression

conversion of the information encoded in a gene first into messenger RNA (transcription) and then to a protein (translation)

Gene transcription

the first step of gene expression, in which a particular segment of DNA is copied onto a strand of messenger RNA, which carries the genetic code outside the nucleus

Gene translation

the second step of gene expression, in which the strand of mRNA attaches to a ribosome, which translates the mRNA codons into proteins

Codon

each group of three consecutive nucleotide bases along the messenger RNA strand

Micro-deletions and micro-duplications

when part of a chromosome that usually appears once appears twice or not at all

Mutations

heritable alterations of individuals genes which are caused by errors in replication

Histones

proteins around which DNA is coiled

Histone remodeling (histone acetylation)

the reaction that occurs when histones change their shape and in so doing influence the shape of the adjacent DNA (can increase or decrease gene expression)

DNA methylation

the addition of methyl groups to bases of DNA (can increase or decrease gene expression)

Structural brain imaging

provides information about the basic structure of the brain

Functional brain imaging

provides information about the activity of the brain when people perform various kinds of cognitive or motor tasks

Spatial resolution in brain recording techniques

how precisely a technique allows you to locate neural structures or activity

Temporal resolution in brain recording techniques

how precisely a technique allows you to track when neural activity occurs

Cerebral angiography

a type of contrast x-ray that uses a dye to visualize the cerebral circulatory system (blood vessels) [structural information]

Computed tomography (CT)

a computer-assisted x-ray procedure that can be used to create 3d visualization of the brain and other internal structures of the living body [structural information]

Positron Emission Tomography (PET scans)

a technique for visualizing brain activity, usually by measuring the accumulation of injected radioactive fluorodeoxyglucose (FDG) or 2-DG, which is similar to glucose, in active areas of the brain [functional information]

Magnetic resonance imaging (MRI)

a brain imaging procedure in which high-resolution images are created from a strong magnetic field [structural information; high spatial resolution]

Diffusion tensor MRI

uses water molecules to identify major tracts in the brain [structural information]

Functional MRI (fMRI)

technique that uses magnetic fields to visualize brain activity using changes in blood oxygen level [structural and functional; high spatial resolution, low temporal resolution]

BOLD signal

the signal that is recorded by an fMRI

Functional ultrasound imaging (fUS)

technique that uses ultrasound to measure changes in blood volume in particular brain regions [functional information]

1. cheap

2. highly portable

3. can be used on infants

Electroencephalogram (EEG)

measures of the electrical activity of the brain's surface, commonly recorded through scalp electrodes (doesn't produce image of the brain, just a graph of brain activity) [low spatial resolution, high temporal resolution]

Population/ensemble firing

groups of neurons firing together (EEGs only pick up on population firing)

Typical encephalograms and their psychological correlates

Aroused: low amplitude/high frequency

Relaxed: slightly higher amplitude (alpha waves)

Slow wave sleep: delta waves, massive populations of neurons firing at the same time

Event related potentials (ERPs)

changes in the brain's electrical activity that occur in response to the presentation of a particular stimulus (measured by EEG)

Signal averaging

averaging waves of many EEG recordings where a stimulus was presented; helps reduce background brain activity noise

Magnetoencephalography (MEG)

technique that measures changes in magnetic fields on the surface of the scalp and records ensemble activity directly [high temporal resolution]

Functional Near-Infrared Spectroscopy (fNIRS)

similar to fMRI, estimates brain activity through blood flow associated with neuron behavior; very cheap and small

Psychophysiological measures of nervous system

measures effects of nervous system changes on bodily function

examples:

1. skin conductance

2. muscle tension

3. cardiovascular activity

Methods that perturb function

manipulate neural activity, measure behavior

Examples: neuropsychological patients, TMS, micro-injection, microsimulation

Transcranial magnetic stimulation (TMS)

the use of strong magnets to briefly activate or deactivate brain areas as a way to study brain function

Stereotaxic surgery

the way researchers place experimental devices in precise brain locations

Cannula

micro needle inserted into the brain through stereotaxic surgery and allows for direct infusion of drugs

Bregma

fusion point of 4 plates in skull where all measurements in brain atlas are relative to

Lesions

removal or destruction of part of the brain

Aspiration lesions

lesion in which tissue is suctioned off through a handheld glass pipe (think aspirate and suctioning)

Radio-frequency lesions

lesions in which small subcortical structures are burnt

Reversible lesions

temporary lesions that eliminate the activity in a particular area of the brain while tests are being conducted (lidocaine, muscimol, and optogenetics are common ways to do this)

Optogenetics

technique that involves using viral vectors to insert genes for specialized proteins into neurons. These proteins can then be activated by light in order to excite or inhibit neurons

Optogenetics: channelrhodopsin

protein that allows positive sodium ions into the neuron when it is activated by blue light; excites the neuron