Biological Approach to Behavior

localization of function

the theory that certain areas of the brain are responsible for certain psychological functions

strict localization

the idea that there is a clear correspondence between psychological functions and brain areas, and that all functions can be clearly mapped onto the brain

weak localization

the idea that one brain area may be responsible for a function, but not exclusively, and other areas may also take over the function

widely distributed functions

functions that cannot be localized anywhere in the brain

Broca's aphasia

condition resulting from damage to Broca's area, causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly

Broca's Area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

Wernicke's aphasia

condition resulting from damage to Wernicke's area, causing the affected person to be unable to understand or produce meaningful language

neuroplasticity

the ability within the brain to change itself in response to environmental demands.

cortical remapping

neuroplasticity on the level of the cortex

hippocampus

a part of the limbic system, known to be implicated in emotional regulation

synaptic plasticity

neuroplasticity occurring on the level of a separate neuron, construction of new synaptic connections and elimination of the ones that are not used.

Maguire et al (2000)

looked at human neuroplasticity in a natural setting and demonstrated that London taxi drivers experience significant changes in the relative distribution of grey matter in the hippocampus in response to the demands of the job.

What was the aim of Maguire?

To investigate how the brain structure of London taxi drivers is different from the average brain.

Who were the participants the Maguire study?

16 right-handed male taxi drivers.

Average experience 14.3

Control group-50 healthy right-handed male subjects who did not drive a taxi.

What was the procedure in the Maguire study?

MRI scans were compared between drivers and non-drivers.

Researchers also correlated the number of years of taxi driving experience with results of the MRI scans.

What was the Method used in the Maguire study?

Quasi-experiment; correlation study in the part where driving experience was correlated with grey matter volume. MRI was used to measure the variables.

agonist

a chemical that enhances the action of a neurotransmitter

antagonist

a chemical that inhibits the action of a neurotransmitter

Nuerotransmitter

a chemical messenger stored in the axon and released into the synaptic gap

Selective Serotonin Reuptake Inhibitors (SSRIs)

a class of chemicals that act by preventing reuptake of excess serotonin in the synapse, hence increasing its concentration in the synaptic gap

Neurons

a nerve cell; the basic building block of the nervous system

dendrites

Branchlike parts of a neuron that are specialized to receive information.

Fisher et al (aim)

to investigate neural mechanism of romantic love

Fisher et al (participants)

17 participants who were "intensely in love" with someone, mean age 21 and mean duration of being in love 7 months.

Fisher et al (method)

experiment; repeated measure design. Variables were measure in fMRI scans

Fisher et al (procedure)

Participants were placed in fMRI scanner and went through the following four steps, which were repeated 6 times

-viewing a photograph of the person they love (30 seconds)

-filler activity (40 seconds)

-viewing a photograph of an emotionally neutral acquaintance (30 seconds)

-filler activity (20 seconds)

Brain responses to the pictures of a loved one and the picture of a neutral acquaintance were compared.

Fisher et al (results)

There weas a specific pattern of activation in the brain in response to the photographs of the loved ones. Activation was especially prominent in dopamine-rich brain areas.

Fisher et al (conclusions)

Dopaminergic activity plays a role in feelings of romantic love

CAT Scan

a method of creating static images of the brain through computerized axial tomography

MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy.

fMRI (functional MRI)

A technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.

PET (positron emission tomography)

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

EEG (electroencephalogram)

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

endocrine system

a chemical messenger system of the organism; the system of glands that secrete hormones

Gene knockout (KO)

a genetic technique in which one of the genes of an organism is "switched off"; the term can also be used to describe the organism that carries this inoperative gene

oxytocin

A hormone produced by the hypothalamus and released from the pituitary gland; it is known for its role in social interaction and sexual reproduction.

Cortisol

stress hormone released by the adrenal cortex

pheromone

a chemical messenger that communicates information (such as fertility or sexual attractiveness) from one member of a species to another.

vomeronsal organ (VNO)

a set of receptors, located near, but separate from, the olfactory receptors (in mammals)

accessory olfactory bulb

A neural structure located in the main olfactory bulb that receives information from the vomeronasal organ

main olfactory bulb

the region of the brain responsible for processing smell

DNA methylation

the process by which certain chemicals (methyl groups) are added to the DNA molecule, affecting gene transcription

epigenetic changes

deviations of the phenotype from the genotype occurring as a result of changes in gene expression

gene

a part of the DNA responsible for specific trait or behavior

gene expression

the process of synthesizing organic molecules based on the DNA blueprint; the manifestation of the genotype in phenotypical traits

gene transcription

part of gene expression; replicating the DNA sequence in a freshly synthesized RNA molecule.

gene translation

part of gene expression; decoding the RNA molecule into a sequence of amino acids in a protein

genotype

the set of traits as it is coded in an individual's DNA

phenotype

a set of traits that actually manifest in an individual's body, appearance or behavior

Bouchard

twin studies

Bouchard (aim)

To estimate the heritability of IQ

Bouchard (method)

meta-analysis

Bouchard (participants)

The meta-analysis included 111 twin studies that looked into heritability of intelligence. Participants in these studies included MZ and DZ twins (reared together and apart), siblings (reared together and apart), parents and their offspring.

Bouchard (procedure)

Researchers selected the studies based on a number of criteria, cleaned the data and calculated median correlations between IQ scores of individuals of interest (for example, MZ and DZ twins)

Bouchard (conclusion)

The study demonstrates that intelligence is inherited to a considerable extent (54% according to the Falconer estimate).

At the same time, it is not completely inherited. Even for MZ twins reared together, the correlation between their IQ scores is not perfect, which shows that the environment plays a certain role in the development of IQ.

Caspi et al 5-HTT gene (aim)

To investigate the role of he 5-HTT gene in developing depression in response to stressful life events

Caspi et al 5-HTT gene (participants)

1037 children from New Zealand

Caspi et al 5-HTT gene (method)

A longitudinal study. Genetic mapping was used to divide participants into three groups:

-both short allele of 5-HTT (s/s)

-one short allele and one long allele (s/l)

-both long alleles (l/l)

Caspi et al 5-HTT gene (procedure)

Participants were assessed longitudinally between ages 3 and 26. Two measures were used: a "life history calendar" to assess stressful life events and an interview to assess symptoms of depression.

Caspi et al 5-HTT gene (results)

Participants who had one or two short alleles of 5-HTT (s/l and especially s/s) reacted to stressful life events with more depressive symptoms. For example, participants who had a major stressful life event at age 21 tended to develop depression by age 26, but only if they carried a short allele of 5-HTT

Caspi et al 5-HTT gene (conclusion)

It was concluded that the 5-HTT gene is responsible for modulating an individual's vulnerability to stress.

Weaver et al (2004)

the epigenetics of vulnerability to stress in rats

Weaver et al (aim)

To investigate the epigenetic mechanism in the influence of nurturing on vulnerability to stress.

Weaver et al (participants)

Laboratory-bred rats

Weaver et al (method)

A combination of methods:

-comparison or pre-existing groups (quasi-experiment)

-a rat adoption study

-an experiment, independent measure design

Weaver et al (measuring variables)

-genetic mapping technology, used to determine patterns of methylation of the gene sequence.

-to measure response to stress, rats were placed in a Plexiglass restrainer for 20 minutes. Blood samples were taken before and after this procedure. Corticosterone (stress hormone) was measure in the blood.