biological approach

A principle

A broad assumption that guides research in a certain area.

The principles of the biological approach

1. Behavior is the product of physiology.
2. Behavior can be genetically inherited.
3. Animal research may inform our understanding of human behavior.

Holism, or the holistic approach

A methodological position that attempts to gain understanding of the whole in all its complexity. It claims that the whole is bigger than the sum of its parts.

Reductionism, or the reductionist approach

An attempt to explain a complex phenomenon by
its constituent parts. It may be understood as
reducing the whole to its parts.

Localization of function

The notion that every behavior has its specific place
in the brain and is associated with a certain brain area.

Neurons

Cells that perform the function of communication in the body.

The nervous system

A system of neurons.

Components of the central nervous system

The spinal cord and the brain.

The four major parts of the human brain

The cortex, cerebellum, limbic system, and the brain stem.

The cortex

The layer of neurons with a folded surface covering the brain on the outside - it is the largest part of the human brain and is associated with higher-order functions such as abstract thought or voluntary action.

The four lobes of the cortex

Frontal, parietal, occipital, and temporal lobes.

The frontal lobes

Associated with reasoning, planning, thinking and decision-making,
voluntary action, complex emotions, and so on.

The parietal lobe

Associated with movement, orientation, perception and recognition.

The occipital lobe

Associated with visual processing.

The temporal lobes

Associated with processing auditory information, memory and
speech.

The two divisions of the cortex

The left and right hemispheres

The corpus callosum

The structure of neurons that connects the two hemispheres of the cortex.

The cerebellum

'The little brain' - two hemispheres and a folded surface, and is associated with coordination of movement and balance.

The limbic system

'The emotional brain' - An evolutionarily older subcortical structure that includes several sub-structures.

The structures of the limbic system

The thalamus, hypothalamus, amygdala, and the hippocampus.

The thalamus

Associated mostly with sensory functions. Nerves from almost all sensory organs reach the thalamus as a final “hub” before they are connected to the cortex.

The hypothalamus

“Below” the thalamus in the brain and it is involved in such functions as emotion, thirst and hunger.

The amygdala

Involved in memory, emotion, and fear.

The hippocampus

Important for such functions as learning, memory and transferring short-term memory to a more permanent store, spatial orientation.

The brain stem

Underneath the limbic system, and its main function is to regulate the basic vital processes such as breathing or heartbeat.

Strict localization

The idea that specific parts of the brain are solely responsible for specific functions.

Relative localization

The idea that specific parts may be responsible for certain functions, but not exclusively - other parts may also assist in the functioning.

Neuroplasticity

The ability of the brain to change throughout the course of life through the making and breaking of synaptic connections between neurons.

Synaptic plasticity

The ability of the neuron to form new synaptic connections and break up the old ones.

Cortical remapping

Neuroplasticity on the largest scale - the phenomenon when
brain area X assumes the functions of brain area Y,
for example, due to injury.

Synaptic activity is dependent on...

The activity of neurons.

The effect of neuron activity on synaptic activity

If two nearby neurons are frequently activated at the same time, a synaptic connection between them may gradually form. Similarly, if two neurons are rarely activated together, the existing connection may gradually fall apart.

The 'brain mechanism of learning'

Neuroplasticity.

The mid-temporal area of the cortex

Areas known to be implicated in coordination of movement.

The three parts of a neuron

The soma, dendrites, and axon.

The soma

The body of a neuron.

Dendrites

A neuron's appendages that are designed to receive communications from other cells.

The axon

The extension of the soma that has the function of transmitting signals further.

The function of both the soma and dendrites

To receive signals from other neurons.

The function of the axon

To transmit signals further.

The location of synapse formation

Where the axon of one neuron approaches a dendrite or soma of another neuron.

Synapse, or synaptic gap

A structure that connects two neurons.

Threshold of excitation

The level of neural excitation (or depolarization) that is necessary to generate an action potential.

Action potential

A brief pulse called that travels along the axon to other neurons, passing the excitation further.

The mechanism of transmission becomes chemical at...

The end of the axon, at the synaptic gap.

A neurotransmitter

A signaling molecule secreted by a neuron to affect another cell across a synapse.

Axon terminal

The part of a nerve cell that makes synaptic connections with another nerve cell.

The location of neurotransmitter synthesis

The neuron.

The location of neurotransmitter storage

The axon terminal.

The location of neurotransmitter release

The synaptic gap.

The three possible fates of a released neurotransmitter

Metabolized (destroyed), reuptake, or binding to the receptors of the next neuron.

Reuptake

The reabsorption of a neurotransmitter by a neurotransmitter transporter located along the plasma membrane of an axon terminal after it has performed its function of transmitting a neural impulse.

The location of neurotransmitter binding

The receptors on the post-synaptic membrane.

The two types of neurotransmitters

Excitatory and inhibitory.

Excitatory neurotransmitters

Neurotransmitters that allow the impulse to cross the synapse and
produce stimulating effects on the brain.

Inhibitory neurotransmitters

Neurotransmitters that stop the impulse, preventing it from crossing the synapse, producing calming effects on the brain.

Excitatory and inhibitory neurotransmitters are always in a state of...

Dynamic balance.

The implications of neurotransmitters out of optimal ranges

Possible behavioral malfunctions and mental disorders.

Chemicals that influence neurotransmitters

Agonists and antagonists.

An agonist

A chemical that enhances the action of a neurotransmitter.

An antagonist

A chemical that counteracts a neurotransmitter and so prevents a signal from being passed further.

An example of an antagonist

SSRIs (selective serotonin reuptake inhibitors).

SSRIs (selective serotonin reuptake inhibitors)

A class of drugs that selectively inhibit (block) the reuptake of the
neurotransmitter serotonin from the synaptic gap. This increases the concentration of serotonin in the synapse.

A placebo

An inactive substance that looks like the drug or treatment being tested.

Serotonin

A neurotransmitter with the biological function of modulating mood, cognition, reward, learning, memory. Serotonin may help prevent depression.

Neuroimaging, or brain imaging techniques

A discipline that studies the structure and function of the nervous system by means of imaging technology, and where the images of the brain can be obtained in a non-invasive way.

The five most common neuroimaging techniques

Computerized axial tomography (CAT), positron emission tomography (PET), magnetic resonance imaging (MRI), functional
magnetic resonance imaging (fMRI), and electroencephalography (EEG).

fMRI

A neuroimaging technique that measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.

The resolutions involved in fMRI

Spatial and temporal resolution

Spatial resolution

The ability to discriminate between nearby locations: just as with the resolution of your computer screen, the lower it is, the more pixelated the picture and the less detail you can discern.

Voxel

The unit of measurement of fMRI.

Temporal resolution

The smallest time period in which changes in brain activity can be registered. Can be thought of as the rate at which snapshots of the
brain are taken—“frames per second”.

Advantages of fMRI usage

Non-invasive, does not involve radiation, and enables the detection of abnormalities of the brain, as well as the assessment of the normal functional anatomy of the brain.

Disadvantage of fMRI usage

Expensive in comparison to other scanning techniques, patient movement can affect the quality of images, and is not suited for studying instantaneous processes such as information travelling from the retina to the visual cortex due to the need for several seconds of activity.

Hormones

A class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior.

The location of hormone secretion

The endocrine glands.

Parts of the endocrine system

Adrenal glands, hypothalamus, pineal gland, pituitary gland, thyroid, parathyroid, thymus, pancreas, testes and ovaries.

Differences between hormones and neurotransmission

1- Hormones are released into the bloodstream and travel with blood to reach their destination. Conversely, neurotransmission is communication along nervous cells.
2- The nervous system regulates relatively rapid processes (movement, emotion, decisions, and so on), whereas hormones can regulate long-term ongoing processes such as growth, metabolism, digestion or reproduction.
3- The degree of voluntary control over neural regulation is higher than over hormonal regulation.

The relationship between the nervous and endocrine systems

Interdependent

Target cell

A cell that has the receptors for a particular hormone and can thus be influenced by it, making it the target cell of the hormone.

The possible genomic changes caused by hormones

Gene activation and gene suppression.

Gene activation

The process of activation of a gene so that it is expressed at a particular time.

Gene suppression

The regulation of gene expression in a cell to prevent the expression of a certain gene.

Chromosomes

A thread-like structure that contains a DNA molecule. The long DNA molecule is tightly coiled many times around supporting proteins, so a chromosome is a “package” that contains folded DNA.

An allele

One of two or more versions of DNA sequence at a given genomic location.

Genotype

The set of traits as coded in an individual’s DNA.

Phenotype

An individual's observable traits as determined by both their genomic makeup (genotype) and environmental factors.