Biological Bases of Behaviour

Ngl this unit was one of the hardest units for me along with developmental psychology. This chapter is also so long so like suffer with me.

Nature-nurture issue*

The longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors.

Basically, do genetics or environment contribute to psychology more?

Today's science sees traits and behaviors arising from the interaction of nature and nurture

Everything psychological is simultaneously biological

Natural Selection

The principle that inherited traits that better enable an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations

Darwin proposes that nature selects the genetic variations which help us to pass on our genes and survive in our environments

Many predisposed behavioural patterns are no longer aligned with survivability and fitness today

Mutation

A random error in gene replication that leads to a change

Evolutionary psychology

The study of the evolution of behavior and the mind, using principles of natural selection

Helps us understand human behaviour and mental processes

Can help explain some behaviour but are not as restrictive in humans as other species

Genes and environment both interact and contribute to our fitness - our ability to survive and reproduce

Behaviour genetics

The study of the relative power and limits of genetic and environmental influences on behaviour

Environment

Every non-genetic influence, from prenatal nutrition to the people and things around us

Heredity

The genetic transfer of characteristics from parents to offspring

Behaviour geneticists

Focus on how genes and the environment contribute to differences in behaviour and mental processes

Main questions is how much of who we are is a product of heredity or of our environment

Environmental influences are external; Heredity is internal.

Genes

The biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein

In normal development, humans receive 23 chromosomes from each parent

Each chromosome is made of DNA, which is made up of genes

Genes are also influenced by the environment

Genome

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

Small variations can do big changes, like how every race of people are 95% similar

Identical (monozygotic) twins

individuals who developed from a single fertilized egg that split in two, creating two genetically identical organisms

DNA is exactly the same as each other

Fraternal (Dizygotic) twins

Individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but shared a prenatal environment.

No more genetically related than regular siblings

(Separated) twin studies*

Used by researchers to point out the similarities in identical twins raised in different environments

While genes influence personality traits (extrovert, introvert, etc), environment influences attitudes, values, manners, faith, and politics

Adopted twins' personalities are more like their biological parents rather than their adoptive ones

Interaction

The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity)

A main topic of modern psychological research

Differences can result from environment but connects to adaptation

Gene-environment interaction investigates a variety of topics including mental and physical health issues

Epigenetics

"above" or "in addition to" (epi) genetics; the study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change).

How heredity and environment work together

Environments can trigger or block genetic expression.

Genetic markers direct genes to be 'turned off or on'; these markers are influenced by environmental factors such as diet, stress, and drug use.

Childhood trauma, poverty, and stress from war may have long lasting effects on a person's genes.

Bottom line: Nature via nurture

Nervous system

The body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems

Whole body communicates with itself

Nervous system is made up of neurons that use neurotransmitters to communicate between areas

Neurons

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

Send messages, process information, make decisions, and send signals to execute commands throughout the body

Central Nervous System (CNS)

Consists of the brain and spinal cord

Thinking, feeling, and acting must all be routed through the CNS, through millions and millions of neurons communicating with each other

Peripheral Nervous System (PNS)

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

Helps the CNS to communicated with the rest of the body by transmitting sensory information to the brain and delivering commands to muscles and glands

Nerves

Bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sensory organs

Sensory (Afferent) neurons

Neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord

SAME

Sensory Afferent, Motor Efferent

Bring messages from the sensory receptors to the CNS for processing

Motor (Efferent) neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Carry commands of response back out to the muscles and glands of the body to act in response to stimuli

SAME

Sensory Afferent, Motor Efferent

Interneurons

Neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs (connect afferent and efferent neurons)

Process all incoming information and then make decisions about what responses would be appropriate

Millions of Afferent and Efferent neurons but billions of these

Somatic (skeletal) nervous system

Enables communication from the brain and spinal cord to our muscles connected to bones. Responses are carried out by this part of the PNS by motor neurons

Autonomic nervous system

Controls self-regulated action of internal organs and glands

Is further divided into 2 divisions

Sympathetic nervous system

Arouses the body, prepares it for fight or flight at a time when there may be danger

Parasympathetic nervous system

Calms the body down and brings it back to a normal resting state after an arousal producing event has passed

Neural networks

Clusters of neurons that layer together to work on connected tasks

Neurons that are constantly in communication with each other become stronger in their connections

Reflex

Simple, automatic response to a sensory stimulus such as the knee-jerk reflex

Spinal cord

Connects the peripheral nervous system to the brain and facilitates communication between the two. It also processes reflexes independently of the brain.

Reflex Arc

The neural pathway that mediates a reflex action, involving sensory neurons, interneurons, and motor neurons.

Cell Body

The part of a neuron that contains the nucleus; the cell’s life support system. It integrates incoming signals and generates outgoing signals to the axon.

Dendrites

Neuron’s bushy branching extensions that receive and integrate messages, conducting impulses towards the cell body and plays a crucial role in neuronal communication.

Axon

The segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands. It is responsible for transmitting electrical impulses away from the cell body and can be covered by myelin sheath to enhance signal speed.

Myelin Sheath

A fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next

However, after the age of 25, myelin starts to degenerate, which leads to slower reaction time.

Multiple sclerosis has been linked to extreme deterioration

Glial cells

Cells in the nervous system that support, nourish, and protect neurons

Also play a role in learning, thinking, and memory

Serve neurons by feeding them, creating myelin for insulation, guiding connections, and cleaning up the environment in which neurons live

Action potential

A neural impules or a brief electrical charge that travels down an axon.

They are the means of communication between neurons

A brief electrical charge is rushed down the axon by opening a series of gates that allow positive ions to rush in and create depolarisation

Neuron will fire action potential if excitatory impulses outnumber inhibitory ones.

After firing, every neuron must rest during a refractory period before it fires again

Threshold

The level of stimulation required to trigger a neural impulse; it is the point at which a neuron will fire an action potential.

Refractory period

A brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

All or none response

A neuron’s reaction of either firing with a full strength response or not firing. No in-between

Synapse

The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron.

The tiny gap of this junction is called the synaptic gap or synaptic cleft

Neurotransmitters

Chemical messengers that cross the synaptic gap between neurons

When released by the sending neuron, they travel across the synapse and bind to receptor sites on the receiving neuron which influences whether or not the neuron will generate a neural impulse

Reuptake

A neurotransmitter’s reabsorption by the sending neuron

Endorphins

“Morphine within”; natural opioid-like neurotransmitters linked to pain control and pleasure

Also released when we partake in vigorous exercise

Acetylcholine (ACh)

Best known to influence learning, memory, and muscle action

Agonist

A molecule that increases a neurotransmitter’s actions

Mimic a neurotransmitter, blocks reuptake, and/or increases production

Antagonist

A molecule that inhibits or blocks a neurotransmitter’s actions

Block receptor sites, decrease production, and release neurotransmitters

Endocrine system

The body’s “slow” chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream

Body’s second system of communication that uses hormones instead of neurotransmitters to influence behaviour and emotions

Some hormones are identical to neurotransmitters, but travel through the body at slower speeds

Autonomic nervous system controls the adrenal glands

KING GLAND IS THE PITUITARY GLAND THAT CONTROLS AND INFLUENCES ALL OTHER GLANDS!!!

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

Epinephrine/Norepinephrine

Fight or flight response - released by adrenal glands

Psychoactive drug

Chemical substance that alters the brain, causing changes in perceptions and moods

Used by many daily like caffeine, alcohol, and nicotine

Substance use disorder

Disorder characterised by continued substance use despite life disruption

Tolerance

Diminishing effect with regular use of the same dose of drug

Will require the user to take larger and larger doses before experiencing the drug’s effect

Addiction

An everyday term for compulsive substance abuse that continue despite harmful consequences

Withdrawal

Discomfort and distress that follow discontinuing an addictive drug or behaviour

Stimulants

Drugs that excite neural activity and speed up body functions

Caffeine is a commonly used stimulant

Nicotine is also delivered through cigarettes and vaping products and is a lead cause of preventable death (7 million casualties annually) it also corresponds to depression and chronic disability

Cocaine is also highly addictive and is smoked, snorted, or injected, which causes a rush of euphoria. It results in increased aggression, inflated confidence, emotional disturbances, and cardiac arrest

Depressants

Drugs that reduce neural activity and slow body functions

Alcohol is a commonly used depressant

Memory disruptions and less REM sleep are also depressing effects of alcohol

Barbiturates

Drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgement

Alcohol and barbiturates combined are deadly

Overdoses are common

Opioids

Opium and its derivatives; depress neural activity, temporarily lessening pain and anxiety

Examples: heroin, oxycontin, morphine, and fentanyl

Hallucinogens

Psychedelic (“mind manifesting”) drugs distort perceptions and evoke sensory images in the absence of sensory input

They tend to follow patterns where they are provoked by drugs, loss of oxygen, or even a near-death experience

Can be synthetic like LSD and MDMA or organic like psilocybin or ayahuasca

Can be used to treat PTSD disorders

Marijuana contains THC and produces a mix of effects, but can be used in medicinal purposes

Near-death experience

Altered state of consciousness reported after close brushes with death; similar to drug-induced hallucinogens

Picture of substances in case y’all are confused

Biological psychology

The scientific study of the links between biological (genetic, neural, hormonal) and psychological processes

History:

Hippocrates correctly located the mind in the brain

Franz Gall incorrectly believed that the outside of the skull with its cavities were connected to function - he did reveal that the brain functions are regionalised but on the inside, not on the outside

Biopsychosocial approach

An integrated approach that incorporates biological, psychological, and social-cultural levels of analysis

Each biological system is part of a subsystem that makes up the whole person who in turn lives within family, community, and culture

Levels of analysis

The differing complementary views, from biological to psychological to social-cultural, for analysing any given phenomenon

Neuroplasticity

The brain’s ability to change, especially during childhood, by reorganising after damage or by building new pathways based on experience

Practice of information or skills can lead to changes in the brain associated with habitual tasks

Part of what makes humans exceptional at adapting to a constantly changing world

Lesion

Tissue destruction

Brain lesions use the brain’s ability to change, especially during childhood, by reorganising after damage or by building new pathways based on experience

Parts of the brains can be stimulated or lesioned in order to observe effects

EEG (electroencephalogram)

An amplified recording of the waves of electrical activity sweeping across the brain’s surface.

These waves are measured by electrodes placed on the scalp

Shows electrical activity patterns of a brain at work

MEG (magnetoencephalography)

A brain imaging technique that measures magnetic fields from the brain’s neural activity

Isolates magnetic fields generated by the brain during tasks and can show how this task affects brain activity

CT (computed tomotography) scan

A series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain’s structure

Shows structural damage such as after a brain injury

PET (Positron emission tomography)

A technique for detecting brain activity that displays where a radioactive form of glucose goes while the brain performs a given task

Following radioactive glucose trackers to identify active areas of the brain

MRI (magnetic resonance imaging)

Technique that uses magnetic fields and radio waves to produce computer generated images of soft tissue (shows brain anatomy)

No radiation

Can also identify enlarged or damaged areas of the brain

fMRI (functional MRI)

A technique for revealing blood flow and therefore brain activity by comparing successive MRI scans

Shows brain anatomy AS WELL AS structure

Hindbrain