AP Psychology

Biological Bases of Behavior

action potentialAction potential refers to the firing of a neuron. This occurs when the charge inside the neuron becomes more positive than the charge outside.

all-or-nothing principleThe concept of the all-or-nothing principle (or law), first used to look at reactions in the heart, say that the strength of the stimulus has no connection to whether a nerve or muscle fiber will react. As long as the stimulus exceeds the threshold potential, the nerve or muscle fiber will react fully. If it does not exceed the threshold potential, the fiber will not react at all.

autonomic nervous system (ANS)sympathetic and parasympathetic nervous systems

The autonomic nervous system (ANS) is the part of the peripheral nervous system that controls internal biological functions.

The ANS is made up of two parts: one, the sympathetic nervous system preps the body to deal with dangerous or stressful situations by speeding up the heart rate and increasing oxygen intake. Blood flow is sent to those parts of the body that needs it the most; two, the parasympathetic nervous system, in contrast, conserves energy and helps the body recover from strenuous activity.

behavioral geneticistsA behavioral geneticist is one who looks at genetics and environment to explain behavior. Such things that can be explained accordingly include personality, intelligence, disorders and even what determines what we eat and how we choose to find a mate.

This science is a product over the discussion of nature-nurture debate that, by the 1970s, was determined that both genetics and the environment impact human behavior and actions.

brain: convolutions, gyri, sulci, contralaterality

Animals with big brains, like humans, developed to pack as much matter in the brain cavity as possible. To do so, the cerebral cortex became wrinkled –these wrinkles are collectively known as convolutions. The grooves made by the wrinkles are called sulci and the ridges are known as gyri.

Contralaterality is the idea of one side of the brain controlling the other side.

brain functions: amygdala

A part of the frontal lobe, the amygdala is one of the basal ganglia within the limbic system. It is thought that it controls motivation and emotion. Some theorize that it also might contain memories of recent events.

Others have suggested that the amygdala might influence sexual orientation, social ability, aggression, fear and even binge drinking.

brain functions: association areas

The association areas can be found in the cerebral cortex where there is an integration of the motor and sensory functions. However, the association areas deal more with sensory information processing and multi- and sensorimotor integration.

brain functions: basal ganglia

The basal ganglia are clusters of neurons located deep within the brain. They are responsible for regulating the start of movements, balance, eye movements and one’s posture. They are located on either side of the thalamus. These clusters include the caudate nucleus, putamen, globus pallidus and substantia nigra.

If these clusters are over-active, they can create issues such as obsessive compulsive disorder (OCD) and if underactive, can create issues such as depression.

brain functions: cerebellum

The cerebellum is behind the spinal cord and responsible for posture, balance and other voluntary movements.

brain functions: cerebral cortex

The cerebral cortex is the outer layer of the forebrain; gives one the ability to learn and store information and abstract thoughts

brain functions: hippocampus

As a part of the limbic system and according to early doctors, looking like a “seahorse” (hence its name), the hippocampus allows for the accumulation of long-term memories. If there is damage to the hippocampus, this could lead to amnesia.

brain functions: hypothalamus

Ok, this part of the brain does a great deal. The hypothalamus controls hunger, thirst, sexual behavior and reactions to temperatures. It also activates the sympathetic and parasympathetic systems as well as the release of hormones from the pituitary gland.

brain functions: medulla oblongata

The medulla oblongata is a part of the brainstem the regulates respiration, blood circulation, heart rhythms and digestion. Its nuclei regulates vomiting, swallowing, coughing and sneezing.

brain functions: ponsThe pons bridges the gap between the brain and the spinal cord, where messages are transmitting. It is responsible for activating the systems for arousal and awareness.

brain functions: thalamusThe thalamus integrates sensory input, such as vision, hearing, taste as well as skin sensation.

central nervous system (CNS)The central nervous system (CNS) is made up of the brain and the spinal cord.

The spinal cord is a series of nerves that run along the spine and transmit messages between the body and the brain.

The body provides protection for both the brain and the spinal cord nerves in order to protect its functioning. Any damage to the spinal cord could result in paralysis.

cerebral cortex lobes: aphasia

Aphasia is a condition where a person has lost the ability to speak or to understand speech. This typically happens after some trauma or damage to the brain, particularly the frontal and temporal lobes. Speech therapy has been helpful but other areas of the brain have also been seen taking on the language functions to compensate.

cerebral cortex lobes: Broca’s areasLocated in the frontal lobe, the Broca’s areas are associated with the ability to speak.

cerebral cortex lobes: frontal lobesThe frontal lobe is responsible for the planning of movements and working memory (recent memory). Additionally, it interprets and controls emotional behavior, is responsible for decision making and the aforementioned carrying out of action. It is the largest of the five lobes.

cerebral cortex lobes: glial cells

In support of the nervous system, the glial cells help guide the development of neurons. In so doing, these cells nourishes them, sheds waste and protects the neurons.

cerebral cortex lobes: occipital lobes

Located in the back of the cerebral cortex, the occipital lobes are responsible for vision.

cerebral cortex lobes: parietal lobes

Located at the top of the cerebral cortex, the parietal lobes are responsible for processing information related to body sensations such as touch, temperature and pain.

cerebral cortex lobes: temporal lobes

Along the side of the cerebral cortex, the temporal lobes deal primarily with hearing, language comprehension (Wernicke’s area) processing sound and smell. There are also some association areas for memory and learning.

chromosomeChromosomes are the structure of cell nuclei in which can be found the genes that are determined by the DNA sequences. All species have a certain number of chromosomes with humans having 23 pairs.

chromosome: albinismAlbinism is a recessive trait that does not produce pigment (giving people a pale, ashen appearance), can cause the rapid quivering of the eyes (which tend to be pink or red), photophobia (extreme sensitivity to light) and a lack of depth perception. Worldwide, it happens to one in twenty thousand individuals.

chromosome: color blindnessThis inherited sex-link trait, which is more common in males, refers to the inability to see certain colors, most commonly red or green. Completely color-blind individuals can only see black, white and shades of gray. While this condition can keep people from doing various jobs, piloting among them, it does not effect one’s ability to see.

chromosome: dominant gene

A dominant gene is one that is expressed when paired genes are heterozygous (different).

Therefore, if your mother carried the gene for red hair and your dad did not, yet you have red hair, that would be an example of a dominant gene.

chromosome: Down syndromeDown syndrome (formerly mongolism), also known as trisomy 21, is a condition of mental retardation characterized by distinct physical characteristics. People with Down syndrome tend to have shorter life spans, aging earlier than normal. The condition is the result of an extra chromosome that is incorporated into one of the pairs the typical body has. The retardation is typically mild to moderate and such individuals are capable of education and training.

chromosome: genotype

A genotype refers to a person’s genetic makeup. This is set at birth and will never change. In the event of conflicting genes, the results can be one or the other (i.e.: dominant gene) or a blending of the two genes.

chromosome: heterozygous and homozygous

A heterozygous condition is when two matched or paired genes are different. This can cause one of the two genes to be dominant or could lead to a blending of the two genes or it could lead to the creation of recessive gene.

A homozygous condition is when two matched or paired genes are alike.

chromosome: Huntington’s disease

Huntington’s disease is a rare inherited disease affecting the central nervous system with symptoms that include progressive dementia, abnormal posture and involuntary jerking and writhing. This disease typically affects people between the age of 35 and 50. There is no cure and typically, the disease proves fatal. One who has this chromosome has a 50% change of developing the disease.

chromosome: Klinefelter syndrome

Klinefelter syndrome affects the physical and cognitive development of males.

Among the symptoms include low testosterone which leads to delayed puberty, breast development (gynecomastia), reduced body/facial hair and infertility. It can also delay/impair the dropping of the testes and reduce the size of the penis (micropenis). Disease such as breast cancer and lupus are common among affected men. Learning disabilities are also a feature of the syndrome. Klinefelter syndrome affects 1 in 500-1,000 newborn males. While the disorder begins with changes occurring within chromosomes, it is not an inherited disease.

chromosome: phenotypeA phenotype is the observable characteristic of one’s personality, originating in their genes or influenced by environmental factors.

chromosome: phenylketonuria (PKU)

Phenylketonuria (PKU) is an inherited disorder that increases phenylalanine in the blood, which can lead to cognitive impairment and other serious health issues. The substance, an amino-acid, is found naturally in proteins and artificially in sweeteners but high levels of it in the blood can lead to severe developmental problems as well as a musty odor and children tend to develop skin disorders.

chromosome: recessive geneA recessive gene is one whose influence is masked when paired genes are different (heterozygous).

chromosome: sex-linked traitsSex-linked traits refer to the consequence of a recessive gene when, in males, an X chromosome has no corresponding Y chromosome. For females, the recessive gene would have to be in both X chromosomes to show the same trait.

Such traits include color blindness and hemophilia.

chromosome: Tay-Sachs syndromeTay-Sachs syndrome is a rare inherited disorder that leads to a progressive loss of nervous function. It shows itself during infancy though for the first 3 to 6 months, the child appears normal. Babies experience seizures, vision and hearing loss, cognitive impairment and paralysis. Those with a severe form of the syndrome seldom survive early childhood.

chromosome: Turner syndrome

Turner syndrome (TS) is a chromosomal disorder where girls and woman have common traits because of a complete or partial absence of a second sex chromosome. TS occurs in 1 of every 2,000 live female births and is responsible for roughly 10% of all miscarriages. In short, the female body is not maturing the way it should.

developmental model of the brain

The brain consists of three sections:

Hindbrain – includes the medulla, pons and cerebellumMidbrain – deals with eye reflexes and movementsForebrain – made up of the limbic system, thalamus,

hypothalamus and the cerebral cortex

endocrine system and hormones

The endocrine system is a chemical communication system, whereby hormones (messages) are carried to and from the brain.

Hormones are created in the endocrine glands and are carried by blood or other bodily fluids.

endocrine: adrenal and sex glands The adrenal gland activates during times of anger or fright. Releasing epinephrine and norepinephrine into the bloodstream, the heartbeat and breathing increases. This, in turn, provides extra energy to deal with a potential problem.

Sex glands are divided into two major types – testes in males and ovaries in females. Ovaries produce eggs and the female hormone estrogen and progesterone. Testes produces sperm and the male hormone testosterone.

endocrine: hypothalamusA part of the forebrain, the hypothalamus controls hunger, thirst, sexual behavior and reactions to temperatures.

endocrine: pancreasLocated near the stomach, the pancreas is a gland that regulates sugar levels in the blood. It secretes insulin and glucagon hormones. If this is not operating properly, it can lead to diabetes (too much sugar) or hypoglycemia (not enough sugar).

endocrine: parathyroidsThe parathyroids are a part of the endocrine system, found in the neck. It produces hormones that maintain the calcium ion levels in the blood, allowing neurons to function normally.

endocrine: pineal glandThe pineal gland is a part of the endocrine system that produces melatonin. Melatonin helps regulate circadian rhythms. It is associated with seasonal affected disorder (SAD) and is also a component in sleep aids. In the U.S., such an ingredient is not regulated where in other countries, it is.

endocrine: pituitary gland

The pituitary gland (also known as the master gland) control the endocrine system and is responsible for secreting a large number of hormones. The pituitary gland is directed by the hypothalamus. The hypothalamus monitors how many hormones are being sent into the blood stream and corrects any imbalances.

Typically, the hormones interact with the organs on matters of regulating and storing nutrients. They also control growth and reproduction (ovulation and lactation in females).

endocrine: thyroid gland

The thyroid gland produces the hormone thyroxin. Not enough thyroxin and a person feels lazy or lethargic. Too much thyroxin can create hyperthyroidism which leads to weight and sleep loss as well as over-activeness.

evolutionary model of the brainThe evolutionary concept of the brain includes three sections:

Reptilian brain – is made up of the parts of the hindbrain(medulla, pons and cerebellum).

Old mammalian brain – made up of, minus the cerebral cortex, the parts of the forebrain (limbic system,thalamus and hypothalamus).

New mammalian brain – is composed of the cerebral cortex.

function tests:electroencephalogram (EEG)

An EEG refers to a machine that can record the electrical impulses of most of the brain. An EEG can monitory brain waves or rhythms.

By being able to monitor and stimulate with electrical currents certain parts of the brain, it can trick the brain in accentuating or ignoring certain signals. It has been used in the past to eliminate the pain of cancer patients as well as curbing violent tendencies.

Check out the story of Phineas Gage to discover the impact when certain parts of the brain are damaged.

function tests:positron emission tomography (PET)

A PET scan is designed to showcase the brain as its different parts are engaged in different functions. Active neurons absorb more of the radioactive solution that is injected into the blood than non-active neurons – ergo, the ability to see what part of the brain is being engaged.

function tests:functional MRI (fMRI)

A new component of MRI technology is the functional magnetic resonance imaging (fMRI) which highlights the signals the brain receives and the neural activity it engenders. However, the fMRI does not use radio frequencies to do its job as the MRI does.

geneGenes are the basic building blocks of heredity.

heritabilityHeritability refers to the genetic causes of individual traits.

lesionsLesions refer to the destruction of part of the brain. This surgical damaging of brain tissue allows for the study of the loss of function; making a connection between the loss of structure and the loss of function.

Extensive work was done on rats to figure out what part of the brain might play a role in one’s registering of appetite or fullness.

neuron and parts thereof

Neurons are long, thin cells of nerve tissue along which messages travel to and from the brain.

The neuron has three basic parts: cell body, dendrites and axon.

An axon is a long fiber that carries impulses away from the cell body towards the dendrites of the next neuron.

A cell body contains the nucleus and produces energy.

A dendrite is a short, thin fibers that stick out from the cell body.

neuron: Myelin sheathThe myelin sheath is a protective, insulating wrapping around some axons and neurons. The material comes from the glial cells.

neuron: terminal buttonsFound at the end of axons, terminal buttons are small clusters of knobs that secrete neurotransmitters that are picked up by other neurons by activating those that are nearby.

neuropsychologistsA neuropsychologist focuses on the interaction between the brain and one’s mental or cognitive processes.

neurotransmittersexcitatory and inhibitory

In order for one neuron to pass information to another neuron, it sends out chemicals called neurotransmitters. These neurotransmitters can either spur a neuron into activity (excitatory) or stop it from doing something (inhibitory).

The main types of neurotransmitters include norepinephrine, endorphin, acetylcholine and dopamine.

neurotransmitters: acetylcholine (ACh)

Acetylcholine neurotransmitters are involved with memory and movement (associated with paralysis and Alzheimer’s disease).

neurotransmitters: dopamine

Dopamine neurotransmitters are involved with learning, arousal and movement (associated with Parkinson’s disease).

neurotransmitters: endorphin

Endorphin neurotransmitters are involved with pain.

neurotransmitters: gamma-aminobutyric acid (GABA)

Gamma-aminobutyric acid is an neurotransmitter that sends messages and modulates its own function. It is an inhibitor, leading to a “calming down” of nerves.

Drugs such as valium, Ambien and Lunesta basically helps the GABA to bind itself to receptors sites. As a result, it leads to relaxation, reducing anxiety, inducing sleep and suppressing seizure activity.

neurotransmitters: glutamateGlutamate is considered the most important neurotransmitter for the brain to operate normally. It is estimated that over half of all brain synapses release this neurotransmitter.

Elevated concentrations of glutamate can lead to neural damage because of toxicity to neurons.

neurotransmitters: serotoninAn example of monoamines, serotonin plays a major role in sleeping, wakefulness as well as eating.

More recent studies have linked serotonin to aggressiveness and obsessive-compulsive behavior. Drugs such as Prozac are designed to affect serotonin circuits.

Nodes of RanvierThe Nodes of Ranvier are gaps between myelin sheath cells and are capable of generating electrical activity.

peripheral nervous system (PNS)

The PNS refer to the nerves that branch out from the spinal cord.

reflex: afferent and efferent neurons

A part of the somatic nervous system, the afferent neurons are nerve fibers (axons) that carry information inward to the central nervous system from the periphery of the body.

Also a part of the somatic nervous system, the efferent neurons are nerve fibers (axons) that carry information outward from the central nervous system to the periphery of the body.

reflex: effectorAn effector is an organ (muscle or gland) that facilitates overt behavior, either movement or secretion.

This is seen when a muscle contracts to move an arm, when a muscle squeezes saliva from salivary gland or when a gland releases a hormone into the blood.

reflex: interneuronAn interneuron is a nerve cell found completely in the central nervous system and serves as a conduit between sensory and motor neurons.

reflex: reflex arc

The reflect arc is the route followed by nerve impulses to produce a reflect act. It comes from the receptor organ through the afferent nerve to the nervous system and then through the efferent nerve to the effector organ.

reflex: sensory receptorA sensory receptor is a cell found in sense organs (tongue, eye, etc.) that initiates action potentials by traveling along sensory neurons to the central nervous system.

They are found in:Retina of the eyeCochlea of the earTaste buds of the tongueOlfactory epithelium in the nasal cavity

They are also found in:Skin TendonsMuscles Joints

saltatory conductionAction potentials have the ability to jump from node to node, across the Nodes of Ranvier. The ability to jump is referred to saltatory conduction.

This is a faster way to travel down an axon than traveling in an axon without a myelin sheath.

somatic nervous systemThe somatic nervous system (SNS) is a part of the peripheral nervous system that controls the voluntary movement of the skeletal muscles. It is also referred to as the voluntary nervous system.

It carries motor and sensory information both to and from the central nervous system.

On a completely useless but interesting aside, the term stems from the Greek word for “body” – soma.

structure tests:computerized axial tomography (CAT)

A CAT scan is a computer enhanced X-ray of the brain structure.

Doctors use CAT scans to see abnormalities in the brain structure of patients with mental disorders.

structure tests:magnetic resonance imaging (MRI)

A MRI is designed to combine the functions of a CAT and PET, using magnetic fields, radio waves and computerized enhancements to show the structure and the function of the brain.

MRI scans have a higher resolution and are more specific than CAT scans. MRI studies have shown a connection between enlarged ventricles in the brain and schizophrenic disturbance.

synapseThe synapse is the gap between the individual cell nerves.

twins: identical and fraternalIdentical twins, also known as monozygotic twins, are siblings who share all genes and heredity because they originated from the same zygote. They have been heavily researched to determine levels of influence by heredity and the environment on certain behavior.

Fraternal twins, also known as dizygotic twins, are siblings that share half of the same genes, developing from two different zygotes. Like identical twins, they are studied for many of the same reasons.

zygoteA zygote is a one-celled organism that formed by the union of a sperm and an egg. Within a zygote can be found all of the chromosomes and genes that will eventually determine the entirety of a person.

During the germinal stage during the first seven days, the zygote attaches itself to the uterine wall. However, one in five pregnancies end at this junction with the woman having no idea she was pregnant.

The development of the zygote can also determine whether a woman will have a twin or single-birth.