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7: Biological Bases: The Brain and Nervous System
The study of behavior is influenced by biology.
The techniques and research methods used to examine psychological phenomena were drawn from biology and medicine.
Different techniques are used to examine the relationship between the brain and behavior.
Researchers can correlate the structure and activity of the brain with behavior with the help of the techniques.
Brain electrical activity can be measured with an EEG, which measures subtle changes in brain electrical activity.
This data can be used by psychologists to get an electrical picture of brain activity during various cognitive states or tasks.
Cross-sectional images of the brain can be generated using a series of X-ray pictures taken from different angles.
Magnets and radio waves are used to get 3-D structural information from the brain.
These techniques only take snapshots of the brain.
Observation of the brain over time is not allowed.
Scientists can view the brain as it is working with Functional Magnetic Resonance and Positron Emission Tomography scans.
The ability to view such images by rapid sequence of magnetic resonance images is provided by Functional MR.
The images from the scans can be seen in the brain.
The main source of fuel for brain cells isglucose, and the more it is used in a given brain area, the more active it is.
The procedure allows psychologists to see what areas of the brain are working.
The central nervous system consists of the brain and the spinal cord, while the peripheral nervous system consists of all other nerves in the body.
The central processing center for thoughts, motivation, and emotions is located in the brain.
The brain and the rest of the nervous system are made up of nerve cells.
The protective bones of the spine are encased in a network of neurons.
The brain and the spine are bathed in a protective liquid.
Nerves are bundled into the cells of the spine.
Information is conveyed from the brain to and from the spine.
Nerves that send information to the brain are sensory, while those that convey information from the brain are motor.
A small subset of movements can be controlled by direct transmission from afferent to efferent cells at the level of the spine.
The responses are known as reflexes.
The path of a reflex arcs goes from sensory to motor.
A memory tip for afferent and efferent is that they are connected to the brain.
The brain and spinal cord are the only nerve cells in the body that are not in the PNS.
The PNS can be divided into two parts.
The nervous system is responsible for voluntary movement.
The heart and digestive tract are smooth muscles that are controlled by the autonomic nervous system.
These muscles aren't usually under control.
The sympathetic and parasympathetic nervous systems are part of the autonomic nervous system.
The sympathetic nervous system is associated with burning energy.
The fight-or-flight reaction is caused by an increase in heart rate and respiration and a decrease in digestion and salivation.
The parasympathetic nervous system is responsible for saving energy.
When the sympathetic system is aroused in a fight, it can cause a number of problems.
The parasympathetic system becomes active when the fight is over, sending blood to the stomach for digestion and slowing the heart rate.
The body is back to normal.
The sympathetic system sympathizes with you while you deal with the problem.
The parasympathetic system helps you descend.
The brain has three different regions that have evolved over time.
The forebrain is thelimbic system and cerebral cortex.
The cerebellum, medulla oblongata, reticular activated system, and pons are the oldest parts of the brain.
This is also called reticular formation.
The pons is a way station where neural information is passed from one brain region to another.
REM sleep is implicated by the pons.
The brain's roof and floor are the tectum and tegmentum.
The visual and auditory reflexes are governed by the tectum and tegmentum.
The emotional center of the brain is composed of the thalamus, hippocampus, amygdala, and hypothalamus.
New memories are prevented by damage to the hippocampus because they are stored in the neocortex.
The condition is known as anterograde amnesia.
Hypothalamus--controls the temperature and water balance of the body; controls hunger and sex drives; and it can be divided into Amygdala.
A lesion to the ventromedial part would cause a lot of weight gain and even death from over eating.
Give me L ess food!
The cerebral cortex is the wrinkled outer layer of the brain and is involved in higher cognitive functions such as thinking, planning, language use, and fine motor control.
The sensory cortex and motor cortex send information to this area.
The left and right cerebral hemispheres are covered by the cortex.
The two hemispheres are joined by a group of nerve fibers.
The left hemisphere is usually used for language processing and it was first noticed that brain damage to the left hemisphere in stroke patients resulted in loss of the ability to speak.
This area of the brain is called the Broca's area.
Carl Wernicke discovered an area in the left temporal lobe that can be damaged in a stroke and cause aphasia, which is the inability to comprehend speech.
The area is called Wernicke's Area.
The right hemisphere processes certain types of visual and spatial information.
The two hemispheres of the brain can operate on their own.
Experiments were performed on split-brain patients who had their callosums severed to control their epileptic seizures.
If the image is presented in the left visual field, the patients have a hard time drawing it, but if it is presented in the right visual field, they can describe it.
This is a type of processing.
The cortex is made up of association areas, which are responsible for connecting information in the sensory and motor cortices.
A variety of disorders can be caused by damage to the association areas.
The parietal, temporal, and occipital are the different parts of the cortex.
This area receives information about temperature, pressure, texture, and pain and is the home of the primary somatosensory cortexample.
The information crosses the chiasm.
Information or stimulation being passed along nerves has been the topic of much of our discussion.
Nerves are bundles of cells in the nervous system.
A nucleated cell body is known as a soma.
Branching out from the soma are dendrites, which receive input from other neurons.
The axon is a tubelike structure that responds to input from the dendrites and soma.
The axon sends a neural message and then passes it on to other cells.
The axon has a myelin sheath surrounding it.
Myelin acts as insulation for the electrical impulses carried down the axon and also speeds up the rate at which electrical information travels down the axon.
The faster the action potentials are sent, the better the insulated myelin sheath is.
The small gaps between the "beads" are known as the nodes of Ranvier, and the myelin looks like beads on a string.
Neural transmission can be sped up with the help of these nodes.
knobs on the branched end of the axon end in terminal buttons.
The terminal buttons are very close to the cell body and dendrites, but they do not touch.
There is a gap between them.
The terminal buttons release neurotransmitters, chemical messengers, across the synapse, where they bind with receptors on subsequent dendrites.
The forebrain contains the hippocampus, amygdala, and hypothalamus.
Both within and between cells are involved in neural communication.
Communication within cells is not static.
The resting membrane potential is an electric potential of 70 mV that exists in which the interior of the cell is negatively charged.
The Na + /K +ATPase and the potassium leak channels are required to establish the resting membrane potential.
The Na + /K + ATPase pumps the Na and K into the cell.
The result is a high sodium concentration outside of the cell and a high potassium concentration inside the cell.
A leak channel is a channel that is open all the time and allows the ion to leak across the membrane.
There are leak channels that allow the flow of potassium out of the cell.
The inside of the cell has a negative charge due to the loss of positive ion through Na + /K + ATPases and the leak channels.
The ratio of K + leak channels to Na + leak channels is 100:1, so the cell is virtually impermeable to sodium.
A negative charge is established along the interior of axons, along with the rest of the neuronal interior.
The cells are negative on the inside and positive on the outside.
An action potential, also referred to as a nerve impulse, is a change in the membrane potential.
It is thought of as a wave of depolarization that travels along an axon.
There is a change in the potential of the membrane from resting to positive.
The release of the neurotransmitter is caused by the movement of ions into and out of the neuron through ion channels.
The potential to normal is returned after repolarization.
"All or none" means that action potentials are either generated or not.
They are always of a fixed strength.
After a neuron fires, there is no stimulation that can cause it to fire again.
The absolute phase is followed by the relative phase, in which the neuron needs more stimulation than usual to fire again.
The neurotransmitters bind to the dendrites of the adjacent neurons.
The cell can be stimulated by excitatory neurotransmitters.
Cell firing can be stopped by neurotransmitters.
After a neurotransmitter is released, it can either be broken down by the cells or absorbed back into the cell that released it in a process called reuptake.
A helpful metaphor for the process of cell communication is thinking of neurotransmitters as keys that open the locks on the postsynaptic cell.
Various parts of our bodies communicate with one another through the endocrine system.
The system works through cells that release hormones.
Cell growth and proliferation are affected by hormones.
The master gland is the primary one.
There are many differences between hormones and neurotransmitters.
hormones are not released locally.
A wide range of responses are coordinated by hormones and neurotransmitters.
There are hormones and neurotransmitters in the bloodstream.
The body's hormones affect it for a long time.
The brain that controls the pituitary is located under the hypothalamus.
Fight-or-flight reactions are caused by stress when the pituitary releases adrenocorticotropic hormone.
The front of the neck is where the thyroid gland is located.
Evolutionary theory applies to the study of behavior.
A trait is a behavior pattern that is determined by genetics.
The basic biological elements are genes.
A dominant trait is more likely to be expressed in offspring.
A geno is the genetic makeup of a cell.
The genotype is different from the expressed features of the cell.
The observable result is the dominant one being shown in the phenotype.
When two genes are combined, the trait is shown in the phenotype.
There are rod-shaped chromosomes.
Half of our genetic makeup comes from each parent and we have 46 chromosomes.
The way in which we are different from one another is examined by the behavioral-genetics approach.
The term heritability is used to describe the degree of variation among individuals.
There are many physical and psychological characteristics.
Everything about us is not determined by genes.
Environmentality is the degree to which a trait's expression is caused by the environment in which the organisms live.
Genetics and environment have long been a concern for psychology.
The nature versus nurture debate is a controversy.
Our psychological makeup is largely the result of the interaction of the two forces of nature and nurture.
Some disorders are caused by genetic abnormality.
Down syndrome occurs when there are three copies of the 21st chromosome.
Huntington's chorea is a genetic disorder that results in muscle impairment that doesn't typically occur until after 40.
It is caused by the loss of the structure of the brain, and it is fatal.
It is passed down to the next generation because of the late start to the disease.
Scientists are trying to find ways to correct genetic flaws and provide genetic counseling because of new genetic mapping techniques.
The brain can be reorganized by severing neural connections throughout one's life.
In order to continue responding adaptably to the environment, the brain must be able to compensate for injury or disease.
Michael Gazzaniga's research focused on split-brain patients and he has also published works in cognitive neuroscience for the general reader.
Chapter 19 has answers and explanations.
Veronica's muscles seem to have lost strength and balance as she walks.
John can't seem to control his appetite no matter how hard he tries.
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