The effect on the postsynaptic membrane is less than normal when the terminal buttons are empty.
This is how the blood pressure drug reserpine works.
The terminal buttons contain dopamine.
The dopamine is destroyed by anidase inside the terminal button.
Less dopamine is released into the brain.
The distribution of neuromodulators is more widespread than the release and action of neurotransmitters.
Some neuromodulators produce their chemicals that allow the release of neurotransmitters, while others prevent the release of or general effect on the release of neurotransmitters.
Morphine is one of the best-known neuromodulators.
Kevin broke his leg playing football.
The injury was so bad that Kevin had to be hospitalized.
Mor phine blocks neural signals that transmit pain signals.
The question led researchers to look for and locatereceptors that are sensitive to chemicals like morphine.
They found out that the body's natural painkilling chemicals can be found in the receptors, so they set out to identify them.
Endorphins are produced from within.
They reduce the sensation of pain and make you feel better.
Some runners experience a "runner's high" even after a long run.
The human body has different levels of a pain killer.
We now turn our relaxation into euphoria and attention to the neural signals themselves.
To understand the signals, we must look at them at the same time in the inside and outside of the neuron.
There are two reactions that may occur.
The location of the synapse and the type of neurotransmit ter determine which reaction occurs.
Hyperpolarization can be caused by the presence of ACh at the scythes located in the skeletal muscles and at the other scythes located in other parts of the body, such as the heart.
Excitatory neurotransmitters cause the cell to allow positive ion to pass inside.
The resting potential is affected by the increase of positive ion on the inside of the neuron.
The change brings the potential closer to zero.
The neuron can reverse its elec in less than a second.
The reversal along the axon is the neural signal that opium-like chemicals are talking about.
An exchange of ion is what the action potential is all about.
The ion exchange takes place along the entire axon if the axon does not have a myelin sheath.
The ion exchange can only occur if a myelin sheath is present.
The action potential arrives at the terminal buttons more quickly because there is less work to be done.
The large myelinated axons in your legs transmit action potentials as fast as 100 meters per second (224 miles per hour), while small, un myelinated axons conduct action potentials as slowly as 1 meter per second.
The action potential is being transmitted at the same time that the neu rotransmitter is being removed.
The receiving neuron can return to a resting state if the neurotransmitter is removed.
The neuron can't fire again.
The neuron can be fired when it returns to its resting state.
The rate at which neurons fire is important.
Strong stimuli cause a high rate of firing, while weaker stimuli cause a lower rate of firing.
The low rate of firing is caused by the low pressure on your hand compared to the high pressure on your hand.
The result may be just the opposite, as not all neurons respond to the presence of a neurotransmitter by depolarizing or generating an action potential.
In these cases the neurotransmitter causes additional negative ion to cross the cell membranes and enter the neuron.
When inhibition occurs, the neuron becomes more negative than it was during the resting state, making it harder to generate.
The parasympathetic system reflects this inhibitory nature.
The result is a decrease in parasympathetic activity, such as heart rate, when ACh is released.
We are ready to move on to the bigger picture after discussing the workings of the basic units of the nervous system.
We will look at the methods neuroscientists have used to investigate the structure and function of the brain.
Some remarkable advances have been made by putting computers to work in studying the brain.
The structure and functions of the brain will be looked at.
He learned something in class about you being new to your job.
The drug can cause genetic changes.
The drug will increase the effectiveness of a neurotransmitter.
The drug will cause rapid multiplication in the body.
The brain is like a muscle, if you exercise it, it will grow larger.
The model of the acteristics could be found on the brain.
According to Joseph Gall's idea on the location of various skills and characteristics to him, bumps on the skull represented well-developed skills and personality char, which he thought could acteristics, and indentations represented less developed skills and personality character.
A list of areas in the brain that he believed were responsible for the skull was identified by Gall.
For more than 100 years, neuroscientists have been trying to locate some of these locations.
They have been trying to locate language, motor movement, and sensory impressions instead of firmness.
In just over a century, the study of the human nervous system has progressed from feeling a person's skull to collecting evidence of the brain in action.
The functions of the parts of the brain that are identified are not always told.
The clinical or case study method was used in the 19th century by a French physician.
In this method, a single patient is studied intensely.
One of the few sounds he could make was when he treated a patient nicknamed "Tan".
Tan was able to hear what was said to him because his vocal system was not paralyzed.
Tan died a few days after being treated.
Today, neuroscientists use sophisticated brain scans to answer questions that were answered by an autopsy.
The left hemisphere of Tan's brain was damaged in the autopsy.
According to the study of several other patients, this area was responsible for the ability to produce speech.
One of the most famous cases of survival from massive brain injury is that of Phineas Gage.
Gage, a 25-year-old railroad foreman, was working with explosives in Cavendish, Vermont, on September 13, 1848, trying to clear a railroad right-of-way through granite bedrock.
The procedure was straightforward.
First, drill a hole by hand, then drop an explosives charge into the hole.
If you want to protect yourself against premature explosion, pour some sand into the hole.
Gage's attention was diverted from the task at hand when he dropped the iron onto the rock.
A rocket that shot through the left side of Gage's face and exited through his head was caused by the drilled hole that served as a launching pad.
Gage was not killed in the accident, but there were many problems after the accident.
Gage was an excellent worker who got along well with others and carried through with his plans after the accident.
He used gross profanity, refused to listen if what others said interfered with what he wanted, and was very angry after the accident.
Information about brain functioning is provided by the study of people who have suffered brain damage.
Phineas Gage had the most common form of brain damage in adults.
The mon cause was missed by the tamping rod.
The behavior, thought processes, and brain of a person are crucial to survival.
The size of the chologists with specialized training in the diagnosis and treatment of dis iron bar that passed through his head can learn a lot about specific functions on the left.
The 150th anniversary of the terrible accident that struck Phineas Gage was celebrated in 1998.
The measures to assess people who have suffered brain damage are shown in this figure.
Gage had a model of what he looked like.
The measures help identify the specific form of brain damage and are useful in the rehabilitation of brain damage.
The patient pictured here has suffered a stroke, and his language abilities are being assessed in order to help him communicate better.
After wars in which a large number of injuries occurred, there have been major advances in the study of the brain's electrical activity.
Increased attempts to brain waves alter those structures when abnormal behaviors are noticed is a result of advances in locating form of a graphic representation of key parts of the brain.
A majority of former National Football League players have had at least one concussion.
The risks are too high for coaches to tell players to walk it off and get back in the game.
A concussion is a type of traumatic brain injury that can change the way the brain works, according to the Centers for Disease Control.
The symptoms of concussion include headaches, nausea or vomiting, balance problems, dizziness, double or blurry vision, difficulty paying attention, and memory problems.
The stereotaxic is studying certain brain structures.
Before the inven instrument allowed researchers to examine structures that were deep in the brain, they had to remove or damage the tissue that covered them.
A fine piece of specially treated wire can be inserted into a patient's brain if the head is in a fixed position.
The electrode is thin enough that it doesn't damage the tissue as it passes through the brain.
The electrical brain can be recorded.
This activity stimulates brain activity with a mild electric current or destroys a brain area by using a strong electric current through it.
Information about the func obsessive-compulsive disorder is provided by the symptoms of disorders such as procedures.
The stereotaxic instrument can be used to inject chemicals into the brain.
These chemicals can be used to destroy brain areas.
Stereotaxic instruments have been used on a variety of animals and humans.
The risk that the operation will cause permanent changes in the patient's abilities or personality raises ethical questions.
Stereotaxic surgery is a last resort for this reason.
Neurosciences have been able to examine brain functions without resorting to surgery.
The signals from the brain activity transmitted to the EEG system are amplified by the electrodes.
The eeG participant is shown with a number of different types of brain waves.
The presence of a small electrode in the brain tells us something about what is happening in the brain waves generated by millions of people.
The alpha waves will disappear if you close your eyes and pay attention to your surroundings.
If there is damage to the brain, the waves may be absent or reduced.
Delta waves are common in infants up to 1 year of age and in the deep est stages of sleep.
The different states of consciousness associated with brain waves will be discussed in Chapter 5.
The possible presence of brain tumors can be seen in the brain's Chapter 5 discussion of narcolepsy.
Despite these uses, the EEG has limited useful observed types of brain waves because it is not precise enough to monitor local activity.
More detailed technol ogy has been developed because of the general nature of the EEG.
The method is more precise and easier to use than the traditional procedure.
Major advances have been made in the study of the brain with the advent of computers.
A computer uses measures of brain activity to create a brain image.
The way an X-ray provides an image of a bone is similar to the way a brain nique provides static or single-point-in-time pictures of brain structures.
The static images are provided by the machines.
The most recent brain scanning techniques provide ongoing or dynamic images of the brain.
A computer combines the X-rays taken from different angles to produce X-rays that are interpreted by a computer multiple brain images.
The use of radio waves and a strong magnetic field causes the spin of the waves to cause hydrogen atoms to emit a signal.
The thicker the tissue, the stronger the signal that can be interpreted by a number of hydrogen atoms.
The introduction of the cT or caT scan on the left was a dramatic improvement over X-rays.
The ability to see brain injuries and malfunction that were not visible using earlier techniques has led to major advances in research.
If you compare Figures 2-13A and 2-13B, you will see that the details produced by the scans are better than those of the computed toms.
The patient is injected with radioactive blood sugar.
The most active areas of the brain are the ones with larger amounts of fuel.
The radioactivity of various brain areas can be monitored with the help of PET.
The selection of the colors used to show brain activity is arbitrary.
They use yellow and red to show high activity, green to show average activity, and blue to show below average activity.
Depending on whether we are resting, listening to language, or listening to music, there are different levels of brain activity.
The patient needs to be con scious and able to process the stimuli that are presented in order for the scans to be useful.
The relation between the ner vous system and various mental processes has been studied by neuroscientists.
The role of various brain structures in a range of behaviors has been determined using fMRI.
The more efficient word processing regions of the brain are used more by dyslexics.
College students use different parts of the brain to answer certain types of questions, according to research using fMRI scans.
When the gantyne is about to be positioned.
Photographs of PeT scans taken while a person is resting and listening to music and language together and separately.
A high level of brain activity is shown by the red and yellow color of the scans, while a low level of activity is shown by the green and blue color.
These techniques are being used to investigate the biological components of psychological disorders.
A few years ago, this type of research wouldn't have been possible.
A construction worker may have suffered brain damage from a head injury.
You can choose from a MEG, a EEG, aCT Scan, and a PET Scan.
Write down the procedure you would recommend.
When quick evaluations are needed, magnetic resonance is not used.
The results of the brain scans are not sufficiently precise because they are not designed to detect damaged tissue.
Accident victims need quicker scans.
In this section we discuss the various methods neuroscientists use to study the brain, and now we look at what those meth ods have revealed about the structures and functioning of the brain.
Before we discuss some of the more complicated processes controlled by the brain, let's review some behaviors that don't reach the brain.
Some of your behavior is caused by reflexes like knee jerks and attempts to pull your hand out of a car door.
The time saved by restricting these behaviors to the spine had survival value, and thus they have been passed on.
We live in a changing environment that requires more than reflexes.
The information is sent up the spine to the brain.
Let's take a closer look.
The medulla, pons, and cerebellum are part of the hindbrain.
The oldest parts of the brain have important survival functions.
If our respiratory center is damaged, we can't breathe automatically because we have to think about the other parts of the brain.
Your breathing may increase when the hand-stuck-under-the-seat information reaches the medulla.
The cerebellum and blood circulation are involved in movement.
The description fails to explain how the cerebellum works in conjunction with other brain areas that initiate motor move for sleep and arousal, which we will discuss later.
Police officers use a variety of tests to determine if a driver is under the influence of alcohol.
The driver's performance on such tests is likely to be affected by the effects of alcohol on the cerebellum.
It can be affected by even small amounts of alcohol.
Drivers suspected of driving under the influence of alcohol are often asked to complete a series of tests to see if their motor coordination has been affected by alcohol.
Patients with neurodegenerative diseases that shrink the cerebellum are less accurate in judging fine differences between the pitch of two tones.
People with damage to the cerebellum are more prone to make errors when trying to detect moving objects.
These findings are not what one would expect from a brain region focused on motor coordination.
Patients can recover from injuries to the cerebellum.
Time and mal function can be regained with the removal of the cerebellum.
There is a general and subtle support function in sensory, cognitive, and affective processes that goes well beyond motor movement alone.
The reticular formation goes all the way from the hindbrain to the forebrain.
You probably didn't sleep very well when you first moved in.
You can sleep through everything now that you are used to your new environment.
The reticular forma at the top of the spine was involved in the change.
The sound of Nerve fibers passing through the refrigerator motor or air conditioner is blocked by the reticular formation in the brain, which makes it impossible for us to notice it.
The amygdala is involved in emotional reactivity.
The hippocampus is involved in emotional reactivity.
Refer to Figure 2-15 so that you know the location of each structure, and take some time to learn about them.
The neural fibers that connect the two hemispheres are also connected to other parts of the brain that play a role in motor move of the brain.
Parkinson's disease is caused by the loss of dopamine in the brain.
The convoluted outer layer structures that are involved in the regulation of emotions and motivated behaviors such as hunger, thirst, aggression, and sexual behavior can be seen in Table 2-2.
There is a large number of nerve fibers that travel from the thalamus to the cerebral cortex.
You might be wondering how sensory information gets to the correct location for further processing.
The cerebral cortex and other parts of the spine are brought to you by nerve tracts.
The brain goes to an appropriate area when it reaches the thalamus.
The sense of smell is processed in the olfactory bulb.
The limbic system has connections to other parts of the brain.
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Despite its small size, this structure deep inside the brain plays a role in fighting and fleeing.
A key role in memory is the large subcortical structure.
You may not remember if you were hit in the head on the football field or in a car accident.
You won't remember the hit to your head on the football field if consolidation doesn't happen.
The human cortex has a wrinkled and wrinkled appearance that resembles a walnuts or cauliflower.
The cerebral cortexample was stuffed in crumpling because the brain was confined within the skull.
A rat's cortex is the size of a postage stamp.
A monkey's cortex is the size of an envelope.
There are some specialized responsibilities for each of the lobes.
Here is a closer look at them.
They are easy to spot because they are large, accounting for half of the volume of the cerebral hemispheres.
Motor functions that are most important to our survival are more likely to be voted to the cortical area.
Large motor areas are devoted to manual dexterity because the use of our hands is so important to survival.
Chapter 3 has connections to the limbic system of the brain.
The largest part of the cortex was devoted to the fingers.
One consequence of this syndrome is that patients may neglect an entire side of their body and fail to engage in typical behaviors such as grooming.
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The information needed to create these maps was provided by the electrical parts of the brain.
Patients don't experience pain from the electrical stimulation because the brain doesn't have a pain receptors.
A person will move his or her left hand if an electrode is placed near the top of his or her brain.
The whole series of motor movements and brain areas responsible for such movements will be revealed if you keep moving that elec trode just a bit.
The brain map shows that most areas of the brain don't give rise to a motor or sensory response.
These areas are similar to highways in that they move memories, thoughts, and impressions, connecting them with other elements such as emotions and future plans.
A large part of the brain works in the grand saga of making associations among events, ideas, personal expe riences, strategies and people.
Many people think that only 10% of the brain is used.
This doesn't mean that these are unused areas.
The results of brain scans show that large areas of the brain are used for various cognitive tasks, and these areas are often different depending on the task at hand.
Don't be fooled by the idea that your brain isn't being used, you should give a task your best effort.
Learning, memory, and emotions are all affected by these lobes.
Damage to the temporal lobes can affect our ability to learn.
Attacks of anger and rage have been linked to seizures in the temporal lobes.
The temporal lobes' connections to the hippocampus and amygdala are important in learning, memory, and emotion.
The occipital lobes are supposed to process visual information.
We process and understand visual information through highly specialized neurons, even though we don't see it through the eyes.
Some neurons are acti vated by vertical lines, others by horizontal lines, and still others by lines of a cer tain length.
Some neurons only respond to certain colors or shapes.
The first line of neurons process simple visual information such as contrast and car ries this information to a second layer of neurons that processes shapes and then on to additional layers of neurons for complete processing of the incoming visual input.
Half of the visual field is sent to the occipital lobes.
Information from the right visual field is sent to the left occipital lobe.
There are many con nections between the two occipital lobes, so visual information is processed holistically unless there is some type of damage.
The result is blindness in the opposite visual field if only one occipital lobe is damaged.
Consider the case of Dr. P., a music teacher with visual problems.
He took parking meters for children.
The problem was caused by a tumor in the visual area of his brain.
The existence of a complex and continually developing language is one of the key differences between humans and lower animals.
As a result, neuroscientists have focused on the brain structures responsible for language as well as the problems that develop when these areas are dam aged.
In the majority of the population, the left hemisphere dominates for language and speech.
Damage to either or both areas can affect a person's hearing and language abilities.
The brain that is responsible for understanding what others say to them is located at the back of the people's lobes.
In contrast to the speech of people understanding or producing spoken words, damage to Wernicke's area results in meaningless speech.
Damage to the right hemisphere is involved in apraxias.
People can't display emotions.
The two hemispheres of the cerebral cortex are connected by the corpus callosum, which is about the size of a small banana.
The psychologists wondered what would happen if the communication between the two hemispheres was cut.