Chapter 5

Acetylcholine

involved in: muscle action, memory Potential effect on Behavior: Increased arousal, enhanced cognition

Beta-endorphin

involved in: pain, pleasure Potential effect on behavior: decreased anxiety, decreased tension

Gyri

(plural: gyri) bump or ridge on the cerebral cortex

sulci

(plural: sulci) depressions or grooves in the cerebral cortex

severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling the spread of seizures (Figure 10). While this is an effective treatment option, it results in individuals who have split brains. After surgery, these split-brain patients show a variety of interesting behaviors. For instance, a split-brain patient is unable to name a picture that is shown in the patient's left visual field because the information is only available in the largely nonverbal right hemisphere. However, they are able to recreate the picture with their left hand, which is also controlled by the right hemisphere. When the more verbal left hemisphere sees the picture that the hand drew, the patient is able to name it (assuming the left hemisphere can interpret what was drawn by the left hand).

As you learned earlier, the right hemisphere controls the left side of the body; also, the brain's main motor centers are located at the front of the head, in the frontal lobe. frontal lobe—the prefrontal cortex, which is associated with judgment, reasoning, and impulse control.

Categories of the brain

Forebrain Midbrain Hindbrain

Behavioral genetics studies examine how genes and environment interact

Frequently use twin and adoption study methods • Range of reaction • Gene-environment correlation • Epigenetics

two cell types that make up the nervous system

Glia and neurons glia generally plays supporting roles

reuptake inhibitors

In contrast to agonists and antagonists, which both operate by binding to receptor sites, reuptake inhibitors prevent unused neurotransmitters from being transported back to the neuron. This leaves more neurotransmitters in the synapse for a longer time, increasing its effects.

functional magnetic resonance imaging (fMRI)

MRI that shows changes in metabolic activity over time shows changes in brain activity over time by tracking blood flow and oxygen levels. The fMRI provides more detailed images of the brain's structure, as well as better accuracy in time, than is possible in PET scans (Figure 23). With their high level of detail, MRI and fMRI are often used to compare the brains of healthy individuals to the brains of individuals diagnosed with psychological disorders.

Depolarization

Membrane potential becomes less negative •Excitation

Gene

Sequence of DNA that controls or partially controls physical characteristics known as traits (eye color, hair color etc).

Phineas Gage and the Tamping Rod

Symptoms included changes in personality, such as: ü acting agitated and disrespectful ü gross profanity ü poor self-control ü giving in to "animal" desires ü decreased social abilities

How neurons communicate

The neuron exists in a fluid environment—it is surrounded by extracellular fluid and contains intracellular fluid (i.e., cytoplasm). The neuronal membrane keeps these two fluids separate—a critical role because the electrical signal that passes through the neuron depends on the intra- and extracellular fluids being electrically different. This difference in charge across the membrane, called the membrane potential, provides energy for the signal. The electrical charge of the fluids is caused by charged molecules (ions) dissolved in the fluid. Between signals, the neuron membrane's potential is held in a state of readiness, called the resting potential. Like a rubber band stretched out and waiting to spring into action, ions line up on either side of the cell membrane, ready to rush across the membrane when the neuron goes active and the membrane opens its gates (i.e., a sodium-potassium pump that allows movement of ions across the membrane). Ions in high-concentration areas are ready to move to low-concentration areas, and positive ions are ready to move to areas with a negative charge. In the resting state, sodium (Na+) is at higher concentrations outside the cell, so it will tend to move into the cell. Potassium (K+), on the other hand, is more concentrated inside the cell, and will tend to move out of the cell (Figure 4). In addition, the inside of the cell is slightly negatively charged compared to the outside. This provides an additional force on sodium, causing it to move into the cell. From this resting potential state, the neuron receives a signal and its state changes abruptly (Figure 5). When a neuron receives signals at the dendrites—due to neurotransmitters from an adjacent neuron binding to its receptors—small pores, or gates, open on the neuronal membrane, allowing Na+ ions, propelled by both charge and concentration differences, to move into the cell. With this influx of positive ions, the internal charge of the cell becomes more positive. If that charge reaches a certain level, called the threshold of excitation, the neuron becomes active and the action potential begins. This process of when the cell's charge becomes positive, or less negative, is called depolarization. Many additional pores open, causing a massive influx of Na+ ions and a huge positive spike in the membrane potential, the peak action potential. At the peak of the spike, the sodium gates close and the potassium gates open. As positively charged potassium ions leave, the cell quickly begins repolarization. At first, it hyperpolarizes, becoming slightly more negative than the resting potential, and then it levels off, returning to the resting potential. This positive spike constitutes the action potential: the electrical signal that typically moves from the cell body down the axon to the axon terminals. The electrical signal moves down the axon like a wave; at each point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions. The action potential moves all the way down the axon to the terminal buttons. The action potential is an all-or-none phenomenon. In simple terms, this means that an incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation. There is no in-between, and there is no turning off an action potential once it starts. Think of it like sending an email or a text message. You can think about sending it all you want, but the message is not sent until you hit the send button. Furthermore, once you send the message, there is no stopping it. Because it is all or none, the action potentialis recreated, or propagated, at its full strength at every point along the axon. Much like the lit fuse of a firecracker, it does not fade away as it travels down the axon. It is this all-or-none property that explains the fact that your brain perceives an injury to a distant body part like your toe as equally painful as one to your nose. As noted earlier, when the action potential arrives at the terminal button, the synaptic vesicles release their neurotransmitters into the synapse The neurotransmitters travel across the synapse and bind to receptors on the dendrites of the adjacent neuron, and the process repeats itself in the new neuron (assuming the signal is sufficiently strong to trigger an action potential). Once the signal is delivered, excess neurotransmitters in the synapse drift away, are broken down into inactive fragments, or are reabsorbed in a process known as reuptake. Reuptake involves the neurotransmitter being pumped back into the neuron that released it, in order to clear the synapse (Figure 6). Clearing the synapse serves both to provide a clear "on" and "off" state between signals and to regulate the production of neurotransmitter (full synaptic vesicles provide signals that no additional neurotransmitters need to be produced).

Hippocampus

structure in the temporal lobe associated with learning and memory is an essential structure for learning and memory.

primary motor cortex

This strip running along the side of the brain is in charge of voluntary movements like waving goodbye, wiggling your eyebrows, and kissing. It is an excellent example of the way that the various regions of the brain are highly specialized. Interestingly, each of our various body parts has a unique portion of the primary motor cortex devoted to it.

fight or flight response

activation of the sympathetic division of the autonomic nervous system, allowing access to energy reserves and heightened sensory capacity so that we might fight off a given threat or run away to safety

Psychoactive drugs can act as

agonists or antagonists Agonist and antagonist drugs are prescribed to correct the specific neurotransmitter imbalances underlying a person's condition. (Parkinson's disease, a progressive nervous system disorder, is associated with low levels of dopamine. Therefore dopamine agonists, which mimic the effects of dopamine by binding to dopamine receptors, are one treatment strategy.)

Drugs can act either

agonists or as antagonists for a given neurotransmitter system.

action potential is an

all or none phenomenon=phenomenon that incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation Because it is all or none, the action potentialis recreated, or propagated, at its full strength at every point along the axon.

prefrontal cortex

area in the frontal lobe responsible for higher-level cognitive functioning which is responsible for higher-level cognitive functioning

range of reaction

asserts that our genes set the boundaries within which we can operate, and our environment interacts with the genes to determine where in that range we will fall. For example, if an individual's genetic makeup predisposes her to high levels of intellectual potential and she is reared in a rich, stimulating environment, then she will be more likely to achieve her full potential than if she were raised under conditions of significant deprivation. According to the concept of range of reaction, genes set definite limits on potential, and environment determines how much of that potential is achieved.

parasympathetic nervous system

associated with routine, day-to-day operations of the body activation is associated with normal functioning under relaxed conditions. associated with returning the body to routine, day-to-day operations. Once the threat has been resolved, the parasympathetic nervous system takes over and returns bodily functions to a relaxed state. Our hunter's heart rate and blood pressure return to normal, his pupils constrict, he regains control of his bladder, and the liver begins to store glucose in the form of glycogen for future use. These processes are associated with activation of the parasympathetic nervous system.

terminal buttons

axon terminal containing synaptic vesicles

autonomic nervous system

controls our internal organs and glands controls the function of our organs and glands, and can be divided into the sympathetic and parasympathetic divisions. controls our internal organs and glands and is generally considered to be outside the realm of voluntary control. It can be further subdivided into the sympathetic and parasympathetic divisions= The two systems have complementary functions, operating in tandem to maintain the body's homeostasis.

Psychologists who take a biological perspectiveand focus on the physiological causes of behavior assert that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems. In this perspective, psychotropic medications can help improve the symptoms associated with these disorders. Psychotropic medications are drugs that treat psychiatric symptoms by restoring neurotransmitter balance.

biological perspective= view that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems psychotropic medications=drugs that treat psychiatric symptoms by restoring neurotransmitter balance

Central Nervous System (CNS)

brain and spinal cord

The medulla, pons, and midbrain together are known as

brainstem.

dendrites

branch-like extension of the soma that receives incoming signals from other neurons

Damage to either Broca's area or Wernicke's area

can result in language deficits

neurons

cells in the nervous system that act as interconnected information processors, which are essential for all of the tasks of the nervous system on the other hand, serve as interconnected information processors that are essential for all of the tasks of the nervous system. This section briefly describes the structure and function of neurons. central building blocks of the nervous system, The neuron is a small information processor, and dendrites serve as input sites where signals are received from other neurons. These signals are transmitted electrically across the soma and down a major extension from the soma known as the axon, which ends at multipleterminal buttons. The terminal buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous system. In healthy individuals, the neuronal signal moves rapidly down the axon to the terminal buttons, where synaptic vesicles release neurotransmitters into the synapse.

neurtotransmitters

chemical messenger of the nervous system

Neurotransmitters

chemical messenger of the nervous system There are several different types of neurotransmitters released by different neurons,

brain

comprised of billions of interconnected neurons and glia. It is a bilateral, or two-sided, structure that can be separated into distinct lobes. Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors.

lateralization

concept that each hemisphere of the brain is associated with specialized functions There is evidence of some specialization of function—referred to as lateralization—in each hemisphere, mainly regarding differences in language ability.

Peripheral Nervous System (PNS)

connects the brain and spinal cord to the muscles, organs and senses in the periphery of the body is comprised of the somatic and autonomic nervous systems. PNS connects the CNS to the rest of the body. made up of thick bundles of axons, called nerves, carrying messages back and forth between the CNS and the muscles, organs, and senses in the periphery of the body (i.e., everything outside the CNS). The PNS has two major subdivisions: the somatic nervous system and the autonomic nervous system.

longitudinal fissure

deep groove in the brain's cortex The most prominent sulcus, known as the longitudinal fissure, is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.

membrane potential

difference in charge across the neuronal membrane This difference in charge across the membrane, called the membrane potential, provides energy for the signal.

hindbrain

division of the brain containing the medulla, pons, and cerebellum is located at the back of the head and looks like an extension of the spinal cord. It contains the medulla, pons, and cerebellum medulla and pons cerebellum

midbrain

division of the brain located between the forebrain and the hindbrain; contains the reticular formation comprised of structures located deep within the brain, between the forebrain and the hindbrain. The reticular formation is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity. The substantia nigra(Latin for "black substance") and the ventral tegmental area (VTA) are also located in the midbrain= Both regions contain cell bodies that produce the neurotransmitter dopamine, and both are critical for movement. Degeneration of the substantia nigra and VTA is involved in Parkinson's disease. In addition, these structures are involved in mood, reward, and addiction

antagonist

drug that blocks or impedes the normal activity of a given neurotransmitter blocks or impedes the normal activity of a neurotransmitter at the receptor.

Antagonist

drug that blocks or impedes the normal activity of a given neurotransmitter.

agonists

drug that mimics or strengthens the effects of a neurotransmitter are chemicals that mimic a neurotransmitter at the receptor site and, thus, strengthen its effects.

agonist

drug that mimics or strengthens the effects of a neurotransmitter.

action potential

electrical signal that moves down the neuron's axon This positive spike constitutes the action potential: the electrical signal that typically moves from the cell body down the axon to the axon terminals. The electrical signal moves down the axon like a wave; at each point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions.The action potential moves all the way down the axon to the terminal buttons.

Neuronal communication

electrochemical event. The dendrites contain receptors for neurotransmitters released by nearby neurons. If the signals received from other neurons are sufficiently strong, an action potential will travel down the length of the axon to the terminal buttons, resulting in the release of neurotransmitters into the synapse.

Neuronal communication is often referred to as an

electrochemical event. The movement of the action potential down the length of the axon is an electrical event, and movement of the neurotransmitter across the synaptic space represents the chemical portion of the process.

somatosensory cortex

essential for processing sensory information from across the body, such as touch, temperature, and pain The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex.

myelin sheath

fatty substance that insulates axons coats the axon and acts as an insulator, increasing the speed at which the signal travels. The myelin sheath is crucial for the normal operation of the neurons within the nervous system: the loss of the insulation it provides can be detrimental to normal function. (Multiple sclerosis (MS), an autoimmune disorder, involves a large-scale loss of the myelin sheath on axons throughout the nervous system. The resulting interference in the electrical signal prevents the quick transmittal of information by neurons and can lead to a number of symptoms, such as dizziness, fatigue, loss of motor control, and sexual dysfunction.)

Hypothalamus

forebrain structure that regulates sexual motivation and behavior and a number of homeostatic processes; serves as an interface between the nervous system and the endocrine system regulates a number of homeostatic processes, including the regulation of body temperature, appetite, and blood pressure. The hypothalamus also serves as an interface between the nervous system and the endocrine system and in the regulation of sexual motivation and behavior.

The cerebral cortex has four lobes

frontal, parietal, occipital, temporal

four lobes of the brain

frontal, parietal, temporal, and occipital lobes

psychological disorders involve imbalances in

given neurotransmitter system. psychotropic drugs are prescribed in an attempt to bring the neurotransmitters back into balance.

The nervous system is composed of two basic cell types:

glial cells (also known as glia) and neurons.

soma

has branching extensions known as dendrites.

pons

hindbrain structure that connects the brain and spinal cord; involved in regulating brain activity during sleep literally means "bridge," and as the name suggests, the pons serves to connect the brain and spinal cord. It also is involved in regulating brain activity during sleep.

medulla

hindbrain structure that controls automated processes like breathing, blood pressure, and heart rate controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate

Cerebellum

hindbrain structure that controls our balance, coordination, movement, and motor skills, and it is thought to be important in processing some types of memory receives messages from muscles, tendons, joints, and structures in our ear to control balance, coordination, movement, and motor skills. The cerebellum is also thought to be an important area for processing some types of memories. In particular, procedural memory, or memory involved in learning and remembering how to perform tasks, is thought to be associated with the cerebellum. Recall that H. M. was unable to form new explicit memories, but he could learn new tasks. This is likely due to the fact that H. M.'s cerebellum remained intact.

Computerized Tomography (CT)

imaging technique in which a computer coordinates and integrates multiple x-rays of a given area involves taking a number of x-rays of a particular section of a person's body or brain The x-rays pass through tissues of different densities at different rates, allowing a computer to construct an overall image of the area of the body being scanned. A CT scan is often used to determine whether someone has a tumor, or significant brain atrophy.

Wernicke's area

important for speech comprehension important for speech comprehension, is also located here. Whereas individuals with damage to Broca's area have difficulty producing language, those with damage to Wernicke's area can produce sensible language, but they are unable to understand it.

limbic system

involved in emotional responses and memory

sympathetic

involved in stress-related activities and functions activation prepares us for fight or flight, involved in preparing the body for stress-related activities The sympathetic nervous system is activated when we are faced with stressful or high-arousal situations. his body undergoes a series of changes—a direct function of sympathetic activation—preparing him to face the threat. His pupils dilate, his heart rate and blood pressure increase, his bladder relaxes, his liver releases glucose, and adrenaline surges into his bloodstream. This constellation of physiological changes, known as the fight or flight response, allows the body access to energy reserves and heightened sensory capacity so that it might fight off a threat or run away to safety.

Norepinephrine

involved in: Heart, intestines, alertness. Potential effect on Behavior: Increased arousal, suppressed appetite

Serotonin

involved in: Mood, sleep Potential effect on Behavior: modulated mood, suppressed appetite

Gamma-aminobutyric acid (GABA)

involved in: brain function, sleep Potential effect on Behavior: Decreased anxiety, decreased tension

Glutamate

involved in: memory, learning Potential effect on Behavior: increased learning, enhanced memory

Dopamine

involved in: mood, sleep, learning Potential effect on Behavior: increased pleasure, suppressed appetite

Positron Emission Tomography (PET)

involves injecting individuals with a mildly radioactive substance and monitoring changes in blood flow to different regions of the brain scans create pictures of the living, active brain An individual receiving a PET scan drinks or is injected with a mildly radioactive substance, called a tracer. Once in the bloodstream, the amount of tracer in any given region of the brain can be monitored. As brain areas become more active, more blood flows to that area. A computer monitors the movement of the tracer and creates a rough map of active and inactive areas of the brain during a given behavior. PET scans show little detail, are unable to pinpoint events precisely in time, and require that the brain be exposed to radiation; therefore, this technique has been replaced by the fMRI as an alternative diagnostic tool. However, combined with CT, PET technology is still being used in certain contexts. For example, CT/PET scans allow better imaging of the activity of neurotransmitter receptors and open new avenues in schizophrenia research. In this hybrid CT/PET technology, CT contributes clear images of brain structures, while PET shows the brain's activity.

limbic system

is involved in processing both emotion and memory. Interestingly, the sense of smell projects directly to the limbic system; therefore, not surprisingly, smell can evoke emotional responses in ways that other sensory modalities cannot. The limbic system is made up of a number of different structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus

forebrain

largest part of the brain, containing the cerebral cortex, the thalamus, and the limbic system, among other structures Other areas of the forebrain (which includes the lobes that you learned about previously), are the parts located beneath the cerebral cortex, including the thalamus and the limbic system.

forebrain

largest part of the brain, containing the cerebral cortex, the thalamus, and the limbic system, among other structures The two hemispheres of the cerebral cortex are part of the forebrain (Figure 11), which is the largest part of the brain. forebrain contains the cerebral cortex and a number of other structures that lie beneath the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system (collection of structures).

left hemisphere

left hemisphere controls the right half of the body

threshold of excitation

level of charge in the membrane that causes the neuron to become active If that charge reaches a certain level, called the threshold of excitation, the neuron becomes active and the action potential begins

Neuronal communication is made possible by the neuron's specialized structures

like the soma, dendrites, axons, terminal buttons, and synaptic vesicles.

nucleus of the neuron

located in the soma, or cell body.

magnetic resonance imaging (MRI)

magnetic fields used to produce a picture of the tissue being imaged a person is placed inside a machine that generates a strong magnetic field. The magnetic field causes the hydrogen atoms in the body's cells to move. When the magnetic field is turned off, the hydrogen atoms emit electromagnetic signals as they return to their original positions. Tissues of different densities give off different signals, which a computer interprets and displays on a monitor.

axon

major extension of the soma Axons range in length from a fraction of an inch to several feet. In some axons, glial cells form a fatty substance known as the myelin sheath, which coats the axon and acts as an insulator, increasing the speed at which the signal travels.

reticular formation

midbrain structure important in regulating the sleep/wake cycle, arousal, alertness, and motor activity is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity.

ventral tegmental area (VTA)

midbrain structure where dopamine is produced: associated with mood, reward, and addiction

substantia nigra

midbrain structure where dopamine is produced; involved in control of movement

glial cells

nervous system cell that provides physical and metabolic support to neurons, including neuronal insulation and communication, and nutrient and waste transport which outnumber neurons ten to one, are traditionally thought to play a supportive role to neurons, both physically and metabolically. Glial cells provide scaffolding on which the nervous system is built, help neurons line up closely with each other to allow neuronal communication, provide insulation to neurons, transport nutrients and waste products, and mediate immune responses.

hyperpolarize

neuron becoming slightly more negative than the resting potential it hyperpolarizes, becoming slightly more negative than the resting potential, and then it levels off, returning to the resting potential.

reuptake

neurotransmitter is pumped back into the neuron that released it involves the neurotransmitter being pumped back into the neuron that released it, in order to clear the synapse (Figure 6). Clearing the synapse serves both to provide a clear "on" and "off" state between signals and to regulate the production of neurotransmitter (full synaptic vesicles provide signals that no additional neurotransmitters need to be produced).

temporal lobe

part of cerebral cortex associated with hearing, memory, emotion, and some aspects of language; contains primary auditory cortex is located on the side of the head (temporal means "near the temples"), and is associated with hearing, memory, emotion, and some aspects of language. auditory cortex, the main area responsible for processing auditory information, is located within the temporal lobe. Wernicke's area, important for speech comprehension, is also located here.

occipital lobe

part of the cerebral cortex associated with visual processing; contains the primary visual cortex is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information. The occipital cortex is organized retinotopically, which means there is a close relationship between the position of an object in a person's visual field and the position of that object's representation on the cortex.

parietal lobe

part of the cerebral cortex involved in processing various sensory and perceptual information; contains the primary somatosensory cortex is located immediately behind the frontal lobe, and is involved in processing information from the body's senses. It contains the somatosensory cortex, which is essential for processing sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex.

frontal lobe

part of the cerebral cortex involved in reasoning, motor control, emotion, and language; contains motor cortex (Phineas Gage) One particularly fascinating area in the frontal lobe is called the "primary motor cortex". is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for higher-level cognitive functioning; and Broca's area, which is essential for language production.

depolarization

process of when the cell's charge becomes positive, or less negative

receptors

protein on the cell surface where neurotransmitters attach proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes "matching" different neurotransmitters. small pores, or gates, open on the neuronal membrane, allowing Na+ ions, propelled by both charge and concentration differences, to move into the cell. With this influx of positive ions, the internal charge of the cell becomes more positive.

Electroencephalogram (EEG)

recording the electrical activity of the brain via electrodes on the scalp serves this purpose by providing a measure of a brain's electrical activity. An array of electrodes is placed around a person's head The signals received by the electrodes result in a printout of the electrical activity of his or her brain, or brainwaves, showing both the frequency (number of waves per second) and amplitude (height) of the recorded brainwaves, with an accuracy within milliseconds. Such information is especially helpful to researchers studying sleep patterns among individuals with sleep disorders.

Broca's area

region in the left hemisphere that is essential for language production which is essential for language production. People who suffer damage to Broca's area have great difficulty producing language of any form.

The hindbrain contains structures necessary to

regulate breathing and respiration

thalamus

relay center of the brain sensory relay for the brain is a sensory relay for the brain. All of our senses, with the exception of smell, are routed through the thalamus before being directed to other areas of the brain for processing

somatic nervous system

relays sensory and motor information to and from the CNS transmits sensory and motor signals to and from the central nervous system. associated with activities traditionally thought of as conscious or voluntary. It is involved in the relay of sensory and motor information to and from the CNS; therefore, it consists of motor neurons and sensory neurons. Motor neurons, carrying instructions from the CNS to the muscles, are efferent fibers (efferent means "moving away from"). Sensory neurons, carrying sensory information to the CNS, are afferent fibers (afferent means "moving toward"). Each nerve is basically a two-way superhighway, containing thousands of axons, both efferent and afferent.

Regions of the midbrain are related to

reward and movement

right hemisphere

right hemisphere controls the left half of the body.

genes

sequence of DNA that controls or partially controls physical characteristics

synapse

small gap between two neurons where communication occurs is a very small space between two neurons and is an important site where communication between neurons occurs. Once neurotransmitters are released into the synapse, they travel across the small space and bind with corresponding receptors on the dendrite of an adjacent neuron.

spinal cord

spinal cord is what connects the brain to the outside world. relay station routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes. top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such as breathing and digestion. spinal cord ends just below the ribs Sensory nerves bring messages in; motor nerves send messages out to the muscles and organs. Messages travel to and from the brain through every segment. Some sensory messages are immediately acted on by the spinal cord, without any input from the brain. Withdrawal from heat and knee jerk are two examples. When a sensory message meets certain parameters, the spinal cord initiates an automatic reflex. The signal passes from the sensory nerve to a simple processing center, which initiates a motor command. Seconds are saved, because messages don't have to go the brain, be processed, and get sent back. In matters of survival, the spinal reflexes allow the body to react extraordinarily fast. spinal cord is protected by bony vertebrae and cushioned in cerebrospinal fluid, When the spinal cord is damaged in a particular segment, all lower segments are cut off from the brain, causing paralysis. Therefore, the lower on the spine damage is, the fewer functions an injured individual loses

Homeostasis

state of equilibrium—biological conditions, such as body temperature, are maintained at optimal levels a state of equilibrium, in which biological conditions (such as body temperature) are maintained at optimal levels.

synaptic vesicles

storage site for neurotransmitters

auditory cortex

strip of cortex in the temporal lobe that is responsible for processing auditory information the main area responsible for processing auditory information, is located within the temporal lobe.

motor cortex

strip of cortex involved in planning and coordinating movement which is involved in planning and coordinating movement

amygdala

structure in the limbic system involved in our experience of emotion and tying emotional meaning to our memories involved in our experience of emotion and in tying emotional meaning to our memories.

cerebral cortex

surface of the brain that is associated with our highest mental capabilities very uneven, characterized by a distinctive pattern of folds or bumps, known as gyri (singular: gyrus), and grooves, known as sulci cerebral cortex, which is the outer surface of the brain, is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory. Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.

nervous system can be divided into two major subdivisions:

the central nervous system (CNS) and the peripheral nervous system (PNS)

epigenetics

the science of how the environment influences genetic expression—is changing the conversation. study of gene-environment interactions, such as how the same genotype leads to different phenotypes looks beyond the genotype itself and studies how the same genotype can be expressed in different ways. In other words, researchers study how the same genotype can lead to very different phenotypes. gene expression is often influenced by environmental context in ways that are not entirely obvious. For instance, identical twins share the same genetic information. Identical twins develop from a single fertilized egg that split, so the genetic material is exactly the same in each; in contrast, fraternal twins develop from two different eggs fertilized by different sperm, so the genetic material varies as with non-twin siblings). But even with identical genes, there remains an incredible amount of variability in how gene expression can unfold over the course of each twin's life. Sometimes, one twin will develop a disease and the other will not. In one example, Tiffany, an identical twin, died from cancer at age 7, but her twin, now 19 years old, has never had cancer. Although these individuals share an identical genotype, their phenotypes differ as a result of how that genetic information is expressed over time. The epigenetic perspective is very different from range of reaction, because here the genotype is not fixed and limited.

resting potential

the state of readiness of a neuron membrane's potential between signals Between signals, the neuron membrane's potential is held in a state of readiness, called the resting potential. Like a rubber band stretched out and waiting to spring into action, ions line up on either side of the cell membrane, ready to rush across the membrane when the neuron goes active and the membrane opens its gates (i.e., a sodium-potassium pump that allows movement of ions across the membrane). Ions in high-concentration areas are ready to move to low-concentration areas, and positive ions are ready to move to areas with a negative charge.

corpus callosum

thick band of neural fibers connecting the brain's two hemispheres The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side.

brain is bilateral

two-sided, structure that can be separated into distinct lobes.

genetic environmental correlation

view of gene-environment interaction that asserts our genes affect our environment, and our environment influences the expression of our genes the parents' genes, which the child shares, influence the child's environment, and that environment, in turn, is well suited to support the child's genetic potential.

Hyperpolarization

• Membrane potential becomes more negative • Inhibition

The brain can modify itself in response to injury

• Plasticity • Role of neurogenesis

Multiple genes work together to lead to the expression of traits

• Polygenic effects • Heritability = A statistical estimate of the extent to which variation in a trait within a population is due to genetics

All-or-none principle

• Threshold of excitation

Neurotransmitters are chemical messengers

• Transmit signals from one neuron to another • Different neurons release different types of neurotransmitters that have many different functions (Acetylcholine, beta-endorphin, dopamine, gamma-aminobutyric acid (GABA), Glutamate, Norepinephrine, serotonin)