Ku Psych 104 Chapter 3 CF

Genes and Chromosomes

A gene is the major unit of hereditary transmission. Historically, the term gene has been used to refer to two distinct but related concepts. Genes are sections on a strand of DNA (deoxyribonucleic acid) that are organized into large threads called chromosomes, strands of DNA wound around each other in a double-helix configuration (see FIGURE 3.20). Chromosomes come in pairs, and humans have 23 pairs each. These pairs of chromosomes are similar but not identical: You inherit one of each pair from your father and one from your mother.

Hypothalamus

Basic motivations, Hunger thirst and sexual behavior. And regulates body temperature

Medulla

Breathing and Heartbeat. (Looks like extension of the spinal cord)

Components of Neurons

the cell body, the dendrites, and the axon

Cell Body (Soma)

the largest component of the neuron that coordinates the information-processing tasks and keeps the cell alive. (Functions such as protein synthesis, energy production, and metabolism take place here) Contains a nucleus, which houses chromosomes that contain your DNA, or the genetic blueprint of who you are. The cell body is surrounded by a porous cell membrane that allows some molecules to flow into and out of the cell.

Dizygotic twins share _____ of their genes.

50%

_____ refers to the time following an action potential during which a new action potential cannot be initiated.

A refractory period

The Cerebellum

Behind the medulla is the cerebellum, a large structure of the hindbrain that controls fine motor skills. (Cerebellum is Latin for "little brain," and the structure does look like a small replica of the brain.) The cerebellum orchestrates the proper sequence of movements when we ride a bike, play the piano, or maintain balance while walking and running. It contributes to the fine-tuning of behavior: smoothing our actions to allow their graceful execution rather than initiating the actions (Smetacek, 2002). The initiation of behavior involves other areas of the brain; as you'll recall, different brain systems interact and are interdependent with one another.

Identifying the brain areas that are involved in specific types of motor, cognitive, or emotional processing is best achieved through

Brain imagining

Amygdala

Emotions. Fear, anger and calmness

Endorphins

Endorphins are chemicals that act within the pain pathways and emotion centers of the brain (Keefe et al., 2001). Endorphins help dull the experience of pain and elevate moods. The "runner's high" experienced by many athletes as they push their bodies to painful limits of endurance can be explained by the release of endorphins in the brain (Boecker et al., 2008).

Hippocampus

Forming primitive memories. Knows where we are and how to navigate our environment.

_____ identifies brain activity by applying magnetic pulses to the brain and detecting the twisting of hemoglobin molecules in the blood.

Functional magnetic resonance imaging (fMRI)

Juanita thinks she is having a stroke. Based on knowledge about image resolution, the method of structural image known as _____ would be the BEST method for diagnosing a stroke.

MRI

Auditory cortex

The auditory cortex is responsible for processing sounds so that we can understand them. Ex: I hear a buzzing noise

Norepinephrine and Serotonin

Two related neurotransmitters influence mood and arousal: norepinephrine and serotonin. Norepinephrine is involved in vigilance, or a heightened awareness of dangers in the environment (Ressler & Nemeroff, 1999). Serotonin is involved in the regulation of sleep and wakefulness, eating, and aggressive behavior (Dayan & Huys, 2009; Kroeze & Roth, 1998). Because both neurotransmitters affect mood and arousal, low levels of each have been implicated in mood disorders (Tamminga et al., 2002).

action potential

an electric signal that is conducted along the length of a neuron's axon to a synapse.

Antagonists

are drugs that block the function of a neurotransmitter

Pituitary Gland

Located below the hypothalamus is the pituitary gland, the "master gland" of the body's hormone-producing system, which releases hormones that direct the functions of many other glands in the body. The hypothalamus sends hormonal signals to the pituitary gland, which in turn sends hormonal signals to other glands to control stress, digestive activities, and reproductive processes. For example, when we sense a threat, sensory neurons send signals to the hypothalamus, which stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary gland. ACTH, in turn, stimulates the adrenal glands (above the kidneys) to release hormones that activate the sympathetic nervous system (Selye & Fortier, 1950). As you read earlier in this chapter, the sympathetic nervous system prepares the body to either meet the threat head-on or flee from the situation.

Mirror Neurons

Mirror neurons are active when an animal performs a behavior, such as reaching for or manipulating an object, and they are also activated when another animal observes the first animal as it performs the same behavior. Mirror neurons are found in the frontal lobe (near the motor cortex) and in the parietal lobe (Rizzolatti & Craighero, 2004; Rizzolatti & Sinigaglia, 2012). Neuroimaging studies have shown that mirror neurons are active when people watch someone perform a behavior, such as grasping in midair, and seem to be related to recognizing the goal someone has in carrying out an action

Resting potential

Neurons have a natural electric charge called the resting potential, the difference in electric charge between the inside and outside of a neuron's cell membrane (Kandel, 2000). The resting potential arises from the difference in concentrations of ions inside and outside the neuron's cell membrane (see FIGURE 3.3a). Inside- naturally negative Outside- Positive

The Midbrain

Sitting on top of the hindbrain is the midbrain, which is relatively small in humans. As you can see in FIGURE 3.13, the midbrain contains two main structures: the tectum and the tegmentum. These structures help orient an organism in the environment, and they guide movement towards or away from stimuli. For example, when you're studying in a quiet room and you hear a click behind and to the right of you, your body will swivel and orient to the direction of the sound; this is your tectum in action.

Amygdala

The amygdala (from Latin for "almond," also due to its shape), located at the tip of each horn of the hippocampus, plays a central role in many emotional processes, particularly the formation of emotional memories (Aggleton, 1992). When we are in emotionally arousing situations, the amygdala stimulates the hippocampus to remember many details surrounding the situation (Kensinger & Schacter, 2005). For example, people who lived through the terrorist attacks of September 11, 2001, remember vivid details about where they were, what they were doing, and how they felt when they heard the news, even years later (Hirst et al., 2009).

Temporal lobe

The temporal lobe, located on the lower side of each hemisphere, is responsible for hearing and language. The primary auditory cortex in the temporal lobe is analogous to the somatosensory cortex in the parietal lobe and the primary visual areas of the occipital lobe: It receives sensory information from the ears based on the frequencies of sounds (Recanzone & Sutter, 2008). Secondary areas of the temporal lobe then process the information into meaningful units, such as speech and words. The temporal lobe also houses the visual association areas that interpret the meaning of visual stimuli and help us recognize common objects in the environment (Martin, 2007).

Which technique does NOT measure blood flow to different areas of the brain?

an electroencephalograph (EEG)

Agonists

are drugs that increase the action of a neurotransmitter.

While Jamal eats, he always chews with his mouth closed. This requires that he breathe through his nose. However, Jamal does not have to focus on this because his _____ nervous system allows him to do it automatically.

autonomic

A person who incurs damage to the basal ganglia is MOST likely to:

be unable to ride a bike

Axons

carries information to other neurons, muscles, or glands. Axons can be very long, even stretching up to a meter from the base of the spinal cord down to the big toe. See terminal buttons

Motor Neurons

carry signals from the spinal cord to the muscles to produce movement. These neurons often have long axons that can stretch to muscles at our extremities.

Neurons

cells in the nervous system that communicate with one another to perform information-processing tasks. 100 billion nerve cells in your brain that perform a variety of tasks to allow you to function as a human being. All of your thoughts, feelings, and behaviors spring from cells in the brain that take in information and produce some kind of output trillions of times a day.

Neurotransmitters are chemical messengers that carry signals within the brain. Based on their location, these would be a component of the _____ nervous system.

central

When specific mechanisms in the synapse destroy a neurotransmitter, the process is called:

enzyme deactivation

Epigenetics

epigenetics: environmental influences that determine whether or not genes are expressed, or the degree to which they are expressed, without altering the basic DNA sequences that constitute the genes themselves. To understand how epigenetic influences work, think about DNA as analogous to a script for a play or a movie. The biologist Nessa Carey (2012) offers the example of Shakespeare's Romeo and Juliet, which was made into a movie in 1936 starring Leslie Howard and Norma Shearer, and in 1996 starring Leonardo DiCaprio and Claire Danes. Shakespeare's script formed the basis of both films, but the directors of the two films used the script in different ways, and the actors in the two films gave different performances. Thus, the final products were different from one another, even though Shakespeare's original script still exists.

The first true central nervous system appeared in

flatworms

The basic levels of the brain become visible during the _____ week of pregnancy.

fourth

Researchers can observe relationships between energy consumption in certain brain areas and specific cognitive and behavioral events using _____________.

functional brain imaging

A researcher is using a strong magnet to track blood-oxygen changes in participants' brains as they complete decision-making tasks. The researcher is using _____ to examine the brain's activity.

functional magnetic resonance imaging

The reticular activating system is located in the _____. It regulates _____.

hindbrain; arousal

Acetylcholine (ACh)

is a neurotransmitter involved in a number of functions, including voluntary motor control. Acetylcholine is found in neurons of the brain and in the synapses where axons connect to muscles and body organs, such as the heart. Acetylcholine contributes to the regulation of attention, learning, sleeping, dreaming, and memory (Gais & Born, 2004; Hasselmo, 2006; Wrenn et al., 2006). Alzheimer's disease, a medical condition involving severe memory impairments (Salmon & Bondi, 2009), is associated with the deterioration of ACh-producing neurons.

Nervous System

nervous system is an interacting network of neurons that conveys electrochemical information throughout the body. 2 divisions

Maria encounters a wolverine in the foothills and escapes by running very quickly to her car. After reaching the safety of her car, her heart rate and breathing begin to slow down because of her _____ nervous system.

parasympathetic

Genes set the _____________ that a given individual can express.

range of variation

Dendrites

receive information from other neurons and relay it to the cell body. The term dendrite comes from the Greek word for "tree"; indeed, most neurons have many dendrites that look like tree branches see receptors

Sensory Neurons

receive information from the external world and convey this information to the brain via the spinal cord. They have specialized endings on their dendrites that receive signals for light, sound, touch, taste, and smell

Unlike the autonomic nervous system, humans have voluntary control over the _____ nervous system.

somatic

The _____ is the element of the central nervous system that allows people to perform functions such as breathing, walking, and moving muscles.

spinal chord

Anastasia loves neuroscience and is hoping that someday she will get the opportunity to see images of her different brain structures. To see this, she will need to go somewhere that uses:

structural brain imaging

Thalamus

thalamus relays and filters information from the senses and transmits the information to the cerebral cortex

When spinal reflexes occur, interneurons relay sensory input to the _____ in the spinal cord and fast contractions can then occur.

motor neurons

Reticular Formation

Alertness and Attention. Those with injuries to this area have problems focusing on tasks. Arousal

terminal buttons

Axons usually end in terminal buttons, knob-like structures that branch out from an axon. A terminal button is filled with tiny vesicles, or "bags," that contain neurotransmitters, chemicals that transmit information across the synapse to a receiving neuron's dendrites.

During the course of embryonic brain growth, the _____________ undergoes the greatest development.

Cerebral Cortex

Dopamine

Dopamine is a neurotransmitter that regulates motor behavior, motivation, pleasure, and emotional arousal. Because of its role in associating actions with rewards, dopamine plays a role in drug addiction (Baler & Volkow, 2006). High levels of dopamine have been linked to schizophrenia (Winterer & Weinberger, 2004), whereas low levels have been linked to Parkinson's disease.

The benefit of using a(n) _____ is that it allows researchers to make fundamental discoveries about the nature of sleep.

EEG

functional recording

Uses fMRI or PET scan; good spatial resolution; okay temporal resolution --> Problem with fMRI: takes a few seconds to see the changes in the brain.

Glutamate

Glutamate is the major excitatory neurotransmitter in the brain, meaning that it enhances the transmission of information between neurons. GABA (gamma-aminobutyric acid), in contrast, is the primary inhibitory neurotransmitter in the brain, meaning that it tends to stop the firing of neurons. Too much glutamate, or too little GABA, can cause neurons to become overactive, causing seizures.

Cerebellum

Helps control highly practiced motor movements. Classical Conditioning. ADHD Association

Pons

Helps make well practiced body movements (Right above the Medulla) Sleep

The Hindbrains

If you follow the spinal cord from your tailbone to where it enters your skull, you'll find it difficult to determine where your spinal cord ends and your brain begins. That's because the spinal cord is continuous with the hindbrain, an area of the brain that coordinates information coming into and out of the spinal cord. The hindbrain looks like a stalk on which the rest of the brain sits, and it controls the most basic functions of life: respiration, alertness, and motor skills. The structures that make up the hindbrain include the medulla, the reticular formation, the cerebellum, and the pons

myelin sheath

In many neurons, the axon is covered by a myelin sheath, an insulating layer of fatty material. The myelin sheath is composed of glial cells (named for the Greek word for "glue"), which are support cells found in the nervous system.

Brain Damage: Frontal Lobe Phineas Gage

Phineas Gage was a muscular 25-year-old railroad worker. On September 13, 1848, in Cavendish, Vermont, he was packing an explosive charge into a crevice in a rock when the powder exploded, driving a 3-foot, 13-pound iron rod through his head at high speed (Harlow, 1848). the rod entered through his lower left jaw and exited through the middle top of his head. Incredibly, Gage lived to tell the tale. But his personality underwent a significant change. Phineas Gage Phineas Gage's traumatic accident allowed researchers to investigate the functions of the frontal lobe and its connections with emotion centers in the subcortical structures. The likely path of the metal rod through Gage's skull is reconstructed here. Before the accident, Gage had been mild mannered, quiet, conscientious—and a hard worker. After the accident, however, he became irritable, irresponsible, indecisive, and given to profanity. The sad decline of Gage's personality and emotional life nonetheless provided an unexpected benefit to psychology. His case study was the first to allow researchers to investigate the hypothesis that the frontal lobe is involved in emotion regulation, planning, and decision making. Furthermore, because the connections between the frontal lobe and subcortical structures were affected, scientists were able to understand better how the amygdala, hippocampus, and related brain structures interacted with the cerebral cortex (Damasio, 2005).

Thalamus

Receives input from all sensory systems except smells. Passes the info on to the proper area of the cortex

Mid Brain

Sensory information and muscle movement. Lets us know where we are, and directs our eyes. Responds reflexively to to sounds

Glial Cells

Support cells found in the nervous system - Although there are 100 billion neurons busily processing information in your brain, there are 10 to 50 times that many glial cells serving a variety of functions. Some glial cells digest parts of dead neurons, others provide physical and nutritional support for neurons, and others form myelin to help the axon carry information more efficiently. An axon insulated with myelin can more efficiently transmit signals to other neurons, organs, or muscles

Chan is hiking in the woods when he comes across a tiger. As he decides whether he should run away, his _____ nervous system works to coordinate his body.

Sympathetic

Central Nervous system (CNS)

The central nervous system (CNS) is composed of the brain and spinal cord. The central nervous system receives sensory information from the external world, processes and coordinates this information, and sends commands to the skeletal and muscular systems for action. spinal reflexes: simple pathways in the nervous system that rapidly generate muscle contractions. If you touch a hot stove, the sensory neurons that register pain send inputs directly into the spinal cord

Stages of Communication of information within and between neurons Conduction transmission

The communication of information within and between neurons proceeds in two stages. First, information has to travel inside the neuron via an electrical signal that travels from the dendrite to the cell body to the axon—a process called conduction. Then, the signal has to be passed from one neuron to another, usually via chemical messengers traveling across the synapse—a process called transmission. Let's look at both processes in more detail.

receptors

The dendrites of the receiving neuron contain receptors, parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electric signal.

1. Organization across Hemispheres.

The first level of organization divides the cortex into the left and right hemispheres. The two hemispheres are more or less symmetrical in their appearance and, to some extent, in their functions. However, each hemisphere controls the functions of the opposite side of the body. This is called contralateral control, meaning that your right cerebral hemisphere perceives stimuli from and controls movements on the left side of your body, whereas your left cerebral hemisphere perceives stimuli from and controls movement on the right side of your body. The cerebral hemispheres are connected to each other by bundles of axons that make possible communication between parallel areas of the cortex in each half. The largest of these bundles is the corpus callosum, which connects large areas of the cerebral cortex on each side of the brain and supports communication of information across the hemispheres. This means that information received in the right hemisphere, for example, can pass across the corpus callosum to the left hemisphere.

The forebrain

The forebrain is the highest level of the brain—literally and figuratively—and controls complex cognitive, emotional, sensory, and motor functions. The forebrain itself is divided into two main sections: the subcortical structures and the cerebral cortex. The subcortical structures: are areas of the forebrain housed under the cerebral cortex near the center of the brain (see FIGURE 3.14). They include the thalamus, hypothalamus, pituitary gland, hippocampus, amygdala, and basal ganglia, and these structures play an important role in relaying information throughout the brain, as well as performing specific tasks that allow us to think, feel, and behave as humans. If you imagine sticking an index finger in each of your ears and pushing inward until they touch, that's about where you'd find the subcortical structures

Frontal lobe

The frontal lobe, which sits behind the forehead, has specialized areas for movement, abstract thinking, planning, memory, and judgment. As you just read, it contains the motor cortex, which coordinates movements of muscle groups throughout the body. Other areas in the frontal lobe coordinate thought processes that help us manipulate information and retrieve memories, which we can use to plan our behaviors and interact socially with others. In short, the frontal cortex allows us to do the kind of thinking, imagining, planning, and anticipating that sets humans apart from most other species (Schoenemann, Sheenan, & Glotzer, 2005; Stuss & Benson, 1986; Suddendorf & Corballis, 2007).

Hippocampus

The hippocampus (from Latin for "sea horse," due to its shape) is critical for creating new memories and integrating them into a network of knowledge so that they can be stored indefinitely in other parts of the cerebral cortex. Individuals with damage to the hippocampus can acquire new information and keep it in awareness for a few seconds, but as soon as they are distracted, they forget the information and the experience that produced it (Scoville & Milner, 1957; Squire, 2009). This kind of disruption is limited to everyday memory for facts and events that we can bring to consciousness; memory of learned habitual routines or emotional reactions remains intact (Squire, Knowlton, & Musen, 1993). As an example, people with damage to the hippocampus can remember how to drive and talk, but they cannot recall where they have recently driven or a conversation they have just had.

Hypothalamus

The hypothalamus, located below the thalamus (hypo- is Greek for "under"), regulates body temperature, hunger, thirst, and sexual behavior. For example, lesions to some areas of the hypothalamus result in overeating, whereas lesions to other areas leave an animal with no desire for food at all (Berthoud & Morrison, 2008).

The Pons

The last major area of the hindbrain is the pons, a structure that relays information from the cerebellum to the rest of the brain. (Pons means "bridge" in Latin.) Although the detailed functions of the pons remain poorly understood, it essentially acts as a relay station or bridge between the cerebellum and other structures in the brain. cerebellum: A large structure of the hindbrain that controls fine motor skills.

The Medulla

The medulla is an extension of the spinal cord into the skull that coordinates heart rate, circulation, and respiration. Beginning inside the medulla and extending upward is a small cluster of neurons called the reticular formation, which regulates sleep, wakefulness, and levels of arousal. In one early experiment, researchers stimulated the reticular formation of a sleeping cat. This caused the animal to awaken almost instantaneously and remain alert. Conversely, severing the connections between the reticular formation and the rest of the brain caused the animal to lapse into an irreversible coma (Moruzzi & Magoun, 1949). The reticular formation maintains the same delicate balance between alertness and unconsciousness in humans. In fact, many general anesthetics work by reducing activity in the reticular formation, rendering the patient unconscious. reticular formation: which regulates sleep, wakefulness, and levels of arousal.

Motor cortex

The motor cortex initiates voluntary movements such as reaching for an object. Ex: My finger jumped but I didn't intend to move it.

Occipital lobe

The occipital lobe, located at the back of the cerebral cortex, processes visual information. Sensory receptors in the eyes send information to the thalamus, which in turn sends information to the primary areas of the occipital lobe, where simple features of the stimulus are extracted, such as the location and orientation of an object's edges (see the Sensation and Perception chapter for more details). These features are then processed still further, leading to comprehension of what's being seen. Damage to the primary visual areas of the occipital lobe can leave a person with partial or complete blindness. Information still enters the eyes, but without the ability to process and make sense of the information in the cerebral cortex, the information is as good as lost (Zeki, 2001).

The Parietal lobe

The parietal lobe, located in front of the occipital lobe, carries out functions that include processing information about touch. The parietal lobe contains the somatosensory cortex, a strip of brain tissue running from the top of the brain down to the sides (see FIGURE 3.17). Within each hemisphere, the somatosensory cortex represents the skin areas on the contralateral surface of the body. Each part of the somatosensory cortex maps onto a particular part of the body. If a body area is more sensitive, a larger part of the somatosensory cortex is devoted to it. For example, the part of the somatosensory cortex that corresponds to the lips and tongue is larger than the area corresponding to the feet. The somatosensory cortex can be illustrated as a distorted figure, called a homunculus ("little man"), in which the body parts are rendered according to how much of the somatosensory cortex is devoted to them (Penfield & Rasmussen, 1950). Directly in front of the somatosensory cortex, in the frontal lobe, is a parallel strip of brain tissue called the motor cortex. Like the somatosensory cortex, the motor cortex has different parts that correspond to different body parts. The motor cortex initiates voluntary movements and sends messages to the basal ganglia, cerebellum, and spinal cord. The motor and somatosensory cortices, then, are like sending and receiving areas of the cerebral cortex, taking in information and sending out commands.

Peripheral Nervous System (PNS)

The peripheral nervous system (PNS) connects the central nervous system to the body's organs and muscles. 2 Division Somatic Nervous System: is a set of nerves that conveys information between voluntary muscles and the central nervous system. Humans have conscious control over this system and use it to perceive, think, and coordinate their behaviors. For example, reaching for your morning cup of coffee involves the elegantly orchestrated activities of the somatic nervous system: Information from the receptors in your eyes travels to your brain, registering that a cup is on the table; signals from your brain travel to the muscles in your arm and hand; feedback from those muscles tells your brain that the cup has been grasped; and so on. Autonomic Nervous System: is a set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, and glands. As suggested by its name, this system works on its own to regulate bodily systems, largely outside of conscious control. The ANS has two major subdivisions, the sympathetic nervous system and the parasympathetic nervous system. Each exerts a different type of control on the body. The sympathetic nervous system is a set of nerves that prepares the body for action in challenging or threatening situations, and the parasympathetic nervous system helps the body return to a normal resting state

2. Organization within Hemispheres.

The second level of organization in the cerebral cortex distinguishes the functions of the different regions within each hemisphere of the brain. Each hemisphere of the cerebral cortex is divided into four areas, or lobes: From back to front, these are the occipital lobe, the parietal lobe, the temporal lobe, and the frontal lobe, as shown in FIGURE 3.15.

Somatosensory cortex

The somatosensory cortex receives information such as pressure, temperature, and pain from the body. In addition, it receives feedback from the muscles and joints. Ex: Tingle in my hand

3. Organization within Specific Lobes

The third level of organization in the cerebral cortex involves the representation of information within specific lobes in the cortex. There is a hierarchy of processing stages from primary areas that handle fine details of information all the way up to association areas, which are composed of neurons that help provide sense and meaning to information registered in the cortex. For example, neurons in the primary visual cortex are highly specialized: Some detect features of the environment that are in a horizontal orientation, others detect movement, and still others process information about human versus nonhuman forms. Secondary areas interpret the information extracted by these primary areas (shape, motion, etc.) to make sense of what's being perceived—in this case, perhaps a large cat leaping toward your face. Similarly, neurons in the primary auditory cortex register sound frequencies, but it's the association areas of the temporal lobe that allow you to turn those noises into the meaning of your friend screaming, "Look out for the cat!" Association areas, then, help stitch together the threads of information in the various parts of the cortex to produce a meaningful understanding of what's being registered in the brain.

Visual cortex

The visual cortex is responsible for processing information from our eyes that we consciously perceive. Ex: I see flashes of light

Types and functions of neurotransmitters

Today, we know that some 60 chemicals play a role in transmitting information throughout the brain and body and differentially affect thought, feeling, and behavior, but a few major classes seem particularly important.

structural recording

Uses MRI, DTI(water), CT; Good spacial resolution (Best); bad temporal resolution.

Cerebral Cortex

cerebral cortex, which is the outermost layer of the brain, visible to the naked eye, and divided into two hemispheres. The cortex is the highest level of the brain, and it is responsible for the most complex aspects of perception, emotion, movement, and thought (Fuster, 2003). It sits over the rest of the brain, like a mushroom cap shielding the underside and stem, and it is the wrinkled surface you see when looking at the brain with the naked eye. The cerebral cortex occupies roughly the area of a newspaper page. Fitting that much cortex into a human skull is a tough task. But if you crumple a sheet of newspaper, you'll see that the same surface area now fits compactly into a much smaller space. The cortex, with its wrinkles and folds, holds a lot of brainpower in a relatively small package that fits comfortably inside the human skull (see FIGURE 3.15). The cerebral cortex can be best understood by studying its functions according to three levels of its organization: 1) across its two hemispheres; 2) within each hemisphere; and 3) within the specific cortical areas.

Robert was a professional hockey player for 12 years. During his career, he experienced several concussions which caused severe headaches. Robert has been retired for 10 years and is experiencing memory and comprehension problems, excruciating migraines, and bouts of depression. Robert may be diagnosed with _____.

chronic traumatic encephalopathy

Interneurons

most of the nervous system is composed of the third type of neuron, interneurons, which connect sensory neurons, motor neurons, or other interneurons. Some interneurons carry information from sensory neurons into the nervous system, others carry information from the nervous system to motor neurons, and still others perform a variety of information-processing functions within the nervous system.

People who suffer from demyelinating diseases have neurons that communicate _____ than people without these diseases.

less efficiently

Karen is watching a horror movie, and when a really gory scene occurs, she cannot help but turn away. It is MOST likely that the small area of her brain called the _____ has caused her to do this.

midbrain

_____ syndrome refers to a phenomenon in which amputee patients continue to experience sensations where the missing body part would be.

phantom limb

Amy, a split-brain patient, could NOT:

pick an object up with her left hand that was presented to her right field of vision.

Chan lost his thumb in an unfortunate hunting incident. A few years after the accident, he had a brain scan and it demonstrated that areas of his brain that previously responded when he moved his thumb now responded when he moved his index finger. This change demonstrates the _____ of the brain.

plasticity

The _____ serves as a bridge from the cerebellum to the rest of the brain.

pons

synapse

the junction or region between the axon of one neuron and the dendrites or cell body of another. most adults have 100 to 500 trillion synapses.

Split-brain studies have revealed that

the two hemispheres perform different functions but can work together by means of the corpus callosum.

David Hubel and Torsten Wiesel measured the response of individual neurons and found that neurons in the primary _____ cortex are activated when a contrast between light and dark occurs.

visual

Myelin Sheath Examples of Deterioration

with demyelinating diseases, such as multiple sclerosis, the myelin sheath deteriorates, slowing the transmission of information from one neuron to another (Schwartz & Westbrook, 2000). This kind of damage leads to a variety of problems, including loss of feeling in the limbs, partial blindness, and difficulties in coordinated movement and cognition (Butler, Corboy, & Filley, 2009).