CH. 1 Structure and Function: Neuroanatomy and Research Methods Flashcards
Neurons
NEURONS (or NERVE CELLS)– Arranged into the circuits that underlie all forms of behavior, from simple reflexes to complex cognition. The basic unit of the nervous system, each composed of receptive extensions called dendrites, an integrating cell body, a conducting axon, and a transmitting axon terminal.
- All of your organs and muscles are in communication with the nervous system, which, like all other living tissue, is made up of highly specialized cells.
- . Each neuron receives inputs from many other cells, integrates those inputs, and then distributes the processed information to other neurons
- Your brain contains 80−90 billion of these.
GILIAL CELLS (sometimes just GLIA) – Are found in the human brain, mostly providing a variety of support functions but also participating in information processing. Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain.
SYNAPSES – The cellular location at which information is transmitted from a neuron to another cell.
- Although neurons come very close together, they are not quite continuous with one another.
- (1) neurons and other cells of the brain are structurally, metabolically, and functionally independent, and (2) information is transmitted from neuron to neuron across tiny gaps, later named SYNAPSES.
Neuron Has Four Principal Divisions
Neuron Has Four Principal Divisions:
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Input zone – Where neurons collect and process information, either from the environment or from other cells. At cellular extensions called DENDRITES –neurons receive information via synapses from other neurons.
- Dendrites may be covered in DENDRITIC SPINES, small projections from the surface of the dendrite that add additional space for synapses
- Information from other neurons is passed to the dendrites and cell body via synapses.
- INTEGRATION ZONE – Where the decision to produce a neural signal is made. The neuron’s CELL BODY (or soma, plural somata) integrates (combines) the information that has been received to determine whether or not to send a signal of its own.
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CONDUCTION ZONE – Where information can be electrically transmitted over great distances.
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AXON (or NERVE FIBER) – Carries the neuron’s own electrical signals away from the cell body.
- Toward its end, the axon may split into multiple branches called AXON COLLATERALS.
- Each axon terminal synapses onto another cell in order to transmit information.
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AXON (or NERVE FIBER) – Carries the neuron’s own electrical signals away from the cell body.
- OUTPUT ZONES – Where the neuron transfers information to other cells. Specialized swellings at the ends of the axon, called AXON TERMINALS (or synaptic boutons), transmit the neuron’s signals across synapses to other cells.
Neurons Are Classified into Three Principal Types
Neurons Are Classified into Three Principal Types:
MOTOR NEURONS – Large with long axons reaching out to synapse on muscles, causing muscular contractions.
SENSORY NEURONS – Specialized to gather sensory information. A nerve cell that is directly affected by changes in the environment, such as light, odor, or touch.
INTERNEURONS – Analyze information gathered from one set of neurons and communicate with others. A nerve cell that is neither a sensory neuron nor a motor neuron. Interneurons receive input from and send output to other neurons.
- In general, larger neurons tend to have more-complex inputs and outputs, cover greater distances, and/or convey information more rapidly than smaller neurons.
In addition to size, neuroscientists classify neurons into THREE GENERAL CATEGORIES OF SHAPE, each specialized for a particular kind of information processing (FIGURE 1.3):
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MULTIPOLAR NEURONS – Many dendrites and a single axon.
- They are the most common type of neuron.
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BIPOLAR NEURONS – Have a single dendrite at one end of the cell and a single axon at the other end.
- Especially common in sensory systems, such as vision.
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UNIPOLAR NEURONS (also called monopolar neurons) – Have a single extension (or process), usually thought of as an axon, that branches in two directions after leaving the cell body. One end is the input zone with branches like dendrites; the other, the output zone with terminals.
- Transmit touch information from the body into the spinal cord.
- In all three types of neurons, the dendrites comprise the input zone.
- In multipolar and bipolar neurons, the cell body also receives synaptic inputs, so it is also part of the input zone
Information is Transmitted Through Synapses
INFORMATION IS TRANSMITTED THROUGH SYNAPSES – A neuron’s dendrites reflect the complexity of the inputs that are received.
PRESYNAPTIC – Referring to the “transmitting” side of a synapse.
POSTSYNAPTIC – Referring to the region of a synapse that receives and responds to neurotransmitter.
- At each synapse, information is transmitted from an axon terminal of a presynaptic neuron to the receptive surface of a postsynaptic neuron.
- A synapse can be divided into three principal components.
PRESYNAPTIC MEMBRANE – Of the axon terminal of the presynaptic (i.e., transmitting) neuron– (output from the neuron). Transmits information by releasing neurotransmitter.
SYNAPTIC CLEFT – The space between the presynaptic and postsynaptic neurons at a synapse. a gap of about 20–40 nanometers that separates the presynaptic and postsynaptic neurons. - (Across the gap)
POSTSYNAPTIC MEMBRANE – Membrane on the surface of a neuron that receives information by responding to neurotransmitter from a presynaptic neuron. On the dendrite or cell body of the postsynaptic (i.e., receiving) neuron.–(Receives input from other neuron)
SYNAPTIC VESICLE – A small, spherical structure that contains molecules of neurotransmitter. Each synaptic vesicle contains molecules of neurotransmitter.
- Presynaptic axon terminals contain many tiny hollow spheres called synaptic vesicles.
NEUROTRANSMITTER – The special chemical with which a presynaptic neuron communicates with postsynaptic cells. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.
NEUROTRANSMITTER RECEPTOR – That stud the postsynaptic membrane. Also called simply receptor. A specialized protein that selectively senses and reacts to molecules of a corresponding neurotransmitter or hormone.
- In response to electrical activity in the axon, synaptic vesicles fuse to the presynaptic membrane and then rupture, releasing their payload of neurotransmitter molecules into the synaptic cleft. After crossing the cleft, the released neurotransmitter molecules interact with matching neurotransmitter receptors.
- The receptors capture and react to molecules of the neurotransmitter, altering the level of excitation of the postsynaptic neuron.
- This action affects the likelihood that the postsynaptic neuron will in turn release its own neurotransmitter from its axon terminals.
- Molecules of neurotransmitter generally do not enter the postsynaptic neuron; they simply bind to the outside of the receptors momentarily to induce a response, and then detach and diffuse away.
NEUROPLASTICITY – The configuration of synapses on a neuron’s dendrites and cell body is constantly changing—synapses come and go, dendrites change their shapes, dendritic spines wax and wane—in response to new patterns of synaptic activity and the formation of new neural circuits. The ability of the nervous system to change in response to experience or the environment.
The Axon Integrates and Then Transmits Information:
AXON HILLOCK – The axon hillock has unique properties that allow it to gather and integrate the information arriving from the synapses on the dendrites and cell body. this process determines when the neuron will produce neural signals of its own. Cone-shaped area on the cell body from which the axon originates.
INNERVATE – To provide neural input to.
- The neuron’s output information, encoded in a stream of electrical impulses, then races down the axon toward the targets that the neuron is said to innervate.
AXON TRANSPORT – The transportation of materials from the neuronal cell body toward the axon terminals, and from the axon terminals back toward the cell body. The axon is a hollow tube, and various important substances, such as enzymes and structural proteins, are conveyed through the interior of the axon from the cell body, where they are produced, to the axon terminals, where they are used.
- it’s important to understand that the axon has two quite different functions: the rapid transmission of electrical signals along the outer Watson/Breedlove membrane (like a wire), and the much slower transportation of substances within The Mind’s Machine the Foundations axon, to of Brain and from the axon terminals (like a pipe).
Gilial Cells
GILIAL CELLS – Protect and assist neurons. Glial cells directly affect neuronal processes by providing neurons with raw materials, chemical signals, and specialized structural components.
Four main kinds of glial cells:
- Two of these four types of glia OLIGODENDROCYTESs and SCHWANN CELLS—wrap around successive segments of axon to insulate them with a fatty substance called MYELIN.
OLIGODENDROCYTEE – Type of glial cell that forms myelin in the central nervous system.
- Within the brain and spinal cord, myelination is provided by the oligodendrocytes, each cell typically supplying myelin beads to several nearby axons.
SCHWANN CELL – Type of glial cell that forms myelin in the peripheral nervous system.
- In the rest of the body, it is Schwann cells that do the ensheathing, with each Schwann cell wrapping itself around a segment of one axon to provide a single bead of myelin.
MYELIN – The fatty insulation around an axon, formed by glial cells. This sheath boosts the speed at which nerve impulses are conducted. A fatty substance.
- MYELIN SHEATH – Give an axon the appearance of a string of elongated slender beads
- NODE OF RANVIER – A gap between successive segments of the myelin sheath where the axon membrane is exposed. Small uninsulated patches of axonal membrane.
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MYELINATION – Result: a large increase in the speed with which electrical signals pass down the axon, jumping from one node of Ranvier to the next.
- Provided by oligodendrocytes or by Schwann cells.
The other two types of glial cells:
ASTROCYTES – A star-shaped glial cell with numerous processes (extensions) that run in all directions. Astrocytes help to form the tough outer membranes that swaddle the brain, and they also secrete chemical signals that affect synaptic transmission and the formation of synapses.
- eave around and between neurons with tentacle-like extensions.
- Some astrocytes stretch between neurons and fine blood vessels, controlling local blood flow to increase the amount of blood reaching more-active brain regions.
MICROGILIAL CELLS – Extremely small motile glial cells that remove cellular debris from injured or dead cells. Primary job appears to be to contain and clean up sites of injury.
- In contrast, microglial cells (or microglia) are tiny and mobile.
- However, astrocytes and microglia may also worsen some problems, such as harmful swelling (edema) following brain injury, and degenerative processes like Alzheimer’s disease (Chapter 4) and Parkinson’s disease.
The Nervous System Extends Throughout The Body
The Nervous System Extends Throughout The Body:
GROSS NEUROANATOMY – oO the nervous system—the neural structures that are visible to the unaided eye.
CENTRAL NERVOUS SYSTEM (CNS) – consisting of the brain and spinal cord.
PERIPHERAL NERVOUS SYSTEM – Everything else– includes all the nerves and neurons outside the brain and spinal cord.
THE PERIPHERAL NERVOUS SYSTEM HAS TWO DIVISIONS:
NERVES – Collections of axons bundled together—that extend throughout the body. A collection of axons bundled together outside the central nervous system.
- MOTOR NERVES – A nerve that transmits information from the central nervous system to the muscles and glands. Transmit information from the spinal cord and brain to muscles and glands.
- SENSORY NERVES – Convey information from the body to the CNS.
Nerves Of The Body are Divided Into Two Distinct Systems:
- SOMATIC NERVOUS SYSTEM – Consists of nerves that interconnect the brain and the major muscles and sensory systems of the body. A part of the peripheral nervous system that supplies neural connections mostly to the skeletal muscles and sensory systems of the body. It consists of CRANIAL NERVES and SPINAL NERVES.
- AUTONOMIC NERVOUS SYSTEM – Consists of nerves that connect primarily to the viscera (internal organs). A part of the peripheral nervous system that provides the main neural connections to the internal organs.
SOMATIC NERVOUS SYSTEM
SOMATIC NERVOUS SYSTEM – The somatic nervous system is the main pathway through which the brain controls movement and receives sensory information from the body and from the sensory organs of the head.
The nerves that make up the somatic nervous system form two anatomical groups: the cranial nerves and the spinal nerves.
CRANIAL NERVES – That arise from the brain and innervate the head, neck, and visceral organs directly, without ever joining the spinal cord.
We each have 12 pairs (left and right) of cranial nerves.
olfactory (I) nerves transmit information about smell
optic (II) nerves carry visual information from the eyes.
vestibulocochlear (VIII) nerves – information about hearing and balance.
muscles to move the eyes
Control neck muscles
Control the tongue
Transmit facial sensation
Control the chewing muscles
Control facial muscles
Taste sensation
VAGUS NERVE – Nerve extends far from the head, running to the heart, liver, and intestines, and other organs.
SPINAL NERVE – A nerve that emerges from the spinal cord
- Along the length of the spinal cord, an additional 31 pairs of spinal nerves—each pair serves each side of the body.
- Each spinal nerve is made up of a group of motor fibers, projecting from the ventral (front) part of the spinal cord.
- Spinal nerves are named according to the segments of the spinal cord to which they are connected. There are:
- CERVICAL (neck) - 8
- THORACIC (torso) - 12
- LUMBAR (lower back) - 5
- SACRAL (pelvic) - 5
- COCCYGEAL (bottom) - 1
- Example, the nerve connected to the 12th thoracic segment is called T12,
- After leaving the spinal cord, axons from the spinal nerves spread out in the body and may merge with axons from different spinal nerves to form the various peripheral nerves.
Autonomic Nervous System
AUTONOMIC NERVOUS SYSTEM – The brain’s main system for controlling the organs of the body.
- The activity of our organs is determined by a balance between the two major divisions of the autonomic nervous system—called the sympathetic and parasympathetic nervous systems—that act more or less in opposition to each other.
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SYMPATHETIC NERVOUS SYSTEM – The part of the autonomic nervous system that generally prepares the body for action. sympathetic innervation prepares the body for immediate action: blood pressure increases, the pupils of the eyes widen, the heart quickens, and so on. This set of reactions is sometimes called the fight-or-flight response.
- Exit from the middle parts of the spinal cord, travel a short distance, and then innervate the sympathetic ganglia (small clusters of neurons found outside the CNS), which run in two chains along the spinal column, one on each side.
- Axons from the sympathetic ganglia then spread throughout the body, innervating all the major organ systems.
In contrast to the effects of sympathetic activity, the:
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PARASYMPATHETIC NERVOUS SYSTEM – The part of the autonomic nervous system that generally prepares the body to relax and recuperate.
- Generally helps the body to relax, recuperate, and prepare for future action sometimes called the rest-and-digest response. Anatomically, nerves of the parasympathetic Watson/Breedlove system originate in the brainstem
- The sympathetic and parasympathetic systems have very different effects on individual organs because the organs receive different neurotransmitters from the two opposing systems.
Central Nervous System
CENTRAL NERVOUS SYSTEM – Consists of the brain and the spinal cord. The spinal cord funnels sensory information from the body up to the brain and conveys the brain’s motor commands out to the body. The spinal cord also contains circuits that perform local processing and control simple units of behavior, such as reflexes.
CONVENTIONS FOR DESCRIBING THE ANATOMY OF THE BRAIN:
The Three Planes of Dissection are:
- SAGITTAL PLANE – Plane that divides the brain into right and left portions.
- CORONAL PLANE (FRONTAL PLANE) – Plane that divides front (anterior) from back (posterior).
- HORIZONTAL PLANE – Divides between upper and lower parts.
Locations in the nervous system are described using directional terms:
MEDIAL – Toward the middle.
LATERAL – Toward the side.
IPSILATERAL – On the same side.
CONTALATERAL – On the opposite side.
SUPERIOR – Above.
INFERIOR – Below.
BASAL – Toward the bottom.
ANTERIOR – Locations toward the front of the brain.
POSTERIOR – Locations toward the rear.
PROXIMAL – Near.
DISTAL – Far or toward the end of the limb.
AFFERENT – A nerve or pathway is afferent if it carries information into a region that we’re interested in. Carrying action potentials toward the brain, or toward one region of interest from another region of interest.
EFFERENT – If it carries information away from the region of interest (a handy way to remember this is that efferents exit but afferents arrive. Carrying action potentials away from the brain, or away from one region of interest toward another region of interest.
DORSAL – Towards the back.
VENTRAL – Towards the belly.
GRAY MATTER – Receives and processes information.
WHITE MATTER – Matter mostly transmits information.
The Outer Surface of The Brain:
CEREBRAL HEMISPHERE – One of the two halves—right or left—of the forebrain.
CEREBRAL CORTEX – The outer covering of the cerebral hemispheres, which consists largely of nerve cell bodies and their branches. The brain is its lumpy, convoluted surface—the result of elaborate folding of a thick sheet of tissue, mostly the dendrites, cell bodies, and axonal projections of neurons.
GYRI (SINGULAR GYRUS) – A ridged or raised portion of the cortical surface.
- Are separated from each other by crevices called:
SULCI (SULCUS) – A crevice or valley of the cortical surface.
The pattern of folding is not random; in fact, it is similar enough between brains that we can name the various gyri and sulci and group them together into lobes:
FRONTAL LOBE – The most anterior portion of the cerebral cortex.
PARIETAL LOBE – Lying between the frontal and occipital lobes.
TEMPORAL LOBE – Lateral region of cortex in each cerebral hemisphere.
OCCIPITAL LOBE – Covers much of the posterior part of each cerebral hemisphere.
- The four major cortical regions of each cerebral hemisphere.
SYLVAN FISSURE (or lateral sulcus) – A deep fissure that demarcates the temporal lobe. Divides the temporal lobe from other regions of the hemisphere.
CENTRAL SUCLUS – Dividing the frontal and parietal lobes. A fissure that divides the frontal lobe from the parietal lobe.
CORTEX – The seat of complex cognition.
- The four lobes of the cortex are continually communicating and collaborating in order to produce the seamless control of complex behavior that distinguishes us as individuals.
CORPUS CALLOSUM – Hundreds of millions of axons connect the left and right hemispheres via the corpus callosum, allowing the brain to act as a single entity during complex processing.
POSTCENTRAL GYRUS – The sense of touch is mediated by a strip of parietal cortex just behind the central sulcus called the postcentral gyrus.
- Somatosensory cortex.
PRECENTRAL GYRUS – Strip of frontal cortex, just anterior to (in front of) the central sulcus, that is crucial for motor control.
- Primary motor cortex.
- Both gyri exhibitSOMATOTOPIC ORGANIZATION which means that they precisely map the various parts of the contralateral side of the body.
Development of Subdivisions Within the Brain
Development of Subdivisions Within the Brain:
NEURAL TUBE – An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain.
FOREBRAIN – The frontal division the neural tube, containing the cerebral hemispheres, the thalamus, and the hypothalamus.
MIDBRAIN – The middle division of the brain.
HINDBRAIN – The rear division of the brain, which in the mature vertebrate contains the cerebellum, pons, and medulla.
TELENCEPHALON – The anterior part of the fetal forebrain, which will become the cerebral hemispheres in the adult brain.
DIENCEPHALON – The posterior part of the fetal forebrain, which will become the thalamus and hypothalamus in the adult brain.
BRAINSTEM – The region of the brain that consists of the midbrain, the pons, and the medulla.
Brain Shows Regional Specialization of Functions
Brain Shows Regional Specialization of Functions:
Bilaterally Symmetrical – Our bodies have mirror-image left and right sides.
- The brain is no exception, and almost all the structures of the brain also come in twos.
- Each side of the brain generally controls the contralateral side of the body. The right side of the brain thus controls movement of the left side of the body and receives left-sided sensory information.
CEREBRAL CORTEX:
- Cortical neurons make up six distinct layers.
PYRAMIDAL CELL – The most prominent kind of neuron in the cerebral cortex. A type of large nerve cell that has a roughly pyramid-shaped cell body and is found in the cerebral cortex.
CORTICAL COLUMNS – One of the vertical columns that constitute the basic organization of the cerebral cortex. In some regions of the cerebral cortex, neurons are organized into regular columns, perpendicular to the layers, that seem to serve as information-processing units.
- Extend through the entire thickness of the cortex, from the white matter to the surface.
- Within each column, most of the synaptic interconnections of neurons are vertical, although there are some horizontal connections as well.
NUCLEI HIDDEN BENEATH THE CEREBRAL CORTEX:
- Within the cerebral hemispheres are several large gray matter structures.
- One prominent cluster—
BASAL GANGLIA – A group of forebrain nuclei, including the caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres. Plays a critical role in the control of movement.
LIMBIC SYSTEM – That is involved in emotion and learning.
AMYGDALA – Is a limbic structure involved in emotional regulation. A group of nuclei in the medial anterior part of the temporal lobe.
HIPPOCAMPUS – A medial temporal lobe structure that is important for learning and memory.
FORNIX – Important for learning and memory. ber tract that extends from the hippocampus to the mammillary body.
CINGULATE GYRUS – A strip of cortex atop the corpus callosum in each hemisphere, is implicated in many cognitive functions, including the direction of attention.
OLFACTORY BULB – Processes the sense of smell.
OTHER LIMBIC STRUCTRES – Help to govern motivated behaviors, like sex and aggression, and to regulate the hormonal systems.
THALAMUS – The thalamus is the brain’s traffic cop, directing virtually all incoming sensory information to the appropriate regions of the cortex.
HYPOTHALAMUS (the latter means simply “under thalamus”).– Has a much different role: it is packed with discrete nuclei involved in many vital functions, such as hunger, thirst, temperature regulation, sex, and many more.
Midbrain Has Sensory and Motor Components
Midbrain Has Sensory and Motor Components:
TECTUM – The dorsal portion of the midbrain, consisting of the inferior and superior colliculi. Specific roles in sensory processing.
SUPERIOR COLLICULI – Specific roles in visual processing.
INFERIOR COLLICULI – Process information about sound.
TEGMENTUM – The main body of the midbrain. Containing the substantia nigra, periaqueductal gray, part of the reticular formation, and multiple fiber tracts.
SUBSTANTIA NIGRA – Is in many ways a part of the basal ganglia, and loss of its neurons leads to Parkinson’s disease.
- Which normally release the neurotransmitter dopamine within the forebrain.
PERLAQUEDUCTAL GRAY – Midbrain structure implicated in the perception of pain.
RETICULAR FORMATION – A loose collection of neurons that are important in a variety of behaviors, including sleep and arousal.
Brainstem Controls Vital Body Functions:
CEREBELLUM – A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement and in some forms of learning. cerebellum has long been known to be crucial for motor coordination and control, also participates in certain aspects of cognition, including learning.
PONS – The portion of the brainstem that connects the midbrain to the medulla. contains many nerve fibers and important motor control and sensory nuclei.
MEDULLA – Marks the transition from the brain to the spinal cord. In addition to conveying all of the major motor and sensory fibers to and from the body, the medulla contains nuclei that drive such essential processes as respiration and heart rate.
Behaviors and Cognitive Processes Depend on Networks of Brain Regions:
- In order to understand the neural origins of our most complex behaviors and experiences—thought, language, music—it will be necessary to understand how different brain regions with distinct functions collaborate in larger-scale networks
- Cortical regions communicate with one another via tracts of axons looping through the underlying white matter.
Specialized Support Systems Protect and Nourish the Brain
Specialized Support Systems Protect and Nourish the Brain:
- The brain is equipped with systems to protect and cushion it and to provide a continual source of energy, nutrients, and important chemicals.
Brain Floats Within Layers of Membranes:
MENINGES – Brain and spinal cord are swaddled by three protective membranes called meninges The three protective membranes—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord.
- DURA MATER – Between a tough outer sheet called the dura mater.
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PIA MATER – Delicate. The innermost of the three meninges that surround the brain and spinal cord.
- That adheres tightly to the surface of the brain, a webby substance called the arachnoid.
- ARACHNOID – The thin covering (one of the three meninges) of the brain that lies between the dura mater and the pia mater. Creates a reservoir called the subarachnoid space that suspends the brain in a bath of a watery liquid – cerebrospinal fluid
- CEREBROSPINAL FLUID (CSF) – The fluid that fills the cerebral ventricles.
- MENINGITIS – The meninges can become inflamed by infections. An acute inflammation of the meninges, usually caused by a viral or bacterial infection.
- MENINGIOMAS – A noninvasive tumor of the meninges.
BRAIN RELIES ON TWO FLUIDS FOR SURVIVAL:
- The brain essentially floats in cerebrospinal fluid within the subarachnoid space, cushioning it from minor blows to the head.
CEREBROSPINAL FLUID (CSF) – has additional important roles, passing into the substance of the brain, conveying nutrients and signaling chemicals, and picking up waste matter for later clearance.
- Inside the brain is a series of chambers called the cerebral ventricles, which are filled with CSF:
VENTRICULAR SYSTEM – A system of fluid-filled cavities inside the brain. These chambers comprise the ventricular system.
LATERAL VENTRICLE – Each hemisphere of the brain contains a lateral ventricle extending into all four lobes of the hemisphere.
- CHOROID PLEXUS – lateral ventricles are lined with a specialized membrane called the choroid plexus, which produces CSF by filtering blood.
THIRD VENTRICLE – The midline ventricle that conducts cerebrospinal fluid from the lateral ventricles to the fourth ventricle.
FOURTH VENTRICLE – The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord.
HYDROCEPHALUS – A ballooning of the ventricles, at the expense of the surrounding brain, which may occur when the circulation of CSF is blocked.
GLYMPHATIC SYSTEM – The name reflects the involvement of glial cells. A lymphatic system in the brain that participates in removal of wastes and the movement of nutrients and signaling compounds.
Glymphatic drainage, which occurs primarily during sleep, helps clear debris and wastes from the brain, including proteins that have been implicated in Alzheimer’s disease.
- The second crucial fluid for the brain is, of course, blood. Without a lavish supply of oxygen- and nutrient-rich blood, the tissue of the brain would swiftly die.
- That’s because brain tissue is unusually needy: it accounts for only 2% of the average human body but consumes more than 20% of the body’s energy at rest.
CEREBRAL ARTERIES – Arteries that supply the cortex.
BLOOD-BRAIN BARRIER – In contrast to capillaries in the rest of the body, capillaries in the brain are highly resistant to the passage of large molecules across their walls and into neighboring neurons.
- Probably evolved to help protect the brain from infections and blood-borne toxins, but it also makes the delivery of drugs to the brain more difficult.
NOTE–Figure 1.17 is attached on the next card #14
Stroke
STROKE – a situation in which a clot, a narrowing, or a rupture interrupts the supply of blood to a particular brain region, causing the affected region to stop functioning or die
Three Types of Study Designs Probe Brain-Behavior Relationships
Three Types of Study Designs Probe Brain-Behavior Relationships:
SOMATIC INTERVENTION– we alter a structure or function of the brain or body to see how this alteration changes behavior.
- The physical alteration is an independent variable (a general term used to describe the manipulated aspect of any experiment), and the behavioral effect is the dependent variable (a general term used to describe the measured consequence of an experimental manipulation).
- Some examples of somatic intervention experiments include (1) administering a hormone to some animals, but not others, and comparing their sexual behavior; (2) electrically stimulating a specific brain region and measuring alterations in movement; and (3) destroying a specific region in the brain and observing subsequent changes in sleep patterns.
WITHIN -PARTICIPANTS EXPERIMENT – The control group is simply the same individuals, tested before the somatic intervention occurs.
BETWEEN-PARTICIPANTS EXPERIMENT – The experimental group of individuals is compared with a different group of individuals who are treated identically in every way except that they don’t receive the somatic intervention.
- The approach opposite to somatic intervention is behavioral intervention.
BEHAVIORAL INTERVENTION – In this approach the scientist alters or controls the behavior of an organism and looks for resulting changes in body structure or function. An approach to finding relations between body variables and behavioral variables that involves intervening in the behavior of an organism and looking for resultant changes in body structure or function.
- Here, behavior is the independent variable, and change in the body is the dependent variable.
- A few examples include (1) allowing adults of each sex to interact and then measuring their hormone levels, (2) having a person perform a cognitive task while in a brain scanner and then measuring changes in activity in specific regions of the brain, and (3) training an animal to fear a previously neutral stimulus and then observing electrical changes in the brain that may encode the newly learned association.
CORRELATION – Measures how closely changes in one variable are associated with changes in another variable.
- Even though it can’t establish causality, correlational research can help researchers identify which things are linked, directly or indirectly, and thus it helps us to develop hypotheses that can be tested experimentally using behavioral and somatic interventions.
