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Self Assessment Chapter 12 part 2 • ___________– important functional brain system, includes limbic lobe (region of medial cerebrum), hippocampus, amygdala, and pathways; connect each of these regions of gray matter with rest of brain (Figure 12.9) • Found only within mammalian brains • Involved in memory, learning, emotion, and behavior • When you are nervous and have “butterflies in your stomach” or are scared and have a racing heart, that reaction is partially a product of your limbic system. © 2016 Pearson Education, Inc. The Cerebrum-Limbic System • Limbic system – important functional brain system, includes limbic lobe (region of medial cerebrum), hippocampus, amygdala, and pathways; connect each of these regions of gray matter with rest of brain (Figure 12.9) • Found only within mammalian brains • Involved in memory, learning, emotion, and behavior • When you are nervous and have “butterflies in your stomach” or are scared and have a racing heart, that reaction is partially a product of your limbic system. © 2016 Pearson Education, Inc. The Cerebrum-Limbic System • Limbic system (continued): • ___________and associated structures form a ring on medial side of cerebral hemisphere; contain two main gyri: cingulate gyrus and parahippocampal gyrus • ___________– in temporal lobe; connected to a prominent C-shaped ring of white matter (fornix) which is its main output tract; involved in memory and learning • ___________– anterior to hippocampus; involved in behavior and expression of emotion, especially fear © 2016 Pearson Education, Inc. The Cerebrum-Limbic System • Limbic system (continued): • Limbic lobe and associated structures form a ring on medial side of cerebral hemisphere; contain two main gyri: cingulate gyrus and parahippocampal gyrus • Hippocampus – in temporal lobe; connected to a prominent C-shaped ring of white matter (fornix) which is its main output tract; involved in memory and learning • Amygdala – anterior to hippocampus; involved in behavior and expression of emotion, especially fear © 2016 Pearson Education, Inc. The Diencephalon Diencephalon – at physical center of brain; composed of four components, each with its own nuclei that receive specific input and send output to other brain regions (Figure 12.10): • ___________ • ___________ • ___________ • ___________ © 2016 Pearson Education, Inc. The Diencephalon Diencephalon – at physical center of brain; composed of four components, each with its own nuclei that receive specific input and send output to other brain regions (Figure 12.10): • Thalamus • Hypothalamus • Epithalamus • Subthalamus © 2016 Pearson Education, Inc. The Diencephalon • ___________– main entry route of sensory data into cerebral cortex (Figure 12.10a, b) • Consists of two egg-shaped regions of gray matter; make up about 80% of diencephalon • Third ventricle is found between these two regions • Thalamic nuclei receive afferent fibers from many other regions of nervous system excluding information about the sense of smell © 2016 Pearson Education, Inc. The Diencephalon • Thalamus – main entry route of sensory data into cerebral cortex (Figure 12.10a, b) • Consists of two egg-shaped regions of gray matter; make up about 80% of diencephalon • Third ventricle is found between these two regions • Thalamic nuclei receive afferent fibers from many other regions of nervous system excluding information about the sense of smell © 2016 Pearson Education, Inc. The Diencephalon • Thalamus (continued): • Regulates cortical activity by controlling which input should continue to cerebral cortex • Each half of thalamus has three main groups of nuclei separated by thin layers of white matter • Specific nuclei function as ___________that receive input, integrate information, then send information to specific motor or sensory areas in cerebral cortex © 2016 Pearson Education, Inc. The Diencephalon • Thalamus (continued): • Regulates cortical activity by controlling which input should continue to cerebral cortex • Each half of thalamus has three main groups of nuclei separated by thin layers of white matter • Specific nuclei function as relay stations that receive input, integrate information, then send information to specific motor or sensory areas in cerebral cortex © 2016 Pearson Education, Inc. The Diencephalon • ___________– collection of nuclei anterior and inferior to larger thalamus • Neurons perform several vital functions critical to survival; include regulation of autonomic nervous system, sleep/wake cycle, thirst and hunger, and body temperature © 2016 Pearson Education, Inc. The Diencephalon • Hypothalamus – collection of nuclei anterior and inferior to larger thalamus • Neurons perform several vital functions critical to survival; include regulation of autonomic nervous system, sleep/wake cycle, thirst and hunger, and body temperature © 2016 Pearson Education, Inc. The Diencephalon • Hypothalamus (continued): • Inferior hypothalamus – anatomically and functionally linked to pituitary gland by an extension called infundibulum; hypothalamic tissue makes up posterior portion of this endocrine gland • Hypothalamus secretes a number of different releasing and inhibiting hormones; affect function of pituitary gland; in turn, pituitary gland secretes hormones that affect activities of other endocrine glands throughout body © 2016 Pearson Education, Inc. The Diencephalon • Hypothalamus (continued): • Antidiuretic hormone and oxytocin, hypothalamic hormones that do not affect pituitary gland, have their effect on water balance and stimulation of uterine contraction during childbirth, respectively • Input to hypothalamus arrives from many sources including cortex and basal nuclei © 2016 Pearson Education, Inc. ___________– makes up posterior and inferior portion of brain; functionally connected with cerebral cortex, basal nuclei, brainstem, and spinal cord; interactions between these regions together coordinate movement (Figure 12.11) • Anatomically, divided into two cerebellar hemispheres connected by structure called vermis (Figure 12.11a) • Ridges called folia cover exterior cerebellar surface; separated by shallow sulci; increases surface area of region © 2016 Pearson Education, Inc. Cerebellum Cerebellum – makes up posterior and inferior portion of brain; functionally connected with cerebral cortex, basal nuclei, brainstem, and spinal cord; interactions between these regions together coordinate movement (Figure 12.11) • Anatomically, divided into two cerebellar hemispheres connected by structure called vermis (Figure 12.11a) • Ridges called folia cover exterior cerebellar surface; separated by shallow sulci; increases surface area of region © 2016 Pearson Education, Inc. The Brainstem Figure 12.12a Midsagittal section of the brain showing the brainstem. © 2016 Pearson Education, Inc. The Brainstem • ___________ • Includes following structures: • Superior and inferior colliculi, protrude from posterior surface of brainstem; two paired projections that form roof of midbrain (tectum); involved in visual (reflex centers that control head and eye movements) and auditory functions respectively; project to thalamus • Descending tracts – white matter tracts that originate in cerebrum and form anteriormost portion of midbrain; called crus cerebri © 2016 Pearson Education, Inc. The Brainstem • Midbrain (continued): • Includes following structures: • Superior and inferior colliculi, protrude from posterior surface of brainstem; two paired projections that form roof of midbrain (tectum); involved in visual (reflex centers that control head and eye movements) and auditory functions respectively; project to thalamus • Descending tracts – white matter tracts that originate in cerebrum and form anteriormost portion of midbrain; called crus cerebri © 2016 Pearson Education, Inc. The Brainstem • ___________(continued): • Pontine tegmentum – surrounded by middle cerebellar peduncles • Pontine nuclei have many roles including: regulation of movement, breathing, (assists the medulla in maintaining the normal rhythms of breathing) reflexes, and complex functions associated with sleep and arousal © 2016 Pearson Education, Inc. The Brainstem • Pons (continued): • Pontine tegmentum – surrounded by middle cerebellar peduncles • Pontine nuclei have many roles including: regulation of movement, breathing, (assists the medulla in maintaining the normal rhythms of breathing) reflexes, and complex functions associated with sleep and arousal © 2016 Pearson Education, Inc. The Brainstem • Medulla oblongata (continued): • Right and left corticospinal fibers ___________ (crossover) within pyramids; motor fibers originating from right side of cerebral cortex descend through left side of spinal cord and vice versa • Posterior columns – paired tracts of white matter found on medulla’s posterior surface; carry sensory information from spinal cord to nucleus gracilis and nucleus cuneatus © 2016 Pearson Education, Inc. The Brainstem • Medulla oblongata (continued): • Right and left corticospinal fibers decussate (crossover) within pyramids; motor fibers originating from right side of cerebral cortex descend through left side of spinal cord and vice versa • Posterior columns – paired tracts of white matter found on medulla’s posterior surface; carry sensory information from spinal cord to nucleus gracilis and nucleus cuneatus © 2016 Pearson Education, Inc. The Brainstem • Autonomic Reflex Center Functions of the ___________ • Cardiovascular center – adjusts the force and rate of heart contractions and changes blood vessel diameter. • Respiratory Centers – these generate the respiratory rhythm and with pontine centers control the rate and depth of breathing • Various other centers – regulate vomiting, hiccuping, swallowing, coughing, and sneezing. © 2016 Pearson Education, Inc. The Brainstem • Autonomic Reflex Center Functions of the Medulla • Cardiovascular center – adjusts the force and rate of heart contractions and changes blood vessel diameter. • Respiratory Centers – these generate the respiratory rhythm and with pontine centers control the rate and depth of breathing • Various other centers – regulate vomiting, hiccuping, swallowing, coughing, and sneezing. © 2016 Pearson Education, Inc. The Brainstem • ___________(continued): • Central nuclei (center of reticular formation) function in sleep, pain transmission, and mood • Nuclei surrounding central nuclei serve motor functions for both skeletal muscles and autonomic nervous system • Other nuclei are instrumental in homeostasis of breathing and blood pressure • Lateral nuclei play a role in sensation and in alertness and activity levels of cerebral cortex © 2016 Pearson Education, Inc. The Brainstem • Reticular formation (continued): • Central nuclei (center of reticular formation) function in sleep, pain transmission, and mood • Nuclei surrounding central nuclei serve motor functions for both skeletal muscles and autonomic nervous system • Other nuclei are instrumental in homeostasis of breathing and blood pressure • Lateral nuclei play a role in sensation and in alertness and activity levels of cerebral cortex © 2016 Pearson Education, Inc. Brain Protection Three features within protective shell of skull provide additional shelter for delicate brain tissue: • ___________– three layers of membranes that surround brain • ___________– fluid that bathes brain and fills cavities • – prevents many substances from entering brain and its cells from blood © 2016 Pearson Education, Inc. Brain Protection Three features within protective shell of skull provide additional shelter for delicate brain tissue: • Cranial meninges – three layers of membranes that surround brain • Cerebrospinal fluid (CSF) – fluid that bathes brain and fills cavities • Blood-brain barrier – prevents many substances from entering brain and its cells from blood © 2016 Pearson Education, Inc. Brain Protection • Cranial meninges – composed of three protective membrane layers of mostly dense irregular collagenous tissue • Structural arrangement from superficial to deep: epidural space, ___________mater, subdural space, ___________mater, subarachnoid space, and ___________mater (Figure 12.18) © 2016 Pearson Education, Inc. Brain Protection • Cranial meninges – composed of three protective membrane layers of mostly dense irregular collagenous tissue • Structural arrangement from superficial to deep: epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, and pia mater (Figure 12.18) © 2016 Pearson Education, Inc. The Ventricles and Cerebrospinal Fluid Figure 12.19 Ventricles of the brain. © 2016 Pearson Education, Inc. The Ventricles and Cerebrospinal Fluid • Cerebrospinal fluid (CSF) – clear, colorless liquid similar in composition to blood plasma; protects brain in following ways: • Cushions brain and maintains a constant temperature within cranial cavity • Removes wastes and increases buoyancy of brain; keeps brain from collapsing under its own weight © 2016 Pearson Education, Inc. The Ventricles and Cerebrospinal Fluid • ___________– where majority of CSF is manufactured; found in each of four ventricles where blood vessels come into direct contact with ependymal cells (also produce some CSF themselves) • Fenestrated capillaries have gaps between endothelial cells; allow fluids and electrolytes to exit from blood plasma to enter extracellular fluid (ECF) © 2016 Pearson Education, Inc. The Ventricles and Cerebrospinal Fluid • Choroid plexuses – where majority of CSF is manufactured; found in each of four ventricles where blood vessels come into direct contact with ependymal cells (also produce some CSF themselves) • Fenestrated capillaries have gaps between endothelial cells; allow fluids and electrolytes to exit from blood plasma to enter extracellular fluid (ECF) © 2016 Pearson Education, Inc. The Ventricles and Cerebrospinal Fluid • Pathway for formation, circulation, and reabsorption of CSF (Figure 12.20): • Fluid and electrolytes leak out of capillaries of choroid plexuses into ECF of ventricles • Taken up into ependymal cells; then secreted into ventricles as CSF • Circulated through and around brain and spinal cord in subarachnoid space; assisted by movement of ependymal cell cilia • Some CSF is reabsorbed into venous blood in dural sinuses via arachnoid granulations © 2016 Pearson Education, Inc. The Blood-Brain Barrier ___________– protective safeguard that separates CSF and brain ECF from chemicals and disease-causing organisms sometimes found in blood plasma (Figure 12.21) • Consists mainly of simple squamous epithelial cells (endothelial cells) of blood capillaries, their basal laminae, and astrocytes © 2016 Pearson Education, Inc. The Blood-Brain Barrier Blood-brain barrier – protective safeguard that separates CSF and brain ECF from chemicals and disease-causing organisms sometimes found in blood plasma (Figure 12.21) • Consists mainly of simple squamous epithelial cells (endothelial cells) of blood capillaries, their basal laminae, and astrocytes © 2016 Pearson Education, Inc. The Blood-Brain Barrier Figure 12.21 The blood-brain barrier. © 2016 Pearson Education, Inc. • ___________– composed primarily of nervous tissue; responsible for both relaying and processing information; less anatomically complex than brain but still vitally important to normal nervous system function; two primary roles: • Serves as a relay station and as an intermediate point between body and brain; only means by which brain can interact with body below head and neck • Processing station for some less complex activities such as spinal reflexes; do not require higher level processing © 2016 Pearson Education, Inc. The Spinal Cord • Spinal cord – composed primarily of nervous tissue; responsible for both relaying and processing information; less anatomically complex than brain but still vitally important to normal nervous system function; two primary roles: • Serves as a relay station and as an intermediate point between body and brain; only means by which brain can interact with body below head and neck • Processing station for some less complex activities such as spinal reflexes; do not require higher level processing © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy Butterfly-shaped spinal gray matter is surrounded by tracts of white matter; following features are seen on cross section of spinal cord (Figures 12.24, 12.25): • ___________– filled with CSF; seen in center of spinal cord; surrounded by two thin strips of gray matter (gray commissure); connects each “butterfly” wing © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy Butterfly-shaped spinal gray matter is surrounded by tracts of white matter; following features are seen on cross section of spinal cord (Figures 12.24, 12.25): • Central canal – filled with CSF; seen in center of spinal cord; surrounded by two thin strips of gray matter (gray commissure); connects each “butterfly” wing © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy • Spinal gray matter makes up three distinct regions found within spinal cord; houses neurons with specific functions and includes (Figure 12.24): • ___________makes up anterior wing of gray matter and gives rise to anterior motor nerve roots; neuron cell bodies found in this region are involved in somatic motor functions (skeletal muscle contraction) © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy • Spinal gray matter makes up three distinct regions found within spinal cord; houses neurons with specific functions and includes (Figure 12.24): • Anterior horn (ventral horn) makes up anterior wing of gray matter and gives rise to anterior motor nerve roots; neuron cell bodies found in this region are involved in somatic motor functions (skeletal muscle contraction) © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy • Spinal gray matter (continued): • ___________(or dorsal horn) makes up posterior wing of gray matter and gives rise to posterior sensory nerve roots; neuron cell bodies found in this region are involved in processing incoming somatic and visceral sensory information • ___________found only in spinal cord between first thoracic vertebra and lumbar region; contains cell bodies of neurons involved in control of viscera via autonomic nervous system © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy • Spinal gray matter (continued): • Posterior horn (or dorsal horn) makes up posterior wing of gray matter and gives rise to posterior sensory nerve roots; neuron cell bodies found in this region are involved in processing incoming somatic and visceral sensory information • Lateral horn, found only in spinal cord between first thoracic vertebra and lumbar region; contains cell bodies of neurons involved in control of viscera via autonomic nervous system © 2016 Pearson Education, Inc. Internal Spinal Cord Anatomy Figure 12.24 Overview of internal spinal cord structure and function. © 2016 Pearson Education, Inc. Sensory Stimuli • Sensory stimuli (continued): • When CNS has received all different sensory inputs, it integrates them into a single perception (a conscious awareness of sensation) • Sensations can be grouped into two basic types: • Special senses – detected by special sense organs and include vision, hearing, equilibrium, smell, and taste • General senses – detected by sensory neurons in skin, muscles, or walls of organs; can be further subdivided into general somatic senses that involve skin, muscles, and joints and general visceral senses that involve internal organs © 2016 Pearson Education, Inc. General Somatic Senses • Basic pathway consists of following: • ___________detects initial stimulus in PNS; axon of this neuron then synapses on a second-order neuron • ___________– interneuron located in posterior horn of spinal cord or in brainstem; relays stimulus to a third-order neuron • ___________– an interneuron found in thalamus; delivers impulse to cerebral cortex © 2016 Pearson Education, Inc. General Somatic Senses • Basic pathway consists of following: • First-order neuron detects initial stimulus in PNS; axon of this neuron then synapses on a second-order neuron • Second-order neuron – interneuron located in posterior horn of spinal cord or in brainstem; relays stimulus to a third-order neuron • Third-order neuron – an interneuron found in thalamus; delivers impulse to cerebral cortex © 2016 Pearson Education, Inc. General Somatic Senses © 2016 Pearson Education, Inc. General Somatic Senses Figure 12.26 Ascending (sensory) pathways: the posterior column/medial lemniscal 2016 Pearson systems in the right and left sides of© the body. Education, Inc. General Somatic Senses Figure 12.27 Ascending (sensory) pathways: the right and left spinothalamic tracts (part of the anterolateral system). © 2016 Pearson Education, Inc. General Somatic Senses • Role of Cerebral Cortex in Sensation, S1 and Somatotopy: • Thalamus relays most incoming information to ___________cortex (____) in postcentral gyrus • Each part of body is represented by a specific region of S1, a type of organization called ___________ (Figure 12.28) © 2016 Pearson Education, Inc. General Somatic Senses • Role of Cerebral Cortex in Sensation, S1 and Somatotopy: • Thalamus relays most incoming information to primary somatosensory cortex (S1) in postcentral gyrus • Each part of body is represented by a specific region of S1, a type of organization called somatotopy (Figure 12.28) © 2016 Pearson Education, Inc. General Somatic Senses Figure 12.28 Representations of the primary somatosensory cortex. © 2016 Pearson Education, Inc. General Somatic Senses • Role of the Cerebral Cortex in Sensation – Processing of Pain Stimuli: perception of pain stimuli is called nociception • Thalamus relays pain stimuli to several brain regions including S1 and S2 where sensory discrimination (localization, intensity, and quality) is perceived and analyzed • Also sent to basal nuclei, regions of limbic system, hypothalamus, and prefrontal cortex, where emotional and behavioral aspects of pain are processed © 2016 Pearson Education, Inc. Voluntary Movement 1. 2. 3. Upper motor neurons with cell bodies in motor area of cerebral cortex (most) or brainstem (some) – axons descend through cerebral white matter to brainstem and spinal cord; synapse with local interneurons Local interneurons – pass messages from upper motor neurons to neighboring lower motor neurons Cell bodies of lower motor neurons reside in anterior horn of spinal gray matter; axons (components of PNS) exit CNS to innervate skeletal muscles © 2016 Pearson Education, Inc. Motor Pathways from Brain through Spinal Cord Figure 12.29 Descending (motor) pathways: the right and left lateral corticospinal tracts. © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement Even simple movements require simultaneous firing of countless neurons as part of a selected group of actions called a ___________ Execution of any motor program requires firing of neurons in motor association areas, firing of upper motor neurons, and input from basal nuclei, cerebellum, spinal cord, and multimodal association areas (prefrontal cortex and various sensory areas) • Firing of lower motor neurons in PNS is necessary to complete task © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement Even simple movements require simultaneous firing of countless neurons as part of a selected group of actions called a motor program • Execution of any motor program requires firing of neurons in motor association areas, firing of upper motor neurons, and input from basal nuclei, cerebellum, spinal cord, and multimodal association areas (prefrontal cortex and various sensory areas) • Firing of lower motor neurons in PNS is necessary to complete task © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement • Role of Basal Nuclei (continued): • Damage to any component of basal nuclei system results in a ___________disorder; two main forms: • Inability to initiate voluntary movement, making simple activities such as walking or talking difficult • Inability to inhibit inappropriate, involuntary movements; some of which are mild (throat clearing or blinking); others may be severe enough to cause disability © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement • Role of Basal Nuclei (continued): • Damage to any component of basal nuclei system results in a movement disorder; two main forms: • Inability to initiate voluntary movement, making simple activities such as walking or talking difficult • Inability to inhibit inappropriate, involuntary movements; some of which are mild (throat clearing or blinking); others may be severe enough to cause disability © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement Figure 12.31 Role of the basal nuclei in voluntary movement. © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement • Role of the Cerebellum (continued): • Cerebellum receives input from three sources simultaneously: • motor areas of cerebral cortex via upper motor neurons • vestibular nuclei of pons • ascending sensory tracts from spinal cord © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement • Like basal nuclei, cerebellum affects movement by modifying activity of upper motor neurons; cerebellum does not have direct connections with lower motor neurons • Damage to cerebellum makes fluid, well-coordinated movements nearly impossible; movements become jerky and inaccurate; called ___________ © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement • Like basal nuclei, cerebellum affects movement by modifying activity of upper motor neurons; cerebellum does not have direct connections with lower motor neurons • Damage to cerebellum makes fluid, well-coordinated movements nearly impossible; movements become jerky and inaccurate; called cerebellar ataxia © 2016 Pearson Education, Inc. Role of Brain in Voluntary Movement Figure 12.32 Role of the cerebellum in voluntary movement. © 2016 Pearson Education, Inc. The Big Picture of CNS Control of Voluntary Movement Figure 12.33 The Big Picture of CNS© Control of Voluntary Movement. 2016 Pearson Education, Inc. Role of CNS in Maintenance of Homeostasis • Two structures of CNS are concerned directly with maintenance of homeostasis: • ___________– controls functions of many internal organs as well as aspects of behavior • ___________– closely associated (anatomically and functionally) with pituitary gland; reflects close relationship between these vital systems • Reticular formation and hypothalamus have many interconnections; enable them to coordinate many homeostatic functions © 2016 Pearson Education, Inc. Role of CNS in Maintenance of Homeostasis • Two structures of CNS are concerned directly with maintenance of homeostasis: • Reticular formation – controls functions of many internal organs as well as aspects of behavior • Hypothalamus – closely associated (anatomically and functionally) with pituitary gland; reflects close relationship between these vital systems • Reticular formation and hypothalamus have many interconnections; enable them to coordinate many homeostatic functions © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Maintenance of vital functions (heart pumping, blood pressure, and digestion) is largely controlled by ___________,regulates function of body’s viscera • Although _____is a component of PNS it is controlled by components of CNS, mainly hypothalamus © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Maintenance of vital functions (heart pumping, blood pressure, and digestion) is largely controlled by autonomic nervous system (ANS); regulates function of body’s viscera • Although ANS is a component of PNS it is controlled by components of CNS, mainly hypothalamus © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Although ANS is a component of PNS it is controlled by components of CNS, mainly hypothalamus (continued): • Hypothalamus receives sensory input from viscera, components of the limbic system, and the cerebral cortex • Allows hypothalamus to respond to both normal physiological changes and emotional changes and to adjust ANS output to maintain homeostasis © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Hypothalamus maintains homeostasis largely by relaying instructions to nuclei in reticular formation of medulla; include following centers: • Neurons of vasopressor center – located in anterolateral medulla; when stimulated by hypothalamus, center increases rate and force of cardiac contractions and causes blood vessels to narrow; increases blood pressure © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Hypothalamus maintains homeostasis largely by relaying instructions to nuclei in reticular formation of medulla; include following centers (continued): • Vasodepressor center – located inferior and medial to vasopressor center; decreases rate and force of heart contractions and opens blood vessels; all three effects decrease blood pressure • Other centers: many nuclei in reticular formation participate in regulation of digestive processes and control of urination © 2016 Pearson Education, Inc. Homeostasis of Vital Functions • Respiration is one of few vital functions not under ANS control • Rate and depth of breathing are regulated by group of neurons in anterior medullary reticular formation • Several factors influence neuron firing rates: input from cerebral cortex, limbic system, hypothalamus, certain sensory receptors, and nuclei in pons © 2016 Pearson Education, Inc. Body Temperature Homeostasis • Hypothalamus regulates body temperature • Acts as body’s thermostat; creates a set point for normal body temperature, about 37 C or 98.6 F • Input is received from temperature-sensitive neurons located in several places (skin and areas deeper in body) and from neurons in hypothalamus itself © 2016 Pearson Education, Inc. Body Temperature Homeostasis • Hypothalamus regulates body temperature (continued): • When body temperature increases above set point, a negative feedback loop is initiated whereby certain hypothalamic nuclei induce changes that cool body • When body temperature decreases below set point, a different feedback loop is initiated that conserves heat • Both are examples of Feedback Loops Core Principle • Fever ensues when body temperature set point is temporarily set higher than normal © 2016 Pearson Education, Inc. Regulation of Feeding • Hypothalamus also regulates feeding • Stimulation of certain hypothalamic nuclei induces hunger and feeding behaviors; indirectly preserves homeostasis of glucose • Thought to be related to secretion of neurotransmitters called orexins © 2016 Pearson Education, Inc. Sleep and Wakefulness • Sleep (continued): • Circadian Rhythms and Biological “Clock”: Human sleep follows a ___________We spend a period of cycle awake and remainder asleep • Rhythm is controlled by hypothalamus; causes changes in level of wakefulness in response to day and night cycles © 2016 Pearson Education, Inc. Sleep and Wakefulness • Sleep (continued): • Circadian Rhythms and Biological “Clock”: Human sleep follows a circadian rhythm • We spend a period of cycle awake and remainder asleep • Rhythm is controlled by hypothalamus; causes changes in level of wakefulness in response to day and night cycles © 2016 Pearson Education, Inc. Sleep and Wakefulness Figure 12.34 The process of falling ©asleep. 2016 Pearson Education, Inc. Sleep and Wakefulness • Brain Waves and Stages of Sleep (continued): • State IV sleep is deepest stage with characteristic low- frequency, highamplitude delta waves; stages I–IV collectively is known as non-REM sleep or non-rapid eye movement sleep • ___________(rapid eye movement) lasts for 10–15 minutes and occurs after stage IV sleep; known for back and forth eye movements; stage where most dreaming occurs; REM waves resemble beta waves of wakefulness © 2016 Pearson Education, Inc. Sleep and Wakefulness • Brain Waves and Stages of Sleep (continued): • State IV sleep is deepest stage with characteristic low- frequency, highamplitude delta waves; stages I–IV collectively is known as non-REM sleep or non-rapid eye movement sleep • REM sleep (rapid eye movement) lasts for 10–15 minutes and occurs after stage IV sleep; known for back and forth eye movements; stage where most dreaming occurs; REM waves resemble beta waves of wakefulness © 2016 Pearson Education, Inc. Sleep and Wakefulness Figure 12.35 Stages of wakefulness©and sleep as shown by EEG patterns. 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • Altered consciousness can indicate serious problems with brain function; examples include: • ___________– diminished level of cortical activity; arousable with strong/painful stimuli; caused by infections, mental illnesses, and brain conditions (such as brain tumors) • ___________– unarousable unconsciousness; no purposeful responses to any stimuli (even pain); underlying defect is damage to reticular activating system or related component; prohibits normal arousal of cerebral cortex © 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • Altered consciousness can indicate serious problems with brain function; examples include: • Stupor – diminished level of cortical activity; arousable with strong/painful stimuli; caused by infections, mental illnesses, and brain conditions (such as brain tumors) • Coma – unarousable unconsciousness; no purposeful responses to any stimuli (even pain); underlying defect is damage to reticular activating system or related component; prohibits normal arousal of cerebral cortex © 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • Altered consciousness can indicate serious problems with brain function; examples include (continued): • ___________– some patients move from coma state to condition where they are awake but unaware because of damage to cerebral cortex; also lack voluntary movement • Sleep/wake cycles do occur; brainstem reflexes remain intact, leading to involuntary movements (head turning and grunt-like vocalizations) • Can be misinterpreted as meaningful but not mediated by cortex, thus do not imply conscious awareness © 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • Altered consciousness can indicate serious problems with brain function; examples include (continued): • Persistent vegetative state – some patients move from coma state to condition where they are awake but unaware because of damage to cerebral cortex; also lack voluntary movement • Sleep/wake cycles do occur; brainstem reflexes remain intact, leading to involuntary movements (head turning and grunt-like vocalizations) • Can be misinterpreted as meaningful but not mediated by cortex, thus do not imply conscious awareness © 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • People in altered states of consciousness may occasionally regain consciousness, depending on cause of state • ___________– most extreme state of altered consciousness; EEG shows no activity; brainstem reflexes are absent; cerebral blood flow and metabolism are reduced to zero; consciousness will not be regained © 2016 Pearson Education, Inc. States of Altered Consciousness Mimicking Sleep • People in altered states of consciousness may occasionally regain consciousness, depending on cause of state • Brain death – most extreme state of altered consciousness; EEG shows no activity; brainstem reflexes are absent; cerebral blood flow and metabolism are reduced to zero; consciousness will not be regained © 2016 Pearson Education, Inc. Cognition and Language • Cognition – collective term for diverse group of tasks; performed by association areas of cerebral cortex • Cognitive ___________– include processing and responding to complex external stimuli, recognizing related stimuli, processing internal stimuli, and planning appropriate responses to stimuli • Cognitive ___________– responsible for social and moral behavior, intelligence, thoughts, problem-solving skills, language, and personality © 2016 Pearson Education, Inc. Cognition and Language • Cognition – collective term for diverse group of tasks; performed by association areas of cerebral cortex • Cognitive functions – include processing and responding to complex external stimuli, recognizing related stimuli, processing internal stimuli, and planning appropriate responses to stimuli • Cognitive processes – responsible for social and moral behavior, intelligence, thoughts, problem-solving skills, language, and personality © 2016 Pearson Education, Inc. Cognition and Language • Localization of Cognitive Function – following areas and their functions are involved in cognition: • Parietal association cortex – responsible for spatial awareness and attention; allows us to focus on distinct aspects of a specific object and recognize position of object in space • Temporal association cortex – primarily responsible for recognizing stimuli, especially complex stimuli such as faces © 2016 Pearson Education, Inc. Cognition and Language • Localization of Cognitive Function (continued): • Prefrontal cortex – largest and most complex of association cortices • Responsible for majority of cognitive functions that make up a person’s “character” or “personality” • Gathers information from other association cortices and from other sensory and motor cortices and integrates information to create an awareness of “self” • Allows for planning and execution of behaviors appropriate for given circumstances © 2016 Pearson Education, Inc. Cognition and Language • Cerebral ___________– phenomenon in which many cognitive functions are unequally represented in right and left hemispheres • Represents a division of labor between hemispheres to maximize a limited amount of brain space • Following functions appear to be lateralized although this is not an absolute (next slide) © 2016 Pearson Education, Inc. Cognition and Language • Cerebral lateralization – phenomenon in which many cognitive functions are unequally represented in right and left hemispheres • Represents a division of labor between hemispheres to maximize a limited amount of brain space • Following functions appear to be lateralized although this is not an absolute (next slide) © 2016 Pearson Education, Inc. Cognition and Language • Multiple brain regions are required for communication but two multimodal association areas are critical (Figure 12.36): • ___________– in frontal lobe; responsible for production of language, including planning and ordering of words with proper grammar and syntax • ___________– in temporal lobe; responsible for understanding language and linking a word with its correct symbolic meaning • ___________– language deficit; occurs when either of these two critical areas is damaged © 2016 Pearson Education, Inc. Cognition and Language • Multiple brain regions are required for communication but two multimodal association areas are critical (Figure 12.36): • Broca’s area – in frontal lobe; responsible for production of language, including planning and ordering of words with proper grammar and syntax • Wernicke’s area – in temporal lobe; responsible for understanding language and linking a word with its correct symbolic meaning • Aphasia – language deficit; occurs when either of these two critical areas is damaged © 2016 Pearson Education, Inc. Learning and Memory • Two basic types of memory: ___________ (fact) memory – defined as memory of things that are readily available to consciousness; could in principle be expressed aloud (hence term “declarative”), and ___________memory (procedural or skills memory); includes skills and associations that are largely unconscious • Declarative examples – phone number, a quote, or pathway of corticospinal tracts • Nondeclarative examples – how to enter phone number on a phone, how to move your mouth to speak, and how to read this chapter © 2016 Pearson Education, Inc. Learning and Memory • Two basic types of memory: declarative (fact) memory – defined as memory of things that are readily available to consciousness; could in principle be expressed aloud (hence term “declarative”), and nondeclarative memory (procedural or skills memory); includes skills and associations that are largely unconscious • Declarative examples – phone number, a quote, or pathway of corticospinal tracts • Nondeclarative examples – how to enter phone number on a phone, how to move your mouth to speak, and how to read this chapter © 2016 Pearson Education, Inc. Learning and Memory • Declarative and nondeclarative memory can be classified by length of time in which they are stored: • ___________– stored only for a few seconds; is critical for carrying out normal conversation, reading, and daily tasks • ___________ (working) memory – stored for several minutes; allows you to remember and manipulate information with a general behavioral goal in mind • ___________– a more permanent form of storage for days, weeks, or even a lifetime © 2016 Pearson Education, Inc. Learning and Memory • Declarative and nondeclarative memory can be classified by length of time in which they are stored: • Immediate memory – stored only for a few seconds; is critical for carrying out normal conversation, reading, and daily tasks • Short-term (working) memory – stored for several minutes; allows you to remember and manipulate information with a general behavioral goal in mind • Long-term memory – a more permanent form of storage for days, weeks, or even a lifetime © 2016 Pearson Education, Inc. Learning and Memory • Process of converting immediate or working memory into long-term memory involves a process called ___________ (Figure 12.37) • Formation and storage of declarative memory appears to require hippocampus (component of limbic system); immediate and shortterm memories are likely stored in this region © 2016 Pearson Education, Inc. Learning and Memory • Process of converting immediate or working memory into long-term memory involves a process called consolidation (Figure 12.37) • Formation and storage of declarative memory appears to require hippocampus (component of limbic system); immediate and shortterm memories are likely stored in this region © 2016 Pearson Education, Inc. Learning and Memory • ___________) – mechanism by which hippocampal neurons encode long-term declarative memories, seems to involve an increase in synaptic activity between associated neurons; example of Cell-Cell Communication Core Principle • Although hippocampus is required to form new declarative memories, longterm memories are not stored in this region; stored in cerebral cortex that correlates with their functions • Retrieval of memories seems to be mediated by pathways involving hippocampus and prefrontal cortex © 2016 Pearson Education, Inc. Learning and Memory • Long-term potentiation (LTP) – mechanism by which hippocampal neurons encode long-term declarative memories, seems to involve an increase in synaptic activity between associated neurons; example of Cell-Cell Communication Core Principle • Although hippocampus is required to form new declarative memories, longterm memories are not stored in this region; stored in cerebral cortex that correlates with their functions • Retrieval of memories seems to be mediated by pathways involving hippocampus and prefrontal cortex © 2016 Pearson Education, Inc. Learning and Memory Figure 12.37 Pathways for consolidation of memories. © 2016 Pearson Education, Inc. Learning and Memory • Emotion – complex combination of three separate phenomena: • Visceral motor responses – blushing or heart racing; mediated by hypothalamus • Somatic motor responses – smiling, laughing, frowning, and crying; mediated by hypothalamus and limbic cortex through reticular formation © 2016 Pearson Education, Inc. Learning and Memory • Emotion (continued): • “Feelings” – highly subjective; most complex; integrated with sensory and/or cognitive stimuli • Feeling sad when remembering a lost pet or feeling tense when watching a suspenseful movie • Amygdala receives input from brainstem, thalamus, cerebral cortex, and basal nuclei, analyzes emotional significance of stimuli; creates associations between different stimuli; projects to prefrontal cortex © 2016 Pearson Education, Inc.