* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CNS – composed of the brain and spinal cord Cephalization
Metastability in the brain wikipedia , lookup
Neuroesthetics wikipedia , lookup
Cortical cooling wikipedia , lookup
Time perception wikipedia , lookup
Neuroeconomics wikipedia , lookup
Neuroplasticity wikipedia , lookup
Eyeblink conditioning wikipedia , lookup
Human brain wikipedia , lookup
Cognitive neuroscience of music wikipedia , lookup
Aging brain wikipedia , lookup
Neural correlates of consciousness wikipedia , lookup
Central Nervous System (CNS) CNS – composed of the brain and spinal cord Cephalization Elaboration of the anterior portion of the CNS Increase in number of neurons in the head Highest level is reached in the human brain Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings I take exception to that! Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Surface anatomy includes cerebral hemispheres, cerebellum, and brain stem Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development During the first 26 days of development: Ectoderm thickens forming the neural plate The neural plate invaginates, forming the neural folds Superior edges fuse forming neural tube which detaches from the ectoderm and sinks deeper Neural tube differentiates into the CNS Brain forms from neural tube (rostrally) as well as spinal cord (posterior/dorsally) Neural crest cells give rise to some neurons destined to reside in ganglia Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.1 Brain Development: Primary Brain Vesicles The anterior end of the neural tube expands and constricts to form the three primary brain vesicles Prosencephalon – the forebrain Mesencephalon – the midbrain Rhombencephalon – hindbrain Remainder of neural tube becomes the spinal cord Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neural Tube and Primary Brain Vesicles Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.2a, b Secondary Brain Vesicles In week 5 of embryonic development, secondary brain vesicles form Telencephalon and diencephalon arise from the forebrain Mesencephalon remains undivided Metencephalon and myelencephalon arise from the hindbrain Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Secondary Brain Vesicles Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.2c Adult Brain Structures Fates of the secondary brain vesicles: Telencephalon – cerebrum: cortex, white matter, and basal nuclei Diencephalon – thalamus, hypothalamus, and epithalamus Mesencephalon – brain stem: midbrain Metencephalon – brain stem: pons Myelencephalon – brain stem: medulla oblongata Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adult Neural Canal Regions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.2c, d Adult Neural Canal Regions Adult structures derived from the neural canal Telencephalon – lateral ventricles Diencephalon – third ventricle Mesencephalon – cerebral aqueduct Metencephalon and myelencephalon – fourth ventricle Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adult Neural Canal Regions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.2c, e Space Restriction and Brain Development Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.3 Space Restriction and Brain Development Flexures: midbrain and cervical, which bend the forebrain toward the brain stem Cerebral hemispheres: grow posteriorly and laterally and envelop the diencephalon and midbrain Continued growth causes the surface to crease and fold producing convolutions thus increasing the surface area Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Basic Pattern of the Central Nervous System Spinal Cord Central cavity surrounded by a gray matter core External to which is white matter composed of myelinated fiber tracts Brain Similar to spinal cord but with additional areas of gray matter Cerebellum has gray matter in nuclei Cerebrum has nuclei and additional gray matter in the cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Basic Pattern of the Central Nervous System Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.4 Ventricles of the Brain Continuous with one another and with the central canal of the spinal cord Filled with cerebrospinal fluid and lined with ependymal cells Paired lateral ventricles C-shaped reflects the pattern of cerebral growth Septum pallucidum separates lateral ventricles via the interventricular foreamen Third ventricle connected to the fourth ventricle via the cerebral aquaduct Fourth ventricle is continuous with the central canal of the spinal cord Fourth ventricle is also continuous with the fluid filled space surrounding the brain (subarachnoid) via lateral and medial apertures. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles of the Brain Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.5 Cerebral Hemispheres Form the superior part of the brain and make up 83% of its mass Contain ridges (gyri) and shallow grooves (sulci) Contain deep sulci called fissures Are separated by the longitudinal fissure Transverse fissure separates the cerebral hemispheres from the cerebellum Prominent gyri and sulci are the same in all human brains and are anatomical landmarks Have three basic regions: cortex, white matter, and basal nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere Prominent sulci divide the hemispheres into five lobes: Frontal, parietal, temporal, occipital, and insula These are named for the cranial bones under which they lie Central sulcus – separates the frontal and parietal lobes. Bordered by the precentral gyrus (anteriorly) and the postcentral gyrus (posteriorly) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Lobes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.6a–b Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere Parieto-occipital sulcus – separates the parietal and occipital lobes Lateral sulcus – outlines the temporal lobe and separates the parietal and temporal lobes Insula: buried within the lateral sulcus and forms part of the floor of the cerebral hemispheres Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral Cortex: Our “conscious mind” The cortex – superficial gray matter; accounts for 40% of the mass of the brain. Gray matter: neuron cell bodies, dendrites, associated glia, blood vessels It enables sensation, communication, memory, understanding, and voluntary movements Each hemisphere acts contralaterally (controls the opposite side of the body) Cerebral cortex has been extensively mapped Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Areas of the Cerebral Cortex The three types of functional areas are: Motor areas – control voluntary movement Sensory areas – conscious awareness of sensation Association areas – integrate diverse information All neurons here are interneurons not sensory & motor neurons Each hemisphere is chiefly concerned with the sensory and motor functions of the opposite side of the body Each side has specialization and is not necessarily bilateral Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Areas of the Cerebral Cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.8a Functional Areas of the Cerebral Cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.8b Cerebral Cortex: Motor Areas (Voluntary Movement) Lie in the posterior part of the frontal lobes: Primary (somatic) motor cortex Premotor cortex Broca’s area Frontal eye field Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Primary Motor Cortex (Brodmman’s Area #4) Located in the precentral gyrus of the frontal lobe of each hemisphere Pyramidal cells allow conscious control of precise, skilled, voluntary movements. Their long axons project into the spinal cord forming the massive pyramidal tracts (corticospinal tracts) The entire body is represented spatially in the primary motor cortex of each hemisphere (this type of mapping is called somatotopy) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Premotor Cortex (Brodmman’s Area #6) Located anterior to the precentral gyrus in the frontal lobe Controls learned, repetitious, or patterned motor skills Coordinates movement by sending impulses to the primary motor cortex Involved in the planning of movements Controls voluntary movements that depend on sensory feedback Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Broca’s Area: Brodmann Area #44 & 45 Broca’s area Located anterior to the inferior region of the premotor area Present in one hemisphere (usually the left) A motor speech area that directs muscles of the tongue Is active as one is planning to speak Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Frontal Eye Field: Brodmann’s Area #8 Frontal eye field Located anterior to the premotor cortex and superior to Broca’s area Controls voluntary eye movement Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensory Areas Primary somatosensory cortex Somatosensory association cortex Visual and auditory areas Olfactory, gustatory, and vestibular cortices Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensory Areas Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.8a Primary Somatosensory Cortex: Brodmann’s Area #1-3 Located in the postcentral gyrus of parietal lobe Receives info. from sensory receptors in the skin and proprioceptors in the skeletal muscles, joints, tendons Neurons identify the body region being stimulated (spatial discrimination) Body is represented spatially: contralaterally and upside down The amount of sensory cortex devoted to a given body region is related to the degree of sensitivity in that region, and not the body size (e.g. face, lips, fingertips) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Somatosensory Association Cortex: Brodmann’s Areas 5 &7 Located posterior to the primary somatosensory cortex Integrates sensory information relayed from the primary somatosensory cortex to produce an understanding of the object being felt Determines size, texture, and relationship of parts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Visual Areas: Brodmann’s Areas 17-19 Primary visual (striate) cortex Seen on the extreme posterior tip of the occipital lobe Most of it is buried in the calcarine sulcus Receives visual information from the retinas Visual association area Surrounds the primary visual cortex Interprets visual stimuli (e.g., color, form, and movement) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Auditory Areas: Brodmann’s Areas 41-43 Primary auditory cortex Located at the superior margin of the temporal lobe Receives information related to pitch, rhythm, and volume Auditory association area Located posterior to the primary auditory cortex Stores memories of sounds and permits perception of sounds Wernicke’s area Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Olfactory Cortex: Brodmann’s Areas: 28 & 34 Located in the medial aspect of the temporal lobe dominated by the uncus Afferent fibers from smell receptors in the superior nasal cavities send impulses along olfactory tracts and relay them to the olfactory cortex The O.C. is part of the primitive rhinencephalon Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings …and the other corteces Gustatory cortex (located in the insula) Deep to the temporal lobe Taste Visceral sensory area (also in the insula) Located just posterior to the gustatory cortex Perception of visceral sensations Vestibular (equilibrium) cortex Located in the posterior part of the insula Balance Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multimodal Association Areas Information flows from sensory neurons to Primary sensory cortex to Sensory association cortex to Multimodal association cortex Gives meaning to the information Stores it in memory Decision making area Relay decisions to premotor cortex and then the motor cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Prefrontal Cortex (Anterior Association Area) Located in the anterior portion of the frontal lobe Most complicated cortical region Involved with intellect, cognition, recall, and personality Necessary for judgment, reasoning, persistence, and conscience Matures slowly, dependent on positive/negative feedback Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Posterior Association Area Region encompassing parts of: temporal, parietal, and occipital lobes Involved in recognizing patterns, surroundings, bringing different sensory inputs into a whole Brings conscious attention to an area in space or to an area of one’s own body Problems here can result in a smelly, half naked lady! Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Language Areas Located in a large area surrounding the left (or language-dominant) lateral sulcus Major parts and functions: Wernicke’s area –sounding out unfamiliar words Broca’s area – speech preparation and production Lateral prefrontal cortex – language comprehension and word analysis Lateral and ventral temporal lobe – coordinate auditory and visual aspects of language Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lateralization of Cortical Function Lateralization – each hemisphere has abilities not shared with its partner Cerebral dominance – designates the hemisphere dominant for a given task Left hemisphere – controls language, math, and logic E.g. Dad buys half a cow for conversation sake Right hemisphere – controls visual-spatial skills, emotion, and artistic skills Most “righties” are left cerebral dominant, while most “south paws” are right cerebral dominant. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral White Matter Located deep to the cortical grey matter It is responsible for communication between the cerebral cortex and lower CNS center, and within areas of the cerebrum Consists of deep myelinated fibers and their large tracts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral White Matter Tracts are classified according to the direction in which they run Types include: Commissures – connect corresponding gray areas of the two hemispheres. E.g. corpus collosum Fibers run horizontally Association fibers – connect different parts of the same hemisphere E.g. connect adjacent gyri Long fibers can connect different cortical lobes Fibers run horizonatally Projection fibers – enter the hemispheres from lower brain or cord centers Tie the cortex to the rest of the nervous system and to the body’s receptors and effectors E.g. corona radiata: fan like projection of fibers from the brain stem to the cortex Fibers run vertically Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fiber Tracts in White Matter Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.10a Basal Nuclei Masses of gray matter found deep within the cortical white matter The corpus striatum (striped appearance) is composed of three parts Caudate nucleus Lentiform nucleus – composed of the putamen and the globus pallidus Fibers of internal capsule running between and through caudate and lentiform nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Basal Nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.11a Basal Nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.11b Functions of Basal Nuclei Nuclei of the corpus striatum receive input from the entire cerebral cortex Output nuclei of the basal nuclei project to the premotor and prefrontal cortices and influence muscle movements directed by the primary motor cortex No direct access to the motor pathways Disorders of the B.N. result in too much or too little movement Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Diencephalon Central core of the forebrain Surrounded by the cerebral hemispheres Consists of three paired structures – thalamus, hypothalamus, and epithalamus Encloses the third ventricle Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Diencephalon Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.12 Thalamus Paired, egg-shaped masses that form the superolateral walls of the third ventricle Connected at the midline by the intermediate mass Contains four groups of nuclei – anterior, ventral, dorsal, and posterior Nuclei project and receive fibers from the cerebral cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thalamus Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.13a Thalamic Function Afferent fibers from all senses and all parts of the body converge and synapse in the thalamus Impulses of similar function are sorted out, edited, and relayed as a group All inputs ascending to the cerebral cortex pass through the thalamus Mediates sensation, motor activities, cortical arousal, learning, and memory Thalamus is the “gateway” to the cerebral cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hypothalamus Located below the thalamus, it caps the brainstem and forms the inferolateral walls of the third ventricle Extends from the optic chiasma to the posterior margin of the mammillary bodies Mammillary bodies Small, paired nuclei bulging anteriorly from the hypothalamus Relay station for olfactory pathways Infundibulum – stalk of the hypothalamus; connects to the pituitary gland Main visceral control center of the body Vital for homeostasis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hypothalamic Nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.13b Hypothalamic Function Autonomic control center: controls autonomic nervous system. Regulates cardiac and smooth muscle Regulates gland secretion Influences blood pressure, heartbeat rate, digestive tract motility, eye pupil size Emotional response center Body temperature regulation Regulates the feeling of hunger and satiation Regulation of water balance and thirst Sweating, shivering Regulation of food intake Center for pleasure, fear, rage Regulates release of antidiuretic hormone causing kidneys to retain water Regulates sleep wake cycle Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocrine Functions of the Hypothalamus Releasing hormones control secretion of hormones by the anterior pituitary gland The supraoptic and paraventricular nuclei produce ADH and oxytocin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithalamus Most dorsal portion of the diencephalon; forms roof of the third ventricle Pineal gland – extends from the posterior border and secretes melatonin Melatonin – a hormone involved with sleep regulation, sleep-wake cycles, and mood Choroid plexus – a structure that secretes cerebral spinal fluid (CSF) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithalamus Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.12 Human Brain: Ventral Aspect Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.14 Brain Stem Consists of three regions – midbrain, pons, and medulla oblongata Similar to spinal cord but contains embedded nuclei Controls automatic behaviors necessary for survival Provides the pathway for tracts between higher and lower brain centers Associated with 10 of the 12 pairs of cranial nerves Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Stem Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.15a Brain Stem Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.15b Brain Stem Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.15c Midbrain Located between the diencephalon and the pons Midbrain structures include: Cerebral peduncles – two bulging structures that contain pyramidal motor tracts descending toward the spinal cord Cerebral aqueduct – hollow tube that connects the third and fourth ventricles Various nuclei Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Midbrain Nuclei Corpora quadrigemina – four domelike protrusions of the dorsal midbrain (superior and inferior colliculi) Superior colliculi: visual reflex centers Inferior colliculi: auditory relay (startle reflex) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Midbrain Nuclei 2 pigmented nuclei: Substantia nigra – pigmented from melanin Precursor of dopamine released here. Disorders here, e.g. Parkinson’s disease Red nucleus – largest nucleus of the reticular formation red coloration due to high degree of vascularization Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pons Bulging brainstem region between the midbrain and the medulla oblongata Forms part of the anterior wall of the fourth ventricle Formed of tracts coursing in 2 directions Deep projections: connect higher brain centers and spinal cord Superficial projections relay between the motor cortex of the cerebrum and the cerebellum Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Medulla Oblongata Most inferior part of the brain stem Along with the pons, forms the ventral wall of the fourth ventricle Contains a choroid plexus of the fourth ventricle Pyramids – two longitudinal ridges formed by corticospinal tracts Decussation of the pyramids – crossover points of the corticospinal tracts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Medulla Oblongata Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.16c Medulla Nuclei Inferior olivary nuclei – gray matter that relays sensory information on the state of stretch of muscles and joints to the cerebellum Cochlear nuclei: auditory relays Vestibular nuclear complex – synapses that mediate and maintain equilibrium Nucleus gracilis and caneatus: where somatic sensory information ascends from the spinal cord to the somatosensory coretex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Medulla Nuclei Involved in autonomic reflex center involved in homeostasis Cardiovascular control center – adjusts force and rate of heart contraction Respiratory centers – control rate and depth of breathing Additional centers – regulate vomiting, hiccuping, swallowing, coughing, and sneezing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Located dorsal to the pons and medulla Protrudes under the occipital lobes of the cerebrum Makes up 11% of the brain’s mass Provides precise timing and appropriate patterns of skeletal muscle contraction E.g. coordination Cerebellar activity occurs subconsciously Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.17b Anatomy of the Cerebellum Two bilaterally symmetrical hemispheres connected medially by the vermis Contains folia – transversely oriented gyri Fissures subdivide each hemisphere into three lobes – anterior, posterior, and flocculonodular Neural arrangement – gray matter cortex, internal white matter, scattered nuclei Arbor vitae – distinctive treelike pattern of the cerebellar white matter Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebellar Peduncles Three paired fiber tracts that connect the cerebellum to the brain stem All fibers in the cerebellum are ipsilateral Superior peduncles connect the cerebellum to the midbrain Middle peduncles connect the pons to the cerebellum Inferior peduncles connect the medulla to the cerebellum Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebellar Processing Cerebellum receives impulses of the intent to initiate voluntary muscle contraction Proprioceptors and visual signals “inform” the cerebellum of the body’s condition Cerebellar cortex calculates the best way to perform a movement A “blueprint” of coordinated movement is sent to the cerebral motor cortex Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings KU Game Day! Tues. 6 pm Tues. 8 pm Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings