EXSC 224 Week 3 Notes
EXSC 224 Week 3 Notes Exsc 224
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This 11 page Class Notes was uploaded by Jane Warther on Sunday January 31, 2016. The Class Notes belongs to Exsc 224 at University of South Carolina taught by Dr. Thompson in Spring 2016. Since its upload, it has received 48 views. For similar materials see Anatomy and Physiology 224 in Education and Teacher Studies at University of South Carolina.
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Date Created: 01/31/16
Chapter 12 Lecture 1 The Cerebrum Part 1 1/26/16 (c) Secondary brain (d) Adult brain (e) Adult vesicles structures neural canal regions Cerebrum: cerebral Telencephalon hemispheres (cortex, Lateral white matter, basal n)cleitricles Diencephalon Diencephalon (thalamus, hypothalamus,rd ventricle epithalamus), retina Mesencephalon Brain stem: midbrain Cerebral aqueduct Metencephalon Brain stem: pons Fourth Cerebellum ventricle Myelencephalon Brain stem: medulla oblongata Spinal cord Central canal -4 weeks after conception, neural tube forms, precursor to brain -Week after neural tube, cells that form it will grow and will see changes in shape to look like the picture in the graph above -even in development brain and spinal cord is continuous -as brain develops certain regions develop differently Space Restriction and Brain Development Five week of development- brain can’t grow longer, has no where to go so it starts to fold to fit it into the space available to it 13 weeks- still folding to be compact as possible, bones starting to develop 26 weeks- as brain continues to grow it pushes against the bone which causes the cerebrum to start to fold, see gyri and sulci start to occur Birth- highly folded Because outside of brain is folded, it allows surface area to increase but not the volume Gray and White Matter Gray matter= neuron cell bodies o Cortex over cerebrum and cerebellum and central portion of spinal cord o Forms nuclei deep within brain o Increases surface area by following all the sulci and gyri o more cortex present, the more cell bodies and the more function White matter= bundles of axons o Axons tend to be myelinated o Forms tracts that connect parts of brain o Ascending and descending tracts in the spinal cord Ventricles of the Brain Connected to one another by tubes and converge to the central canal of the spinal cord Lined by ependymal cells Contain cerebrospinal fluid (CSF) o Produced in lateral and fourth ventricle by choroid plexuses Choroid plexus consist of ependymal cells and capillaries o Helps slow brain down when hit, decrease magnitude of injury o Can leave ventricle by lateral and median aperture Lateral ventricles o One in each cerebral hemisphere o Connected by interventricular foramen Third ventricle o Only one, in center of brain o Descends into cerebral aqueduct Fourth ventricle o Cerebral aqueduct connects third and fourth ventricle o Down to spinal cord from here Cerebral Hemisphere Ridges (gyri) Shallow grooves (sulci) Deep grooves (fissures) o Transverse cerebral fissure- separate cerebrum from cerebellum o Longitudinal fissure- separates right and left hemispheres 5 lobes o Frontal Central sulcus separates frontal and parietal lobe o Parietal o Occipital o Temporal o Gyri of insula To be found pull temporal lobe down o Can communicate and work together if necessary Functional Areas of the Cerebral Cortex The three types of functional areas are: o Motor areas- control voluntary movement Only found in frontal lobe- only a portion of it Primary motor cortex- the gyrus immediately anterior to central sulcus Premotor cortex- activates primary motor cortex Frontal eye field- blink, moves eyes Broca’s area- specific to speech Injure this area, can’t speak Activated even when thinking about speaking Always in dominant hemisphere of brain o Sensory areas- conscious awareness of sensation Found in the other four lobes o Association areas- integrate diverse information All association areas store memory Conscious behavior involves the entire cortex Primary Motor Cortex Exists on both hemispheres, controls opposite sides Large pyramidal cells of the precentral gyri Long axons → pyramidal (corticospinal) tracts Allows conscious control of precise, skilled, voluntary movements Motor homunculi: upside-down caricatures representing the motor innervation of body regions o Homunculus- motor map in precentral gyrus o Not proportional o The amount of cortex devoted to a region is proportional to the amount of fine motor skill in that area- ex. Hands have a lot of cortex devoted to them because of it has more fine motor movements o Come back and insert picture of map- be very specific when naming and commit to memory Premotor Cortex Anterior to the precentral gyrus Controls learned, repetitious or patterned motor skills Coordinates simultaneous or sequential actions Involved in the planning of movements that depend on sensory feedback Can learn new motor tasks throughout life If there is an injury, the brain is plastic enough to adapt somewhat Broca’s Area Part of premotor area Anterior to the inferior region of the premotor area Present in one hemisphere (usually the left) A motor speech area that directs the muscles of the tongue Is active as one prepares to speak Sensory Areas No sensory input from the frontal lobe Olfactory area Gustatory cortex Visceral sensory area Vestibular cortex Primary Somatosensory Cortex In parietal lobe In the postcentral gyri Receives sensory information from the skin, skeletal muscles, and joints Capable of spatial discrimination: identification of body region being stimulated Has its own map-homunculus o Similar to primary motor map o Not perfect, responds to amount of sensory(tactile) info in the body o More sensory detection in hands than in other regions of the body Somatosensory Association Cortex In parietal lobe Posterior to the primary somatosensory cortex Integrates sensory input from primary somatosensory cortex Determines size, texture, and relationship of parts of objects being felt Store some memory here Visual Areas In occipital lobe Primary visual cortex o Receives visual information from the retinas Visual association area o Surrounds the primary visual cortex o Uses past visual experiences to interpret visual stimuli ( color, from, and movement) o Complex processing involves entire posterior half of the hemispheres Auditory Areas Found in temporal lobe- medial side Primary auditory cortex o Interprets information from inner ear as pitch, loudness and location Auditory association area o Stores memories of sounds and permits perception of sounds Olfactory Cortex Medial aspect of temporal lobes (in piriform lobes) Region of conscious awareness of odors Insula Sense of taste Have primary and association area Multimodal Association Areas Receive input from multiple sensory areas Sends outputs to multiple areas, including the premotor cortex Allow us to give meaning to information received, store it as memory, compare it to previous experience , and decide on action to take Three parts o 1. Anterior association area (prefrontal cortex) Anterior part of frontal lobe Most complicated cortical region Involved with intellect, cognition, recall, and personality Contains working memory needed for judgement, reasoning, persistence, and conscience Development depends on feedback form social environment Separates us from all other animal species on earth o 2. Posterior association area Large region in temporal, parietal and occipital lobes (sensory lobes) Associates areas communicate to form a multimodal association Plays a role in recognizing patterns and faces and localizing us in space Involved in understanding written and spoken language (Wernicke’s area) Completely injure, won’t be able to read or understand spoken language Sits at intersection of occipital, temporal and parietal lobes o 3. Limbic association area Part of the limbic system Involved in learning Provides emotional impact that helps establish memories- primarily involved with this Hippocampus Cingulate gyrus Parahippocampal gyrus Amygdala Lateralization of Cortical Function Lateralization o Division of labor between hemispheres o Ex. Broca’s area or Wernicke’s area- both appear on only one side, the dominant side of the brain Right handed- they are on left hemisphere Left-handed- on the right hemisphere Cerebral dominance o Designates the hemisphere dominant for language (left hemisphere in 90% of people) Left hemisphere o Controls language, math, and logic Right hemisphere o Insight , visual-spatial skills, intuition, and artistic skills Left and right hemispheres communicate via fiber tracts in the cerebral white matter Cerebral White Matter Myelinated fibers and their tracts Responsible for communication o Commissures (in corpus callosum)- connect gray matter of the two hemispheres o Association fibers- connect two gyri of the same hemisphere o Projection fibers- (corona radiate) connect the hemispheres with lower brain or spinal cord Can be motor(descending to the cortex) or sensory(ascending to the cortex) Basal Nuclei( Ganglia) Subcortical nuclei Part of the CNS-nuclei Plays important role in inhibiting muscle contractions o In stopping movement Works through premotor cortex which then sends info to primary motor cortex, not related to proprioception Functionally associated with the subthalamic nuclei (diencephalon) and the substantia nigra (midbrain) Functions o Though somewhat elusive, the following are thought to be functions of basal nuclei Influence muscular control Help regulate attention and cognition Regulate intensity of slow or stereotyped movements Inhibit antagonistic and unnecessary movements Chapter 12 Lecture 2 The Diencephalon, Midbrain, and Brain Stem 1/28/16 Diencephalon Three paired structures o Thalamus Plays essential roles throughout body A cluster of nuclei Each of nuclei receive info from specific sources, relay info to right part of brain Traffic director and editor(helps to determine what is important/filter) o Hypothalamus Plays essential roles throughout body Only one Small region, referred to a neuroendocrine organ because it is also endocrine gland Controls large portions of endocrine system Made of small nuclei o Epithalamus Helps you fall asleep Encloses the third ventricle Associate with cerebrum Pineal gland o Secretes melatonin o Light sensitive- how it regulations sleep patterns Hypothalamic Function Autonomic control- center for many visceral functions (blood pressure, rate and force of heartbeat, digestive tract motility) Center for emotional response: involved in perception of pleasure, fear, and rage and in biological rhythms and drives Regulates body temperature, food intake, water balance, and thirst Regulates sleep and the sleep cycle o Causes you to wake up Controls release of hormones by the anterior pituitary Produces posterior pituitary hormones One of the few parts of the brain that doesn’t have a blood brain barrier- window to the world Epithalamus Most dorsal portion of the diencephalon; forms rood of the third ventricle Pineal gland- extends from the posterior border and secretes melatonin o Melatonin- helps regulate sleep-wake cycles , taken before bed can help you go to sleep o Regulated by light exposure Brain Stem Automatic functions here, no cognition or thinking 3 regions o Midbrain Cerebral peduncles Contain pyramidal motor tracts Cerebral aqueduct Channel between third and fourth ventricles Corpora quadrigemina o 2 regions Superior- associated with eyes Receive info from optic nerve See something out of corner of eye Reflex Inferior Does the same thing as hearing Hearing loud noise and then startling o Pons Forms part of the anterior wall of the fourth ventricle Origin of cranial nerves V(trigeminal), VI(abducens) and VII(facial) Some of the nuclei of the reticular formation Nuclei that help maintain normal rhythm of breathing Pyramidal tracts run through ventral region of pons Talking about motor so they are descending tracts Medial lemniscus Associated with sensory info(ascending tract) o Medulla oblongata Only thing you can’t live without Autonomic reflex centers Cardiovascular center o Heart rate/force o Blood vessel diameter Respiratory centers o Generate respiratory rhythm o Control rate and depth of breathing, with pontine centers Additional centers regulate o Vomiting o Hiccupping o Swallowing o Coughing o Sneezing Pyramids- two ventral longitudinal ridges formed by pyramidal tracts Decussation of the pyramids- crossover of the corticospinal tracts Does not have blood brain barrier Blood brain barrier is tight junctions between capillaries Cerebellum Smooth coordinated muscle contraction Proprioception- awareness of body’s position and momentum Recognizes and predicts sequences of events during complex moments Plays a role in nonmotor functions such as word association and puzzle solving Sits below occipital lobe of cerebrum o Separated by transverse fissure Folded like cerebrum, but ridges are finer 11% of brain mass Does not function in conscious thought Subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction Receives info from limbs/muscles as moving, send info to thalamus before it makes it way to the premotor cortex o Once it gets to premotor cortex you can decide what to do Smooth coordinated muscle contraction Proprioception- awareness of body’s position and momentum Has three homunculi Epsilateral- means same side o Cerebellum receives info from the epislateral side, once info processed go to thalamus on left side and then to left side of brain Contralateral-opposite side Functional Brain Systems Networks of neurons that work together and span wide areas of the brain o Limbic system o Reticular formation Limbic system Exist mostly in cerebrum Works with hypothalamus with eliciting emotional and stress responses Emotional or affective brain o Amygdala- recognizes angry of fearful facial expression, assesses danger, and elicits the fear response Plays role in memory specific to emotion o Cingulate gyrus-plays a role in expressing emotions via gestures, and resolves mental conflict o Hippocampus- memory Plays role in declarative memory- facts 2- one on each side Formation of memory Puts emotional responses to odors o Ex. Skunks smell bad Reticular Formation Three broad columns along the length of the brain stem o Raphe nuclei o Medial group of nuclei o Lateral group of nuclei o Neurons are found in other places in the body RAS (reticular activating system) o Send impulses to the cerebral cortex to keep it conscious and alert o Filters out repetitive and weak stimuli (~99% of all stimuli) o Severe injury results in permanent unconsciousness (coma) Motor function o Helps control coarse limb movements o Reticular autonomic centers regulate visceral motor functions Vasomotor Cardiac Respiratory centers Consciousness It means you can respond to stimuli o Can be fleeting(syncope/fainting)-not enough blood flow going to the brain, goes into unconsciousness) Conscious perception of sensation Sleep is a state of semi-consciousness, can be woken from sleep Voluntary initiation and control movement Capabilities associated with higher mental processing (memory, logic, judgement) Loss of consciousness(fainting or syncopy) is a signal that brain function is impaired Clinically defined on a continuum that grades behavior in response to stimuli o Alertness o Drowsiness(lethargy) o Stupor- not unconsciousness next, only responsive to certain types of stimuli like pain Is not sleep o Coma Memory Storage and retrieval of information All learning comes from five senses o Touch o Smell o Vision o Hearing o Taste Two stages of storage o Short-term memory (STM or working memory)- temporary holding of information; limited to seven or eight pieces of information o Long-term memory (LTM) has limitless capacity Transfer from STM to LTM o Factors that affect transfer from STM to LTM Emotional state- best it alert, motivated, surprised, and aroused Rehearsal- repetition and practice Association- tying new information with old memories Automatic memory- subconscious information stored in LTM Declarative memory (factual knowledge) o Explicit information o Related to our conscious thoughts and our language ability o Stored in LTM with context in which it was learned Nondeclarative memory o Less conscious or unconscious o Acquired through experience and repetition o Best remembered by doing: hard to unlearn o Includes Procedural (skills) memory Motor memory (cerebellum) Emotional memory(amygdala) Quiz 2 1. What lobe is the primary motor cortex in? Frontal lobe 2. List two types of info the homunculus the somatosensory cortex lets us interpret. -location, type of sensory input, intensity 3. If a neurotransmitter were to bind to a ligand-gated receptor and caused an IPSP, what it is the ion most likely to flow into the cell? -potassium or chloride 4. list similarity and difference between action and graded potential -graded potential occurs in dendrite or soma -both are changes in membrane potential -action potentials are a large change in membrane potential -graded potentials vary -action potentials- focus on depolarizing 5. What is the difference between absolute and relative refractory periods? -absolute refractory period can’t depolarize again where relative can -absolute refractory occurs first with membrane potential above threshold -during relative refractory period, most of the time the cell is hyperpolarized
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