Chapter 14, Part 2! The Cerebrum and Cranial pp. 482 505! SECTION 14-9! The cerebrum, the largest region of the brain, contains motor, sensory, and association areas! 2! White Matter of the Cerebrum! 1. Association fibers! Interconnect areas of cortex in same hemisphere Arcuate fibers: gyrus to gyrus connections! Longitudinal fasciculi: frontal lobe to other lobes on same side! 2. Commissural fibers!! Interconnect hemispheres! E.g. corpus callosum! 3! 1!
White Matter of the Cerebrum 2 Figure 14-14! 3. Projection fibers (e.g. internal capsule)! Connect cerebrum to diencephalon, brain stem, cerebellum, spinal cord! Association fibers! 4! The Cerebral Hemispheres Figure 14-16! PLAY! 5! Basal Nuclei (Formerly Called Ganglia )! Paired nuclei! Gray matter deep to lateral ventricles! Functions:! Subconscious control of muscle tone! Coordination of learned movements! e.g. arm-swinging during walking! e.g. stabilizing shoulder joint while reaching! 6! 2!
Basal Nuclei - Control of Muscle Tone! Receive inhibitory (dopamine - DA) input from substantia nigra! Cerebrum! Substantia nigra! +! Thalamus! +!! Basal nuclei! DA! +! skeletal muscle tone! How is this system involved in Parkinson s disease?! 7! Cerebral Cortex Functional Overview Table 14-3! 8! Functions of the Frontal Lobe 1! 1. Primary Motor Cortex on precentral gyrus! Contains pyramidal cells! Movement of specific muscles or groups! Receives input from premotor cortex! Wilder Penfield s experiments! Motor homunculus Area of cortex is proportional to the number of motor units controlling a body part! 9! 3!
! Chapter 14 Part 2 Brain/Cranial Motor Homunculus! 10! Functions of the Frontal Lobe 2! 2. Somatic Motor Association Area (a.k.a. premotor cortex)! Coordinated, learned movements of muscle groups! e.g. typing, playing the piano! i.e. a pattern for learned movements is stored in the premotor cortex! Info pathway: prefrontal cortex premotor cortex primary motor cortex skeletal muscles! 11! Functions of the Frontal Lobe 3! 3. Prefrontal Cortex - a multimodal association area! Integrates info from sensory areas abstract thinking! Phineas P. Gage - 1848! Industrious, responsible, considerate! Damaged prefrontal cortex Personality changed:! Quarrelsome, lazy, irresponsible! i.e. individuality, personality reside in the brain! Long-term planning, motivation! 12! 4!
! Chapter 14 Part 2 Brain/Cranial Phineas P. Gage - Prefrontal Lobotomy! 13! Functions of the Frontal Lobe 4! 4. Motor Speech (Broca s) Area! An association area! Connected to Wernicke s area! Translates thought into speech! Regulates breathing and vocalization (muscular movements) for speech! Damage can make sounds, but not words! On left side in > 90% of population! 5. Frontal Eye Field Area! Voluntary scanning movements - e.g. reading! 14! Functions of Parietal Lobe 1! 1. Primary Sensory (Somesthetic) Cortex! On post-central gyrus! General sensation info sent here from thalamus! Contains four sensory homunculi! Size of area proportional to number of receptors! Wilder Penfield s! experiments again! 15! 5!
! Chapter 14 Part 2 Brain/Cranial Sensory Homunculus! 16! Sensory Homunculus Jacksonian March! Also shows organization of sensory homunculus! Epileptic episode:! Numbness, burning, prickling sensation spreads! e.g. Starts in fingertips on left side left hand left arm left shoulder and back down left leg! 17! Functions of Parietal Lobe 2, Insula! 2. Somesthetic Multimodal Association Area! Input from primary sensory cortex and thalamus! Integrates and interprets sensations! E.g. knowing the shape and texture of an object when eyes are closed! E.g. light touch on arm is a fly, not a truck! Insula : Primary Gustatory Area! Taste and other limbic-type functions! 18! 6!
! Chapter 14 Part 2 Brain/Cranial Functions of Temporal Lobe! 1. Primary Auditory Area! Input from cochlea! Basic character of sound! 2. Auditory Association Area (Wernicke s area)! Unimodal speech association area! Connected to Broca s area! Interprets the meanings of spoken words! Damage can t understand words! 3. Primary Olfactory Area! Input from olfactory tract! 19! Functions of Occipital Lobe! 1. Primary Visual Area! Input from retina (via lateral geniculate)! Shape, color, direction of movement! 2. Visual Association Area! Receives input from #1! Recognition of visual info! 20! Association Areas! Interpret information from multiple sources!! Unimodal association areas:! Interpret information about a particular sensation (e.g. vision)!! Multimodal association areas:! Integrate sensory inputs of different types! Link sensory input to voluntary movements!! 21! 7!
Association Areas! No, you don t have to memorize this. Just appreciate the complexity and recognize the difference between unimodal and multimodal association areas.! 22! Integrative (Association) Areas 2! General interpretive (Wernicke s) area! Receives/integrates sensory info from many areas! Part of language areas! Helps interpret meaning of spoken words! Broca s area (Speech center)! Regulates laryngeal, pharyngeal, respiratory muscles for speech! Damage: know words you want to say, but can t actually say them! 23! Hemispheric Lateralization Figure 14-16! Part of language area! 24! 8!
Brain Lateralization! Right vs. Left Brain! Left brain controls right side of body! Right brain controls left side of body! Communication between hemispheres via commissures (e.g. corpus callosum)! Language centers! (e.g. verbal hemisphere: turning thoughts into words)! Usually localized to left hemisphere! Left side more verbal! Right side more spatial! 25! Split Brain Experiments 1! Left hemisphere = verbal hemisphere! Normal subject: Corpus callosum intact! Allows communication between hemispheres! First slide:! 1. Show apple to right visual field! Patient says apple! 2. Show apple to left visual field! Patient says apple! https://www.youtube.com/watch?v=zmlzp1vcano! 26! Split Brain Experiments 2! Apple in right visual field! Apple in left visual field! Verbal! Hemisphere! Verbal! Hemisphere! 27! 9!
Split Brain Experiments 3! Corpus callosum cut (epilepsy treatment)! No communication between hemispheres! Second slide:! 1. Show apple to right visual field! Patient says apple! 2. Show apple to left visual field! Patient says nothing or lies! Patient can point at an apple, but can t say apple! Message not relayed to language centers! 28! Split Brain Experiments 4! Verbal! Hemisphere! Verbal! Hemisphere! Patient says apple.! Patient can t say what was seen.! 29! Origins of the Cranial PLAY! 30! 10!
Cranial Nerve Table 14-4 (part 1)! 31! Cranial Nerve Table 14-4 (part 2)! See handout on Cranial Nerve assignment on website.! 32! Cranial Nerve Assignment! Information for Cranial Nerves (80 points) Please carefully read what you do and what you do not have to include in order to ace this exam. If you are not using Martini s 10 th edition, get a copy of Table 14-4, page 502 from a student who is and use the copy for this exercise. You are responsible for the information in that table as outlined below, not everything about cranial nerves that can be found on the internet. Table 14-9 Cranial Nerve Branches and Functions For each of the cranial nerves, you will need to be able to provide: 1. the nerve s Roman numeral. 2. the nerve s name. 3. the nerve s branches, if any. 4. the nerve s primary function(s). (Special sensory, sensory, motor and proprioception, or mixed.) 5. the opening(s) (foramina) in the cranium through which the nerve passes. 6. the nerve s innervation: I.e., its effector(s) if it has a motor function or the location(s) of its dendritic endings/receptors if it has a sensory function. Note: If a nerve has branches (e.g. trigeminal nerve), provide numbers 4, 5 and 6, above, for each branch. With the two exceptions listed below, Table 14 4 on p. 502 contains everything that you need to know to earn 100% this exam. The text and drawings on pp. 492 501 are useful for understanding what is being said in the table. 1. If the table indicates that a cranial nerve or nerve branch is motor, then it actually also carries proprioceptive information. You should indicate this (i.e. write motor and proprioception or M and P ) on your exam. 2. You DO NOT need to include any sensory ganglia for any of the nerves on your exam. The exam: You will be given a blank piece of paper and will enter all of the above information. I may ask you to list the nerves in some particular order. (e.g. I, III, V, VII, IX, XI, II, IV, VI, VIII, X, XII). We can discuss some strategies for doing this. 33! 11!