BISC 421 1st Edition Lecture 15 Outline of Current LectureI. Cerebellum Current LectureCerebellum•How do we know what structures do? We don't know but one good way to get a sense of what they do is to look at what happens from damage of the structure•A list of things that happen if your cerebellum doesn't work•Nystagmus-‐ jerky eye movementsBase of the brain, ventralSagittal section of brain, right sideBase of the cerebellum, brainstem cutDissection showing fibers paths from the cerebellumCerebellum and spinal cord, dorsal•Ventral view of cerebellum complicated structure•Cerebellum isn’t divided neatly into two halves along the midline although it is bilateral•Folds of cerebellum are very small•Each fold is called a folium•Arbor vitae is the white matter moving into each fold•Divided into zones: cerebrocerebellum, spinocerebellum, vestibulocerebellum•Cerebellum gets bigger and bigger as we evolve•1. Cerebrocerebellum: largest part, most associated with the cerebralcortex. No division, seamless-‐ most lateral zone. Newest and receives input from the contralateral cerebral cortex (remember). Most involved with regulating speech•2. Spinocerebellum: more towards the midline. Older than the cerebrocerebellum. Has somatotopic organization and regulates distal muscles (nearer your digits)•3. Vestibulocerebellum: underneath and sticking a little bit out-‐ the oldest and regulates posture and balance•Cerebellar cortex made of folia•Cerebellar cortex with one exception doesn't extend outside the cerebellum•Need to know all of these slides•Dentate: big circles in the middle-‐ projects to the contralateral premotor cortex for planning movement•Interposed: executing movement in the upper motor neurons in MOTOR CORTEX•Fastigial: projects to upper motor neurons in BRAINSTEM and is involved in executing movement•Motor cortex is home to upper motor neurons•Don't need to know fancy names of anything•Superior peduncle: eferent pathway of fibers exiting from the deep cerebellar nuclei•Middle peduncle: aferent pathway of cortex to the pons to the cerebellum (arriving)•Inferior peduncle: smallest, mixed of aferent from brainstem and spinal cord andeferent from the vestibulocerebellum•Structures associated with the cerebellum•Premotor cortex and motor cortex•Motor thalamus, nuclei in the pons•Inputs to the cerebellum: remember cortex pathways coming down on the ipsilateralside of the body to the pons and carry the information to the contralateral side of the cerebellum through the middle peduncle.Outputs from cerebellum: these pathways will ultimately make their way through the thalamus to the cortex•Don't need to know about red nucleus•Descending outputs of cerebellum: won't go over in great detail•Just need to remember what is on the slides•Each little folium is made of these three layers•Most important cells in the cerebellum are the purkinje cells-‐ very thin layer•Granular cell layer is very dense•The dendritic arbor is very planar•Granule cells hardly have any dendrites at allClimbing fibers convey input from the inferior olive. Each Purkinje cell receives input froma single climbing fiber from the inferior olive (which receives input from the cerebral cortex,spinal cord and red nucleus). Purkinje cell fires a complex spike* in response to input from aclimbing fiber.Mossy fibers come from the pontine nuclei (which relay input from the cerebral cortex,spinal cord and vestibular nuclei) and synapse with granule cells. Each Purkinje cell receiveshundreds of thousands on inputs from parallel fibers. Purkinje cells fire "simple" spikes inresponse to input from parallel fibers•Same sort of picture from book•Need to know parallel fibers•The cerebellar circuit•Know what is on this slide •Purkinje cell always fires if it is infuenced by a climbing fiber but it takes many parallel fibers for the purkinje cell to fire•Alternating firing and not firing that times movement•Helped distinguish the role of the cerebellum in motor learning •VOR coordinates the movement of eye muscles with the movement of head to compensate for that movement •Eventually if you keep the monkey wearing glasses he will learn to move his eyes the right distance to compensate for the head movements-‐ do this all the time with glasses •Diferent pathways in the cerebellum are involved in motor learning•Schematic diagram to help link everything in terms of purpose • Basal ganglia are connected with the
View Full Document
Unlocking...