A sketch of the central nervous system and its origins G E Schneider 2009 Part 5 Differentiation of the brain vesicles MIT 9 14 Class 12 Forebrain of mammals with comparative studies relevant to its evolution The forebrain prosencephalon Topics Major subdivisions and overview of tweenbrain Hypothalamus and epithalamus related to limbic system structures of the forebrain Thalamus and subthalamus related more to somatic sensory and motor systems Origins and course of 2 major pathways related to somatic sensory motor systems and limbic system Evidence concerning forebrain evolution Also Review of neuroanatomy covered thus far Rostral end of the thickening neural tube a few more descriptive terms DVR Forebrain LG MG Thickened Ventricular Layer DVR Dorsal Ventricular Ridge LG Lateral Ganglionic Eminence MG Medial Ganglionic Eminence Midbrain Hindbrain Preview Evidence on endbrain evolution Recent data has come from studies of expression patterns of regulatory genes like the hox genes in various species Prior to these studies cross species comparisons were made using only morphological data cytoarchitecture connections patterns dc dorsal cortex Dorsal st striatum Medial cx st s Lateral dc Ventral s am st Mouse Frog dc h dvr dvr s septum h hyperstriatum dvr dorsal ventricular ridge s st st Chick am amygdala claustrum Turtle Homeobox gene expression Archetypal Embryonic Stage Emx 1 Figure by MIT OpenCourseWare Dlx 1 Evolution of telencephalon based on expression patterns of regulatory genes during developmentBased on work of Anibal Smith Fernandez et al figure from Allman 2000 p 113 We will return to these pictures of the endbrain at the end of this section First Major features of the forebrain structure and then a pause for a brief review of major concepts in brain anatomy Forebrain prosencephalon endbrain telencephalon tweenbrain diencephalon The forebrain prosencephalon Major subdivisions and overview Diencephalon Hypothalamus and epithalamus Thalamus and subthalamus Telencephalon Pallium Limbic Non limbic neocortex Corpus striatum Ventral limbic Dorsal non limbic Origins and course of 2 major pathways Diencephalon 1 Hypothalamus epithalamus Visceral inputs Connections with endbrain and midbrain Limbic system connections Functions include gating of pathways ascending through thalamus Diencephalon 2 Thalamus subthalamus dorsal thalamus ventral thalamus Somatic inputs from the lemniscal pathways Connections from midbrain tectum and tegmentum somatic parts of midbrain Somatic regions Limbic regions The forebrain prosencephalon Major subdivisions and overview Diencephalon Hypothalamus and epithalamus Thalamus and subthalamus Telencephalon Pallium Limbic cortex Non limbic cortex neocortex Corpus striatum pallidum Ventral Dorsal Origins and course of 2 major pathways Telencephalon major structures Neocortex Primary sensory and motor cortical areas Unimodal association cortex Heteromodal association cortex Limbic cortex Olfactory cortex Paleocortical closely related structures Corpus striatum Dorsal striatum sometimes called neostriatum Ventral striatum structures including Olfactory Tubercle Globus pallidus ventral pallidum output structures of the striatum The forebrain prosencephalon Major subdivisions and overview Diencephalon Hypothalamus and epithalamus Thalamus and subthalamus Telencephalon Neocortex Corpus striatum Limbic endbrain Origins and course of 2 major pathways Tween brain Fibers of medial lemniscus to VP from Cb to VA VL and Endbrain Olfactory cortex Let s look at these sections one at a time Tweenbrain diencephalon Fibers of medial lemniscus to VP from Cb to VA VL Fibers of Lateral Forebrain Bundle Endbrain telencephalon Olfactory cortex Origins and course of 2 major pathways Lateral forebrain bundle to and from Corpus striatum Neocortex via Neocortical white matter Outputs of neocortex via Internal capsule Cerebral peduncle Pyramidal tract See following slide Medial forebrain bundle to and from Olfactory cortex Limbic cortex Subcortical limbic structures amygdala basal forebrain lateral hypothalamic area limbic midbrain areas Forebrain endbrain tweenbrain the lateral forebrain bundle Corticospinal tract Pyramidal tract Cerebral peduncles includes corticopontine Cortical white matter Internal capsule REVIEW Somatic regions Limbic regions MFB REVIEW Tween brain and Endbrain limbic MFB Lateral forebrain bundle Medial forebrain bundle Lateral forebrain bundle Medial forebrain bundle The neocortex is involved in both major systems A schematic summary Some Major Endbrain Connections Neocortex Dorsal striatum Limbic structures Hypothalamus Brainstem Spinal cord This leaves out a great many details E g in the diagram the ventral striatum is lumped together with limbic structures Ventral striatum is critical in habit formation and is probably the most primitive part of the corpus striatum in evolution Reward and punishment mechanisms exist with a special role of ascending projections e g from taste and pain systems Next picture The schematic summary is augmented Some Major Endbrain Connections Neocortex Dorsal striatum Ventral Thal striatum Limbic structures Hypothalamus Brainstem Spinal cord Striatum dorsal ventral includes the output structures the pallidum dorsal ventral Check your knowledge Neuroanatomy review Subdivisions of CNS definitions of cell types Shapes of the neural tube at various levels Sensory channels of conduction dermatomes Diaschisis lesion produced deafferentation causes a functional depression of neurons Evolution of neocortex with major ascending and descending pathways to it and from it Spinal cord structure differences between levels Propriospinal system Autonomic N S its components Hindbrain organization distortions of the basic plan Cranial nerves the 5th trigeminal nerve Neuroanatomy review continued Midbrain tectum and tegmentum species differences outputs for three major types of movement Diencephalon two major and two additional subdivisions functional structural Telencephalon the endbrain cerebral hemispheres and basal forebrain origins of two major pathways for descending axons Both contain some ascending axons also Some major axonal pathways in mammals Spinoreticular trigeminoreticular tracts mostly ipsilateral Spinothalamic tract longest axons to ventrobasal nuc of thalamus VB VPM and VPL Dorsal columns connecting to the medial lemniscus pathway which projects to the ventrobasal nuc of thalamus Corticospinal corticopontine pathways the former