Lecture 1 outline 2024_merged.pdf

Lecture 1 Outline Aug 29, 2024 John Kubie Readings: chapter 5, p. 47-55 p 67: “brain vesicles”...

Lecture 1 Outline Aug 29, 2024 John Kubie Readings: chapter 5, p. 47-55 p 67: “brain vesicles” p. 77-9: “ventricles” I. Domain of the CNS and PNS A. CNS: brain and spinal cord, within cranium and vertebral column. B. PNS: peripheral nervous system C. White matter and gray matter in the CNS II. Brain and Spinal Cord A. Spinal Cord 1. white matter on the outside 2. “H”-shaped gray matter at core a) ventral horn is has motor neurons. enter PNS via ventral root b) dorsal horn has sensory-relay neurons. connect to PNS via dorsal root. c) dorsal root ganglion contains cell bodies of primary sensory neurons. d) sensory and motor axons travel together in peripheral nerves. B. Brain also has white matter and gray matter. 1. Most gray matter on outside. Layered gray is on the outside is ‘cortex’; deep gray matter generally termed ‘nuclei’. 2. Names associated with gray matter include: cortex, nucleus, reticular, tegmentum, gray, body, tubercle, tectum, colliculus. 3. Large amounts of white matter especially in cerebral hemispheres. One important pathway (white matter) is the internal capsule. 4. Names associated with white matter include: capsule, tract, peduncle, pathway, lemniscus, fasciculus, funiculus, III. Neurons and Glia. (brief introduction; covered in lecture 3) A. Neurons 1. Neurons look different with different stains. 2. In slides of cerebral cortex we see the layering patterns of neurons. The analysis of layering is called cytoarchitecture. 3. Cell bodies are microscopic, but axons can travel great distance. B. Glia (astrocytes, oligodendrocytes, ependymal cells, microglia) Glia will be discussed in greater detail in neural cell biology lecture. IV. Basic pattern of brain organization A. Brain and spinal cord are a tube, with the ventricular system the lumen (hollow center of the tube) and the brain substance the walls of the tube. B. Five swellings of the tube that occur during development at the rostral end form the brain. Each swelling is a different part. In general, each swelling is associated with its own swollen lumen, which become the ventricles. V. Although the original tube is a straight line, there is folding. A. The front-most swellings the the largest. They will form the cerebral hemispheres. B. The other 4 enlargements are termed the “brainstem”. C. With growth the cerebral hemispheres fold back and rest upon the brainstem. VI. Specifics of Development, Regional Organization and the Ventricular System A. Brain as a tube B. 3 vesicle stage: forebrain, midbrain hindbrain, (+ spinal cord, which remains a simple tube)  C. 5 vesicle stage: 1. forebrain develops into a) cerebral hemispheres (telencephalon) b) thalamus + hypothalamus (diencephalon) 2. midbrain stays as the midbrain (mesencephalon) 3. hindbrain develops into a) pons + cerebellum (metencephalon) b) medulla (myelencephalon) D. Ventricular system 1. Telencephalon: lateral ventricles (connects to IIIrd ventricle via the interventricular foramen, also called the foramen of Munro) 2. Diencephalon: third ventricle 3. midbrain: cerebral aqueduct 4. pons, cerebellum and medulla: 4th ventricle. 5. Medulla has 2 components: open medulla has 4th ventricle on its dorsal surface. Caudal half of medulla is called “closed medulla”. Not touching the 4th ventricle. 6. Production and flow of CSF: a) produced by choroid plexus. Greatest amount in the lateral ventricles, but also present in the III and IVth ventricles. b) Flows from rostral to caudal. A lot is produced in 1 day: many times the volume of the ventricular system. Flow pattern: lat vent -> IIIrd vent -> cerebral aqueduct -> IVth vent -> subarachnoid space c) Exits ventricular system through 3 foramina in IVth ventricle: two foramina of Luschka and foramen of Magendie. d) CSF in subarachnoid space surrounds and protects the brain. Large regions are called cisterns. Largest, the lumbar cistern, is at the caudal end of vertebral canal. e) Absorbed into venous blood at the superior sagittal sinus through arachnoid granulations. For the rest of lecture 1 and continuing into lecture 2 we will examine the content of the CNS region by region. In lecture 1 we will start with the forebrain. (cerebral hemispheres + thalamus). In lecture 2 we will examine all brain levels and return to a more detailed description of the forebrain. VII. Organization of the forebrain A. Cerebral hemispheres 1. Gray Matter a) Cortex b) basal ganglia 2. white matter a) Internal capsule b) Association Bundles B. Thalamus C. Cortico-thalamic relations D. Types of cortex 1. primary sensory 2. sensory association 3. primary motor 4. motor association 5. other E. Regions of the cerebral hemispheres 1. Parietal lobe a) Primary somatosensory cortex b) sensory association cortex 2. Occipital lobe a) Primary and secondary visual cortex 3. Temporal lobe a) Primary auditory cortex b) sensory association cortex c) Broca’s area d) Limbic structures: hippocampus and amygdala. 4. Frontal lobe a) primary motor b) motor association c) prefrontal (planning, personality) 5. Insula a) ANS, b) pain and interoception.  Lecture 2 and 3 Outline Sept 3 and 6, 2024 John Kubie Readings: Nolte Ch 5: General Organization of the CNS I. Functions and Features of Different CNS Levels A. Telencephalon and Cerebral Hemispheres 1. Cortex: a) neocortex. 6-layered. Only found in mammals. Most human cortex is neocortex. b) allocortex. simpler than neocortex. Hippocampus and olfactory cortex are examples. found in mammals and reptiles. 2. Basal Ganglia: a) caudate. Part of motor control loop. b) putamen. Part of motor control loop. c) globus pallidus. Part of motor control loop. d) claustrum. function not clear. e) nucleus accumbens. part of motor learning circuit, reward and reinforcement. 3. White matter. a) Ascending and descending: internal capsule (1) Ascending: thalamocortical (from thalamus to cortex) (2) descending: cortex to lower parts of brain. Including cortico-spinal. (3) From anterior to posterior, internal capsule composed of anterior limb, genu, posterior limb and retroventricular limb. b) commissural (1) corpus callosum; parts (anterior to posterior): genu, body, splenium. (2) anterior commissure c) Association (cortico-cortical; within one hemisphere); various tracts. 4. Lobes of each cerebral hemisphere a) Frontal. contains primary motor cortex, essential for voluntary motor control. b) Parietal. contains primary and secondary somatic sensory cortex. Essential for skin and body senses such as touch, temperature and pain. c) Occipital. contains visual cortex. d) Temporal. contains auditory cortex and parts of the limbic system, hippocampus and amygdala. limbic system is involved in emotions and memory. B. Diencephalon: thalamus and hypothalamus 1. Third Ventricle; a) midline, adjacent to both thalamus and hypothalamus b) connects with each lateral ventricles via an interventricular foramen (of Monro). 2. Thalamus; a) made up of specific thalamic nuclei (VPL, VPM, lateral geniculate, medial geniculate and others. More on these later) b) 1:1 mapping with cerebral cortex (1) thalamocortical  (2) cortico-thalamic c) the thalamus is a required relay for sensory information to reach the cerebral cortex. It also acts as a “gate” that can turn access to the cortex on or off. 3. Hypothalamus a) Control of ANS and endocrine systems b) Motivation and Emotion c) Homeostatic control (1) regulates the internal milieu C. Mesencephalon 1. Principal Function: Orientation to visual and auditory inputs. 2. Structures: a) superior colliculus (visual information), inferior colliculus (auditory), Each is a region that organizes head-orientation responses. Superior and inferior colliculus together are called the ‘tectum’ (roof). b) red nucleus: output from cerebellum. c) substantia nigra. motor control d) cerebral peduncles. White matter. continuation of internal capsule. Descending axons whose cell bodies are in cerebral cortex. e) midbrain tegmentum. Loose, “reticular” area containing neurons and axons. Between tectum and cerebral peduncles. f) cerebral aqueduct g) central gray. region of gray matter surrounding cerebral aqueduct. h) oculomotor nerve and nuclei. D. Pons and Cerebellum. Pons and cerebellum work together as part of a large loop with motor cortex. 1. Pons is divided into “pontine tegmentum” and “true pons”. 2. Pontine tegmentum. contains tegmentum (reticular organization) and important nuclei for cranial nerves V, VI, VII. Also specific sensory and motor pathways run through the pontine tegmentum. Locus ceruleus is a nucleus within the pontine tegmentum. 3. Gray Matter within Pons: a) vestibular nuclei b) auditory nuclei 4. True pons. Region ventral to pontine tegmentum. Contains nuclei and fibers connecting to cerebellum. 5. Cerebellum. Contains deep cerebellar nuclei and cerebellar cortex. 6. Cerebellar peduncles are major inflow and outflow pathways connecting the cerebellum a) superior: outflow (to thalamus) b) middle: input (indirectly from cortex) c) inferior: sensory inputs. (vestibular and somatosensory) 7. IVth ventricle. Rostral half lies between the pons and cerebellum. E. Medulla 1. Open and closed medulla a) Open Medulla: rostral part; part of medulla that has IVth ventricle on its dorsal surface b) Closed Medulla  2. Emerging Nerves a) cranial nerves VI, VII, VIII, in border with pons b) cranial nerves IX, X, XI and XII 3. Gray matter: a) olives (inferior olivary nuclei). Connect to cerebellum. b) reticular formation c) nucleus of the tractis solitarius. Visceral afferents of cranial nerves VII, IX and X synapse here. This is the first CNS synapse of taste information. d) nucleus ambiguous; nuclei for part of motor output for cranial nerves X and IX. controls muscles of larynx. e) dorsal column nuclei. Relays sensory information transmitted from spinal cord. 4. White Matter a) pyramids. Part of the cortico-spinal motor pathway. b) decussation of the pyramids. Boundary between brain and spinal cord. Site where 90% of the axons in the pyramids cross the midline. c) inferior cerebellar peduncle (see above) d) dorsal columns. Axons transmitting sensory information. Continuations of dorsal columns of spinal cord. Contained axons synapse in dorsal column nuclei. F. Spinal Cord (covered in lecture 1; not in today’s lecture) 1. Dorsal horn, ventral horn, Dorsal columns (fasciculus gracilis and cuneatus), 2. sensory input into dorsal horn 3. motor outflow from ventral horn 4. spinal reflexes 5. ascending and descending pathways in white matter II. Example of a single pathway: the cortico-spinal pathway III. Organizational Patterns — content is highly visual; rely on lecture. A. Cortex, Thalamus and Basal Ganglia (plus some lateral ventricle) B. Internal Capsule and pyramid tract (concept of upper and lower motor neurons) C. Lobes and Gyri D. Brainstem and 4th ventricle E. Lateral Ventricle and Limbic System  Lecture 4 Outline Sept 11, 2024 John Kubie Readings: Nolte Ch 1 (cells) Nolte Ch 6 develop. Nolte pgs 79-82 blood suppl. I. Cells and Tissues of the CNS A.Neurons 1.Basic Components a) axon b) dendrite (1) dendritic shaft (2) dendritic spines c) cell body (soma; perikaryon) (1) nucleus (2) Nissl substance (3) axon hillock 2.Connections a) synapses b) synaptic vesicles c) synaptic transmission d) electrical and chemical signaling e) excitatory and inhibitory synapses f) slow (metabotropic) and fast (ionotropic) post-synaptic effects 3.Types of Neurons a)pyramidal neurons b)bipolar neurons c)Purkinge cells of the cerebellum d)interneurons e) motor neurons f) primary sensory neurons B. Glia (CNS) 1. Astrocyte; a) Nutrition and support. b) Form barriers between CNS and vessels or outside of the brain. 2. Oligodendrocyte a) CNS myelin b) one oligo can myelinate parts of several axons 3. Microglia; 4. Ependymal Cells a) line ventricles b) important component of choroid plexus C. Neuronal Patterns in Cerebral Cortex 1. Neocortex has 6 layers 2. Layer 4 gets input from thalamus 3. Layers 5 and 6 are principal output layers with large, pyramidal cells 4. organized in columns  5. Allocortex is more primitive, 3 layers, no thalamic input, still has pyramidal cells. D. Cerebellar Cortex (Purkinge cells) II. Development A. Normal development 1.Originates from Neural Ectoderm as neural tube. CNS has characteristics of ectorderm 2. Neural Crest, the origin of the PNS, pinches off from the neural tube. 3. Swellings at rostral end create brain. 4. Placodes are regions that pinch off from rostral end and lead to sense organs. 5. Motor regions are ventral and sensory regions are dorsal. 6.Most Neurons are born (final division) before birth B. Abnormal 1. Failure of closure of the caudal end of the tube is spinal bifida. 2. Failure of closure of the rostral end leads to microencephaly. 3. Examples of formation of the spinal cord and medulla. C. Myelination 1.proceeds more slowly than neuronal birth 2. long tracts are not functional until myelinated: for example motor tracts. 3. myelination in the forebrain continues until individuals are in their 20s. 4. Lack of myelination in frontal lobes may be associated with lack of impulse control in adolescents. 5. Increasingly, mental diseases associated with problems in myelination. III. Vessels in CNS A. Arterial Supply 1. All from ventral side of brainstem and hemisphere. 2. vertebral basilar 3. carotid B. Carotid supply to forebrain -> rostral circle of Willis 1. Anterior Cerebral artery a) Comes directly off of the internal carotid. b) 2 run side-by-side above the corpus callosum c) supply medial wall of cerebral hemisphere (except occipital lobe) 2. Middle cerebral Artery a) supplies rostral deep gray (thalamus and basal ganglia) b) supplies lateral aspect of hemisphere 3. Posterior Cerebral Artery a) Supplied by vertebral basilar, not carotid b) supplies inferior surface of cerebral hemisphere. 4. anterior choriodal (no figure) a) supplies deep gray in posterior cerebral hemishere C. Vertebral Basilar supplies Brainstem 1. inferior cerebellar arteries 2. anterior inferior cerebellar arteries. 3. superior cerebellar arteries 4. others D. Venous drainage