Neuroscience Week 3
Neuroscience Week 3 PSYC 6
Popular in Introduction to Neuroscience
Popular in Psychology (PSYC)
This 11 page Class Notes was uploaded by Sabrina Straus on Wednesday September 28, 2016. The Class Notes belongs to PSYC 6 at Dartmouth College taught by Catherine Cramer in Fall 2016. Since its upload, it has received 6 views. For similar materials see Introduction to Neuroscience in Psychology (PSYC) at Dartmouth College.
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Date Created: 09/28/16
1. 09-26-16 Intro to Neuro class notes NEUROANATOMY ~various parts of the brain evolution highly conserved features-dendritic tree vertebrate features-optic tectum, olfactory bulb, cerebral hemisphere, cerebellum } just proportions change niche-specific specializations:source of variation depending on natural selection and evolution embryonic development: plate -> groove -> folding -> neural tube -> spinal cord orientation terms Anterior-front / rostral Posterior- tail Dorsal- top Ventral- bottom Medial- midline divides left and right } close Lateral- far from mid line Proximal-close to Distal- far from horizontal plane- separates top from bottom sagittal plane-left and right coronal plane- separates front from back central nervous system-brain + spinal cord - nucleus } cell bodies where integration occurs Tract: projection area peripheral nervous system-everywhere else - ganglia nerves Ventricles-fluid filled/ exchange fluid Lateral:left and right Third fourth cerebrospinal fluid dura mater-thin membrane that covers brain and protects it (has some cerebrospinal fluid) Major subdivisions of the brain: Myelencephalon-first to develop/medulla Metencephalon- pons+cerebellum mesencephalon-midbrain diencephalon Telencephalon-expanded particularly in humans Areas of the brain: cerebral cortex (neocortex) sulcus (e.g., central sulcus) : crease Central sulcus divides precentral gyrus from post gyrus (e.g., precentral gyrus and postcentral gyrus) : ridge frontal lobe temporal lobe parietal lobe occipital lobe : visual optic nerve/chiasm/tract pituitary gland : releases hormones under control of the brain brainstem cerebellum pons medulla corpus callosum - links left and right diencephalon thalamus hypothalamus midbrain superior and inferior colliculus (tectum) limbic system (outer) : generates emotional response } regulated by cortex hippocampus-learning Amygdala-emotional behavior on tip of hippocampus basal ganglia : initiation and control of movement (inner) spinal cord: white matter (white because of myelin-> long axons send info across distance) around grey matter (cell bodies and integration) } input (dorsal) output (motor w/ ventral roots) system dorsal horn and roots ventral horn and roots peripheral nervous system cranial nerves - inputs from the face autonomic nervous system - innervates lots of organs throughout the body } helps w/ subconscious actions sympathetic branch parasympathetic branch nucleus ganglion tract nerve grey matter white matter Chapter Notes Chapter 7: The Structure of the Nervous System -Gross organization of the mammalian nervous system >central >peripheral ● Anatomical references ○ anterior/ rostral : toward nose ○ Posterior/ caudal: tail ○ Dorsal: pointing up (back) ○ Ventral: pointing down (stomach) ○ Right side=left side } bilateral symmetry separated by midline -> midsagittal plane after separation (sagittal plane: sections parallel to the midsagittal) ■ Close to middle = medial ■ lateral= farther away ○ Ipsilateral: two structures on the same side ○ Contralateral: opposite ● Central nervous system: brain and spinal cord ○ Cerebrum: rostral-most+largest part of brain ■ Right: receives sensations and controls movements of the left ■ Left: concerned with the right side ○ Cerebellum: located behind cerebrum/ movement control center (left side is concerned with movements of the left and right with right) ○ Brainstem: relay info from the cerebrum to the spinal cord and cerebellum + vital functions are regulated ○ Spinal cord: encased in bony vertebral column / conduit of info from skin, joints, and muscles to the brain ■ Spinal nerves: help the spinal cord to communicate with the body ● Part of peripheral system ● Attaches to cord by dorsal (brings info in) or ventral root (carry info out) ● Peripheral nervous system ○ Somatic:All the spinal nerves that innervate the skin, the joints, and the muscles that are under voluntary control ■ Motor axons, sensory axons (enter via dorsal roots) ● Dorsal root ganglia: cell bodies of neurons that lie outside spinal cord in clusters ○ Visceral/ involuntary, vegetative, autonomic nervous system: consists of the neurons that innervate the internal organs, blood vessels, and glands ■ axons bring information about visceral function to the CNS ■ Motor fibers command the contraction and relaxation of muscles (that line the intestines and blood vessels = smooth), the rate of cardiac muscle contraction, and the secretory function of various glands ○ Afferent and efferent axons ■ Afferent: carry to } somatic or visceral sensory axons ■ Efferent: carry from ● Cranial nerves: ○ Arise from brainstem and innervate from head ● Meninges:three layers of membrane that encase the skull and vertebral ○ Dura mater: outer layer ○ Arachnoid membrane: where hematomas occur if blood vessel pops ○ Pia mater: separated from arachnoid by subarachnoid space ■ Filled with cerebrospinal fluid ● Ventricular system:fluid filled caverns and canals ○ CSF: fluid made by choroid plexus (flows ventricles to cavities) ■ exits the ventricular system ■ enters the subarachnoid space by way of small openings, or apertures, located near where the cerebellum attaches to the brain stem ■ Absorbed by blood vessels @ arachnoid villi ● New views of the brain-clairify w/ gfp ○ Imaging the structure of the brain:computed tomography ■ Revealed gross organization of gray and white matter, and the position of the ventricles, in the living brain. ■ MRI: uses magnetic field to construct a map of the brain / diffusion tensor imaging enables visualization of large bundles of axons ○ Functional brain imaging: detect changes in blood flow and metabolism within the brain ■ Positron emission tomography ■ Functional magnetic resonance imaging -Understanding CNS structure through development of tube to ventricular system Terms >Gray matter: A generic term for a collection of neuronal cell bodies in the CNS. When a freshly dissected brain is cut open, neurons appear gray. >Cortex: Any collection of neurons that form a thin sheet, usually at the brain’s surface. Cortex is Latin for “bark.” Example: cerebral cortex, the sheet of neurons found just under the surface of the cerebrum. >Nucleus: A clearly distinguishable mass of neurons, usually deep in the brain (not to be confused with the nucleus of a cell). Nucleus is from the Latin word for “nut.” Example: lateral geniculate nucleus, a cell group in the brain stem that relays information from the eye to the cerebral cortex. >Substantia: A group of related neurons deep within the brain but usually with less distinct borders than those of nuclei. Example: substantia nigra (from the Latin for “black substance”), a brain stem cell group involved in the control of voluntary movement. >Locus (plural: loci): A small, well-defined group of cells. Example: locus coeruleus (Latin for “blue spot”), a brain stem cell group involved in the control of wakefulness and behavioral arousal. >Ganglion (plural: ganglia): A collection of neurons in the PNS. Ganglion is from the Greek for “knot.” Example: the dorsal root ganglia, which contain the cell bodies of sensory axons entering the spinal cord via the dorsal roots. Only one cell group in the CNS goes by this name: the basal ganglia, which are structures lying deep within the cerebrum that control movement. >Nerve A bundle of axons in the PNS. Only one collection of CNS axons is called a nerve: the optic nerve. >White matter: A generic term for a collection of CNS axons. When a freshly dissected brain is cut open, axons appear white. >Tract: A collection of CNS axons having a common site of origin and a common destination. Example: corticospinal tract, which originates in the cerebral cortex and ends in the spinal cord. >Bundle: A collection of axons that run together but do not necessarily have the same origin and destination.Example: medial forebrain bundle, which connects cells scattered within the cerebrum and brainstem. >Capsule: A collection of axons that connect the cerebrum with the brain stem. Example: internal capsule, which connects the brain stem with the cerebral cortex. >Commissure: Any collection of axons that connect one side of the brain with the other side. >Lemniscus: A tract that meanders through the brain like a ribbon. Example: medial lemniscus, which brings touch information from the spinal cord through the brain stem. ● Formation of neural tube: ~embryo ○ Endoderm-lining of internal organs ○ Mesoderm -bones + muscles ■ Forms somites-> spinal column ○ Ectoderm-nervous system + skin ■ Neural plate-> neural groove -> neural folds which form neural tube-> } neurulation evolving into the entire central nervous system (some neural ectoderm is pinched off~neural crest~forms peripheral nervous system) ● 3 brain vesicles ~differentiation: structures become more complex and specialized 1. Development @ rostral end of neural tube of primary vesicles a. Prosencephalon: rostral-most vesicle } forebrain b. Mesencephalon } midbrain c. Rhombencephalon } hindbrain connects w/ caudal neural tube to give rise to the spinal cord 2. Differentiation of forebrain: optic vesicles and telencephalic vesicles sprout off and leave diencephalon-> optic nerves and retinas a. Differentiation of telencephalon and diencephalon i. telencephalon: ● Grow posteriorly ● Rise of olfactory bulbs ● Cells of walls divide and differentiate ● White matter develops ~lateral ventricles: fluid-filled spaces within cerebral hemispheres ~third ventricle: space @ center of diencephalon ● Gray matter ○ Cerebral cortex ○ Basal telencephalon ● Differentiates ○ In thalamus ○ In hypothalamus ● axons of forebrain ○ Cortical white matter: contains all the axons that run to and from the neurons in the cerebral cortex ○ Corpus callosum: forms an axonal bridge that links cortical neurons of the two cerebral hemispheres ○ Internal capsule: links the cortex with the brainstem, particularly the thalamus ● Forebrain structure-function relationships ○ Cerebral cortex: Cortical neurons receive sensory information, form perceptions of the outside world, and command voluntary movements} lot of evolution ■ Thalamus: gateway -> communicate with axons in capsule ○ Hypothalamus: not evolved much / controls visceral nervous system } fight or flight, need to eat, and need for sex ● Differentiation of midbrain ○ Dorsal -> tectum ○ Floor -> tegmentum ○ CSF filled space -> cerebral aqueduct ○ Structure-function ■ Conduit for info passing from spinal cord to forebrain ■ Contains neurons that contribute to sensory systems, the control of movement, etc. ■ Tectum ● Superior colliculus: receives direct input from the eye=optic tectum ● Inferior colliculus:receives direct input from the ears ● Nigra+nucleaus that control movement ● Differentiation of hindbrain: ○ Developed from rostral half ■ Cerebellum-formed from rhombic lip ■ Pons ○ Developed from caudal half ■ Medulla oblongata -> medulla pyramids ○ CSF filled tube: fourth ventricle ○ Structure and function: conduit between forebrain and spine + help process sensory info, control voluntary movement, and regulate autonomic nervous system ■ Cerebellum Receives massive axonal inputs and pons ■ Spinal cord gives info about body location ■ Pons give goal of signal}connect cerebral cortex to cerebellum ■ Cerebellum: calculates the sequences of muscle contractions that are required to achieve the movement goals ■ Decussation: crossing of axons from one side to another ● Differentiation of the spinal cord ○ Spinal canal: forms with expansion of tissue and the constricting cavity of the tube ○ Dorsal horn:upper part of gray matter ○ Ventral horn: lower part (comes after intermediate zone) ○ Dorsal column: axons running along the dorsal surface of the cord ○ Lateral columns: bundles of axons lateral to the spinal gray matter on each side ○ Ventral columns: ventral surface ○ Spinal cord structure and function: ■ Horn: receives inputs from dorsal root fivers ■ Ventral: project axons into ventral roots ■ Intermediate zone: shape motor outputs ■ Dorsal: contain axons tha carry somatic sensory info up spinal cord toward brain ■ Lateral: contains axons of descending corticospinal tract ● Putting pieces together ● Special features of Human CNS ○ Similarities: The dorsal view of both brains reveals the paired hemispheres of the telencephalon + A midsagittal view of the two brains shows the telencephalon extending rostrally from the diencephalon->surrounds the third ventricle, the midbrain surrounds the cerebral aqueduct, and the cerebellum, pons, and medulla surround the fourth ventricle. Notice how the pons swells below the cerebellum, and how structurally elaborate the cerebellum is. ○ Differences: ■ Grooves: sulci ■ Bumps: gyri -Guide to Cerebral cortex >cell bodies arranged in layers lying parallel to the surface >layer closest to surface is separated from the pia mater by a neuron-less zone } molecular layer >at least one cell layer contains pyramidal cells that emit large dendrites, called apical dendrites, that extend up to layer I, where they form multiple branches. ● Types of cerebral cortex ○ Hippocampus: Medial to the lateral ventricle is a piece of cortex that is folded onto itself in a peculiar shape ○ Olfactory cortex: Connected to the hippocampus ventrally and laterally / has only two cell layers ■ Separated by sulcus } rhinal fissure ○ Neocortex: only in mammals ■ Areas of neocortex: 17-visual (receives signals from nucleus of thalamus connected to eye), 4-motor (neuron project axons to motor neurons of ventral horn to command muscles) ○ Neocortical evolution and structure-function: ■ Connectome: wiring diagram of connecting neurons ■ Brodmann proposed neocortex expanded by insertion of new areas ● Primary sensory areas ● Secondary sensory areas ● Motor neurons ● Association areas of cortex