Week 1 - Neuroscience Introduction PDF

Week 1 Introduction to Neuroscience OT 514 Fall 2024  Introduction to Neuroscience It is a branch of science that deals with the anatomy, physiology, biochemistry, pharmacology and pathology of the nervous system. There are many different approaches...

Week 1 Introduction to Neuroscience OT 514 Fall 2024  Introduction to Neuroscience It is a branch of science that deals with the anatomy, physiology, biochemistry, pharmacology and pathology of the nervous system. There are many different approaches to understanding and analyzing the nervous system.  What does neuroscience have to do with becoming an OT? List 2 reasons why you think taking this course will be useful to you as an OT. 1. 2.  Terminology Superior/inferior: above/below another part Ventral/dorsal: toward the front (belly)/back Anterior/posterior: toward the front/back Rostral/caudal: toward the head/tail It is like learning a new language! Superior view of Inferior view the brain of the brain  Terminology Medial/lateral: toward/away from the midline Proximal/distal: nearest/farthest from the point of origin Ipsilateral/contralateral: same/opposite side of the body – Brain control? Organization of the brain: topographic/somatotopic  Topographic Organization Neurons responsible for the same function are all located closely together  Somatotopic Organization Visual representation of the body on the brain (“homunculus”)  Other Terminology Somatic/visceral: body/organs Afferent/efferent: – Afferent: carries sensory information from skin/muscles to SC – Efferent: Carries motor information from spinal cord towards the muscles/glands/organs Lesion: an area of damage or dysfunction  Planes Coronal (frontal): divides into anterior & posterior sections Sagittal: divides into right & left portions Transverse (horizontal): cuts at a right angle to the long axis of the structure Coronal (frontal) section Sagittal section Transverse (horizontal) section Cellular Level Two major types of cells in the nervous system: – Neurons – Glial cells  Neuron The basic functional unit of the nervous system. The neuron has 4 major components: 1. Cell body (soma) 2. Dendrites 3. Axon 4. Synaptic terminals  Neuron Cell body (soma) Metabolic center Receives and integrates information Axon hillock Dendrites Receives information, main input site of the cell Increases the receptive surface of the neuron  Neuron Axon Sends information to other neurons, main output unit Arises from the axon hillock Group together and form nerves and tracts Presynaptic terminal Specialized areas at distal axon Release neurotransmitters into the synaptic cleft  Glial Cells Functions: ○ Provide structural support (surround, support, separate neurons) ○ Provide electrical insulation (form myelin) ○ Scavengers ○ Important in development  Microglia Immune system of the CNS Clean the neural environment o Phagocytes (clean up and remove debris from dying cells) Activated: o During NS development o Following injury, infection, or disease  Macroglia Astrocytes (CNS) o Clean the neural environment o Part of the blood brain barrier o Connect neurons and blood capillaries, providing nutrition to neurons o Can regulate neuronal communication Oligodendrocytes (CNS) & Schwann cells (PNS) o Form myelin to insulate axons  CNS: oligodendrocytes  PNS: Schwann cells  Stem Cells Mature neurons cannot reproduce Stem cells: undifferentiated cells o Self-renew o Differentiate into most type of neurons and glial cells o Populate developing and degenerating regions of the CNS  Gray and White Matter Gray matter = cell bodies o Integrates information o CNS: nuclei (cortex; horn) o PNS: ganglia White matter = axons & myelin o Conveys information o CNS: tract, fasciculus, column, peduncle, lemniscus, capsule o PNS: nerve Gray and White Matter Gray and White Matter  Development of the Nervous System Nervous system development in-utero starts with the formation of the neural tube. Two phases of the Embryonic Stage (Day 15- end of 8th week): 1. Neural tube formation (Day 18- 26) 2. Brain formation (Begins Day 28)  Neural Tube Formation After fertilization, there is multiplication of cells, which leads to the formation of an embryo (3 layers). A portion of the outer layer of the embryo (ectoderm), thickens to form a structure called the neural plate. The edges of the neural plate fold to form the neural groove (day 18). When the edges touch (day 21), the neural tube is formed. The cells adjacent to  Closure of the Neural Tube Superior neuropore closes first (by day 27) and the inferior neuropore closes ~3 days later. The tube differentiates into two concentric circles (by day 26) Inner layer becomes gray matter of SC Outer layer white matter of SC.  Spinal Cord Vertebral column: 33 segments Spinal cord: travels through the vertebral column; 31 pairs of spinal nerves arises from each segment ○ Conus Medullaris ○ Cauda Equina  Spinal Cord - Function Conduit for flow of information to and from the brain Control of limb and trunk muscles Cervical Thoracic Lumbar Sacral Processing of information Development of the brain (starts Day 28) Brain formation begins when the superior neuropore closes  Brainstem Connects the spinal cord and cerebrum; integrates information and regulates vital functions ○ Medulla ○ Most caudal end ○ Life support centers ○ Pons ○ Rostral to medulla ○ Regulates respiration; bridge to cerebellum ○ Midbrain ○ Most rostral section of  Cerebellum Purpose: – Coordination of movement – Controls range and force of movement – Balance – Motor learning/memory Located caudal to the cortex, posterior to the brainstem  Diencephalon Caudal to the cortex, superior to the brainstem Includes: o Thalamus o Hypothalamus o Epithalamus o Subthalamus  Diencephalon: Thalamus Constellation of nuclei that relays almost all information to the cerebral cortex Integrates sensation Processes emotional information Involved in memory Regulate consciousness, arousal, & attention  Diencephalon: Hypothalamus Homeostasis Regulation of visceral and endocrine functions o Eating, reproduction, motivation behaviors o Regulation of circadian rhythm o Endocrine regulation of growth, metabolism etc.  Sulci, Gyri, and Fissures The cortex is not smooth, but rather has bumps and grooves Sulci, gyri, and fissures separate the cerebral cortex into lobes and hemispheres o Gyrus: bump/ridge o Sulcus: groove/valley o Fissure: deep groove  Major Sulci/Fissures Central sulcus: divides the frontal and parietal lobes Sylvian/Lateral fissure: divides the frontal and parietal lobe from the temporal lobe Medial longitudinal fissure: divides right and left hemispheres  Major Gyri Precentral gyrus: anterior to the central sulcus (most posterior aspect of the frontal lobe) Postcentral gyrus: posterior to the central sulcus (most anterior aspect of the parietal lobe)  Telencephalon Largest part of the brain Consists of the two cerebral hemispheres  Telencephalon: Cerebral Hemispheres 2 cerebral hemispheres are connected. Each hemisphere is divided into 4 lobes: o Frontal o Parietal o Temporal o Occipital  Frontal Lobe Control of movement Personality Executive functions (planning, self- monitoring, judgment, etc.). “M1” = primary motor cortex (precentral gyrus)  Parietal Lobe Sensory Perception Body image/schema Spatial awareness “S1” = primary somatosensory cortex (postcentral gyrus)  Temporal Lobe Hearing Speech comprehension Memory Aspects of learning  Occipital Lobe Vision  Telencephalon: Basal Ganglia Nuclei located deep within the cerebral hemispheres. Functions: o Initiation and control of movement o Cognition and emotion Telencephalon: Limbic system Nuclei located deep within the cerebral hemispheres. – Hippocampus – Amygdala Functions: o Memory, learning, emotion, motivation Supports of the Nervous System Two systems support the neurons and glial cells of the nervous system ○ Vascular system ○ Cerebrospinal fluid (CSF) system  CSF  Ventricles: 4 CSF filled spaces inside the brain  Meninges: connective tissue surrounding the brain and spinal cord; protective; also circulatory functions Ventricles & Cerebrospinal Fluid (CSF) CSF flows through ventricles and around the spinal cord in a unidirectional manner ○ Functions of CSF: Helps maintain homeostasis Shock absorber Fluid transport system  Meninges Three layers ○ Dura mater: Outer layer, tough Surrounds brain & spinal cord ○ Arachnoid mater: Middle layer, delicate Loosely attached to dura mater Subarachnoid space ○ Pia mater: Innermost layer, very delicate Tightly adheres to brain & spinal cord Meninges  Neuroplasticity Neuroplasticity: the ability of neurons to change their function, chemical profile, and/or structure o Involved in: o Habituation o Learning and memory (experience- dependent neuroplasticity) o Recovery after injury o Maladaptation after injury  Post-Natal Development “Critical periods” of development Periods of time when the nervous system optimizes neural connections Crucial for typical development: experience is the chief architect of the brain (“use it or lose it”) Post-Natal Development: Adolescent Years Adolescent brain is not finished developing! Growth spurts with proliferation and pruning, particularly in prefrontal cortex. What teenagers do matters!  Aging & the Brain In typical aging: – Anatomical changes: Cortex thins White matter decreases Neurotransmitter/receptor changes – Functional changes E.g., sensation, motor skills, speed, memory, vision Factors can slow or hasten these changes: – Weight, Exercise, Rest, Stress Important Terminology for Clinical Correlates Etiology: cause/origin of a disease or abnormal condition Pathology: what is actually happening in the body Prognosis: the prospect of recovery from disease  Clinical Correlates: Anencephaly Etiology: chromosomal abnormalities, maternal nutritional deficiencies, maternal hyperthermia Pathology: superior neuropore does not close; forebrain does not develop and skull/skin does not form over incomplete brain Prognosis: most fetuses die before birth, almost none survive longer than a week following birth  Clinical Correlates: Spina Bifida Etiology: maternal nutritional deficiencies Pathology: inferior neuropore does not close; vertebrae do not close around the incomplete neural tube Symptoms: varies based on location and severity of malformation (e.g., sensory & motor impairment of lower limbs, bowel/bladder difficulties, intellectual disability) Prognosis: impairment is usually stable Clinical Correlates: Hydrocephalus Etiology: congenital or acquired Pathology: buildup of CSF in the ventricles causes enlargement of ventricles, compressing brain tissue Symptoms: enlarged head (fetus/infant); impairments in balance, gait, bladder control, executive functions (e.g., emotions, planning memory, etc.) Clinical Correlations: Meningitis Etiology: usually viral infection Pathology: inflammation of meninges Symptoms: headache, fever, confusion, vomiting, neck stiffness Prognosis: viral meningitis rarely life threatening; bacterial meningitis is rare but potentially fatal.