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Introduction - Part I - Learning about the brain...

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Unformatted text preview: Learning about the brain Introduction Part I, Week 1 SPA 4930 Stephanie Karidas, M.A. Why study neuroanatomy? Our ability to... perceive (sound, light, taste, smell, touch) think remember pay attention feel emotion make decisions perform actions self-monitor produce speech understand language ...is driven by our... ...nervous system. 2 Neuroscience Our aim is to associate specific neurological landmarks / neurological systems... ...to specific functions (related to speech, language, hearing, swallowing, etc). 3 Today's objectives 1. 2. 3. Review terms for sections & directions Learn about neuroimaging techniques Be able to list the major divisions of the nervous system, the central nervous system, and the seven major components of the cerebrum 4. List the four lobes of the cerebral hemispheres and know at least one important function of each Terms for brain sections Coronal front from back Terms for brain sections Sagittal left from right Terms for brain sections Horizontal (cross section), transverse upper from lower Terms of direction Rostral (towards the head) Caudal (towards the tail) Dorsal (towards the back) Ventral (towards the stomach) Lateral (towards the outside) Medial (towards the inside) Neuroimaging techniques 1. 2. 3. 4. 5. CT MRI & fMRI Angiography PET Brain Mapping/Electrophysiology Structural vs. Functional Imaging Structural imaging: Imaging that can only show the static brain what is there. Functional imaging: Imaging that shows the activity of the brain what areas are active under certain circumstances Structural Imaging: CT X ray beams passing through the body reflect off different densities of tissue, bone and fluid in different ways, producing an image Image produced in a single plane Uses of CT Commonly used; relatively inexpensive Used in clinical settings to detect fluid vs. mass lesions Used in research to uncover relationships between structures (e.g., size) and behavior. CT Examples Epidural hematoma Fluid pressing on brain tissue Structural Imaging: MRI Magnetic Resonance Imaging: Magnetic current is applied Detects distribution of water molecules in living tissue Data collected from three planes or dimensions More sensitive to abnormalities than CT scan Uses of MRI Relatively expensive; used less frequently than CT in medical settings Provides clearer, more detailed view of brain structures Structural Imaging: Angiography Injection of dye (contrast medium) into arteries [radiopaque material which shows up on the X ray] X ray technique which is designed to provide structural images of blood vessels Cerebral angiography relevance to stroke Cerebral angiography carotid arteries vessels of neck leading to brain Functional Imaging: PET Positron Emission Tomography shows the function of the brain based on glucose metabolism. Underlying logic is that brain regions that are active in a task require more energy (glucose, oxygen). A radioisotope is injected that tags onto glucose (invasive) radioactive material Emitted radiation is used to form an image. PET Examples Functional Imaging: fMRI Functional Magnetic Resonance Imaging uses the same magnetic technology as structural MRI Hemodynamic change (increase in blood flow) In contrast to PET scans, this technique does not require injection of contrast (noninvasive), so it is safer for medically compromised patients fMRI Examples: Expertise shows up in the brain Functional Imaging: Electrophysiology Electrophysiological techniques such as EEG and Evoked Potentials can show the temporal dynamics of the neural system Evoked potentials (EP) = electrical potential following stimulus Stimuli can be presented in any modality: visual, auditory, somatosensory, olfactory EP Examples Event-related evoked potentials (ERPs) Functional Imaging: Brain Electrical Activity Mapping Uses electrophysiological techniques Cerebral electrophysiology/ EEG (Electroencephalograph) = ongoing electrical activity of brain regions With multiple electrodes placed around the scalp, provides the opportunity to have localization information about WHERE the response occurs BEAM Example Summary of Functional Imaging Techniques PET fMRI Electrophysiology/ERPs/BEAM Overview of Functional Imaging Techniques Spatial Resolution: The ability with which we can view details of the location of the activity in the brain Temporal Resolution: How quickly we can get information about the course of the response from the time of stimulus presentation Spatial Resolution: From Best to Worst fMRI, fMRA PET Electrophysiological techniques Temporal Resolution: From Best to Worst Electrophysiological techniques fMRI PET Basic Components of the Nervous System Central Nervous System (CNS) = Brain + Spinal cord Peripheral Nervous System (PNS) = Nerves emanating from CNS, and connecting to muscles (spinal nerves + cranial nerves) Components of PNS Spinal nerves Cranial nerves Seven Major Parts of the Brain 1. Cerebrum Two cerebral hemispheres (right hemisphere, left hemisphere) Cortex (cortex = "bark" outer layer of brain tissue) Sulci (sulcus) and gyri (gyrus) Seven Major Parts of the Brain 2. Diencephalon Thalamus Hypothalamus 3. Midbrain (part of brainstem) Composed of sensory motor fibers that pass through pons and medulla Seven Major Parts of the Brain 4. Cerebellum 5. Pons (part of brainstem) 1. Medulla, aka medulla oblaganta (part of brainstem) 2. Spinal Cord (SC) Some literature will also define the Basal Ganglia as a major part of the brain. I will therefore include this structure in the functional portion of these different brain structures. Functions of the Major Components of the Brain Cerebrum: Higher thinking, personality Diencephalon: Relay station (thalamus); regulates basic drives such as hunger, thirst, and temperature control. Midbrain: Mediates auditory and visual reflexes; cranial nerve nuclei Cerebellum: Motor coordination, new learning Pons: Regulates basic body functions Medulla: Regulates respiration, heart beat, blood pressure SC = part of the CNS, protected by vertebral column Basal Ganglia: Regulates motor function Cerebral hemispheres (left and right) Separated by the longitudinal cerebral fissure Connected by the corpus callosum (large structure consisting of white matter) Each hemisphere has four lobes Frontal Parietal Occipital Temporal On the lateral surface of the cerebral hemispheres Sulcus (plural = sulci) = pocket or groove Another name for a groove is fissure Gyrus (plural = gyri) = outgoing tissue We use certain gyri and sulci as landmarks for bordering various areas of the brain We can also identify gyri and sulci as being typically associated with certain functions The Frontal Lobes Most anterior section Inferior boundary lateral sulcus Posterior boundary central sulcus Includes precentral gyrus Aka motor strip This is the primary cortical area for motor control Depicted with homunculus Somatotopic organization Functions of the frontal lobes Premotor or supplementary motor area Prefrontal area Broca's area Posterior 1/3 of the inferior frontal gyrus The frontal lobe subserves motor abilities, motor planning, and executive functions like attention, impulse control The Parietal Lobes Anterior boundary is central sulcus Inferior boundary is lateral sulcus Postcentral gyrus Primary area of sensation Aka sensory strip Somatotopic organization Supramarginal gyrus Angular gyrus Example: Sensory strip Phantom limbs The cortical organization of an individual who has had a limb amputated still includes the amputated limb So, there can still be a perception of that limb, because it is still represented in brain tissue Over time, cortical organization can change to reflect the actual status of the periphery. The Temporal Lobes Superior boundary: lateral sulcus Insula Superior temporal gyrus Heschl's gyrus: Primary cortical area for hearing Posterior portion of the superior temporal gyrus Wernicke's area Primary area for olfaction The Occipital Lobes Smallest of the four lobes Medial surface Parietal-occipital sulcus Calcarine sulcus Primary cortical area for vision Cortical Area Prefrontal Cortex Function Problem Solving, Emotion, Complex Thought Motor Association Cortex (Premotor Area) Coordination of complex movement Primary Motor Cortex Initiation of voluntary movement Primary Somatosensory Cortex Receives tactile information from the body Sensory Association Area Processing of multisensory information Visual Association Area Complex processing of visual information Visual Cortex Detection of simple visual stimuli Wernicke's Area Comprehension of information for language Auditory Association Area Complex processing of auditory information Auditory Cortex Detection of sound quality (loudness, tone) Major brain areas Major brain areas ...
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