PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 12 The Central Nervous System: Part A
Copyright © 2010 Pearson Education, Inc. Central Nervous System (CNS) CNS consists of the brain and spinal cord
Copyright © 2010 Pearson Education, Inc. Embryonic Development Neural plate forms from ectoderm Neural plate invaginates to form a neural groove and neural folds
Copyright © 2010 Pearson Education, Inc. Embryonic Development Neural groove fuses dorsally to form the neural tube Neural tube gives rise to the brain and spinal cord
Copyright © 2010 Pearson Education, Inc. Figure 12.1, step 3 Neural fold cells migrate to form the neural crest, which will form much of the PNS and many other structures. 3 Neural crest
Copyright © 2010 Pearson Education, Inc. (d) Adult brain structures (c) Secondary brain vesicles Spinal cord Cerebellum Brain stem: medulla oblongata Brain stem: pons Brain stem: midbrain Diencephalon (thalamus, hypothalamus, epithalamus), retina Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei) Myelencephalon Metencephalon Mesencephalon Diencephalon Telencephalon Central canal Fourth ventricle Cerebral aqueduct Third ventricle Lateral ventricles (e) Adult neural canal regions Figure 12.2c-e
Copyright © 2010 Pearson Education, Inc. Regions and Organization of the CNS Adult brain regions 1.Cerebral hemispheres 2.Diencephalon 3.Brain stem (midbrain, pons, and medulla) 4.Cerebellum
Copyright © 2010 Pearson Education, Inc. Figure 12.3d Cerebellum Diencephalon Cerebral hemisphere (d) Birth Brain stem Midbrain Pons Medulla oblongata
Copyright © 2010 Pearson Education, Inc. Regions and Organization of the CNS Spinal cord Central cavity surrounded by a gray matter core External white matter composed of myelinated fiber tracts
Copyright © 2010 Pearson Education, Inc. Figure 12.5 Anterior horn Interventricular foramen Inferior horn Lateral aperture (b) Left lateral view Lateral ventricle Septum pellucidum Third ventricle Cerebral aqueduct (a) Anterior view Fourth ventricle Central canal Inferior horn Posterior horn Median aperture Lateral aperture
Copyright © 2010 Pearson Education, Inc. Cerebral Hemispheres Surface markings Ridges (gyri), shallow grooves (sulci), and deep grooves (fissures) Five lobes Frontal Parietal Temporal Occipital Insula
Copyright © 2010 Pearson Education, Inc. Cerebral Hemispheres Longitudinal fissure Separates the two hemispheres Transverse cerebral fissure Separates the cerebrum and the cerebellum PLAY Animation: Rotating brain
Copyright © 2010 Pearson Education, Inc. Figure 12.6a Postcentral gyrus Central sulcus Precentral gyrus Frontal lobe (a) Parietal lobe Parieto-occipital sulcus (on medial surface of hemisphere) Lateral sulcus Transverse cerebral fissure Occipital lobe Temporal lobe Cerebellum Pons Medulla oblongata Spinal cord Cortex (gray matter) Fissure (a deep sulcus) Gyrus Sulcus White matter
Copyright © 2010 Pearson Education, Inc. Figure 12.6b Central sulcus (b) Frontal lobe Temporal lobe (pulled down) Gyri of insula
Copyright © 2010 Pearson Education, Inc. Figure 12.6d Left cerebral hemisphere Transverse cerebral fissure Cerebellum Brain stem (d)
Copyright © 2010 Pearson Education, Inc. Cerebral Cortex Thin (2–4 mm) superficial layer of gray matter Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding Each hemisphere connects to contralateral side of the body There is lateralization of cortical function in the hemispheres
Copyright © 2010 Pearson Education, Inc. Functional Areas of the Cerebral Cortex The three types of functional areas are: Motor areas—control voluntary movement Sensory areas—conscious awareness of sensation Association areas—integrate diverse information Conscious behavior involves the entire cortex
Copyright © 2010 Pearson Education, Inc. Motor Areas Primary (somatic) motor cortex Premotor cortex Broca’s area Frontal eye field
Copyright © 2010 Pearson Education, Inc. Figure 12.8a Gustatory cortex (in insula) Primary motor cortex Premotor cortex Frontal eye field Working memory for spatial tasks Executive area for task management Working memory for object-recall tasks Broca’s area (outlined by dashes) Solving complex, multitask problems (a) Lateral view, left cerebral hemisphere Motor areas Prefrontal cortex Sensory areas and related association areas Central sulcus Primary somatosensory cortex Somatosensory association cortex Somatic sensation Taste Wernicke’s area (outlined by dashes) Primary visual cortex Visual association area Vision Auditory association area Primary auditory cortex Hearing Primary motor cortex Motor association cortex Primary sensory cortex Sensory association cortex Multimodal association cortex
Copyright © 2010 Pearson Education, Inc. Primary Motor Cortex Located in the precentral gyri Allows conscious control of precise, skilled, voluntary movements
Copyright © 2010 Pearson Education, Inc. Figure 12.9 Toes Swallowing Tongue Jaw Primary motor cortex (precentral gyrus) Motor Motor map in precentral gyrus Posterior Anterior Motor homunculi: upside-down caricatures representing the motor innervation of body regions
Copyright © 2010 Pearson Education, Inc. Premotor Cortex Anterior to the precentral gyrus Controls learned, repetitious, or patterned motor skills
Copyright © 2010 Pearson Education, Inc. Broca’s Area Present in one hemisphere (usually the left) A motor speech area that directs muscles of the tongue
Copyright © 2010 Pearson Education, Inc. Frontal Eye Field Controls voluntary eye movements
Copyright © 2010 Pearson Education, Inc. Sensory Areas Primary somatosensory cortex Somatosensory association cortex Visual areas Auditory areas Olfactory cortex Gustatory cortex Visceral sensory area Vestibular cortex
Copyright © 2010 Pearson Education, Inc. Figure 12.8a Gustatory cortex (in insula) Primary motor cortex Premotor cortex Frontal eye field Working memory for spatial tasks Executive area for task management Working memory for object-recall tasks Broca’s area (outlined by dashes) Solving complex, multitask problems (a) Lateral view, left cerebral hemisphere Motor areas Prefrontal cortex Sensory areas and related association areas Central sulcus Primary somatosensory cortex Somatosensory association cortex Somatic sensation Taste Wernicke’s area (outlined by dashes) Primary visual cortex Visual association area Vision Auditory association area Primary auditory cortex Hearing Primary motor cortex Motor association cortex Primary sensory cortex Sensory association cortex Multimodal association cortex
Copyright © 2010 Pearson Education, Inc. Primary Somatosensory Cortex In the postcentral gyri Receives sensory information from the skin, skeletal muscles, and joints Capable of spatial discrimination: identification of body region being stimulated
Copyright © 2010 Pearson Education, Inc. Figure 12.9 Genitals Intra- abdominal Primary somato- sensory cortex (postcentral gyrus) Sensory Sensory map in postcentral gyrus Posterior Anterior
Copyright © 2010 Pearson Education, Inc. Somatosensory Association Cortex Posterior to the primary somatosensory cortex Integrates sensory input from primary somatosensory cortex Determines size, texture, and relationship of parts of objects being felt
Copyright © 2010 Pearson Education, Inc. Visual Areas Primary visual (striate) cortex Extreme posterior tip of the occipital lobe Receives visual information from the retinas
Copyright © 2010 Pearson Education, Inc. Visual Areas Visual association area Surrounds the primary visual cortex Uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
Copyright © 2010 Pearson Education, Inc. Auditory Areas Primary auditory cortex Superior margin of the temporal lobes Interprets information from inner ear as pitch, loudness, and location Auditory association area Stores memories of sounds and permits perception of sounds
Copyright © 2010 Pearson Education, Inc. OIfactory Cortex Medial aspect of temporal lobes is also part of the limbic system) Region of conscious awareness of odors
Copyright © 2010 Pearson Education, Inc. Gustatory Cortex In the insula Involved in the perception of taste
Copyright © 2010 Pearson Education, Inc. Visceral Sensory Area Posterior to gustatory cortex Conscious perception of visceral sensations, e.g., upset stomach or full bladder
Copyright © 2010 Pearson Education, Inc. Vestibular Cortex Posterior part of the insula Responsible for conscious awareness of balance (position of the head in space)
Copyright © 2010 Pearson Education, Inc. Multimodal Association Areas Receive inputs from multiple sensory areas Send outputs to multiple areas, including the premotor cortex Allow us to give meaning to information received, store it as memory, compare it to previous experience, and decide on action to take
Copyright © 2010 Pearson Education, Inc. Multimodal Association Areas Anterior association area (prefrontal cortex) Contains working memory needed for judgment, reasoning, persistence, and conscience
Copyright © 2010 Pearson Education, Inc. Limbic Association Area Part of the limbic system Provides emotional impact that helps establish memories