An Introduction to Brain and Behavior PDF

An Introduction to Brain and Behavior CHAPTER 2 What is the nervous system’s functional anatomy? This chapter describes the basic structure and function of the brain Although the brain has structure, the brain is not a static organ; we are not born with a brain that remains unchanged for the rest...

An Introduction to Brain and Behavior CHAPTER 2 What is the nervous system’s functional anatomy? This chapter describes the basic structure and function of the brain Although the brain has structure, the brain is not a static organ; we are not born with a brain that remains unchanged for the rest of our lives. The brain is a plastic organ; neural tissue has the ability to adapt to the world  neural plasticity Example: learning Navigating the brain – different orientation systems Brain-Body Orientation  illustrates brain structure location from the frame of reference of the human face From Latin: “aimed towards or located” Dorsal: dorsum  back Ventral: venter  belly Medial: mediālis  middle Lateral: laterālis  side Anterior: anterior  before / in front of Posterior: posterior  after / behind Navigating the brain – different orientation systems Spatial Orientation  illustrates brain structure location in relation to other body parts and body orientation Rostral: rostrum  beak Superior: superior  above Caudal: caudum  tail Inferior: inferior  below Navigating the brain – different orientation systems Anatomic Orientation  illustrates the direction of a cut or section through the human brain from the perspective of a viewer  Navigating the brain – formative assessment 1. FORMATIVE ASSESSMENT 5. NAVIGATING THE BRAIN 4. 3. NB: memorize pp. 38-39! 6.  Try to translate some of the Latin expressions for a better understanding  Try to figure out the plane of section and view for each figure in the book 2. Brain protection – meninges & cerebrospinal fluid (CSF) Meninges Dura mater Frontal view Arachnoid + Pia mater a.k.a leptomeninges from λεπτός (Greek) leptos = thin Blood supply of the brain Cerebrovascular accident (CVA, ‘stroke’) Ischemic CVA (80%) Hemorrhagic CVA (20%) Blockage of blood vessel by clot Burst of vessel bleeding into the brain NB: behavioral consequences of stroke are extensively covered in subsequent course ‘Brain Dysfunction’ The brain from the outside Main structures visible from the outside: 1. Cerebrum 2. Cerebellum (‘little cerebrum’) 3. Brainstem NB: the higher a structure is located physically, the ‘higher’ its function. (higher in the sense of more complex, more integrated) The Cerebral Cortex – the brain’s outer “bark” layer Total surface area ~0.25 m2 ~40 x 62.5 cm ~ 2- 4 mm 4x = Gyrus ≈ curve, bend (γύρος) e.g. superior temporal gyrus Frontal view (coronal section) Sulcus = groove (Latin) e.g. central sulcus Lateral view Fissure = deep sulcus e.g. lateral fissure, longitudinal fissure Inside the brain Gray matter: nerve cells (no insulating layer) White matter: nerve fibers (insulating layer, fatty myelin) video (5 min) Frontal view (coronal section) corpus callosum Ventricle System 4 interconnected cavities filled with cerebrospinal fluid (CSF)  view 3D model online 1st and 2nd = lateral ventricles  one in each hemisphere Third ventricle  diencephalon; between right and left thalamus Fourth ventricle  between the cerebellum and the pons Presumed function = maintaining brain metabolism, excretion of metabolic waste, cushion the brain Recap Part 1 – Brain anatomy and physiology  meninges  arteries & stroke  cerebrum, cerebellum, brainstem  gyri, sulci and fissures  gray matter, white matter  ventricle system Video summary (15 minutes) Additional content:  The meninges: video (15 minutes)  Dissection of the ventricular system: video (27 minutes) Part 2 – Brain anatomy and physiology  Organization of the human nervous system  Cells and Fibers – Gray and White matter  Spinal cord, Brainstem, Forebrain The human nervous system – organization NB: Skip Enteric Nervous System (ENS) pp. 64-66 The human nervous system – organization Ontogenetic organization (evolution of brain development) NB: knowledge of the classifications and structures is required for the exam! memorize figure 2-14 p48 Greek: έν = in κεφαλή = head  encephalon = “in the head” The human nervous system – organization In Brain and Behavior, we discuss brain anatomy from the bottom up: 1. Spinal cord 2. Brainstem 3. Forebrain NB: the higher a structure is located physically, the ‘higher’ its function. (higher in the sense of more complex, more integrated) Cells and Fibers – wiring up the brain Brain tissue consists of 2 types of nerve cells Cells are connected through nerve fibers (axons)  neurons, major brain functions A bundle of nerve fibers is called:  glia, support cells (lit. glue)  tract (within the CNS)  nerve (outside of the CNS) (See also Chapter 3) corpus callosum  The spinal cord (part of CNS) Meninges inside = gray matter  nerve cells outside = white matter  nerve fibers (tracts) cf. brain tissue: inside = white matter outside = gray matter Spinal nerves - segments and dermatomes Five spinal cord segments: 1. Cervical 2. Thoracic 3. Lumbar 4. Sacral 5. Coccygeal Each dermatome (body segment) has two spinal (peripheral) nerves: a sensory nerve (afferent) to send information from the skin, joints, and muscles to the spinal cord a motor nerve (efferent) to control the muscle movements in that particular body segment. Directional flow of neural information Afferent: toward a structure (“input”) Sensory pathways are afferent (incoming) Efferent: away from a structure (“output”) Motor pathways are efferent (outgoing) Mnemonics: First input, then output First afferent, then efferent First a then e (alphabetically) a = arriving = afferent e = exit = efferent Spinal nerves – Law of Bell and Magendie dorsal / posterior root  sensory (afferent)  pain, temperature, touch ventral / anterior root  motor (efferent)  muscle movement, reflexes NB: spinal nerves are located on the left and right side of the spinal cord (bilateral pairs) Only the right side of the spinal cord is clearly illustrated in Figure 2.31 p.62  Cranial nerves no Name Functions 1 Olfactory Smell 2 Optic Vision 3 Oculomotor Eye movement 4 Trochlear Eye movement 5 Trigeminal Masticatory movements and facial sensation 6 Abducens Eye movement 7 Facial Facial movement and sensation 8 Auditory vestibular Hearing and balance 9 Glossopharyngeal Tongue and pharynx movement and sensation 10 Vagus Heart, blood vessels, viscera, movement of larynx and pharynx 11 Spinal accessory Neck muscles 12 Hypoglossal Tongue muscles 12 pairs of cranial nerves  one set controls the left side; the other set controls the right side of the head NB you do not need to memorize the cranial nerve numbers, just learn their names and main functions Cranial nerves - Bell’s Palsy  Inflammation of the facial nerve (7th cranial nerve)  swelling  compression  (partial) loss of nerve function  Symptoms  unilateral weakness or paralysis of facial muscles  Primary cause = viral infection  Treatment  anti-inflammatory drugs and antiviral agents  Most patients fully recover (temporary loss of function) NB: symptoms are also common in stroke, tumor and trauma Autonomic nervous system (ANS) Sympathetic division  stimulation: activation, arousal (fight or flight)  connected to thoracic and lumbar spinal cord segments  ganglia (‘minibrains’) near spinal cord  preganglionic fibers short, postganglionic fibers long  acetylcholine (preganglionic) + norepinephrine (postganglionic) Parasympathetic division  inhibition: relaxation, digestion (rest and digest)  connected to sacral spinal cord segments, but mostly to three cranial nerves (vagus, facial, and oculomotor) acetylcholine?  ganglia (‘minibrains’) near target organs norepinephrine?  preganglionic fibers long, postganglionic fibers short see chapter 5:  acetylcholine (preganglionic + postganglionic) neurotransmitters The brainstem Hindbrain = rhombencephalon (metencephalon+ myelencephalon)  mainly motor functions Midbrain = mesencephalon  sensory functions Between brain = diencephalon  integrative sensorimotor tasks  Hindbrain (rhombencephalon) relative cerebellum size metencephalon (across brain)  pons + cerebellum myelencephalon (spinal brain) large small  medulla Reticular formation  net-shaped mixture of neurons (gray matter) and nerve fibers (white matter)  arousal, sleep/wake (see Chapter 13) Pons (‘bridge’)  connects cerebellum with rest of the brain Medulla (‘marrow’) & Pons  control many vital body functions (e.g. breathing and cardiovascular system) Cerebellum (‘little cerebrum’)  controls complex, finely coordinated movements (e.g. running, dancing, playing darts) (see Chapter 11)  Midbrain (mesencephalon) Substantia nigra Healthy Parkinson Ventral (motor) Dorsal (sensory) Between brain (diencephalon) dia (διά) = between Thalamus (θάλαμος) = chamber  integrates sensory input and relays it to appropriate areas of cerebral cortex (see chapter 9, 10) Hypothalamus = below the thalamus  controls hormone production via pituitary gland (see chapter 12)  takes part in nearly all aspects of behavior (e.g. feeding, sleeping, temperature regulation, sexual and emotional behavior, hormone function, movement) Forebrain – Basal ganglia Ganglion (γαγγλίον) = cluster of neurons control and coordinate voluntary movement act as “volume control” by controlling the force of movements (see also Ch.11) Hypoactivity  Parkinson (Dopamine -) Hyperactivity  Tourette (Dopamine +) NB: substantia nigra and subthalamic nucleus are also part of the basal ganglia, but this is not mentioned in the book! View 3D model online ~ 2- 4 mm Forebrain – Cerebral cortex (outer layer of cerebrum) Total surface area ~0.25 m2 ~40 x 62.5 cm ~ 2- 4 mm 4x = Ten principles of nervous system function Ten principles of nervous system function 1. The nervous system produces movement in a perceptual world the brain constructs 2. Neuroplasticity is the hallmark of nervous system functioning 3. Many brain circuits are crossed 4. The CNS functions on multiple levels 5. The brain is symmetrical and asymmetrical 6. Brain systems are organized hierarchically and in parallel 7. Sensory and motor divisions permeate the nervous system 8. The brain divides sensory input for object recognition and motor control 9. Brain functions are localized and distributed 10. The nervous system works by juxtaposing excitation and inhibition NB: These principles are very general. Do not take them too literally, just use them as a steppingstone