Chapter 3 Structure and Function of the Nervous System Microscopic Level Basic structure function of a single neuron and its interaction with another neuron Macroscopic Level How billions of neurons are grouped into functional components that make up the nervous system Categorizing PNS cranial and spinal nerves as well as functionality Bundle of axons Group of cell bodies PNS Nerve Ganglion CNS Tract Nucleus Terms of Anatomical Direction in the NS Neuraxis An imaginary line drawn through the center of the CNS from the bottom of the spinal cord to the front of the forebrain Bent in humans because evolution changed from quadrupedal to bipedal Dorsal back Ventral belly Anterior Top towards head Posterior Bottom towards feet Lateral Going outwards Medial Going inwards middle The Brain 2D images of brain from different cuts Horizontal see anterior and posterior lateral and medial missing dorsal and ventral dimension Sagittal typical brain image mid sagittal section of brain see anterior and posterior dorsal and ventral missing lateral and medial dimension Coronal see dorsal and ventral lateral and medial missing anterior and posterior dimension Starts out as neural tube hollow inside filled with cerebrospinal fluid forebrain midbrain hindbrain and spinal cord 3 weeks Differentiation occurs because things begin growing at different rates Forebrain Cerebral Hemispheres outer surface is the Cortex wrinkled with ridges and grooves Ridge gyrus Groove sulcus surround define gyrus prominent grooves are called fissures Cortex mainly made of unmyelinated cell bodies Gray matter appears grayish in color Pituitary In center of gyruses are myelinated axon pathways white matter Lobes Lateral Fissure Sylvian Fissure Frontal Lobe Precentral Gyrus primary motor cortex immediately anterior to central sulcus skeletal muscles and controls voluntary movement one hemisphere controls the opposite side of the body Topographical organization of body muscles map of body muscles and muscle groups nearby locations correspond to nearby muscle groups Look up motor homunculus picture for better detail Broca s Area controls speech articulation and grammatical structure Lateralized to the left hemisphere Lesion causes Broca s Aphasia impaired word production unimpaired word comprehension Prefrontal Cortex planning decision making impulse control Postcentral Gyrus Primary Somatosensory Cortex processes skin senses body position Parietal Lobe Association Cortex further sensory info processing One hemisphere serves the opposite side of the body Topographical organization look up somatosensory homunculus for better detail Found this with neurosurgeon s experimentation using exposed brains and electrodes then ask if they feel anything no pain receptors in the brain so they don t feel the cutting More receptors for hand sensations so a larger brain region controls it than for example the hip Not involved in a primary function but receive info form primary cortexes and process use that information high order cognitive functions integrates info from other senses Location of objects in space Plasticity can change in response to experience especially when their jobs use a lot of maps directions like a taxi driver in London tends to change dramatically when people use his her spatial abilities Unilateral Neglect ignoring objects stimulation on the side opposite to the damage more common on the right parietal lobe visual auditory tactile anything on the left side of the body usually temporary Occipital Lobe Contains the visual cortex processes visual information Primary Visual Cortex V1 bright green First neurons to respond to stimulation visual input from the retina Extract and detect edges very basic Process simple features ex orientation Topographical organization of visual space map of the two retinas Seven cortexes V2 V7 which do higher processing as you move from this spot process all this before you even realize what you re seeing because it has to be processed first before being sent to other lobes for you to use Temporal Lobe Auditory Cortex bright blue Receives auditory hearing info from the ears Wernicke s Area red Language comprehension Lateralized to the left hemisphere Lesion causes Wernicke s Aphasia Impaired word comprehension Unimpaired word production Word salad Inferior Temporal Cortex Visual identification of familiar objects like faces Lesion causes trouble identifying things man who mistook his wife for a hat literally couldn t tell Corpus callosum callous looking thing body Large band of myelinated axons connect homologous regions of separate hemispheres carries info between two hemispheres Typical of mammals In females it is slightly larger meaning the female brain is better integrated Other Brain Structures Ventricles cavities in the brain that contain cerebrospinal fluid Carries materials from blood vessels to CNS Transports waste away Forebrain 2 lateral ventricles and third ventricle Midbrain cerebral aqueduct Hindbrain fourth ventricle Thalamus acts as a sensory relay station relays incoming sensory information to the cortex Nucleus cluster of gray matter in the brain Thalamus is a giant cluster of nuclei Hypothalamus Different regions are specific for different senses but they are connected and talk chemical senses excluded e g smell Coordinates emotional and motivational functions sex eating emotion and aggression Also controls the pituitary gland which controls the rest of the endocrine gland system hormones Midbrain Tectum dorsal side of midbrain Roof of the midbrain Superior colliculus vision e g eye movement Reflexive like eye coordination Inferior colliculus hearing Tegmentum ventral side of the midbrain Hindbrain Pons bridge Control of movement Substantia Nigra dopamine producing neurons Parkinson s disease El dopa adding dopamine but have to make sure they don t get used to the level Ventral Tegmental Area plays a role in the rewarding effects of food sex drugs and Rock Roll Cerebellum little brain Sensory neurons pass through on the way to thalamus motor neurons pass through between cortex and cerebellum Outside is mostly white matter inside is gray matter It is part of the reticular formation loose tract of brain cells sleep and arousal Very complex structure many neurons Motor coordination and balance motor learning cognitive functions even language attention memory Involved in just about everything we do hard to figure out exactly what it s doing If lesion happens on cerebellum