5 Major Divisions Brain Spinal Cord Processes information coming in from afferent nervesSends signals (motor) out to body via spinal cord and cranial nervesSpinal CordConnects brain to peripheral nervesMay also initiate motor responses (reflexes)
6 Brain Divisions - Anatomical Cerebrum (Cerebral Hemispheres)DiencephalonBrain Stem (Pons, midbrain, medulla)CerebellumEach of these divisions can be divided further, into anatomical AND functional divisions
7 Brain Ventricles“Spaces” in the brain that are left over from embryonic brain developmentSpaces are filled with cerebro-spinal fluidWhy?
8 Hydrocephaly “Water on the brain” Pressure inside the brain inceases due to too much cerebro-spinal fluid (CSF) being produced or drainage is blocked
15 Brain and Skull Frontal lobes lie within the anterior cranial fossa The anterior parts of the temporal lobes lie within the middle cranial fossaThe posterior cranial fossa houses the brain stem and cerebellum
16 Cerebral Cortex Only 2-4 mm thick, but 40% of brain mass Contains BILLIONS of neurons (convolutions increase surface area)Functional areas can be identified, but all areas of the cortex are interconnectedEach hemisphere is associated with the opposite side of the body (laterally)
17 StrokePeople that have motor areas affected on only one side of their brainOpposite part of the body may be paralyzed
19 Functional Cortex Areas Motor – initiates movement in areas of the bodySensory – Sensations from the body come here to be processedAssociation Areas – where incoming information from the body is processed
21 Primary Motor Cortex Located in the pre-central gyrus Pyramidal cells – allow conscious control and coordination of voluntary movementsConnect to spinal cord (pyramidal tracts)Motor areas are not simply discrete, but interconnected!
22 Premotor Cortex Anterior to precentral gyrus Provides a ‘memory bank’ for skilled motor activitiesAlso controls motor activity that rely on sensory feedback
24 Broca’s Areas Control the muscles that are responsible for speech Also active during “planning” of motor activitiesWould you expect this area to be smaller or larger in chimps (our closest animal relative)?
28 Sensory Areas – Primary Somatosensory cortex Post-central gyrus of the parietal lobeNeural input from the skin and proprioreceptors (from muscles and joints) is decoded and the stimulated body part is identified (spatial discrimination)
29 Somatosensory Association Cortex Integrates sensory inputs to produce an understanding of what is being feltDEMOWhat would damage to this area do?
30 Label the Primary and Association Somatosensory Cortices
31 Primary Visual CortexReceives input from the cells in the retina of the eye
32 Visual Association Cortex Uses past visual stimuli “visual memories” to determine what is being seenUses different aspects of the visual data (shape, contrast, depth perception, etc.)
33 Primary Auditory Cortex Superior margin of temporal lobeGathers data on pitch, loudness and location (by the difference in impulses received by each ear)Auditory Association Area – interprets sound by relating to past auditory memories
34 Olfactory Cortex On medial aspect of temporal lobe Part of the old “rhinencephalon” (nose brain) that still existsMost of the rest of our ancestral rhinencephalon has evolved to process “higher” emotions – the limbic system
36 InsulaPart of the cerebral cortex that is just deep to the temporal and frontal lobesSeen when temporal lobe is retracted
37 Other Cortices Gustatory Cortex - Perceives taste stimuli Just deep to temporal lobe (on the insula)Visceral Cortex – Perceives information from the gutJust posterior to gustatory cortexVestibular Cortex – provides information about the position of the head in spacePosterior of insula
38 Multimodal Association Areas Generally receives information after being processed by the association cortices for each senseReceives input from multiple stimuli, andGive meaning to itDevote it to memoryAct upon itRelate it to previous experienceSenses related to conciousness
41 Anterior Association Area In frontal lobeCenter forIntellectPersonalityJudgementPlanningAbstract Ideas
42 Posterior Association Area Temporal, parietal, occipital lobesAllows to recognize:Patterns and facesLocalizing yourself in spaceSelf-awareness
43 Limbic Association Area Includes the singulate gyrus, hippocampusProvides emotional impact that is tied to certain situationsExample?
44 Lateralization Each hemisphere of the brain is functionally identical However, each hemisphere is considered to be functionally different (slightly) in higher brain functions, but research continues“Left-brain” – math, logic, language“Right-brain”- art, music, creativity
45 Cerebral White Matter Deep to the cortex Connects “grey matter” cortices to each other and to the lower CNS (spinal cord)White color is due to the myelination of the fibers composing the tissue
47 White Matter FibersCommissures – Connect corresponding grey matter of the two brain hemispheresAllows them to act togetherAssociation Fibers – Connect different parts of the same hemisphereProjection Fibers – connect the brain to the rest of the nervous system (spinal cord)
48 DiencephalonForms the core of the forebrain (surrounded by cerebral hemispheres)3 major divisionsThalamusHypothalamusEpithalamus
49 Thalamus Consists of 2 bilateral egg-shaped “nuclei” Serves as a relay station for all impulses entering the brainAll afferent impulses are directed to the relevant areas of the brainAll efferent impulses are directed to the relevant areas of the body
50 Hypothalamus Located inferior to the thalamus The main visceral control center of the body, maintains homeostasis
52 Hypothalamus Functions (con’d) Food intakeMonitors glucose levels in the bloodWater balance and thirstMonitors levels of solute concentrations in the bloodSleep-wake cyclesMajor controller of the endocrine system
53 Epithalamus Most dorsal portion of the diencephalon Most notably contains the pineal gland, which secretes the hormone melatoninHelps regulate the sleep-wake cycle
54 Brain Stem Directly inferior to diencephalon Three major areas MidbrainPonsMedulla Oblongata
56 Pons Helps to maintain the normal rhythm of breathing Serves as a bridge between the motor cortex and the cerebellum
57 Medulla OblongataLocated just in the opening of the foramen magnum (top of spinal cord)Regulates many homeostatic functionsCardiovascular regulationRespiratory rhythmHiccuping, coughing, vomiting, swallowing, sneezing
58 CerebellumBilaterally symmetrical organ that occurs inferiorly to the occipital lobeTimes our efferent motor impulses, resulting in smooth coordinated movements
59 Cerebellar Processing Cerebral motor areas relay their intent to start voluntary muscle contractionAfferent impulses from proprioreceptors send information about body position and momentumCerebellar cortex calculates the amount and direction of muscle contraction needed to complete the actionThe “plan” of motion is sent back to the motor areas of the cerebrum, where impulses are sent for the action to be executed
60 The Limbic System Our “emotional” brain Composed of organs that surround the upper brain stemRhinencephalonCingulate gyrusAmygdalaHypothalamusFornix
62 Emotional Brain Amygdala Cingulate gyrus Recognizes fearful facial expressionsCore of the fear responseCingulate gyrusHelps to express emotions as gesturesResolves mental conflicts
63 Crossed Communication Even NumbersThe limbic system communicates directly with the frontal lobe via white matter.Odd NumbersMost limbic system actions are regulates by the hypothalamusWhat issues might these connections cause??
64 The Reticular Activating System The reticular neural formation extends from the brain stem into many major areas of the brainMakes this system ideal for arousing the brain as a wholeThe RAS filters out “typical” stimuli, but arouses the brain when something unusual or significant happens
65 Levels of Consciousness AlertDrowsy/LethargicStuporComaWhat causes us to shift along this continuum?
66 Memory The storage and retrieval of information Memories are stored in parts of the brain that need them (e.g. visual association cortex for memories of shapes)What affects the vividness and length of memories?Emotional StateRepetitionAssociation (mnemonic devices)
67 Protection of the Brain Meninges (Physical protection)Cerebrospinal Fluid (Physical Protection)Blood-Brain Barrier (Chemical Protection and Immune Function)
68 Meninges Sheets of fibrous connective tissue that surrounds the brain Dura MaterContinues inferiorly as the spinal dura materArachnoid membranePia mater
70 Cerebrospinal FluidFills the spaces in and around the brain and spinal cordVentriclesMeningesAbsorbs shock, provides buoyancy and delivers materials (electrolytes, etc.) to the brain
71 Spinal Tap CSF may need to be sampled to check for infection/injury No blood/bacteria should be isolated from CSF in healthy individuals
72 Blood-Brain Barrier Brain needs to be protected from PathogensWild swings in chemistryCapillaries serving the brain are only permeable to the smallest molecules essential for brain functionTight junctions in blood vessel epitheliaAstrocytes – limit what comes in and out of brain tissueAlways a good thing?
73 ConcussionGenerally due to a violent jarring or twisting of the brain inside the cranium
74 Progressive Brain Diseases What types of diseases are responsible for slow, progressive loss of mental function?Name of diseaseSymptomsMode of pathologyPrognosisTreatment
75 Spinal Cord - Anatomy Enclosed by the neural arches of the vertebrae Extends from the base of the skull to the 1st-2nd lumbar vertebrae
76 Spinal Cord - FunctionProvides afferent and efferent nerve pathways to and from the brain and peripheral nervesMajor reflex center
77 Spinal Cord – Protection Resides within the spinal canal (vertebrae)Also surrounded by meningesSpinal Dura MaterArachnoid MembranePia MaterCSF between arachnoid membrane and pia mater
79 EpiduralsAnesthetic is placed in epidural space using a fine needle (catheter)Often used during labor, surgery or diagnostic procedures
80 Spinal Cord TerminusSpinal cord ends at the conus medullaris at 1st-2nd Lumbar vertebraFilum terminale anchors the spinal cord to the coccyxNerve roots for lumbar and sacral region extend through the vertebral canal and exit through their respective vertebrae