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Brain Behavior Slides Lec 3

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  • Talk Overview of functional neuroanatomy (scaffolding) Discuss general principles of cortical functioning Discuss brain-behavior relationships---(relying on research from patients with brain damage—strokes, localized lesions, functional imaging, and etc.) Review of cells of nervous system and how communicate (wiring) Allude to link between limbic and frontal in all or most psychiatric disorders The nervous system may be considered as a set of functional units classified as sensory, motor, and association. » Internal Representation of the external world » » Manipulate the environment and to influence others’ behavior through communication » Drive the actions of motor systems’ information processing is essential for sorting logical thought from the distortions introduced by psychopathology.
  • HINDBRAIN Brain stem-upward extension of spinal cord: in general brain stem regulates many movements that animals make—respond to sensory features, regulates eating, drinking, body temp, sleep, waking, sexual behavior) Medulla (afferent and efferent tracts run through it; nuclei involved in movements of mouth and throat necessary for swallowing, speech, gagging, drooling)—basic life maintaining centers (respiration, blood pressure, heart beat) Reticular Formation: (complex network of cells and fiber tracts that extends towards the nose….from medulla and projects to thalamus which projects to all cortex—important in arousal)—brain stem lesions involving RAS give rise to sleep disturbances and global disorders of consciousness Cerebellum: concerned mainly with motor coordination, muscle tone, balance (although evidence for role in higher cognition)—housed in the posterior fossa » Damage: impairs standing, walking, coordinated movement—jerky poorly coordinated movement or exaggerated movements FOREBRAIN Diencephalon thalamus (consists of several nuclei—all sensory systems except oflaction relay in thalamus on way to the cortex)—eg. lateral geniculate (visual); medial genigulate (auditory) hypothalamus (many nuclei-master control for autonomic nervous system which regulates glands smooth muscle, cardiac muscle—fight or flight; organizes behavior related to 4F’s feeding, fighting, fleeing, mating--;regulates endocrine functioning) » Hypothalamic dysfunction: disturbances in food intake, water balance, sexual functions, temp; high fever
  • Deep within (subcortical) nuclei—Basal Ganglia and Limbic System Number of Nuclear Masses known as basal ganglia 3 Functions: 1. Damage to different portions produce changes in posture, increase or decrease in muscle tone, abnormal movement such as twitches, jerks, tremors—role in motor functions (Parkinson’s/Huntington’s) 2. Sequence movements into smoothly executed response 3. Support habit learning—procedural memory-- Limbic System: (medial to temporal lobes--motivation, emotion, memory) hippocampus, amygdala, mammillary bodies, cingulate Cerebral Hemispheres: main focus 6 cell layers (varies based on input or output) 5 &6 (bottom): send axons to other brain areas—well developed layers in motor areas 4: receives axons from other areas (well developed in sensory areas) 1-3: receives input from 4 th ; well developed in association areas development of cytoarchitecture maps—Broadman) Highly convoluted layer of nerve cells-Cerebral cortex or grey matter (hills gyri and valleys sulci) Deep sulci are fissures: longitudinal (hemispheres); central (or rolandic-frontal from parietal): lateral (or sylvian-temporal from frontal and parietal)
  • Axons that connect=white matter Cortical Connections: various regions of neocortex and interconnected by 3 types of axons projections **Important bc Damage to a pathway is often reflected in behavioral deficits as severe as those suffered following damage to functional area they connect—eg. may see deficit not bc of frontal lesion but because of damage to axons projecting to that area Some disorders result from anatomic disconnection between 2 cortical areas Apraxia (inability to work or perform purposeful action)---different types—one type ideomotor apraxia: unable to perform skilled movements to verbal command but can perform spontaneously—damage to arcuate fasciculus—fiber connection between language comprehension in posterior left temporal and motor association in left frontal OR Damage to anterior corpus callosum: disconnection between verbal comprehension in left and motor strip in right such that may not be able to comb hair with left hand but can comb with right
  • Overview: [CNS-brain (neurons/glial) and spinal cord—encased in bone, floating in cerebralspinal fluid) Blood Supply: brain cannot store fuel or extract energy w/o oxygen—need constant blood supply—1 sec interruption uses up much O2 and 6 sec produces unconsciousness—permanent damage in a few minutes What are the main arteries that serve the brain? 1. Anterior circulation (common carotid—internal/external carotid—ICA into middle and anterior cerebral arteries) 2.Posterior circulation (supplied by vertebral-basilar system –vertebral arteries fuse at pons and become basilar artery—extends to midbrain and bifurcates forming left and right posterior cerebral arteries MCA: largest of cerebral arteries—supplies most lateral surface of the brain, branches supply portion of basal ganglia and posterior limb of internal capsule (bundles of fiber tracts containing descending motor and ascending sensory fibers) ACA: medial surface of brain from anterior frontal to parietal-occipital fissure; branches feed anterior limb of internal capsule, putamen, head of caudate PCA: medial and ventral surface of temporal lobe, including hippocampus, visual cortex—some of thalamic nuclei Tell me the order of the meninges BRAIN-Pia mater—CSF-Arachnoid Membrane (soft, spongy) —Dura mater (hard mother) More about CSF: brain floats in DSF contained within the subarachond space—protect from shock, reduce weight—brain contains hollow, interconnected chambers called ventricles filled with CSF—lateral/3 rd ventricle/cerebral aqueduct/fourth ventricle—produced and circulates Blockage of CSF: hydrocephalus
  • Cortical Zones: Primary, Secondary, Tertiary Primary: primary projection area, incoming sensory information projected to sense-modality specific neurons; each sense is contralateral except olfaction)---eg. touch right index—projects to left parietal Primary Visual Cortex (receives visual information—upper and lower banks of calcerine fissure) Primary Auditory Cortex (receives auditory information—upper surface of lateral fissure Primary Somatosensory Cortex (receives information from body senses) Primary Motor: neurons here connected to different connections Show homogulous Secondary zones (association cortex): receive modality specific information from primary cortex—damage results in inability to perceive or comprehend what one is touching or seeing (depending on where damage is)—other senses can compensate. Tertiary Zones; Integration of information across sense modalities occurs (writing to dictation may be impaired) Will discuss 2. Cortical Lobes (one way to organize—but remember multiple 3. Functional systems: many different areas work together for certain function (e.g, reading) Cortical activity at every level is maintained and modulated by complex feedback loops—some within the cortex others involving subcortical areas) (e.g, parallel) Lateralizatio of function: left hemisphere (verbal/sequential) Right: nonverbal/visuospatial (Describe Sperry or WADA)
  • Show slide (Lezak, p. 57) Left hemisphere of most rt handed persons is larger and heavier than right; esp in areas that mediate language Areas involved in visuospatial transformation larger on right than corresponding left May also be differences at the cell layer—more organized of left and more diffuse on right—Clinically this means that patients with right hemisphere damage have a reduced capacity for tactile discrimination and sensorimotor tasks in both hands while those with left-hemisphere damage experience impaired tactile discrimination ONLY in contralateral hand---may depend on function (left hemisphere damage—bilateral deficits; right hem damage—ONLY contralateral) Left Right Linear Processing (verbal statements, rapid motor seq) Config processs (face, 3-D spatial relationships) Reading, writing, understanding, speaking, verbal memory reception & storage visual data, copying and drawing Numerical symbols, seq of hand, arm, speech recog non-verbal sounds, aspects of musical ability Less adept at perception shapes, textures, patterns, imagery, copying Split Brain Studies Right hemisphere stroke patients may be better at detecting lies Right hemisphere damage: Quiet fluent, verbose, illogical and loose generalizations, difficulty organization (incl music), literal interpretations, loss of gist, left sided inattention, difficulty copying designs, Diminished contribution from one hemisphere may be accompanied by exaggerated activity of other when released from inhibitory or competitive constraints of other hemisphere. Hemispheric differences in emotion and personality changes after brain injury. Left damage: Catastrophic reaction (extreme and disruptive transient emotional disturbance) Anxiety Oversensitive to disabilities/cautious Right damage Less likely to be aware of problems Risk-takers Indifference (left sided paralysis)/apathy Low mood Some suggestion that each hemisphere specialized for positive (left) and negative (right) May depend on anterior/posterior axis (right posterior depression and left posterior paranoid). This may not hold true for mild strokes.
  • Use strategies to improve at each stage
  • Primary injury: blunt trauma and rotational forces that occur at the moment of trauma (show examples) Secondary: injuries that arise following the injury: damage to the brain due to raised intracranial pressure, hypoxia, neural damage due to blood-neuron contact Factors involved in Trauma a.      Shearing: pulling apart of axons and disruption of cell bodies b.      Extensive Diffuse axonal injury: impairs cortical-cortical and cortical to subcortical pathways (mild acceleration/deceleration may have DAIS at cortical level but more severe DAI at deeper layers)—shear strain in brain stem (RAS) unconsciousness c.      Contusion (coup and countercoup)----REGARDLESS of impact maximum contusion occurs at anterior and ventral surfaces of frontal lobes and anterior poles and ventral surfaces of temporal lobe due to bony protuberances d.      Skull Fractures e.      Edema/Hemorrhaging f.        Hematoma (acute subdural is most lethal—mortality 60%--if survive more impaired than other TBI) g.      Neurochemical Effects: excessive release of ACH and perhaps other excitatory NT (gultamate) h.      Increased ICP : pressure or spasm of blood vessels can lead to ischemia Hydrocephalus ex vacuo : (vomiting, confusion, lethargy) Normal Pressure hydrocephalus (dementia, unsteady gait, urinary incontinency---slow accumulation ICP is within normal limits)
  • Variety of connections: Axon-Soma; Axon-dendrite, Neurotransmitters open voltage gated-channels

Brain Behavior Slides Lec 3 Brain Behavior Slides Lec 3 Presentation Transcript

  • Brain-Behavior Relationships
  • Gross Structures of the Brain
    • HINDBRAIN
        • Medulla
        • Reticular Formation
        • Pons and Cerebellum
      • MIDBRAIN
      • FOREBRAIN
        • Diencephalon (Thalamus, Hypothalamus)
        • Cerebrum (Basal Ganglia, Limbic System, Cerebral Cortex)
  • Cerebral Hemispheres
    • Basal Ganglia
      • 3 main functions
      • In current usage, the phrase 'basal ganglia' means: the caudate nucleus , putamen and globus pallidus .
    • Limbic System
      • 4 structures
    • Cerebral Cortex
  • Cortical Connections
    • Between hemispheres (e.g., corpus callosum)
    • Within a hemisphere, between one lobe and another (association tracks; e.g., arcuate fasciculus)
    • Cortex-Subcortical (e.g., internal capsule)
  • Review of Neuroanatomy (cont.)
    • Skull and Meninges
    • Vascular System
    • Ventricular System and CSF
  • Principles of Cortical Organization
    • Cortical Zones
    • Cortical Lobes
      • Occipital, Frontal, Parietal, Temporal
    • Functional Systems
    • Lateralization of Function
  • Cortical Lobes Vision Somato-sensory Auditory, Olfactory Visual Voluntary Motor; Speech Sensory/ Motor Occipital Parietal Temporal Frontal
  • Cortical Lobes
    • Occipital: Mediate sight; visual perception; visual knowledge
    • Parietal: tactile sensations; position sense; spatial relations
      • Left: sequential. Logical spatial
      • Right: holistic spatial information
  • Cortical Lobes (cont.)
    • Temporal: auditory and olfactory abilities; integrating visual perceptions with other sensory info; new learning; emotion; motivation
    • Frontal: motor functions, including speech; executive functions; integration of emotional and motivational states
  • Lateralization of Function
    • Left Hemisphere
    • Speech and Language
    • Linear Processing
    • Well-routinized codes
    • Details
    • Contralateral attention
    • Positive Emotions
    • Right Hemisphere
    • Prosody, Humor, Non-literal
    • Configural Processing (faces)
    • More adept at novel
    • Global Percepts
    • Global attention
    • Negative Emotions
  • Functions
    • Attention and arousal (see text)
    • Memory (know 4 different regions involved
      • Hippocampus + surrounding areas
      • Basal forebrain (cells that produce Acetylcholine)
      • Frontal Cortex
      • Basal Ganglia (procedural memory)
    • Language
  •  
  • Memory
    • Amnesia
      • Immediate vs. Long-term
      • Remote memory vs. Antereograde memory
      • Implicit vs. Explicit Memory
    • Frontal Lobes: role in retrieval and organization
      • The frontal lobes are the most advanced part of your brain. The frontal lobes are that part of your brain responsible for creativity, logic, intuition, new problem solving, synthesis of ideas, imagination, concepts of time, and planning.
  • Memory Rehabilitation Storage Encoding Attention Retrieval
  • Language
    • Aphasia
      • Expressive Aphasia
      • Receptive Aphasia
    • Distinguish
    • Psychological Issues
  • 5 Frontal-Subcortical Circuits
    • Motor
    • Occulomotor
    • Dorsolateral
    • Orbitofrontal-Ventral PFC
    • Anterior Cingulate
  • PREFRONTAL CORTEX SYSTEM The most evolved brain system Functions atention span perseverance planning judgmen impulse control organization self-monitoring and supervision problem solving critical thinking forward thinking learning from experience and mistakes ability to feel and express emotions influences the limbic system empathy internal supervision
  • Major Functional Divisions of Frontal Lobe
  • Dorsolateral Syndrome
    • “Executive function” deficits
    • Poor organizational strategies
    • Poor memory strategies
    • Working Memory
    • Impaired set-shifting
    • Attentional control (distractible)
  • Orbitofrontal-Ventral PFC Syndrome
    • Phineas Gage
    • Stimulus-Reward Associations
    • Decision-Making
    • Appropriate Social Behavior
  • Anterior Cingulate Syndrome
    • Akinetic Mutism
      • Apathetic, no spontaneous speak, answer in monosyllables
      • Display no emotion
  • Points to Remember
    • Behavioral deficits determined by site, size, laterality, nature of lesion, etc.
    • Individual variation.
    • Difficulty to develop real-world tasks to assess FL functioning.
  • Diseases that commonly affect Frontal functioning
    • Affective Disorders
      • Depression
    • Traumatic Brain Injury
    • Schizophrenia
    • Some Dementing Illnesses
  • Traumatic Disorders
    • Mechanisms of Injury
      • Primary
      • Secondary
    • Initial Assessment of Severity
      • Glascow Coma Scale
      • Length of Consciousness
      • Length of PTA
  • TBI (cont.)
    • Treatment
    • Cognitive and Emotional Effects
    • Rehabilitation
  • Principles of Nerve Cell Communication
    • Neuron Membrane
      • Electrostatic pressure
      • Diffusion
    • Communication within a neuron
      • Movement of electrical charge
    • Communication between neurons
      • Electrical signal to chemical signal
  • Biochemical Activity of the Brain
    • Membrane of Neuron
    • Synapse
    • 2 Types of Receptors
      • Ionotropic (fast but short-lived)
      • Metabotropic (slow, but prolonged effect)
    • Either may be excitatory or inhibitory
  • Neurotransmitters
    • Excitatory (glutamate)
    • Inhibitory (GABA)
    • Neuromodulators (dopamine)
  • Classes of Psychoactive Medications
    • Neuroleptics (Haldol)
    • Antidepresants (Prozac)
    • Tranquilizers (diazepam or Valium)
    • Stimulants (amphetamine)
    • Time Course and Side Effects