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Functional Organization of the Central Nervous System. Nervous System Central Nervous Peripheral Nervous System System Brain Spinal Cord. Central Nervous System is Organized in three ways 1. Hierarchical Organization
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Nervous System Central Nervous Peripheral Nervous System System Brain Spinal Cord
Central Nervous System is Organized in three ways 1. Hierarchical Organization 2. Lateralized Organization 3. Localized Organization
Hierarchical Organization Building a CNS from the bottom up to understand hierarchical control from the top down a: Spinal cord Do we have behavior with only a SC?
Reflexes monosynaptic reflex arc and pain b. Add Hindbrain and Cerebellum inactive decerebrate rigidity rudimentary location vital functions
c. Add Midbrain spontaneous locomotion sleep and wake cycles slight decrease in rigidity ¨seeing¨ and ¨hearing
d. Hypothalamus & Thalamus drives homeostatic mechanisms emotions (unchecked) hyperactivity
e. Basal Ganglia Slight decrease in hyperactivity Perseveration appears, inability to shift set
f. Limbic System normalization of activity & emotions ability to remember
g. Cerebral Cortex “normal functioning” individual differences
Lateralized Organization (more later) Right Side controls left & vice-versa Left Hemisphere Functions e.g., language, analytical reasoning Right Hemisphere Functions e.g., spatial skills, processing music Conservation of Nervous System Preservation of Language in Humans
Localized Organization Caution: this is not phrenology - Brain “centers” for behavior intricately connected with other brain areas involved in the same or related behavior - localization of sensation (primary & secondary areas), motor (primary & secondary), general areas of language (reading, talking, verbal reasoning), and spatial reasoning
Nomenclature Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon
Neuroanatomical Ogranization • Spinal Cord white matter vs gray matter myelination of axons dendrites, cell bodies and terminals are not myelinated dorsal horn & ventral horn
Brainstem medulla, pons & midbrain a. Medulla (Myelencephalon) center for vital functions decussation of the pyramids crossing over for most nerve fibers b. Pons (Metencephalon) numerous cranial nerves reticular formation raphe nucleus and sleep
c. Midbrain (Mesencephalon) Superior Colliculus Inferior Colliculus Central Gray (periaqueductal gray) Substantia Nigra Ventral Tegmentum Schizophrenia & Parkinson’s disease
3. Cerebellum (Metencephalon) smooth coordination of practiced movements integrates sensory & motor cognitive functions (with frontal lobe)
4. Hypothalamus (Diencephalon) 22 sets of nuclei homeostasis, biological rhythms drives • Thalamus (Diencephalon) Relay Station Topographic arrangement with cortex
Basal Ganglia (Telencephalon) Striatum (Caudate & Putamen) Globus Pallidus “Substantia Nigra”
Limbic System (Telencephalon) Hippocampus Amygdala Nucleus Accumbens “Prefrontal Cortex, Cingulate Cortex & Hypothalamus”
Cerebral Cortex (Telencephalon) - 6 layered structure - Four lobes: Frontal Parietal Temporal Occipital - sulcus (i) & fissure (s) (lateral, central) - gyrus (i)
Features of the Cerebral Cortex note: more on this later Somatosensory Cortex (homunculus) Motor Cortex (homunculus) Visual Cortex Auditory Cortex
Think about these questions while you prepare for the test: What is the significance of the homunculi as far as observable behavior is concerned? How do higher brain areas influence lower brain areas? What do localization, lateralization and hierarchical organization mean in reference to behavior?