Download ANPS 019 Beneyto-Santonja 10-24

ANPS 019 Beneyto-Santonja 10/24/12
Overview of the Central Nervous System  This lecture will introduce you to the terms we will
discuss throughout the rest of the semester.
Major CNS Regions and Functions
 Cerebrum
o Conscious thought processes, intellectual functions
o Memory storage and processing
o Conscious and subconscious regulation of skeletal muscle contractions
 Diencephalon
o Thalamus
 Relay and processing centers for sensory and motor information
o Hypothalamus
 Centers controls emotions, autonomic functions, and hormone
production
 Mesencephalon
o Processing of visual and auditory data
o Generation of reflexive somatic motor responses
o Maintenance of consciousness
 Pons
o Relays sensory information to cerebellum and thalamus
o Subconscious somatic and visceral motor centers
 Medulla Oblongata
o Relays sensory information to thalamus and to other portions of the brain stem
o Autonomic centers for regulation of visceral function (cardiovascular,
respiratory, and digestive system activities)
 Cerebellum
o Coordinates complex somatic motor patterns
o Adjusts output of other somatic motor centers in brain and spinal cord
How does the CNS get its adult shape?  Embryonic Development of the Nervous System
 Understanding the embryology helps to understand both anatomy and function of the
brain
 The nervous system begins forming around embryonic day 19 when the cell layer called
the ectoderm begins to fold
 Within a week, the neural plate closes to form the neural tube, which extends the length
of the embryo
 Cells of the Neural Tube become CNS cells
 Cells of the Neural Crest become PNS cells
Neural Crest: PNS Structures
 Sensory Ganglia (e.g., dorsal root ganglia)
 Autonomic (Sympathetic & Parasympathetic) Ganglia
 Schwann Cells
 Adrenal Medulla
 Digestive system neurons
Neural Tube closure begins in the middle of the embryo and proceeds in both directions
Neural tube defects can occur when the neural tube fails to close in development
 Spina Bifida  Failure of caudal neural tube closure
 Anencephaly  Failure of rostal neural tube closure
 Folic acid deficiency (70% of cases)
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High Glucose levels (diabetes mellitus)
Retinoic acid excess (vitamin A)
Neural tube events occur early in development, often before a woman realizes she is
pregnant
The Neural tube changes shape as it grows
 By week 4, 3 primary brain vesicles form
 By week 5, 5 primary brain vesicles form
Much of the CNS development occurs postnatally
Summary of Brain Development
1. Neural Tube; folding begins
2. Primary brain vesicles
a. Prosencephalon (forebrain)
b. Mesencephalon (midbrain)
c. Rhombencephalon (hindbrain)
3. Secondary brain vesicles
a. Telencephalon
b. Diencephalon
c. Mesencephalon
d. Metencephalon
e. Myelencephalon
4. Adult Brain structures
a. Cerebrum: Cerebral hemispheres (cortex, white matter, basal nuclei)
b. Diencephalon (thalamus, hypothalamus, epithalamus)
c. Brain stem: midbrain
d. Brain stem: pons
e. Cerebellum
f. Brain stem: medulla oblongata
g. Spinal cord
5. Adult neural canal regions
a. Lateral ventricles
b. Third ventricle
c. Cerebral aqueduct
d. Fourth ventricle
e. Central canal
Ventricles  The fluid-filled (CSF, cerebrospinal fluid) spaces within the brain resulting from
neural tube closure
 Delivers nutrients and removes wastes
How do we tell one part from another? What does each part of the brain do?
 Cerebrum
o Largest part of the brain
o Controls higher mental functions  Intellect, Reason, Learning and Memory,
Planning and Emotion
o Divided into left and right hemispheres by the Longitudinal Fissure
o Sometimes called the Interhemispheric Fissure
o Subdivided into 4 major lobes with specialized functions
 Frontal Lobe; Parietal lobe, Temporal Lobe, Occipital Lobe
o Cerebral Cortex  fold increase surface area
 Gyrus: elevated ridge (plural: gyri)
 Sulcus: shallow depression (plural: sulci)
 Fissure: deep depression
What does the brain look like inside?
 The organization of brain is gray-white-gray
 Gray Cortex = neuron cell bodies + synapses
 White Matter = axons
 Gray Nuclei = groups of neurons w/ a common function
Cerebrum: The Limbic System
 Mostly located deep in the temporal lobe
 Learning/memory and emotion
 Hippocampus: Learning/memory
 Amygdala: Emotion (especially fear)
 Nucleus accumbens: reward/addiction
 Amygdala is in the temporal lobe directly in front of the hippocampus
Cerebrum: The Basal Ganglia
 Involved in fine tuning motor activities
 Especially starting & stopping motor activities
 Substantia nigra: death of neurons making dopamine results in Parkinson’s disease
Diencephalon
 Located under the cerebrum
 Links cerebrum & brainstem
 Major components:
o Thalamus sensory relay
o Hypothalamus  homeostasis
o Pituitary gland  regulates hormone production
 Pineal gland  daily rhythms
Diencephalon: Thalamus
 Relays sensory info to cortex
 Relays motor info between cerebellum & cerebral cortex
Diencephalon: Hypothalamus and Pituitary Gland
 Hypothalamus  homeostasis
o Autonomic function
o Hormone production
o Emotion
 Pituitary Gland
o Major endocrine gland
Diencephalon: Pineal Gland
 Produces hormone Melatonin
 Regulates sleep/wake “cycle” Circadian (daily) rhythms
Cerebellum
 Second largest part of brain
 Coordinates body movements
 2 Hemispheres (just like the cerebrum)
 Covered with cerebellar cortex (just like the cerebrum)
Brainstem: Controls the daily functions that keep you alive
 Most cranial nerves attach to brainstem
 Processes information between spinal cord & cerebrum/cerebellum
 Tracts that carry information going up to and leaving the cerebral cortex run through the
brainstem
 Includes: midbrain, pons, medulla oblongata
Brainstem: Midbrain
 Also called mesencephalon
 Superior Colliculi – controls eye movement
 Inferior Colliculi – play a role in sound localization
 Substantia nigra – neurons die in Parkinson’s disease
Brainstem: Pons
 Also called metencephalon
 Connects cerebellum to brainstem
 Controls sensory and motor function for the face
Brainstem: Medulla Oblongata
 Also called myelencephalon
 Regulates autonomic functions vital to life: heart rate, blood pressure, breathing and
digestion
Spinal Cord
 Controls sensory and motor function for the body and viscera
 There is no gray cortex in the final cord; it consists of a butterfly-shaped internal gray
matter surround by white matter
 Due to fixation of the tissue, the grey matter appears white and the white matter appears
brown in this photograph.