Chapter 11: Nervous System II: Divisions of Nervous System
Short Term Memory
-Working memory -Closed neuronal circuit -Circuit is stimulated over and over -When stimulation ceases, memory also, does, unless it enters long-term memory via memory consolidation
What does the limbic system consist of?
Portions of frontal lobe Portions of temporal lobe Hypothalamus Thalamus Basal nuclei Other deep nuclei
Motor Areas (Pre-central sulcus)
Primary motor areas Broca's area Frontal eye field
Implicit (nondeclarative)
Procedural memory Associative learning Non-associative learning
3 major areas of Cerebrum
Sensory Moto Association *referred to as a cortex or cortices
What do both hemispheres participate in?
Sensory analysis, storing memories, and skeletal muscle control
How does ganglia control certain voluntary muscular activities?
-Via connections w/ motor cortex, thalamus, and cerebellum -Dysfunction in these nuclei associated w/ parkinson's, huntington's, ADHD, OCD
White Matter
Axons or nerve tracts
Functions of the Limbic System
Controls emotions (amygdala) Produces Feelings Interprets sensory/olfactory impulse
Structure of Cerebrum
Corpus Callosum Gyri Sulci Fissures
What does the fibers cross over?
Cross over each other in brainstem from one side of the other (decussation): Left side of body controlled by right
Crossed Extensor Reflex (example)
Crossing of sensory impulses within the reflex center to produce an opposite effect *Some interneurons inhibit antagonistic extensor muscles ipsilaterally and regulate contralateral leg muscles to maintain balance
What do the fibers of the corpus callosum allow for?
Dominant hemisphere to control/ receive motor, sensory, and decision making tasks
DAVE
Dorsal Afferent, Ventral Efferent
Types of Long-term memory
Explicit (declarative) Implicit (nondeclarative)
Parts of Cerebrum (forebrain)
Frontal Parietal Occipital Temporal Insula
Lobes of Cerebrum
Frontal lobe Parietal lobe temporal Occipital Insula aka 'island of reil'
Types of association areas
Frontal lobe associations areas Parietal Lobe Temporal Lobe Occipital lobe
Primary Motor Areas
Frontal lobes control voluntary muscles
Sulci
Grooves in gray matter (central sulcus)
What does the hypothalamus regulate?
HR and BP eating drinking temp circadian rhythms
What do association areas provide?
Higher intellectual processes Memory, reasoning, verbalization, judgement, emotions
Brainstem
Hindbrain and midbrain combined
What do the 2 enlargements supply?
Nerves to upper and lower limbs
Visual Area
Occipital Lobe Interprets vision
Periaqueductal Gray
Pain perception, MORs
Cutaneous Sensory area/ cortex
Parietal lobe Interprets sensations on skin
Amygdala
Part of the emotional control center of the brain and assigns an emotional 'value' to memory
What does brain stem control?
-The programmed, automatic behaviors critical to survival -Pathway for fiber tracts between the higher and lower neural centers and is associated w/ 10 of 12 cranial nerves -Connects brain to spine
What side is more dominant?
The left hemisphere is dominant in most individuals
What does the spinal cord allow?
Two-way communication between brain and the body
Superior Colliculus
Visual system, pointing
Finiculi
White matter columns forming tracts
Memory
a specific circuit of neurons which communicate to each other
Frontal Lobe association areas
concentrating planning complex problem solving emotional behavior
Withdrawal Reflex
flexor Reflex Prevents or limits tissue damage 3 nerve arcs
What happens if a memory is consolidated?
it is stored in various association areas of the cerebral cortex
Cerebral Cortex
-Thin layer of gray matter that constitutes the outermost portion of cerebrum (2-5mm think) -Contains 75% of all neuron cell bodies NS
Parietal Lobe association areas
-Understanding speech -choosing words to express thoughts and feelings -awareness of object and body forms
What does non-dominant hemisphere control?
-Nonverbal tasks -Motor tasks -Understanding and interpreting musical and visual patterns -Provides emotional and intuitive thought processes
Association Areas
-Regions that are not primary motor or primary sensory areas -Widespread throughout the cerebral cortex
What strengthens synaptic connections?
-Repeated stimulation of neuronal circuits
Explicit (declarative)
-Semantic memory -episodic memory
Thalamus
-Sensory inputs converge here (all but smell) are filtered and passed to the cerebral cortex for processing -Lots of connection with cortex -> exit ramp from spine
Spinal Cord
-Slender column of nervous tissue continuous w/ brain and brainstem -Extends downward through vertebral canal -Filum Terminale
Choroid Plexus
-Specialized capillaries -Releases cerebrospinal fluid
What does Dominant hemisphere control?
-Speech -Writing -Reading -Analytical skills -Computational skills
The midbrain
-Tectum (dorsal) and tegmentum -Periaqueductal gray -Superior colliculus -Inferior colliculus -Motor Nuclei
Functions of Brain
*Often in nerve centers of nuclei -Interpret sensations -Determine perception -Store memory -Reasoning -Make decisions -Coordinate muscular movements -Regulate visceral activities -Determine personality
Dura Mater (outer)
-"Tough mother" -Venous Sinuses
Pia Mater (inner)
-"faithful mother" -Encapsulates blood vessels
Arachnoid Mater
-"spiderweb-like" -Space contains cerebrospinal fluid (CSF)
Ventricles of the Brain
-4 -Interconnected cavities within cerebral hemispheres and brain stem -Continuous w/ central canal of spinal cord -Filled w/ cerebrospinal fluid (CSF) -Interventricular foramen (lats to 3rd) -Cerebral aqueduct (3rd to 4th)
Hypothalamus
-A collection of nuclei -Connected to pituitary gland -Controls autonomic nervous system
Meningitis
-An infection of the meninges -Bacterial and viral -Affects arachnoid and/ or pia maters
Occipital Lobe association areas
-Analyze and combine visual images w/ other sensory experiences -Face recognition
Reflexes
-Automatic, subconscious responses to stimuli wthin or outside the body -Maintain homeostasis ; carry out automatic actions (swallowing, sneezing, vomiting) -Simple reflex arc (sensory- motor) -Most common reflex arc (sensory- association- motor)
Long Term Memory
-Changes in the structure or function of neurons -Enhances synaptic transmission -LTP- long term potential -Allow consolidation
Cerebrospinal Fluid
-Circulates in ventricles, central canal of spinal cord, and subarachnoid space -Surrounds brain and spinal cord (blood= CSF barrier)
What is cerebrospinal fluid?
-Clear fluid similar to blood plasma -Only about 140 ml -Nutritive and protective -Reflects composition of body fluid -CSF floats the brain
Ascending Tracts (Axons)
-Conduct sensory impulses to the brain
Functions of Spinal Cord
-Conduit (pathway) for nerve impulses to and from brain and brainstem -Center for spinal reflexes (reflex arcs)
Memory
-Consequence of learning -Learning is the acquisition of new knowledge -Memory is the persistence of that knowledge and the ability to recall it at a later time
Layers of Meninges
-Dura Mater (outer) -Arachnoid mater -Pia Mater (inner)
Evolutionary Development of Brain
-Hindbrain (oldest) -Midbrain -Forebrain (most recent to develop)
Temporal Lobe association areas
-Interpret complex sensory experiences -Help understand speech and to read -Store memories of visual scenes music, and complex patterns
Fissures
-Longitudinal: separates the cerebral hemispheres -Transverse: separates cerebrum from cerebellum
Effects of Meningitis
-Loss of vision and hearing, paralysis, mental retardation, death
Meninges
-Membranes of CNS -Protects CNS
What are the 4 ventricles?
-lateral ventricles (2) (first= left and second = right) -Third ventricle (below Corpus callosum) -Fourth Ventricle (brainstem)
How many segments in spinal cord?
31 segs each giving rise to a pair of spinal nerve
Filum Terminale
A thin cord of CT attaches to upper surface of coccyx
Frontal eye field
Above Broca's area Controls voluntary movements of eyes and eyelids
What is down with excess or wasted CSF?
Absorbed by arachnoid granulations
What do association do?
Analyze and interpret sensory experiences
Broca's Area
Anterior to primary motor cortex Usually in left hemisphere controls muscles needed for speech Connected to Wernicke's
Sensory area for smell
Arises from centers deep within the cerebrum
Hindbrain
Basic, life-sustaining functions
Where does the spinal cord start and stop?
Begins at foramen magnum and terminates at the first and second lumbar vertebrae (L1/L2) interspace
Diencephalon
Between cerebral hemispheres and above the brainstem Surrounds the third ventricle
What does CNS consist of?
Brain and spinal cord
What does the brainstem connect to?
Brain to the spinal Cord
Gyri
Bums or convolutons
How does CNS communicate w/ PNS?
By way of spinal cord
Gray Matter
Cell bodies and interneurons
Major Parts of the brain
Cerebrum Diencephalon (forebrain) Cerebellum Brainstem (hindbrain)
Descending Tracts
Conduct motor impulses from the brain to motor neurons reaching muscles and glands
Corpus Callosum
Connects cerebral hemispheres (a commissure)
Forebrain
Includes the cerebral hemispheres
What do sulci and gyri act to do?
Increase surface area/volume of brain (more neurons)
Functions of Cerebrum
Interpreting impulses from sense organs Initiating voluntary movements Storing information as memory and retrieving stored information Reasoning Seat of intelligence and personality
Ganglia
Masses of gray matter deep within cerebral hemisphere (caudate, nucleus, putamen, and globus pallidus) -Produce dopamine Control certain voluntary muscular activities
Parts of Brainstem (hindbrain)
Midbrain Pons Medulla Oblongata
Regions of the brain stem (superior to inferior)
Midbrain Pons Medulla Oblongata *these parts consist of many tracts of nerve fibers and nuclei
Forebrain
More complex functions
Sensory Area for taste
Near base of the central sulcus
Auditory Area
Temporal lobe Interprets hearing
Sensory speech area (wenicke's area)
Temporal/ parietal lobe Usually left hemis Understanding and formulating language
Parts of Diencephalon
Thalamus Hypothalamus
Hippocampus
Thought to be the brain center for generation of memories -temporal lobe