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The Nervous System - Macro


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Cerebrum
The largest division of the brain. It is divided into two hemispheres, each of which is divided into four lobes.
Cerebral Cortex
The outermost layer of gray matter making up the superficial aspect of the cerebrum.
Gyri
Elevated ridges "winding" around the brain.
Why does the brain have gyri?
The brain is folded to increase the amount of cells, thus increasing the amount of connections we make between neurons.
Sulci
Small grooves dividing the gyri.
Central Sulcus
Separates the frontal and parietal lobes.
Fissures
Like sulci but deeper. Deep grooves, generally dividing large regions/lobes of the brain.
Examples of Fissures
1) Central Sulcus, 2) Transverse Fissure, 3) Sylvian/Lateral Fissure 4) Longitudinal Fissure
Longitudinal Fissure
Divides the two Cerebral Hemispheres
Transverse Fissure
Separates the Cerebrum from the Cerebellum
Sylvian/Lateral Fissure
Divides the Temporal Lobe from the Frontal and Parietal Lobes
Cerebellum Functions
Lower brain functions, life support functions. TBC
Features of the frontal lobe
1) Next to bone called frontal bone, 2) Right and left lobes each have unique functions.
Functions of Frontal Lobe
Higher brain activity, what to do and how to do it.
Name the four lobes of the brain. (Alphabetical Order)
Frontal, Occipital, Parietal, Temporal
Where is the frontal lobe located?
The Frontal Lobe of the brain is located deep to the Frontal Bone of the skull.
Functions of the frontal lobe
Memory formation, emotions, personality, decision making, reasoning.
Personality
How you recognize you as you, damage leads to dramatic changes in the personality.
Is the frontal lobe the only place responsible for memory?
No, the frontal lobe is responsible for components of memory formation, but memory also happens in other places.
What happens to emotions when the frontal lobe is damaged?
Person is not able to respond to emotions. 1) A psychopath has underdeveloped frontal lobes and thus does not have empathy. 2) CPO’s of successfully financial companies have underdeveloped frontal l
What happens when the right frontal lobe is damaged?
Person can’t bring arm out, muscles of extension are out; can only have flexion.
Regions of the frontal lobe.
1) Primary motor cortex (precentral gyrus), 2) Broca's area, 3) Orbital frontal cortex.
What nerve runs through the frontal lobe?
Olfactory Bulb (Cranial Nerve I)
olfactory bulb
Sensation of smell.
primary motor cortex
Volitional motion.
Aphasia
Inability to speak.
Broca's Area
Controls facial neurons, speech, and language comprehension. Located on Left Frontal Lobe.
Broca's Aphasia
Comprehend speech. Decreased motor ability to speak
Give an image for Broca's Aphasia.
A broken mouth.
Why would a "broken mouth" be attributed to the frontal lobe?
The frontal lobe controls movement.
Contralateral control?
The left brain "talks" to the right side of the body and visa-versa.
Can Broca aphasiac's understand speech?
Yes they can understand speech
Are there exceptions to the brain's contralateral control?
Yes! The olfactory nerve does not cross.
What are the implications of the olfactory nerve not crossing?
Input smells differently to each nostril because different parts of the brain process the input.
Where is the site of frontal lobotomies?
Orbitofrontal Cortex.
What are the desired effects of frontal lobotomies?
Diminished Rage - Decreased Aggression - Enhanced Emotional Responses.
What are the possible side effects of frontal lobotomies?
- Epilepsy - Poor Emotional Responses - Perseveration (Uncontrolled, repetitive actions, gestures, or words)
What is a frontal lobotomy?
Removal of all or part of the frontal lobe.
How and why were lobotomies done?
The surgeon drove an icepick through the eyeball and swirled it around. Nerve cells snapped in half, thus dramatically changed their behavior. Lobotomies were done before thorazine and hal
What is a chemical lobotomy?
Drug treatment. Halidol and thorazine.
What are the effects of a lobotomy?
Lobotomies knock out motor and reasoning faculties, but also quells personality issues. Afterwards the patient is likely to be found sitting in corner drooling, might be able to walk and use the toile
What is the consistency of the brain?
It is like thick pudding.
Where is the parietal lobe of the brain located?
Deep to the parietal bone of the skull. (Right on top.)
What are the two major functions/actions of the parietal lobe?
1) Senses and interprets sensations (integration of sensory data), 2) Spatial awareness and perception (figures out where it is.)
Detail of parietal lobe function: 1) Sensing and Interpreting sensations
How your brain figures out what sensation means. Is it a little pain, a lot of pain, should I punch someone, who do I have to talk to, do I have to move my hand from the hot stove.
Proprioception
Tells your brain where you are in space. Awareness of body/ body parts in space and in relation to each other.
Where does proprioception usually occur?
Predominately occurs in the joint surfaces.
How does proprioception work?
We have a map up there, a sensory map on the parietal lobe which tells the rest of the brain where the sensation is coming from.
What are the cortical regions of the parietal lobes?
1) Primary Somatosensory Cortex (Postcentral Gyrus), 2) Somatosensory Association Cortex, 3) Primary Gustatory Cortex.
Where is the Primary Somatosensory Cortex (Postcentral Gyrus) located?
It is located posterior to the primary motor cortex, just behind the central sulcus.
What does the primary somatosensory cortex do?
It is the site involved with processing of tactile and proprioceptive information.
What is the role of the Somatosensory Association Cortex?
It functions as an assistant to the primary somatosensory cortex. It assists with the integration and interpretation of sensations relative to body position and orientation in space. May assist with v
What else might the Somatosensory Association Cortex do?
It may a assist with visuo-motor coordination.
What is the function of the primary gustatory cortex
Primary site involved with the interpretation of the sensation of Taste. Does it taste good, bad or disgusting? Necessary for survival.
Do patients feel pain in their brains when they are operated on?
No! There are no pain sensors in the brain tissue. Most of the time patient is awake for neurosurgery.
Where is the occipital lobe located?
Posterior to the parietal lobe. The Occipital Lobe of the Brain is located deep to the Occipital Bone of the Skull.
What is the occipital lobe's primary function?
Its primary function is the processing, integration, interpretation, etc. of VISION and visual stimuli.
What does the occipital lobe "ask?"
What does the visual data mean? Is this a mate, a mouse, a car, am I in danger?
What are the cortices of the occipital lobe?
1) Primary Visual Cortex, 2) Visual Association Area
What does the primary visual cortex do?
This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc.
What does the visual association area do?
Interprets information acquired through the primary visual cortex.
What is the most posterior part of your skull?
Occipital Lobe.
Where are the temporal lobes located?
The Temporal Lobes are located on the sides of the brain, deep to the Temporal Bones of the skull.
What integral roles do the temporal lobes play?
1) Hearing - Organization/Comprehension of language, 2) Information Retrieval - (Memory and Memory Formation)
Is hearing processed contra-laterally or uni-laterally?
Hearing is processed contra-laterally; left temporal lobe processes right ear hearing.
What is the function of the temporal lobe in the production of memories?
To really make memories work effectively, true memory formation happens in the temporal lobe, converts short term memory into long term memory. Comprehension of language, memory formation.
What does neuroplasticity mean?
Neuroplasticity means that it is never just one part of the brain that does the thing. You can train other parts of the brain to take over functions if one part of the brain is damaged.
What are the cortical regions of the temporal lobes?
1) Primary Auditory Cortex, 2)Primary Olfactory Cortex, 3) Wernicke’s Area.
What is the function of the primary auditory cortex?
Responsible for hearing.
What is the function of the primary olfactory cortex?
Interprets the sense of smell once it reaches the cortex via the olfactory bulbs. (Not visible on the superficial cortex).
What is the function of Wernicke's area?
Language comprehension. Located on the Left Temporal Lobe.
What is Wernicke's Aphasia?
Language comprehension is inhibited. Words and sentences are not clearly understood, and sentence formation may be inhibited or non-sensical.
Wernicke's Aphasia versus Broca's Aphasia
Wernicke's aphasiacs do not understand language nor can communicate. (Left temporal lobe.) Broca's aphasiacs CAN understand language, but have mechanical reasons for not speaking. (Left parietal lobe.
Arcuate Fasciculus
A white matter tract that connects Broca’s Area and Wernicke’s Area through the Temporal, Parietal and Frontal Lobes. Allows for coordinated, comprehensible speech. Damage may result in Conduction a
Conduction Aphasia
Where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech.
What happened to Phineas Gage? Part 2
On one of these instances, the detonation occurred prior to his expectations, resulting in a 42 inch long, 1.2 inch wide, metal rod to be blown right up through his skull and out the top. The rod ent
Who was Phineas Gage? Part 1
Phineas Gage was a railroad worker in the 19th century living in Cavendish, Vermont. One of his jobs was to set off explosive charges in large rock in order to break them into smaller pieces.
Did Phineas Gage loose consciousness? Vital signs?
Gage never lost consciousness, or quickly regained it (there is still some debate), suffered little to no pain, and was awake and alert when he reached a doctor approximately 45 minutes later. He had
How was Phineas Gage affected by the accident? Part 4
He survived and went home with a headache. He remained conscious, had no pain, never passed out. Then turned into an asshole, argumentative, difficult to get along with.
Recalling what you have just learned regarding the frontal lobe, what possible problems or abnormalities may Gage have presented with subsequent to this type of injury (remember the precise locati
1) Gage’s personality, reasoning, and capacity to understand and follow social norms had been diminished or destroyed.
More of Gage's possible problems or abnormalities:
2) He illustrated little to no interest in hobbies or other involvements that at one time he cared for greatly.
More of Gage's possible problems or abnormalities:
3) ‘After the accident, Gage became a nasty, vulgar, irresponsible vagrant. His former employer, who regarded him as "the most efficient and capable foreman in their employ previous to his injury," re
It is suggested that Gage’s injury inspired the development of what at one time was a widely used medical procedure. What might this procedure be, and how does it relate to Gage’s injury?
The frontal lobotomy. This has been used with the intention to diminish aggression and rage in mental patients, but generally results in drastic personality changes, and an inability to relate social
Are lobotomies accepted and performed today? Are there alternatives to surgical lobotomies?
This procedure is largely frowned upon today, with the development of neurological drugs as treatments.
What is a homunculus?
A very small human or humanoid creature. In anatomical terms, examples include: graphic representation of the regions of the Primary Motor Cortex and Primary Sensory Cortex.
Why are the graphical maps disproportionate maps of the brain?
Because some parts of the body require a lot of control for the brain for movement, therefore the "wiring" is disproportionate.
Note about homunculus.
Homunculus literally means “little person,” and may refer to one whose body shape is governed by the cortical area devoted to that body region.
What is meant by depicting these body parts in such outrageous proportions in the homunculus?
These outrageous proportions depict the cortical area devoted to each structure.
Examples of outrageous proportions in the homunculus:
Your hands require many intricate movements and sensations to function properly. This requires a great deal of cortical surface area to control these detailed actions.
What is the back given a smaller proportion in the homunculus?
Your back is quite the opposite from your hands. Your back requires limited cortical area to carry out its actions and functions, or detect sensation.
Explain how the homunculus works. What does it represent?
The homunculus shows that there is a part of the brain that just listens to the hand, the face, tongue, knee, the foot, etc.
Why do you think the brain is paying so much attention to the face, foot, hand and tongue?
There is much more sensation in the foot, hand and tongue then the other less represented areas. The face makes many fine motor movements, which are highly differentiated: grimaces, frowns, etc.