Brain Bee Book Cards Flashcards
How many Americans are affected by neurological illnesses annually?
50 million
How much does it cost annually to treat neurological illnesses?
$500 billion
How many adults are struck by mental disorders per year?
44 million
How much does it cost to treat adult mental disorders per year?
$148 billion
How much money would be saved if AD was delayed by five years?
$50 billion is annual health care costs
What is the probability that an identical twin will also be affected by a disease that their twin gets?
30-60%
What are four environmental influences on disease?
Exposure to toxic substances, diet, level of physical activity, stressful life events
What is the brain’s ability to modify neural connections?
Plasticity
What is the adult brain’s ability to continually generate new nerve cells?
Neurogenesis
What is one of the most active regions for neurogenesis in the brain? What is it involved in?
The hippocampus; learning and memory
What halts electrical signaling in nerve cells and in targeted doses can be used to shut down cells that send chronic pain?
Tetrodotoxin (TTX); pufferfish poison
What does PET stand for?
Positron emission tomography
What does fMRI stand for?
Functional magnetic resonance imaging
What are two major advances in neuroscience?
How and why neurons die, stem cells
What is the cerebrum associated with?
Higher order functioning, control of voluntary behavior
How do the two hemispheres communicate?
The corpus callosum
What covers the outermost layer of the cerebrum?
Cerebral cortex
What is the cerebral cortex also referred to as?
Gray matter
What is the frontal lobe responsible for?
Initiating and coordinating movements; higher cognitive skills like problem solving, thinking, planning, organizing; personality
What is the parietal lobe responsible for?
Sensory processes, attention, language
What happens if you damage the right side of the parietal lobe?
Difficulty navigating spaces, even familiar ones
What happens if you damage the left side of the parietal lobe?
You might damage the ability to understand spoken and/or written language
What is the occipital lobe responsible for?
Vision, including recognition of shapes and colors
What is the temporal lobe responsible for?
Hearing, integrating information from the other senses, short term memory with the hippocampus, emotional memory with the amygdala
What makes up the forebrain?
The four lobes, the basal ganglia, the thalamus, the hypothalamus
What are the basal ganglia?
Cerebral nuclei that help coordinate muscle movements and reward useful behaviors
What does the thalamus do?
Passes most sensory information on to the cerebral cortex after helping to prioritize it
What is the hypothalamus?
The control center for appetites, defensive and reproductive behaviors, sleep-wakefulness
What makes up the midbrain?
Two pairs of small hills called colliculi and clusters of neurons that regulate activity in widespread parts of the CNS and are thought to be important for reward mechanisms and mood
Tectum and tegmentum
What do colliculi do?
They play a role in visual and auditory reflexes and in relaying that information to the thalamus
What makes up the hindbrain?
The pons, medulla oblongata and cerebellum
What do the pons and medulla oblongata do?
They control respiration, heart rate, and blood glucose levels
What is the cerebellum responsible for?
Coordinated movement and cognitive processes that require precise timing and also play a role in Pavlovian learning
Knowing the difference between picking up an empty water bottle and a full water bottle
What is the spinal cord an extension of?
It is an extension of the brain through the vertebral column
What is the function of the spinal cord
Receiving all sensory information below the head; relaying that information to the brain and cerebral cortex; reflexes in response to pain in response to that information
About how long is the spinal cord?
17 inches (43 cm)
What makes up the CNS?
Forebrain, midbrain, hindbrain, spinal cord
What makes up the PNS?
Nerves and small concentrations of gray matter called ganglia, a term specifically used to describe structures in the PNS
Give one sentence to describe the nervous system
A vast biological computing device formed by a network of gray matter regions interconnected by white matter tracts
What connects the CNS with the parts of the body that interact with the outside world?
The somatic nervous system
What nerves are related to the neck and arms?
Somatic nerves in the cervical region
What nerves are related to the chest?
Somatic nerves in the thoracic region
What nerves are related to the legs?
Somatic nerves in the lumbar and sacral regions
What connects the CNS with internal organs?
The autonomic nervous system
What does the sympathetic NS do?
Mobilizes energy and resources during times of stress and arousal
What does the parasympathetic NS do?
Conserves energy and resources during relaxed states, including sleep
What is the range of neurons in the mammalian brain depending on the species?
100 million to 100 billion
How many disorders of the brain and nervous system are there?
Around 1,000
What is the range of axon length?
Tiny fraction of an inch — three feet (about one meter) or more
What is the name for myelin sheath glia in the CNS and PNS?
Oligodendrocytes and Schwann cells
What is the glia to neuron ratio?
10:1
What are 4 functions of glia?
Transport nutrients to neurons, clean up brain debris, digest parts of dead neurons, help hold neurons in place
What is a nerve impulse?
A rapid reversal in the electrical potential of the membrane as the inside of the neuron switches from negative to positive and that change passes down the axons’s membrane
How fast is an AP?
Several hundred miles per hour
What are the three kinds of cells that might receive chemical signals?
Other neurons, muscle or gland cells
What can a chemical synapse trigger in the target cell?
An AP, muscle contraction, stimulation of enzyme activity, inhibition of NT release
When was acetylcholine (ACh) discovered?
80 years ago
What neurons release ACh? What does that do?
Neurons that are connected to voluntary muscles (causing them to contract), neurons that control the heartbeat and also in many other regions in the brain
Where is ACh synthesized?
Axon terminals
What happens once ACh has bound to receptors?
It is broken down by acetylcholinesterase and resynthesized in the nerve terminal
What is caused when one type of ACh receptor is blocked?
Myasthenia gravis; fatigue and muscle weakness
What neurons are lost in AD?
ACh-releasing neurons
What are the current type of drugs that are usually used to treat AD?
Drugs that inhibit acetylcholinesterase (increasing ACh in the brain)
What are the inhibitory amino acid NTs?
Glycine and GABA (gamma-aminobutyric acid)
What increases the activity of GABA?
Benzodiazepines (e.g. Valium) and anticonvulsant drugs
What happens to GABA in Huntington’s? What does that cause?
Neurons that produce GABA in brain centers that control coordinated movement degenerate, causing uncontrollable movements
What are the excitatory amino acid NTs?
Glutamate and aspartate
What is activated by the excitatory amino acid NTs?
(Among other things) NMDA receptors (connected to learning and memory in development and specification of nerve contacts)
Stimulation vs. overstimulation of NMDA receptors
Beneficial changes in brain vs. nerve cell damage or cell death (what happens as a result of trauma and strokes)
Name 2 catecholamines
Dopamine and norepinephrine
First dopamine circuit
Dopamine circuit that regulates movement, directly related to disease (Parkinson’s)
Second dopamine circuit
Dopamine circuit that is thought to be important for cognition and emotion (schizophrenia)
Third dopamine circuit
Dopamine circuit that regulates the endocrine system, directs the hypothalamus to manufacture hormones and hold them in the pituitary gland to release into the bloodstream or to trigger the release of hormones held within cells in the pituitary
What is levodopa?
Treats Parkinson’s; a substance from which dopamine is synthesized
What diseases show norepinephrine deficiencies? What do these diseases have in common and what does that say about norepinephrine?
AD, Parkinson’s, Korsakoff’s syndrome (cognitive disorder caused by chronic alcoholism); all related to memory loss and decline in cognitive functioning; norepinephrine is therefore probably connected to learning and memory
Norepinephrine is secreted by what nervous system to regulate what?
Sympathetic NS, regulates heart rate and blood pressure
Acute stress releases norepinephrine from what?
Sympathetic nerves and the adrenal medulla
Where is serotonin most often found?
Blood platelets and the lining of the digestive tract
What has serotonin been connected to?
Sleep quality, mood, depression, anxiety
What might be able to manipulate the emotional switches that serotonin controls?
Analogs (chemicals with a similar molecular structure to serotonin)
What is Prozac’s scientific name and what 2 disorders does it treat?
Fluoxetine; depression and OCD
What are peptides?
Short chains of amino acids
Where are peptides synthesized and are there more or less peptides than the other NTs?
The cell body; way more
When were opiate receptors discovered in the brain? Why was this surprising?
1973; meant the brain produced stuff similar to opium
What did scientists name the first natural opiate peptide found? What drug does it resemble?
Enkephalin (“in the head”); morphine
What is morphine?
An opium derivative used to kill pain
What are opioid peptides (opiate peptides naturally produced by the brain like enkephalin) called?
Endorphins (“endogenous morphine”)
What are C fibers? What do they contain? What sensation do they cause? What acts through this pathway?
Tiny unmyelinated sensory nerves; substance P; burning pain; capsaicin (active component of chili peppers)
What are trophic factors?
Small proteins in the brain that are necessary for development, function, and survival of specific groups of neurons
Where are trophic factors made? What do they bind to?
In brain cells; specific neurons that have receptors for them
What disorders/diseases could the study of trophic factors help with?
Brain disorders of development and degenerative diseases like AD and Parkinson’s
What are the chemical signals of the endocrine system?
Hormones
What are the organs and such that are sources of hormones?
Pancreas, kidneys, heart, adrenal glands, gonads, thyroid, parathyroid, thymus, even FAT
How does the endocrine system work?
It acts on neurons in the brain, which controls the pituitary gland
What does the pituitary gland do?
It secretes factors into the blood that act on the endocrine glands to either increase or decrease hormone production
What is the relationship between the pituitary gland and the endocrine system called? What is this important for?
A feedback loop; sex, emotion, responses to stress, eating, drinking, regulation of body functions (growth, reproduction, energy use, metabolism)
What main hormone receptors does the brain have? What does this activate?
Thyroid hormone receptors, steroid hormone receptors; the receptor proteins then bind to DNA and regulate the action of genes
What are the 6 classes of steroid hormones?
Androgens, estrogens, progestins, glucocorticoids, mineralocorticoids, vitamin D
What are steroids synthesized from?
Cholesterol
What other hormones does the brain have receptors for and what do they do?
Metabolic hormones: insulin, insulin-like growth factor, ghrelin, leptin; taken up from the blood and act to change neuronal activity and certain aspects of neuronal structure
What is the main affect of hormones on the brain?
Hormones alter the production of gene products that participate in synaptic transmission as well as the structure of brain cells; this means the brain’s capacity for synaptic neurotransmission changes all the time
What is a stress hormone that inhibits the ability to learn when you’re stressed for prolonged intervals?
The glucocorticoid cortisol
What causes the release of FSH and LH into the bloodstream in both males and females?
The neurons in the hypothalamus produce gonadotropin-releasing hormone (GnRH)
What do FSH and LH stand for?
Follicle-stimulating hormone; luteinizing hormone
What do FSH and LH do in females?
Stimulate ovulation, promote release of ovarian hormones estradiol and progesterone
What do FSH and LH do in males?
Promote spermatogenesis, release testosterone into the bloodstream
What are the sex hormones?
Testosterone, estrogen, progesterone
What do the increased levels of testosterone in males and the increased levels of estrogen in females act on?
They act on the hypothalamus and the pituitary gland to decrease the release of FSH and LH
What causes sexual differentiation?
Sex hormones acting in fetal and early postnatal life, and (maybe) genes on either the X or Y chromosome contribute to the differentiation
What are 2 sex differences in the brain?
Size and shape of brain structures in the hypothalamus and the arrangement of neurons in the cortex and hippocampus
What are the two gas brain messengers?
Nitric oxide and carbon monoxide?
How are gas brain messengers made? How do they work?
They are made by enzymes as they are needed and released from neurons by diffusion (they don’t act at receptor sites), where they act upon chemical targets (like enzymes in the cell)
What are the 4 functions of nitric oxide?
erections, the relaxation that contributes to the normal movements of digestion in intestinal nerves, regulator of cyclic GMP in the brain, neuronal damage (maybe) that follows conditions of excess glutamate (stroke)
What lipids serve as brain messengers?
Prostaglandins, endocannabinoids
What makes prostaglandins?
Cyclooxygenase
What do prostaglandins do?
They induce fevers and generate pain in response to inflammation
What does aspirin do and how does it work?
Aspirin reduces a fever by inhibiting cyclooxygenase
What is the brain’s marijuana?
Endocannabinoids
What do endocannabinoids do?
The control NT release, usually by inhibiting NTs, and can also affect the immune system and maybe other stuff (still being discovered), control of behavior
What causes endocannabinoids to increase in the brain?
Stressful conditions
How can lipid messengers be described?
They are membrane-derived messengers
What are second messengers?
Substances that trigger communication within the cell after NTs have bound to their receptors and triggered a response
What do second messengers do?
They communicate the chemical message from the NTs to the internal cell machinery
What is the “lifespan” of second messenger effects?
A few milliseconds to a few minutes; might also cause long-term NS changes
What is an example of a second messenger?
Cyclic adenosine monophosphate (cAMP)
How is cAMP made?
It is made when norepinephrine binds to its receptors and the activated receptors binds to a G protein, which then causes adenylyl cyclase to convert ATP into cAMP
When does the brain/NS start to develop after birth?
3 weeks
What is an example of a disease that scientists think might be developmental?
Schizophrenia
Genes important for brain development might lead to susceptibility to what disorder?
Autism spectrum disorders
What are the three germ layers (inside out)?
Endoderm, mesoderm, ectoderm
About how many genes does the DNA contain within each human cell?
25,000
Which germ layer produces signaling molecules?
Mesoderm
What do signaling molecules do?
They “turn on” or “turn off” genes
What is neural induction?
Signaling molecules triggering some ectoderm cells to become nerve tissue
What do the leftover cells in the ectoderm that don’t receive any signaling molecules become?
Skin
What determines the “fate” of different cells?
Proximity to signaling molecules
What is an example of a signaling molecule? Where is it secreted from?
Sonic hedgehog; mesodermal tissue under the developing spinal cord
Cells that are closest to sonic hedgehog; cells that are in the middle; cells that are the farthest
A specialized class of glia; motor neurons; interneurons
What occurs after induction? When does migration begin?
Migration; 3-4 weeks after conception
What forms the brain and spinal cord?
Neural plate (then neural tube)
What happens in week seven?
The eyes and the brain’s hemispheres begin to appear
Where do neurons move as they continue to be produces?
They move from the ventricular zone (inner surface) of the neural tube to the marginal zone (border/outer surface)
What happens after neurons stop dividing? Then what?
They form an intermediate zone, where they slowly accumulate as the brain develops; then they migrate to their position with the help of guidance mechanisms
What is the main form of neuron guidance? How do they help?
Glia (90% of the guidance); they project radially from the intermediate zone to the cortex (temporary scaffolding)
What is the name for how migration occurs? What does it refer to?
“inside-out”; the oldest cells form in the innermost layer of the cortex, the youngest form the outermost
How do small inhibitory interneurons (typically found in the CNS) migrate?
They migrate tangentially across the brain
What are 3 outside forces that can affect migration?
Alcohol, cocaine, radiation
What is caused by misplacement (lack of proper neuron migration)?
Mental retardation or epilepsy
What 2 processes allow for neurons to connect?
The growth of dendrites; the growth of axons
What is the term for APs jumping from node to node?
Saltatory conduction (saltatory means “to jump”)
Do APs move faster through myelin or through the nodes?
Myelin
How many neurons survive to function in adulthood?
50%
What is programmed cell death called?
Apoptosis
What is activated in a neuron when it does not receive trophic factors during development?
Apoptosis
What produces trophic factors?
Target tissues
What does each type of trophic factor do?
Supports the survival of a distinct group of neurons
What are trophic factors?
Chemical signals
What does NGF stand for? What is it? What does it do?
Nerve growth factor; trophic factor; sensory neuron survival
What was discovered about injuries/neurodegenerative diseases and apoptosis?
Injuries and some neurodegenerative diseases kill neurons through apoptosis (instead of directly)
What is pruning also referred to as?
Paring back
Does most paring back occur before or after birth?
In the embryo
What are critical periods characterized by?
High learning rates and enduring consequences for neuronal connectivity
What happens after a critical period?
Synapses are lost, the remaining ones are stronger and more precise
What does each critical period period do?
It develops a certain brain function
When is the last critical period? What brain function does it develop?
Early 20s; prefrontal cortex/frontal lobe
When are most critical periods?
Early postnatal life
What is a phrase that represents how paring back works? Why?
“Use it or lose it”; connections not used in childhood permanently damage them (monkey that had an eyepatch as a baby)
Heightened activity during critical periods can lead to what? Does it go away?
Childhood disorders such as epilepsy; many types of epilepsy fade away by adulthood
What is the brain’s ability to modify itself?
Plasticity
What are the two categories of plasticity?
Experience-expectant, experience-dependent
What is experience-expectant plasticity?
Plasticity that requires environmental stimulation (finches need to hear adult songs in childhood)
On what organisms are initial stages of visual transduction studied?
Drosophila and mice
What is visual transduction?
How light is converted into electrical signals
On what organisms is visual processing studied?
Monkeys and cats
What two parts of the eye does light first pass through?
Cornea then lens
How much of the focusing does the cornea do?
Three-quarters
What does the lens do?
Adjusts the focus
What is the retina?
A sheet of photoreceptors that line the back of the eye
Is the retina part of the PNS or CNS?
CNS
How do photoreceptors gather visual information? What happens after that?
Absorbing light and sending electrical signals to other retinal neurons for initial processing and integration; signals sent to other parts of the brain via the optic nerve (there the image is actually processed)
Do objects to the right of the center project images to the right part or the left part of the retina?
Left
Do objects above the center project images to the top part or the bottom part of the retina?
Bottom
What is the size of the pupil controlled by?
Iris
What does the size of the pupil control?
How much light enters the eye
What is the shape of the lens controlled by? What does this allow for?
Muscles right behind the iris; near or far object ban be brought into focus on the retina
What is vision using two eyes called?
Binocular vision
About how many fibers does each optic nerve have?
A million
Where do (some) nerve fibers cross over? What does this allow for?
The optic chiasm; both sides of the brain can receive signals from both eyes
The left half of a scene is registered on what side of the retina and what hemisphere of the cerebrum? What else does this apply to?
Right, right; movement and touch
What is the intermediate way station between the retina and the visual cortex?
The LGN (lateral geniculate nucleus)
Myelination increases AP speed by a factor of what?
100x
If neurons are cultured with muscle tissue, what NT do they produce?
Acetylcholine
If neurons are cultured by themselves, what NT do they produce?
Norepinephrine
What molecules guide (by attracting/repelling) axon growth?
Signaling molecules
Name three signaling molecules.
Netrin, semaphorin, ephrin
How many semaphorins have been identified?
At least 15
How many ephrins have been identified?
At least 9
What guides axon growth (part of the neuron)?
Growth cones
In what organism was the first netrin discovered? What did it do?
A worm; guided neurons around the worm’s “nerve ring”
How do growth cones know where to go?
They have receptors that receive the different signaling molecules
What molecules (by attracting/repelling) make neurons connect and form synapses?
Recognition molecules
What happens to the tiny portion of the axon once it contacts a dendrite?
It becomes specialized for NT release
What happens to the tiny portion of a dendrite once it contacts the axon?
It becomes specialized to receive NTs
What passes between the sending and receiving cell to ensure proper contact is made?
“Special molecules”
What coordinates the maturation of the synapse once it has been formed? Defects have been related to susceptibility to what?
“Special molecules”; disorders such as autism
About how many photoreceptors are in each eye?
125 million
What are the two major types of photoreceptors?
Rods and cones
Rods constitute what percent of photoreceptors?
95%
What are the 3 types of cones?
Red, green, blue
What is the central part of the retina where light is focused? What cones does it contain?
Fovea; red and green
What is the area around the fovea called? What is it critical for?
Macula; reading and driving
What is the leading cause of blindness among the elderly population in developed countries?
Macular degeneration (death of photoreceptors in the macula)
What does the first layer of the retina consist of?
Rod and cone photoreceptors
What does the middle layer of the retina consist of?
Interneurons
What does the third layer of the retina consist of?
Multiple different types of ganglion cells, specialized neurons near the inner surface of the retina
What do the axons of the ganglion cells in the retina form?
The optic nerve
Near the center of the gaze, ganglion cells receive input from how many cones? What does this allow for?
One, at most a few; high visual acuity, fine detail
Near the margins of the gaze, ganglion cells receive input from how many rods and cones? What does this cause?
Many rods and cones; causes the lack of detail at the edges of our vision
What is the region of visual space providing input to a visual neuron called?
It’s receptive field
When is a visual neuron’s receptive field activated?
When light hits a tiny region in the center of the field
When is a visual neuron’s receptive field inhibited?
When light hits the area surrounding the center of the field
If light covers the entire receptive field, how does the cell respond?
Weakly
Visual information from the retina is relayed through what to what?
Through the LGN of the thalamus to the primary visual cortex (thin sheet of tissue in the occipital lobe)
How thin is the primary visual cortex?
Less than one-tenth of an inch thick
What does the middle layer of the primary visual cortex receive messages from?
The LGN
What kind of response is seen in the middle layer of the primary visual cortex?
Responses similar to those in the retina and LGN
What kind of stimuli do the cells in the top and bottom layers of the primary visual cortex respond to?
Stimuli in the shape of bars or edges and those at a particular angle (orientation)
Visual signals are fed into at least how many separate processing systems? What do they process?
3; shape, color, and movement, location, and spatial organization
Does the perception of movement, depth, perspective, shading and texture depend primarily on light intensity or color?
Light intensity
When can major regions of the brain be recognized after conception?
4 weeks
When can gyri/sulci be recognized after conception?
6 months
What is the cause of an inherited form of blindness that may be corrected by gene therapy?
Mutations in the RPE65 protein
What is the condition where the eyes are not properly aligned and point in different directions?
Strabismus (cross-eye)
What happens to children with strabismus?
Since they cannot fuse the images in the two eyes, they favor one eye and the other “dies”
About when does the blindness in one eye become permanent with strabismus?
8 years
When did strabismus used to be treated? When is it treated now?
Waited until kids were older than 4; now before age 4 (when normal vision can still be restored)
What makes up the external ear?
The pinna (earlobe) and the external auditory canal
The external ear funnels sound into what? What does the funneling do?
The tympanic membrane (eardrum); makes it vibrate
What is the malleus (hammer) attached to and what does it do?
The tympanic membrane; transmits the vibration to the incus (anvil)
What does the incus (anvil) do?
Passes the vibrations on to the stapes (stirrup)
What does the stapes (stirrup) do?
Pushes on the oval window, which separates the air-filled middle ear from the fluid-filled inter ear to produce pressure waves in the inner ear’s snail-shaped cochlea
Where does the separation of frequencies occur?
The cochlea
What are the two membranes of the cochlea called?
The basilar membrane (has the hair cells) and the tectorial membrane (has the fluid)
How does the cochlea work?
It is tuned along its length to different frequencies, so that a high note causes one part of the basilar membrane to vibrate and a low note causes another part to vibrate
What is riding on the vibrating basilar membrane?
Hair cells topped with microscopic bundles of hairlike stereocilia, which are deflected by the overlying tectorial membrane
How many fibers does the auditory nerve have?
30,000
What do the hair cells in the inner ear convert the vibrations into? What does this do?
Electrical signals; excites the fibers of the auditory nerve
Where does the auditory nerve carry its signals to?
Brainstem
How many frequencies does each auditory nerve fiber respond to?
One
What is the part of the brain involved in perceiving sound?
The superior temporal gyrus (auditory cortex)
In the auditory cortex, proximal neurons tend to respond to similar what but different what?
Similar frequency; different combinations of tones
What is the left auditory cortex specialized for?
Perceiving and producing speech
What can damage to the left auditory cortex cause?
Someone who can hear but not understand language
Sound is the perception of what?
Changes in air pressure
Taste and smell is the perception of what?
Chemicals in the air and in food
What is flavor a combination of?
Taste and smell
What are the five tastes?
Sweet, salty, sour, bitter, umami (“savory” in Japanese)
What are the small protuberances on the tongue that taste buds are embedded in?
Papillae
What are the chemicals detected by taste buds? Name 3 examples.
Tastants; sugars, salts, acids
Besides the tongue, where are taste buds found?
The back of the mouth and on the palate
How many taste buds does a person have?
5,000-10,000
How many specialized sensory cells does each taste bud have?
50-100
When the gustatory cells in taste buds are stimulated, what sends impulses to where? Where are the impulses then relayed to? Then where?
Cranial nerves (that are gustatory nerves), medulla; thalamus; orbital cortex
What is another word for “taste nerve”?
Gustatory nerve
What are airborne odor molecules called?
Odorants
What are odorants detected by?
Receptor proteins found on hairlike cilia at the tips of specialized sensory neurons located in a small patch of mucus membrane lining the roof of the nose
What do the axons of olfactory neurons have to pass through to enter the olfactory bulbs?
A thin layer of bone
Since an odorant acts acts on more than one receptor (to varying degrees), how do we differentiate between them?
Each odorant has its own “pattern of activity” that is sent by the nerve fibers to the olfactory bulb
When an olfactory pattern of activity enters the olfactory bulb, what is created by neurons there?
A spatial map of the odor
Impulses stimulated by an olfactory spatial map go where? Then where?
The primary olfactory cortex; the orbital cortex
What is another way to say “the back of the underside”?
Orbital
In hairy skin areas, what do some touch receptors consist of?
Webs of sensory nerve cell endings wrapped around the base of the hairs
Signals from touch receptors pass via what to what? There they synapse with other nerve cells that send the information via what to what?
Sensory nerves to the spinal cord; thalamus to the sensory cortex
What does it mean to say that touch is topographic? What is this brain map called?
Larger areas of the sensory cortex are devoted to sensitive areas of the body and smaller areas to less sensitive areas; the homunculus
What test do neurologists use to measure sensitivity? How does the test work?
They determine the patient’s two-point threshold by poking them at two different places and finding the distance necessary in order for the individual to distinguish that it’s two stimuli, not one
What are the sensory fibers that respond to nerve-damaging stimuli?
Nociceptors
What is an example of an itch-causing chemical that is produced by itch nociceptors?
Histamine (bug bites/allergies)
What is another adjective for painful?
Noxious
What do prostaglandins do?
Enhance the sensitivity of receptors to tissue damage (can ultimately induce more intense pain)
What clinical condition do prostaglandins contribute to?
Allodynia (harmless stimuli is painful)
Persistent injury can lead to what?
Hypersensitivity; amplification and prolonging of the “pain” signal
Pain and itch messages are transmitted by what to where?
Small, myelinated fibers and C fibers (small, unmyelinated fibers) to the spinal cord
Myelinated nerve fibers send what kind of pain?
Fast and sharp (pinprick)
C fibers send what kind of pain?
Slow and dull (capsaicin)
Where is the pain/itch message received in the brain (from the spinal cord)?
The thalamus/cerebral cortex
Pain messages can be suppressed by systems (descending or ascending?) that originate from where? They suppress the pain signals going from what to where?
Descending systems; within the gray matter in the brainstem; from the dorsal horn of the spinal cord to higher brain centers
Some of the descending anti-pain neuron systems use naturally occurring chemicals called?
Endogenous opioids (endorphins)
What chemical are endorphins functionally similar to?
Morphine
Where are opioids medically distributed to (often after surgery)? Why?
The spine; dense distribution of opioid receptors in the spinal cord horn
Is there one single area of the brain that generates pain?
No
What did H.M. develop as a child? What did he have removed? What was the result?
Severe epilepsy; the medial regions of his temporal lobes; greatly alleviated the seizures but gave him amnesia (he could only remember events/things for a few minutes)
