ch 7 other sensory systems

inner ear

includes the oval window -receives vibrations from the tiny bones of the middle ear, and travels to the cochlea, which contains three fluid-filled tunnels (the scala vestile, scala media, and scala tympani) 1)stapes causes it to vibrate setting in motion all the fluid in the cochlea 2)auditory receptors, hair cells, lie between the basilar membrane and tectorial membrane in the cochlea 3) when fluid in the cochlea vibrates, a shearing action occurs which stimulates hair cells and then these stimulate auditory nerve cells

frequency

number of compression per second, measured in hertz(Hz) of a sound

pitch

the perception of frequency about sound -higher the frequency, higher the pitch -can mostly hear vibrations from 15 to 20,000 Hz -children hear higher frequencies than adults do because ability to receive higher frequencies decreases with age

bitter receptors

sensitive to a wide range of chemicals that degree in toxicity -25 different types of bitter receptors -we cannot detect very low concentrations of bitter substances

touch sensation

the somatosensory cortex responds to the touch sensation of the tongue

through which mechanism do we perceive low frequency sounds?

basial membrane. close to the apex, farthest from the cochlea

opiate drugs

block the receptors of substance P in the spinal cord and in the gray area of the midbrain

pain sensilization

body releasing histamines, nerve growth tissue, and other things that are necessary to prepare the body -certain receptors become potentiated after intense barrage of painful stimuli leading to chronic pain later

capsaicin

chemical that makes jalapenos and similar peppers hot -rubbed into sore shoulder to produce a burning sensation followed by decreased pain

sourness receptors

close potassium channels when acid binds to receptors which prevents K+ from leaving the cell

how is the auditory cortex similar to the visual cortex?

contains area MT responsible for detecting motion of sound and imagery -needs experience to develop normally

pain pathway

cross to a tract ascending the contralateral side of the spinal cord -somatosensory cortex responds to painful stimulus, memories of pain, and signals that warn of impending pain -central nuclei of the thalamus, amygdala, hippocampus, prefrontal cortex, and cingulate cortex are associated with emotional associations

placebos

drug or other procedure with no pharmocological effects -relieve pain -effects mostly on emotional responses not just the sensation itself -decrease the response in the cingulate cortex but not in the somatosensory cortex -relieve pain by increasing the release of opiates and partially by increasing relaes of dopamine

across fiber pattern

each receptor responds to a wider range of stimuli and a given response by a given axon means little expect in comparison to what other axons are doing

taste sensation

the insula ( part of the cerebral cortex) -each hemisphere responds to the ipisilateral side of the tongue

substance P

the neurotransmitter that is released when you have strong pain -a co-transmitter with glutamate used by unmyelinated or thinly myelinated axons to relay pain info to the spinal cord

labeled-line stiumulus

each receptor would respond to a limited range of stimuli and sends a direct line to the brain so the meaning depends on which neurons are active

pain

experience evoked by harmful stimulus directing our attention towards danger -pain sensation begins with least specialized of all receptors. some pain receptors also repsond to acids, heats, and cold -chemicals irritate pain receptors -axons that carry pain have little to no myelin so impulses travel slowly -thin myelinated axons travel faster and convey sharp early pain; signals the onset of a stimulus that tells its precise location which causes immediate withdrawal from the damaging stimulus -unmyelinated axons carry duller pain, late pain, such as postsurgical pain

synesthesia

experience people have when one stimulation of one sense evokes a perception of that sense(smell) and another one (vision) -1 in every 500 people -"the taste of beef is dark blue" -taste can be visualized -"sees" spoken language or words

semicircular canals

filled with a jellylike substance and lined with hair cells -acceleration of any angle of the head causes the substance to push against hair cells -this is turn causes action potentials from the vesticular system to travel via part of the eight cranial nerve to the brainstem and cerebellum

tinnitus

frequent or constant ringing in the ears

the outer ear

include the pinna -structure of the flesh and cartilage attached to the side of the ear -helps us locate the source of sound by altering reflections of sound waves

dermatome

when each spinal nerve innervates to a limited area of the body

the refractory period

when the refractory period reaches exceeds 100 Hz its becomes harder for a neuron to continue firing in synchrony with the sound wave -at higher frequencies it might fire every third, four or later so its action potentials are phase locked into the peaks of other sound waves -highest frequency sound vibrate hair cells near the base and lower frequency sounds vibrate hair cells farther along the membrane near the apex of the cochlea

sound localization

you are walling alone and want to know where a sound came from that you heard -can be done by comparing sound shadow: for high frequency sounds with a wavelength shorter than the width of the head, the head creates a sound shadow making the sound louder fro teh closer ear , difference in time of arrival at the two ears: a sound coming from directly in front of you reaches both ears at once and a sound coming from the side reaches the closer ear first , and phase difference between ears: every sound has two consecutive peaks 360 degrees apart

vesticular sensation

you can read while you jiggle your head up and down but cant read when what you are reading is shaken -this is because when you move your head you vesticular organ monitors positions and movements and compensates movement of your eyes (when your head moves right, your eyes move right -when the paper is moved, your vesticular organ cannot keep your eyes on target

mechanical senses

-vesticular sensation -touch -pain -body sensation

cannabinoids

(related to marijuana) block certain kinds of pain by minaly unlike opiates acting like a periphery of the body rather than the CNS

pheromones

(sex attractant) that is released by an animal to affect eh behavior of others of the same species

odors in men vs women

-women detect odors more easily and ready than men because the brain responses to odor are stronger -young adult women, girls before puberty, and women after menopause are more sensitive to odor probably because of the influence of hormones

damage to the primary auditory cortex

-hear simple sounds well unless the damage extends to subcortical areas -inability to recognize combinations or sequences of sounds, like music or speech

damage to the somatosensory cortex

-impairment and body perceptions depending on the location affected -ex pt with alzheimers disease could not point to where her elbows were and pointed somewhere around the wrist suggesting they were there

primary auditory cortex

-located in superior temporal cortex destination for more info from the auditory system each hemisphere receives most of its info from the opposite ear -organization of the auditory cortex parallels that of the visual cortex, the auditory system has a "what" pathway sensitive to patterns of sound in the anterior temporal cortex and "where" pathway in sensitive to sound location in the posterior temporal cortex and parietal cortex -auditory info crosses over from the superior olive and inferior collicus so that each hemisphere receives its major input from the opposite ear -each cell in the auditory cortex responds best to one tone; cells preferring a given tone in the auditory cluster together forming a map of sounds referred to as the tonotopic map SO the cortical area with the greatest response indicate what sounds are heard -

auditory cortex

-located in temporal lobe -auditory info passes through several subcorticol structures with an important crossover in the midbrain that enables each hemisphere of the forebrain to get its major auditory input from the opposite

VNO (vomeronasal organ)

-located near the olfactory receptors that are sensitive to only pheromones -each VNO receptors responds to just one pheromone and does not adapt after exposure -in humans, the VNO is tiny and has no receptors (olfactory cells take the place of VNO); part of the human olfactory system mucosa contains receptors that resemble other species of pheromone receptors so humans unconsciously respond to some pheromones through receptors in the olfactory mucosa -pheromones play a role in human sexual behavior -pheromones synchronize menstrual cycles of women who spend lots of time together and also enhance the regularity of the menstrual cycle of a woman who is in an intimate relationship with a man

types of touch receptors

-pacinian corpuscle type of touch receptor that detects sudden displacement or high-frequency vibrations on the skin -onion like outer craters that resist gradual or constant pressure -sudden or vibrating stimulus bends the membrane and increases the flow of sodium ions triggers and action potential -merkel disks: receptors that respond to light touch (women have smaller fingers so higher density that leads to more sensitive touch -the info from touch receptors in the head enter through the central nervous system through the cranial nerves

taste coding on the brain

-perception of taste depends on pattern of response across taste fibers (across-fiber pattern) -taste from the antieror two-thirds of the tongue travels to the chorda tympani, a branch of the VII(facial) cranial nerve -info from the posterior one-third part of the tongue and tongue is carried to the brain along the X (vagus) and IX (glossopharyngeal) cranial nerves -the facial, vagus, and glossopharyngeal nerves project to the nucleus of the tractus sollitarius in the medulla -the tractus sollitarius sends into to the pons, amygdala thalamus, two areas of the cerebral cortex (insula and primary somatosensory cortex)

somatosensory system

-sensation of the body and its movements including discriminative touch, deep pressure, cold, warmth, pain, tickle, itch, and the position and movement of joints -the cortex receives info from the contraleteral side of the body mostly

olfaction

-sense of smell -detection and recognition of smells that come in contact with the membrane of the inside of the nose -critical for finding food and avoiding danger in most animals

pitch perception theory

1) place theory: each area along the basilar membrane is tuned to a specific frequency and vibrates whenever that frequency is present -each frequency activates hair cells at only one place along the basilar membrane and the brain distinguishes frequencies by what neurons are activated -towards the beginning of the cochlea is higher pitches, towards the end is lower pitches -can explain high frequency sounds 2) frequency theory: we perceive certain pitches when the basilar membrane vibrates in synchrony with a sound causing axons of the auditory nerve to produce the same action potentials at the same frequency -if there is a sound that is 50 Hz, it would cause 50 actions potentials 3) current theories: low frequency sounds the best explained by the frequency theory and high frequency sounds best explained by the place theory

sweetness, bitterness and umani receptors operate by?

activating a G protein that releases a second messenger in the cell when a molecule binds to a receptor

middle ear

includes the tympanic membrane (eardrum) -vibrates at the same frequency as sound waves which strike it -attached to three tiny bones: maileus(hammer), incus(anvil), and stapes(stirrup) -receives vibrations which in turn vibrates the malleus and then incus and then stapes which

taste sensititivty

individual responses and differences to taste -also genetic factors and hormones can play a role -controlled by a single dominant gene -phenythlocarbomide used in research to test taste sensitivity

info from receptors

info from receptors below the head enter the spinal cord and passes toward the brain through the 31 spinal nerves including 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, and 5 lumbar nerves and 1 coccygeal nerve -each spinal nerve has a sensory component and a motor component called innervation and connects to the limited areas of the body -sent to the spinal cord then to the thalamus before traveling to the somasosensory cortex in the parietal lobe -travel in well defined pathways; touch is different from pain pathway

amplitude

intensity of a sound wave -loudness is the perception of intensity but not always related to loudness -faster speaking sounds could sound louder even though it has the same amplitude

humans localize

low frequency sound by phase difference high frequency found by loudness difference-sound shadow difference in time between the two is most useful for localizing sounds with sudden onset

hearing loss

most hearing impaired people respond slightly to loud noises -two types: conductive or middle ear deafness or nerve deafness or inner ear deafness -conductive occurs if bones of the middle ear fail to transmit sound waves to the cochlea; also caused by disease, infections, and tumerous bone growth BUT can be corrected by surgery -nerve or inner-ear deafness occurs from damage to the cochlea, hair cells, or auditory nerve : people hear only certain frequencies; can be inhertited or caused by prenatal problems or early childhood disorders ; can produce tinnitus; if the brain doesn't get the normal input

olfactory cells (smell receptors)

neurons that line the olfactory epithelium and are responsible for smell -produces rapid adaptation because continued stimulation of an olfactory receptor (more rapid than sight or hearing) -axons of the olfactory cells carry info to the olfactory bulbs; the olfactory bulb (bundle of nerves) sends its info to other forebrain areas and activates the prefrontal cortex - olfactory receptors are sensitive to related chemicals and unresponsive to others -made up of proteins that respond to chemicals outside the cell causing changes into a G-protein inside the cell; the G-protein chemical activates that lead in an action potential -the most strongly excited receptor inhibits the activity of the other ones (later inhibition) -given chemical produce responses in one or two kinds of receptors but inhibits the response or others in the process -the response of one receptor is good for identifying the nature of the molecule and the response enables more precise locations-possible only because of the large amount of olfactory receptors

how messages from smells get to the brain

olfactory receptors olfactory bulb cortex -axons from the olfactory receptors carry info form the specific chemical to the olfactory bulb (each odorous chemical excites only a limited part of the olfactory bulb which determines which smell sensation of which area of the olfactory bulb is excited -the olfactory bulb send its sensation to many parts of the cortex (connections precise and sensitive to only certain chemicals -organization of the olfactory cortex is almost identical to one another -olfactory receptors survive for just over a month and then are replaced by new cells that have the same odor sensitivity as the old one

taste buds

receptors on the tongue -have excitable membranes that release neurotransmitters to excite neighboring neurons -located in papillae (structures on the surface of the tongue); can have up to 10 or more taste buds and each taste bud has about 50 receptors -mostly located along the outside edge of tongue in humans

endorphins

release morphine like substances that attach to the same brain receptor as morphine -certain pains activate neurons that release endorphines in the gray are of the brain -block the release of substance P in the spinal cord and brainstem -block dull pain not sharp pain

gate theory

spinal cord neurons that receive messages from pain receptors also receive input from touch receptors and from axons descending from the brain -these areas that provide input can close the gates and decrease pain perception -by ronals melzack and patrick wall 1965 -ex: if you crack your skin a natural reaction is to rub the site of injury because it alleviates the pain

kinds of taste receptors

sweet sour salty bitter MSG( monosodium glutamate) -can adapt: after tasting a sour thing for two hours, the next thing wont be as sour -cross adapt: reduced response to one taste because of another

vesticular sense

system that detects the position and the movement of the head and compensates the movements of the eyes to maintain balance

pitch perfect

the ability to hear a note and identify it accurately -genetic predisposition or extensive music training -more common among people who speak tonal foreign languages such as Vietnamese

volley principle

the auditory nerve as a whole produces volleys of impulses for sounds up to about 4,000 per second even though no axon reaches that frequency -imporatant for pitch perfect below 4000 Hz although it is unclear how the brain uses this info

what is a sensory organ that senses sound waves?

the ear

what is a vesticular organ?

the ear which is adjacent to the cochlea and consists of two otolith organs: saccule and utricle; and it consists of three semicircular canals -calcium carbonate particles (otolith organs) lie next to the hair cellsin and excite them by shearing action when the head tilts in different directions which detects motion

amusia

tone deafness -impaired at detecting small changes in frequency -associated with thicker than average auditory cortex in the right hemisphere but fewer than average connections from the auditory to the frontal cortex

somatosensory pathway

touch path has different pathways conveying deep touch and light touch; same with pain -nervous system codes differences between these sensations in terms of which cells are active -thalamus sends impulses to different areas of the somatosensory cortex located in the parietal lobe -different sub areas of the somatosensory cortex repsond to different areas of the body

somatosensory receptors

touch-like and others responding to deep stimulation, joint movement or muscle movements -simple bare neuron ending -modified dendrite -elaborated neuron ending -neuron ending surrounded by non-neural cells that modify its function

itch

two types of itch: 1) when you ahve mild tissue damage such as skin healing after a cut, your skin releases histamine that dilate blood vessels and produce itching sensation 2) contact with certain plants produce itch -both show tactile sensations -activates a distinctive pathway that tends to be slower than other tactile sensations -impulses travel slowly -itch activates neurons in the spinal cord that produces a chemical called gastrin-releasing peptide