Midterm 2 Flashcards
What are the 3 parts of the somatosensory system?
cutaneous senses, proprioception, kinesthesis
What are cutaneous sensess?
perception of touch and pain from stimulation of skin
What is proprioception?
ability to sense position of the body and limbs
What is kinesthesis?
ability to sense the movement of body and limbs
What is the difference between proprioception and kinesthesis?
position VS movement
What does the cutaneous system consist of?
skin
What is the heaviest organ in the body?
skin
What makes up the epidermis?
dead skin cells
Where are mechanoceptors locatd in the skin?
dermis
What is the equivalent of mechanoceptors in auditory and visual systems?
hair cells and photoreceptors
What mechanoreceptors are located close to the surface of skin?
merkel and meissners
(2 M)
What are slow adapting receptors? Examples?
fire continuously whilst stimulus is present
merkel and ruffini
What are rapidly adapting receptors? Examples?
fire only when stimulus is first applied and when removed
meissners and pacinnian
What are merkel receptors responsible for?
sensing fine details and shape
What are meissner’s corpuscles responsible for?
controlling hand grip and motion across skin
What fibers do merkel receptors connect to?
slow adapting fibers
SA1
What fibers do meissner’s corpuscles conenct to?
rapidly adapting fibers
RA1
How do merkel receptors detect shape?
different firing rates for different locations on skin
react stronger to smaller ball because stronger curvature
What fibers do ruffini endings connect to?
SA2
What are ruffini endings responsible for?
stretch perception
What are pacinian corpuscles responsible for?
vibration and fine texture
What fibers do pacinian corpuscles connect to?
RA2 or PC
Which of the 2 major pathwaays in spine consist of larger fibers?
medial lemnisical
spinothalamic is smaller fibers
What info is carried in medial lemniscal pathway?
proprioceptive and touch information
large fibers
What info is carried in the spinothalamic pathway?
temperature and pain information
small fibers
Do the 2 major pathways in spinal cord cross over? Where do they synapse?
yes
VL nucleus of thalamus
What brain structures are associated with the cutaneous system?
S1, S2, anterior cingulate cortex (ACC), insula
What can cause plasticity and change homunculus?
adding/removing stimulus to certain body part can lead to plasticity
What is tactile acuity?
ability to feel details, 2 point discrimination
What are 3 ways you can measure tactile acuity?
2 point threshold, grading acuity, raised pattern identification
What is grading acuity?
placing grooved stimulus on skin and asking orientation
Where are merkel receptors densely packed?
fingertips
When looking at response of merkel vs pacinian receptors to grading what do you see?
merkel has spikes that correspond to gratings, more finely tuned
pacinian is less refined
Are low or high values good for tactile acuity scores?
low, cause thats the space you can discriminate
What allows pacinian corpuscles to detect vibration?
the strucutre, big corpuslce tha surrounds fiber
What does the corpuslce consist of?
layers, fluid between layers
Perception of texture relies of what 2 cues?
spatial (size/shape/distribution) and temporal (rate of vibration as skin moves across teexture) cues
What does the duplex theory of texture perception say?
2 receptors might be responsible
They did an adaption experiemtn using 10 Hz for meissners and 250 Hz for pacinian, what did they find?
only 250Hz adaption affected perception of fine texture
How is texture represented in the brain?
pattern of response across many neurons
distributed code
Lieber and Bensmaia studied textures and found?
differnt textures cause different fiirng patterns, different neurons responded different to same texture
Humans use _______ touch to interact with the environment?
active
Haptic perception is?
active exploration of 3D objects with hand
What 3 systems does haptic perception use?
sensory, motor, and cognititve
How fast can peopel detect things haptically?
1-2 seconds
Hairy skin contains an additional nerve fiber called?
CT afferents
Why are CT afferent so slow?
unmyelinated
What do CT afferents respond to?
light touch, beleived to signal social touch
Where do CT afferents go?
insula
How do SA2 and CT fibers react to stroking different?
SA2 inccreases response as speed increases
CT peaks at 3-10cm velocity and then decreases
What influences how we react to social touch?
top down processing
What is nociceptive pain?
signals impendign damge to skin
heat, chemicals, sever pressure, cold
What is inflammatory pain?
caused by damage to tissues/joints or by tumor
What is neuropathic pain?
damage to CNS
What are problems with direct pathway model of pain/
pain can be impacted by mental state, can occur without stimuli to skin, can be affected by atteention
The gate in gate theory of pain consists of?
susbtantia gelatinosa cells in spinal cord
Input to gate from gate theory of pain comes from/
L fibers (tactile), S fibers (nociceptors), central control (cognititve factors)
Pain does not occur when gate is closed by?
stimulation in SG- from central control or L fibers into T cell
Pain does occur from stimulation from?
S fibers into SG+ into T cell
What is nocebo?
neagtive placebo
effects result from negative expectations
What evidence shows that endorphins relieve pain?
naloxone blocks receptor sites causing more pain, naloxone also decreases effect of placebos, poeple who release more endorphins have higher pain toelrance
Does watching a loved one receive pain cause activity in brain?
yes in areas related to pain response
but none in somatosensory
What does social exclusion activate?
dACC
physical social pain hypothesis
What are the 2 chemical senses?
taste and smell
receptors interact with molecules in environment
What are the “gatekeepers” of the body? Why?
the chemical senses
warn us about if things are safe to eat or harmful
Olfaction and taste have ________ neurogenesis?
constant
How often do olfactory receptors undergo neurogensis?
5-7 weeks
How often do taste receptors undergo neurogenesis?
1-2 weeks
Why do the chemical senses gp under neurogenesis so much?
cause they are constantly exposed to the environment
What are the 5 basic taste qualities?
salty, sour, sweet, bitter, umami
What is umami described as?
meaty, brothy, or savoury
What is umami assocaited with?
monosodium glutamte (MSG)
Sweetness is often associated with substances that?
have nutritive value
Bitter is often associated with substances that?
are potentially harmful
trigger automatic rejection responses
Saltiness indicates that?
sodium is present
How do sweet compounds effect gastrointestive system?
cause anticipatory metabolic responses to prepare body to eat
Is there a perfect connection between tastes and function of substances?
no, but there is a connection
What are the four categories of papillae?
filiform, fungiform, foliate, circumvallate
What are filiform? Where are they located??
papillae that are shaped like cones
entire tongue
What are fungiform? Where are they located?
papillae shaped like mushrooms
found on sides and tip on tongue
What are foliate? Where are they located?
papillae shaped like a series of folds
on back and sides of tongue
What are circumvallate? Where are they located?
papillae shaped like flat mounds in a trench
on back of tongue
Where are taste buds located?
in all papillae except filiform
Each taste buds has how many taste cells?
50-100
What do taste cells look like?
tips that extend into the taste pore
When does transduction occur in taste?
when chemicals contact the receptor sites on the tips of taste cells
How many taste buds on tongue?
10,000
What are the four fibers that send signals from taste cells to brain?
chorda tympani nerve
glossopharyngeal nerve
vagus nerve
superficial petronasal nerve
What taste cells does the chorda tympani nerve receive signals from?
taste cells from front and sides
What taste cells does the glossopharyngeal nerve receive signals from?
taste cells from back of tongue
What taste cells does the vagus nerve receive signals from?
from mouth and throat
What taste cells does the superficial petronasal nerve receive signals from?
from soft palette
The pathways in the taste system make connections in?
the nucleus of the solitary tract of the spinal cord, then thalamus, then areas in frontal lobe
What areas in the frontal lobe do the taste pathways eventually reach?
insula, frontal operculum cortex, orbital frontal cortex
What is population coding?
info is represented by combined activity of a group of neurons
What is the evidence for population coding in taste system?
Erickson presented multiple taste stimuli to rats and found that the reaction to KCl and NH4Cl were similar and NaCl was different
they were then shocked when drinking KCl and avoided NH4Cl and not NaCl
What is the evidence for specificity coding in taste system?
Mueller used genetic cloning to try and make mice with a receptor for a substance they dont usually have one for (PTC).
It was successful
Also did diff study where they blocked salt receptros, decrease in response from receptors for salty but not in bitter/sour
What does amiloride do?
blocks flow of sodium to taste receptors when paplied to tongue
What type of coding is likely responsible for basic taste qualities? What about higher taste qualities?
specificity
population
People that can’t detect PTC are called?
non taster
if they can its taster
People that can detect PROP strongly are?
supertasters
What does macrosmatic mean?
keen sense of smell that is necessary to survival (food, sexual reproduction, etc)
most animals are this
What is a humans sense of smell like?
microsmatic
What does microsmatic mean?
less keen sense of smell that is not necessary for survival
humasn
What are pheromones?
chemicals released by members of species that cause reaction in other members of same species
Is there evidence that humans have pheromones?
yes
men rated shirts worn by women for 3 consective nights as nicer when they were ovulating
What do people with anomsia report?
social insecurity, fewer sexual relationships, lack of enjoymenet of food
What are 2 procedures used to detect threshold for odors?
yes/no procedures, forced choice
What does the yes/no procedure look like when testing smell?
given trials w/odors and some w/o, they answer yes/no if they smell it
What does the forced choice procedure look like when testing ssmell?
given 2 options, one w/smell one w/o, pick which one smells stronger
Rank the sense of smell from weakest to strongest, rats, dogs, humans?
humans -> rats -> dogs
Why are dogs more senstivie to smell than humans?
they have more receptors
receptors are equally senstivie between dogs and humans
Are detection thresholds the same for different compounds? (smell)?
no
What device is used to measure difference threshold in smell?
olfactometer
What is the difference threshold of smell?
approx 11%
What is the recognition threshold?
concentration needed to
determine quality of an odourant
How many odors can human tell apart?
humans can discriminate among 1 trillion odors but cant name them
if given names of substances before test we are really good, if not only 50%
How does covid damage smell?
covid molecules attach to enzyme ACE2 found in nose and other places, effects supporting cells in olfactory system not receptors
WHen does loss of smell in Alzheimers patients occur?
decades before memoy loss and other clinical symptoms
What is the difference in damage to olfactory system caused by covid and alzheimers?
AD causes more widespread damage to olfacotry system
olfactory bulb and other central structures are damaged
Out of visual/auditory/olfactory which system is most senstivie to neural dysfuntion?
olfactory
What is the puzzle of olfactory quality?
similar structures may cause diffeerent smells and different structures may cause same smell
not sure why
Where is the olfactory mucosa located?
top of nasal cavity
Where are olfactory receptors contained?
in olfactory receptor neurons (ORN)
in olfactory mucosa
What are glomeruli in olfactory system?
in olfactory bulb
axons from olfactory receptor neurons (ORNs) converge
How many types of olfactory receptors are there?
350
How does calcium imaging work?
conc. of Ca increases inside ORN when olfactory receptors responds
Ca is detected using chemical that makes it florescent
increase in calcium decreases fluresnce
What is the combinatorial code for odour? Evidence?
odourants are coded by patterns of activation of
olfactory receptors called recognition profiles.
Malnic proposed this from results of calcium imaging tests
2 techniques have been used to determine how the glomeruli respond to different odorants?
optical imaging
2DG tecgnique
How does the optical imaging method work?
cortical cells consume O2 when activated, red light is used to measure how much O2 in cells, less oxygen reflects less red light
areas that are activated refelct less
Is there evidence for a hard wired response to odours?
yes
rats not exposed to cats still show fear response when smelling one
female rabbits release phermones that cause nursing behaviour in baby raabbits
What is 2DG techniqur?
animals injected w/2DG which is radioactivate, also contains glucose
neural activation is meaasured by amount of radioactivity
Signals from olfactory bulb are sent to?
primary olfactory (piriform) cortex in temporal lobe and amygdala
then secondary olfactory (orbitofrontal) cortex in frontal lboe
What steps in the olfactory pathway sends info to amydaalaga?
olfactory bulb, piriform and orbitofrontal cortex
input and output
Will looking at activity in piriform cortex allow you to distinguish odors?
no, response is same
Researchers have drawn parallels between recnogizing odors and creaating memories T/F?
true
the co-activation of neurons forms links
between them, and these patterns are recognized or
learned
Flavour is?
combination of smell, taste, and other sensations
Odor stimuli from food in your mouth reaches olfactory mucosa through?
through retronasal route
Example of compound whose taste is not impacted by olfacttion?
MSG
Responses from taste and smell are first combined in?
orbito frontal cortex
Is flavour influenced by cognitive factors/
yes
people react more pleasently to more expensive wine
activity in OFC also changes
What is proust effect?
the ability of taste
and olfaction to unlock memories
How small of a time interval can humans distinguish between?
1/10th of a second
What is human’s time perception abilities useful for?
communication, coordinating movements to acheive goals, plan future events, remember past events
What phsyiological changes occur in a 24 hour cycle?
sleep wake, blood pressure, pulse, body temp
What is the difference in body temperature in 24 hour cycle?
more than degree celcius
Is there evidence that circadian rhythms are based on biology or environment?
Aschoff did expereiment where people were kept in bright room 24/7, naturallly adopted 25 hours rhythm
How long does it take for us to adjust to new time zone?
1 day per 0.5-1 hour offset
Do blind people have disrupted circadian rhythms? Why?
yes, 76 % have trouble falling asleep
cause lack of light
difficutlies are cyclical
What happened in rats when suprachaismatic nucleus was damaged?
caused random sleep schedule
SCN receives input from?
visual system, and pineal gland
What gland secretes melatonin?
pineal gland
What biological mechanisms have been proposed to measure short time intervals?
heart beats, breahting, metabolic activity, even walking
Why is 30ms imporntat?
smallest time difference we can reliably discriminate`
What are micropatterns?
small variations in a pattern that occur so quickly you cannot see them
The experiement with the clicking intervals suggests that info is chunked in?
150ms intervals
The length of our perceptual moment is between? This is determined by?
25-150 ms
short term biological clock
Can things that affect our physiological functioning affect our sense of time?
yes
How are internal time clocks in hyperactive children different?
their clocks are faster
makes physical time feel slower
What drugs make your internal clock go faster?
amphetamines, caffeine
How does fatigue affect the biological clock?
slows it
They did experiment where they dropped people to see if fear slows down biologica lclock, what did the date show?
no significant change
How is the basal ganglia related to time perception?
via dopamine production
modulates time perception
How do dopamine agonists affect passage of time?
speed up time perception
How is the cerebellum realted to time perception?
timing of motor tasks
How is the prefrontal cortex related to time perception?
expected duration, anticipation
What is the information storage size theory?
perceived time duration is based on the contents of one’s memory
robert ornstein
According to the information sotrage size theory what factors influence the amount of information that can be processed?
number, complexity, efficiency of storage and coding
According to information storage size theory increasing the number of events?
increased perceived duration
Filled time intervals are judge to be _______ than empty intervals?
longer
Are complex or simple melodies judged to be longer?
complex
In hindsight are empty or filled intervals judged to be longer?
filled
opposite of when its happening
Time perception depends on both?
biological and cognitive factors
What are 3 techniques that we use to measure perception in infants?
preferential looking technqiue, habituation technuque, visual evoked potential
What is the preferential looking technique?
infants have spontaneous looking preferences, when presented w/stimulus they measure what/how long babies look at stimulus
What is visual evoked potentials?
measured eletrical activity on surface of brain in response to visual surface
baby brain is close to surface (occipital)
What is spatial frequency?
the number of cycles tht fall in 1 degree of visual angle
How does visual acuity of babies change with age?
steady increase til about 8 months than it plateaus
Full adult acuity is acheived by infants by what age?
1 year
Why is humans visual acuity so low at birth?
visual cortex is not fully developed, shape/size of cones is not fiully developed
What is the difference between newborn cones and adult cones?
newborn aare wide and short, gaps in the lattice
adult are much longer and thinner, no gaps in lattice
Infants can only perceive contrast at _____ freuqnecies?
low
gets worse at the freuqnecies adults are best at
very bad even at low contrast
How does the habituation technqieu work?
infants look at new stimuli more, so they show infatn one thing over and over again to habituate them, then they change it, if infant can perceive the difference dishabituation will happen
Do infants categorize colours the same way adults do?
yes
When can infants start to binocularly fixate?
approx 3 months
What did the visual cliff expereiemtn show?
babies at 6 months would craw across deep side but 8 month olds would not
cause they learned depth perception
When placing 3 month olds on deep side of visual cliff experiemtn waht did they find?
heart rate would increase
difference betwen perceiving the depth and understanding the consequences
What age to infants start to use familiar size?
7 months
How old do babies start to identify faces?
8 weeks
Babies use the contrast of hairline to face as a cue? T/F
True
What is a thing that infants can perceive but adults cant? (faces)
non human primate faces
can tell apart lemurs even when adults who work with them cant
What helps infant with perception of object unity?
movement
experiemtn with rods moving, either 1 or 2
6 month olds show similar audibility curves to adults within _____?
10 - 15 decibels
Do infants recognize their mothers voice?
yes
When does speech perception in infants occur?
before the infant can produce speech
At birth what phonemes can infants distinguish between?
phonemes of all languages
phonemes comprehension becomes tuned to native language as they age
What is infant directed speech?
aka parentese
uses specific characterisitics to get babies attention and help them recognzie words
What are some characteristics of infant directed speech?
high pitch, larger range of pitches, slower, words are more separated, words are often repeated
What is the earliest sensory modality to adapt?
touch
emerges 8 weeks after gestation
What is touch felt by infants related to in adults?
social touch in CT afferents
Soft brush strokes to legs of infatns of 11-16 day old infants activates?
the posterior insula
Can infants perceive music?
yes they can perceive th beat
dont move rhytmically to music
What can infants not taste?
salty stimulus
What are the most highly developed senses at birht?
taste and olfaction
Perceptual disorders are due to?
cortical damage or disruption to cns
What is ageusia?
lack of taste
What does losing all your cone receptors cause?
achromatopsia
What causes colour blindness?
loss of 1 cone type
How does frequent exposure to loud noises impact hearing?
damage to outer hair cells, basilar membrane movement is reduced
What is congential analgesia?
people born without nociceptors
cant feel pain
How does leprosey affect your snesory systems?
lack of pain perception
What type of damage causes blindsight?
damage to the primary visual cortex only
What is blindisght?
patient reports being completely blind but are able to grab moving object and follow light with eyes
they are unaware they can do this
What is anton-babinski syndrome?
when people who are blind deny it
What is visual agnosia?
inability to recognize/draw/copy objects
What damage causes visual object agnosia?
damage to left occipital lobe in V2
damage is also often bilaterla
What 2 types of damage are often found in ppeople with prosopagnosia?
bilateral damage to inferior temporal lobe
unilateral damage to right posterior parietal lobe
What is akinetopsia?
inability to see movmenet, trouble determining if obejct is stationary or moving
What damage can cause akinetopsia?
damage to MT or parietal lobe
Is neglect syndrome limited to a signal sensory modality?
can be restricted to vision but often affects other sensory systems
What is hemifield neglect usually caused by?
right posterior parietal lobe damage
What damage cauuses dorsal simulanagnosia? Ventral?
bilateral damage to parietal and occipital areas
bilatearl damage to temporal and occipital areas
What is the difference between dorsal and ventral simulatagnosia?
dorsal is inability to see 2 things at same time
ventral is inability to identify 2 things at same time
What is global deficit? (neglect)
neglect of visual, auditory, & somatosensory stimulation on the side of the body and/or
space opposite to the lesion
What is dressing apraxia?
type of neglect
only dress half of the body
What is paralexia?
type of neglect
only read half of a word
What is paragraphia?
type of neglect
only write half of a word
What is anosognosia?
type of neglect
denial of illness/symptoms
What damage causes astereognosis?
damage to primary somatosensory cortex
aka tactile aphasia
What is asomatognosia?
loss of knowledge/sense of one’s own body
What is somatoparaphrenia?
denial of ownership of limb/hand
What is misoplegia?
extreme form of somatoparaphrenia
hate/revulsion toward body part
WHat % of amputees experience phantom limb?
95%
What is ideomotor apraxia?
unable to copy movements or make gestures
What daamage causes ideomotor apraxia?
left posterior parietal area
What is constructional apraxia?
unable to perform activities involving aseembling, building, drawing
What damage causes constructional apraxia?
injury to either parietal lobe
Damage to the primary audtiory cortex can cause?
deficits in:
perception of brief temporal sequences of sound
perceiving rapid speech
What are the 2 categories of audtiory agnosias?
semantic associative and discrimintive
What is semantic associative agnosia?
loss of meaning from spoekn words
can read/use ASL
What damage causes semantic associative agnosia?
left hemisphere, wernickes area
What is discriminitive agnosia?
inability to distinguish between different sounds
unable to determine their cause
What hemisphere is damage in discriminative agnosia?
right
What is phonagnosia?
inability to reocgnize or discriminate between voices
What is the difference between anosmia and hyposmia?
lack of smell VS decreased ability of smell
What is dysosmia?
distorted identification of smell
What is phantosmia?
perception of smell w/o odor present
