sensory physiology Flashcards
what is modality and quality for sensory system
what is being sensed
examples of Modality and quality
Vision Audition Balance Somatosensation Taste Olfaction Visceral
what are the submodalities of somatosensation
Pressure
Pain
Temp
what are the submodalities of taste
Sweet sour bitter salty Umami
what is the intensity of a sensation
how much
what is the lcoation of a sensation
where
what is the duration of a sensation
When
are all stimulus the same importance for each sesnory system
No
where do unique expereinces associated with a particular modality begin
at the receptor
what is the initial interaction of a stimulus with a receptor
transduction
what is transduction
transformation of a physical energy into a neural signal
the type of energy that a given receptor type is most sensitive to
adequate stimulus
the stimulation site that elicit neural response
Receptive field
types of thresholds
neural threshold
Perceptual threshold
neural threshold
the amount needed to depolarizae a neuron
preceptual threshold
absolute, difference
- how much it takes for one to notice
law of specific nerve energyeis
Central connection determine modality
i.e. stimulation of optic nerve bypassing receptors mean light
relates physical properiteis of stimulus to sensation
Psychophyscs
what types of sesnations have sensory receptors on the primary afferent neuron
Somatosensory (mechanoreceptors, thermoreceeptors, chemoreceptors, nociceptors)
Olfaction (chemoreceptors)
what types of sensations have sensory receptors on a recetpor cell that comunicates with the primary afferent neuron
Vision (photoreceptors)
Audition (mechanoreceptors)
Balance (mechanoreceptors)
Taste (Chemoreceptors)
what is a physical (direct) interaction of a stimulus
what interaction with membrane preotein opens ion channels
what senations do physical (direct) interaction
somatosensory
Vestibuluar
Auditory
taste
what is a molecular interaction with a stiulus
interactions with a membran protein (G-protein)
what sensations do molecular interaction
vision
taste
olfaction
how does direction transduction occure in the taste system
- Na+ enters through ENaCs(epithelial Na+ channels): depolarization of cell
- Action potential leads to Ca++ entry
- Release of ATP as neurotransmitter (not stored in vesicles)
what mechanoreceptors are used in direct transduction pathways
Piezo1 and piezo 2
what are piezo1 and piezo2
A unique family of large + transmembrane segments for direct transduction
key evidence of piezo 1 and piezo2
Dorsal Root Ganglion cell
Response to pressure
Knockouts show reduced response
what is TRP receptors
A direct transduction pathway of 31 types with 8 families
full name for TRP recptors
TRansient Receptor Potential receptors
discovery of TRP receptors
Family of ion channels first found in Drosophila then mammalian cells
what makes up TRP receptors
6 transmembrane domains with channel between 5 and 6
actions of TRP receptros
cation ion channels that can pass Ca++
activation of TRP receptors
large variety of activating mechanisms
- intracellular Ca++
- temp
- chem
- sound
- light
- pH
- osmolarity
- mechanical can open
- different TRP channels
what does the VAnilloid REceptor (TRPV1 or V1 respond to
capsaicin
heat ( >42 degrees C)
Protons
Stimulation of Vanilloid REceptor (TRPV1 or V1) leads to
influx of cations (Na+ and Ca++)
types of Indirect G-protein coupled receptors for olfaction
300-650 types
- Golf
- Gs
- 2 large families
types of Indirect receptors for vision
a dozen types
Rhodopsin (rods)
Photopsins (cones)
Types of Indirect receptors for taste
Gustductin
what submodality of taste does Molecular G-proteins work for
Taste
how does Molecular G-protein reception work for sweet taste
Sugars bind to REceptor coupled G-protein
Release of intracellular Ca++ activates TRPm5 channel (TRP)
Depolarization leads to AP and relase of Neurotransmitter ATP
general steps for coding for intensity
Increase in stimulus intensit
Increase in receptor potential
Increased number of APs
Correlation between neural response and Human perception
increased firing rate is directly related to perceptual response
what is THreshold
Not a precise value;
A statistical concept as a stimulus intensity dected on 50% of trials
what affects the threshold
not only a funtion of stimulus
- can be affected by psychological, neurological, or pharmacological factors
uses of threshold
Diagnostic tool
High odor threshold is predicitive of what
Alzheimer’s disease
how was it determined that high odor threshold predictive of alzheimer’s disease
Elderly patients tested in an odor threshold test
Cognitive test 1 yr after testing
PAtients with alzheimer’s had higher thresholds in the earlier olfaction threshold test
receptive field
what a receptor (or neuron) is sensitve to
what happens to location and intensity in a single neuron
Location and Intensity are confounded
roll of LAteral inhibition
Improves spatial localization( neurons lateral to a stimulus inhibit each other, so that only strong stimulus’s produce lots of AP
do indiviusal fibers respond to Odors
Noyt, specifically tuned, but are more broadly tuned
how do we get an infinite amount of odor qualities
Comparing activity across olfactory fibers
when are rapidly adapting singals important
for rapidly changing stimuli such as virbation or moving stimul
when is slowly adpating singalling important
for prolonged events (joint and muscle receptors that help maintain upright posture, provide signal for sustained pressure)
what does Presynaptic excitation or inhibition lead to
more or less Ca++ enry to modulate neurotransmitter release
the auditory pathway
- Hair cells (receptor cells) in cochlea (inner ear)
- Innervation by VIII nerve
- VIII nerve synapses in cochlear nuclei
- Ascending sensory pathway to cortex
- Efferent pathway from superior olivary nuclei
what is the Auditory Efferents
Efferents from the superior olive synapse on hair receptor cells
what is the synapse of the superior olive on hair receptors
is an inhibitory nicotinic receptor (Ca++ activated K+ Channels leading to hyperpolarization
roll of auditory efferents
functions to set gain of receptor neuron to respond to different kinds of auditory events
what is held in the olfactory cortex
frontal cortex
where is the auditory cortex
Temporal lobe
where is the somatosensory cortex
PArietal lobe
where is the taste cortex
Insular cortex
where is the visual cortex
Occipital lobe
what is the somatotopic map
the body representation of neurons
what is the Tonotopic map
auditory pitch representation
what is the Retinotopic map
Visual field representation
are sensory maps all the same
No dynapmic (plastic)
- experience
- Neurological injury
what happens to the cortical area if you over stimulate 3 and 2 digits
the 3rd and 2nd digit areas becomes larger (Central sprouting)
