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99 Cards in this Set

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  • Back
What is the study of the relationship between a stimulus and the subjective experience of that stimulus?
In general, what are our receptors most sensitive to?
The most important stimuli
What is the intensity of a stimulus needed to cause detection 50% of the time?
Absolute threshold
What is sensitivity of a sensory system to be able to tell the difference between two stimuli? What does it depened on?
1. Difference threshold
2. The size of the two stimuli
What law states the that "just noticble difference" is constant for each sensory system?
Weber's Law
What are the four basic attributes to a stimulus?
1. Modality
2. Intensity
3. Timing/Duration
4. Location
What attribute of a stimulus defines a general class?
What determines modality?
1. Type of energy transmitted
2. Specialized receptors present
What are the eight modalities listed for us to remember?
1. Touch
2. Taste
3. Smell
4. Vision
5. Hearing
6. Proprioreception
7. Pain
8. Balance
Why do we have submodalities?
Because within each modality, there are different receptors that are only sensitive to particular stimuli
What does Muller's Law describe?
The relationship between a modality and the specific afferent fibers that carry that modality.
How does your brain know what type of input it is receiving?
The source or origin tells the brain whether the signal is sight or sound (that is an example).
What aspect of a signal determines the stimuli's orginal intensity?
The frequency of the incoming signal
What is another term for the number of receptors activated by a stimulus?
Population code
What modality refers to when a stimuli begins and ends?
Duration or timing
What is the term that refers to the change in response to a constant stimulus over a peroid of time?
Is the speed of adaptation constant?
No it can be fast or slow depending on the receptor
What is the area in the periphery where application of an adequate stimulus will cause the cell to respond?
Receptive field
What determines spatial resolution?
The size of the receptive field and the receptor density within the receptive field
Describe the receptive field and receptor density of the most sensitive areas of the body?
1. Small receptive field
2. Large receptor density
What is the minimum distance between two stimuli for you to perceive them as two stimuli?
2 Pt descrimination
What areas have the smallest 2 Pt descrimination?
Face and hands
What is an orderly arrangement of RFs so that adjacent points on the skin relate to specific locations in the brain?
Topographic map
How are the sizes of different areas of the map related to the number of receptors present in that body part?
The larger the number of receptors present in a body part, the larger the body part appears on the map.
What is the concept of variable magnification?
The fact that an area with a small RF could have a large representation on the map
What term refers to the changing of a physical stimulus into a neural signal?
When might a receptor create an action potential instead of a receptor signal?
When the signal created has to travel a long distance, an action potential will be created instead.
What is one reason that RFs get larger and more complex?
There is a lot of convergence of different signals that adds to the complexity of the system
What plays a role in sharpening the contrast in the somatosensory system?
Which type of connection is considered to hierarchial?
Serial connections
What type of processing do we typically use? Why?
1. Parallel
2. Most stimuli are larger than one RF and different receptors are sensitive to different aspects of a given stimulus
What two NTs were give as an example of having divergent processes?
Dopamine and Seratonin
Is convergence or divergence common in the brain?
What type of representation is present in the cortex in relation to hearing?
It is bilaterally represented
What are the four perceptual modalities?
1. Tactile - fine touch
2. Proprioreception
3. Thermal
4. Pain
What type of receptor is used for touch?
What are mechanoreceptors sensitive to?
Deformation or stretching of the skin
How do mechanoreceptors physically propagate the stimulus?
By sending action or receptor potentials
Name the three encapsulated receptors and what they are sensitive to.
1. Pacinian corpuscle - vibration
2. Meissner's corpuscle - simple touch
3. Ruffini ending - pressure
Is a Merkel ending encapsulated or not? What is it senstive to?
1. No it is not.
2. Touch
Which two receptors are superficial?
1. Meissner's corpuscle
2. Merkel
Which two receptors are deeper in the skin?
1. Pacinian corpuscle
2. Ruffini ending
Which two receptors rapidly adapt?
1. Meissner's corpuscle
2. Pacinian corpuscle
(Both corpuscle)
Which two receptors slowly adapt?
1. Merkel
2. Ruffini ending
What are two broad categories for receptors of proprioreception?
1. Encapsulated muscle spindles
2. Golgi tendon organs
What type of muscle do you find stretch receptors in?
Striated muscle
What makes up a stretch receptor?
A few intrafusal muscle fibers covered by a central capsule
Are muscle spindles in series or in parallel?
Are golgi tendon bodies in series or in parallel?
What stretches a muscle spindle?
The lengthening of the muscle it is in
What type of neurons control muscle spindles?
Gamma neurons
What are the two types of nerve endings in a muscle spindle? What are they sensitive to?
1. Primary or annulospiral - onest of stretch
2. Secondary or flower splay - maintained stretch
How are golgi tendon bodies formed?
Afferent fibers enter a capsule and become intertwined in a tendon
What does a golgi tendon body monitor?
Tension associated with contraction of the muscle
Which has a faster pathway, pain or discrimintive touch?
Discrimintive touch
What are the two properties to describe axons?
1. Thickness
2. Conduction velocity
What type of neurons carry afferent information?
Pseudounipolar neurons
Where do you find the cell bodies for pseudounipolar neurons in the periphery?
Dorsal root ganglion
What are the skin surfaces innervated by a particular afferent nerve called?
What are three functions of central afferent branches?
1. Reflexes
2. Projecting to the ipsilateral cerebellum
3. Main two ascending pathways
Where do the dorsal columns dessucate?
The caudal medulla
What could account for a loss in just proprioreception or just touch?
The fact that proprioreception and touch are segregated in the dorsal column system could account for this.
The anterolateral system is another name for what system?
The spinothalamic tract
What is a new term for the ventroposterior complex?
Somatosensory thalamus
Why is it hard to define the functional units of the cortex?
The are very homogenous
What are five of information used to define an area of the cortex?
1. Architecture - histology
2. Map of the outside world
3. Neural responses
4. Unique connections with other parts of the cortex
5. Functional contributions (fMRI)
In a typical somatosensory map, where are the areas for the face? The lower extermities?
1. Lateral
2. Medial
What are the four areas (Brodman) for the primary sensory cortex?
1, 2, 3a, 3b
According to current research, how many somatosensory areas does the human brain have?
Are the four areas of the primary sensory cortex in parallel or series?
Where can the map SII be found?
In the operculum or insular cortex
What Brodman areas define the sensory association cortex?
Areas 5 and 7
In the original studies of SI, which areas were the only ones mapped and why?
1. 3b and 1
2. Easiest to map because they are light touch (cutanteous)
Which areas of SI are the easiest to map and why?
1. 3b and 1
2. They represent cutaneous light touch
Which areas of SI have congruent borders and are mirror images of each other?
1 and 3b
Are the gentials or feet more medial in the somatosensory map?
The feet are more medial
What is the modality and input of Area 3b?
Mainly cutaneous input from the VP with a little pain and temperature
What is the modality and input of Area 1?
Cutaneous input from VP nucleus with minor pain and temperature
What is the modality and input of Area 2 and 3a?
Deeper proproreceptive input
Is SII bilaterally or unilaterally inputed?
What type of function is SII used for?
Intermanual transfer (not the only thing)
More primitive mammals have how many somatosenory areas?
In a primitive mammal, their SI is comparable to what area in humans?
The cortex has what sort of organization?
What is a feature of all the neurons within a given column in the cortex?
They all have the same RF and respond to the same modality.
Most connections in the cortex go in which direction?
Up and down, might account for the columnar arrangement of the cortex.
Do cortical areas receive input from one layers of the the thalamus or multiple layers?
Nuclei in the thalamus projetc to (one/many) cortical targets.
Area 3b projects to...
Areas 1 and 2
Area 3a projects to...
Areas 1 and 2
Areas 3a and 2 project to...
Other parietal areas such as 5
In general SI will project to...
In general SII will project to...
Other insular areas
In general "other insular areas" will project to...
Parahippocampal gyrus
What is the binding problem?
Since the brain uses parallel processing, no one area gets all the somatosensory input. How does the brain understand what is going on with all this different input going to so many different places? It is not known.
What is the tradiational and new view of somatosensory plasticity?
1. Traditional - plasticity only occurs in yound brains
2. New view - plasticity can occur in mature brains
With the new view of plasticity, what are the two phases of change?
1. Immediate - very small changes
2. Delayed - larger changes over time
Besides deaffarentation, what is another way to increase the somatosensory map?
Increased stimulation to that area
In plasticity, are the changes limited to changes in the cortex?
No, the extent of the changes were to great so changes must have happened in other areas as well.