Topic 8.2 Flashcards
4 basic properties of sensory stimulus
Modality
Intensity
Duration
Location
10 major modalities
- Vision
- hearing
- Smell
- Taste
- Touch
- Flutter-vibration
- Temperature
- Proprioception
- Linear and rotational acceleration
- Nociception
What is threshold
The smallest level of a stimulus that can be detected 50% of the time
3 ways of encoding stimulus
- AP frequency
- Population of receptors activated
- Types of receptors activated
Steven’s power law
Sensation magnitude = k x I^n
K : proportionality constance (dpdt on unit of intensity)
n : power exponent (depends on modality)
Weber Fechner law
k = dI/I
K = constant, depends on modality dI = minimal change in the intensity required to produce just noticeable change I = intensity of stimulus where change occurs
What is 2 point discrimination
The ability to recognize that 2 nearby objects touching the skin are 2 distinct points
Information coding by the receptor (5)
- Anatomy of the receptor (cell type)
- Location of the cell body of order neuron
- Vertical and horizontal organization of fibers
- Topology : dermatome / tonotopy
- Receptive field
What is a dermatome
An area of ski that is supplied by afferent nerve fibers from a single dorsal root of spinal nerve
Bipolar neurons location (4)
- olfactory
- retinal
- auditory
- vestibular
What is a receptive field
Are that can trigger neuronal responses when stimulated, that the neuron can receive information from
A alpha diameter and velocity of conduction
12-20micro meter
72-120 ms
A beta fibre diameter and conduction velocity
6-12 micrometer
36-72 ms
A delta diameter and conduction speed
1-6 micro meter
4-36 ms
C fiber diameter and velocity
- 2-1.5 micrometer
0. 4-2 ms
Receptors in hairy skin (2)
- Hair follicle (free nerve ending)
- Ruffini’s corpuscle
Receptors in non hairy skin (3)
- Merkel’s disc
- Meissner corpuscle
- Pacinian corpuscle
Hair follicule adaptation and role
- Rapid adaptation
- Velocity, direction of movement
Ruffini corpuscle adaptation and role
- slow adaptation
- stretch, joint rotation
Meissner corpuscle adaptation and role
- rapid adaptation
- touch, point discrimination, fluttering
Merkel disc adaptation and role
- slow adaptation
- pressure, edges, points
Pacinian corpuscle adaptation and role
- rapid adaptation
- sense vibration, tapping
Projection somatosensory pathways
Brodmann area 3, 1, 2 (primary somatosensory cortex)
Type of interneurons in VPL and VPM
GABAergic inhibitory interneurons
Where is info from the 4 areas of S1 sent?
To are 5 and S2
3 ways for lateral inhibition
1 - feedback inhibition
2 - feed forward inhibition
3 - descending inhibition
