6- General Principles of Sensory Systems Flashcards
What do vision receptors detect?
Light waves
What do audition receptors detect?
Sound waves
What is involved in vestibular senses?
Movement of liquid, gravity
What are the 2 chemical senses?
Olfactory (smell) and gustatory (taste)
What are the 2 body senses?
Touch and pain (somatosensory), movement (muscle, skin, joint)
Somatosensory neurons (6)
- Free nerve endings
- Merkel’s disk
- Free nerve ending associated with root of a hair
- Pacinian corpuscle
- Meissner’s corpuscle
- Ruffini corpuscle
What are somatosensory neurons sensitive to?
Physical distortion
How does sensory perception differ?
Between species
What does each sensory system have?
Specific receptors
What do secondary receptive fields include?
Overlapping primary receptive fields
What do primary sensory neurons converge upon?
1 secondary neuron
What are receptors classified on? (3 things)
Morphology, adaptation, receptive fields
Where is the most sensitive area in the body? (Two-point discrimination)
Fingertips
3 reasons why fingertips are the most sensitive area of the body
- High density of mechanoreceptors
- Receptors with small receptive fields
- More brain tissue devoted to fingertips
What are the 2 main processes in reception?
Transduction and transmission
What is neural coding?
Stimulus properties need to be coded by neurons
What are external signals transformed to in transduction?
Action potentials
What is rate coding?
Coding by frequency/firing rate
What is adaptation in rate coding?
Reduction of neural activity over time when stimulus is constantly presented
What is the system more interested in with rate coding?
More interested in changes than consistency
What is place coding?
Coding by location
What is labelled-line coding?
Coding to a specific sense
What is the problem with labelled-line coding?
Receptors aren’t specific enough to detect fine differences
What is population coding?
Coding by multiple receptors
What determines specific sensation?
Activation of many neurons together
What is firing rate limited by?
Refractory period
What is the pathway in transmission?
From neuron to cortex: receptor –> peripheral pathway –> thalamus –> primary sensory cortex –> secondary cortical areas
What is tonotopy?
A columnar organisation of cells with similar binaural interaction
What is somatopy?
Differences in acuity correspond to the differences in relative proportions of the secondary sensory cortex devoted to analysing information from these body regions
What does the bottom-up approach suggest?
Extraction of stimulus features from data without prior knowledge/memory/attention
What does the top-down approach suggest?
Influence from higher levels of nervous system to lower
