Introduction to Perception Flashcards
What are some examples of sensory Modalities?
- Somatic Sensation (Discriminative Touch, Proprioception, Pain, Temperature)
- Vision
- Hearing
- Balance
- Olfactory
- Gustatory
What is a sub modality? Give an example.
Differences in the quality of the sensation being perceived.
Vision: color, distance, movement
What is sensation?
Awareness due to stimulation of a sense organ
What are the components of a sensory system?
- Receptors (Sense Organs)
- Pathways
- Target Areas
What are the common features of the sensory modalities?
- A physical stimulus
- Transformation of the stimulus into neuron signals.
- A response to the signals in the form of a perception or conscious experience of sensation.
What is perception?
An internal construction of the external world according to CNS constraints.
Ex. Taste, sound, smell, color tones
What does a neural code do?
Describes the relationship between the activity in a specified neural population and its functional consequences.
What are the 4 attributes of stimuli?
- Modality
- Location
- Intensity
- Timing/Duration
What is a modality, give an example, and how do we code for it?
- Defines a general class of stimulus (ex. touch)
- We code for it by the stimulus energy and the RECEPTORS specialized to sense that energy.
What is the labeled line code?
The coding mechanism for stimulus modality and is based on the specificity of response in receptors.
What are sensory receptors?
- First cell in each sensory pathway
- specialized to transform stimulus energy into electrical energy (signals)
How are sensory receptors classified?
- based on the type of stimulus energy that they are most sensitive to
What are the properties of the modality?
- Each receptor responds to a narrow range of stimulus energy
- They transduce stimulus energy into electrical signals (receptor potentials).
Which modalities use the Ionotropic mechanism?
- Somatosensory
- Viscerosensory
- Auditory
- Vestibular
- Gustatory
Which modalitise use the Metabotropic Mechanism?
- Somatosensory
- Visual
- Olfactory
- Gustatory
What is the location attribute of stimuli?
The spatial arrangement of activated receptors within a sense organ conveys information regarding the stimulus
In the Somatosensory and Visual systems what kind of information does location convey?
the Receptors convey information about the location of the stimulus on the body or in space.
-location includes= discrimination of size, shape, and resolution of the fine details
How is the location of the stimulus determined?
Receptive fields of sensory neurons.
- each receptor responds only to stimulation within its field
- the greater the area of stimulation, the greater number of receptors that are stimulated
How does density of receptors affect the sensory system?
It determines how well the sensory system can resolve the detail of the stimuli in that area.
-Higher the density of receptors, the smaller the receptive fields, the finer the spatial resolution. (ex. 2 point discrimination)
How are differences in receptor density reflected?
Topographical maps in the CNS
How is spatial arrangement different in the auditory, vestibular, olfactory and gustatory systems?
The spatial arrangement of the receptors represents the energy spectrum of the modalities.
Ex. Auditory receptors are arranged according to the sound frequency to which they respond, not the location of the sound in space.
How is intensity of a stimuli determined?
- The amplitude of the receptor potential
2. Total number of active sensory neurons
How is intensity of a stimuli represented?
- Frequency of action potentials (frequency code)
- Number of activated receptors ( population code)
Ex. If you pinch a pencil, receptors around fingers are already activated. However, if you pinch harder, the frequency will increase.
How is Timing and Duration of a stimuli coded?
Represented by changes in the frequency of action potentials of sensory neurons
What are Rapidly Adapting Receptors?
- Respond only at the beginning and end of a stimulus
- Signal the rate at which the stimulus is applied or removed
What are Slowly Adapting Receptors?
- Respond to prolonged and constant stimulation
- Signal stimulus magnitude for minutes
What constitutes the common plan of sensory systems?
- Info is conveyed by populations of sensory neurons acting together
- Info is processed in a series of relay nuclei
- Inhibitory interneurons within each relay nucleus help sharpen contrast between stimuli
How do neurons act together to convey information and how does this involve submodalities?
- simultaneously activate receptors in parallel pathways
- specific submodalities depend on the combined activity of populations of receptors sensitive to overlapping energy changes.
Describe the order of relayed information
Population of Receptors (1st order neurons)–> 2nd order neurons–> Higher order neurons
Do 1st or 2nd order neurons have a bigger receptor field? Why?
2nd order neurons have a bigger and more complex receptive field because they receive information from a population of receptors
How do inhibitory neurons sharpen contrast between stimuli?
- They produce inhibitory regions within the receptive fields of higher order neurons
- This inhibitory region enhances the contrast between stimuli, improving the resolution of spatial detail.
