Introduction to Perception Flashcards
(30 cards)
Sensation: definition
Awareness do to the stimulation of a sense organ
Sensation
What are the three components of sensory systems? Which ones do we know the most about
Receptors: these are the sense organs. This is where sensation starts and this is what we know the most about
Pathways
Target areas
What are the three common features of the various sensory modalities?
- A physical stimulus
- Transformation of the stimulus into neuronal signals (the stimulus has to be transformed into a signal so that we can PERCEIVE it.
- A response to the signals in the form of a perception or a conscious experience of sensation
Perception: definition
An internal construction of the external world according to the CNS; the conscious experience of sensation
Perception
What is the distinction between the stimulus and perception?
Our perceptions of colors, tomes, smells, and tastes are mental creations constructed by the brain in response to the sensory experience. They do not exist as such outside the brain.
Coding Sensory Information
What is a neural Code?
It describes the relationship between the activity in a specified neural population and its functional consequences.
Coding Sensory Information
What are the 4 attributes of stimuli that all sensory systems encode?
Modality
Location
Intensity
Timing/Duration
Coding Sensory Information: Modality
Definition
Defines the general class of stimulus
It is determined by the stimulus energy (the sensory stimulus) and the receptors specialized to sense that energy
Coding Sensory Information: Modality
What is the labeled line code?
The coding mechanism for a stimulus modality
Receptors respond to specific stimuli, and pathways carrying sensory information centrally are therefore also specific, forming a “labelled line” regarding a particular stimulus
Coding Sensory Information: Modality
What is the rose of the sensory receptors?
The are the first cell (or region of a cell) in each sensory pathway; they are morphologically specialized to transform stimulus energy into electrical energy.
Coding Sensory Information: Modality
How are sensory receptors classified?
Based on the type of stimulus energy to which they are most sensitive.
Coding Sensory Information: Modality
What are the properties of sensory receptors?
Each receptor responds to a narrow range of stimulus energy.
Receptors transduce stimulus energy into electrical signals (receptor potentials)
Coding Sensory Information: Modality
What are mechanisms used by sensory receptors to transduce stimulus energy into a signal? What are they similar to?
Mechanisms are similar to those used by the receptors at chemical synapses. Thy can be
Ionotropic receptors: These are present in the somatosensory, Viscerosensory, Auditory, Vestibular, and Gustatory systems; these directly open ion channels and mediate fast transmission
Metabotropic Receptors: These are present tin the somatosensory, visual, olfactory, and gustatory systems; indirectly associated with ion channels via g-proteins and second messengers; mediate slower transmission
Coding Sensory Information: Location
How do receptors code for location of a stimulus (visual and somatosensory systems)
Spatial arrangement of the activated receptors conveys information about the location of the stimulus on the body (somatosensory) or in space (visual); location is determined by the receptive fields of the sensory neurons that are being activated.
Coding Sensory Information: Location
What aspects of the stimulus are encompassed by the location?
Discrimination in the size and shape of an object.
Resolution of the fine detail of a stimulus.
Coding Sensory Information: Location
What is the role or receptor density?
The density of receptors in a given area determines how well the sensory system can resolve the detail in the stimuli in that area.
Coding Sensory Information: Location
What is the relationship between receptor density and the size of the receptive fields and spatial resolution?
The higher the density of the receptors, the smaller the receptive fields, and the finer the spatial resolution.
These differences are represented by topographical maps in the CNS (like homunculus)
Coding Sensory Information: Location
What is the role of the spatial arrangement of the receptors in the Auditory, Vestibular, Olfactory, and Gustatory systems?
The spatial organization of the receptors in these modalities represents the energy spectrum of each modality rather than information about the location of the stimuli on the body or in space.
Coding Sensory Information: Intensity
What determines the intensity of the signal?
Amplitude of the receptor potential (these are at the INPUT part of the neuron and are graded, local potentials)
Total number of active sensory neurons
Coding Sensory Information: Intensity
What is the stimulus threshold?
The lowest stimulus amplitude that can be detected - the least amount of receptor potential that needs to signal the neuron to set off an action potential.
Different receptors have different stimulus thresholds
Coding Sensory Information: Intensity
How is intensity represented in the signal?
Represented by the FREQUENCY of action potentials (frequency code) and the NUMBER of activated receptors (population code) of sensory neurons.
Coding Sensory Information: Timing/Duration
What determines the timing or duration of the signal?
Changes in the PATTERN of sensory neuron activity.
Coding Sensory Information: Timing/Duration
Do receptors adapt to constant stimulation? How?
Yes. They can adapt either rapidly or slowly but the mechanism for this is not well understood.
Coding Sensory Information: Timing/Duration
Rapidly Adapting Receptors - when do they respond? what do they signal?
Respond only at the beginning and end of a stimulus.
Signal the rate at which the stimulus is applied or removed.
