Sensory Coding and Perception Flashcards
The 5 steps of sensory coding
Which 2 are sensory processing
Stimulus --------Sensory Processing Sensation---------Sensory Processing Perception Emotion Memory
Sensory Coding
What does the graph look like
How the brain detects and processes sensory stimuli
How the quantitative aspects of physical stimuli correlate with the neural activity they evoke
X-axis- Stimulus intensity
Y-axis- Neural activity
Sensation
The activation of sensory brain pathways by a physical stimulus
Perception
The extraction of a mental representation from a sensation
A sensory cue can give rise to different or misleading perceptions
Psychophysics
What does the graph look like
How the quantitative aspects of physical stimuli correlate with the sensations they evoke
X-axis- Stimulus intensity
Y-axis- Stimulus detection %
Psychometric curve
Receptor Neurons
Specialized cells that respond to physical sensory stimuli
“Respond”=electrochemically
Convert sensory stimuli into neural signals
What can a response in a receptor neuron evoke
A response in the neurons synaptically connected to it
That neuron can evoke a response in the next neuron
What is the response in neurons commonly called
Spikes
What are 2 ways to measure neuron spikes
- Electrophysiologically
2. Optically
Electrophysiological Recording
Intracellular- measures the membrane potential (including spikes)
Extracellular- Measures spikes and the local field potential (LFP)
Local Field Potential
Aggregate neural activity in the area
Calcium-Sensitive Dyes
Optical recording of action potentials
Molecules that become fluorescent in the presence of calcium
More calcium=more florescence
Spontaneous Firing
A sensory neuron occasionally fires spikes with no obvious relation to any sensory stimulus
A sensory stimulus can cause the neuron to change its firing rate
Neural code
Rate (frequency) code vs. Temporal code
Rate: information coded by a spike rate
Time: information coded by spike timing
Receptive field of a Neuron
A sensory neuron will respond to some stimuli and not others
The region of sensory space in which a stimulus will modify the firing of that neuron
What do spiking response give rise to
Our perception
What do our brain regions contain
Millions of neurons
These network responses are highly complex
Cortical Maps
“Topography”
Touch information from adjacent parts of the body are represented in adjacent parts in the cortex
Homunculus
“Tiny Man”
Refers to an orderly representation of the body in the brain
Why are the proportions of different cortical somatosensory representations different
Because of species-specific sensitivity
Cortical Plasticity
An experience can reshape sensory representations
A monkey was trained to perform a task that required using the tips of fingers 2, 3, and 4.
After training there is a substantial enlargement of the cortical representation of the stimulated fingers
Phantom Limb
In amputees, stimulation of face or arm can elicit phantom limb sensations
