Chapter 9 Flashcards
Scotoma
small blind spot
Are we consciously aware of everything we see?
no. we are only aware of part of the visual information our brain is processing
Sensory receptors
specialized cells that transduce (convert) sensory energy into neural activity
Do sensory receptors respond to all sensory energy?
nope. they respond only to a narrow band of energy within each modality’s energy spectrum
Vision
light energy is concerted into chemical energy in the photoreceptors of the retina and the chemical energy is concerted into action potentials
Auditory System
air-pressure waves are converted first into mechanical energy, which activates the auditory receptors that produce action potentials
Somatosensory system
mechanical energy activates receptor cells that are sensitive to touch, pressure or pain. Somatosensory receptors in turn generate action potentials
Taste and Olfaction
various chemical molecules carried by the air or contained in food fit themselves into receptors of various shapes to activate action potentials
Human sensory abilities
are average
Receptive field
region of the visual world that stimulates a receptor cell or neuron
Photoreceptor cells
in the eye; each one points in a slightly different direction and thus has a unique receptive field
What does the brain do with receptive fields
identify sensory information, contrast information from each receptor field, help locate sensory events in space
Optic flow
streaming of visual stimuli that accompanies an observer’s forward movement through space
Auditory Flow
change in sound heard as a person moves past a sound source or asa sound source moves past a person
Usefulness of auditory and optic flow
tell us how fast we are going, whether we are moving or if the world is moving, what direction (straight, up, down) we are moving
Receptor density
determines the sensitivity of a sensory system
Color photoreceptors
small, densely packed to make sensitive color discrimination in bright light
black-white vision receptors
larger, more scattered, extremely sensitive to light
neural relays
all receptors connect to the cortex through a sequence of 3-4 intervening neurons; can modify information at different stages –> sensory system can mediate different responses
Location of relays
varies, some in brainstem, spinal cord, neocortex
Layers of neural relays
at each level a relay allows a sensory system to produce relevant actions that define the hierarchy of our motor behavior
Perceptions of speech sounds
influenced by the facial gestures of a speaker
Sensory coding
all sensory info from all systems is encoded by action potentials that travel along peripheral nerves in the somatic nervous system until they enter the spinal cord or brain and from there on nerve tracts within the CNS
How do we differentiate sensations?
different sensations are processed at distinct regions of cortex; learn through experience to distinguish them; each sensory system has a preferential link with certain kinds of reflex movements