4 - Sensory Systems Flashcards
signal transduction
how the physical world turns into electricity & chemical signals in the brain
receptive field
area from which a stimulus can activate a sensory receptor
rapidly adapting receptors
slowly adapting receptors
- respond at the onset of a stimulus
- respond for the duration of a stimulus
rods
- type of receptor cell in the eye
- rapidly adapting
- sensitive to dim light
- low response threshold
cones
- type of receptor cell in the eye
- slowly adapting
- sensitive to color & position
- high response threshold
exteroceptive receptors vs. interoceptive receptors
respond to external stimuli vs. internal stimuli
suprachiasmatic nucleus
- in the hypothalamus
- controls circadian rhythms of feeding & sleeping in response to light
pineal gland
controls long-term circadian rhythms through the release of melatonin
geniculostriate pathway
- pathway from retina to visual cortex
- pattern, color, & motion recognition
tectopulvinar pathway
- 2nd main visual pathway
- helps detect & orient visual stimulation
visual-form agnosia
- inability to recognize objects
- caused by damage to the geniculostriate pathway
visual ataxia
- inability to recognize where objects are located
- caused by damage to the tectopulvinar pathway
nociception
- perception of pain, temperature, & itch
- pain is perceived in the CNS
haptic receptors
- enable fine touch & pressure
- located in both superficial & deep skin layers
proprioception
- perception of body location & movement
- encapsulated nerve endings sensitive to stretch of muscles & tendons, & to joint movements
posterior spinothalamic tract
- one of 2 major somatosensory pathways
- for hapsis & proprioception
- fibers of somatosensory neurons are large, heavily myelinated, & rapidly adapting
anterior spinothalamic tract
- one of 2 major somatosensory pathways
- for nociception
- fibers of somatosensory neurons are small, less myelinated, & slowly adapting
Brown-Séquard Syndrome
- occurs when a unilateral spinal cord injury cuts somatosensory pathways in that 1/2 of the spinal cord
- causes loss of hapsis & proprioception unilaterally, & loss of nociception contralaterally
homunculus
a topographic map that represents the body surface on the primary somatosensory cortex
sensation
the registration of the sensory systems of physical/chemical energy from the environment & its transduction into nervous-system activity
perception
the subjective interpretation of sensation by the brain
synesthesia
- ability to perceive a stimulus of one sense as the sensation of a different sense
- can be either projectors or associators
