lecture 13 Flashcards
somatic senses
- touch
- temp
- itch
- pain
- proprioception
—-> goes to primary cortex in parietal lobe where it is perceived
if a signal reaches the cerebral cortex
stimulus enters our consciousness
if signal does not reach the cerebral cortex
- stimulus is processed and a movement is elicited w/ out our conscious awareness (heart rate, digestion)
- not strong enough (not aware)
proprioception
awareness of where you are in space (you know you’re sitting)
conscious stimulus processing (special senses)
- vision—> goes to visual cortex in occipital lobe
- hearing —> goes to auditory cortex in temporal lobe
- smell and taste —> goes to dedicated region between frontal and temporal lobe
- equilibrium (balance) —> involves vestibular apparatus in inner ear
sensory receptors
- convert stimulus into intracellular response
- the may or may not be neurons
type of receptor:
1. chemoreceptor
2. mechanoreceptor
3. photoreceptor
4. thermoreceptor
a change in membrane potential of receptor cell
receptor potential
when a light photons fall on retina in the eye, rods and cones _________
hyperpolarize
when skin is touched, touch receptors _______
depolarize
Transduction
Stimulus is converted into an intracellular response
Sensory receptors that are neurons
Transduction occurs at the receptor end of primary sensory neurons
Example 1: pain and temperature receptors w/ free nerve endings in the dermis of the skin
- unmylinated
- synapse in dorsal region (gray matter) of spinal cord
- slow
Example 2: Pressure (in closed nerve endings)
- mylinated
- synapse in dorsal region (gray matter) in spinal cord
- fast
In response to their stimulus (pain, temperature, pressure) they produce action potentials
Sensory receptors that are not neurons
- Sensory cell is separate from the primary sensory neurons
- special senses (vision, hearing, taste) receptors are cells that release neurotransmitters onto a partner primary neuron to fire an AP (indirectly)
- example: inner ear has hair cells that is caused my finger like projections called cilia that respond when their is mechanical energy
- intracellular response is receptor potential
- exception is olfactory system (smell)
stimulus modality
- determined by sensory receptor activated and what area in the brain the sensory signal is sent too
e.g. when photoreceptors are activated you will perceive light because photoreceptor send signals along visual pathways to visual cortex in occipital lobe
Label line coding: when you activate a certain receptor (photoreceptor) and that info always goes to the same place (visual cortex) then that info will always be perceived as light
Example: when u press on your eyes “seeing stars” signal from photoreceptors are always perceived as “light” even if they were activated by another stimulus such as mechanical stress
when would you not get 2 point discrimination?
- when all primary neurons converge and synapse onto a single secondary sensory neuron
- convergence creates large receptive fields
when would you get 2 point discrimination?
- when each primary neuron has a secondary neuron
- when fewer neurons converge, secondary receptive fields are much smaller