Lecture 7 Flashcards
Sensory Structures and Processes
variation in human sensory capacity is due to …
- genetics
- maturation
- circadian rhythm
- experience / training
- fatigue
- injury / disease
- etc
6 categories of human sensory receptors
- chemosensor
- mechanoreceptor
- noiceptor
- photoreceptor
- thermoreceptor
- phono-receptors
what is the first step in the process of sensation
reception - ability of receptor to absorb energy of a stimulus
what is the second step in the process of sensation
transduction - conversion of stimulus energy into a membrane potential, a change in permeability of a post synaptic membrane often graded
what is the third step in the process of sensation
transmission - receptor potentials transmitted via AP’s to CNS
what is the fourth step in the process of sensation
integration - CNS processing of frequency of receptor potentials
what is sensation coded as
frequency of neurons firing
a decrease in responsiveness by receptors due to continual stimulation usually means what has occurred
accomodation of a stimulus
a uniformly maintained stimulus of constant intensity is perceived as what over time (and an example)
perceived as progressively weaker with time
- example = when you put your clothes on in the morning you can feel them, but this becomes dull
a variable intensity stimulus of shorter durations is perceived as what over time
perceived as progressively stronger over time
what is meant by sensation
detect the information
what is perception
understand it, to make sense of it
what are the two roles of the primary somatosensory cortex and how is it organised
- integration of sensory information
- provides meaning to our perceptions topographically
- topographically organised
what occurs if there are lesions to the primary somatosensory cortex (3)
- defective localisation
- loss of proprioception
- tactile agnosia
what is tactile agnosia
trouble to identify an object by touch alone
why cant we tickle ourselves
the brain anticipates touch and turn down sensitivity threshold
what are the three main types of receptors
- interoceptors
- proprioceptors
- exteroceptors
what are interoceptors
states our internal organs (not so relevant for motor control)
what are proprioceptors
information about our own movements
what are examples of proprioceptors
- muscle receptors
- joint receptors
- cutaneous receptors
- vestibular system
what are exteroceptors
information about the movement of objects in the environment
examples of exteroceptors (2)
- vision
- audition
what is proprioception
sensation and perception of the position and movement of limbs, head and trunk
what are muscle spindles parallel to
spindles are parallel to muscle fibres
