NROS 418 Exam 3 questions with correct answers

Define adaptation - Answer Reduction of sensory responsiveness when stimulation is unchanging. It prevents us from having to respond continuously to unimportant information Explain the adaptation process for the visual pathway - Answer Low levels of Ca++ activate recoverin which activates rhodopsin kinase, phosphorylates rhodopsin, arrestin binds and shuts off pathway Explain the adaptation process for the auditory pathway - Answer (prolonged stimulus) Stereocilia are bent, tip links are stretched, channel opens. There is an interface plaque on the tall stereocilia which is where the tip link attaches. On the internal side is a myosin motor that is associated with that plaque. Under normal circumstances, the tip link is trying to pull down where the myosin motor is trying to pull up. When you open the channels that allow in K+ and Ca++, the Ca++ comes in, binds to calmodulin which is associated with the neck of the myosin which causes it to decrease its upward movement so it is coming down the actin filaments. As the motor travels down, the stretch on the tip link decreases so the channels open decreases. Decrease responsiveness of that hair cell to that degree of bending What is a receptive field? - Answer The region of sensory space whose stimulation results in a change in firing rate of the neuron Primary receptor pick up information from spatial domain in organ where stimulation occurs, second/third order neuron receive summation of multiple stimuli from prior neurons, higher order are most complex as they get the most summation of stimuli Why does the organization of the eye guarantee that we have a blind spot? Why can't we normally detect the blind spot? - Answer The axons of retinal ganglion cells converge at the optic disc and extend through the retina a