Download MCB105 QUIZ 5 2016 wA

MCB105 QUIZ 5 2016
NAME: _________________________
/10
Knudsen (1998). Capacity for plasticity in the adult owl auditory system
1) Eric Knudsen single-handedly demonstrated that barn owls that experienced a shift of their
visual field as juveniles exhibit neuronal plasticity as adults.
a) In which neurons was this plasticity shown? [1]
OT neurons with both auditory and visual responses
b) How is this change measured (explain or draw)? [1]
Measure the same OT neuron before and after prism fitting. Compare the visual receptive field
(0degs) with ITD tuning. Draw ITD/best response curve shifts.
2) How did Eric Knudsen show that there is a limit to the capacity for plasticity in the adult
auditory system? [1]
He shifted the visual receptive field of the adults with juvenile shifted visual fields (R23) to angles
they were not previously exposed (L23 and R34). The tectal auditory responses of these animals
showed that they are incapable of re-tuning their responses to these novel visual shifts.etrograde
tracing
Gutfreund et al. (2002) Gated visual input to the central auditory system
3) What did Gutfreund et al. look for in the external nucleus of the inferior colliculus (ICX) in barn
owls and why? [1]
instructive signal/ visual responses to allow alignment of visual and auditory space
- their recordings showed that visual receptive fields of ICX neurons were restricted and quite
similar in size to the ones observed in the OT.
b) How did they open the 'gate' that prevented these findings in previous investigations? Explain
the methods in detail. [2]
they pharmacologically block gabaergic transmission in the OT and record from the ICX while
presenting visual stimulus.
4) Which experiment in Gutfreund et al. provides evidence for a neural mechanism to align
bimodal topographic maps in the ICX? [2]
LED flashing in center of VRF. Move sound around owl. Measure activity in ICX: visual responses
in the ICX are dramatically reduced when the ITD of an accompanying sound matches the ITD
predicted for the visual receptive field.
b) Given their findings, what do the authors suggest how this mechanism functions? [2]
These findings suggest that visual information would excite the ICX only when it is misaligned
with the auditory stimulus. This visual input would then adjust the representation of auditory
localization cues in the ICX to match the visual representation of space.