CROSSMODAL PLASTICITY IN SPECIFIC AUDITORY CORTICES UNDERLIES VISUAL COMPENSATIONS IN THE DEAF "

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Kelley Golden
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1 Supplementary Online Materials To complement: CROSSMODAL PLASTICITY IN SPECIFIC AUDITORY CORTICES UNDERLIES VISUAL COMPENSATIONS IN THE DEAF " Stephen G. Lomber, M. Alex Meredith, and Andrej Kral 1

2 Supplementary Figure 1 Auditory brainstem responses evoked by stimulation with condensation clicks (50µsec) in closed field. Amplification: 100,000x, Filter: 100 Hz - 10kHz, 50 stimulus repetitions, repetition rate: 13 stimuli/sec. Electrode at vertex versus retroauricular electrode. Stimulus sound pressure level shown above each curve at the right. (a) Brainstem response of hearing cat. First significant difference from noise floor (determined from all single-trace responses at 5% significance level with two-tailed t-test) is indicated by the change from blue to red color (at 20 db SPL p.e.). Arrow indicates wave IV at lowest stimulus intensity. Brainstem response waves are numbered with Roman numerals I-V. (b) Absence of responses in congenitally deaf cat tested at one month of age up to 125 db SPL. Upper panel: left ear stimulated, lower panel: right ear stimulated. Asterisk marks electrical artifact from the loudspeaker at highest stimulation intensity. 2

Supplementary Figure 2 Behavioral testing equipment for visual localization and visual discriminations. (a) Acoustic and visual orienting arena.

3 Supplementary Figure 2 Behavioral testing equipment for visual localization and visual discriminations. (a) Acoustic and visual orienting arena. A loudspeaker (top circle) and a light-emitting diode (LED, black dot) were located above a food reward locus (lower circle) at each of thirteen regularly spaced (15º) intervals (for sake of clarity, only 30º intervals are labeled). A) The animal was first required to fixate on the central (0º) LED. B) It then had to orient to, and approach, a secondary acoustic (100ms broad-band noise) or visual (illumination of an LED) stimulus to receive a food reward. (b) Two-alternative forced-choice (2AFC) apparatus. The testing apparatus was a 52x29x41cm plexiglas box with a 14cm diameter opening at one end. This opening lead to a smaller plexiglas enclosure into which the animal placed its head. This chamber contained two hinged transparent response keys which the cat could depress with its nose to register a response. The stimuli could be viewed through the response keys. The monitors were located 28cm from the cat's eyes (thus 1cm on the screen was 2 visual degrees). Beneath the response keys was the food reward terminal, that dispensed a puree of beef liver and ground pork when the animal made a correct response. 3

4 Supplementary Figure 3 Polar plots of the visual localization responses from the deaf cats during unilateral and bilateral reversible deactivation. (a) Performance before and after cooling deactivation when cortex was warm (red) and active. (b-e), Performance while each locus in "deaf" auditory cortex was individually deactivated. The left column (i) shows data during unilateral deactivation in the left hemisphere, the center column (ii) shows data during bilateral deactivation, and the right column (iii) shows data during unilateral deactivation in the right hemisphere. The two concentric semicircles represent 50% and 100% correct response levels and the length of each bold line corresponds to the percentage of correct responses at each location tested. 4

5 Supplementary Figure 4 Motion detection thresholds for the deaf cats before and after cooling deactivation and during unilateral reversible deactivation. (a-d) Histograms showing mean±s.e.m. motion detection thresholds for the deaf cats while cortex was warm (red) and active and while individual regions in the left (dark blue) or right (light blue) hemisphere was unilaterally cooled and deactivated. 5

Supplementary Figure 5 Performance of the deaf cats, during simultaneous deactivation of PAF, DZ, A1, and AAF, on the five tasks for which they did not display superior visual abilities.

6 Supplementary Figure 5 Performance of the deaf cats, during simultaneous deactivation of PAF, DZ, A1, and AAF, on the five tasks for which they did not display superior visual abilities. For each task, data is presented while cortex was warm (red) and active, and during left (light blue), bilateral (dark blue), and right (turquoise) cooling when all four areas were deactivated. (a-d) Mean threshold±s.e.m. on grating acuity (a), Vernier acuity (b), orientation (c), and direction of motion (d), discriminations. Sample stimuli are shown for each task. (e) Performance on the velocity discrimination task. Data are presented as Weber fractions for six different stimulus velocities. 6

7 Supplementary Figure 6 Representative cooling deactivation reconstructions for the four cortical loci examined in the left hemisphere of a deaf cat. Blue regions indicate deactivation extent as plotted from direct temperature measurements. The areal borders were determined by using SMI-32 staining criteria as we have done previously 18. (a) Deactivation reconstruction showing a lateral (left is anterior) view of the left hemisphere with three horizontal sections in the vicinity of the cooling locus. (b-d) Reconstructions showing a lateral (left is anterior) and dorsal (top is anterior) view of the left hemisphere with three coronal sections in the vicinity of the deactivation locus. Sulcal abbreviations: pes - posterior ectosylvian sulcus, and ss - suprasylvian sulcus. 7

Binaural Hearing. Why two ears? Definitions

Binaural Hearing. Why two ears? Definitions Binaural Hearing Why two ears? Locating sounds in space: acuity is poorer than in vision by up to two orders of magnitude, but extends in all directions. Role in alerting and orienting? Separating sound