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. 2015 Aug 4;9:37. doi: 10.3389/fncir.2015.00037

Figure 3.

Figure 3

(A) Schematic diagram of the electrode array used in this study. (B) Example of a typical multiunit frequency response area (FRA) recorded in ICc. The blue-to-yellow color scale indicates the multiunit response strength observed for pure tones presented at the frequency and intensity indicated on the x- and y-axis respectively. The best frequency (BF) indicated by the green arrow was measured by summing responses for stimulus amplitudes >50 dB SPL. (C) FRAs collected during one medio-lateral multi-electrode array penetration through the inferior colliculus (IC). Each of the 64 squares is one FRA, with x- and y-axis ranges as in (B). Channel 27 is highlighted by a green frame, as it is the same data as that shown in more detail in (B). FRAs from recording sites outside the ICc are shown in a desaturated color map. (D) BFs derived from the data shown in (C) plotted as a color-coded tonotopic map superimposed to scale, onto a Nissl stained histological section through the corresponding part of the IC. The color of the filled circles indicates the BF for each recording site according to the color scale on the right. Large filled circles show BFs of recording sites located within ICc, small circles indicate recording sites outside ICc. The axes show coordinates in mm from the mid-line and the dorsal edge of the midbrain respectively. DC, dorsal cortex of the IC; LS, lateral shell of the IC; PAG, periaqueducal gray. (E) FRAs as in (C), recorded during a multielectrode penetration oriented along the sagittal plane. Two of the channels on this multielectrode array were faulty, hence two FRAs are missing, one at the top right, the other in the bottom row. (F) Composite showing the BFs obtained from the data shown in (E), as well as the data from a second recording location, 0.5 mm deeper, superimposed to scale onto a photo-micrograph of a sagital section through the gerbil IC taken from page 21 of Cant and Benson (2005; by kind permission of the publisher). SCs, superior colliculus, superficial layers; SCd, superior colliculus, deep layers.