Fig. 4.

Effects of cortical lesions on sound-evoked head orienting responses. Final bearing of the initial head movement for the same representative cases shown in Fig. 2 (F0140 and F0317) in response to sounds of 2 different durations, 1,000 (A) and 40 ms (B), before and after the lesions were made. Each plot shows in grayscale the conditional probability of different final head bearings, with a bin size of 7.5°, for each target location. For each plot the value of the overall mutual information between final bearing and target location is shown at the bottom right. As with the approach-to-target responses, little effect was seen for long duration noise bursts (A), whereas for brief sounds, the clear correlation observed between the final head bearing and target location in the prelesion data was seriously disrupted after extensive cortical lesions, but only slightly affected after restricted lesions (B).