Figure 3. Range tuning of midbrain neurons.

(A) A cartoon representation showing the target range estimation in a free-flying echolocating bat. The difference between the call production time (T0, red arrow) and the echo arrival time (TE, green arrow) is a function of target distance. (B) Sensory responses of a single neuron to echo returning at a specific delay with respect to sonar vocal onset from actual trial data. The arrival time of the first echo (TE₁) is indicated with a green arrow, the second echo (TE₂ – from a more distant object) is indicated with a blue arrow. Note that this neuron responds to the echo arriving at ~10 milliseconds. (C) When the echo returns at a shorter delay, the neuron does not respond; and the neuron similarly does not respond to longer pulse-echo delays. (D) Histogram showing target distance tuning (i.e. pulse-echo delay tuning) for the neuron in panel B and C. Note the narrow echo delay tuning curve.

Figure 3—figure supplement 1. Spatial coverage during the experiment.

(A) Flight paths (black lines), vocalizations (yellow dots) and obstacles (pink circles) for one recording session. (B) Histogram of calls per recording session. (C) Histogram of number of echoes per recording session. (D) All egocentric azimuthal angles for obstacles encountered in flight. (E) All egocentric ranges for obstacles encountered in flight. (F) All egocentric elevation angles for obstacles encountered in flight. Open bars indicate limited coverage (one SD below mean coverage of that dimension) and these regions were not included in the analysis.

Figure 3—figure supplement 2. Spatial tuning in azimuth and elevation.

(A) Histogram of azimuthal tuning for the neuron in Figure 3B. Inset is a polar-plot representation of azimuthal tuning. (B) Histogram of elevation tuning for the neuron in panel Figure 3B. Inset is a polar-plot representation of elevation tuning. Note the narrow tuning curves.