The Thaler team has prepared an excellent “exploratory research” paper that confirms several important open questions. However, their assertion related to human echolocation that “the neural processes underlying this ability are completely unknown” is at best parochial to the field of psychology. The areas of anatomy and electrophysiology have developed significant information on this subject previously and have been awaiting the arrival of significant fMRI data. As an example, the report on human echolocation (including initial evaluations relating to the same subject, EB) can be found at:

http://www.neuronresearch...

Thaler et al. did confirm;
1. The utility of a sensory substitution device (SSD). They provided statistical evidence answering this previously open question following the earlier work of Ciselet et al. in 1982. This confirmation is important to the perfection of the electrophysiological model of hearing in general and human echolocation in particular.
2. The fact that the visual cortex (area 17 or V1) of EB was in fact active in the absence of any visual input, and in response to auditory stimulation, thereby demonstrating the plasticity of the brain in the early blind.

They did not confirm;
1. That the location of EB’s primary auditory cortex remained in Brodmann’s area 41, 42 and Herschl’s gyrus like in sighted people. The above plasticity suggests it may have also migrated, possibly farther to the posterior regions of the temporal lobe or into the occipital lobe.

2. The expected role of the inferior colliculus in human echolocation. They did not present data showing activity, or lack thereof, in the inferior colliculus (IC) and the medial geniculate nucleus (MGN) during their test protocol. The neural model of hearing based on the Electrolytic Theory of the Neuron suggests the inferior colliculus is the center of echolocation activity related to ranging and angular location; and that the medial geniculate nucleus is the source of the signals passed to the auditory cortex related to the temporal aspects of auditory inputs (such as the outdoor “audio scenes” of the protocol).

It is understood that additional “applied research” tests are being planned by the Thaler group that will hopefully expand on these shortcomings and gather additional information.

The term “mediate” in their goal to “mediate natural human echolocation” is not an exclusive term. It is hoped they will explore a larger expanse of the brain in the future experiments.

It is also generally recognized that the fMRI technique remains spatial-resolution-limited and it may not be able to demonstrate activity in the IC and MGN. Neural models, such as found at http://www.neuronresearch... suggest only small areas of the IC and MGN may be required to perform the simple neural signal manipulation of interest in echolocation under their protocol.

It is hoped they will be able to improve the quality of their recording and playback equipment (flat to at least 20 kHz) to take advantage of the full capability of EB’s echolocation capability and remove the relevance of the test equipment from interpretation of the data.