Editing Human echolocation (section)

==Mechanism==
[[Visual perception|Vision]] and [[hearing (sense)|hearing]] are akin in that each entails detection of reflected waves of energy. Vision processes light waves that travel from their source, bounce off surfaces throughout the environment and enter the eyes. Similarly, the auditory system processes sound waves as they travel from their source, bounce off surfaces and enter the ears. Both neural systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that their sense organs receive. In the case of sound these waves of reflected energy are referred to as [[Echo (phenomenon)|echoes]].

===Brain areas associated with echolocation===
[[Image:Brain image of blind echolocator.tif|thumb|right|400px|Echo-related activity in the brain of an early-blind, trained echolocator is shown on the left. There is no activity evident in the brain of a sighted person not so trained (shown on the right) listening to the same echoes]] Some blind people are skilled at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes.  Although few studies have been performed on the neural basis of human echolocation, those studies report activation of [[primary visual cortex]] during echolocation in blind expert echolocators.<ref name=":0" /><ref name="Thaler2011">{{cite journal |date=2011-05-25 |title=Neural correlates of natural human echolocation in early and late blind echolocation experts |journal=PLoS ONE |volume=6 |issue=5 |pages=e20162 |bibcode=2011PLoSO...620162T |doi=10.1371/journal.pone.0020162 |pmc=3102086 |pmid=21633496 |last1=Thaler |first1=Lore |last2=Arnott |first2=Stephen R. |last3=Goodale |first3=Melvyn A. |doi-access=free}}</ref>{{sfn|Hutchinson|2012}} The driving mechanism of this brain region remapping phenomenon is known as [[neuroplasticity]].

In a 2014 study by Thaler and colleagues,<ref>{{cite journal |author1=Thaler, L. |author2=Milne, J. L. |author3=Arnott, S. R. |author4=Kish, D. |author5=Goodale, M. A. |date=October 2013 |title=Neural correlates of motion processing through echolocation, source hearing, and vision in blind echolocation experts and sighted echolocation novices |journal=Journal of Neurophysiology |volume=111 |issue=1 |pages=112–127 |doi=10.1152/jn.00501.2013}}</ref> the researchers first made recordings of the clicks and their very faint echoes using tiny microphones placed in the ears of the blind echolocators as they stood outside and tried to identify different objects such as a car, a flag pole, and a tree. The researchers then played the recorded sounds back to the echolocators while their brain activity was being measured using [[functional magnetic resonance imaging]]. Remarkably, when the echolocation recordings were played back to the blind experts, not only did they perceive the objects based on the echoes, but they also showed activity in those areas of their brain that normally process visual information in sighted people, primarily the [[primary visual cortex]] or V1. This result is surprising, as visual areas are normally only active during visual tasks. The brain areas that process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed. Importantly, when the same experiment was carried out with sighted people who did not echolocate, these individuals could not perceive the objects and there was no echo-related activity anywhere in the brain. This suggests that the cortex of blind echolocators is plastic and reorganizes such that primary visual cortex, rather than any auditory area, becomes involved in the computation of echolocation tasks.

Despite this evidence, the extent to which activation in the visual cortex in blind echolocators contributes to echolocation abilities is unclear.<ref name=":1" /> As previously mentioned, sighted individuals have the ability to echolocate; however, they do not show comparable activation in visual cortex. This would suggest that sighted individuals use areas beyond visual cortex for echolocation.