Animals: Orientation from birth

The bat auditory cortex is prewired for echolation - the process by which they detect distance from objects and surface texture - suggests a paper in Nature Communications this week. The work reports that basic cortical features, in the form of echo-delay-tuned neurons, are already established before bats actively explore their surroundings by echolation.

Neuronal computation of object distance using echo delay is a task that bats must master for spatial orientation and the capture of prey. It is unknown, however, whether neuronal correlates of active space perception are established though experience dependent plasticity or by innate mechanisms.Cornelia Voss and colleagues demonstrate in two bat species that differ in foraging behaviour that in the first postnatal week, the dorsal auditory cortex already contains functional circuits, which they show are capable of calculating distances from the temporal separation of simulated pulses and echos. This means that they are present and active before onset of echolation and flight, They suggest that this innate cortical mechanism for sonar ranging should enhance the survival of juvenile bats when they first engage in active echolation behaviour and flight.

The authors note however, that this work does not rule out plasticity and experience dependent changes in delay tuning during maturation - something that has been demonstrated in other mammals. It also doesn’t currently consider vocalisations in bats and whether feedback systems play a part, as they do in human infants.

doi: 10.1038/ncomms1782

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