Vision in the Hearing-Impaired: Enhanced or Deprived?
We perceive our environment using a wide variety of senses including
vision and audition and rely upon them individually or in combination
to make sense of our world.
Conventional neuroscience dictates that the neuroplastic processes
within the brain allow for the efficient use of its available resources.
This results in the phenomenon that is not necessarily beneficial,
for example the expansion of somatosensory maps following
limb amputation results in spurious perceptual events known
as “phantom limb pain”1 or untreated amblyopia results in
the profound loss of visual acuity.
How this process works during the complete loss of sensory information
from one modality is still a topic of debate. One theory suggests
that developmentally the loss of one sense, say hearing, will adversely
affect other senses as well, this is known as the perceptual deficit hypothesis.
On the other hand, there is mounting evidence that when one sensory system
affected, there is the reallocation of resources to another system
resulting in an enhancement of other sensory systems.
This is termed as the perceptual compensatory hypothesis and is believed
to be the direct result of the cross-modal plasticity properties of the brain.
In this mini-review, we aim to explore both these hypotheses.
The first hypothesis states that a significant deficit in one sensory
modality affects the development and organization of the other
sensory systems. This is termed as the perceptual deficit hypothesis.
In the case of hearing-impaired, the perceptual deficit hypothesis
predicts hearing-impaired individuals will exhibit poorer visual and
tactile perceptual performance.
The secondary assumption is that the lack of one sensory input adversely
affects the complex tasks such as language which needs significant interaction
between the different senses.
Neuro Open J. 2019; 6(1): 6-9. doi: 10.17140/NOJ-6-130