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My work provides a better understanding of how tinnitus may
be triggered and as such could lead to the development of
better targeted drugs.
However, it is important to raise awareness that prolonged
exposure to sound levels within the range of an I-Pod causes
subtle changes in the brain which could cumulate into tinnitus.
1. Kaltenbach JA, Zacharek MA, Zhang J, Frederick S. 2004. Activity in the dorsal cochlear nucleus of
hamsters previously tested for tinnitus following intense tone exposure. Neuroscience letters 355:121-5
2. Zhang, J.S., and Kaltenbach, J.A. (1998). Increases in spontaneous activity in the dorsal cochlear
nucleus of the rat following exposure to high-intensity sound. Neurosci Lett 250, 197-200.
Aim of the study
Normal Hearing
Conclusion
I-PODS: AS DANGEROUS AS JET ENGINES?THOMAS TAGOE
Department of Cell Physiology and Pharmacology, Universty of Leicester
Prolonged exposure to sound intensities over 85 decibels (dB
SPL) can cause partial hearing loss and can eventually lead to
‘imaginary’ auditory perceptions known as tinnitus (1).
I-Pods and jet engines both exceed
85dB SPL and as such can be
equally damaging to the ears.
Therefore, the aim of this study is to
investigate if loud sound intensities
(110dB SPL) cause early changes
within the brain which could
eventually lead to tinnitus.
Sound is processed as electrical signals which pass
through many junctions or synapses within the brain.
The dorsal cochlear nucleus becomes overactive during the
tinnitus condition and it is also the first place in the brain to
process sound signals (2). Therefore, I tested how electrical
activity at synapses in the dorsal cochlear nucleus change
shortly after a prolonged exposure to loud sound.
The synapses serve as an
important point for controlling
the transfer of signals.
•After high frequency electrical
stimulations the size of the post
synaptic response increases.
•Using a drug to block type 2
receptors (NMDA receptors)
does not prevent this increase
I have shown that prolonged exposure to loud sound
affects how the brain processes sound signals.
This effect happens a few days after exposure and as such
could be an important step eventually leading to tinnitus.
Implications
References
Experimental approach
Auditory
Cortex
Dorsal
Cochlear
Nucleus
Prolonged exposure to loud
sound alters how the synapses
process the transfer of signals
•After high frequency electrical
stimulations, the size of the post
synaptic response decreases .
•Using a drug to block type 2
receptors (NMDA receptors)
prevents this decrease
10 20 30 400
0
1
1.2
1.6
No
rmali
sed
resp
on
se s
ize
Time (mins)
0.6
10 20 30 400Time (mins)
Electrical
signal
Transmitters
Receptors
Type 1 Type 2
Partial hearing loss
90-120 dB 110-140 dB
Electrical
signal
1.4
0.8
Normal hearing
Normal hearing
+ drug
Partial hearing loss
Partial hearing loss
+ drug
Synapse
Pre- Pre-
Post- Post-
Occupational
hazard
Recreational
pastime
or
Tinnitus
-to-
Signal transfer
alters
0
0.6
1.0
1.2
No
rmali
sed
resp
on
se s
ize
0.4
0.8
1.4
?