Auditory system vulnerability

Discussion points 1-3

Evidence that the auditory system of the brain has higher blood-flow and

metabolism

than any other

area

the brain [

1, 2

]. See figures 1

, 2,

and

Note: The deoxyglucose method has been extensively used in animal

research on

brain activity

responses to drugs and other factors. The inferior

colliculus has

consistently been found to have

the highest rate of glucose

utilization in every study.

Evidence that the auditory system is susceptible to damage by circulatory arrest

[

3-13

]. See figures

and

below.

Note: Asphyxia at birth was produced in monkeys by preventing the first

breath and

cutting off

circulation to the placenta (by clamping the umbilical

cord). Ischemic

bilaterally symmetric damage

to brainstem nuclei resulted.

Note: Current accepted practice in obstetrics is to clamp the umbilical cord

immediately after birth,

whether or not the first breath has occurred [

Evidence that the auditory system is susceptible to impairment by toxic

substances.

[

15-36

Note: Toxic substances cause bilaterally symmetric hemorrhagic (petechial)

lesions

of brainstem

nuclei (Wernicke’s encephalopathy). The lesions are

petechial,

resulting from increased blood

flow in response to the insult, with

bursting of

capillaries. Toxic substances impair aerobic

metabolism.

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Discussion points
Supporting evidence

>The auditory system
Final common pathway
Blood-brain barrier
Toxic injury
Brain maturation

Speech comprehension
Abstracts
Birth complications
Excerpts

Figures/ tables
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References
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