Lecture 19: The Auditory Cortex

Question 1

Where, anatomically, is the auditory cortex located

Answer 1

Part of temporal cortex

Buried

Pull up parietal and frontal lobe and look into sylvian fissure

Question 2

what brodmans area are the auditory cortex

Answer 2

BA 41 (main) and BA42

Question 3

What are the major cell types of the cerebral cortex

Answer 3

pyramidal and stellate

Question 4

important layers of the cerebral cortex

Answer 4

Layer 4 (stellate) –> receives input

Layer 5 (pyramidal) –> output layer

Question 5

functional organisation of cerebral cortex

Answer 5

Arranged in columns, each cell in a radial column respond to sound of the same frequency

Question 6

Neuroplasticity in hearing loss

Answer 6

Damage to periphery (hair cells) results in remodelling in the cortex

Question 7

can pathways be reactivated

Answer 7

a cochlea implant can reactivate missing pathways (more effective in young brains and shorter duration of deafness)

Question 8

how does cerebral cortex plasticity occur

Answer 8

change in the strength of the synapses

Question 9

The auditory fields of the auditory cortex based on tonotopic organisation

Answer 9

A1- primary in sound localisation (frequency and intensity), tonotopically mapped
A2- association cortex processing different parts of sound info
Dorsal Zone: inputs from both auditory and visual to identify an object in space

Question 10

what happened when they removed the A1

Answer 10

Animal could no longer localise sound in space

Question 11

crossmodal plasticity in hearing loss

Answer 11

adaptive feature of the brain, whereby the loss of one sensory modality (hearing) induces cortical reorganization that leads to enhanced sensory performance in remaining modalities

Question 12

If you were consistently exposed to a certain frequency, say 18 kHz,, would you have more or less of your A1 mapped to 18kHz?

Answer 12

You would have less, it is just part of the world, there is no usefulness to it

Question 13

If 18kHz was only played when food was present?

Answer 13

There would be more mapping for 18kHz

Question 14

Objective measures of auditory function

Answer 14

OAEs – for hair cell health

ABRs – for peripheral auditory system health

ACEP – for cortical function

All can be used to measure progress over time, or in response to different treatments

Question 15

what is used as an objective measure of auditory cortex function

Answer 15

auditory cortical evoked potentials (ACEP)

two key properties is amplitude and latency