Which thalamic nucleus is most likely to result in hearing changes if damaged: Lateral geniculate (LGN), Medial geniculate (MGN), Pulvinar, Ventral posterior lateral (VPL), or Ventral posterior medial (VPM)?

Medial Geniculate Nucleus (MGN)

The medial geniculate nucleus (MGN) of the thalamus is the correct answer, as it is the obligatory relay station in the auditory pathway that transmits electrical signals from the brainstem to the auditory cortex in the temporal lobe. 1

Auditory Pathway Architecture

The auditory pathway follows a specific anatomical sequence that makes the MGN essential for hearing:

• Sound transduction begins at the cochlea, where hair cells in the organ of Corti convert mechanical sound wave energy into electrical neural impulses 1

• The electrical signal then travels through the auditory pathway, which includes the cranial nerve nucleus in the brainstem, superior olive, inferior colliculus, and critically, the medial geniculate body of the thalamus, before reaching the auditory cortex in the temporal lobe 1

• The MGN serves as the thalamic relay nucleus for auditory information, making it the only thalamic structure among the answer choices that directly processes auditory signals 1, 2

Why Other Options Are Incorrect

Lateral Geniculate Nucleus (LGN)

• The LGN is the visual relay nucleus, not auditory 1
• It processes visual information from the retina to the visual cortex 1

Ventral Posterior Lateral (VPL) and Ventral Posterior Medial (VPM)

• These are somatosensory relay nuclei 1
• VPM specifically relays tactile information from the face and whiskers (in rodents) to somatosensory cortex 1
• VPL relays body somatosensory information, not auditory signals 1

Pulvinar

• The pulvinar is involved in higher-order visual processing and attention, not primary auditory function 1
• It does not serve as a relay for the primary auditory pathway 1

Clinical Significance of MGN Damage

Damage to the MGN would disrupt the obligatory relay of auditory information to cortex, resulting in hearing deficits:

• MGN neurons show altered firing patterns in auditory pathology such as tinnitus and acoustic trauma 3, 4
• The MGN projects extensively to auditory cortex, amygdala, and striatum, with cortical projections being most dense 2
• Lesions interrupting this pathway would cause sensorineural hearing loss by preventing auditory signals from reaching the auditory cortex for conscious perception 1