Answer :
Final answer:
The visual and auditory pathways require third-order neurons synapsing in the thalamus. The olfactory pathway does not involve the thalamus, while the motor pathway is typically a two-neuron pathway that does not involve thalamic neurons. Therefore,the correct answer is option A and B.
Explanation:
Among the listed sensory pathways, the visual pathway and the auditory pathway require third-order neurons synapsing in the thalamus. In the visual system, the first synapse within the thalamus occurs at the lateral geniculate nucleus (LGN). From there, third-order neurons project to the primary visual cortex in the occipital lobe. Similarly, the auditory pathway also includes third-order neurons synapsing in the thalamus, specifically in the medial geniculate nucleus (MGN), before projecting to the primary auditory cortex in the temporal lobe.
On the other hand, the olfactory pathway does not involve the thalamus in its direct route to the brain. Olfactory sensory information is transmitted directly to the olfactory bulb and then to various parts of the olfactory cortex, bypassing the thalamus. Lastly, the motor pathway involves a two-neuron pathway for its voluntary muscular movements and does not typically involve third-order thalamic neurons.
