Final answer:
The exact number of neurons conducting sensory impulses from the periphery to the postcentral gyrus cannot be quantified as a specific figure. This process involves a complex network including spinal or cranial nerves, with pathways that involve the dorsal root ganglia, spinal cord, brain stem, thalamus, and finally the cerebral cortex.
Step-by-step explanation:
The number of neurons that conduct sensory impulses from the periphery to the postcentral gyrus is not specified as a fixed number, as this involves a complex network of interconnected neural pathways.
The sensory information from the periphery enters the central nervous system through either the spinal nerves or the cranial nerves.
In the case of the spinal nerves, this information travels through the dorsal root ganglia, across the spinal cord, ascends the brain stem via the medial lemniscus, synapses in the thalamus.
And it eventually projects to the postcentral gyrus of the cerebral cortex, which is responsible for processing somatosensory stimuli and creating conscious perception of the stimulus.
The cranial nerves may also convey sensory information to the brain, with each type of nerve having a different pathway and connection to the brain, depending on whether they are strictly sensory or mixed sensory and motor nerves.
However, the exact number of neurons involved in conveying sensory information from the body through spinal nerves to the postcentral gyrus would be an enormously intricate figure due to the complex and variable nature of neuronal connections.