The thalamus serves as a sorting center in the brain, directing sensory information to the appropriate parts of the cerebral cortex for processing. The sensory cortex in the parietal lobe plays a crucial role in mapping sensations from different body parts. Nociceptive signals originating from a finger prick are transmitted through a three-neuron chain. Glutamate and substance P are important neurotransmitters involved in sending nociceptive signals from one neuron to another in the spinal cord.