Alicia is being tickled by her older sister. which divisions of the nervous system are receiving the signals from her sister's fingers?

In this case, when Alicia is being tickled by her older sister, the divisions of the nervous system which are responsible for receiving the signals from her sister’s fingers are called somatosensory cortex and anterior cingulated cortex nervous system.

When you are touched lightly, the effect of having that ticklish sensation is caused by the analysis of two regions of the brain. For example, when our brain analyses the pressure of the touch, this is the work of the somatosensory cortex. On the other hand, as soon as something touches your skin, the signal sent from the skin's sensory receptors also passes through the anterior cingulated cortex. This is where the pleasant feelings are governed.