Brain cell in the context of Interneuron

In neuroscience, neuronal tuning refers to the hypothesized property of brain cells by which they selectively represent a particular type of sensory, association, motor, or cognitive information. Some neuronal responses have been hypothesized to be optimally tuned to specific patterns through experience. Neuronal tuning can be strong and sharp, as observed in primary visual cortex (area V1), or weak and broad, as observed in neural ensembles. Single neurons are hypothesized to be simultaneously tuned to several modalities, such as visual, auditory, and olfactory. Neurons hypothesized to be tuned to different signals are often hypothesized to integrate information from the different sources. In computational models called neural networks, such integration is the major principle of operation. The best examples of neuronal tuning can be seen in the visual, auditory, olfactory, somatosensory, and memory systems, although due to the small number of stimuli tested the generality of neuronal tuning claims is still an open question.

Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, each condition presents differently. Neurofibromatosis type I (NF1) is typically characterized by café au lait spots (light-brown flat patches of skin), neurofibromas (small bumps in or under the skin), scoliosis (side-way curvature of the back), and headaches. Neurofibromatosis type II (NF2), on the other hand, may present with early-onset hearing loss, cataracts, tinnitus, difficulty walking or maintaining balance, and muscle atrophy. The third type is called schwannomatosis and often presents in early adulthood with widespread pain, numbness, or tingling due to nerve compression.

The cause is a genetic mutation in certain oncogenes. These can be inherited, or in about half of cases spontaneously occur during early development. Different mutations result in the three types of NF. Neurofibromatosis arise from the supporting cells of the nervous system rather than the neurons themselves. In NF1, the tumors are neurofibromas (tumors of the peripheral nerves), while in NF2 and schwannomatosis tumors of Schwann cells are more common. Diagnosis is typically based on symptoms, examination, medical imaging, and biopsy. Genetic testing may rarely be done to support the diagnosis.