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The cornea has been a focus of animal electrophysiological research for decades, but little is known regarding its cortical representation in the human brain. This study attempts to localize the somatotopic representation of the cornea to painful stimuli in human primary somatosensory cortex using functional magnetic resonance imaging (fMRI). In this case study, a subject was imaged at 3T while bright light was presented in a block-design, which either produced pain and blinking (during photophobia) or blinking alone (after recovery from photophobia). Pain and blinking produced precisely localized activations in primary somatosensory cortex and primary motor cortex. These results indicate that noxious stimulation of the cornea can produce somatotopic activation in primary somatosensory cortex. This finding opens future avenues of research to evaluate the relationship between corneal pain and central brain mechanisms relating to the development of chronic pain conditions, such as dry eye-like symptoms.
Moulton EA, Becerra L, Rosenthal P, Borsook D.
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P.A.I.N. Group, Center for Pain and the Brain, Children's Hospital Boston, Massachusetts General Hospital, McLean Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
How did I deduce this? Well, the sclera of my eyes hurt, a lot. My corneas, not at all except for around the edges?!? Hmm.... My Ophthalmologist triggered this when she said something like "if you have corneal de-sensitivity you should not feel any pain." This made me more cognisent of my pain and where it actual ... resides?
Well, I can tell you that the center of my corneas feel nothing. My scleras feel like they're burning and raw. My eyelid margins feel irritated and my eyelids feel chapped.
Not sure this was relevant or helped anyone ...