Modern quantitative analysis of a historic database of midbrain single units from patients with cervical dystonia might support novel hypotheses for normal and abnormal head movements, according to a recent study. Researchers analyzed the unique database of pretectal neurons collected in the 1970s and 1980s during historic stereotactic surgeries aimed to treat cervical dystonia. This database is valuable because such recordings could otherwise never be obtained from humans. They found:
- 3 types of eye or neck movement sensitivity were found: eye-only neurons that responded to pure vertical eye movements, neck-only neurons sensitive to pure neck movements, and the combined eye-neck neurons that responded to eye and neck movements.
- There were 2 neuronal subtypes: burst-tonic and tonic.
- The eye-neck or eye-only neurons sustained their activity during eccentric gaze holding.
- In contrast, the response of neck-only and eye-neck neurons exponentially decayed during neck movements.
Sedov A, Popov V, Shabalov V, Raeva S, Jinnah HA, Shaikh AG. Physiology of midbrain head movement neurons in cervical dystonia. [Published online ahead of print February 20, 2017]. Mov Disord. doi:10.1002/mds.26948.