I've heard of the 'cerebellar clamp' that quickly causes a temporary suppression in vestibular activity from both sides after a unilateral insult. Is that right?
Answer: It sounds like you might be referring to the ‘cerebellar shutdown’ hypothesis. This hypothesis concerns the process of static vestibular compensation following a unilateral vestibular insult whereby loss of afferent sensory input from the vestibular periphery leads to vertigo, nystagmus and postural symptoms. The process of compensation, a very clear example of neural plasticity, restores neural activity in vestibular reflexes despite a lesion, and thereby alleviates static (head still) symptoms of imbalance. This process takes several days in mammalian species and likely involves several mechanisms such as expression of synaptic receptors, altered cell membrane excitability and rebalancing between inhibitory and excitatory neural circuitry. The cerebellar shutdown hypothesis suggests a bilateral drop in activity takes place within hours of a unilateral lesion, in at least some brainstem vestibular nuclei. If true, one would expect an alleviation of symptoms and a bilateral loss of postural muscle tone, which is not typically observed. For a more detailed overview please see Smith and Curthoys (1989)
References and caveats
Smith, P.F. and Curthoys I.S. (1989) Mechanisms of recovery following unilateral labyrinthectomy: a review. Brain Research Reviews 14, 155-180