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Hemimasticatory spasm probably is the consequence of an abnormal trigeminal hyperexcitability likely induced by the demyelinating lesion of its peripheral motor pathway. The main neurophysiological abnormalities may persist unmodified over a long course of the disease and allow the differential diagnosis of HMS from oromandibular dystonia and temporomandibular dysfunction (TMD).

Measurement of motor cortex excitability using paired-pulse transcranial magnetic stimulation (pTMS) has been proposed for the early diagnosis of Alzheimer's disease (AD) and could also be useful for monitoring treatment response and disease progression. However, studies conducted at the pre-dementia stage of AD are scarce, very few long-term data are available, and correlations between cortical excitability and cognitive performance have not been addressed. Eleven patients with mild cognitive impairment (MCI) that converted to AD-related dementia and 12 elderly control subjects were selected for this study. Cognitive assessments and pTMS were conducted at baseline in the two groups and also after 4 and 21 months of treatment with donepezil in the AD group. Non-parametric statistics were used to compare cortical excitability between the two study groups at baseline and to analyse disease course in the AD group. Correlation analysis was performed to investigate associations between cortical excitability and cognitive performance. Short-latency intracortical inhibition (SICI) and intracortical facilitation were reduced in AD patients. However, there was high inter-individual variability, and statistical significance was only attained at a 2-ms interstimulus interval (ISI). A trend towards recovery of 2-ms SICI was observed after treatment with donepezil. Baseline cortical excitability at 300 ms was associated with better cognitive performance in AD patients. Although the present results do not support a role for pTMS in the early diagnosis of late-onset AD, a potential role in prediction of treatment response and understanding of disease mechanisms emerged.

The characteristics of the circadian rhythm of locomotor activity in the crayfish Procambarus clarkii during ontogeny under constant darkness and light-dark (LD 12:12) conditions were studied in 132 juvenile crayfish, aged 10-140 days, divided in four groups. All animals were individually monitored with a motor activity recording system. Activity was quantitatively and qualitatively analyzed. All ages showed a circadian rhythm, although the probability of its appearance increased with age. Period values oscillated between 25.0 h in group I (2-4-week-old animals) and 24.3 h in group IV (16-20-week-old animals with more than 6 molts), but always with a high standard deviation. Groups II (5-10-week-old animals) and IV showed a statistically significant bimodal nonrandom synchrony of phases. The activity/ rest relationship diminishes as development progresses and is most uniform in group IV. We discuss the possibility that the pacemaker system responsible for this rhythm might be present from the moment of eclosion, but the coupling strength of this system with the effectors might change along development. The results presented in this work seem to indicate that the central pacemakers responsible for the activity and the ERG rhythm are not the same.

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