The studies included in this thesis mainly evaluated in vivo the fast sensorimotor integration in the human sensorimotor area, by using a well-known TMS (transcranial magnetic stimulation) technique, called short-latency afferent inhibition (SAI).
Section 1 will review current knowledge on the biological and physiological basis of fast sensorimotor integration and its role in mild cognitive impairment and dementia.
Section 2 will report two studies. The first one is focused on using an innovative central sulcus-based mapping technique of SAI. We showed for the first time a centre-surround organization of fast sensorimotor integration in human motor hand area (Dubbioso et al., under review). The second study is mainly focused on the role of cerebellum in the modulation of somatosensory afferent pathway (Dubbioso et al. 2015). Indeed, we demonstrated that patients with pure cerebellar atrophy had an altered capability of cerebellar filtering or processing of time specific incoming sensory volleys, influencing the sensorimotor integration and plasticity of primary motor cortex (M1).
Section 3 will report two studies where SAI has been used as a tool to investigate functional involvement of central cholinergic circuits in two different types of cognitive impairment. In the first study we showed that patients with the adult form of Niemann Pick type C (NPC) are characterized by abnormal SAI (Dubbioso et al. 2014) whereas in the second one we found that SAI is normal in Parkinson disease (PD) patients with Freezing of Gait (FOG) (Dubbioso et al. 2015). Such results indicate that cognitive decline in NPC resembles from physiologically and clinical point of view primary form of cholinergic dementia such as Alzheimer disease. On the contrary, cognitive impairment in PD patients with FOG is mainly due to the involvement of non-cholinergic circuits, resembling forms of cognitive impairment dominated mainly by executive dysfunctions such as Fronto-temporal dementia
