Neurobiological basis of state-dependent control of motor behaviors

Abstract

We note the importance of an appropriate combination of excitability for the higher (neocortex, basal ganglia, and limbic system) and lower (brainstem-spinal cord) motor systems could be necessary for normal behavior during wakefulness and REM sleep.Neurotransmitters such as acetylcholine, the monoamines, GABA, and the orexins, would regulate the background excitability of the higher and lower motor systems so that an interaction of these systems could be appropriately maintained. Pathophysiological mechanisms of sleep deficiency may be induced by not only an organic disturbance of brain structures (hardware) but also by dysfunction of the neurotransmitter systems (software). From these considerations, we provide a hypothetical model for "state-dependent interaction of the higher and lower motor systems" for understanding normal behavior and pathophysiological mechanisms of sleep-related disorders such as narcolepsy and the REM-sleep behavioral syndrome.2

Possible Contribution of the Basal Ganglia Brainstem System to the Pathogenesis of Parkinson’s Disease

“…On the basis of findings of our studies (Takakusaki et al, 2004b(Takakusaki et al, , 2006 as well as those of previous works (Grillner 1981, Mori 1987, Rossignol 1996, current perception of the neuronal pathways involved in locomotor control is illustrated in Fig.1A. Motor behaviors require the recruitment of the activities of the entire nervous system (Fig.1A) and musculoskeletal systems (Fig.1B).…”

“…As show in Fig.2D, cholinergic neurons were abundantly distributed in the area corresponding to the inhibitory region, indicating that an activation of cholinergic neurons requires muscle tone suppression (Takakusaki et al, 2003a). Our current perception of neuronal mechanisms of controlling postural muscle tone and locomotion is shown in Fig.3A on the basis of previous studies (Grillner 1981;Mori 1987;Rossignol 1996;Takakusaki et al, 2004bTakakusaki et al, , 2006. Three locomotor regions are identified.…”

“…In contrast, the inhibitory system suppresses the activity of the coerulospinal tract (Mileykovskiy et al, 2000). Accordingly muscle tone can be regulated by a counterbalance between the inhibitory and the excitatory systems (Takakusaki et al, 2006). It was reported that a patient with a lesion in the dorsolateral mesopontine tegmentum did not lose muscle tone during REM sleep ("REM without atonia") (Boeve et al, 2007;Culebras & Moore 1989).…”

“…Consequently, our idea is that basal ganglia output from the SNr may affect awakesleep cycles by modulating the activity of the ARAS through dual mechanisms (Fig.7D). One is through direct nigro-thalamic projection, and the other, which is considered in this study, is though indirect connections via the PPN (Takakusaki et al 2004c(Takakusaki et al , 2006.…”

“…It has been suggested that the BG-BS may also contribute to the modulation of vigilance states (Takakusaki et al, 2004c(Takakusaki et al, , 2005. Fundamental structures involved in the control of posture and locomotion and those in the muscle tone regulation during awake-sleep states exist in the brainstem and spinal cord (Chase & Morales 1990;Takakusaki et al, 1993Takakusaki et al, , 1994Takakusaki et al, , 2004aTakakusaki et al, , 2006. The importance of the midbrain area including the pedunculopontine tegmental nucleus (PPN) has been particularly recognized in relation to these functions (Palphill & Lozano 2000;Datta, 2002;Rye 1997).…”