Physiology and pathophysiology of cortico-basal ganglia–thalamocortical loops: Theoretical and practical aspects

Coordination between upper- and lower-limb movements is different during overground and treadmill walking

“…This indicates that when the stride frequency drops below the NPF of the upper limb by 20% or more, the arm-forearm segment stops swinging at the stride frequency and switches to a higher frequency, which, for the sake of the inter-limb synchrony, is exactly twice the frequency of the lower limb. Such a resetting phenomenon [which persists after changing the mass, and thus the NPF of the arm (Donker et al 2005;Webb et al 1994)] plays for a prominent role of central regulation of arm-leg coordination, which appears to operate by triggering changes in coupling mode (1:1 to 2:1) between integrated control systems (the upper and lower limb CPGs), whenever the discrepancy between a frequency-related controlled variable (the cadence) and a frequency-related mechanical parameter of a controlled object (the NPF of the upper limb, possibly stored as internal model) becomes greater than a criterion level (20% in our study) [see (Baev et al 2002)]. Application of the above concepts to the present results allows to postulate that during low speed TW, due to the greater cadence expressed compared to OW (41.1 stride/min versus 36.5; see Table 1), the discrepancy between cadence and NPF of the arm will fall below the criterion level, thereby reducing the probability of expression of a 2:1 coordination mode, and accounting for its lower occurrence rate (see Fig.…”

Passivity Phenomena: Implications for the Concept of Self

“…While limbic corticobasal ganglia-thalamocortical circuits select higher-level behavioral strategies (and while prefrontal circuits select goals), skeletomotor corticostriatal circuits implement these strategies by selecting lowerlevel motor acts in accordance with the environment. Baev et al (2002) conceptualized the interaction between limbic and skeletomotor circuits in terms of "neuronal optimal control systems." Optimal control systems are concerned with minimizing an externally imposed "initiating signal."…”

“…The skeletomotor system, in turn, is an optimal control system concerned with minimization of its own initiating signals, which are imposed upon it by the limbic system in the form of motivational states. Thus, motor behavior can be conceptualized as a means for the reduction of motivational signals emanating from the limbic system (after Baev et al, 2002).…”

A neuroanatomical model of passivity phenomena

“…While limbic cortico-basal ganglia-thalamocortical circuits select higher-level behavioural strategies, skeletomotor corticostriatal circuits implement these strategies by selecting lower-level motor acts in accordance with environmental stimuli. Baev et al (2002) conceptualised the interaction between limbic and skeletomotor circuits in terms of Ôneu-ronal optimal control systems.Õ Optimal control systems are concerned with minimising an initiating signal. For the system of limbic cortico-basal ganglia-thalamocortical circuits, initiating signals are given by basic physiological needs.…”

“…For this purpose, the limbic system imposes initiating signals in form of motivation onto the skeletomotor system. Thus, motor behaviour can be conceptualised as a means for the reduction of motivational signals emanating from the limbic system (after Baev et al, 2002).…”