What roles do tonic inhibition and disinhibition play in the control of motor programs?

Benjamin Benjamin

doi:10.3389/fnbeh.2010.00030

Abstract

Animals show periods of quiescence interspersed with periods of motor activity. In a number of invertebrate and vertebrate systems, quiescence is achieved by active suppression of motor behavior is due to tonic inhibition induced by sensory input or changes in internal state. Removal of this inhibition (disinhibition) has the converse effect tending to increase the level of motor activity. We show that tonic inhibition and disinhibition can have a variety of roles. It can simply switch off specific unwanted motor behaviors, or modulate the occurrence of a motor response, a type of ‘threshold’ controlling function, or be involved in the selection of a particular motor program by inhibiting ‘competing’ motor mechanisms that would otherwise interfere with the carrying out of a desired movement. A suggested general function for tonic inhibition is to prevent unnecessary non-goal directed motor activity that would be energetically expensive. The reason why basic motor programs might be a particular target for tonic inhibition is that many of them involve central pattern generator circuits that are often spontaneously active and need to be actively suppressed for energy saving. Based on this hypothesis, tonic inhibition represents the default state for energy saving and motor programs are switched-on when required by removal of this inhibition.

Highlights

There are many examples in the neuroethological literature where animals show periods of reduced motor activity or quiescence and this makes evolutionary sense because it reduces unnecessary energy expenditure and potentially makes animals less conspicuous to predators (Lambert et al, 2004a)
In a number of systems this reduction of motor activity is due to tonic inhibition of motor circuits induced by sensory inputs or changes in internal state
Tonic inhibition has the potential to both suppress and activate motor behavior depending on the level of electrical firing in the inhibitory pathways, acting as a type of neural switching mechanism

Summary

BEHAVIORAL NEUROSCIENCE

What roles do tonic inhibition and disinhibition play in the control of motor programs?. In a number of invertebrate and vertebrate systems, quiescence is achieved by active suppression of motor behavior is due to tonic inhibition induced by sensory input or changes in internal state. A suggested general function for tonic inhibition is to prevent unnecessary non-goal directed motor activity that would be energetically expensive.The reason why basic motor programs might be a particular target for tonic inhibition is that many of them involve central pattern generator circuits that are often spontaneously active and need to be actively suppressed for energy saving. Based on this hypothesis, tonic inhibition represents the default state for energy saving and motor programs are switched-on when required by removal of this inhibition

Background

Tonic inhibition of motor programs

Findings

Conclusions and discussion