Early uneven ear input induces long-lasting differences in left-right motor function

Area of Science:

• Neuroscience
• Motor Control
• Vestibular System

Background:

• Motor asymmetries in mammals can be experimentally induced via striatal dopamine manipulation.
• Factors causing motor asymmetry without direct brain intervention are largely unknown.

Purpose of the Study:

• Investigate the role of inner ear dysfunction in establishing motor asymmetries in mammals.
• Explore the neural mechanisms underlying inner ear-induced motor preferences.
• Determine if inner ear input influences brain lateralization and motor behavior.

Main Methods:

• Inducing inner ear dysfunction in mice to observe motor behavior.
• Utilizing extracellular signal-regulated kinase (ERK) antagonists to modulate striatal activity.
• Surgically inducing unilateral vestibular failure to control motor preference direction.
• Assessing handedness in humans in relation to vestibular input.

Main Results:

• Mice with inner ear dysfunction exhibit consistent left or right rotational preferences.
• This motor preference correlates with atypical asymmetry in cortico-striatal neurotransmission.
• Targeting striatal ERK activity can reverse or enhance motor preference.
• Direction of motor preference is dictated by the side of induced vestibular failure.
• In humans, the motor-dominant hemisphere is ipsilateral to the ear with weaker vestibular input.

Conclusions:

• Inner ear dysfunction is a significant factor in establishing motor asymmetry in mammals.
• Vestibular input can ontogenetically influence cortico-striatal asymmetries and left-right brain function.
• Inner ear-mediated pathways contribute to motor lateralization, impacting motor behavior and potentially handedness.