Proprioceptive feedback in locust kicking and jumping during maturation

Area of Science:

• Neuroethology
• Biomechanics
• Insect Physiology

Background:

• Campaniform sensilla are mechanoreceptors that detect forces on insect exoskeletons.
• These sensilla play a role in motor control by providing sensory feedback to the nervous system.
• Locust leg muscle activity, particularly during co-contraction for jumping, is influenced by sensory input.

Purpose of the Study:

• To investigate the role of campaniform sensilla in locust leg motor control during development.
• To compare the sensory feedback from campaniform sensilla between immature and mature locusts.
• To understand how developmental changes in sensory feedback affect motor behavior like kicking and jumping.

Main Methods:

• Comparison of campaniform sensillum activity in newly moulted (immature) versus mature locusts (Schistocerca gregaria).
• Electrophysiological recordings of sensory neurons and motor neurons (fast extensor tibiae - FETi, flexor tibiae).
• Stimulation of the extensor tibiae muscle to mimic co-contraction activity patterns.

Main Results:

• Immature locusts generated less force and exhibited lower sensory neuron spike frequency compared to mature locusts.
• Sensory feedback resulted in less depolarization of motor neurons in immature locusts.
• Differences in depolarization suggest modulation of central connections of sensory afferents during development.

Conclusions:

• Feedback from anterior campaniform sensilla significantly contributes to motor drive for leg co-contraction in mature locusts.
• Developmental changes in this sensory feedback are critical for the maturation of kicking and jumping behaviors.
• Modulation of central connections is a key factor in the developmental plasticity of motor control.