How do mice react to vibrations? - briefly
Mice sense substrate vibrations via whisker and auditory receptors, prompting immediate orienting movements, startle, or escape responses. Higher frequency and amplitude vibrations produce stronger startle and freezing behaviors.
How do mice react to vibrations? - in detail
Mice detect vibratory cues through mechanoreceptors located in the whisker pads, skin, and inner ear. When a substrate vibrates, the whisker follicles transduce the motion into electrical signals that travel via the trigeminal pathway to the brainstem and somatosensory cortex. The auditory system also contributes, especially for frequencies above 1 kHz, where the cochlea converts pressure waves into neural activity.
Behavioral reactions depend on vibration characteristics:
- Low‑frequency (10–100 Hz) and low‑amplitude stimuli: mice often pause locomotion, orient their heads toward the source, and exhibit brief periods of immobility (freezing). This response is interpreted as an alert to potential predators or environmental disturbances.
- Mid‑frequency (100–500 Hz) with moderate intensity: rodents typically display exploratory whisking, increased sniffing, and rapid scanning movements, indicating assessment of the stimulus.
- High‑frequency (>500 Hz) and high‑amplitude bursts: mice may produce startle responses, including rapid whole‑body jerks, vocalizations, and escape attempts toward shelter.
Physiological measurements reveal:
- Somatosensory cortical activation: multi‑unit recordings show increased firing rates within the barrel cortex within 20–40 ms after stimulus onset.
- Auditory brainstem responses: click‑evoked potentials rise sharply for frequencies above 2 kHz, reflecting cochlear involvement.
- Autonomic changes: heart‑rate variability decreases during freezing, while respiratory rate accelerates during startle.
Neuromodulatory systems modulate these reactions. Elevated norepinephrine in the locus coeruleus enhances alertness, amplifying cortical responses to subtle vibrations. Conversely, increased GABAergic inhibition in the thalamus can suppress over‑reactivity, promoting a calm assessment state.
Experimental paradigms commonly employ:
- Piezoelectric actuators delivering controlled sinusoidal vibrations to a platform under the animal.
- High‑speed video tracking to quantify whisker displacement, head orientation, and locomotor speed.
- Electrophysiological probes inserted in the barrel cortex or inferior colliculus to correlate neural activity with behavioral phases.
Species and strain differences affect sensitivity. Laboratory strains such as C57BL/6 display lower detection thresholds (≈5 µm displacement) compared with wild‑derived mice, which may exhibit heightened startle thresholds due to ecological pressures.
In summary, vibratory input triggers a cascade from peripheral mechanoreceptors to central sensory circuits, producing a spectrum of motor and autonomic outputs that reflect the animal’s assessment of threat level, stimulus salience, and environmental context.