Whisker plucking alters responses of rat trigeminal ganglion neurons

Abstract

Whisker plucking in developing and adult rats provides a convenient method of temporarily altering tactile input for the purposes of studying experience-dependent plasticity in the somatosensory cortex. Yet, a comprehensive examination of the effect of whisker plucking on the response properties of whisker follicle-innervating trigeminal ganglion (NVg) neurons is lacking. We used extracellular single unit recordings to examine responses of NVg neurons to controlled whisker stimuli in three groups of animals: (1) rats whose whiskers were plucked from birth for 21 days; (2) rats whose whiskers were plucked once at 21 days of age; and (3) control animals. After at least 3 weeks of whisker regrowth, NVg neurons in plucked rats displayed normal, single whisker receptive fields and could be characterized as slowly (SA) or rapidly adapting (RA). The proportion of SA and RA neurons was unaffected by whisker plucking. Both SA and RA NVg neurons in plucked rats displayed normal response latencies and angular tuning but abnormally large responses to whisker movement onsets and offsets. SA neurons were affected to a greater extent than RA neurons. The effect of whisker plucking was more pronounced in animals whose whiskers were plucked repeatedly during development than in rats whose whiskers were plucked once. Individual neurons in plucked animals displayed abnormal periods of prolonged rhythmic firing following deflection onsets and aberrant bursts of activity during the plateau phase of the stimulus. These results indicate that whisker plucking exerts a long-term effect on responses of trigeminal ganglion neurons to peripheral stimulation.

Effects of arousal and movement on secondary somatosensory and visual thalamus

“…To measure the degree to which POm activity is driven by the sensory reafference caused by whisking, we severed the buccal and upper marginal branches of the facial motor nerve on the right side of the face, contralateral to our recordings while taking video of the left (ipsilateral) side of the face ( Figure 2A ). This manipulation does not damage the sensory neurons and avoids the risk of inducing sensory neuron plasticity ( Shetty et al, 2003 ). Mice were no longer able to move the right whisker pad but whisking on the left side of the face was unaffected ( Figure 2B and C ).…”

Responses of Trigeminal Ganglion Neurons during Natural Whisking Behaviors in the Awake Rat

“…At the end of recording sessions, rats were anesthetized and each whisker was stimulated to identify the cell's principle whisker (PW) and preferred direction (Shoykhet et al, 2000;Shetty et al, 2003;Leiser and Moxon, 2006). Cells were rediscriminated after each recording.…”

Whisker growth in Tasmanian devils (Sarcophilus harrisii) and applications for stable isotope studies

“…Plucking a whisker a single time does not affect the growth of a new whisker; however, there may be a delay before the new whisker appears above the skin surface if the previous whisker was still growing (Ibrahim and Wright 1978). Shetty et al (2003) found that repeated v www.esajournals.org plucking of rat whiskers from the same follicle over a short period (every 2-3 d over 21 d) damaged the follicle and altered sensory input generated by the neurons. Frequent cutting of hair close to the skin has varied impacts on subsequent growth (Seymour 1926, Kim et al 1962).…”