Neonatal whisker clipping alters behavior, neuronal structure and neural activity in adult rats.

Early experience plays critical roles during the development of sensory systems. For example, neonatal surgical manipulations of the whiskers in rodents lead to altered neural activity and behaviors later in life. However, while surgical procedures damage the sensory pathway; it is hard to examine the impact of whisker deprivation on adult animals. To address this issue, we performed a neonatal whisker clipping (WC0-3) paradigm, a non-invasive procedure, from the day of birth (P0) to postnatal day (P) 3, and examined behavioral performances in their adult age. With fully regrown whiskers, the WC0-3 rats exhibited shorter crossable distance than controls in a gap-crossing task, suggesting a defect in their whisker-specific tactile function. In their somatosensory cortex, the layer IV spiny stellate neurons had reduced dendritic complexity and spine density. After exploration in a novel environment, the expression of an activity-dependent immediate early gene, c-fos, increased dramatically in the somatosensory cortex. However, in WC0-3 rats, the number of c-Fos positive cells was less than those in control rats, indicating a fault in transducing sensory-related neural activity between cortical layers in WC0-3 rats. Together, our results demonstrate the roles of early tactile experience on the establishment of layer-specific excitatory connection in the barrel cortex. Early sensory insufficiency would leave long-lasting functional deficits in the sensory system.

Chu YF ，Yen CT ，Lee LJ 《-》

Neonatal whisker trimming causes long-lasting changes in structure and function of the somatosensory system.

Lee LJ ，Chen WJ ，Chuang YW ，Wang YC ... -  《-》

Whisker trimming begun at birth or on postnatal day 12 affects excitatory and inhibitory receptive fields of layer IV barrel neurons.

Shoykhet M ，Land PW ，Simons DJ 《JOURNAL OF NEUROPHYSIOLOGY》

Tactile sensory input regulates basal and apomorphine-induced immediate-early gene expression in rat barrel cortex.

Steiner H ，Gerfen CR 《-》

Effects of vibrissae removal on methamphetamine-induced damage to rat somatosensory cortical neurons.

Repeated methamphetamine (mAMPH) damages forebrain monoamine terminals and causes degeneration of nonmonoaminergic cell bodies in rat primary somatosensory cortex (S1). These degenerating cortical neurons can be labeled with the fluorochrome dye Fluoro-Jade (FJ) and are found almost exclusively in layers II/III and IV of the vibrissae representation in S1. Within S1, layer IV is organized into discrete, anatomically identifiable units termed barrels, each of which receives information from a single whisker. We previously reported that mAMPH-damaged neurons in S1 were located within the whisker barrels, suggesting that the prolonged mAMPH-induced whisking contributes to S1 neuronal injury. Here, we investigate effects of vibrissae removal on mAMPH-induced damage to S1 neurons. Rats were anesthetized and vibrissae were trimmed from either the left, right, or neither side of the snout. The next day they were given four injections of either saline (1 ml/kg, s.c.) or mAMPH (4 mg/kg, s.c.) at 2-h intervals. Three days later, cortical sections were processed for FJ histochemistry. The hemivibrissotomy produces a hemispheric asymmetry in FJ-positive neurons in barrel cortex, with fewer damaged neurons contralateral than ipsilateral to whisker removal. Taken together with the demonstration that acute injection of this dose of mAMPH induces the immediate early gene zif/268 and Fos protein in barrel cortex, these data suggest that the prolonged behavioral activity involving the vibrissae contributes to the mAMPH-induced damage to S1 neurons. Thus, some of the injurious effects of drugs may depend on afferent activity occurring as a result of the abnormal behaviors evoked by their administration.

O'Dell SJ ，Marshall JF 《-》