Pharmacological and deprivation-induced reinstatement of juvenile-like long-term potentiation in the primary auditory cortex of adult rats.

Sensory cortices show a decline in synaptic plasticity (e.g., long-term potentiation, LTP) during postnatal maturation.

NR2B subunit-dependent long-term potentiation enhancement in the rat cortical auditory system in vivo following masking of patterned auditory input by white noise exposure during early postnatal life.

The composition of N-methyl-D-aspartate (NMDA) receptor subunits influences the degree of synaptic plasticity expressed during development and into adulthood. Here, we show that theta-burst stimulation of the medial geniculate nucleus reliably induced NMDA receptor-dependent long-term potentiation (LTP) of field postsynaptic potentials recorded in the primary auditory cortex (A1) of urethane-anesthetized rats. Furthermore, substantially greater levels of LTP were elicited in juvenile animals (30-37 days old; approximately 55% maximal potentiation) than in adult animals (approximately 30% potentiation).

Decline of long-term potentiation (LTP) in the rat auditory cortex in vivo during postnatal life: involvement of NR2B subunits.

A decline in the ability of synapses to express plasticity and long-term potentiation (LTP) during postnatal maturation has been characterized in primary visual and somatosensory cortices. The present study is the first to document changes in the magnitude of LTP in the primary auditory cortex (A1) of rats at different stages of postnatal life. In urethane-anesthetized rats, field postsynaptic potentials (fPSPs) in A1 were elicited by stimulation of the medial geniculate nucleus, and LTP of cortical fPSPs was induced by application of repeated episodes of theta burst stimulation.

Continuous white noise exposure during and after auditory critical period differentially alters bidirectional thalamocortical plasticity in rat auditory cortex in vivo.

Long-term potentiation (LTP) and long-term depression are thought to mediate activity-dependent brain plasticity but their role in the development of the thalamocortical auditory system in vivo has not been investigated. In adult urethane-anaesthetized rats, theta-burst stimulation of the medial geniculate nucleus produced robust LTP (40% amplitude enhancement) of field post-synaptic evoked potentials recorded in the superficial layers of the primary auditory cortex. Low-frequency (1-Hz) stimulation resulted in transient depression ( approximately 40%) of field post-synaptic evoked potential amplitude.