Brain-Generated 17β-Estradiol Modulates Long-Term Synaptic Plasticity in the Primary Auditory Cortex of Adult Male Rats.

Neuron-derived 17β-estradiol (E2) alters synaptic transmission and plasticity in brain regions with endocrine and non-endocrine functions. Investigations into a modulatory role of E2 in synaptic activity and plasticity have mainly focused on the rodent hippocampal formation. In songbirds, E2 is synthesized by auditory forebrain neurons and promotes auditory signal processing and memory for salient acoustic stimuli; however, the modulatory effects of E2 on memory-related synaptic plasticity mechanisms have not been directly examined in the auditory forebrain.

Is hippocampal theta frequency related to individual and sex differences in anxiety-like behaviour? An analysis in male and female Long-Evans rats.

Hippocampal theta activity is a prominent slow (4-12 Hz) oscillatory activity pattern generated in the mammalian hippocampal formation. Based on evidence that anxiolytic drugs consistently decrease the frequency of hippocampal theta activity in rodents, hippocampal theta has been linked to anxiety states, leading to the influential theta suppression model of anxiolysis. Surprisingly, very few studies have examined whether hippocampal theta frequency relates to individual or sex differences in anxiety-like behaviour.

Gating of long-term potentiation (LTP) in the thalamocortical auditory system of rats by serotonergic (5-HT) receptors.

The neuromodulator serotonin (5-hydroxytryptamine, 5-HT) plays an important role in controlling the induction threshold and maintenance of long-term potentiation (LTP) in the visual cortex and hippocampus of rodents. Serotonergic fibers also innervate the rodent primary auditory cortex (A1), but the regulation of A1 plasticity by 5-HT receptors (5-HTRs) is largely uncharted. Thus, we examined the role of several, predominant 5-HT receptor classes (5-HTRs, 5-HTRs, and 5-HTRs) in gating in vivo LTP induction at A1 synapses of adult, urethane-anesthetized rats.

Effects of Patterned Sound Deprivation on Short- and Long-Term Plasticity in the Rat Thalamocortical Auditory System In Vivo.

Postnatal sensory experience plays a significant role in the maturation and synaptic stabilization of sensory cortices, such as the primary auditory cortex (A1). Here, we examined the effects of patterned sound deprivation (by rearing in continuous white noise, WN) during early postnatal life on short- and long-term plasticity of adult male rats using an in vivo preparation (urethane anesthesia). Relative to age-matched control animals reared under unaltered sound conditions, rats raised in WN (from postnatal day 5 to 50-60) showed greater levels of long-term potentiation (LTP) of field potentials in A1 induced by theta-burst stimulation (TBS) of the medial geniculate nucleus (MGN).