Effects Of Auditory Deprivation On Developmental Changes In Intrinsic Properties And Synaptic Function Of Neurons In Rat Primary Auditory Cortex

In the visual and somatosensory system, early sensory experience plays a crucial role in the refinement of developing thalamocortical circuits. Experience-dependent modifications at afferent cortical inputs typically only occur during a postnatal"critical period,"after which synaptic reorganization is difficult to induce. NMDA receptor (NMDAR) is generally believed to play a critical role in the development of central synapses. NMDAR-mediated long-term potentiation (LTP) has been proposed to reflect the recruitment of AMPA receptor (AMPAR) to synapses that previously contained only NMDAR (silent synapses). While these developmental changes in glutamatergic transmission and critical periods for experience-dependent plasticity have been well characterized in the visual and somatosensory systems, factors shaping the maturation of auditory cortical sensory synapses are less clear.Hearing is a critical sensory modality; however, little is known about the developmental maturation of synaptic transmission at afferent cortical synapses in the auditory system and the consequences of early auditory experience in the auditory nerve center. Furthermore, it is unknown why central auditory circuits display high plasticity during early postnatal development.Layer 3/4(L3/4) neuron in primary auditory cortex (Aâ… ) receive primary excitatory input from auditory thalamus. Within Aâ… , integration of sensory inputs in L3/4 neurons is a key step underlying the discrimination and perception of auditory information in the brain. In view of intrinsic membrane properties and synaptic connection as two key mechanisms controlling the integration of sensory inputs information of any given neuron, and the crucial role of dendrites in neuron electrotonic properties and number of input synapses, here we explore the development of intrinsic membrane properties, synaptic function and morphology of L3/4 neurons in Aâ… , and further the effects of early auditory deprivation (AD) on them. Auditory thalamocortical brain slice were made of 5- to 28-day-old normal hearing rats and AD rats whose bilateral cochleae had been ablated at postnatal 4-6 day. After acquirement of whole-cell recording of Aâ… L3/4 neurons in patch clamp, several...