Activity Of Single Neuron In The Dentate Gyrus Of Guinea Pig During The Consolidation Of Trace Eyeblink Conditioning

Aims and methods:Experimental and clinical investigations have implicated the hippocampus as having important functions in learning and memory. A number of hippocampally dependent behavioral paradigms have been developed to examine the neural mechanisms of learning and memory. The classical eyeblink conditioning is one of these paradigms. The establishment of classical eyeblink conditioning paradigm depends on repeated pairings of a conditioned stimulus (CS, usually a tone) and an unconditioned stimulus (US, usually a corneal airpuff). There are two paradigms of eyeblink conditioning that differ in the temporal relationship between the CS and US. In the delay paradigm, the CS precedes, overlaps, and coterminates with the US. On the other hand, in the trace paradigm, the CS and the US are separated by a stimulus-free trace interval. A large number of lesion studies indicate that the hippocampus plays a critical role during the consolidation of trace eyeblink conditioning; however, the role of its related structure such as dentate gyrus (DG) remains unclear.It is well known that, within the hippocampal formation, the neuronal information is communicated along a chain of neurons, beginning with the axons of granule cells of the DG. Their mossy fibers impinge on the neighboring dendrites of CA3 neurons, which project their axons to the CA1 region. It is meaningful to explore the role of the DG during the consolidation of trace eyeblink conditioning, which will be helpful to reveal the neural mechanisms of learning and memory.The present study were divided into two parts: Firstly, to record the spontaneous discharging signals in the DG of waking guinea pigs, and to explore the spontaneous discharging characteristics of the DG neurons; Secondly, to establish the trace eyeblink conditioning, and to observe the activity of single DG neuron during the consolidation of trace eyeblink conditioning, which allowed us to determine whether the DG involved in the neural circuit important for the consolidation of trace eyeblink conditioning.