Han Zhang, MD

Biography

Neural Mechanisms Underlying Learning And Memory

The focus of my laboratory is into the neural mechanisms underlying learning and memory.

Specifically, my research attempts to link morphological changes with the enhancement of synaptic efficacy, such as long-term facilitation, a well-established synaptic model for memory. The marine mollusc Aplysia californica is used as a model system to investigate the morphological correlates of the sensory and motor neurons involved in the tail-withdrawal reflex.

Several of our experiments have shown that morphological changes are correlated with synaptic strength. For example, with intracellular dye injections into pairs of physiologically-connected sensory and motor neurons of the tail-withdrawal reflex, we have found that the number of sensory-motor contacts were proportional to the strength of the physiological connection. Currently, we are using two-photon confocal microscopy to investigate the outgrowth and synaptic contacts of living sensory neurons under different experimental conditions.

Additionally, there is increasing evidence suggesting that the neurotransmitter serotonin plays an important role in sensitization. Using intracellular injection, immunofluorescence, and confocal microscopy imaging techniques, we have shown that serotonergic neurons make contacts with both sensory and motor neurons. Most of these contacts are relatively distant from the sensory-motor contacts, and with the use of electron microscopy, we will investigate the ultrastructure of these contacts.

Although research is my main focus, I contribute to the academic goals of the department’s anatomical program as well. Currently, I am designing and building an anatomy museum, in addition to multiple anatomical specimens. These developments are significant in the continuous effort to improve teaching and anatomy laboratories for medical students.