Dept Home Page > Department Faculty > Han Zhang, M.D.

Han Zhang, M.D.

Senior Lecturer

Telephone: 713.500.5628
E-mail: han.zhang@uth.tmc.edu

Neural Mechanisms Underlying Learning and Memory

Confocal microscopy imaging show the contacts among SN (red), motor (green) and serotonergic neurons (blue) in pedal ganglion.

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.

Selected Reading

Zhang H, Wainwright M, Byrne JH, Cleary LJ. (2003) Quantitation of contacts among sensory, motor, and serotonergic neurons in the pedal ganglion of aplysia. Learn Mem. 2003 Sep-Oct;10(5):387-93.

Goktepe AS, Chiou-Tan FY, Zhang H, Taber KH. (2004) Sectional neuroanatomy of the face. J Comput Assist Tomogr. 2004 Nov-Dec;28(6):865-9.

Chiou-Tan FY, Miller JS, Goktepe AS, Zhang H, Taber KH. (2005) Sectional neuroanatomy of the upper thoracic spine and chest. J Comput Assist Tomogr. 2005 Mar-Apr;29(2):281-5. Review. Erratum in: J Comput Assist Tomogr. 2005 Jul-Aug;29(4):569.

Miller JS, Goktepe AS, Chiou-Tan F, Zhang H, Taber KH. (2006) Sectional neuroanatomy of the middle thoracic spine (t5-t8) and chest. J Comput Assist Tomogr. 2006 Jan-Feb;30(1):161-4.

Search PubMed for additional articles.