Models of brain injury and alterations in synaptic plasticity

Animal models are crucial for understanding human pathophysiological processes and for understanding how connections are injured, lost, or even regenerated and/or repaired. When animal models are used in conjunction with theoretical computational models, an ideal combination is achieved that potentially yields insight and encourages the formation of new theories concerning connectionism, cognitive functioning, and synaptic mechanisms. Mechanisms regulating glutamate receptor activation and intracellular calcium levels are important for normal synaptic transmission. These mechanisms (and others) are also critical during and after brain injury when the potential exists for these mechanisms to function pathologically. Interestingly enough, the regulation of glutamate receptor activation and intracellular calcium levels is also involved in normal processes of neuronal and synaptic plasticity. In addition, studies have shown that neurotrophins and cytokines, which are released after brain injury, can be neuroprotective and may also be important in synaptic plasticity. Furthermore, synaptic plasticity is a phenomenon thought by many to be necessary for memory encoding. If this is the case, then research described in this review has significant scientific merit concerning plasticity and memory and clinical benefit for understanding pathophysiologic processes associated with brain injury and memory impairment. This paper reviews the application of experimental animal models of brain injury for simulating conditions of stroke, trauma, and epilepsy (and/or seizure generation) and the associated cellular mechanisms of brain injury. The paper also briefly addresses the advantage of using computational models in combination with experimental models for hypothesis building and for aiding in the interpretation of empirical data. Finally, it reviews studies concerning brain injury and synaptic plasticity.