Reversible Inactivation of Brain Circuits in Learning and Memory Research

Excerpt

The field of learning and memory has benefited from reversible brain interventions since they were introduced more than four decades ago., Progress in developing a variety of reversible inactivation procedures has led to a wide array of potent tools that now allow us to investigate different levels of learning and organization of brain memory processes. As noted in the literature, the complexity and variety of processes involved in learning and memory require a complex approach to advance the understanding of the relevant neurobiological mechanisms. Although much progress has been made at the molecular and cellular levels, a complete picture will be only attained by advancing knowledge of the functional organization of learning and memory brain circuits at the system level, which it is also recognized as the most difficult approach.

Limitations of the available techniques for undergoing a lesion approach in the field may contribute to the difficulties. This chapter will address the advantages and limitations of reversible inactivation techniques for research on the neural substrate of learning and memory at the system level. Thus, results of reversible manipulations aimed to explore the molecular mechanisms of learning and memory will not be considered because extensive reviews are available on specific topics.

Since the seminal work of Bures and Buresova inactivating wide brain regions to dissociate sensory and associative processes in taste aversion learning and also investigating interhemispheric transfer of memory traces, a range of procedures for temporary inactivation of discrete brain sites has been developed and applied to learning and memory research. Several reviews centering upon different learning procedures have been published in the past decade and show the value of the reversible inactivation approach for advancing knowledge in the field.,,, This chapter does not intend to be a comprehensive review of the knowledge gained using reversible inactivation approaches, but will show representative issues that have benefited from this approach, thus leading to a better knowledge of the brain organization of learning and memory processes at the system level. The need for careful interpretation of the behavioral results based on the specific brain changes induced by the currently available reversible inactivation techniques will be stressed.