Memory is a critical function of the brain; we all remember, and in many ways our experiences and our memories of those experiences make us who we are. However, ‘memory’ is not a single entity – it is neither a single process, nor dependent upon any one structure in the brain. Memories can be studied in many different ways, and at many different levels of analysis. This course will examine memory at multiple levels, from the molecular biological to the psychological.
Memories can be distinguished by their temporal properties, by their function, and by the sort of information that each memory holds. This course will begin by examining the different types of memory, from the rapidly decaying sensory memory that gives us a coherent percept of the world, to long-term memories that can last for a lifetime. The case of the amnesic patient HM, and how Milner’s work with him revolutionised the way in which long-term memory was conceptualised, will be considered in detail, along with other studies that inform our understanding of the ‘taxonomy’ of long-term memory.
The storage of information is clearly important for memory to function, but storing information is useless if that information cannot be retrieved. The interaction between working and long-term memory will be considered, along with the brain networks that mediate and underlie conscious retrieval. We will also examine what causes us to forget – from simple instances of retrieval failure to the complex inhibitory processes that allow us to direct our forgetting, and which may confer resilience against psychiatric disorders characterised by traumatic memories.
Having examined retrieval, we will then discuss the processes that underlie memory encoding and persistence. We will consider how a short-term memory becomes ‘consolidated’ into a long-term form at the cellular level, and link this to the physiological process of ‘long-term potentiation’. We will interrogate the dominant theory of memory in neuroscience, the ‘synaptic plasticity and memory’ hypothesis, by examining whether long-term potentiation is both necessary and sufficient to explain the persistence of memory. We will also consider how to address some of the theoretical issues raised by HM’s amnesia – including, for instance, how he could still remember the layout of his parent’s house when he was incapable of forming new memories. Two rival theories dominate this contentious field, and we will examine both the ‘systems-level consolidation’ view and the ‘multiple trace theory’, and consider how to relate both of these to cellular-level consolidation.
Theories of consolidation imply that, once formed, memories are immutable in their content. This has been a long-held view in neuroscience, despite abundant psychological evidence that memory is reconstructive and often rather inaccurate. We will reconcile these two views by exploring the process of memory reconsolidation; initially controversial, this process has become increasingly accepted as the mechanism by which memories can be updated with new information at retrieval. We will consider whether reconsolidation is simply a recapitulation of consolidation, in molecular and neurobiological terms. We will also discuss whether reconsolidation occurs for all types of memories, and how it might relate to the generalisation of memories, the production of ‘false memories’, and the systems-level consolidation described previously.
Finally, having explored memory in many different ways, we will consider the practical applications of memory research – from enhancing the accuracy of eyewitness testimony, to treating psychiatric disorders such as post-traumatic stress disorder and drug addiction.
