Posts Tagged ‘infantile amnesia’

31st Meeting of the Association for Psychological Science Pt. 2

June 3, 2019

A definite highlight of the meeting was lecture by Lynn Nadel titled, Taking James Seriously: The Implications of Multiple Memory Systems. The James referred to in the title is William James, the father of American Psychology. James wrote about multiple memory systems, a primary and a secondary memory, which today are referred to as short term and long term memory. He made a distinction between habits and memory.

James passed away long before the emergence of neuroscience. The hippocampus plays an important role in the processing of memories. There was a famous epileptic patient referred to as HM who had large portions of his temporal lobes removed. A hippocampus is located in each one of those lobes. Although his previous memories remained intact, not only each new day, but each new hour was a new experience for HM. And these experiences would not be remembered.

There is a distinction between episodic memory, which holds the memories of our daily experiences is processed in the hippocampus, and semantic memory, which holds our general knowledge of the world, is resident in our neocortex.

The hippocampus is also critical to navigation. The neuroscientist O’Keefe identified place cells in the hippocampus. These place cells identify spatial locations where the organism travels. Learning to navigate entails strengthening these place cells and learning to follow them to desired locations.

In most species, the hippocampus matures postnatally. This has important consequences for memory and cognitive development. Dr. Nadel asks what does it mean to start life with a developing, but not yet functioning hippocampus, perhaps uniquely susceptible to impacts of experience early in life. In humans it takes 18-24 months for the hippocampus to emerge, and it takes 10-12 years for it to become fully functional.

Dr. Nadel speculates that phobias can develop before the hippocampus emerges. This late emergence of the hippocampus explains infantile amnesia and delayed exploration and place learning. Everything we learn very early in life is context free. The individual has no understanding of why she has certain fears, as the cause of the fear was not stored in memory. As for the 10-12 years for the hippocampus, an extremely important structure, to become fully functional, it might result in shortcomings in learning and interpersonal interactions.