Monday, July 23, 2007

Emotional visual memories

Research at the University of Colorado in Boulder indicates that emotional visual memories can be suppressed.

About two decades ago here in northern California we had a few high-profile trials involving persons with a sudden recall of sexual abuse during childhood. A researcher who subsequently showed how false memories can be created, had her life threatened and was persecuted — an indication of how controversial research on the manipulation of memories is.

I do not remember the details, but at that time research indicated how visual memories are not cast in concrete in the form of fixed synaptic connections. Instead, visual memories are constantly relived or revisited, e.g., in the slow wave phase of sleep. A recall entails reliving the memory, i.e., retrieval of memories entails the same regions in the brain that are involved in encoding a memory. False memories can be created by repeatedly inserting false images during this recall process.

The new research at the University of Colorado in Boulder unveils how emotional visual memories can be suppressed via two time-differentiated neural mechanisms:

  1. an initial suppression by the right inferior frontal gyrus over regions supporting sensory components of the memory representation (visual cortex, thalamus), followed by
  2. right medial frontal gyrus control over regions supporting multimodal and emotional components of the memory representation (hippocampus, amygdala), both of which are influenced by fronto-polar regions.

A paper on this research has been published in Science 13 July 2007.

According to the researchers, their findings may have implications for therapeutic approaches to disorders involving the inability to suppress emotionally distressing memories and thoughts, including PTSD (posttraumatic stress disorder), phobias, ruminative depression/anxiety, and OCD (obsessive-compulsive disorder). They provide the possibility for approaches to controlling memories by suppressing sensory aspects of memory and/or by strengthening cognitive control over memory and emotional processes through repeated practice. Refinement of therapeutic procedures based on these distinct means of manipulating emotional memory might be an exciting and fruitful development in future clinical research.