Prefrontal - Hippocampal Interaction: An Integrative Review and Model of the Think/No-Think Task with Implications for Psychiatric Conditions

Abstract

Being able to dynamically control accessibility to memories enables humans to flexibly adapt to their environment. When this control fails we become acutely aware of emotionally painful reminders of past events. Individuals suffering from some psychiatric conditions are plagued by intrusive, uncontrollable thoughts and ruminations of such memories. To gain a better understanding of this pathos, it is first essential to investigate the neural pathways that allow for control over memory accessibility in the non-psychiatric brain. To do so, a review of the neuroimaging Think/ No-Think literature is used to provide possible brain regions that contribute to the control over memory accessibility. Using these results combined with literature from comparative anatomy/neurology, a neuroanatomical model is derived that provides more specific neural detail than currently in the literature. This model highlights the importance of PFC -hippocampal interaction and the possible mechanisms by which control over memory accessibility is achieved. By understanding these details, future directions for targeting research on psychiatric conditions will hopefully be achieved.

Emotions shape memory suppression in trait anxiety

“…These results, although taken cautiously, might have some implications for disorders in which ruminative thought and negative memories are dysfunctional, such as anxiety, depression, OCD, acute stress disorder (ASD; Aldao et al, 2010; Depue, 2011). …”

“…Our findings may be viewed as showing that deliberate avoidance of thoughts associated with an emotionally negative experience may lead to loss of memory ( Lambert et al, 2010 ) but that this effect is disrupted when the executive control functions are not so efficient, as is the case in anxiety ( Eysenck and Derakshan, 2011 ). These results, although taken cautiously, might have some implications for disorders in which ruminative thought and negative memories are dysfunctional, such as anxiety, depression, OCD, acute stress disorder (ASD; Aldao et al, 2010 ; Depue, 2011 ).…”

“…The existence of this attempt to control memory has been demonstrated behaviorally and more recently also by means of neuroimaging and electrophysiological studies (for a review see Depue, 2011, 2012). These studies suggest that memory suppression occurs through cognitive inhibitory control as demonstrated by an increased activation of the prefrontal cortex which down-regulates the hippocampal regions.…”

“…The core mechanisms underlying memory suppression are executive control processes that are engaged to control and inhibit the influence of unwanted memories by rendering retrieval more difficult ( Anderson and Green, 2001 ; Levy and Anderson, 2008 ). The existence of this attempt to control memory has been demonstrated behaviorally and more recently also by means of neuroimaging and electrophysiological studies (for a review see Depue, 2011 , 2012 ). These studies suggest that memory suppression occurs through cognitive inhibitory control as demonstrated by an increased activation of the prefrontal cortex which down-regulates the hippocampal regions.…”