Hippocampus

Making lasting memories: Remembering the significant

gettingwell4 4-5 stars Advanced knowledge, Amygdala, Cerebrum, Hippocampus, Limbic system, Memory, Stress

This 2013 article summarized 158 studies related to the roles of regions in the limbic system and memory:

“Episodic memory is the capacity to recall specific experiences and to re-experience individual events.

The findings of both animal and human studies provide compelling evidence that stress-induced activation of the amygdala and its interactions with other brain regions involved in processing memory play a critical role in ensuring that emotionally significant experiences are well-remembered.”

http://www.pnas.org/content/110/Supplement_2/10402.full “Making lasting memories: Remembering the significant”

Our memories have contexts with specific places and times

gettingwell4 5+ stars Premium, Hippocampus, Limbic system, Memory

This 2014 rodent study was of the place aspect of a memory’s context. The researchers found that the CA3 segment of the hippocampus stored a unique representation of the location where the memory was formed:

“Place cells are hippocampal cells (in CA3) that fire specifically when the animal is at a certain location.

Form unique representations for every single environment.

When the animal was introduced to one of the rooms a second time the spatial map from the first exposure was reactivated.”

Our memories are formed within a specific context tied in the time aspect of a memory’s context:

“Hippocampal neurons not only track time, but do so only when specific contextual information (e.g., object identity/location) is cued.”

Our memories have contexts with specific places and times. Accessing a memory’s specific context would be a necessary part of accessing a full memory.

http://www.pnas.org/content/111/52/18428.full “Place cells in the hippocampus: Eleven maps for eleven rooms”

Our memories are formed within a specific context

gettingwell4 4-5 stars Advanced knowledge, Hippocampus, Limbic system, Memory

This 2014 primate study provided evidence that our memories are formed within a specific context:

“The hippocampus, a structure known to be essential to form episodic memories, possesses neurons that explicitly mark moments in time.

We add a previously unidentified finding to this work by showing that individual primate hippocampal neurons not only track time, but do so only when specific contextual information (e.g., object identity/location) is cued.”

As the study may apply to humans, it would follow that accessing a memory’s specific context would be a necessary part of accessing a full memory.

http://www.pnas.org/content/111/51/18351.full “Context-dependent incremental timing cells in the primate hippocampus”

Sorry to disable comments, but this post has somehow become a spam target. Readers can comment on Our memories have contexts with specific places and times which incorporates this study’s findings.

Conscious mental states should not be the first-choice explanation of behavior

gettingwell4 4-5 stars Advanced knowledge, Amygdala, Cerebrum, Hippocampus, Limbic system, Memory , ,

Here are some 2014 ruminations by Joseph LeDoux, the grandfather of studies of the amygdala. He attempted to disambiguate feeling brain structures’ activations and responses from ideas of what feelings are, specifically regarding fear:

“Damage to the hippocampus in humans disrupts explicit conscious memory of having been conditioned but has no effect on fear conditioning itself, whereas damage to the amygdala disrupts fear conditioning but not the conscious memory of having been conditioned.

Conscious mental states should not, in the absence of direct evidence, be the first-choice explanation of behavior.

Neither amygdala activity nor amygdala-controlled responses are telltale signatures of fearful feelings.

Conscious fear can cause us to act in certain ways, but it is not the cause of the expression of defensive behaviors and physiological responses elicited by conditioned or unconditioned threats.”

http://www.pnas.org/content/111/8/2871.full “Coming to terms with fear”