Fear extinction is the learned inhibition of retrieval of previously acquired responses

This 2014 rodent study showed that fear extinction doesn’t depend on memory retrieval: “These results show that extinction and retrieval are separate processes and strongly suggest that extinction is triggered or gated by the conditioned stimulus even in the absence of retrieval.” The key to my understanding this finding came from a definition in another … Continue reading Fear extinction is the learned inhibition of retrieval of previously acquired responses

Hippocampal mechanisms involved in the enhancement of fear extinction caused by exposure to novelty

This 2014 Brazilian rodent study provided more information on the workings of the hippocampus. The researchers measured the effects of re-experiencing a fear within a specific context: “Within a restricted time window, a brief exposure to a novel environment enhances the extinction of contextual fear. The enhancement of extinction by the exposure to novelty depends … Continue reading Hippocampal mechanisms involved in the enhancement of fear extinction caused by exposure to novelty

An evolutionary view of transgenerational epigenetic inheritance

This 2020 Swiss/German review mainly cited weed, worm, and yeast studies: “RNA interference-related mechanisms can mediate the deposition and transgenerational inheritance of specific chromatin modifications in a truly epigenetic fashion. Epigenetics was initially defined as any heritable change in gene expression patterns without changes in the DNA sequence. Now, epigenetic phenomena are often characterized as … Continue reading An evolutionary view of transgenerational epigenetic inheritance

The role of recall neurons in traumatic memories

This 2018 Swiss rodent study found: “Our data show that: A subset of memory recall–induced neurons in the DG [dentate gyrus] becomes reactivated after memory attenuation, The degree of fear reduction positively correlates with this reactivation, and The continued activity of memory recall–induced neurons is critical for remote fear memory attenuation. Although other brain areas … Continue reading The role of recall neurons in traumatic memories

The role of DNMT3a in fear memories

This 2018 Chinese rodent study found: “Elevated Dnmt3a [a DNA methyltransferase] level in the dorsal dentate gyrus (dDG) of hippocampus was associated with the absence of fear renewal in an altered context after extinction training. Overexpression and knockdown of Dnmt3a in the dDG regulated the occurrence of fear renewal in a bi-directional manner. We found … Continue reading The role of DNMT3a in fear memories

The impact of the last snowflake

Was the recent Swiss avalanche’s cause the last, triggering snowflake, or the billions of snowflakes before it? There’s been a slight increase in the number of PNAS studies that included the “catastrophic” search word from October 2016 to mid-January 2018 compared to the January 2014 to mid-April 2015 period referenced in How well can catastrophes … Continue reading The impact of the last snowflake

What’s a good substitute for feeling loved?

A friend of mine sent a link to this TED talk yesterday. The speaker inspired my friend to change their life along the speaker’s guidelines: “The very act of doing the thing that scared me undid the fear. That feeling, you can’t help but strive for greatness at any cost. The more I work to … Continue reading What’s a good substitute for feeling loved?

What’s the underlying question for every brain study to answer?

Is the underlying question for every brain study to answer: How do our brains internally represent the external world? Is it: How did we learn what we know? How do we forget or disregard what we’ve learned? What keeps us from acquiring and learning newer or better information? How about: What affects how we pay … Continue reading What’s the underlying question for every brain study to answer?

Conclusions without evidence regarding emotional memories

The last sentence in the Significance section of this 2015 Emory/Harvard rodent study was: “These data highlight the potential to exploit sensory system plasticity as a means of ameliorating negative emotional memories that may be tied to peripheral sensory systems.” The “ameliorating negative emotional memories” part of this statement was incongruent with what the study … Continue reading Conclusions without evidence regarding emotional memories

Perpetuating the meme that rodent PTSD experiments necessarily apply to humans

This 2015 Texas A&M rodent study found: “Propranolol administration dampened the stress-induced impairment in extinction observed when extinction training is delivered shortly after fear conditioning.” The researchers were way off base in extrapolating this study to humans: “Propranolol may be a helpful adjunct to behavioral therapy for PTSD, particularly in patients who have recently experienced … Continue reading Perpetuating the meme that rodent PTSD experiments necessarily apply to humans

If rodent training had beneficial epigenetic effects, how can the next step be human gene therapy?

This 2014 rodent study detailed significant and lasting epigenetic DNA methylation in the hippocampus part of the limbic system as a result of fear-extinction training. The researchers missed the boat when explaining in interviews how their research could apply to humans. What I understood from the interviews was that the researchers were focused on targeting … Continue reading If rodent training had beneficial epigenetic effects, how can the next step be human gene therapy?

Is this science, or a PC agenda? Problematic research on childhood maltreatment and its effects

This 2013 Wisconsin human study’s goal was to assess effects of childhood trauma using both functional MRI scans and self-reported answers to a questionnaire. The families of the study’s subjects (64 18-year-olds) participated with researchers before some of the teenagers were born. How could the teenagers give answers that described events that may have taken … Continue reading Is this science, or a PC agenda? Problematic research on childhood maltreatment and its effects