A time-limited role for hippocampal memory

The standard model of memory consolidation holds that over time, memories are transferred from the hippocampus to cortical areas. As a result, human patients with hippocampal lesions (e.g. the famous case of H.M.) have trouble recalling recent events, but no such problem with remote events. But there is an alternative: that the hippocampus is important for recalling vivid (presumably recent) but not vague (presumably remote) memories.

Using a novel experimental design that paired fMRI scans during verbal recall of autobiographical memories, this study could distinguish between these possibilities. The researchers found that although recent and remote memories had similar levels of detail and vividness, the hippocampus was more active for recent than remote memories. Their findings align with the standard model of memory consolidation, in which the hippocampus has a time-limited role in supporting memory recall.

Gilmore et al. (2021) Evidence supporting a time-limited hippocampal role in retrieving autobiographical memories. PNAS 118(12): e2023069118 DOI: https://doi.org/10.1073/pnas.2023069118

Teacher knowledge of working memory

Children with poor working memory (WM) are likely to struggle academically. As such, they could benefit from teachers who can recognize WM as the root cause of their learning difficulties, and implement strategies to address the problem.

In this study, over 1400 teachers completed a questionnaire that assessed their knowledge of WM. Most knew that WM was short-term memory used for processing a limited amount of information, and could identify signs of students with WM difficulties. However, only around two-thirds knew of strategies to help those students, and most teachers wrongly thought WM lasted minutes or hours, rather than a few seconds. The authors recommend that teacher training include more content on WM, and propose that researchers work with teachers to develop WM support materials.

Atkinson et al. (2021) Exploring the understanding and experience of working memory in teaching professionals: A large-sample questionnaire study. Teaching and Teacher Education 103: 103343 DOI: https://doi.org/10.1016/j.tate.2021.103343

A cognitive bias against improvement by subtraction

When trying to improve something – whether an idea, object or situation – we can add to, subtract from, or rearrange what already exists. Because the search space for these improvements is infinite, we often resort to mental shortcuts to find solutions.

This study reveals that our default approach is to look for improvements that add to the status quo, rather than those that subtract from what already exists. The authors point out that like many heuristics, this one might serve a purpose by being generally beneficial. However they also believe this cognitive bias might make us settle for adequate “additive” solutions, when a superior “subtractive” approach might exist. They also note that such a bias might be culture-dependent, with further studies needed to address this.

Adams et al. (2021) People systematically overlook subtractive changes. Nature 592: 258-261 DOI: https://doi.org/10.1038/s41586-021-03380-y

Inhibitory plasticity shapes oscillations and memory

Oscillations in the theta and gamma range are implicated in memory processes, meaning that disruptions to these brain rhythms could affect memory storage or retention. Here, researchers first show that a learning paradigm increases the strength of oscillations in the hippocampus. By genetically removing a key molecule from a subtype of inhibitory neuron, the researchers disrupt plasticity, prevent the increase in oscillation strength, and impair memory formation in mice. This reveals that the molecule, CaMKII, is required for plasticity from excitatory to inhibitory neurons in the hippocampus, in turn regulating oscillations and shaping long-term memory.

He et al. (2021) Gating of hippocampal rhythms and memory by synaptic plasticity in inhibitory interneurons. Neuron 109(6): P1013-1028.E9 DOI: https://doi.org/10.1016/j.neuron.2021.01.014