Is rating pre-service teachers by observation fair?
As part of their training, pre-service teachers (PSTs) undergo “clinical placements” in which they teach in schools under the guidance of a trained observer. The PST receives feedback from the observer, helping their development as a teacher.
The success of this process relies on observer evaluations accurately reflecting PST quality. However in this study of 2100 PSTs, the biggest factor impacting PST evaluation scores was the trained observer, rather than the quality of the PST. There were also small but systematic biases in evaluations, for example females rated more highly than males, and whites more highly than non-whites. Because these observer-dependent evaluation scores had direct consequences for the PST’s employment, the authors suggest rating reliability could be increased by using a standardised scale for PST observers, or by using multiple observers.
Bartanen and Kwok (2021) Examining clinical teaching observation scores as a measure of preservice teacher quality. American Educational Research Journal 58(5): 887-920 DOI: https://doi.org/10.3102/0002831221990359
Stabilizing dendritic spines enhances motor learning
Motor learning is an essential skill that allows us to interact with and manipulate our environment. In this study, researchers show that mice lacking a particular gene can learn a motor task more quickly than their wildtype colleagues. The authors traced this ability to subtle changes in individual motor neurons: the new dendritic spines produced during the learning process were larger and more stable in the knockout mice, and this directly contributed to better learning. Enhanced learning did not require genetic alteration, as it could also be achieved pharmacologically in wildtype mice.
Albarran et al. (2021) Enhancing motor learning by increasing the stability of newly formed dendritic spines in the motor cortex. Neuron DOI: https://doi.org/10.1016/j.neuron.2021.07.030
Arousal maintains the vividness of memories
After they are formed, autobiographical memories are consolidated, moving them from short-term to long-term storage. This process, some of which happens during sleep, involves a transition from dependence on the hippocampus (short-term memory) to a greater role for the cortex (long-term), and a tendency recall the gist of a memory rather than details.
In this study, researchers show that this switch from details to gist – from hippocampus to cortex – can be altered if people are given a drug that increases arousal by activating the brain’s noradrenaline system, provided the drug is given shortly after the memory is formed. As a result, people performed better than a placebo group in a memory task that required specific recall. It is worth noting that while detailed memories can be useful, the “gistification” process of memory consolidation is central to our ability to generalize and build mental models of the world.
Krenz et al. (2021) Noradrenergic arousal after encoding reverses the course of systems consolidation in humans. Nature Communications 12: 6054 DOI: https://doi.org/10.1038/s41467-021-26250-7
Precise theta for memory encoding
Rhythmic oscillations coordinate brain activity, with different frequencies of oscillation associated with different behaviors and cognitive states. The theta oscillation (~4-8 Hz) – the focus of this research – is important for memory, and is prominent in the hippocampus and entorhinal cortex when an animal explores its surrounds.
In this study, researchers artificially evoked oscillations and assessed the impact on a mouse’s memory. When the artificial oscillation occurred at frequencies below 10 Hz, memory was unaffected. But when the oscillation frequency was driven to or beyond 10 Hz, memory was impaired. The impairment occurred only if the artificial oscillation occurred during the memory encoding phase; memory retention and retrieval were unaffected.
Quirk et al. (2021) Precisely timed theta oscillations are selectively required during the encoding phase of memory. Nature Neuroscience DOI: https://doi.org/10.1038/s41593-021-00919-0