Molecular tricks are helping us understand how memories are stored
In 2015, Susumu Tonegawa and colleagues at MIT showed that changes in synaptic connections (i.e. synaptic plasticity) are not needed to store a memory, overturning years of dogma. The stored memory is instead housed in the pattern of neural activity, with synaptic plasticity providing the means to recall that activity pattern. Proof of this? Even when synaptic changes are prevented, a memory can still be accessed by artificially switching on the right cells.
In a new study, the same laboratory digs deeper into this phenomenon, providing a host of new evidence that memories can exist in a dormant state in the brain. Although unable to be recalled naturally, these memories can be accessed with some genetic and optical trickery. This body of research has implications for conditions of memory failure such as Alzheimer’s disease and retrograde amnesia.
Roy et al. (2017) Silent memory engrams as the basis for retrograde amnesia. Proceedings of the National Academy of Sciences 114(46): E9972-E9979 DOI: http://dx.doi.org/10.1073/pnas.1714248114
Teaching educational psychology to future teachers
Teacher education courses include instruction in educational psychology, but teachers often see these as too abstracted from the realities of the classroom to be very useful. What can be done to address this?
Daniel Willingham points out that whereas researchers need extensive knowledge of psychology theory, what matters for teachers is what can be applied in the classroom. As such, he recommends that experimental observations are prioritized for trainee teachers, with only enough theory to provide context and bind findings together. He also recommends simplifying descriptions of theories with analogies, even at the expense of perfect accuracy.
The author acknowledges that so far, there is little hard evidence that training in educational psychology actually helps classroom practice. But with a bigger focus on well-established experimental findings and their practical implementation, and less on theory, this could change.
Willingham (2017) A mental model of the learner: Teaching the basic science of educational psychology to future teachers. Mind, Brain, and Education 11(4) 166-175 DOI: http://dx.doi.org/10.1111/mbe.12155
Timing matters when laying down memories
Brain oscillations – rhythmic fluctuations in neural activity – act like conductors of the brain’s symphony. In the hippocampus, theta frequency oscillations (~4-8 Hz) have been implicated in coordinating memory formation. This raises the possibility that by promoting theta oscillations, we might help ourselves lay down memories.
Researchers at the University of Birmingham tested this by showing participants a series of videos that were each accompanied by one of several soundtracks. As participants watched and listened, the brightness and loudness were ramped up and down at theta frequency, producing theta frequency oscillations in visual cortex and auditory cortex. In some experiments, the loudness and brightness were varied at exactly the same time (i.e. “in-phase”), while in other experiments, the two were modulated slightly off kilter (i.e. “out-of-phase”).
When asked to recall which videos occurred with which soundtrack, participants did better when modulation occurred in-phase. This provides causal support for a role of synchronous theta oscillations in human memory formation.
Clouter et al. (2017) Theta phase synchronization is the glue that binds human associative memory. Current Biology 27(20): 3143-3148.e6 DOI: http://dx.doi.org/10.1016/j.cub/2017.09.001
tDCS can boost learning by synchronizing brain activity
tDCS (transcranial direct current stimulation) is a brain stimulation technique that has become popular with DIY brain hackers for its simplicity and accessibility. Electrodes placed on the scalp deliver a weak electrical current that is thought to modulate brain activity, but exactly how brain activity is altered is not clear, and nor is the effectiveness of tDCS widely accepted.
In this study, electrical recordings were made from within the macaque monkey brain while the animal learned to fix its gaze on a particular location of an image. During training on this task, tDCS was sometimes applied to the monkey’s prefrontal cortex (PFC). This non-invasive stimulation helped the animals learn the task more quickly, while also changing how well high-frequency (gamma) brain waves in the PFC synced with those in the inferotemporal cortex. The results suggest that tDCS can aid learning by synchronizing gamma brain waves across brain regions.
Krause et al. (2017) Transcranial direct current stimulation facilitates associative learning and alters functional connectivity in the primate brain. Current Biology 27(20):3086-3096.e3 DOI: http://dx.doi.org/10.1016/j.cub.2017.09.020