Volume 24 Issue 5, May 2021

Disrupting reconsolidation of the maladaptive memories underlying post-traumatic stress disorder (PTSD) could be transformative for treatment. However, patients cannot undergo the direct re-exposure to trauma-cues used to induce reconsolidation in animal studies. Ressler and colleagues report ‘covert’ memory reactivation in rats, bolstering hopes for translation of reconsolidation-based interventions.

In new research, Smith et al. identify thousands of novel genetic associations with human brain structure and function, including those on the X chromosome, by analyzing ~4,000 MRI-derived traits measured in almost 40,000 individuals from the UK Biobank resource.

RNA localization is a defining and intricately regulated feature of neuronal physiology. Fernandopulle et al. review how altered RNA transport and local translation might inform understanding of neuronal disease.

Vast networks of capillaries feed the brain. Hartmann et al. show that pericyte contractility is critical for maintenance of enduring capillary tone, which sets an optimized rate and distribution of blood flow through brain capillary networks.

Yin et al. show that motor learning is delayed in mice with 16p11.2 deletion, associated with abnormal ensemble activity and delayed spine remodeling in motor cortex and reduced activity of of locus coeruleus noradrenergic neurons. The motor-related abnormalities were rescued by activation of ocus coeruleus noradrenergic neurons.

Astrocytes regulate synaptic transmission. Carlsen et al. report that spinal astrocytes activated by endocannabinoids inhibit excitatory synaptic transmission and, thereby, decrease tremor.

Early life stress (ELS) promotes susceptibility to the effects of chronic stress in adulthood. Kronman et al. show that ELS alters H3K79me2 in D2 medium spiny neurons in the nucleus accumbens and that this underlies the susceptibility to the effects of subsequent stress.

This study shows that hippocampus-dependent fear memories can be indirectly reactivated, captured and pharmacologically attenuated in rats. This reinforces the utility of imaginal reminders to target traumatic memories in humans.

Although successful memory recall usually involves activation of broadly distributed networks, Vetere, Xia et al. show that the active disengagement of the anterodorsal thalamic nucleus is necessary for recall specifically at remote time-points.

El-Gaby et al. combine multiunit recordings and optogenetic silencing in the mouse hippocampus and uncover a primary role for millisecond-timescale neural coactivity in encoding behavioral contingency information and supporting memory retrieval.

Combining virtual reality and large-scale calcium imaging, the authors demonstrate that hippocampal place cell remapping across contexts can be precisely predicted by the experience of the animal and approximates optimal probabilistic inference.

During implicit learning, the authors find that sensory representations in mouse auditory cortex evolve over time, rotating into orthogonal memory representations. This allows short-term memories to avoid interference from new sensory inputs.

Hennig et al. study how changes in internal state interact with learning in primates. They report stereotyped activity fluctuations in the motor cortex that reflect the animal’s level of engagement and predict how quickly the animals learned.

The Elliott and Smith teams used imaging and genetics data from 40,000 volunteers in the UK Biobank healthcare study, discovering new genetic influences over brain structure and function, which are of relevance to both rare and common diseases.

The authors develop a genetically encoded GPCR-based sensor to image serotonin dynamics in behaving animals with high specificity, sensitivity and spatiotemporal resolution.