Execution of new trajectories toward a stable goal without a functional hippocampus.

The hippocampus is a critical component of a mammalian spatial navigation system, with the firing sequences of hippocampal place cells during sleep or immobility constituting a "replay" of an animal's past trajectories. A novel spatial navigation task recently revealed that such "replay" sequences of place fields can also prospectively map onto imminent new paths to a goal that occupies a stable location during each session. It was hypothesized that such "prospective replay" sequences may play a causal role in goal-directed navigation.

An analysis of the experiences of bereaved relatives and health care providers following palliative sedation: a study protocol for a qualitative international multicenter case study.

Background: Patients at the end-of-life may experience refractory symptoms of which pain, delirium, vomiting and dyspnea are the most frequent. Palliative sedation can be considered a last resort option to alleviate one or more refractory symptoms. There are only a limited number of (qualitative) studies exploring the experiences of relatives of sedated patients and their health care professionals (HCPs).

Shining a light on hippocampal remapping.

In this issue of Neuron, McKenzie et al. (2021) test the degree to which pre-existing biases in hippocampal circuits constrict the encoding of new information via artificial induction of place cell remapping. Their results suggest that the hippocampal spatial map encodes new information via pre-existing latent place fields.

Novelty and Dopaminergic Modulation of Memory Persistence: A Tale of Two Systems.

Adaptation to the ever-changing world is critical for survival, and our brains are particularly tuned to remember events that differ from previous experiences. Novel experiences induce dopamine release in the hippocampus, a process which promotes memory persistence. While axons from the ventral tegmental area (VTA) were generally thought to be the exclusive source of hippocampal dopamine, recent studies have demonstrated that noradrenergic neurons in the locus coeruleus (LC) corelease noradrenaline and dopamine in the hippocampus and that their dopamine release boosts memory retention as well.