Flexible spatial navigation, e.g. the ability to take novel shortcuts, is contingent upon accurate mental representations of environments-cognitive maps. These cognitive maps critically depend on hippocampal place cells. In rodents, place cells replay recently travelled routes, especially during periods of behavioural inactivity (sleep/wakeful rest). This neural replay is hypothesised to promot...

Emotionally arousing events like encounter with an unfamiliar con-species produce strong and vivid memories, whereby the hippocampus and amygdala play a crucial role. It is less understood, however, which neurotransmitter systems regulate the strength of social memories, which have a strong emotional component. It was shown previously that dynorphin signalling is involved in the formation and e...

Many studies in diverse organisms, including humans, have demonstrated a fundamental role for sleep in the formation of memories. A new study by Berry et al. indicates that, in fruit flies, sleep accomplishes this in part by preventing an active process of forgetting.

Transient global amnesia is an alarming but benign disorder of middle age, which prevents both the formation of new memories, and the retrieval of recently formed ones, for some hours. Research over the last 10 years has shed light on the epidemiology, neuropsychology, functional anatomy and differential diagnosis of this distinctive condition, and clarified its management.

Considerable evidence suggests that the formation of long-term memories requires a critical period of new protein synthesis. Recently, the notion that some of these newly synthesized proteins originate through local translation in neuronal dendrites has gained some traction. Here, we review the experimental support for this idea and highlight some of the key questions outstanding in this area.

Before a natural sound can be recognized, an auditory signature of its source must be learned through experience. Here we used random waveforms to probe the formation of new memories for arbitrary complex sounds. A behavioral measure was designed, based on the detection of repetitions embedded in noises up to 4 s long. Unbeknownst to listeners, some noise samples reoccurred randomly throughout ...

The ERK1/2 MAP kinase (MAPK) signaling pathway is important for the formation of long-term memories. In this issue, Shimizu et al. (2007) provide new insight into the regulation of this pathway by demonstrating that activation of MAP kinase occurs through the calcium-dependent degradation of SCOP (suprachiasmatic nucleus circadian oscillatory protein) by the protease calpain.