7/7 None of this demonstrates that C. elegans is conscious. But perhaps some of the neural dynamical properties that contribute to making consciousness possible in more complex species have very ancient evolutionary roots.

6/7 What is particularly surprising is that anesthetics acting through different molecular mechanisms produce such similar changes in neural activity. This suggests that different pharmacological pathways can lead to a common functional state of the nervous system.

5/7 Interestingly, in two macaques anesthetized with propofol, electrical stimulation of the centromedian thalamus reversed some of these changes and restored behavioral responsiveness. And this happened while the animals were still receiving the anesthetic (!)

4/7 Synchronization between brain regions also decreases. Their activity becomes less coordinated, probably compromising the integration of information. The authors describe this combined effect as the "spatiotemporal isolation" of neural activity.

3/7 One of these changes involves a loss of temporal continuity in neural activity: under anesthesia, activity in a given region becomes less dependent on its own previous activity. In other words, information appears to persist for less time in ongoing neural activity.

2/7 The researchers studied six species: humans, macaques, marmosets, mice, zebrafish, and C. elegans. Despite their differences and the use of anesthetics with distinct mechanisms of action, they identified 485 features of neural activity that changed consistently.

6/7 Both the dangerous hyperthermia and the recovery of functions through new neural circuits strongly recall the case I recently discussed in another thread: an elderly woman who recovered several functions after a deep sleep-like state, also with suspected hyperthermia.

5/7 The authors suggest that the recovery of normal behavior despite the lack of electrophysiological evidence may be due to increased structural plasticity: new connections that restore functions without restoring the damaged circuits themselves.

4/7 It is also interesting that, although the rats recovered from their memory impairments, the authors did not find a clear electrophysiological signature distinguishing them from rats that had not received psilocybin.

3/7 Also, at the tolerated dose, the rats performed almost like control animals in some memory tasks. But at intermediate and high doses, the animals did not survive (hyperthermia). Brains altered in this way may tolerate the serotonergic challenge posed by psilocybin poorly.

2/7 There are some important caveats before anyone thinks this is a solution to the disease. These were ICV-STZ rats and, although this model is used to study Alzheimer’s-like pathology, it does not fully reproduce human Alzheimer’s disease. (This is a horribly invasive study)

We are fish This is a good reminder that "fish" is an artificial term with practical use, but no actual cladistic validity. After all, humans should be classified as fish, too.