Encephalon #24 – Hamsters, H.M., and more

Somatosensory cortex in a mouse brain. Picture by cudmore.

Welcome to the 24th issue of Neuroscience blogging carnival Encephalon! This issue covers all levels of analysis, from neurobiology to morality and altruism, via a quote that produces positively disturbing mental images…

H.M. is probably the most famous case in neuropsychology. Following surgery that removed his hippocampus bilaterally, he has had no apparent ability to form explicit memories for over 50 years. The Neurophilosopher has written a nice review of what is known about this H.M.’s condition, and what it tells us about memory.

In synaesthesia, the senses appear to be cross-wired – for instance, some people with this condition experience that musical notes have colour, in addition to their musical qualities. Madam Fathom has a summary of current theory and research in this area, while the Neurocritic reports on some specific findings that synaesthesia is associated with greater connectivity in the inferior temporal cortex.

The Neurocritic also reports on a rare opportunity to make electrode recordings of neuronal activity in the human nucleus accumbens to investigate its role in reward learning. The nucleus accumbens is a subcortical structure that is thought to function as the brain’s “pleasure centre.” Based on this, the electrodes were originally implanted in these humans as an attempt to alleviate severe depression through direct electrical stimulation of this pleasure centre, as the Neurocritic outlines in a second post on the same topic.

Motor cortex layer V, FluoroNissl stained. Picture by Neurollero.

A Blog Around the Clock reports on a recent finding that small doses of Viagra helped hamsters adjust faster to a 6-hour shift in their day-night cycle, as compared to controls that received saline. The obvious conclusion is that Viagra might help in preventing jet lag, but this conclusion may not be justified given the data, as this post outlines. ABAC also contributes a criticism of the simplistic notion that there are genes for sleep.

It has been known for a while that animals kept on calorie-restricted diets can live considerably beyond their normal live-span. Ouroboros reports on the shocking finding that rats that are kept this way seem to be a little unhappy. Beyond this, however, there is a good discussion on the methodological issues in this research, and the possible implications for human dieters.

Some have argued that recent evidence of the biological basis of morality has far-reaching implications for our current understanding of personal responsibility, particularly in the context of the criminal justice system. BioBlog takes this notion to task in an incisive post.

Like personal responsibility, the issue of sex differences in cognitive abilities is usually a hot-button topic, but Neurozone tackles it in a strictly empirical fashion, reporting on recent findings on differences in mental rotation, verbal fluency, and object location memory.

Cortical layer V pyramidal cells, various stains. Picture by Neuronello.

Pure Pedantry wins the quote of the issue award with the following:

The manner of spontaneous activity in neuron cultures can be described as what I suspect sex with an old person is like — passionate but over with relatively quickly.

After that, how can you resist learning more about how information can be stored in cultured neurons? It may just help put that picture out of your head.

Finally: the Neuroscience part of the blogosphere is quite large, spread over a bunch of different websites. For those interested in the cognitive side of things, PsyBlog’s three-part series on the best Psychology blogs is an excellent starting point (Part 1, Part 2, Part 3).

Thanks to everyone who contributed! The next issue of Encephalon will be hosted by Jeremy of the previously mentioned PsyBlog, on June 18.