Somatosensation In Social Perception

Meanwhile, in the same number of the same journal - Nature Reviews Neuroscience - one of the doyens of human mirror neurons - Christian Keysers - reports finding evidence for the firing of mirror neurons in the somatosensory cortices - those parts of the brain that receive and process incoming information from our sense organs - ears, eyes, touch sensors etc. etc. "Studies that measure brain activity while participants witness the sensations, actions and somatic pain of others consistently show vicarious activation in the somatosensory cortices", they say, in the abstract.

Mirrors, Mirrors Everywhere?

The debate over whether or not mirror neurons really exist, and whether or not they have been satisfyingly proved to exist in humans rumbles on. One bug-bear is the lack of direct observations of neurons firing in humans due to the inability of investigators to push probes into human brains except in very rare cases where brains are already being investigated for things like Parkinsons Disease. However, in this breezy piece in Nature Reviews Neuroscience, Leonie Walberg reports on some work where recordings of single-cell activity have been made, from several areas of human brain, that behave with mirror neuron properties.

The authors, she says, report activity in patients with implanted electrodes when they observed or executed grasping actions and facial expressions. Recordings were made from medial frontal cortex (which includes the anterior cingulate cortex, an important component of the 'social brain'), medial temporal cortex (which includes the amygdala - another important 'social brain'structure, and the hippocampus).

"Of the 68 'matching cells' detected, 33 showed increased firing during both the observation and execution of a particular action and 21 cells showed decreased firing in both conditions. Interestingly, in the remaining 14 neurons, the firing rate increased in one condition but decreased in the other."

The authors speculate that the decreased firing in some cells, which is not the classical mirror neuron condition, may have a role in suppressing execution of observed actions to ensure that we do not imitate every action we see. However this observation seems destined to further fuel the rather rancorous debate over mirror neurons being all things to all people. After all, mirror neurons were first reported in monkeys - a species that is very poor at imitation, whereas humans, if anything, over-imitate.

Two More "Brain-builder" Proteins

In my chapter BRAIN-BUILDERS I recount the tale of how the discovery of two genes responsible for microcephaly - ASPM and Microcephalin - has an evolutionary dimension in that both genes have accumulated substantial sequence evolution since the split from the common ancestor. Both genes affect the plane of the spindle in mitotic cell division of neuron progenitor cells such that cells can be kept in the totipotent state for longer - squeezing proliferation power out of the neuro-epithelium. Now a group of scientists at the Picower Institute at MIT have discovered two more proteins - Cdk5rap2 and pericentrin - that work together to regulate neural growth in the developing brain. Loss of function of these proteins, they report, causes microcephaly and osteodysplastic primordial dwarfism. Their normal action takes place in the developing neocortex and their mode of action was discovered using "knock out' mice.

Birds And Mammals Share A Common Brain Circuit For Learning

In my chapter CLEVER CORVIDS I point out that recent research comparing avian and mammalian brains has demonstrated that parts of both are derived from the same embryonic structures, which suggests that bird brains are not "bird-brains" after all. Here research on neurons in a part of the basal ganglia of the zebra finch - so-called area X which is involved in the learning of song - bear strong comparison to neural structures in the corresponding part of mammalian brains - the striatum and globus pallidus. As the scientists concerned are quoted saying: "Our results strongly suggest that the same brain circuits underlie learning in birds and mammals, despite the superficial differences in anatomy".

Creativity Linked To Mental Health

In the final chapter of NOT A CHIMP I talk about fresh research that has breathed life into much older ideas about the link between mania and creativity. Here a group of Scandinavian scientists carry the story still further with the discovery that highly creative people and schizophrenics have similar profiles of dopamine D2 receptors in the brain - particularly the thalamus (which acts as a filter for incoming material from the senses which is then passed on to neo-cortical structures for advanced processing). Schizophrenics and creatives have a lower density of D2 receptors in the thalamus, suggesting that this causes the thalamus to be less strict in its signal filtering. There is therefore a higher flow of signals from the thalamus which might, says the article, "be a possible mechanism behind the ability of healthy highly creative people to see numerous uncommon connections in a problem-solving situation and the bizarre associations found in the mentally ill".

As lead scientist Fredrik Ullen, explains: "Thinking outside the box might be facilitated by having a somewhat less intact box (the thalamus)".

Anthropocentrism - Born Or Made?

In the book, and in many of my recent posts, I have ground on about our innate human propensity for attributing human cognition to animals - anthropomorphism - and the way it bedevils comparative cognitive research. But where does such an ingrained cognitive bias come from? Are we born with it, or do we acquire it during child development? Most psychologists have assumed that anthropocentrism - favouring a human vantage point when it comes to comparing us to the animals and them to us - is a default position hardwired into babies and thence young children, but recent research, reported here, by a team of scientists from Northwestern University, challenges that view. They maintain that 3 year- olds do not have this anthropocentric bias, but, that by the time URBAN children are 5+, they do. The conclusion is that anthropocentrism is thrust upon developing children by the attitudes they are surrounded by as they grow up, and the biased way animal behaviour is represented in the media - tv programmes and kiddies books etc.