Mice show empathy

Science 312, 1967–1970 (2006)
A mouse watching a cage-mate writhe in pain will writhe more itself, an observation that Jeffrey Mogil and his team at McGill University in Montreal conclude is evidence of rodent empathy.
The researchers tested mice in twos, giving one or both mildly painful shots of acetic acid. If the two were strangers, they behaved as if they were on their own. But if they had lived together for a few weeks, and both got a shot, they both showed more abdominal constrictions, termed writhing, than when given a shot alone. The effect vanished if the roomies could not see one another.
Empathy has previously been considered an attribute of primates alone. Of course, the empathetic response does not indicate that the mice consciously felt sorry for one another — only that they respond to each other's pain.

It's All in the Mind

How do physiological and molecular variation combine to create a range of motivational drives that becomes manifest as a range of behaviors? Champagne et al. report measurements of dopamine in the nucleus accumbens of female rats caring for (licking and grooming) their pups. This region of the brain is known to contribute to motivating behaviors, particularly those that are followed by reward, such as the consumption of food. The increase in dopamine preceded the initiation of licking and grooming acts by the mothers, and the size and duration of the dopamine signal correlated with the duration of the act. Furthermore, mothers previously scored as high or low in licking/grooming (greater than 1 standard deviation from the mean of a normally distributed group) exhibited consistently high or low scores in the dopamine signal and in the density of dopamine receptors in the shell of the nucleus accumbens. Taken together with earlier studies in this series, these results begin to establish a neurochemical basis for individual differences in maternal behavior.
J. Neurosci. 24, 4113 (2004).

Neurons in the orbitofrontal cortex encode economic value

Economic choice is the behaviour observed when individuals select one among many available options. There is no intrinsically 'correct' answer: economic choice depends on subjective preferences. This behaviour is traditionally the object of economic analysis1 and is also of primary interest in psychology2. However, the underlying mental processes and neuronal mechanisms are not well understood. Theories of human and animal choice1 have a cornerstone in the concept of 'value'. Consider, for example, a monkey offered one raisin versus one piece of apple: behavioural evidence suggests that the animal chooses by assigning values to the two options4. But where and how values are represented in the brain is unclear. Here we show that, during economic choice, neurons in the orbitofrontal cortex (OFC) encode the value of offered and chosen goods. Notably, OFC neurons encode value independently of visuospatial factors and motor responses. If a monkey chooses between A and B, neurons in the OFC encode the value of the two goods independently of whether A is presented on the right and B on the left, or vice versa. This trait distinguishes the OFC from other brain areas in which value modulates activity related to sensory or motor processes. Our results have broad implications for possible psychological models, suggesting that economic choice is essentially choice between goods rather than choice between actions. In this framework, neurons in the OFC seem to be a good candidate network for value assignment underlying economic choice.