Many have written of the experience of mathematical beauty as being comparable to that derived from the greatest art. This makes it interesting to learn whether the experience of beauty derived from such a highly intellectual and abstract source as mathematics correlates with activity in the same part of the emotional brain as that derived from more sensory, perceptually based, sources. To determine this, we used functional magnetic resonance imaging (fMRI) to image the activity in the brains of 15 mathematicians when they viewed mathematical formulae which they had individually rated as beautiful, indifferent or ugly. Results showed that the experience of mathematical beauty correlates parametrically with activity in the same part of the emotional brain, namely field A1 of the medial orbito-frontal cortex (mOFC), as the experience of beauty derived from other sources.

In this work, we address an important but unexplored topic, namely the neural correlates of hate. In a block-design fMRI study, we scanned 17 normal human subjects while they viewed the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject and this was used as a covariate in a between-subject random effects analysis. Viewing a hated face resulted in increased activity in the medial frontal gyrus, right putamen, bilaterally in premotor cortex, in the frontal pole and bilaterally in the medial insula. We also found three areas where activation correlated linearly with the declared level of hatred, the right insula, right premotor cortex and the right fronto-medial gyrus. One area of deactivation was found in the right superior frontal gyrus. The study thus shows that there is a unique pattern of activity in the brain in the context of hate. Though distinct from the pattern of activity that correlates with romantic love, this pattern nevertheless shares two areas with the latter, namely the putamen and the insula.

We pursued our functional magnetic resonance imaging (fMRI) studies of the neural correlates of romantic love in 24 subjects, half of whom were female (6 heterosexual and 6 homosexual) and half male (6 heterosexual and 6 homosexual). We compared the pattern of activity produced in their brains when they viewed the faces of their loved partners with that produced when they viewed the faces of friends of the same sex to whom they were romantically indifferent. The pattern of activation and de-activation was very similar in the brains of males and females, and heterosexuals and homosexuals. We could therefore detect no difference in activation patterns between these groups.

Near infrared spectroscopy (NIRS) is used to measure global changes in cerebral haemodynamics. We have adapted the technique to measure regional changes in response to a visual stimulus. Ten volunteers were exposed to a computer generated visual stimulus designed to activate a large area of the visual cortex, including V1, V2, V3, V4 and V5. The stimulus was on for 30 s and off for 30 s. Changes in the concentrations of oxyhaemoglobin ([HbO2]) and deoxyhaemoglobin ([Hb]) were measured using a commercial spectrometer (NIRO500), over the occipital cortex. The data were summed over ten cycles. As a control, the experiment was repeated over the frontal cortex. For each subject [HbO2] increased during stimulation, and decreased when the stimulus was off. The mean (+/- s.e.m.) change in [HbO2] was 0.54 +/0 0.14 micromol 1(-1). The change in total haemoglobin concentration, given by [HbO2] + [Hb] was 0.61 +/- 0.21 micromol 1(-1), equivalent to a rise in cerebral blood volume of 0.04 +/- 0.01 ml 100 g(-1) which is about 2% of the total cerebral blood volume. There was no significant change in [HbO2] over the frontal cortex, implying that the changes in blood volume originated in the occipital lobe. This demonstrates that NIRS provides a non-invasive method of measuring regional changes in cerebral haemodynamics as a result of visual stimulation.