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Guy Kahane’s Posts

The Stuff Dreams Are Made Of

Studies of the content of dreams confirm what most of us already suspect: dreams are more likely to be nasty than pleasant, or as the researchers put it, “negative dream contents are more frequent than corresponding positive dream contents”. A recent study reports that threatening experiences are more frequent and intense in dreams than in real life. All this is in line with the entertaining (and not implausible) ‘threat simulation theory’ of dreams, according to which the evolutionary function of dreams is to simulate threats so that our ancestors could spend their nights rehearsing attacks by enemies and predators.

So dreams have a serious negative bias. All of this might have been extremely useful back then. But an unwelcome consequence is that we spend a large portion of our life in pointless misery. Clinical depression is often understood as a disposition to obsessively accentuate the negative. It seems all of us are clinically depressed during certain hours of the night. Think of a human life and how many hours of sleep it contains. Of these, many are spent dreaming. And most of these dreams are unpleasant in different ways. If we add all this up, dreaming makes our lives significantly worse, on balance. Shouldn’t we do something about this?

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Peering into the mind and ‘new threats to privacy’

In recent studies, neuroscientists have been able to use brain imaging to reliably predict inner states such as lying or intention. In a groundbreaking study published in a recent issue of Nature (and briefly summarised here, here and here), Kay and his colleagues used functional magnetic resonance imaging (fMRI) to make predictions about what subjects were seeing. Using a complex mathematical model based on decades of research into the human visual cortex, measured brain activity to estimate which grayscale natural image the subject was seeing at a given point in time. This goes beyond prior attempts at ‘brain reading’ in that the analysis did not merely use simple artificial stimuli or generic statistical signal-processing methods to identify neural patterns but employed data about the early stages of visual processing to develop a model that was then able to accurately predict which of a large number of novel and complex natural images was seen by the subject.

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Restoring Sensation to Amputees’ Lost Limbs

Scientists at the Rehabilitation Institute of Chicago and Northwestern University made two amputees ‘feel’ their lost arms by rerouting to their chest the key nerves that transfer sensations from hand to brain. After several months, stimulation to the area of the nerves would produce rich sensations experienced as if occurring in the missing limbs. Interestingly, the patients could still distinguish between sensory stimulation of chest nerves and that of the rerouted arm nerves.

For a summary, see Yahoo News

For the original paper, see PNAS paper

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Imaging the Political Brain

In an interesting study published in the Journal of Cognitive Neuroscience in 2006 but widely circulated earlier, Drew Westen and his colleagues at Emory University used fMRI to image the brains of committed Democrats and Republicans before the 2004 Presidential election. Although the subject matter was topical, the aim of the study was not to… Read More »Imaging the Political Brain