Category Archives: sleep

To see others as we see ourselves

In psychology there is a theory about the ‘fundamental attribution error’, the error in how we attribute causes to actions. When we look at our own actions, they are caused by our cognition in the circumstances in which we are deciding what to do. When we look at the actions of others, they are caused by their personality or character traits. So we do not really take into consideration the circumstances of others when we judge their actions. Nor do we consider the fixed patterns of our own behavior that do not enter into our conscious thoughts when we judge our own actions. We just do what is reasonable at the time and they just do what they always do. I can be too busy to help while they can be too thoughtless. This is a problem for us but at least we can understand the problem and occasionally overcome it. (My way to deal with it is to just assume that people are intelligent and well-meaning most of the time. If they do something that seems dumb or nasty, I look at the circumstances to see if there is a reasonable explanation. There very often is. I realize that this view of my own behaviour is somewhat ironic in its internal attribution – well nothing is perfect.)

But this problem with attribution is much greater than human social interaction. We do the same thing with animals. Elephants were tested for self recognition with the mirror test. If they recognize a black spot appearing on their forehead then it is clear that they know it is their forehead. Elephants failed the test and so they were said to not have a sense of self. It turned out that the mirrors used were too small. The elephants could not make out that it was an elephant in the mirror let alone themselves. If we start out underestimating an animals intelligence, and either not test that assumption or test it in a way that is inappropriate for the animal – then we are making a big attribution error.

There is an assumption on the part of many that vertebrate brains are quite different in the various sorts of vertebrates. This is not true! All animals with a spine have the same brain pattern with the same regions. All vertebrates have seven parts and no more or less: accessory olfactory bulb; cerebellum; cerebral hemispheres; medulla oblongata; olfactory bulb; optic tectum; and pituitary gland. There are differences in size, details and subdivisions, but there are no missing parts. (R.G. Northcutt; Understanding Vertebrate Brain Evolution; Integr. Comp. Biol. 2002 42(4) 743-756). There is every reason to believe that the brain works in fundamentally the same way in mammals, birds, reptiles, amphibians and fish. And by and large, this same pattern of brain has the same functions – to move, find/eat food, escape enemies and so on. It is obvious that animals have motor control and sensory perception.

What evidence is there that other animals have emotions, memory, or consciousness? Can they be automatons with no mental life? The reports trickle in year after year that add to the evidence that animals have a mental life similar to ours.

Reptiles probably dream. Most animal species sleep, from invertebrates to primates. However, neuroscientists have until now only actively recorded the sleeping brains of birds and mammals. Shein-Idelson et al. now describe the electrophysiological hallmarks of sleep in reptiles. Recordings from the brains of Australian dragons revealed the typical features of slow-wave sleep and rapid eye movement (REM) sleep. These findings indicate that the brainstem circuits responsible for slow-wave and REM sleep are not only very ancient but were already involved in sleep dynamics in reptiles.(Shein-Idelson, Ondracek, Liaw, Reiter, Laurent; Slow waves, sharp waves, ripples, and REM in sleeping dragons; Science 2016 Vol 352 (6285) 590-596) These wave types in sleep also are evidence for a memory system similar to ours.

Fish don’t make noise or wave their fins to show emotion but that does not mean they don’t have emotions. “Whether fishes are sentient beings remains an unresolved and controversial question. Among characteristics thought to reflect a low level of sentience in fishes is an inability to show stress-induced hyperthermia (SIH), a transient rise in body temperature shown in response to a variety of stressors. This is a real fever response, so is often referred to as ‘emotional fever’. It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles), in association with the evolution of consciousness in these groups. According to this view, lack of emotional fever in fishes reflects a lack of consciousness. We report here on a study in which six zebrafish groups with access to a temperature gradient were either left as undisturbed controls or subjected to a short period of confinement. The results were striking: compared to controls, stressed zebrafish spent significantly more time at higher temperatures, achieving an estimated rise in body temperature of about 2–48C. Thus, zebrafish clearly have the capacity to show emotional fever. While the link between emotion and consciousness is still debated, this finding removes a key argument for lack of consciousness in fishes.” (Rey, Huntingford, Boltana, Vargas, Knowles, Mackenzie; Fish can show emotional fever: stress-induced hyperthermia in zebrafish; 2015 Proc. R. Soc. B 282: 20152266)

One of the problems with comparing the brains of different vertebrates is that they have been named differently. When development is followed through the embryos, many differently named regions should really have a single name. Parts of the tectum are the same as our superior colliculus and they have been found to act in the same way. They integrate sensory stimuli from various senses. They can register whether events are simultaneous. For example in tadpoles the tectum can tell if a sight and vibration stimulus are simultaneous. That is the same function with the same development in the same part of the brain in an amphibian and a mammal. (Felch, Khakhalin, Aizenmen; Multisensory integration in the developing tectum is constrained by the balance of excitation and inhibition. 2016 eLife 5)

We should be assuming that other vertebrates think like we do to a large extent – just as we should assume that other people do – and try to understand their actions without an attribution error.

REM sleep and saccades

When we sleep we pass through a cycle of types of sleep. One of these types is REM (rapid eye movement) sleep and if we are awqkened during REM sleep we report dreaming. During REM sleep movement of the body is suppressed (except of sleep-walkers). Only the eyes are moving under the eye lids. These eye movements resemble the regular rapid movement of the eyes from one fixation to another when awake, called saccades.

A recent paper (Thomas Andrillon, Yuval Nir, Chiara Cirelli, Giulio Tononi, Itzhak Fried. Single-neuron activity and eye movements during human REM sleep and awake vision. Nature Communications, 2015; 6: 7884 DOI: 10.1038/ncomms8884) compares REMs and saccades. The research was carried out on epileptic patients being prepared for surgery by having electrodes implanted deep in the brain for 10 days. In this case there were 9 patients with electrodes in the medial temporal lobe. The MTL is thought of as a bridge between vision and imagining visual scenes on the one hand and memory on the other. As well as recording activity from neurons, the researchers also recorded movement of the eye muscles and conventional EEC from various parts of the scalp.

They found the REMs and saccades were very similar in their pattern of activity in the brain. This says something very interesting about consciousness. When the eyes move in a saccade there is saccadic suppression of the information arriving via the optic nerve from the eyes. There are signals arriving and they affect brain activity but they do not register in consciousness; the gap in visual information is also hidden from consciousness. We are, in affect, as when watching a movie, viewing a series of still images and creating a continuous effect. So saccades are associated with creating a continuous effect from a train of discrete, discontinuous signals. (At least that is one theory.)

The type of dreaming that is associated with REM sleep can be seen as a very similar process, a form of consciousness that is cut off from actual sensory input and from control of skeletal muscles. The purpose of these dreams is unclear but it probably involves some aspect of memory processing. So perhaps the dreams are a series of discontinuous images divided by REMs, leaving no trace of the gaps during the eye movement, as in awake consciousness.

But why would the eye movement by required to create the conscious process during sleep? Perhaps it drives it, or controls it, or times its components, or perhaps it is not required but cannot be eliminated. What interesting questions! They may help to understand conventional consciousness as well as dreams.

Here is the abstract: “Are rapid eye movements (REMs) in sleep associated with visual-like activity, as during wakefulness? Here we examine single-unit activities (n 1⁄4 2,057) and intracranial electroencephalography across the human medial temporal lobe (MTL) and neocortex during sleep and wakefulness, and during visual stimulation with fixation. During sleep and wakefulness, REM onsets are associated with distinct intracranial potentials, reminiscent of ponto-geniculate-occipital waves. Individual neurons, especially in the MTL, exhibit reduced firing rates before REMs as well as transient increases in firing rate immediately after, similar to activity patterns observed upon image presentation during fixation without eye movements. Moreover, the selectivity of individual units is correlated with their response latency, such that units activated after a small number of images or REMs exhibit delayed increases in firing rates. Finally, the phase of theta oscillations is similarly reset following REMs in sleep and wakefulness, and after controlled visual stimulation. Our results suggest that REMs during sleep rearrange discrete epochs of visual-like processing as during wakefulness.