14/07/2010 by admin.

Is seems generally accepted in neuroscientific circles that the brain predicts the results of motor action, constructs a prediction of sensory signals, compares the prediction with the outcome and uses the error to correct motor action and perceptual processes. It is also accepted that the prediction is singular and global in nature. Many assume it is Bayesian, at least in spirit. Below is some representative evidence for this predictive process being linked to the awareness that we experience. What we are aware of is the prediction.

(This was written to appear elsewhere and so I have avoided the use of the word consciousness in order to bypass fruitless discussion. But most neuroscientists do not avoid the word and in fact, many consider it the object of their investigations. If you find the wording awkward, then just substitute consciousness for awareness.)

1. The failure of simultaneity between moving events and stationary objects: Nijhawan’s experiment had an object move across the visual field and pass a flashbulb on the way. The flashbulb flashed at exactly the moment that the object passed it. Subjects reported perceiving the object pass the bulb before the bulb flashed. The brain ’sees’ a split second into the future for moving objects but not individual stationary ones. Bai’s showed that there were more mistaken ‘out’ calls in tennis than ‘in’ calls because the officials perceive the ball is having moved further then it had.

2. The systematic nature of some types of visual illusion: Changizi’s investigation of illusions mathematically predicts the extent that certain attributes of an object (smaller size, slower speeds, greater luminance contrast, farther distance, low eccentricity, greater proximity to the vanishing point, greater proximity to the focus of expansion) produce similar perceptual effects (increased perceived size, increased perceived speed, decreased perceived luminance contrast, deceased perceived distance). This shows that the visual system uses mechanisms for compensating for neural delay during forward motion in order to ‘perceive the present’.

3. Problems with timing of normal sensory input and direct stimulation of the cortex: Libet’s experiment showed that stimulation of the skin reached awareness in a much shorter time then stimulation of the exposed surface of the cortex. This prompted him to propose a system of backward referrals of the timing of events. A much cleaner explanation is a predictive projection into the future occurs in normal awareness.

4. Comprehension of language has a predictive nature: Berkum reported that event-related-potentials show the same pattern for unexpected words as for actual grammatical errors. This implies a ‘look ahead’ feature in language comprehension that produces surprise when predictions are wrong.

5. There is an error registering system in the brain: Firth states that the brain is Bayesian, correcting its understanding on the basis of comparing prediction with current input. He states that the dopamine signal is a prediction error indicator. Dopamine neurons become more active if a good surprise happens, do not change their activity if there is no surprise and become less active if a negative surprise happens. Menon’s investigation of Go/NoGo experiments shows clear error-related activity (named ERN and ERP) in a wide network of cortical areas. Others have slightly different statements of the error registering system but all seem to agree that errors are identified and corrected. A prediction is needed in order to generate an error signal.

6. Prediction is required for movement: Morsella has a theory that explains much about awareness. It postulates that it is used to meld together separate skeletomotor plans to avoid conflict. The conflict would only be apparent if our awareness predicted the course of the somewhat independent plans to see how they interacted with each other and the environment before the conflict actually happened. Llinas and Roy postulate that the main function of brain is a global one to implement intelligent motricity through prediction of the consequences of impending motion. They have outlined a thalamocortical system to do this that resembles the ‘neural correlates of consciousness’.

7. Energy use by the sensory areas of the brain is higher for unexpected input: Alink’s investigation found that the response in V1 to unexpected signals was higher than for expected ones. This is thought to be the result of feedback from higher levels of predictive information.

8. Reaching awareness takes time: Results of the bulk of experiments following the neural events leading up to awareness, it takes about 300msec from event to awareness of the event. There appears to be no evidence that we appear to live our lives a third of a second out of sync with the world. Predictive awareness eliminates this problem.

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24/05/2010 by admin.

This blog has reached its second birthday and it is time for a little summary. I have made a list of general ideas/questions that I am trying to investigate, and then, for each heading, I list the posts that apply to that idea.

Purpose of the blog

The aim of this blog is to prepare people for the revolution that is going to happen now in neuroscience. The very first post (1 Jun 08 aims ) outlined the scope of the blog. The aims are enlarged on later in (10 Aug 08 scientific shocks). To give an indication of the type of material that was intended in the blog an early post gave a list (12 Jun 08 what do we know about consciousness) and another gave probable functions (2 Jul 08 does consciousness have a function). Putting consciousness in context was the purpose of (9 Oct 08 one way to look at consciousness).

A different way to look at consciousness

Some posts have been specifically written to help people come to grips with a different way of viewing their mental life. These posts hardly contain any quotes or links to scientific material. I have used some descriptions of my own way of seeing myself: (6 Jun 08 living without a conscious mind) (10 Jul 08 decisions) (15 Aug 08 who is watching) (18 Oct 08 why make problems) (15 Nov 08 metaphors for consciousness) (30 Nov 08 metaphor) (15 Dec 08 a few definitions) (18 Mar 09 Little thought experiment) (22 Feb 09 A framework) (23 Apr 09 History of the quest) (29 Sep 2009 mind maintenance) (11 Feb 10 definitions of consciousness) (21 Apr 10 mind maintenance 2)

Some posts look at more specific problems in understanding consciousness

• The question of how qualia (the qualities of our experience) are produced has been a problem, especially for philosophers. (13 Jun 08 why not) (21 Sep 08 the wrong questions) (5 Jan 09 Experiencing someone else’s qualia) It is not yet clear how the binding of qualia to objects or concepts is done. (26 May 09 the location of objects) (22 Jun 09 inexpressible experience) (05 Oct 09 colour binding) (15 Jan 10 a comment) (8 Feb 10 the purpose of colour) (22 Mar 10 perception does not depend on sensation)

• Consciousness includes awareness of fringe events. (25 Oct 08 a certain feeling) (12 Nov 08 fringe consciousness) (3 Dec 08 confidence) (24 Jan 09 Feeling a presence) Embodiment may be key to fringe qualia. (11 May 09 movement as the foundation) (23 May 09 two way arrow) (29 May 09 embodiment) (23 Sep 09 a pain metaphor) ( 7 Nov 09 the body loop) (10 Dec 09 metaphor 2) (12 Apr 10 feeling a presence) (6 May 10 control of emotion) (9 May 10 emotional feeling) (12 May 10 method acting) (15 May 10 embodied power)

• There is also a problem of what to do about free will. The mechanics of intention, producing a movement command, and moving is complex, not at all is it feels consciously (26 Jul 08 the interpreter) (17 Sep 08 the problem of free will) (15 Oct 08 a feeling of will) (31 Oct 08 virtual agency) (3 Nov 08 Llinas) (6 Nov 08 more Llinas) (18 Nov 08 decisions without frontal lobe activity) (14 Jan 09 The moment of decision 1) (17 Jan 09 The moment of decision 2) (14 May 09 an odd result)(20 May 09 not so odd result) (17 Oct 09 some clarity on rewards) (30 Jan 10 prediction as intent) (5 Feb 10 an old argument) (9 Apr 10 today’s vitalism) (15 Apr 10 are there mirror neurons in humans) (24 Apr 10 No-go control)

• A spatial construction is basic to consciousness, used for location and other maps. (19 Aug 08 the 3D world) (30 Sep 08 built-in sat-nav) (2 Jan 09 Border cells) (25 Jul 09 time and space) (21 Aug 09 3D revisited) (24 Aug 09 which way is north?) (26 Oct 09 the maps in our minds)

• There is one is probably one mechanism for various types of awareness. And there are various states akin to consciousness (4 Sep 08 shared workspace) (8 Sep 08 what goes on in dreams) (3 Oct 08 consciousness in Zen meditation) (21 Nov 08 default network) (9 Dec 08 hypnosis) (2 May 09 baby mind)(17 May 09 the realness of virtual reality) (28 Jul 09 locked in consciousness) (20 Oct 09 near death EEG spikes) (7 Dec 09 reborn) (14 Feb 10 default network gone in coma) (16 Mar 10 what happens in meditation) (31 Mar 10 altered states – alcohol) 18 Apr 10 the usefulness of dreams) Thinking can be different when it does not have to be tied to awareness of the thinking. (27 Sep 08 eureka). Possibly imagination can be different from experience (1 Feb 09 Visual imagery).

• An important question is how we live in the present when it takes time for the brain to process information and render it part of consciousness. (24 Jun 08 living in the present) Changizi explains some visual illusions by projection into future (26 Aug 08 living in the present 2) It affects tennis refs (9 Nov 08 prediction). Not only does it take time to produce conscious experience, the process is like frames of a movie, so it is discontinuous rather than being continuous. (19 Jul 08 watching the movie) (27 Aug 09 clock speeds). Also (26 Jan 09 Surprise) (6 Mar 09 Up the garden path) (29 Oct 09 sense of time) (13 Mar 10 blinking together). Summarized in (6 Aug 09 Property of consciousness 1)

• What is the relationship between consciousness and our sense of self? Does a theory-of-mind apply to us as well as others. (22 Oct 08 the homunculus problem) (8 Jan 09 Self is not simple) (9 Mar 09 Meta-representation) (08 Apr 09 Conscious computer) (28 Jun 09 unwilling to see yourself) (13 Jul 09 the guessing trick) (22 Jul 09 Eco cells) (18 Aug 09 Out of body experience) (8 Sep 09 two selves) (26 Sep 09 what are mirror neurons doing) (10 Nov 09 out of body 2) (13 Nov 09 Avatars) (28 Dec 09 I and me) (3 Mar 10 no voters) (6 Apr 10 going native) (21 May 10 mirror neurons in autism)

• Personally I suspect a close relationship between consciousness and memory. (4 Feb 09 Towards understanding working memory) (7 Feb 09 Memory) (10 Feb 09 Memories in time) (13 Feb 08 Implicit and explicit memory) (15 Mar 09 Keeping echoes in mind) (11 Apr 09 Visual memory) (8 May 09 limitations of working memory) (4 Dec 09 working memory) (16 Dec 09 holding something in mind) (24 Jan 10 a bit of working memory) (10 Mar 10 phases to separate memories) (29 Mar 10 several ways of remembering) Summarized in (12 Aug 2009 property of consciousness 3)

• The focus of attention is related to consciousness. (14 Apr 09 Attention 1) (17 Apr 09 Attention 2) (16 Jun 09 attention brain waves) (17 Sep 09 awareness of the internal) (20 Sep 09 controller of alert status) (3 Apr 10 controlling attention) (30 Apr 10 the delete key) (3 May 10 Mind wandering) Summarized in (16 Aug 09 Property of consciousness 4)

Old ideas that get in the way

There are ways of thinking that interfere with understanding the brain. (12 Dec 08 a different angle) (25 Dec 09 folk knowledge)

• Some people take the metaphor between computers and brains a little too seriously. (19 Jun 08 brain-computer metaphor)

• Many people are resistance to there being a continuity between our brains and those of other animals. (4 Aug 08 are animals conscious?) (23 Aug 08 a birds eye view) (28 Oct 08 dogs) (24 Nov 08 Occams razor and rules of thumb) (12 Dec 08 hangover from the Great Chain of Beings) (27 Dec 08 not just a few animals) (19 Jun 09 anthropomorphism) (16 Jul 09 walking like a duck) (28 Nov 09 Size is not everything) (20 Feb 10 baggage2-Skinner)

• I have encountered a strict identification of language with consciousness that I think is counterproductive. (7 Aug 08 the inner voice) (24 Sep 08 unconscious meaning).

• A leftover from Freudian theories is a distrust of unconscious thinking. (6 Oct 08 bad press for unconscious) (18 Feb 10 baggage1-Freud)

• The idea that the neo-cortex is the only part of the brain involved in producing consciousness is counter production. The thalamus as well as the cortex is important in producing consciousness (11 Sep 08 Grand Central Station) (21 Dec 08 thalamus waves) (13 Dec 09 include the thalamus) (6 Jan 10 brain stem involvement in attention) (12 Jan 10 the cortex is not the hub) (7 Mar 10 turning off consciousness)

• There may be some resistance from philosophers to scientists look at an area that has until now been only examined by them. Thankfully, not a;; philosophers. (29 Jan 09 New philosophical research project) (30 Mar 09 Reductionism is necessary) (05 Apr 09 Biology and culture) (14 Sep 09 criticizing a critic of Pinker) (16 Nov 09 science and philosophy) (23 Feb 10 Baggage3-economic man) (26 Feb 10 baggage4- Descartes) (1 Mar 10 baggage5-Locke)

• But religious fundamentalists are not happy with recent developments. (12 Mar 09 Fundamentalists will challenge) (2 Apr 09 No conflict with science)

Some ‘how’ hypotheses

There are some hypotheses that seem very convincing. So far we have taken a quick look at the following:

• Bayesian calculations create consciousness. (2 Jun 08 is the brain bayesian) (24 Dec 08 Friston’s law ) looked at the possibility put forward by K Friston.

• R Rensink has a hypothesis that there are two aspects of consciousness, the big picture without detail and the focus with a few items in detail. (29 Jul 08 change)

• R Llinas puts forward a hypothesis that the thalamus controls consciousness (6 Dec 08 yet more Llinas)

• The Gaillard group and others are finding the neural correlates of consciousness. (21 Mar 09 Neural correlates of consciousness) (24 Mar 09 The global workspace) (27 Mar 09 The P3 wave) (property of consciousness 2)

• Firth has a well developed theory (1 Jun 09 what is easy and what is hard) (4 Jun 09 feeling separate from the world) (7 Jun 09 feeling separate from others) (10 Jun 09 Bayesian perception) (13 Jun 09 error signals)

• It is always a good idea (if you can do it) to understand something by reinventing it. (19 Feb 09 On the way to artificial consciousness)

• Chalmers’ epiphenomenalism is not convincing. (1 Jul 09 Emerging understanding) (4 Jul 09 Chalmers and emergence) (7 Jul 09 Chalmers and epiphenomenalism) (11 Oct 09 hard-problem mindset)

• Tononi and panpsychic theory. (10 Jul 09 a panpsychic theory of consciousness) (2 Sep 09 search methods)

• Morsella (8 Oct 09 resolving conflicting intentions) (1 Nov 09 Morsella 1) (4 Nov 09 Morsella 2)

• Fuster theory of cognit networks (31 Dec 09 Fuster’s theory of cognits) (3 Jan 10 more Fuster theory)

• Crick’s dying paper (19 Mar 10 the chaustrum)

• My own hypothesis for many years has been massively parallel overlapping feed back loops within the cortex and between the cortex and the thalamus. (4 Jul 08 ambiguous perceptions) (14 Sep 08 feedback) (25 Feb 09 A different kind of computing) (28 Feb 09 Analog computers) (3 Mar 09 A big network) (26 Apr 09 My own tentative view)

Methods and instrumentation concerns

(19 Jul 09 EEG questions) (5 Sep 09 fMRI scans astorcytes) (2 Oct 09 dead fish and voodoo) (14 Oct 09 effects of brain waves) (2 Feb 10 a decade of neuroscience) (25 Mar 10 materialism) (18 May 10 discounting science)

Miscellaneous bits and pieces

(23 Jul smell is different), (30 Aug 08 do grandmother cells fly?), (12 Oct 08 metaphor to embodiment), (27 Nov 08 not inside us), (11 Jan 09 Epistemology changes), (20 Jan 09 Proprioception), (16 Feb 09 Other definitions) (20 Apr 09 A kluge?) (8 May 09 Top down processing) (25 Jun 09 consciousness takes a lot of energy) (31 Jul 09 revisiting grandmother cells) (3 Aug 09 reading brain patterns) (30 Aug 09 innate categories) (11 Sep 09 wisdom) (23 Oct 09 fruits of introspection) (19 Nov 09 astrocytes) (22 Nov 09 a radio metaphor) (2 Dec 09 where are the concepts?) (19 Dec 09 the missing hierarchical level) (22 Dec 09 working in the missing hierarchical level) (9 Jan 10 the content of consciousness) (18 Jan 10 the big C) (25 Mar 10 a possible reason for consciousness) (27 Apr 10 the connection is important)

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