News

New reviews of papers, articles, books etc.

1.) i of the vortex - Llinas, R. - added 9 September - Good discussion of gamma synchrony, gap junctions and self-generation of activity within the brain. (Under General Articles 7 and Mainstream 3

2.) The Structure of Thinking - Laura Weed - added 5 September 2008 - Challenges the mainstream of 20th century  philosophy regarding the functioning of the mind. (Under Key Articles: 3)

2.) Three Roads to Quantum Gravity - Lee Smolin - added 29 August 2008 - Close to Penrose in his view of spacetime

3.) Science & Poetry - Mary Midgley - added 4 August 2008 - Criticisms of mainstream ideas on consciousness

4.) Critique of Heterophenomenology - Christian Beenfeldt - added 8 August 2008 - Attacks Dennett's arguments for treating first-hand experience as fiction.



Other recent reviews:
1.) Making up the Mind - Chris Frith - 29 August (2.)  Conscious Mind - David Chalmers (Under  General Articles:5) (3.) Wider than the Sky - Gerald Edelman - 23 July (Under Mainstream: 3)  (4.) The Goldilocks Enigma - Paul Davies (under General Articles: 4)   (5.) The Astonishing Hypothesis - Franci Crick  (under Mainstream: 3   (6.) The Quantim-Like Brain - Andrei Khrennikov  (under Other Quantum)  (7.) Descartes Error - Antonio Damasio - 7 July (under General Articles 4)  (8.) Mind-Like Universe - 2 June - (under Cosmology and Key Articles) 
 

i of the vortex

Llinas, R.

New York School of Medicine

MIT Press  ISBN  0-262-12233-2

Llinas argues that much of the activity of the brain is intrinsic or self-generated, with sensory input seen as coming in on top of, and modulating, existing brain activity. The brain is suggested to be a closed system, with sensory input being more about specifying cognitive states than actual information. In this system, sensory cues are incorporated into on-going cognitive states. The more conventional image has been of a passive brain only performing when it receives sensory input.

Electrical oscillation

The author’s major emphasis is on the electrical oscillations in the brain. He describes how the electrical potential across cell membranes is subject to an intrinsic small oscillation. He likens this to gentle ripples on a pond. On occasion, much larger fluctuations arise. These are known as action potentials, and form the basis of communication between neurons. The intrinsic oscillation of a neuron can influence its responsiveness to incoming signals. Llinas regards electrical oscillation as the glue that allows the brain to organise itself. He stresses that simultaneity of neuronal activity is pervasive in the brain, and that this derives from neuronal oscillation. It is suggested that neurons that display rhythmic oscillation may entrain each. Neurons which oscillate in phase (with the peaks and troughs at the same time) can support simultaneity of operation. Llinas uses the example of cicadas that chirp in rhythmic unison because they have an internal clock, which is an intrinsic oscillator. Fluctuations within this rhythm constitute information that is available to individuals or cells remote from one another. Oscillation in phase so as to make scattered elements work together in amplified fashion is known as resonance. A group of neurons that resonate with each other may also resonate with another group that are in an area of the brain remote from them. However, not all neurons resonate at all times. Neurons are able to switch in and out of the oscillatory mode and this allows resonance to occur transiently among different group of neurons. Cells receiving new sensory information may start to resonate with other groups of neurons. Llinas’s own work has uncovered the existence of intrinsic neuronal oscillations and the ionic currents that generate them⁽¹⁾. This is related to membrane conductance, and it has been shown that neurons are capable of generating action potentials without the presence of external input⁽²⁾.

 

Llinas argues that the brain is a closed rather than an open system. By an open system, he means one that is a reflex that merely receives, processes and outputs data, rather than contributing anything of its own⁽³⁾. The closed-system hypothesis that Llinas favours argues for a mainly self-activating system generating its own intrinsic images. Sensory input only gains significance as a result of the pre-existing state of the brain.

Llinas considers that our understanding of the external world arises from the juxtapositioning of internally generated images with the sensory properties of the external world. The internal images occur through intrinsic properties of the brain. Llinas develops this idea as an explanation of the process of dreaming. Dreams derive from intrinsic activity of neurons. In REM sleep, the brain is not receptive to sensory signals, but only to its intrinsic activity⁽⁴⁾. Studies by Llinas himself⁽⁵⁾ show that 40 Hz activity is present both in the awake condition and in REM sleep, but is greatly reduced during deep sleep, which is characterised by delta waves. In the waking state, auditory signals produced a change in the 40 Hz oscillation, but in REM sleep, there is no change in the oscillation. The significant thing is that in REM sleep the brain is so adjusted as to carry on with its intrinsic or internal activity, and to ignore sensory input.

Interneurons

Interneurons are particularly important in Llinas’s view of the brain. An interneuron is defined as any neuron that does not communicate with the outside world, but only exchanges information with other neurons. The interneurons serve to distribute sensory input to various components of the brain. The interneurons are thus in a position to influence a large number of other neurons and in effect ‘steer with multiple reins’. A particularly sensory input may stimulate a relatively small number of cells, which may activate another small number of interneurons, which then go on to have widespread effects. Interneurons are found throughout the central nervous system and particularly in the thalamocortical areas. Llinas’s emphasis on the intrinsic or internal activity of the brain also leads to him being opposed to the tabula rasa view of the brain as a blank slate at birth ready to be entirely determined by subsequent conditioning. In support of his view, he quotes studies⁽⁶⁾ in which newborn monkeys respond differently to lines of different orientation, although they had never previously seen lines.

 

Gap Junctions and Gamma Synchrony

Llinas emphasises the importance of gap junctions in the operation of the brain. In addition to the synaptic connections between cells, which involve a neurotransmitter crossing a 20 wide nanometre gap, the gap junctions offer a quicker and more direct connection. Unlike the synapses that require a chemical signal, the gap junctions allow ions to move from one cell to the next, and this constitutes a form of signal transmission that is quicker than the synaptic kind. Moreover, cells that receive such an ion based signal may be activated to fire an action potential. This can result in rapid and synchronous firing of interconnected cells. This allows a group of neurons to fire synchronously, as a result of which other more distant groups may resonate with them in a synchronous signalling pattern. This rapid electric coupling produces simultaneity between many neurons or in Llinas’s words creates the ‘roar of the masses’ rather than a ‘voice in the wilderness.’ This is effectively Llinas’s solution to the binding problem. The synchronous activity of group of neurons at locations remote from one another in the brain combines information from disparate sources and modalities. Llinas suggests that the effect of resonance is to bind together the spatial related processing of different groups of neurons at the same time. He implies rather than says that this accounts for the ‘now’ or ‘present moment’ sensation that is so much a part of consciousness, but which conflicts with special relativity. Llinas points to the example of the electric shocks delivered by electric eels. The motor neurons involved in delivering the shock have axons of varying length depending on their distance from the point from which the shock is administered, arranged so that the charges are delivered simultaneously, without which they would be of little effect. In a similar way, activity in the central and peripheral parts of the human retina is almost synchronous when it subsequently arrives at the thalamus.

 

These ideas are supported by a series of studies^(7-9) showing widespread synchronicity in the cortex. Synchronous activity in a single column in the visual cortex is observed when particular light bars are presented, This involves gamma (around 40 Hz) oscillation, and this can resonate between different cortical columns, and between regions of the cortex separated by as much as 7mm. The studies show that there are spatially separated ensembles of neurons bound together by an oscillation of around 40 Hz. Studies also indicate that 40 Hz coherent neuronal activity is generated during cognitive tasks. Some proposals suggest that this reflects the resonant properties of the thalamocortical system^(10-14). This coherent activity is a candidate for the unitary binding of sensory perception and thus the unity of consciousness. However, Llinas envisages this as a machine that is constantly ‘humming’, not something that is only switched on when it receives sensory inputs. The 40 Hz oscillation has a high degree of spatial organisation, and its synchronous oscillation may also be capable of producing the temporal conjunction of separate resonating groups of neurons.

Further evidence for the intrinsic or internal quality of much brain activity is seen in the fact that the input that the thalamus receives from the cortex is much larger than its input from the sensory systems. Neurons with intrinsic oscillation situated in the thalamocortical areas are suggested to allow the brain to self-generate oscillatory states that shape the impact of sensory stimuli. The hub position of the thalamus in the brain allows the thalamic nuclei to link to all parts of the cortex. In particular, the association areas of the cortex, which are very large in the human brain, receive input from both the association nuclei of the thalamus and from the sensory cortex. Llinas sees the thalamus as synchronously relating the sensory input from the external world with internally generated ideas and memories.

 

Consciousness

Llinas’s book repeatedly emphasises the workings of the brain in relation to in relation to the mechanical activity of muscles, their supporting motor neurons and the relevant parts of the cortex. This is not to deny the importance of these areas, but it is arguable that this emphasis facilitates an ultimately unhelpful approach to the problem of consciousness. From the point of view of students of quantum consciousness this is a pity, because Llinas penetrates further than most neuroscientists into the question of gamma synchronisation and gap junctions, bringing him close to the views of Hameroff.

 

This is an important book because of its argument for the self-generating nature of much of the activity in the brain, and for the role of the gamma synchrony relative to this self-generating nature. Llinas’s insight that the gamma synchronisation across spatially remote groups of neurons may correlate with the ‘now’ sensation of consciousness has explanatory value. Unfortunately, he does not go the further step of producing a mechanism that explained why this correlated activity produces subjective experience rather than unconscious information processing. His description of brain function in respect of the gamma synchrony and the gap junctions bears an extraordinary resemblance to their role the Penrose/Hameroff Orch-OR model of consciousness. This might have sparked an interesting chapter on the possibility of quantum features. However, Llinas doubts that this scenario is worth pursuing seriously. Why does he think this? In the course of a rather wordy paragraph, he comes round to the conclusion that electrical patterns are the same as qualia. This is simply stated as a belief with no plausible reason given, and the matter is simply left at that.

 

We have to be specific about what Llinas appears to be trying to say here. He is not claiming that electrical oscillations are connected or correlated with qualia in some way but that they are the same thing as qualia. But this gives rise to the problem as to why it is only the electrical patterns in the brain, and only some of those that are conscious and have subjective experience. Elsewhere, he has given a good description of how the electric potential across the cell membrane works in principle in the same way as a battery, but Llinas does not presumably think that batteries are conscious. While brain activity is no doubt related to conscious, there is a requirement to show why these functions produce the property of consciousness or qualia not found elsewhere in the physical universe. Llinas could have attempted an explanation based on complexity or information processing. As far as he will go in this direction is to argue that the process of muscular movement is somewhat similar to the process of producing sensations in the brain. He is probably right in saying that the physical mechanisms are similar, but this does not really bring us any closer to why one class of these mechanisms is especially involved with subjective sensory experience.

 

References:-

 

1.) Llinas, R. (1988)  -  Insight into the central nervous system function  -  Science, 242, pp. 1654-64

 

2.) Hutcheon, B. & Yarom, Y. (2000)  -  Intrinsic frequency preferences of neurons  -  Science, 242, pp. 1654-64

 

3.) Llinas, R. (1987) - Mindness  -  In: Mind Wave, Eds. Blackemore, C. & Greenfield, S.

 

4.) Llinas, R. & Pare, P. (1991)  -  Dreaming and wakefulness  -  Neuroscience, 44, pp. 521-35

 

5.) Llinas, R. & Ribary, U. (1993)  -  40 Hz oscillation characteristics of dream states in humans  -  Pub. of the National Academy of Sciences, USA, 90, pp. 2078-81

 

6.) Hubel, D. & Wiesel, T. (1979)  -  Orientation columns in the striate cortex  -  Journal of Comparitive Neurology

 

7.) Eckhorn, R. et al (1989)  -  Coherent oscillations: A mechanism of feature linking in the cortex  -  Biol. Cybern, 60, pp. 121-30

 

8.) Gray, C. & Singer (1989)  -  Stimulus specific oscillations in orientation columns  -  Proceedings of the National Academy of Science, USA, 86, pp. 1698-1702

 

9.) Gray et al (1989)  -  Inter-columnar synchronisation  -  Nature, 338,  pp. 334-7

 

10.) Llinas, R et al (1991)  -  Intrinsic oscillatory activity  -  Proceedings of the National Academy of Science, USA,  88, pp. 897

 

11.) Steriade, M. et al (1991)  -  20-40 Hz oscillations in the thalamocortical system  -  Proceedings of the National Academy of Science, USA,  88, pp. 4396

 

12.) Whittington, M. et al (1995)  -  Synchronised oscillations in interneuron networks  -  Nature, 373

 

13.) Steriade, M. & Amzica, T. (1996)  -  Intracortical and corticothalamic coherency of fast oscillations  -  Proceedings of the National Academy of Science, USA,  93, pp. 2533-38

 

14.) Steriade, M. et al (1996)  -  Synchronicity of 30-40 Hz oscillations in the thalamocortical network  -  Journal of Neuroscience, 16, pp. 2788-2808

The Structure of Thinking

Laura Weed

Dept. of Philosophy, College of St Rose

Imprint Academic (2003)  ISBN  0 907845 27 4


The author argues that the underpinnings of much of 20th century philosophy are unsound. This includes philosophers such as Dennnett, whose thinking has been a central theme in modern consciousness studies. She suggests that Dennett has relied on and expanded from flawed premises. She queries the assumption of many modern philosophers that symbolic logic, computational mathematics and experimental science can explain all that exists. She argues that this has left science/philosophy with too few tools for understanding the brain and the mind.

Her criticism of strong AI (artificial intelligence) is that its proponents are only looking at the products or results of thinking. The author, however, wants to concentrate on what the knower knows. She views this as an interactive relationship between mind and world. She argues that the process by which one acquires knowledge of particular objects is different from the process of acquiring concepts about these objects.

In this book, the acquisition of knowledge is referred to as ‘x’ and the development of the concept as ‘y’. She refers to ‘x’ as ‘object positing’ and ‘y’ as ‘property attribution’. She thinks that these processes can be analysed separately, although they often operate in tandem. The ‘x’ object positing process involves the identification or recognition of particular features. Object positing usually involves direct perception or direct experience. The ‘y’ property attributing capacity deals with sorting, qualification and quantification. The two types of mental processes, object positing and property attributing, together comprise the mental processes, by which we interpret the world.

The author’s objection to strong AI is that it lacks any object positing, and works only at the level of property attribution. The ‘x’ process incorporates the ‘passing show’ of the world, and the ‘y’ process comprises the computational structures that work on the raw data of experience. The ‘y’ process of computational structuring taken by itself does not work, because it lacks the raw data on which to work. Similarly the passing show does not mean much without the structuring work of the ‘y’ processes.

 

The ‘x’ and ‘y’ distinction is not new in philosophy, but it is against the grain of 20^th century philosophy, which has tended to base theories on the ‘y’ process, and to work hard to squeeze out the ‘x’ process of first person experience. The price of this has been to exclude what actually happens in the world.

The author particularly attacks the work of the behaviourist philosopher W.V. Quine, who argued that if the reports of different observers agree, their public report takes priority, and private reports are of no significance. This is his justification for ignoring the ‘x’ process. Further, Quine, as a behaviourist, sees the personal experience as inaccessible to investigation and therefore worthless. Quine thinks that the senses need to borrow concepts of objects from elsewhere, while the author argues that an object impinges directly on the senses. It would however seem that the public report favoured by Quine is in fact comprised of a series of private reports, without which it would not exist. The author notes that the philosopher, John Searle, has argued that the fact that there are difficulties with investigating private experience does not mean that private experience does not exist. Both the author and Searle take the further view that even if we had the exact biochemical correlates of experience, the experience itself would remain private. For instance, even if we had the exact correlates of the radar experience of Thomas Nagel’s bat, we would have no idea what its radar experience felt like.

 

The author goes on to discuss her view of causation, which she characterises as ‘kausation’ to distinguish it from other theories of causation. In this, the observer is in direct contact with the external world, and at the same time is identifying and naming various aspects of experience. The author makes a further distinction between ‘x’ as the mind side of the process, and ‘r’ as the external world or reality side of the relationship. The subject identifies some external object as the source of their experience. She sees ‘x’ and ‘r’ as effectively identical, although separable for purposes of discussion. ‘x’ is the experience of an object. The object has meaning for the experiencer. This is the intentionality, or the ‘aboutness’, or ‘ofness’ of an experience, and this is something only possible for an entity with a point of view. In speaking of something with a point of view, the author presumably refers to conscious entities.

The author goes on to provide a diagram to further clarify her reasoning. She says that an aspect of reality 'r' impinges on a person 'P' kausing the experience 'x'. The person 'p' takes the view that their experience has been 'kaused'. P recognises 'x' as an experience 'r'. P names 'r' as the kause of the experience 'x' and identifies 'r' with the notion of the experience 'x'.  The author contrasts her position with that of Searle. He sees it necessary to introduce agency to explain perception or experience, while the author sees experience as something that must be exported to agency.

Some critics consider that a percipient’s brain requires a concept of a thing before it can perceive it. The author sees the brain as more active, with perceivers focusing attention and thence creating an ‘x’. Parts of the philosophical tradition have problems with the supposed concept of action at a distance in the percipient recognising a separate object, but the author argues that sensory inputs from light and sound are in principle no different from sensations from within the body. Sensory awareness should not be seen as less direct than bodily sensation and the idea of an external/internal split in the processing of sensory inputs is criticised as artificial.

 

Helen Keller

The author comments on the famous case of Helen Keller. For her words were initially just a game, but she suddenly grasped that the ‘x’ experience of pressing certain symbols was linked to the experience of washing. The author’s point is that it needs an entity that has experiences, to link one experience to another. A computer that didn’t have experiences could never link the typing of particular symbols to the experience, as distinct from the knowledge of the washing function. This is seen as similar to Searle’s Chinese room where he maintains that number crunching or symbol processing does not equate to understanding.

 

20^th Century Philosophy

Russell and other 20^th century philosophers held that the concept of sense data was distinct from the actual sensation. Russell thought that colours and sounds were sense data that were distinct from the actual sensation of seeing a colour or hearing a sound. In his theory, the colour itself is a sense datum, not a sensation. Thus Russell saw the territory as being split three ways between the physical object, the sense datum and the final sensation. In particular, he thought it necessary to have a sensation/sense data split, to distinguish between the act of perception and the perception itself. This sense datum turns out to be a process of logical inference, by which the subject determines the nature of object placed at a distance. However, this sense datum is not required for internal bodily processes.

This approach remained unchallenged during much of the 20th Century. The author highlights three features of the 20th century orthodoxy. Firstly there was  a strong distinction between the nature of sensations from the body, and the nature of sensations from the external world that were viewed as problematic. The external world is suggested to require separate data for sensations to be created that are not necessary for the internal world. Finally, the external sensations are judged to be objectively real, whereas the internal sensations are viewed as subjective and therefore not properly real.

 

Hidden Agenda

The author suggests that there are several assumptions concealed in this orthodox view of perception that she thinks these are false. She sees no reason to believe that sensing external objects is more problematic than sensing pains in the body, and therefore she sees no requirement for a sense datum in the former case. She does not agree that it is necessary to have a system of logical inferences in order to identify an object. The author argues that the psychological literature suggests that humans are just as well equipped to detect external objects, as they are states in their own bodies. In principle, she argues that there is no great difference between detecting an object in your locality, and detecting a blister on your toe. In both cases, attention diverted elsewhere could lead to a sensation being missed or misidentified.

Psychological research

The author goes on to examine some recent psychological research felt to support her arguments. Studies demonstrates that three operations are performed continuously by both the eyes and ears, which are segregation of objects from their background, determining distance and determining motion. The figure/background distinction applies if there are stimuli from more than one region. The figures rather than the background are the objects of interest. Interest is a crucial factor. The author sees interest in things as a prime distinction between humans and computers. Computers are much more efficient than humans for particular tasks, but they are not viewed as being interested in the task, or having any intentionality (feeling of the task being about something). Further to this some aspects of sensory performance such as the sensation of depth are directly linked to the nervous system. Another experiment, involving young children judging distance, showed that the majority of infants could judge that a larger/distant box was larger than a nearer/smaller box, despite the fact that the nearer/smaller box cast a larger image on the retina. The author argues from these examples that there is no separate sense data or logical inference machinery involved in perception. The last experiment demonstrates a built in or hard wired perspectival system in the brain. She further points out than some suggestions for logical inference structures in sensing the world rely on Euclidean space rather than perspectival structures now supported by experiment. These features suggest that perception is a spontaneous or hard wired feature, not requiring a sense datum or a process of logical inference. The author sees the perceptual act as directly tied to the nervous system. In being so tied, it is exactly the same as internal sensations of pain etc.

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