This chapter is on how elementary and multiple, and multi-directional associations of the explicit (autobiographical and semantic) kind are executed. It is given a simple approach where the general, old idea of connecting representations is simply translated into physiology as intersensory connecting of primary cortical areas/activation patterns through association areas. The basis of our so mediated complex concepts are made by the element of contrast (see chapter ‘contrast’).
The place where the elements of our thought or perception are somehow organized is the neocortex. This concerns the generally in psychological science held view, that our mental experiences like seeing a certain object or thinking a certain thought somehow take place in the material entity of the brain specified the neocortex. So it was found in research that certain perceptions parallel the activation of specified areas in the cortex.
So we know that there exists an area called primary visual cortex, another one the audio cortex, and more. These areas that somehow may be the basis of what happens when we see respectively hear something hence are distributed in the neocortex. The question is how a whole multisensory experience of the mind would be organised by these distributed, divided brain structures. For this it is important to note that even if differentiated standing for different kinds of mind experience (picture, sound,..) neurons all share basic functional attributes. These allow them to communicate nevertheless the differing experiences they mediate in the mind. Neurons of different kind can be connected with each other by synapses, through association areas. Wolf Singer found out that far away parts of the brain seem to be orchestrated by shared rhythms of firing synapses through the huge complex network of the brain (as indicated be electroencephalography). This will be prosecuted by subcortical structures namely the (gating) thalamus and hippocampus.
The brain areas of the different sensory systems are connected by shared subcortical inputs (especially hippocampus) but also within the cortex. We know that for establishing a memory the subcortical structures must be involved but they are not needed anymore later to retrieve the memory. So the subcortical activation is needed to build an independent cortical connection.
But what might happen here in concrete? How are our perceptions of the mind binded in the cortical network of uncountable interconnected neurons? Let’s assume that two patterns of different sensory type occur together in one moment. They are stimulated by and representative of two external presentations, for example a picture (seeing a tree) and a sound (rustling leaves by wind). (Find out about the element of such a pattern in the chapter ‘contrast’.) The two patterns are mediated in the respective primary cortical area of vision and sound.
Although both the specific patterns representing the two stimuli in the brain are worked by the separated and differing systems of vision and hearing they will bind in the brain as the nerve cells share characteristics of communication and connection. Connected they are cortically (association areas) and subcortically (thalamus, hippocampus).
The specific picture of a tree may be specified by a specific pattern of activation of millions of synapses in the visual system. This is made by the neuronal translation of visual features. So for example we know that synapses at borders signal stronger called lateral inhibition. Respectively the rustling-of-leaves-sound is specified by a certain pattern of activation in the hearing system standing only for this special sound.
So we know that vision and hearing are separated in the peripheral nerve system as to say on their way to the brain. So what happens is the patterns travel at a considerable speed in direction of the brain. There both, if strong enough and ‘somehow’ supported by other subcortical processes (for detail see next chapter), these complex and at the same time specific patterns of millions of nerve cells each may travel so far towards each other in the cortex that the specific more active synapses of the respective cell layers ‘find each other’ and are binded. This happens in ‘association areas’ of the neocortex mediated by so called interneurons that are able to fire and connect multidirectionally. s
So we (learn to) connect the rather co-occuring picture of tree and rustle of tree (to belong together). And we experience them together in our soul. Being together the multisensory elements of the concept tree.
The synapse is the media of elementary and multiple association. The synapse is the precondition and outcome of the association of at least 2 signals by definition. In the peripheral nervous system signals from the same sense are associated. In the brain, specific patterns of the different senses are associated by multidirectional interneurons making association areas! The elementary inscribing mechanism of synapses is called long-term potentiation and it delineates structural changes at the synapse that enhance later activation of the same connection. Important work concerning this was done by Eric Kandel and Terje Lømo.
So this might be the basis of that we experience as perceptions and their combination. So a percept might be based on the activation of according specific neuronal patterns in the brain. So if the pattern is stimulated by the simultaneous outside item in the world we call it percept. But we can also have ‘things’ in our head (mind and brain) that are not actually there at this very moment. We can have pictures in our head, we can have sounds in our head, speech, music, ... we can even ‘imagine’ movement (which might consist rather in pictures maybe connected to slight muscle activity). How does this come to form?
It was just introduced how different sensory patterns might be binded in the brain. To understand how we can have ‘things’ in mind, that are not actually there at a given moment we have to know that (as science already showed) each co-activation of synapses of neurons will at the same time leave biochemical traces at the involved synapses that will make a future ‘firing’ of all of these synapses easier and more likely. So, if one of the two patterns occurs alone - without its 'associate' from before - at a later moment in time it might be strong enough as to elicit the former accordant pattern just in the brain! Making the experience of a thought.
For example you hear the rustling of leaves on a CD and the picture of the tree will come up in your mind. The neuronal basis of this is the accordant pattern of tree stimulated in the brain by the sound of rustling alone. The excitation will go along the nerve paths trained in moment 1 (when both patterns where externally present): It will go through the association area along the interneuronal pathways towards the sensory area of its 'former' partner in the brain, and elicit the partner signal here: A signal 'in mind'! The picture of the tree as thought.
This is quite a simple principle that has been assumed thousands of years before this text is written solely by self-observation. But it is only now that we have gained the technics to specify the material basis of this as/in the brain. So the idea is just to synthesize the bioneuronal knowledge we gained with the old idea of association as for example specified by Ebbinghaus or Aristotle.
This is happening in every moment of time with some of the patterns changing at a given moments, some of them staying dependent for example if we move in our environment. And it is not only two kinds but all of our sensory inputs that come together every moment (and have to be ‘organized’ – check chapter on consciousness and concepts).
This is how our thoughts happen. And also how our concepts of all things come to be established. We learn how certain sensory attributes ‘belong’ to one entity (see chapter on concepts). Concepts are thoughts without a time domain, representing a certain 'object', the representation being established through covariation.
Thoughts can elicit other thoughts. At the beginning there is always an external stimulus. Thoughts and percepts are in a constant fluent interplay! So, we are not ‘autonomous’ of our surrounding. We are embedded and intertwined with the world around us! It is not (only) thought that makes us free (see next chapter). The world gives us hints to our thinking and also action. But the way this is happening in concrete strongly depends on what we learn (in childhood and life span). Learning has to do with positive states (next chapter).
Thoughts may be connected to and also lie in a subtle motor activation of speech muscles as thinking is also speaking to one’s self in the mind. Language exists as the association of specific motor actions of the mouth to specific concepts and is going along concept formation. The same holds for motor action in general - it's origin being reflexes - revisit 'consciousness\6'! Reading is the coupling of the concept system with additional and specific visual/graphic patterns and language. The establishment of reading and language, and motor action is also based on covariation, reward, and freedom! Securely attached infants [can] go exploring!
All of this cannot easily be followed in a [adult] person because of the huge amount of moments in a life, incoming stimuli, speed of neuronal processing and past experiences of the individual with according (re)presentations!
The statements made here greatly concern the issue of ‘localization’. Of course we know that localization exists, as we know that there are specific cortical areas for vision, movement etc.. And we know within the vision area are specified neurons to process specified picture features. So, within a sensory system in the processing neuronal layers/tissue manifold patterns (for specified ‘picture’, ‘sound’..) can be represented and processed at differing moments in time. Here it is proposed that such specified, super complex pattern of already a high number of involved cells of the different senses are interconnected by interneurons in the brain, in a way that one of them occurring alone at a later point in time will be able to elicit the fellow pattern to happen in its respective brain area, where it had been activated before from ‘outside’. More on this you find in the chapter on declarative and non-declarative memory. And the basis for this conceptualization concerning our subjective, ‘mind experience’ is elementary, and then, complex contrast within and then, between senses, as introduced in the chapter ‘contrast’. The cross-modal complex entanglement also is the ground to our concepts system constituting itself through relative contrasts (experience ‘allowed’ by highly differentiated neurons) within and between the senses.
From a strictly nature scientific point of view, what our consciousness can be made of is this what we have: senses - vision, hearing, somatosensory and interoception, smell, taste, and motor function. Combine these in complex, quickly changing patterns made by millions of differentiated yet interconnected neurons and you have a lively super complex conscious experience. A whole to be much more than just the sum of its elements. Human consciousness.