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LINKS: ....Bird Flu Info ....Your Memory Enhancer ....Neurotech ....Success Tips ....Free Feelings and EmotionAre there any more layers to the brain above learning? Or is learning itself differentiated into layers, at least in terms of circuit design? Both birds and mammals use learning, but these split from a common reptilian-type ancestor over 300 million years ago. So, if learning circuits only evolved once they should be in the ancestor. We know mammals evolved smarter brains since then, but so did birds, and we are not sure if advanced learning circuits evolve separately in birds. Birds have a form of learning called mimicry or imprinting. This might have evolved separately from how learning circuits of mammals evolved, but it is equally likely that mimicry is a more primitive form of learning, evolved in the common ancestor. As we shall also see learning takes at least two forms physically. One is the wiring of the inter-neurons in ways that can be altered after birth, but there is also "memory" at a synaptic joint where wires are connected to other neurons. Synaptic or "memory" learning is probably very primitive, and already exists in purely reflexive brains like those of fish or reptiles. On the other hand, the common reptilian ancestor of birds and mammals might have evolved at least "wire once" learning circuits, which allow "one time" learning after birth by mimicry or imprinting. In this case there would also be in mammalian brains "wire once" learning circuits although it is not obvious what their exact modern functions is. Still, the unique learning circuit mammals possess is the "wire many times" one, which provides a capacity for learning out of all proportion to anything more primitive brains possess. The other permutation to learning is what the learning circuits would be connected to. Learning circuits of a "wire once" or "wire many times" type will not allow much learning if they are only connected to fixed wiring reflex neurons. But once learning circuits are connected to each other, learning possibilities multiply rapidly. This is how the "wire many times" circuits might have evolved. In birds say, it seems that the "wire once" circuit can be triggered at different times in the bird's life, probably on an instruction from a fixed neural circuit. But once the "wire on command" neural circuit separated from the fixed circuit to become connected instead to another learning circuit, the learning process itself becomes more independent of the genetic instruction. Whatever the case, in human brains we get massive interconnection between "wire many times" learning circuits larger than any other form of neural connection. This allows for both thinking and learning which is reflective (rather than reflexive), to an extent of allowing 'learning about learning' and 'thinking about thinking' which has become the hallmark of our species. Significantly in all this, human DNA is only 1-2% different from chimp DNA. So, considering the other anatomical differences between chimps and humans, probably not much of the DNA variation goes into neural designs as such, apart from specifying a recipe of a huge number of interconnected "wire many times" neural learning circuits. Only now we come to an attribute of learning circuits often overlooked. It has been described how sensation is a form of motor response existing in the lower brain, and so circuits producing sensation are available first before learning circuits evolve. Nature is an efficient designer, but especially with respect to neurology. So if circuits producing sensation already exist there would be no need to reinvent them once learning circuits arrived. This would be especially true if sensation circuits were hardwired reflex and saturation of genetic instructions for producing reflexive neural design caused learning to arise anyway. Also, as learning is a more versatile and advanced circuitry, nature is certain to build learning as one more 'layer' over the top existing structure, as it did in every other advance, utilizing at a lower level what was already there. This infers that even though learning circuits produce sensation, but especially more abstracted sensations of mood, temper, and affection, the learning circuits themselves are not inherently "sentient". Rather, the learning circuits of the upper cortex are tied through inter-neurons to those producing "sensation" in the lower brain. For example, in the human brain the thoughts of the higher cortex, the cerebrum, produce emotional responses in the limbic system, which is a lower earlier evolve layer. But physical response of muscle twitch or release of chemicals is possibly in lower, earlier evolved layers, such as the pons or thalamus. This peculiarity of neurology of where the physical response is produced complicates how we explain emotions such as moral feelings, and how a person responds to behaviors acquired by learning. The process is; 1. A stimulus enters through the more primitive brain, 2. It moves up through brain layers to as high as learning, and provokes a learned response. 3. This response triggers a sensation back in a primitive segment of the lower brain. We will call the history of a stimulus impinging on the senses, until its final response in the motor circuits, a transaction. Now in primitive animals without learning transactions will be indistinguishable from reflex. We suppose that for two animals of the same genome, without learning; * Identical stimulus will cause identical reflex * Identical stimulus will cause identical transactions. But for animals from the same genome but with learning; *Identical stimulus will cause identical reflex *Identical stimulus could cause different transactions. Lion cubs raised in captivity must be re-taught to kill in the wild. So even for a wild cub and domesticated cub taken from the same litter identical stimulus could cause different responses, and hence different transactions. Just as in humans, violence might cause very different reactions in a soldier to a priest, and so on. Only with learning while the input reflex might be identical the output reflex might be different, depending on how learning circuits routed a learned segment of the transaction through the higher cortex. Thus, two individuals with learning might "feel" different moods from identical circumstances. This in turn complicates moral theory, when we examine why people 'react' in an allegedly programmed way to ideas or suggestions. As encephalization evolves however, one more component of neural machinery is required, which we will call "transfer circuits". These supervise encephalization. They ensure that learning circuits, which are modifiable, work as reliably under stress as do the solid "hard-wired" circuits of reflex. Encephalization is an efficient strategy but it means transferring crucial behavioral functions to more recently evolved, self-learning circuits, whose phenotype behavior will not be directly controlled by the genotype. This will require one more circuit controlled by the genotype, to control the learning circuits. Little research has been done on this, so for now the existence of "transfer circuits" is only logically inferred. But if they do exist transfer circuits could more logically explain a genetic basis to moral feelings and leaning injunctions, than could other theories. We will return to this issue when we discuss theories of morality. To summarize then, brain, mind, consciousness, intelligence, moods, and feelings are all complex phenomena, which need explanation. Yet, none of these are in any way metaphysical in that they cannot be explained in evolutionary terms. We see the brain building up anatomically in layers with each new evolutionary strategy, and each new layer bringing into existence new forms of consciousness. HOME...... Brain Food LINKS: ....Medical Dictionary ....Stress Management ....Allergy Info |