BIOLOGY

ORIGIN OF INTELLIGENT LIFE :PART 3

Intelligence the most plastic and at the same time the most durable structural equilibrium of behaviour is essentially a system of living and acting operations (Jean Piaget)

General working memory and its stages

Working memory can be generalized to solve universal problems. 

   This is achieved in prefrontal cortex by combining the inputs of multisensory ordered specific module working memory. Thus because prefrontal cortex receives input of ordered list of names from language working memory and also ordered list of colours from visual working memory it can make ordered list of both.In working memory sequential neurons are activated ,the initial neuron with first item the most followed by subsequent items in a list. During retrieval the first item is the one which was most active while being stored. So it is retrieved first. As the next item is activated the first item inhibits itself.

Piaget had first discovered the laws of working memory stages. The above stage where working memory can form ordered lists he called preoperational. Formation of ordered events and their recall allows episodic memory. This is present in birds, mammals and primates.

Working memory depends upon attention ,which is the enhancement of a neuron with specific orientation,colour or other property ,which enables a search for a match in the environment. In humans the search occurs in memory. After search is successfull the preoperational rearrangement of order occurs by self enhancement and mutual inhibition.

Concrete operation stage

In concrete operation stage a higher order working memory exists. This WM has neurons which store conjunctions and disjunctions based on differences of objects  properties such as length ,orientation differences.Thus the input from lower ordered lists are rearranged into classes when inputs are fed into this layer. One example is transitivity. Transitive class includes order in increasing or decreasing sequence. So an item preceding in a list is bigger than any item down the list. This class allows decisions to be made automatically of largeness once the class is idenified.Just as navigation WM depends upon landmarks and position determination to form a pathway ,similarly networks now use similarities and differences to form classes.Each problem solving  of class formation is in the form of yes and no of similarity of specific characters.This entire logical path is kept in long term memory and retrieved in WM when the path is reinitiated.Thus the transitivity class will have neurons which detect size differences,and these difference neurons form a ordered list by self excitation and mutual inhibition. 

Humans have the maximum ability to form classes. The classes include reversibility in addition to transitivity. Language involves numerous classes. Thus conjunctions like -and ,or -exist as classes in human WM.The ability to form classes allows the formation of gestural symbols. Thus a bird class may be represented by a gesture of flying made with both hands.

Formal stage

 Formal stage,present only in humans requires a separate layer of working memory. Every hypothesis has a configuration. The configuration in the most general case is a relation or proportion between the component items or classes of items. The neurons in this layer of WM is probably coding for classes of proportions such as size,weight,concentration.

An example of a configuration comprising of varying relations among incident forces and their outcome due to differences in concentration proportions comprises a hypothesis. Two examples of this hypothesis are given below where it is applied to radically different situations.

To achieve victory in battle a General makes a plan to overwhelm the castle by attacking it simultaneously by columns from multiple sides. The simultaneous concentration of military force at a single point is a configuration for success.The same configuration may be used in treatment of malignant cancer in brain .Here a single radiation of high power to burn the tumour  can damage vital structures in its path.However a simultaneous low dose irradiation from multiple directions can destroy the tumour by addition of the radiation dose at the tumour site.This spares other brain areas from collateral damage.

Semantic memory present in modern humans allows storage of information independent of their immediate utility. It depends on advancement of gestural symbols to symbols based on language word lists.Language is based on comparison and hypothesis formation.Each sentence in language is a unique combination of proportion neurons. The innate neural network of language was the basis which the formal operations could utilise to form knowledge and theoretical frameworks.

Evolution of abstract knowledge in humans

The technology of tool making is probably the most ancient of abstract knowledge. This requires planning and analogical reasoning .Such reasoning was probably present in primitive human species the homo habilis around two million years ago. This species could create gestural symbols to denote specific objects,distances and locations.It could understand crude stone tool chipping sequences and teach them to others.

  The subsequent species of humans,homo sapiens probably arose around one lakh years ago. It had more formal operation abilities and construct narratives based on symbolic word sequences. The transmission of narratives and knowledge created an explosion in human technology as social knowledge increased in volume. Thus cave paintings,narrative history ,new Stone Age finely chipped stones were invented.

Epigenetic and genetic  basis of human mind

The presence of multiple levels of working memory may possibly be due to gene duplications and subsequent mutation or recombination events .Humans show a huge number of network modules which is well beyond the memory available  in genes to encode them. The innate modules like for language.social recognition  have inbuilt predispositions to associate the items pertaining to them. One epigenetic mechanism may be alternate RNA splicing. Alternate RNA splicing can produce multiple RNA configurations by rearrangement of nucleotides. These then code for alternate proteins that make a neuron unique in its predisposition to items.

Hierarchy formation

The nervous system has developed a hierarchical network during evolution. The lowest level is that consisting of innate networks ,reflex coordination between these networks. However with development of special sensory organs of vision ,smell they are controlled by the brain . The brain inhibits most automatic actions and it uses working memory to determine appropriate action such as in navigation.In mammals working memory is under control of emotions. Emotions are a set of autonomic and motor actions such as attachment , revulsion. They are produced by networks in limbic system in brain and lead to sustained behaviour in the absence of conscious attention and hypothesis formation. In humans emotions frequently come in conflict with deliberate thinking. This can result in anxiety depression and other psychosis

Ack:Do animals think,The cradle of thought,Origins of intelligence,Fundamentals of cognitive neuroscience,Child development(Laura bark)