BIOLOGY

ORIGIN OF INTELLIGENT LIFE -PART -2

The weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness -D Edelman

The idea is that thanks to mirror neurons we are first able to observe  an action,then understand the underlying intention

Procedural memory and voluntary action in animals

Animals have different types of working memory in the form of modules. Thus the visual module has a hierarchy of neurons of different types,such as simple cells.complex cells,bipolar cells. Simple cells can form lines. But at edges involving intersection of lines the assymetrical input activates complex cells and they form the edges by combining inputs of two simple cells.This forms an image.Objects are recognized by a neural program. The memory of the object or its line orientation and edges from memory are enhanced in visual cortex. When a match occurs with visual input search is successfull.  

However objects require to be scanned to determine the location of lines and edges in an efficient manner reproducible from memory . The scanning sequence depends on voluntary program of eye muscles activation based on feedback correction from the environment. This is carried out by Frontal eye fields. The neurons in visual cortex are enhanced by a line or edge and sustain this over a delay period. When the actual line/edge is visualized the eye muscle motor action takes placed for the specific sequence. If the motor action is inappropriate to scan the object it fades and a new action is activated.The voluntary sequences are made in dorsolateral PFC. Succesful sequence causes joint activation and enhancement in memory. By contrast a failed sequence triggers inhibitory impulses and the sequence is not preserved in memory.

    This construction of sequences of scanning movements is initially voluntary. It is activated by the involuntary self organization in visual image formation. The voluntary action sequences if repeated many times forms an automatic procedural memory. The object is now scanned without need for voluntary enhancement and inhibition as the entire sequence exists in LTM.                                                      Attention is nothing but the enhancement of sequences of feedback voluntary actions by the Frontal eye fields..Executive control is the sequence of facilitation and inhibition of sequences based on environmental feedback and preserved in LTM  in dorsal PFC.Attention  leads to inhibition of distraction on alert response. The alert response normally shifts voluntary scanning. Inhibition of alert response allows sequences of object edges to be bound together in a single object. In planning again the alert response is inhibited till a sequence of actions are formed.

   Thinking in animals-evolutionary adaptation

Thinking is a voluntary sequence triggered by involuntary actions which require feedback from environment for completion.Animals can carry out induction,deduction ,category formation,analogy.These are carried out by  ventral medial PFC.In pigeons the visual sensory WM can distinguish colours. Morever they can arrange colours in sequences and recall them based on neurons which can detect colour differences. The attentional enhancement of the difference neurons through FEF achieves this.

    Deduction require initially category formation based on stimulus generalization. Thus coffee cups of different shapes form a category by generalization of a basic shape. Deduction occurs when categories coincide completely,partially or not at all.The difference in categories is detected by difference neurons. Deduction again requires difference detection and overlap by a voluntary sequence of attentional enhancements of FEF.Analogy is imitation. Thus movements of hitting an object can occur in different circumstances to obtain different aims.Imitation requires more effort as the production of an identical sequence  requires accurate visual feedback. Imitation is only present in monkeys and primates.

  Thinking is based on similarity detection between object and its memory map. This is done by sustained attention by inhibition of alert response. Till the time the object and its memory overlap coincide by enhancement and lateral inhibition, the alert response is inhibited. In primates this similarity detection extends to recognition in memory of object similarities between two objects. In humans action sequences and plans can be detected internally for similarity. This leads to deduction and inductive thinking.

Knowledge in animals -autonomy

Animals navigate in space by maps. These are created by deduction and inductive thinking during voluntary action.These are constructed from grid cells which lie across the field and are enhanced by objects lying in the field.Thereafter another layer  of place cells lie above it. They are enhanced by grid cells but only at particular sites in the field. The animal keeps in memory distance between objects in place cell field. During navigation the place cells are activated sequentially.

   Knowledge forms basic categories by deductive and inductive thinking.There is categorical psychological distance between categories based on differences in size,colour and these are kept in memory, During involuntary thinking these are activated by association allowing differences and similarities to be measured.Both thinking in animals and humans are dependent on innate neural networks. The plans derived from them is however acquired and preserved in PFC.

  During involuntary decision making a number of category modules based on maps cooperate. Thus distance module,reward module,effort module calculate their psychological distances to form decisions regarding navigation or social action automatically. Where a novelty occurs thinking and social modules are activated as voluntary action..They recalibrate psychological distances and modify the maps. .This makes thinking autonomous 

The orbitifrontal cortex along with amygdala automatically calculates rewards by combining contexts which have past reward associations.PFC automatically makes sequences of reward based sensations with actions Both have output to hippocampus. In animals the hippocampus uses the inputs in navigating to food sources. The function is achieved by creating maps for each action so the animals can move towards its rewards.During movement the sequence of movements have to be properly timed. If the animal abandons its plan prematurely the goal is not achieved. This is done by spectral time map analogous to space map,by the hippocampus. The animal is prevented from distraction by inhibiting all distracting events rill the goal is achieved. In image formation eye movements scan the object edges till a complete sequence occurs. During this time the alert mechanism is inhibited by amygdala reward system 

      The cerebellum is a site where actual muscle timing sequences are learned. Here also there is a spectral time map for muscle sequences which work without distraction. The basal ganglia has the largest time map. It uses unexpected rewards or punishments to create time maps. Along with PFC inputs it creates new maps of sequences based on rewards input from OFC.

Hierarchy and rule formation

  In higher animals there occurs a hierarchy of time and space maps. This allows higher map neurons to simultaneously activate multiple neurons of same class in lower networks. As a result rules are not restricted to individual encounters . Thus generalisation occur and new rules are formed. Thus ‘ Win stay,loose shiftrule’is a generalisation of outcome of many previous encounter outcomes.

Primates episodic memory and imagination- planning and stakeholder thought(Higher evolutionary adaptation)

Episodic memory is memory of events. Here spectral time map records actions carried out by self or others. This involves creating sequences of association of events.The memory of actions is peculiar to primates and apes as their hands are freed from locomotion and can carry out actions on objects.      The actions are preserved in a time map along with the rewards responsible and the outcome of the actions. All of these together constitute an episode or context.            Contexts are initially preserved in hippocampus. The hippocampus projects these time maps to medial PFC. The memory in PFC requires a time period of 24hours. The hippocampus supports LTM in medial cortex by secretion of BDNF and dopamine.

       Episodic memory leads to a unique thinking mode where thinking takes place in the mind in absence of actions. For this theFEF search mechanism has to search for memories in LTM.It takes place by contextual similarity. The search mechanism can undergo sustained attention on LTM or shift based on similarity detection. It can create planned sequences as well as deduction,induction and analogy . The similarity detection now takes place between two objects in LTM.Since the thinking is now done without external feedback networks develop which monitor self thinking ,meta cognition,probably based of time networks of rewards.

Joint attention and social learning

     In humans there evolved joint attention .  Joint attention requires ability to follows gaze of others. This allows knowledge of intention and beliefs of others and in predicting action.   This ability is possible due presence of mirror neurons in primates and more so in humans. Mirror neurons form a pictorial represention of an action sequence. Thus the act of observing a construction of a tool made object is simultaneously recorded pictorially in motor cortex.It involves automatic calculation of psychological distances to produce a picture of an event by a change in coordinates between observed distances and image construction distances.   Joint attention allows actions of others to be copied - imitation. It leads to imagination and planning. Planning involves action sequences to be created by experience from previous reward sequences. With help of Basal ganglia PFC can make a plan without being distracted. Joint attention also leads to object permanence . The beliefs of others is invariant with respect to objects and events. Thus symbols can represent actions and objects. This leads to language based on symbols. Imitation of sounds allow meaning to be transmitted both ways.

   Language is a nested ,hierarchical network of rewards ,actions and outcomes. The lower networks anticipate the words that follow one another. The higher networks anticipate clauses to form meaningfull sentences. These are examples of sequence formation  by anticipating the best response.Language is only possible if two individuals rapidly understand the rules of communication in both general case and individually.The constant discovery of new rules as enabled by language has made humans unique

    A similar sequence of social behaviour develops based on anticipation of social responses like pleasure,anger,ambition. This is based on recognition of facial ,gestural and language hints.The constant development of social rules has enabled stable society to be formed.

   Mirror neurons and categorical thought in humans(concrete operations)

Categorical thought uses deduction,induction and analogy in categorical reasoning. It arises in children by six years of age with maturity of executive enhancement and inhibition to imitate and imagine psychological distances. In human evolution it arose in homo erectus about four million years ago . This species could cooperate in hunting and communicate with gestures. In  inductive reasoning if  objects belong to different categories ,the similarity between these categories is first detected. Thereafter logical steps occur to obtain a result

        John has uric acid.

        Susan has uric acid

        John and Susan are humans

  Here the induction of both being human depends on their both having uric acid, They have a common metabolic pattern. This supracategory similarity leads to the induction of both being human.Similarly for deduction .

  Categorical reasoning requires imagination and mirror neurons.The intermediate steps in categorical reasoning requires formation of pictures for comparing similarities of categories.The intermediate steps are compared to final outcomes to see progress in .Mirror images occur spontaneously in humans. However imitation requires voluntary feedback to increase anccuracy of the image. Executive control in thinking is  the sequence of facilitation and inhibition of imaginary movements to achieve concrete comparison of similarities. This leads to induction and deduction in categorical thinking.

Mirror neurons and formal thinking

Mirror neurons allow imagination and this can be altered by. enhancement and inhibition.The creation of new sequences by altering psychological distances allows creativity and planning. Analogical reasoning requires this type of creation of scenarios with similar pattern and rules.Formal thinking leads to estimating the appropriate psychological distances in a hypothesis. It resembles giving importance to all stakeholders in a hypothesis. 

        It also leads to language where to understand spoken words requires self to imagine a scenario which is most probably is being transmitted. Language in turn allows self speech and this allows categorical reasoning much easier as the speech is allowing similarity detection,deduction ,induction to be carried out. Morever language allows instruction which enhances knowledge,The self awareness and theory of mind also depends on imagination. One understands the emotions of a fellow being by imagining his difficulties.

Formal thinking probably came with Homo sapiens about one lakh years ago. It led to cave paintings.the first religions,tribal customs.

Ack:child development(Laura A berk),The origin of mind(David c Gerry),The Wiley handbook of cognitive control,Do animals think,Mechanisms of memory(J David sweat),Working memory and language in modular mind),Brain architecture( Larry Swanson)