Introduction to Cognitive Neuroscience

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Introduction to Cognitive Neuroscience
Cognitive Architectures
Based on book Cognition, Brain and Consciousness
ed. Bernard J. Baars courses taught by Prof.
Randall O'Reilly, University of Colorado,
and Prof. Wlodzislaw Duch, Uniwersytet Mikolaja
Kopernika and http//wikipedia.org/
http//grey.colorado.edu/CompCogNeuro/index.php/CE
CN_CU_Boulder_OReilly http//grey.colorado.edu/Com
pCogNeuro/index.php/Main_Page
Janusz A. Starzyk
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• from the brain, and from the brain alone,
  arise our pleasures, joys, laughter and jokes, as
  well as our sorrows, pains, grief's and tears.
  Through it, in particular, we think, see, hear,
  and distinguish the ugly from the beautiful, the
  bad from the good, the pleasant from the
  unpleasant
• Attributed to Hippocrates, 5th century BC

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The Brain ...

• The most interesting and the most complex object
  in the known universe
• How can we understand the workings of the brain?
  
• On what level should we attack this question? An
  external description wont help much.

• How can we understand the workings of a TV or
  computer?
• Experiments wont suffice, we must have an
  understanding of the operating principles.
• To verify that we understand how it works, we
  must make a model.

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How do we know anything?

• An important question how do we know things?
• Examples super diet based on dr. K, Chinese
  medicine
• and other miracle methods. How do we know that
• they work? How do we know that they are for real?

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How to understand the brain?

• To understand reduce to simpler mechanisms?

• Which mechanisms? Analogies with computers? RAM,
  CPU? Logic? Those are poor analogies.
• Psychology first you must describe behavior, it
  looks for explanations most often on a
  descriptive level, but how to understand them?
• Physical reductionism mechanisms of the brain.
• Reconstructionism using mechanisms to
  reconstruct the brains functions
• To create what must we know in order to create
  an artificial brain?
• We can answer many questions only from an
  ecological and evolutionary perspective why is
  the world the way it is? Because thats how it
  made itself ... Why does the cortex have a
  laminar and columnar structure?

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From molecules through neural networks
10-10 m, molecular level ion channels, synapses,
properties of cell membranes, biophysics,
neurochemistry, psychopharmacology
10-6 m, single neurons neurochemistry,
biophysics, LTP, neurophysiology, neuron models,
specific activity detectors, emerging.
10-4 m, small networks synchronization of neuron
activity, recurrence, neurodynamics, multistable
systems, pattern generators, memory, chaotic
behaviors, neural encoding neurophysiology ...
10-3 m, functional neural groups cortical
columns (104-105), group synchronization,
population encoding, microcircuits, Local Field
Potentials, large-scale neurodynamics, sequential
memory, neuroanatomy and neurophysiology.
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to behavior
10-2 m, mesoscope networks sensory-motor maps,
self-organization, field theory, associative
memory, theory of continuous areas, EEG, MEG,
PET/fMRI imaging methods ...
10-1 m, transcortical fields, functional brain
areas simplified cortical models, subcortical
structures, sensory-motor functions, functional
integration, higher psychic functions, working
memory, consciousness (neuro)psychology,
psychiatry ...
Cognitive effects
Principles of interactions
Neurobiological mechanisms
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to the mind
Now a miracle happens ...

• 1 m, CNS, the whole brain and organism
• An interior world arises, intentional behaviors,
  goal-oriented actions, thought, language,
  everything that behavioral psychology examines.
• Approximations of neural models
• Finite State Machine, rules of behavior, models
  based on the knowledge of cognitive mechanisms in
  artificial intelligence.
• What happened to the psyche, the internal
  perspective?
• Lost in translation neurons gt networks gt
  behavior

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to the mind
What if we were magically shrunk and put into
someones brain while he was thinking. We would
see all the pumps, pistons, gears, and levers
working away, and we would be able to describe
their working completely, in mechanical terms,
thereby completely, describing the thought
process of the brain. But that description would
nowhere contain any mention of thought! It would
contain nothing but descriptions of pumps,
pistons, levers! - Gottfried Leibnitz 1690
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Levels of description
Summary (Churchland, Sejnowski 1988)
Sensing outside and inside the body
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Distance from 10-10 m to one meter

• Small molecules can change brain functions and
  resulting behavior.
• Around year 1800 people were surprised to find
  out that nitrous oxide (N2O) changes their
  behavior it produces small amount of
  neurotransmitter.

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Time scales - 10 orders of magnitude

• Neurons can fire as fast as 1000 Hz.
• Our brain deals with events on the time range
  from years to milliseconds.
• 100ms is about the fastest we can react to an
  event.
• Slower reaction time would prevent humans from
  protecting themselves from dangers and they would
  have no chance to survive and reproduce,
• faster reaction time would overwhelm the brain to
  combine sensory inputs and determine the
  direction and speed of the attacker.
• Some skills take long time to master like playing
  guitar or learning how to speak.

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Making Inferences

• Inferences - explanatory concepts from raw
  observations
• - play an important role in science.

• Figure showing relation between observations
• lights seen in the sky, and the inferences
  drawn,
• path of the planets around the sun.

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Working Memory
Working Memory

• Observations, based on experimental data, are
  important in cognitive science.

• Concepts like working memory and their size
  (7/-2) are not given in nature but are
  inferred from experimental observations.
• Emerge from years of testing, working memory
  proposed after a 2 decade study of immediate
  memory

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Working Memory Models

• EEG (Electroencephalography), fMRI (Functional
  Magnetic Resonance Imaging), etc are inferential
  measurements of brain.
• Results for working memory
• converge well with
• behavioral measurement.

• Combined sources of evidence are widely used for
  study in cognitive neuroscience

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Neurocognitive Models

• Computational cognitive neuroscience detailed
  models of cognitive functions and neurons.
• Neurocognitive computing simplified models of
  higher cognitive functions, thinking, problem
  solving, attention, language, cognitive and
  behavioral controls.
• Example models
• Self-organization, dynamic net or biophysical
  spiking neurons.

Lots of speculations, but qualitative models
explaining the results of psychological
experiments as well as the causes of mental
illnesses are developing quickly. Even simple
brain-like information processing yields results
similar to the real ones! Warning against
excessive optimism based on behavioral models.
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Model of self-organization

• Topographical representations in numerous areas
  of the brainsensory impulses, multimodal maps
  of orientation, visual system maps and maps of
  the auditory cortex.

Model (Kohonen 1981) competition between groups
of neurons and local cooperation. Neurons react
to signals adjusting their parameters so that
similar impulses awaken neighboring neurons.
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Dynamic model

• Strong feedback, neurodynamics.
• Hopfield model associative memory, learning
  based on Hebbs law, synchronized dynamics,
  two-state neurons.

Vector of input potentials V(0)Vini , i.e. input
output. Dynamics (iterations) Þ Hopfields
network reaches stationary states, or the answers
(vectors of elemental activation) of the network
to the posed question Vini (autoassociation).
If the connections are symmetrical then such a
network trends to a stationary state (local
attractor). t discrete time.
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Advantages of model simulations

• Models help to understand phenomena
• enable new inspirations, perspectives on a
  problem
• allow to simulate effects of damages and
  disorders (drugs, poisoning)
• help to understand behavior
• models can be formulated on various levels of
  complexity
• models of phenomena overlapping in a continuous
  fashion (e.g. motion or perception)
• models allow detailed control of experimental
  conditions and exact analysis of the results
• Models require exact specification of underlying
  assumptions
• allow for new predictions
• perform deconstructions of psychological
  concepts (working memory?)
• allow to understand the complexity of a problem
• allow for simplifications enabling analysis of
  a complex system
• provide a uniform, cohesive plan of action

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Disadvantages of simulations

• One must consider limitations of designed models
• Models are often too simple, they should
  contain many levels.
• Models can be too complex, theory may give
  simpler explanation
• why there are no hurricanes on the equator? -
  due to Coriolis effect
• Its not always known what to provide for in a
  model.
• Even if models work, that doesnt mean that we
  understand the mechanisms.
• Many alternative yet very different models can
  explain the same phenomenon.
• Models need to be carefully designed to fit the
  observations
• Whats important in building a model are
  general rules
• the more phenomena a model explains, the more
  plausible and universal it is.
• Allowing for interaction and emergence
  (construction) is very important.
• Knowledge acquired from models should undergo
  accumulation.

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Cognitive motivation

• Although the thinking process seems to be
  sequential information processing, more detailed
  models predict parallel processing
• Gradual transition between conscious and
  subconscious processes
• Parallel processing of sensory-motor signals by
  tens of millions of neurons
• Specialized areas of memory responsible for
  various representations
• e.g. shape, color, space, time
• Levels of symbolic representation
• More diffuse than binary logic
• Learning mechanisms as a foundation for
  cognitive science
• When you learn, you change the method of
  information processing in your brain
• Resonance between bottom-up representation and
  top-down understanding
• Prediction and competition of ideas

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Brain Landmarks

• Most terms in neuroscience are Latin names, as it
  was the language of science.
• Medial (midline) view of the brain also called
  mid-sagittal section of the brain is a slice from
  the nose to the back of the head.

• Corpus callosum is a fiber bridge flowing
  between right and left hemispheres, begins behind
  the frontal lobe and loops up and ends in front
  of the cerebellum.

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Brain Landmarks

• Lateral (side) view of left hemisphere is shown
  here.
• Folds in the cortex are important part of
  anatomy.
• Longitudinal fissure runs along the midline
  between right and left hemispheres.

• Lateral sulcus runs forward at a slant along the
  side of the brain and divides the temporal lobe
  from the main cortex.
• Central sulcus divides the rear half (posterior
  half) of the brain from the frontal lobe.

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Brain Landmarks

• Temporal lobe points in the direction of the eye.
• The three major planes of section (cuts) are
• Vertical section (sagittal) from the front of the
  brain to the back.
• Slice through the midline is called mid-sagittal.
• Horizontal slice.
• Coronal section (named for its crown shape).

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Body Landmarks

• The three major planes of section
• Vertical section (sagittal) from the front to the
  back.
• Horizontal (transverse) section.
• Frontal (coronal in the brain) section.

• Other important directions
• Superior (dorsal) and inferior (ventral)
• Medial and lateral
• Anterior (rostral) and posterior (caudal).

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Mind and Brain

• Visual perception viewing natural imagery
• we must understand ways of encoding
• objects and scenes.
• Spatial awareness considering the interaction
• between streams of visual information will let
• us simulate concentration

Memory modeling hippocampal structures allows us
to understand various aspects of episodic memory,
and learning mechanisms show how semantic memory
arises. Working memory explaining the capacity
to simultaneously hold in the mind several
numbers, while performing calculations requires
specific mechanisms in the neural model.
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Mind and Brain

• Reading words the network model in Emergent will
  learn to read and pronounce words and then to
  generalize its knowledge to the pronunciation of
  new words as well as to recreate certain forms of
  dyslexia.

Semantic representations analyzing a text on the
basis of context, the appearance of individual
words, the network will learn the semantics of
many ideas. Decision-making and task execution
A model of the prefrontal cortex will be able to
keep attention on performed tasks in spite of
hindering variables. Development of the
representation of the motor and somatosensory
cortex through learning and controlled
self-organization
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Mind and Brain

• Andreas Vesalius (1514-1564), a Belgian
  physician, published the first known detailed
  anatomy based on dissections of human body.
• He showed that both men and women have the same
  number of ribs.
• Illustrations, like the brain shown here, were
  done by Titian.

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Mind and Brain

• Paintings, like the Rembrandt (The Anatomy Lesson
  of Dr.Tulp), show the excitement generated by
  dissection of human cadavers.
• René Descartes (1596 -1650) a mathematician and
  philosopher is considered as the originator of
  modern mind/body philosophy.

• He said most famously, cogito ergo sum ("I think,
  therefore I am").
• Thinking is thus every activity of a person of
  which he is immediately conscious.
• Descartes' "error" pointed by António R. Damásio
  was the separation of mind and body.

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Mind and Brain

• Charles Darwin (1809 1882) wrote a book
  Expression of emotions in man and animals
  pointing towards biological origins of emotions
  and not just cultural as people thought.
• He also stressed the importance of culture and
  environment, that helps to resolve nature vs
  nurture debate.

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Mind and Brain

• Santiago Ramon y Cajal (18521934) founder of
  brain science studied properties of neurons.

• He observed neurons under microscope and showed
  that they are single cells that end with synapses

• Nerve impulses travel down the axon to synapses
• In 1952 Hodgkin and Huxley constructed action
  potential model for a spiking neuron

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Neurons

• Cajals drawing of a slice of chicken brain
  exposed using Gogli staining method

• A Modern version

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Mind and Brain

• Pierre Paul Broca (1824-1880) discovered the
  region in the brain responsible for speech
  production
• In 1861 he studied a patient with epilepsy who
  lost ability to speak

• On the patients death Broca performed autopsy
  and showed a damage to the posterior part of the
  third frontal convolution in the left hemisphere
  and associated it to speech production
• Much of what we know about brain was first
  discovered by studying various deficits

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Mind and Brain

• Wernickes area (W), in the left upper part of
  the temporal lobe, is an important area for
  receptive language (understanding).
• Carl Wernicke (1848-1905) published his finding
  shortly after Brocas work
• The two areas are connected
• for speech comprehension
• and production.
• Damage (in or near) leads to
• Brocas area (B) Expressive aphasia,
• Wernickes area (W) Receptive aphasia,
• Fibers between B W Disconnection aphasia.

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Mind and Brain

• Left hemisphere is responsible for language
  production and listening while right hemisphere
  is concerned with emotional aspects of language.
• Angelo Mosso (1846-1910), found a way to measure
  blood pressure during demanding mental tasks.
• Mossos work anticipated current measures of
  brain blood flow like fMRI.
• fMRI measures local blood flow changes in the
  brain.
• The fMRI responds to blood flow changes whenever
  some brain regions require more oxygen and
  glucose.

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Mind and Brain

• Nineteen century scientists were very interested
  in consciousness.
• William James (1890) declared psychology as a
  science of conscious mental life.
• Many scientists (Helmholtz, Loeb, Pavlov)
  disagreed they took on a physicalistic view of
  mental life.

• Pavlov experiments with dogs (1900) on classical
  conditioning convinced psychologists that all
  behavior can be derived from simple reflexes.

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Mind and Brain

• In 1970-ies many scientists were dissatisfied
  with behaviorism.
• Different methods of testing conscious and
  unconscious brain events were developed

• Figure compares results of study using visual
  backward masking method based on fMRI to compare
  brain activity for conscious and unconscious
  visual words.

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Conclusion

• Ongoing debates in cognitive neuroscience
• Local vs distributed functions in the brain
• The question of consciousness
• Unconscious inferences in vision
• Capacity limits in the brain
• Short-term and long-term memory separate or
  not?
• The biological basis of emotions
• Nature vs nurture genes vs environment
• Cognitive neuroscience combines psychology,
  neuroscience and biology to answer questions
  about mind and brain.
• Modeling cognitive functions of the brain helps
  to understand psychological phenomena and predict
  behavior.
• It may simplify complex cognitive processing with
  full control of experimental conditions.
• It helps to build working models of embodied
  intelligence

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