Introduction to Cognitive Neuroscience

1
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
2

• 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

2
3
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.

4
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?

http//www.harunyahya.com/image/darwinizm_kanli_id
eolojisi_fasizm
5
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?

6
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.
7
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
8
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

9
Inside 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
10
Levels of description
Summary (Churchland, Sejnowski 1988)
Sensing outside and inside the body
11
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.

11
12
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.

12
13
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

13
14
Neurocognitive Models

• Computational cognitive neuroscience detailed
  models of cognitive functions and neurons.

15
Model of self-organization

• Topographical representations in numerous areas
  of the brainvisual 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.
16
Dynamic model

• Strong feedback, neurodynamics.
• Hopfield model associative memory, learning
  based on Hebbs law.

Vector of input potentials V(0)Vini , i.e. input
output. Hopfields network reaches stationary
states, or the answers of the network to the
posed question Vini (autoassociation).
17
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 continuous phenomena (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

18
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 specify in a
  model.
• Even if models work, that doesnt mean that we
  understand the mechanisms.
• Many 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 is very
  important.
• Knowledge acquired from models should
  accumulate.

19
Cognitive motivation

• Although the thinking process seems to be
  sequential information processing, more detailed
  models predict parallel processing
• Transition between conscious and subconscious
  processes
• Parallel processing of sensory-motor signals by
  millions of neurons
• Specialized areas of memory responsible for
  various representations
• e.g. shape, color, space, time
• Levels of symbolic representation
• More diffuse and fuzzy 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

20
Brain Landmarks

• Most terms in neuroscience are Latin names.
• Medial (midline) view of the brain also called
  mid-sagittal 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.

20
21
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.

21
22
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).

23
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).

24
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.
25
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.

25
26
Mind and Brain

• Paintings, like the Rembrandt (The Anatomy Lesson
  of Dr.Tulp), show the excitement generated by
  dissection of human body.
• 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.

26
27
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.

27
28
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

28
29
Neurons

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

• A Modern version

30
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

30
31
Mind and Brain

• Wernickes area (W), in the left upper part of
  the temporal lobe is responsible 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.

32
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 shows whenever some brain regions
  require more oxygen and glucose.

32
33
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.

33
34
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.

34
35
Conclusion

• Debates in cognitive neuroscience
• Local vs distributed functions in 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

http//psychandneuro.duke.edu
35