lecture01.ppt

PH19510 - Chaos, Communication and “ Consciousness” Dr Tony Cook a t c @ a b e r . a c . u k Lecture #1 “ What is Consciousness and the Human Brain?” 8 th Oct 2007 09:00-10:00 in Room 320 Web Site: http://users.aber.ac.uk/dpl/ph19510/ph19510.htm

The Previous Lecture
Pre-electronic Communication
Pictographs
Development of the alphabet
Number systems
Printing
Transfer of Information
Navigation
Signalling

Contents of Consciousness Lectures
What do we mean by consciousness? - today
The human brain and its geography - today
The Brain vs. the computer - Thursday
Artificial Intelligence - Thursday
Turing test - Thursday
Robotic systems – another day

Consciousness
Consciousness has traditionally been the preserve of Philosophy, Theology, Psychology and Literature by attempting to answer the question “Why?”
Now the challenge is coming from Physics, Mathematics, Computer Science and Neuroscience...... by attempting to answer the question “How?”
Interesting Books to read (but only if you have time).....
Roger Penrose The Emperor’s New Mind (Vintage, 1990) ISBN 0 09 977170 5
Francis Crick The Astonishing Hypothesis (Touchstone Books, 1995) ISBN 0 671 71295 0
Stephen Jay Gould Ever Since Darwin (Penguin Books, 1991)
Peter Atkins Galileo’s Finger (Oxford, 2003) ISBN 0 19 860941 8

Dictionary Definition of Consciousness “ Consciousness ” : the state of being conscious; awareness of one's own existence, sensations, thoughts, surroundings “ Unconscious ” : not conscious, effects behaviour, emotions “ Aware”: knowledge, informed, being awake “ Knowledge” : awareness of familiarity gain by experience “ Perceive” : identify by means of the senses, recognize “ Mind” : seat of consciousness, intellect, memory “ Intellect” : power of the mind where one knows and understands “ Memory” : ability of retaining/recalling facts, events, impressions “ Reason”: intellectual process at which conclusions are drawn “ Behaviour”: the way one conducts oneself, manners

Facts about the human brain
The brain is supported in the cerebrospinal fluid (CSF) and only weighs 50g protecting it from shocks
Brain 23% mass of fetus at birth
The brain grows at a similar rate as a fetus for 12 months after birth.
Weighs about 1.3kg and is 2% of body mass
Elephant brain: 6kg and a cats: 30g
The human brain is approximately 75% water
A brain consists of about 100 billion neurons
Largest brain in the world belongs to the blue whale and weighs 6kg
20% to 60% of body energy is consumed by the brain

Brain size and evolution For given species, brain size increases with body weight through evolutionary sequence Pithecanthropus Alalus - predicted by Ernst Haekel Java Man – discovered by Du Bois

How do we map the brain?
Brain accidents, surgery, animal and human experiments
Electroencephalograms (EEGs); (brainwaves) Measures the global electric activity of the brain
Positron Emission Tomography (PET); Shows up abnormal tissue over the entire body. Shows up mental activity
Computerized Axial Tomography (CAT); Generates a 3D image of the whole body by X-ray absorption, good for dense material
Magnetic Resonance Imaging (MRI); Generates 3D images of the whole body using radio waves, good for soft material (harmless)

Generated data. EEGs PET CAT MRI

Electroencephalograms (EEGs)
Neural activity results in changing currents which induce changing voltages on the scalp.
Detected by attaching electrical contacts and measuring the amplified signals over time.
EEGs have been around for over 60 years and register mostly global electrical activity
PET

Electroencephalograms (EEGs)
Can see sleep and waking states
Chaotic attractor patterns can be seen, indicating specific states e.g. epilepsy.
Can isolate specific states by removing average brain activity
Parietal and occipital lobes are very active when the eyes are closed.
During sleep the frontal lobes can also be active.
The whole brain displays broadly similar activity during rapid eye movement (REM) sleep compared to being awake.
PET

Positron Emission Tomography (PET).
A short-lived radioactive form of glucose is ingested – it emits positrons.
Neurons burn glucose when firing, releasing electrons.
These electrons are annihilated by the positrons, releasing gamma rays which can be detected by an annular array of detectors.
Images are built up of gamma ray release
Can detect thought processes
Can detect diseased areas
Normal (left), seizure (right)
PET

Sleeping and Waking in PET Scans
Parietal and occipital lobes are extremely active when the eyes are closed.
During sleep the frontal lobes can also be active.
The whole brain displays broadly similar activity during rapid eye movement (REM) sleep compared to being awake.
PET

Examples of Localised Brain Activity – PET Scans
Language Music
PET temporal lobe and Wernicke’s Area visual lobe and angular gyrus Broca’s area and frontal lobe listening to music right hemisphere resting

Visualization Tasks in PET Scans
Perceiving visual objects and occurrences follow a law of functional specialisation, whereby different attributes such as form, colour and motion are processed geographically in different parts of the visual cortex.
PET In particular V1 and V2 areas close to the back of the occipital lobe deal with the initial signals from the brain and are generally always active when the eyes are open. Motion activates area V5 which is more remote on the outside of the occipital lobes . Colour is dealt with in area V4 , further in towards the corpus callosum

Computerised Axial Tomography (CAT)
Uses an external source of radiation, X-rays, which are absorbed differently by tissue, bone and blood.
The X-ray source rotates around the patient and the changing absorption is detected diametrically opposite as a function of angle and longitudinal distance.
3D images are reconstructed by computer tomography techniques and provide static maps of the brain.
PET

Magnetic Resonance Imaging (MRI)
Records the resonance of nuclear spin levels split by a large magnetic field which surrounds the patient.
The resonances occurs at radio frequencies, different values of which will excite specific nuclei - protons in water for instance
PET
Radio waves are used to excite the nuclear levels which then relax emitting radio frequency radiation from a given nucleus, which is then detected.
The location of specific NMR resonances can be recorded in 3D as a function of time.

Map of Brain using MRI
Emotions Schizophrenia
PET hypothalmus – keeps body’s internal environment in steady state – regulating thirst, hunger and body temperature Schizoid – fluid enlarged brain region normal

Mapping the Brain and Imaging Activity
In all cases (apart from EEG) 2D “slices” can be made from the 3 dimensional images non-invasively and at any angle!
CAT scans are slow but comparatively cheap and are generally used to locate brain damage or brain disorder.
PET and MRI can be used as a function of time and are more versatile but expensive.
Moreover (like EEG’s) background brain activity can be subtracted to pinpoint those parts of the brain responding to specific stimuli

Geography of the human brain Cerebrum Cerebellum

Cerebellum
Used to integrate sensor information and motor output and is used for reflex action
Using constant joint feedback via the spinocerebellar it can control fine-tune motor movements
Lesions (abnormal tissue) within the cerebellum are not so debilitating
Contains nearly 50% of all neurons in the brain only 10% of the brain volume.
Nearly 200 million input fibres (optical nerve has only 1 million)
It has two large hemispheres and is divided into ten smaller lobes.
Energy consumption 20%

Cerebrum
Largest in all species
Generally regarded as the seat of consciousness
Determines Intelligence
Personality
Interpretation of Sensory Impulses
Motor Function
Planning and Organization
Touch Sensation
Divided into four main areas: (1) frontal lobe (motor action), (2) parietal lobe (sensation), (3) temporal lobe (smell) and (4) occipital lobe (vision)
There is also a left-right swap (see next slide!)

Divisions and Functions of the Cerebrum
The Cerebrum is divided into two hemispheres - the left and the right viewed from the top - separated by the corpus callosum . The left cerebral hemisphere is largely concerned with sense detection and physical activation from the right whilst the right cerebral hemisphere mainly deals with left-handed operations.

The Frontal Lobe
Contains the motor cortex for voluntary body movement
Plays a part in impulse control, judgment, language, memory, motor function, problem solving, sexual behaviour, socialization and spontaneity
Assist in planning, coordinating, controlling and executing behaviour
Damage can cause:
Loss of fine movements and loss of strength (arms, hands, fingers)
Impaired interpretation of environment feedback and spatial orientation
Often personality and social behaviour disorders
Central fissure

Frontal Lobe Layout Reasoning Problem Solving Emotions Personality

The Parietal Lobe
Two functional regions;
Integrates sensory information from various parts of the body
Generates a spatial coordinate system of the environment for the manipulation of objects
Sections are involved in visual spatial processing
Least known about this lobe
Damage:
left lobe:- left right confusion, difficulty with writing and maths
Right lobe:- neglect parts of the body, difficulty making things

Parietal Lobe Layout Spatial Sense

The Occipital Lobe
With the exception of smell, almost all sensory information is handled on the opposite side of the brain.
Centre of visual processing system
Visual cortex receives information from the outside half of the retina the same side and the inside half of the retina on the opposite side
Damage:
visual defects
visual hallucinations
Illusions
object distortions

Occipital Lobe layout Information from the eyes Line and angles Distance, motion and shape Object recognition

The Temporal Lobe
Primary role is the organisation of sensory input
Associated with memory skills
Left lobe; verbal material
Right lobe; non verbal material (music, drawings)
Damage can cause:
left lobe recognition of words impaired memory for verbal material
right lobe inhibits talking, impaired memory for non verbal material
Paranoia, aggressive rages
Lateral fissure

Temporal Lobe Layout Speech Language Hearing Memory

Emotions, Memories and Alertness All the somatosensory information of the cerebrum is pre-processed elsewhere. All-embracing mental states that constitute the emotions, memory acquisition or alertness are not controlled by the cerebrum . The origins of these “higher level functions” appear to reside, or at least derive from, areas in the middle brain . This is situated on the stem of the spinal cord, adjacent to the cerebellum and below the cerebrum .

Emotions, Memories and Alertness Emotions, Memories and Alertness The thalmus gets all the information from sensory organs and pre-processes it en route to the cerebrum . The hypothalmus is the seat of the emotions , mediating the mental and physical manifestations of fear, rage, pleasure, hunger, despair etc. Signals travel continually between here and the cerebrum . thalmus limbic Long-term memories are established, at least primarily, by the limbic system or hippocampus and stored in the cerebrum . Short-term memories can be “kept in mind” by the cerebrum but, once the attention span has lapsed, they can only be retained in conjunction with the hippocampus.

Emotions, Memories and Alertness Emotions, Memories and Alertness limbic
The reticular formation at the top of the pons is responsible for alertness in the brain as a whole or in different parts in particular. Its function crudely seems to relate to switching the cerebrum on and off. It activates awareness . The reticular formation is comparatively inactive during deep sleep or coma and if it is damaged unconsciousness results. The reticular formation is therefore generally regarded as the “seat of consciousness” . It appears that the state of consciousness is a focus of processes linking the reticular formation with the various parts of the cerebrum .

Broca’s Area
Main region for language processing and speech production
Two parts;
Pars triangularis
Pars opercularis.
Damage:
unable to form complex grammatical sentences
e.g. "Yes... ah... Monday... er... Dad and Peter H... (his own name), and Dad.... er... hospital... and ah... Wednesday... Wednesday, nine o'clock... and oh... Thursday... ten o'clock, ah doctors... two... an‘ doctors... and er... teeth... yah
Central fissure Lateral fissure

Angular Gyrus
Related to language and cognition (reading)
Located at the centre of specialised functions
Outer body experience
Damage
Unable to connect visual stimuli to language
e.g.
Central fissure Lateral fissure Booba and Kiki

Wernicke’s area
Located in the left hemisphere
Comprehension of spoken words
Damage:
can hear language but cannot understand it
Produce grammatically correct sentences but with no meaning
Central fissure Lateral fissure

Information Transfer from Feelings into Action The mechanics of reading aloud are sequenced ...... Starting from word visualisation in the occiptal lobe (primary), word conversion occurs in the angular gyrus (secondary) with word comprehension being reached in Wernicke’s area (tertiary). This word information is then transferred from the parietal lobe along the arcuate This mechanistic view of the operation of the brain has fuelled the debate that the brain functions as a Turing machine and that our mental faculties might eventually be simulated by algorithmic computers fasciculus to Broca’s area (tertiary) and on through the frontal lobe to actuate the tongue, larynx and diaphragm from close to the central fissure . .

Brain Summary
The main areas of the brain, Cerebrum, Cerebellum, fissure’s etc
Various lobes and their function
Where they are located in the brain
Thursday’s lecture will compare and contrast the brain with a computer and introduce Artificial Intelligence (A.I.)
Closing thought – “always look after/protect your brain, it is the most important part of you - it is you!”

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by artintelligence on Dec 31, 2010

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