Summary
Central Nervous System (CNS)
Peripheral Nervous System
Somatic
Autonomic
The Neuron
Structure
Functions
The Endocrine System
The evolution of the Brain & Comparison Across species
Methods for Brain Research
Brain Structure and it's Functions
The Mysteries of our Two Brains
The Mind-Body Problem
Central Nervous System - the portion of the nervous system consisting of the brain and spinal chord.
Spinal Chord - A collection of neurons and supportive tissue running from the base of the brain down to the centre of the back. video
Reflex: An automatic response to a stimulus, requiring no conscious efforts (that often only requires the spinal chord). video
Peripheral Nervous System - All nerves outside the CNS, includes sensory & motor nerves. video
Somatic Nervous System - The subdivision of the peripheral NS that connects to sensory receptors and to skeletal muscles.
Autonomic Nervous System
- The subdivision of the PNS that
regulates the internal organs and glands (bladder, stomach, heart, blood
vessels)
Sympathetic N S - that mobilizes
bodily resources and increases the output of energy during emotion & stress
(fight or flight - accelerator)
Parasympathetic N S - operates
during relaxed states and conserves energy (digest food - brake)
Biofeedback (Miller, 1969, 1978) - monitoring devices track the bodily processes in question and deliver a signal (light or tone) whenever a person makes the desired response - e.g., blood pressure, heart rate, brain waves, (new tech CBC (muse))
Basic Units of the Nervous System
Neurons: Cells that conduct electrochemical signals, the basic unit of the nervous system. Also called a nerve cell. Arborization.
Cell Assemblies are collections of cells that work together in neural pathways or circuits.
Glial Cells: cells that hold neurons in place, insulate neurons, and provide neurons with nutrients.
Nerve - a bundle of nerve fibres (axons and dendrites) in the peripheral nervous system.
The Structure of the Neuron
Dendrites - a neuron's branches that receive information from other neurones and transmit it toward the cell body.
Cell Body - The part of the neuron that keeps it alive and determines whether or not it will fire.
Axon - a neuron's extending fibre that conducts impulses away from the cell body and transmits them to other neurons.
Myelin sheath - A fatty insulation (oligodendrocytes) that may surround the axon of some neurons, also called white matter. After birth develops in sensory and then motor areas, and in adolescence through to pre-frontal cortex.
Synapse
- place where transmission of nerve impulses go from one neuron to the
next. alt fig
- Includes the axon terminal, the synaptic cleft, and receptor sites in
membrane of the next cell.
Action potential -Electrical impulses or current travelling down nerve cell. Two types of action. video, AP2
unmyelinated smooth flow of current or potential
myelinated jumping skipping flow of potential hopping down nodes fig
Synaptic end bulb - synaptic vesicles - little sacs that release neurotransmitters. video
Neurotransmitter
- a chemical substance that is released by a transmitting neuron at the
synapses and that alters the activity of a receiving neuron.eg.,
acetylcholine - transmits between
nerves and muscles and
in Pons (REMSleep); also memory & learning
dopamine - important in "reward" system, important in
schizophrenia & Parkinson's syndrome;
also learning, movement and emotion
serotonin - involved in sleep, dreaming, mood,
arousal & emotions (SS)
GABA - involved in inhibition and regulation of anxiety
Receptor sites - lock and key only certain ones fit.
excitatory - increase potential of receptor firing
inhibitory - decrease probability of receptor firing
Neuromodulators - chemical messengers in the NS that increase or decrease the action of
specific neurotransmitters. Drugs will affect action of
neurotransmitters: release, re-uptake,
block, ...
E.g., Cocaine blocks re-uptake of
dopamine leading to longer effects then lowered levels
Endorphins - chemical substances in the nervous system that are similar in structure and action to opiates; they are involved in pain reduction, pleasure, and memory and are AKA endogenous opioid peptides.
Hormones - chemical substances secreted by glands that affect the functioning of other distal organs.
Endocrine Glands - Internal Organs that produce hormones and release them into the bloodstream.
-e.g., Melatonin - A hormone, secreted by the pineal gland that is involved in the regulation of daily biological rhythms -sleep cycles & jet lag)
-e.g., Sexual Hormones (testosterone, estrogen)
Evolution of the brain & Comparison across species
The Older parts of the
brain are the "lower" ones, evolutionarily speaking. Paul McLean (1973)
suggested that we have a "triune" brain. This three part brain is comprised
of:
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Elsewhere comparisons have been made
between language areas
across species and
other areas.
Invasive Techniques:
Lesion method
(extirpation) - involves the removal or cutting of
parts of the brain to see what effects it has on psychological function.
Electrode method - inserting an electrode (small needle or wiring) into parts of the brain to either record or stimulate brain activity.
This is used to probe the brain prior to surgery, as pioneered by Dr. Wilder Penfield.
-microelectrodes can be inserted into
single cells to measure their
activity
Non-invasive
techniques
Surface electrodes - disks taped to the head to record activity in that part
of the brain, usually measuring 'brainwaves' or cyclical patterns of
neuro-electrical activity of millions of neurons.
EEG electroencephalogram - a device for recording neural activity detected by electrodes. Contemporary EEG helmet
Evoked potentials - patterns of brain activity produced in response to specific events.
PET scan (positron-emission tomography) - a method for analysing biochemical activity in the brain, using injections of a glucose-like substance containing a radioactive element.
People with special abilities may not have different overall structures, but rather fewer circuits to do the task, or more efficient operations.
MRI (magnetic resonance imaging) - a method for studying body and brain tissue, using magnetic fields and special radio receivers.
- a computer analyses the signals
and blood flow and activity in 'fast' or functional MRI (f-MRI) MRI Basics
Structures of the Brain and Their Functions
Localisation of Function- specialization of particular brain structures or areas for particular functions. 3D brain site
Pons - rostral (anterior) to medulla, is involved in sleeping, waking, and dreaming, and relays information from the cerebrum to cerebellum.
Reticular Activating System (RAS) - a dense network of neurons found in the core of the brainstem; it arouses the cortex and screens incoming information.
Midbrain
- rostral
(anterior) to pons, involved in control of eye movement
relays to auditory and
motor movement
Structures: Tectum (superior colliculus, inferior colliculus, substantia nigra)
Cerebellum - 'lesser brain' - a structure that regulates movement and balance, and timing that is involved in the learning of simple kinds of responses.
Hypothalamus - A brain structure involved in emotions and drives vital to survival (eg., fear, hunger, thirst, & reproduction) it regulates the ANS through pituitary secretions.
Pituitary Gland - a small endocrine gland at the base of the brain which releases many hormones and regulates other endocrine glands
Limbic System - A group of brain areas involved in emotional reactions and motivated behaviour.
-emotions and 'pleasure centre' (septal area) of rat brains as seen in repeated bar pressing in a study by Olds & Milner, 1954)
Amygdala - a
brain structure involved in the arousal and regulation of emotion and the
initial emotional response to sensory information (Appraisal) connects with Olfaction (smell), Prefrontal & Temporal Cortex (planning), Hypothalamus & Brain Stem).
-evaluating sensory information; anxiety and depression.Capgras'
Syndrome
Hippocampus - a brain structure involved in the storage of new information in memory - Gateway to memory.
"HM" - man with no memory for new events,
although he could learn new tasks or skills (e.g., learned to play tennis,
problem solve) but didn't have recall for these
events.
Eric Kandel's work on
memory
Corpus Callosum - the bundle of nerve fibres connecting the two hemispheres
Cerebral Cortex - several thin layers of cells covering the cerebrum, "grey-matter" cell bodies of the cortex "white-matter" is myelinated (covered) axons elsewhere in the brain
Occipital Lobes - lower back part of the brain AKA visual cortex
Parietal Lobes - top and side walls - somatosensory areas with more sensory function have larger areas (i.e., face and hands)
Ramachandran's Peggy E1-4 E1-5
Temporal Lobes - sides of brain (temples) involved in memory, perception, emotion and language, including the auditory cortex.
Experience God Prosopagnosia -Facial Recognition disability
Frontal Lobes - Front - forehead - contain motor cortex for voluntary movement, and ability to make plans, think creatively and take initiative.
Prefrontal
Cortex - most anterior parts of frontal cortex
mice & rats -3.5% in cats, 7% in dogs, 17% in chimps, 29% in humans. > personality
Case of -Phineas Gage - tamping rod through pf cortex - "was able to speak, think, & remember but he
changed his personality from 'mild-mannered', friendly, efficient work into a
foul-mouthed, ill-tempered, undependable lout who could not hold a steady job or
a plan." This is an area that controls other areas (i.e. limbic system) and implies "free-will"
Our Two Cortical
Hemispheres
Split brain:
Two
minds in one head
1953 Myers & Sperry - severed the corpus callosum in cats. Blindfolded one eye - learn to push bar to get treat. Changed eyes and it acted as though it had learned nothing.
Spilt-Brain Surgery
Most people have language
in left brain
- Temporal Wernicke's
area comprehension and meaning
- Frontal
Broca's area for production
Presented "split images" - Faces cut in
half to each visual field - brief exposure
-say what you saw (left
brain) - Right side image>>verbal -right visual field
-point with left hand (right brain) - Left side image
Split brain - Chicken claw to
left hemisphere & snow to right then have point to related pictures chicken
& shovel each pointed to each object & explained claw went with chicken
and shovel was for cleaning the coup (no verbal awareness of the snow).
Gazzaniga
The special abilites of the Right & Left Brains
Language is typically in the left hemisphere for nearly all right handers and most left handers.
Left side is also more active for some logical tasks (i.e, math problems & technical understanding)
Right side
mental skill vastly
inferior to cog level of a chimpanzee and that left side tries to explain
actions or emotions from non-verbal side (Gazzaniga, 1983)
Right side - superior in problem requiring spatial - visual facial recognition, music, art, non-verbal sounds (dog bark) & some language ability including metaphors (Sperry, 1982).
Rational analytic vs. intuitive, holistic
Jill Bolte Taylor's report on her stroke and right hemisphere
Lateralisation -challenges: Lefthanders in a Righthanded world.
The problem of localization: Where are our thoughts and memories stored?
Lashley (1950) searching for the "n-gram" maze learning in rats - systematically extirpated various areas and amounts of rat's brain tissue.
The Mind- Body problem revisited
Plasticity: Recent cases of
hemispherectomies
suggests that the right can pick up a great deal of what the
left had done for maturing children after age six or seven.
The brain that changed itself (Doidge, 2010) thinking and other "brain activity" changes the brain. Brain exercises to change your brain.
Cochlear implants and tongue stimulators that enable blind people to see have build on these principles. (More later during sensation C2, ... )
Are there 'his' and 'her'
brains?
slight anatomical differences - women less
lateralized than men & huge variation within genders more so than
between them!!
See Doreen Kimura's work on gender brains and cognition
Gender &, Hormones The
varieties of gender & Sexuality Gender Bread Person