Brain and Behaviour Flashcards
What is cognition? Give 4 examples
Higher mental processes e.g., thinking, speaking, acting, planning
What is behavioural neuroscience?
Scientific study of how brain activity influences behaviour
What is cognitive neuroscience?
Study of neural basis of behaviour
What can understanding the neural basis of a mental process help distinguish between?
Different theories relating to how that process is performed
What are mental representations?
The sense in which properties of the outside world (e.g., colours, objects) are copied by cognition
What are neural representations?
The way in which properties of the outside world manifest themselves in the neural signal (e.g., different spiking rates for different stimuli)
What word is associated with mental representations?
Simulation
What word is associated with neural representations?
Implementation
Where did Aristotle and Plato think mental experiences came from? (Historical perspectives)
Aristotle - heart
Plato - mind
What is the mind-body problem? (Historical perspectives)
How can a physical substance (brain/body) give rise to mental experiences?
Who had the theory of dualism and what was the basic idea? (Historical perspectives)
Descartes
Mind (eternal) and body (mortal) are separate substances
What did Descartes believe about the soul (Dualism - Historical perspectives)
It controls the movement of muscles through influence on the pineal body
How did Descartes believe our muscles moved? (Dualism - Historical perspectives)
The eye send visual info to the brain
The soul examines this info and decided to act
The soul tilts the pineal body
This diverts pressurised fluid through nerves to appropriate muscles
Who proved Descartes wrong and how? (Historical perspectives)
Galvani
electrical stimulation of decapitated frog nerves’ caused contraction of attached muscle
Muscles contracting was its own characteristic
Brain didn’t inflate muscles with directed pressurised air
What is dual aspect theory?
Mind and body are 2 levels of explanation of the same thing
e.g. like photons with wave-particle duality
What is reductionism?
Mind will eventually be explained solely in terms of physical/biological theory
True or false?
Dual-aspect theory and reductionism are issues still relevant to modern cognitive neuroscience
True
What do psychologists often deal in terms of?
Generalisation e.g., behaviours as general laws
What do physiologists often deal in terms of?
Reduction e.g., complex behaviour explained in simpler terms
What is the modern history of behavioural neuroscience?
combined experimental methods of psychology and physiology and applied them to issues that concern all psychologists
e.g., recent interest in studying physiology of pathological conditions such as addiction and MH disorders
What surgery have split brain patients had and why?
Splitting of corpus callosum to cure severe epilepsy
What is the corpus callosum?
A bundle of nerve fibres connecting the left and right brain hemispheres
Who studied split brain patients?
Sperry and Gazzinga
What did Sperry and Gazzinga find about split brain patients?
Left hemisphere = language (and right side motor control)
Right hemisphere = motor control of left side
What is used to insure that stimuli are only presented to one hemisphere in split brain patients?
Tachistoscope presentation
How quickly do stimuli need to be presented for in a Tachistoscope presentation and why?
150ms or less
Eye movements cause loss of lateralisation and 150ms is faster than the eye can move from central fixation to stimuli
What were the results of Sperry and Gazzinga’s experiments on Split brain patients?
object presented to RVF, ppt verbally names object
object presented to LVF, ppt “sees nothing” but can use left hand to pick out correct object
What side of brain is smelling processed on?
Same side hemisphere
What is smelling like in split brain patients?
Smelling on left is process by LH and can name smell
Smelling on right is processed by RH and can choose corresponding scent with left hand
What does lateral mean?
Towards side
What does medial mean?
Towards middle
What does dorsal mean?
Top
What does ventral mean?
bottom
What does rostral (anterior) mean?
Front
What does caudal (posterior) mean?
Back
What is the neuraxis?
Imaginary line from head to toe
What does ipsilateral mean?
same side
What does contralateral mean?
opposite side
What are the 3 ways of slicing the brain?
Transverse section - right angle to neuraxis
Sagittal section - parallel to neuraxis and perpendicular to ground
Horizontal section - parallel to ground
What is the CNS made up of?
Brain and spinal cord
What is the peripheral NS made up of?
Cranial and spinal nerves
What is the texture of the brain?
Soft and jelly like
How much does the brain weigh?
Approximately 1400g
How much body weight does the brain account for?
2%
What is the brain protected by?
Skull and CSF
True or false?
Different areas of the brain support different functions?
True
How much blood and oxygen does the brain use?
20% of blood supply
15-20% of oxygen
How long are the blood vessels in the brain?
400 miles
What is the Foramen Magnum? Where is it located?
Large hole for passage of spinal cord in the skull
What are the 3 Meninges
Dura Mater - tough, flexible, outermost meninx
Arachnoid - middle layer, like cellophane draped around brain, doesn’t dip into valleys of brain contour
Pia Mater - last layer, adheres to surface of brain
What is the subarachnoid space?
The space between the arachnoid and pia meninges
It is filled with CSF
What are ventricles?
A set of hollow chambers within the brain filled with CSF
What are the 4 ventricles?
Lateral ventricles
Third ventricles
Cerebral aqueduct
Fourth ventricle
What is cerebrospinal fluid (CSF) like?
similar to blood plasma composition
How is CSF formed?
By the choroid plexus
What is the purpose of CSF
To form a watery cushion to protect the brain
Where is CSF circulated?
Arachnoid space
ventricles
central canal of spinal cord
What is the total volume of CSF?
How many times does it turn over a day?
125-150 ml
3-4 times a day
Where is CSF secreted and what does it do constantly?
Secreted by brain
Constantly made, circulated and reabsorbed into bloodstream
What is Hydrocephalus in infants? What happens?
Happens when CSF is not reabsorbed
doesn’t circulate around the brain or leave properly instead it sits in ventricles
leads to expansion of the head
Which ventricle(s) are in the forebrain?
Lateral and Third
Which ventricle(s) are in the midbrain?
Central aqueduct
Which ventricle(s) are in the hindbrain?
Fourth
What are the 3 major divisions of the brain?
Forebrain
Midbrain
Hindbrain
Which is the largest major division of the brain?
The forebrain
What are the 2 subdivisions of the forebrain?
Telencephalon and Diencephalon
What are the principle structure of telencephalon?
Cerebral cortex
Basal ganglia
Limbic system
What does the cerebral cortex look like?
The outermost layer of the brain
Thin wrinkled layer of tissue consisting of 2 hemispheres that are connected via the corpus callosum
Crumpled up to fit into skull (area = 2500cm^2)
What are the 5 key structures of the cerebral cortex?
- sulcus = grove
- fissure = deep sulci
- gyrus = bulge
- grey matter = made up of cell bodies of neurons
- white matter = made up of axons and dendrites
What are the 4 lobes of the cerebral cortex?
Frontal
Parietal
Occipital (FPOT)
Temporal
What is the function of the frontal lobe?
primary motor cortex
controls different areas of body
What is the function of the parietal lobe?
primary somatosensory cortex
receives external information about the senses
What is the function of the temporal lobe?
primary auditory cortex
processes auditory information
what is the function of the occipital lobe?
primary visual cortex
processes visual information
What divides the 4 lobes?
Fissures
Which fissure divides the frontal and temporal lobes?
Sylvian fissure
Which fissure divides the frontal and parietal lobes?
Central fissure
Which fissure divides the parietal and occipital lobes?
occipital fissure
Which fissure divides the temporal and occipital lobes?
Extra occipital fissure
What type of organisation does the motor cortex have? What does this mean?
Somatotopic organisation = body parts that are used more (e.g., hands, tongue) have more dedicated areas of motor cortex than those used less frequently
What are Brodmann areas?
different regions of the cerebral cortex that are defined based on their structure and organisation of cells
What is cytoarchitectonics?
the study of the cellular composition of the central nervous system’s tissues under the microscope
How many Brodmann areas are there?
47
Why are Brodmann areas useful?
They have been closely correlated to different cortical functions
e.g., areas 1, 2, and 3 = primary somatosensory cortex
e.g., area 17 = primary visual cortex
This allows people to describe exact parts of the brain for things like damage
What is the Limbic system?
A set of structure involved in learning, memory and emotion
What 5 structures are a part of the limbic system?
Limbic cortex
Hippocampus - memory and memory recognition
Amygdala - processing emotions (especially negative emotions)
Fornix
Mammillary bodies (part of hypothalamus)
What is the Basal Ganglia?
A set of structures involved in movement
What are the 3 structures of the Basal Ganglia?
Caudate nucleus
Putamen
Globus Pallidus
What are the principle structures of Diencephalon?
Thalamus
Hypothalamus
What is nuclei?
Group of neurons of similar shape
What is the Thalamus?
Main sensory relay for all senses (except smell) and the cortex
Is subdivided into different parts for processing information from the different senses
What is the hypothalamus?
- set of nuclei involved in regulating the autonomic NS and controlling the pituitary gland
- much of endocrine system is controlled by hormones produced in hypothalamus
- concerned with body and regulation e.g., fighting, feeing, fleeing and mating
What is the subdivision of the midbrain?
Mesencephalon
What are the principle structures of mesencephalon?
Tectum
Tegmentum
What are the 2 structure of the Tectum
superior colliculi
inferior colliculi
What is the superior colliculi?
the subcortical sensory pathway involved in fast eye movements (vision)
What is the inferior colliculi?
Part of the auditory pathway
What is the role of the Tegmentum?
Role in motor movement
What are the 3 structures of the Tegmentum?
Reticular formation
red nucleus
substantia nigra
What is the subdivisions of the the hindbrain?
Metencephalon and myelencephalon
What are the principle structures of metencephalon?
Cerebellum
Pons
What is the cerebellum?
mini brain
involved in motor coordination and smooth execution of movement
What is Pons?
Part of the reticular formation
Involved in sleep and arousal
It is the link between the cerebellum and cerebrum
What is the principle structure of myelencephalon?
Medulla oblongata
What is the medulla oblongata function?
Involved in basic life functions
e.g., breathing, swallowing, vomiting, coughing, sneezing, heart rate, wake-sleep cycles
What is the structure of the spinal cord?
Grey matter in middle, surrounded by white matter
Butterfly like structure with wings facing towards body
What is the function of the spinal cord?
Communicates with sense organs and muscles below head level
What are the primary components of the spinal cord?
Dorsal roots and ventral roots
What are dorsal roots?
Carry sensory information to CNS = afferent
What are ventral roots?
Carry motor information to muscles and glands away from CNS = efferent
What is the peripheral NS?
Located outside skull and spine
Bring information into CNS and carries signals out of CNS
contains somatic NS and autonomic NS
What is the somatic NS?
Control movement of skeletal muscles
transmits somatosensory information to CNS
What is somatic NS made of?
cranial nerves and spinal nerves
What are afferent nerves?
Carry information towards CNS
What are Efferent nerves?
Carry motor information to muscles and glands and away from CNS
How many cranial nerves are there?
12
What are cranial nerves?
Attached to ventral surface of brain
control sensory and motor functions of head and neck
some are efferent and some are afferent
What are spinal nerves?
Peripheral nerves attached to spinal cord
Are efferent and afferent and travel to muscles and sensory receptors
What is the autonomic NS?
Controls body’s vegetative functions e.g., heart
regulation of smooth muscles, cardiac muscles and glands
all nerves are efferent
What is the autonomic NS made up of?
Sympathetic NS and Parasympathetic NS
These divisions have opposite effects
What is the sympathetic NS?
Fight or flight
arousal and preparing body for expenditure of energy
e.g., increased: heart rate, breathing and gland secretion
What is the parasympathetic NS?
Rest and restore
relaxing body
opposite effect of sympathetic NS
What type of cell makes up the NS?
The neuron
What does the neuron do?
Support cognitive functioning
Transmits and processes information
What are the key structure of a neuron
Dendrites Axons Soma (cell body) Myelin sheath Terminal buttons
What are the 3 types of function of neurons
Sensory - detect changes in external and internal environment
Motor - control muscle contraction and gland secretion
Interneurons - lie within CNS and are involved in cognition
What are the 2 types of interneurons?
Local and projection
What are the different types of structures of neurons?
Multipolar neuron - 1 axon, many dendrites attached to soma
Bipolar neuron - 1 axon, 1 dendrite attached to soma
Unipolar neuron - 1 axon attached to soma, axon divides with one branch receiving sensory information and another sending sensory information to CNS
How did early anatomists discover neurons
Golgi staining technique
Cajal used this to find pyramidal cells
How many types of multipolar cells are there? What are they?
3
Motor neuron, pyramid cell, Purkinje cell
What are Glial cells? Where are they found?
Supporting cells that glue the NS together
Found in CNS
What are the 4 types of glial cells?
Oligodendrocytes
Astrocytes
Microglia (modified immune cells)
Ependymal
What do oligodendrocytes form?
Myelin sheath
What do astrocytes form, help form, secrete and take up?
form support for CNS
help form blood-brain barrier
secrete neurotropic factors
take up K+ neurotransmitters
What does microglia act as?
Scavengers
What does ependymal cells create? What are they?
Create barriers between compartments
are sources of neural stem cells
What does the microglia do?
Control immune response of the brain
What do oligodendrocytes do?
support axons and produce myelin sheath which provides insulation and is made of lipids
What are the nodes of Ranvier?
Bare part of axon
How many Schwann cells wrap round axon in CNS and PNS?
CNS = many PNS = one
What do astrocytes do?
“star cells”
provide physical support to neurons
provide nourishment by taking glucose from bloodstream and breaking it down for neurons
clean up debris and form scar tissue when neurons die
control chemical composition of fluid surrounding neurons
What is the blood-brain barrier?
A semipermeable barrier between CNS and circulatory system which helps to regulate flow of nutrient rich fluid into the brain
Are all areas of blood-brain barrier equally permeable? Give an example
No
Area Postrema - region of medulla where blood-brain barrier is weak. Allows toxins in the blood to stimulate this area - initiates vomiting so poison is expelled from body
Give an example of a useful behaviour that only involves neurons, How does it work?
Reflexes e.g., withdrawal reflex
sensory –> interneuron –> motor
happens in Spinal cord
What is a membrane potential?
electrical charge across cell membrane
the difference in electrical potential in and out of cell
stored up source of electrical energy
What is resting potential?
Membrane potential of neuron when it isn’t being altered by excitatory/inhibitory postsynaptic potentials
about 70mV
What is depolarisation?
Reduction of the negative charge (toward 0) of membrane potential when we stimulate neuron
What is action potential?
brief electrical impulse that provides the basis for conduction of information along an axon
results from movement of ions through membrane
What is the threshold of excitation?
The value of the membrane potential that must be reached to produce an action potential
What is hyperpolarisation?
increase in the membrane potential of a cell
What are the 2 forces that membrane potentials go through to remain balanced?
Diffusion and electrostatic pressure
What is intercellular and extracellular fluids?
Intercellular = fluid within cells Extracellular = fluids outside cells
Draw the process on diffusion and electrostatic pressure across a cell membrane
Involve Na+, K+, Cl- and A- ions
drawing on Wk 3 Lecture 3 notes
How can Na+ be found outside of cell when both diffusion and electrostatic pressure push it inside?
Sodium-potassium pump
a protein that is an active transporter - pumps 3 sodium ions out and 2 potassium ions in
What type of ion channel allows ions to move through membrane? How does it work?
Voltage dependent (gated) ion channels - a protein that allows flow of specific ions, opens and closes depending on charge that arrives to it
What 6 stages explain how voltage dependent ion channels work for Na+ and K+ ions
- depolarisation starts, threshold of excitation is reached, Na channel opens, changes membrane potential from -70 to +40 mV
- K channels open after slight delay
- Na channels become blocked when AP reaches peak (40mV) - no more can enter
- K+ ions move out of cell, bring membrane potential back to resting potential
- K channel closes, Na channel resets
- membrane potential overshoots its resting -70mV and hyperpolarisation occurs as a result of extra K+ ions outside of axon. These diffuse away and resting membrane potential is restored
What is the all or none law?
once AP begins, it proceeds without decrement to terminal buttons (either occurs or doesn’t)
What is rate law?
variations in the intensity of a stimulus are represented by variations in the rate at which that axon fires
rate of firing causes stronger muscles contraction
Is the all or none law supplemented by rate law?
Yes
What is saltatory conduction?
conduction of APs by myelinated axons
AP appears to jump from one node of Ranvier to next
What are the 2 advantages of saltatory conduction?
economy - less energy used by the Na-K pump (located only at nodes of Ranvier)
speed - conduction much faster in myelinated axon
What is the synapse?
junction between 2 neurons
primary means of communication between 2 cells
What is the synaptic cleft?
Narrow gap (20nm) between neurons
can action potential cross the synaptic cleft?
No - are carried by neurotransmitters (chemical components)
What is the pre-synaptic neuron?
neuron sending impulse
What is the post-synaptic neuron
neuron receiving impulse
Where are neurotransmitter made and stored?
made in pre-synaptic neuron
stored in synaptic vesicles at end of axon
What are neuroreceptors?
chemical gated ion chemicals on the membrane of the post-synaptic neuron
Do neuroreceptors have specific binding sites for neurotransmitters?
yes
neurotransmitters fit binding sites with lock and key mechanism
What are the 2 ways that transmitter-dependent ion channels can be opened?
direct - inotropic receptor - opening from outside
indirect = metabotropic receptor - opening from inside (like ringing a bell to get attention)
Is the exposure of a neurotransmitter to a receptor prolonged or brief?
brief
How are molecules of neurotransmitters destroyed?
Enzymes
What is an excitatory postsynaptic potential (EPSP)?
excitatory depolarisation of postsynaptic membrane
What is inhibitory postsynaptic potentials (IPSP)?
inhibitory hyperpolarisation of postsynaptic membrane
How is the nature of a postsynaptic potential determined?
determined by postsynaptic receptors
What are the 3 major types of ion channels and do they exhibit EPSP or IPSP?
Na+ = EPSP K+ = IPSP Cl- = IPSP
What is neural integration?
process by which inhibitory and excitatory postsynaptic potentials summate and control the rate of firing of a neuron
What type of effect do most neurotransmitters have?
Both excitatory and inhibitory
Which 2 neurotransmitters get most of the synaptic communication done?
glutamate = excitatory effects GABA = inhibitory effects
Which neurotransmitter mainly does synaptic communication in the spinal cord? What is its effect?
Glycine = inhibitory effect
What are most neurotransmitters responsible for?
Having modulating effects
Tend to activate/ inhibit entire circuits of neurons that are involved in particular brain functions
What is psychopharmacology?
Study of effects of drugs on NS and behaviour
What are drug effects?
The changes a drug produces in an animal’s physiological processes and behaviour
What do most drugs affect in the NS?
Synaptic transmission