Brain & Cognition Flashcards
describe single unit recording.
Electrodes, consisting of thin wire strands, are implanted into specific areas of the brain. Recordings of this brain cell activity are made by measuring the electrical potential of nearby neurons that are in close proximity to the electrode.
too invasive for humnas.
Describe EEG.
Electroencephalography (EEG) is the measurement of the electrical activity of the
brain by recording from electrodes placed on the scalp. The resulting traces are
known as an electroencephalogram (EEG) and represent an electrical signal from a
large number of neurons.
non invasive.
The conversion of the raw EEG from three electrodes (F3, C3 and P3) into the
four classical EEG frequencies: from slowest to fastest (delta, theta, alpha and
beta).
EEG signals represent the temporal profile of the change in the
potential difference between two electrodes placed on the scalp.
what are ERPs?
When populations of neurons are active in synchrony, they produce an electric field that
can be detected at the scalp (EEG). When many waves are averaged and linked to the
onset of the stimulus, then an ERP is obtained
The EEG obtained on several trials can be averaged together
time locked to the stimulus to form an event-related potential (ERP).
ERPs are voltage fluctuations that are associated in time with particular event (visual, auditory, olfactory stimuli) ERPs can be recorded from the human scalp and extracted from the ongoing electroencephalogram EEG by means of filtering and signal averaging.
How can ERP’s be used?
to study facial recognition.
Different ERP peaks associated with different aspects of face processing.
• The N170 is relatively specialized for faces,
recorded from rPSTS sites
• The P300 – famous and familiar faces.
A comparison between the ERPs from patients with Alzheimer’s disease
and those from control subjects. A markedly reduced P300 is seen for the
demented patients at each electrode site
describe MEG.
Magnetoencephalography (MEG) is an imaging technique used to measure
the magnetic fields produced by electrical activity in the brain via extremely
sensitive devices known as SQUIDs. These measurements are commonly
used in both research and clinical settings. Excellent temporal and spatial
resolution.
non invasive
Describe MRI
Uses differential magnetic properties of types of tissue and of
blood to produce images of the brain.
Describe structural MRI scanning
- Detection of brain damage
- Detection of lesion (brain damage) location
- Measurement of lesion extent
- Detection of damage to connections
different types of tissue (skull, gray matter, white matter, CSF
fluid) have different physical properties – used to create STATIC maps (CT
and structural MRI)
Describe functional imaging.
temporary changes in brain physiology associated with cognitive processing (PET & fMRI)
describe CT scans
Computed tomography (CT) scanning
builds up a picture of the brain based on
the differential absorption of X-rays.
CT scans reveal the gross features of the brain but do not resolve its structure well.
Describe PET
Functional imaging.
Positron Emission Tomography (PET) uses trace amounts of short-lived
radioactive material to map functional processes in the brain. When the
material undergoes radioactive decay a positron is emitted, which can be
picked up be the detector. Areas of high radioactivity are associated with
brain activity.
describe fMRI
functional MRI
Neuronal activity requires oxygen and glucose (energy)
• Neuronal activity produces changes in blood oxygenation levels
• fMRI uses the contrast between oxygenated and deoxygenated
blood
• They have different magnetic properties and so fMRI can provide
information about brain activity.
fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.
describe the BOLD response.
blood oxygenation dependent level.
blood flow increases when stimulus is applied.
looks like an action potential.
describe DTI
diffusion tensor imaging.
An imaging method that uses a modified MRI scanner to reveal bundles of
axons in the living brain
We can visualize connections in the brain.
muse 2nd law.
What is TMS?
transcranial magnetic stimulation.
a means of disrupting normal brain activity by introducing
neural noise – ‘virtual lesion’
Michael Faraday.
Faraday’s coil. magnetic field must be changing - ie switching on and off.
Apply TMS pulse at any cortical node of the network, TMS
will interfere with the reading relevant neural signal:
– efficacy of that signal will be degraded
– behavioural decrement (RT change – it will take us
longer to read).
Advantages of TMS: • Interference/virtual lesion technique. • transient and reversible • Control location of stimulation • Establishes a causal link of different brain areas and a behavioural task
best approach to explore brain function?
convergent approach, use various methods at once.
What does Anterior Posterior Dorsal Ventral Lateral Medial Ipsilateral Contralateral Caudal mean?
Anterior Front Posterior Back Dorsal Top Ventral Bottom Lateral Toward side Medial Toward Middle Ipsilateral Same side Contralateral Opposite side Caudal Tail
What is the transverse section?
right angle to the neuraxis.
What is the sagittal section?
parallel to neuraxis and perpendicular to the ground.
What is the horizontal section?
parallel to the ground.
what is in the CNS?
brain and spinal cord.
what is in the PNS?
cranial nerves and spinal nerves.
what allows the passage of the spinal cord?
the foramen magnum
dont need to know
What is the dura mater?
the outermost layer of the meninges.
tough and flexible.
What is the arachnoid?
middle layer of the meninges.
does not dip into the valleys of the brain contour.
What is the pia mater?
last layer of the meninges, adheres to the surface of the brain.
space between arachnoid and pia is filled with Cerebral spinal fluid.
what are ventricles?
a set of hollow chambers filled with CSF. Where it is produced.
2 lateral ventricles
third ventricle
cerebral aqueduct (connects 3 and 4)
fourth ventricle
describe CSF.
Similar to blood plasma composition
• Formed by the choroid plexus
• Forms a watery cushion to protect the brain
• Circulated in arachnoid space, ventricles, and central canal of the
spinal cord
• Total volume of cerebrospinal fluid = 125-150 ml
• The entire volume of cerebrospinal fluid turns over 3 to 4 times
per day
• CSF is actively secreted by the brain. CSF is constantly being
made, circulates and is reabsorbed into the blood stream
What produces CSF?
choroid plexus.
Most created in 3rd ventricle, some in 4th.
what is hydrocephalus?
“water head”
can be due to mother having measels or rubella.
one ventricle gets blocked, usually 3rd.
ventricles get bigger due to excess fluid.
Head gets bigger, skull is still flexible as a baby.
insert a valve to drain to abdominal cavity at the correct pace.
Describe telencephalon.
contains the cerebral cortex, basal ganglia and the limbic system.
located in the forebrain in the lateral ventricle.
describe diencephalon.
contains the thalamus and hypothalamus.
located in the forebrain in the third ventricle.
describe mesencephalon.
contains the tectum tegmentum.
located in the midbrain in the cerebral aqueduct.
describe metencephalon
contains the cerebellum and pons.
located in the hindbrain in the fourth ventricle.
describe myelencephalon.
contains the medulla oblongata, loctaed in the hindbrain in the fourth ventricle.
describe the forebrain.
largest section of the brain, contains the telencephalon and diencephalon.
describe the cerebral cortex.
thin layer of tissue covering the brain consisting of two hemispheres.
what are the bumps and grooves on the brain?
gyrus - bump
sulcus - groove.
what is grey matter?
composed of cell bodies of the neurones.
what is white matter?
axons and dendrites of the neurones, myelinated
how do the two hemisphers communicate?
through the corpus callosum.
how do you remember the location of the lobes?
FPOT.
frontal parietal occipital temportal
going clockwise around.
what is a fissure?
a very large deep groove.
where is the central fissure?
sylvian
occiptal
exoociptal??
central fissure between frontal and parietal lobe.
sylvian between temportal and frontal.
occiptal between parietal and occiptal
look up pic
what are the primary coritices?
involved in senses and motor functions.
where is the primary visual cortex?
in the occipital lobe at the back of the head.
where is the auditory cortex?
superior temporal gyrus.
superior, medial, inferior?
when locating something, how high up???
what seperates the primary motor cortex and the primary somatosensory cortex?
central sulcus
what does the primary motor cortex do?
Neurons in different regions of the motor cortex connect to muscles in different regions of the contralateral side of the body
what does the primary somatosensory cortex do?
It receives information from the body senses; different regions receive information from different parts of the body.
what is a brodmann area?
a region of the cerebral cortex based on it’s structure n shit.
what is the limbic system?
set of structures involved in learning, memory, and emotion.
telencephalon
contains: Limbic Cortex Hippocampus Amygdala Fornix Mammillary Bodies (part of the hypothalamus)
describe the basal ganglia.
telencephalon.
set of structures involved in processing information for motor movement. Major structures of the basal ganglia motor system include:
•Caudate Nucleus
•Putamen
•Globus Pallidus
What does the Thalamus do?
diencephalon. forebrain
Main sensory relay for all senses (except smell) and the cortex.
Lateral GN and Medial Geniculate Nucleus
What does the hypothalamus do?
diencephalon. forebrain
set of nuclei involved in regulating the autonomic nervous system, controlling the pituitary gland.
describe the midbrain.
mesencephalon - comprised of the tectum and tegmentum.
tectum - roof
tegmentum - covering
describe the tectum.
mesencephalon.
contains: 1. superior colliculi – subcortical sensory pathway involved in fast eye movements (vision) 2. inferior colliculi - part of auditory pathway
Describe the tegmentum
mesencephalon.
role in motor movement
- reticular formation (sleep and wake cycles)
- red nucleus (movement)
- substantia nigra (movement) can lead to parkinsons if damaged.
describe the hindbrain.
Contains both the metencephalon and the myelencephalon.
describe the cerebellum.
• appears as a mini brain
• involved in motor coordination and
smooth execution of movement
describe the pons.
- part of the reticular formation
- involved in sleep and arousal
- link between cerebllum and cerebrum
describe the medulla oblongata.
myelencephalon.
involved in basic life functions, such as breathing, swallowing, heart rate and wake-sleep cycles.
describe the spinal cord.
CNS tissue extending caudally
from the medulla in the brain
The spinal cord communicates with
the sense organs and muscles
below the level of the head
Primary Components of the Spinal
Cord:
• Dorsal Roots
• Ventral Roots
white matter on the surface, grey matter on the inside.
how is matter arranged in the brain?
white matter in the centre, grey matter on the surface.
describe dorsal roots.
afferent, carry sensory info to the CNS
describe ventral roots.
carry motor info to the muscles and glands, efferent.
away from the CNS
describe the peripheral nervous system.
Located outside of the skull and spine.
It comprises of two parts: the somatic and the autonomic nervous systems.
Brings information into the CNS and carry signals out of the CNS.
somatic nervous system?
The part of the peripheral nervous system that controls the
movement of skeletal muscles or transmits somatosensory
information to the central nervous system
autonomic nervous system?
The portion of the peripheral nervous system that controls the body’s vegetative functions.
describe cranial nerves.
12 motor/sensory nerves attached to the ventral surface of the brain.
efferent motor, afferent sensory.
describe spinal nerves.
peripheral nerves attached to the spinal cord.
31 pairs
afferent and efferent travel to muscles and sensory receptors.
autonomic nervous system?
all nerves are efferent.
Regulation of smooth muscles, cardiac muscle and glands.
Comprised of the sympathetic and parasympathetic divisions.
Sympathetic and parasympathetic nerves generally have opposite effects.
Sympathetic
“Fight or flight”
Arousal and preparing the body
for the expenditure of energy
Parasympathetic
“Rest and restore”
Relaxing the body
what is the cell body?
soma
describe the types of neurones.
Sensory neurons- detect changes in external and internal environment (CNS and
PNS, light, sound, odours, touch…).
Motor neurons- controls muscle contraction and also gland secretion (CNS and
PNS).
Interneurons- lie entirely within the CNS and are involved in cognition
(i. e.,perceiving, learning, remembering and executive functioning such as decision
making) .
describe multipolar neurons
neuron with one axon and many dendrites attached to its soma.
describe bipolar neurons
neuron with one axon and one dendrite attached it its soma.
dsecribe unipolar neurons
neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous. system.
what forms myelin sheaths?
oligodendrocytes. CNS
schwann cells PNS
what do astrocytes do?
form support for CNS.
help form the blood brain barrier.
secrete neurotrophic factors.
take up K+ NT.
• “Star cells” • Provide physical support to neurons • Provide nourishment • When neurons die they clean up debris and form scar tissue • Control chemical composition of fluid surrounding neurons
what do microglia do?
modified immune cells
act as scavengers?
what do ependymal cells do?
create barriers between compartments.
source of neural stem cells.
what is the blood brain barrier?
A semipermeable barrier between the CNS and circulatory system, which helps to regulate the flow of nutrient rich fluid into the brain.
what is the area postrema?
a region of the medulla where the blood-brain barrier is weak. This allows toxins in the blood to stimulate this area,
which initiates vomiting – poison expelled from the body.
what is the membrane potential?
electrical charge across a cell
membrane; the difference in
electrical potential inside and
outside the cell.
resting potential?
membrane potential of a neuron when it is not being altered by excitatory or inhibitory postsynaptic potentials, normally about -70 mV.
depolarization?
reduction (toward zero) of the membrane potential when we stimulate neuron
action potential yo
ye
describe electrostatic pressure.
when substances dissolve in water, they
split into 2 parts with opposing electrical charge Na + and Cl− : IONS.
Attraction of oppositely charged ions (+-) and repulsion of similarly charged ions (++; - -) is exerted by electrostatic pressure
what is the Direct opening of ion channel?
an ionotropic receptor.
what is the indirect opening of an ion channel?
metabotropic receptor.
what is an EPSP?
excitatory depolarization of the postsynaptic membrane.
Excitatory Postsynaptic Potential
what is an IPSP?
Inhibitory Postsynaptic Potential.
inhibitory hyperpolarization of
the post synaptic membrane.
describe Na K and Cl
Sodium (+) EPSP
Potassium (+) IPSP,
Chloride (-) IPSP
what effect does glutamate have?
excitatory
what effect does GABA and glycine have?
inhibitory
also in the spinal cord
what is an antagonist?
A drug that opposes or inhibits the effects of a particular neurotransmitter on
the postsynaptic cell.
what is an agonist?
A drug that facilitates the effects of a particular neurotransmitter on the
postsynaptic cell.
what is an indirect agonist/antagonist?
A drug that attaches to a binding site on a receptor and facilitates the action of the receptor; does not interfere with the binding site of the principal neurotransmitter
what is a direct agonist/antagonist?
A drug that binds with and activates
(opens or blocks) a receptor. This drug
mimics the neurotransmitter
how can reuptake be prevented?
In the first case the drug attaches to the transporter molecules that are responsible
for reuptake and inactivate them - blocking reuptake.
In the second the drug bind with the enzyme that normally destroys the
neurotransmitter and prevents the enzymes from working.
Both types of drugs prolong the presence of the neurotransmitter in the synaptic
cleft (and hence in a location where they can stimulate postsynaptic receptors),
they serve as agonists.
describe acetylcholine
The primary neurotransmitter secreted by the efferent axons of the CNS.
All muscular movement is accomplished by the release of acetylcholine.
ACh is involved in regulating REM sleep - dreaming (doroslateral pons), perceptual
learning (basal forebrain), and memory (hippocampus).
ACh receptors: nicotinic and muscarinic
ACh found at the target of parasympathetic branch of the ANS – outside of the CNS,
first discovered neurotransmitter – the importance of Otto Loewi.
The effects of ACh are generally facilitatory
what is a nicotinic receptor?
an ionotropic acetylcholine receptor stimulated by nicotine
what is a muscarinic receptor?
a metabotropic acetylcholine receptor.
produces parasympathetic nerve effects in the heart, smooth muscles and glands.
GPCR
stimulated by muscarine
describe curare.
blocks nicotinic ACh receptors at synpases, causes paralysis.
describe atropine
Atropine prevents Ach from depolarising the postsynaptic membrane and so prevents generation of the impulse in this cell.
describe botulinum toxin
prevents ACh release by terminal buttons, “botox”
antagonist
describe black widow spider venom
agonist, A poison produced by the black widow spider triggers the release of ACh.
what is a cholinergic synapse?
Synapses that have acetylcholine
transmitter are called cholinergic
synapses.
describe the action of a cholinergic synapse.
An action potential arrives at
presynaptic membrane. Voltage gated calcium channels in the presynaptic membrane open, calcium ions enter the presynaptic neuron.
Calcium ions cause synaptic vesicles to fuse with the presynaptic membrane, releasing acetylcholine into the synaptic cleft.
Acetylcholine diffuses cross the synaptic cleft and binds to specific neuroreceptor sites in the post synaptic membrane.
Sodium channels open. Sodium ions diffuse into the postsynaptic membrane causing depolarisation, which may initiate an action potential.
Acetylcholinesterase (enzyme) breaks down acetylcholine.
The products diffuse back into the presynaptic neuron where acetycholine is resynthesised using ATP from the mitochondria.
describe a neuromuscular junction.
Same stages as cholinergic synapses, but in this case the postsynaptic membrane is the muscle fibre membrane (Sarcolemma). Depolarisation of the sarcolemma leads to contraction of muscle fibre.
what is a tolerance?
• A state in which organism no
longer responds to a drug
• A higher dose is required to
achieve the same effect
what is dependence?
A state in which organism functions normally only in the presence of a drug
Manifested as physical disturbance when the drug is withdrawn
what is the nigrostriatal system?
starts in the substantia nigra and terminates in the basal ganglia : plays a role in the control of movement.
degeneration leads to parkinsons
