Background info Flashcards
Are neurons somewhat synchronized in regular firing rhythms, known as “brain waves”?
yes
Where are electrodes placed?
On the scalp and in pairs
What are EEG signals affected by?
cerebral cortex’s state of arousal
Do EEGs show slow or fast changes in membrane potentials?
Slow
Where do EEG waves arise
thalamus
Name a location of an input that affects this location
the brainstem reticular
formation
Alpha
- (8-13 Hz; 30-50 uV avg. amplitudes)
- relaxed state and eyes are closed
How are alpha waves decreased?
eye opening + mental effort
Alpha waves: Cortical activatiion relationship
greater activation = lower alpha activity
Strong areas of alpha waves
occipital and frontal cortex
Beta
- (13-30 Hz; < 20 uV)
- Awake, alert, eyes open
How are beta waves decreased?
absent or reduced in areas with cortical damage + sedative-
hypnotic drugs
Theta
- (4-8 Hz; < 30 uV)
- awake children up to adolescence; can’t been seen in adults; seen in sleep at all ages
Low theta
- (4-5.45 Hz)
- Activities with decreased arousal & increased drowsiness
High theta
- (6-7.45 Hz)
- tasks involving working memory
Delta
- (0.5-4 Hz; up to 100-200 uV)
- sleep stages 3 and 4 (not seen in conscious adult)
- Highest amplitude out of all EEG waves
- Jaw/neck muscles movement make these waves as well
Gamma
- (30-50 Hz)
- Higher mental activity association, disappears under general anesthesia
- Enhanced in monks because of meditation, absent in schizophrenics
The more active the brain, the ____ the frequency and the _____ the amplitude of the EEG
- higher, lower
- The inverse holds true
What are the two states of sleep?
REM and non-REM
How many phrases does non-REM sleep have? Is it progressive?
Yes, it is progressive, N1-N3
How long does the REM cycle last?
about 90 minutes
About how many times does the REM cycle repeat in a span of 8 hours?
4-6 times
What happens during the latter REM cycle?
REM component gets longer while N3 gets shorter/not
occurring
N1
- Decreased beta activity
- Alpha activity less obvious
- Theta activity emerges
N2
- Irregular theta activity
- Sleep spindles (12-14 Hz) in short bursts
- Wave amplitude (K-complexes) suddenly increase
N1 and N2 are the?
“light” stages
N3 is known as the?
“deep sleep” stage
Non-REM
- Increased serotonin
- Secretion of norepinephrine, corticosteroids and testosterone (males)
- Blood pressure decrease
What are the five main regions of the brain?
Cerebral Hemispheres
Cerebellum
Diencephalon
Brainstem
Spinal Cord
Cerebral Hemispheres
- Makes outer surface
- Has numerous grooves
- Superficially divided into lobes
Functions of the cerebral hemispheres
- Reasoning
- Abstract thought
- Audio/visual processing
- Memory
Cerebellum
- Location: base of brain
- More specific: below cerebral cortex & behind brainstem
Functions of cerebellum
- Planning/timing of movement
- Motor memory
- Posture
Functions of Diencephalon
- Sensory input receiver
- Distributes info to where it needs to go
- Regulates autonomic & endocrine systems
Brainstem
- Location: Base of skull, continues with spinal cord
Parts of the brainstem
i. Midbrain
ii. Pons
iii. Medulla oblongata
Functions of the brainstem
- Sensory-motor relay
- Autonomic function regulation
Spinal Cord
Continuation of brainstem
Function of the brainstem
Sensory and motor info relay
1. Originates from:
a. Cerebral cortex
b. Cerebellum
- Brings to:
a. Organs
b. Limbs
How many divisions are there in the cerebrum?
2 (left and right hemisphere)
What connects the hemispheres of the cerebrum?
white matter tract called the corpus callosum (the biggest
white matter structure in the brain)
What is Agenesis?
a disorder in the corpus callosum where a baby is born with part or
all of their corpus callosum missing.
Symptoms?
Holding head up
Sitting, standing, walking
Poor hand-eye coordination
Seizures
Feeding problems
Impaired mental/physical development
Poor visual & auditory memory
Cerebral Cortex
Comprises the (outer/inner) layer (gray matter) of the brain.
Higher brain functions of the cerebral cortex include:
- Reasoning
- Abstract thought
- Language
What are the four lobe subdivisions of each hemisphere of the cerebral cortex?
o Frontal
o Parietal
o Occipital
o Temporal
Where is the primary motor cortex?
at the posterior border of the frontal lobes
What nerve impulse initiation occurs? (frontal lobe)
movements
Areas of “Executive functioning” for the frontal lobe
o Abstract thought
o Planning
o Consequences of actions
o Learned social behaviors
Prefrontal cortex plays what significant role?
working memory
What is involved in language expression?
Broca’s area
What symptoms would you see in a person if Broca’s area is damaged?
Expressive
aphasia: difficulty in speaking in complete sentences but not impaired in language
comprehension
What is in the parietal lobe?
the somatosensory cortex
What does the parietal lobe do?
integrates various sensory information such as
Auditory
Visual
Somatosensory (sensations that can occur anywhere in the body (i.e. pressure,
heat, or pain)
Proprioceptive (the sense of where the body is in relation to itself and its
surroundings)
What is the sensory homunculus?
a representation of the location of the different regions of
the body
What is in the occipital lobe?
the visual cortex
What symptoms would you see in someone whose occipital lobe has been damaged?
varying degrees and types of visual impairment despite the eyes being undamaged. This includes:
o Unable to distinguish colors
o Visual hallucinations
o Blindness
What is in the temporal lobe?
the auditory cortex
What does the temporal lobe do?
receive and process auditory information
What is involved in understanding language?
Wernicke’s area (Don’t confuse with Broca’s
area, which is involved in language expressions)
What symptoms would you see in someone whose Wernicke’s area has been damaged?
Receptive aphasia: unable to understand language, both spoken and written;
however, patients can still speak with normal fluency but may be meaningless or
unintelligible
Why is the cerebellum (“little brain”) important?
used for smooth, coordinated, and precise
movements
Where is the cerebellum located?
behind the pons and midbrain (these two are part of the
brainstem)
How many % of all neurons of the brain are here?
50%
How is the cerebellum able to perform its functions?
processes information received from other areas of the brain such as:
Vestibular
Visual
Somatosensory
Motor
What is the cerebellum involved in?
posture and balance
Without using medical equipment, what is a simple way you can assess a person’s cerebellar
function?
- examination of one’s gait
- balance (eyes open and then shut)
- “finger to nose” testing
- Will have difficulty when asked to perform accurate rapid alternating movements (i.e. touching own nose and then the examiner’s finger or showing how to screw a lightbulb
into a socket)
What is a reflex?
an involuntary movement in response to a stimulus, occurring almost
immediately after the stimulus
Myotatic
- related to a muscle stretch reflex
- A type of simple spinal reflex
How are stretch reflexes produced?
single synapses between sensory axons and motor
neurons
How many neurons are used for stretch reflexes? Provide an example
two; hitting the patellar
ligament below the patella will stretch the quadriceps muscle
What does a stretch reflex trigger?
impulse in a sensory axon
Where is the sensory axon cell body located?
the dorsal root ganglion in the lumbar region of
the spinal cord
What is the sensory axon directly next to?
a motor neuron
What does a sensory axon do?
triggers an action (i.e. after the patellar ligament is struck an impulse
sent from the sensory axon will go to the motor neuron and will trigger contraction)
True or False: the brain is necessary and required for many simple reflex functions
FALSE
How many synaptic links does the protective reflex require to function?
– Several
- Yet we are able to withdraw from painful stimuli at fast speeds!
Map out the pathway of the protective reflex
stimulation of nociceptive (pain) sensory
neurons occurs -> flexor muscles stimulated -> withdrawal of stimulated limb
What happens at the same time of the protective reflex?
extensor muscles in the opposite limb is inhibited
crossed extension reflex
helps to enhance postural support during withdrawal
Describe the phenomenon as said by Joseph Babinski
When the sole of the foot is stroked in
patient with an upper motor neuron lesion, the big toe dorsiflexes (extends upwards)
What is the importance of the babinski phenomenon?
used to identify disease or damage to the spinal cord or brain
Where is the babinski also seen in?
infants younger than 12-18 months
Who and how is the Babinski Sign inhibited?
in healthy adults and children, the cerebral cortex
inhibits by the big toe flexes (curl downwards) and eversion of the foot (this is called plantar
reflex)
If lesions in neurons are found, what are the ones that affect ability to contract muscles?
upper motor neuron lesions
Findings on affected limbs:
Spasticity
“Clasp knife rigidity” (initial resistance to movements initiated by the observer,
followed by relaxation)
Muscle weakness with moderate wasting
Hyperreflexia (i.e. tendon jerk reflexes)
Babinski sign
What type of neuron lesion is present when cell bodies of the motor neurons in the anterior horn of spinal cord are damaged?
lower motor neuron lesions
Findings on affected limbs:
Paralysis or muscle paresis (partial loss of movement)
Muscle weakness w/ significant wasting
Spontaneous contractions of groups of muscle fibers (fasciculations), visible on
physical examination
Spontaneous contractions of individual muscle fibers (fibrillations), not visible
on physical examination
Hypotonia or atonia
Areflexia or hyporeflexia
No Babinski sign
An abnormal reflex when detected in people over 2 years of age, but normal in children under
this age
Babinski sign
Closing of the eye to protect it from foreign objects, bright light, or other perceived hazards.
corneal (blink) reflex
Constriction of the pupils to view near objects
accommodation reflex
Involves the removal of a limb from painful or threatening stimuli
flexion withdrawal reflex
Modification of the pupil’s diameter in response to light
pupillary light reflex
Occurs in conjunction with the flexion withdrawal reflex to provide postural support.
crossed extensor reflex
What is the correct order for the pathway in a flexion withdrawal reflex arc?
Receptor -> sensory neuron -> interneuron -> motor neuron -> muscle
In the pupillary reflex, which of the statements are true?
The optic nerve is responsible for carrying light information to the midbrain.
The oculomotor nerve carries the efferent response from the midbrain.
The oculomotor nerve innervates the circular muscle of the iris.
In the pupillary reflex, which of the statements are false
The reflex is monosynaptic
In the pupillary reflex, what happens when a light is shined on the eye?
The circular muscle of the iris contracts in both eyes
Upper motor neuron lesion signs
- Increase in muscle tone (spasticity)
- Brisk tendon jerk reflexes
- The big toe extends upwards when the sole of the foot is stroked
- There is muscle weakness with no wasting
Lower motor neuron lesion
- Hypotonia or atonia
- No Babinski sign
- Muscle tone is decreased
How does a pulse transducer work?
The pulse transducer detects the pulse, a pressure wave created by each heartbeat following the expansion and recoil of arteries
Why would there be a lag between the raw data signal and the channel calculation signal that you see on screen?
The channel calculation like other computer systems needs time to convert the raw data they’re receiving into data that is readable by the channel.
A fluid membrane is composed of?
phospholipids, proteins, and other molecules surrounds all cells
Function of a membrane
- regulates what comes into and out of the cell.
- The structure must facilitate communication with other cells, uptake of nutrients, and disposal of wastes.
amphipathic molecules
they have a hydrophobic region and a hydrophilic region
Phospholipid tail
orient themselves towards the inside of the sheet and each other; hydrophobic
Phospholipid heads
form hydrogen bonds with the aqueous solution and point outwards into it; hydrophilic
Transmembrane proteins are primarily composed of
- non-polar amino-acids that span the bilayer
- They have a diverse range of functions and are commonly involved in cellular signalling processes
Cholesterol
act to strengthen and maintain fluidity of the bilayer and regulate activity of some membrane proteins.
Unsaturated lipids
can cause a disruption in lipid packing, thus making a bilayer which is more permeable to small molecules and has greater flexibility
Why is membrane strength important?
bilayer is held together solely by relatively weak non-covalent hydrophobic bonds and there is no formation of stronger chemical bonds
The color of red beetroot is due to
a purple pigment, betacyanin, and a yellow pigment, betaxanthin.
Beet pigment is contained in?
vacuoles
