Cognitive/Motor Flashcards
Primary visual cortex
Large RFs, spatial features and motion.
Parietal visual stream
Small RFs, simple image features such as oriented line segments.
Temporal visual stream
Large RFs, complex image features
Polymodal
visual and other sensory modalities are combined.
Object recognition:
Faces in the temporal lobe
Describe the importance of the pupillary reflex?
If there is a serious brain injury and a increase in pressure (bleeding), the only place where the brain can only get pushed out of the base of the skull, squishing the midbrain and surrounding nerves, impacting the proper functioning of the pupillary reflex
Frequency
Number of cycles per second = pitch (hertz)
Amplitude
loudness
Decibels
sound pressure/reference pressure
Whisper occurs at what dB
0-20
Conversation occurs at what dB
20-40
Conversation occurs at what dB
20-40
Heavy Traffic occurs at what dB
40-60
Live Rock occurs at what dB
80-100
Discomfort occurs at what dB
100-120
Pain occurs at what dB
140-160
The three layers on the normal audibility curve
Threshold, damage threshold, and pain
damage threshold
90 dB
How does maximum listening time per day change with volume level?
As volume increases, the listening time significantly decreases
What is Presbycusis?
The progressive, bilateral hearing loss with increasing age, mainly for frequencies > 1000 Hz
Where basilar membrane motion is converted into neuronal activity
the organ of corti
Deflection of basilar membrane produces
hearing of hair cell stereocelia
Where are the neurons that detect pressure waves found?
The cochlea
What do pressure waves do to the tympanum membrane?
Move back and forth
Move back and forth
Outer hair cell “electromotility”
- Shorten when depolarized
- Lengthened when hyperpolarize
What do the muscles between the tympanum membrane and the oval window do when you speak?
They contract to reduce mechanical coupling between tympanum membrane and oval window to protect cochlea -> protect the ear
Otoacoustic emissions
used to evaluate hearing in newborns
Hair cells contain what type of receptor
Hair cells contain mechanoreceptors
What connects each stereocilia?
Tip links
Tip links
gate ion channels in the stereocilia
What is the cochlear amplifier?
Outer hair cells shorten when depolarized, lengthen when hyperpolarized.
Hair cell electromotility augments basilar membrane motion, allowing for amplification of certain frequencies (like trying to listen to someone at a party)
Mechano-transduction at tip link
activates afferent neurons
Tinnitus
Ringing in your ears
Two types of tinnitus
Transient and Chronic
Transient tinnitus
(< 24 hours)
- Usually due to loud noise.
- Excessive mechanical stress of stereocilia. - Tip-links are thought to break, but
eventually grow back (ringing stops).
Chronic tinnitus
- Many causes, but predominately loud noise. - Origin can be either inner ear, nerve or
central pathways. - Impacts quality of life (does not stop
How do cochlear implants work?
Implanted through round window, electrode placed in scala tympani, directly interact with 8th cranial nerve
Visual transduction
Photons: high energy but hard to catch (~100X106 photoreceptors)
Trillions of opsin molecules
Slow: G-protein cascade
Amplification: one photon closes many ion channels
Auditory transduction
Sound waves: low energy but all around (~15,000 hair cells)
Several hundred thousand tip links
Fast: direct channel activation
No amplification of the transduction
Central auditory pathways
Primary auditory cortex
Thalamus
Midbrain
Medulla
8th cranial nerve (vestibular and auditory)
Cochlear Implant steps
1) Implanted through round window
2) Electrode placed in scala tympani
3) Electrodes are spaced along the cochlear spiral to stimulate groups of afferent fibers that respond to different frequencies.
Generally ~12 electrodes.
Vestibular ocular reflex
eyes rotate in opposite direction
head rotates
gaze does not change
vestibular system
includes the parts of the inner ear and brain that process the sensory information involved with controlling balance and eye movements.
One key similarity between the auditory and vestibular system
Tip links gate ion channels in the stereocilia
Organization of semicircular canals at rest vs rotation of the head
stereocilia bend
Utricle and saccule detect
linear acceleration
How many taste buds do you have?
about 10000
How many taste buds do you have?
about 10000
5 types of taste
Umani, Salty, Sour, Bitter, Sweet
Central taste pathways
Ipsilatory gustatory cortex
Thalamus
Medulla
Cranial Nerves
Olfaction
Smell
Salty channels
sodium moving through channel
Sour channels
Sodium and hydrogen move through channel then potassium is pumped back across against hydrogen
Bitter channels
Bitter blocks potassium channels
various G-protein cascades
Sweet channels
G-protein cascade
Umani channels
Glutamate receptors
G protein cascade
Olfactory signal transduction
Ordorant binding to orderant receptor
G protien activation
Opening of ion channel
How many orderant receptors?
1000
Central olfactory pathways
Olfactory bulb to Olfactory tract to Olfactory receptor cells to nerve to limbic system
Consciousness is measured by
behavior and brain activity
State of consciousness
level of arousal (awake, asleep, etc.)
Conscious experience:
thoughts, feelings, desires, ideas, etc.
Where is the reticular activating system located and what is its function?
In brain stem, helps regulate circadian rhythm
The electroencephalograph (EEG)
Mainly measures activity of neurons located near the scalp in the
gray matter of the cortex.
EEG Frequency
is related to
levels of responsiveness.
EEG amplitude
is related to synchronous neural activity
EEGs reflect
mental states
What does GABA do?
Inhibit release of other neurotransmitters
What is the pathway responsible for motivation?
Mesolimbic dopamine pathway
Alpha rhythm
relaxed with eyes closed
slow frequencies
Beta rhythm
alert
fast frequencies
Awake rhythm
Low amplitude and high frequencies
How many stages of NREM
4
NREM
slow wave sleep
REM
paradoxical sleep
As you go from stage 1 to 4 what changes?
amplitude increases
frequency decreases
How long does it take for stages 1-4 of NREM to occur?
30-45 minutes
Sleep apnea
sudden reduction in respiration
At REM what happens to eye and neck movements
Increased eye movement
Increased inhibition of skeletal muscle (low muscle tone, but twitching can occur)
At REM what happens to the heart and respiration rate?
Increased heart rate and respiration
Regulating States of consciousness involves two parts
Brainstem nuclei that are part of the reticular activating system
- Hypothalamus with circadian and homeostatic centres
what occurs when waking in norepinephrine, serotonin and acetylcholine levels?
increased norepinephrine and serotonin
decreased acetylcholine
State when aminergic neurons are active
waking (reticular activating system)
what occurs to go into REM sleep in norepinephrine, serotonin and acetylcholine levels?
decreased norepinephrine and serotonin
increased acetylcholine
State when cholinergic neurons are active
REM sleep
the reticular activating system is for
Waking or REM sleep
the hypothalamus is for
NREM sleep or waking
What happens to GABA, histamine, and activation of the thalamus and cortex levels during waking?
decreased GABA
increased histamine
increased activation of the thalamus and cortex
increased histamine would result in
waking
What happens to GABA, histamine, and activation of the thalamus and cortex levels for NREM sleep?
increased GABA
decreased histamine
decreased activation of the thalamus and cortex
Motivation
produce goal-directed behavior
Emotions
accompany our conscious experiences
Reward pathway
Mesolimbic dopamine pathway
the primary neurotransmitter in the reward pathway
dopamine
Self stimulation experiments
Continuous activation of reward related areas of the brain.
Mesolimbic dopamine pathway
Prefrontal cortex, midbrain, locus cereleus in the reticular activating system
Emotions system
Limbic system
Limbic system parts of the brain
Olfactory bulb
Amygdala
Hippocampus
Hippocampus
related to memory
What is a declarative memory and what is a procedural memory?
Declarative memory refers to the ability to store and retrieve both personal information (i.e., episodic memory) and general knowledge
Procedural memory is a type of long-term memory involving how to perform different actions and skills
What is an important consolidation method for short term -> long term memory?
Sleep
Where are language parts usually located?
Left hemisphere
Schizophrenia
diverse set of problems in basic cognitive processing. Wide range of symptoms including hallucinations and delusions. Affects one out of 100 people.
What can improve Schizophrenia symptoms
Reducing the effects of dopamine can improve symptoms.
Depression
decreased activity in the anterior limbic system
Treatments of depression
increase the levels of serotonin and
norepinephrine in the extracellular space around synapses.
Bipolar disorder
swings between mania and depression.
Treatments of Bipolar disorder
include lithium that reduces certain synaptic signalling pathways.
Central olfactory pathways leads to the ____ system by ____
limbic system by the olfactory bulb/nerve
What does the odorant bind to and where?
odorant receptors in the cilia
What does the odorant binding activate?
G-protien and opens the ion channels
Consolidation
short-term to long-term
Learning and memory occurs in the
Hippocampus
Short term declarative memory occurs in
Hippocampus and other temporal lobe structures.
Long term declarative memory occurs in
Many areas of association cortex
Short term procedural memory occurs in
Widely distributed
Long term procedural memory occurs in
Basal nuclei
Cerebellum
premotor cortex
Language hemisphere
Left
What is Aphasia?
Language deficit
What is Aphasia?
Language deficit
What are the main functions of Broca’s area and Wernicke’s areas?
Articulation and comprehension
Wernicke’s area
Comprehension of language
Parietal damage
Damage to the right parietal lobe can result in neglecting part of the body or space, which can also impair drawing ability.
What can parietal damage lead to?
Sensory neglect - an inability to attend to sensory information, usually from the left side of the body, as a result of brain injury, most often to the right hemisphere. Contralateral effect (if not producing left side of input, have damage to right side)
Motor behaviour can be
Purposeful or goal directed
What are the two types of motor behavior?
Voluntary and Reflective (due to efferents leaving CNS)
What happens to the antagonist muscle when the agonist contracts?
Relaxes, and vice versa
Agonist and Antagonist Extension muscles
Agonist: Extensor muscle contracts
Antagonist: Flexor muscle relaxes
What type of neurons are motor neurons?
Only excitatory
Increase the angle around the joint
Extension
Limb position is maintained by a
balance of flexor and extensor muscle tension
What are the two types of motor neurons?
Alpha - innervates skeletal muscle
Gamma - innervate muscle spindle (intrafusal)
Motor neurons receives input mostly from
interneurons
Cell bodies of motor neurons are in
ventral horn of spinal cord (spinal nerves) or brain stem (cranial nerves)
Spinal interneurons: descending pathways control
Voluntary movements
Spinal interneurons: other spinal levels
Coordinates complex movements
Spinal interneurons: joint receptor
Proprioceptive feedback
Spinal interneurons: skin receptor
Pain
Spinal interneurons: tendon receptor
Tension
monitoring
Spinal interneurons: muscle receptor (from antagonistic muscle)
Length monitoring
Ascending sensory information moves through
dorsal columns
Motor neuron is in the
ventral horn
Motor efferent
in ventral root
What is the purpose of the withdrawal reflex?
Protects limbs from injury
What is the purpose of the stretch reflex?
Control muscle length
Monosynaptic (primary) or polysynaptic (secondary)
What is the purpose of the inverse stretch reflex?
Controls muscle tension
T/F: Spinal reflexes can be overridden and modified
Most spinal reflexes can be overridden
Flexion withdrawal reflex on the ipsilateral
- inhibition of
- excitation of
- Inhibition of motor neurons innervating the ipsilateral extensor
- Excitation of motor neurons innervating the ipsilateral flexor
Flexion withdrawal reflex on the contralateral
- inhibition of
- excitation of
- Inhibition of motor neurons innervating the contralateral flexor
- Excitation of motor neurons innervating the contralateral extensor
Magnitude of withdrawal reflex depends on the
magnitude of pain stimulus
In the withdrawal reflex, limb withdrawal persists even after removal of the painful stimulus because of
Feedback loops in the spinal cord
Afterdischarge:
Response maintained after stimulus termination (spinal feedback loops)
Irradiation
distance of limb withdrawal
Increase in rate and magnitude of withdrawal response with increased stimulus strength (recruitment of interneurons).
Is the withdrawal reflex poly or mono-synaptic?
Polysynaptic
Monosynaptic stretch reflex
knee jerk
Knee jerk is due to excitation/inhibition of motor neurons in the ipsilateral extensor
excitation
Knee jerk is due to excitation/inhibition of motor neurons in the ipsilateral flexor
inhibition
Why do doctors check the stretch reflex?
To make sure descending pathways and components of the nervous system is working properly
Muscle spindle is in series/parallel with extrafusal muscle
parallel
Extrafusal muscle fiber is activated by
alpha motor neurons
Intrafusal muscle fiber is activated by
gamma motor neurons
What does the golgi tendon organ do?
is a proprioceptor – a type of sensory receptor that senses changes in muscle tension
What happens to the muscle spindle as the muscle stretches or shortens?
It is in parallel with the muscle, therefore it does the same thing
What type of muscle fibers are adapting and non-adapting?
IA are adapting (dynamic changes in muscle length)
II are non-adapting (signal static muscle length)
Are alpha and gamma neurons activated together?
Yes, alpha-gamma coactivation
What are the 3 properties of the stretch reflex?
Resists changes in muscle length (muscle tone (clinical term))
Mono and poly-synaptic components
Feedback from muscle spindles
What are the properties of muscle spindles (6):
Reports muscle length
In parallel with extrafusal muscle fibers
IA primary: detects changes in muscle length and some static length (nuclear bag fibers)
II secondary: detects static length (nuclear chain fibers)
Intrafusal fibers: maintain muscle spindle sensitivity
Alpha-Gamma coactivation
What type of afferents carry information from the golgi tendon organ to the spinal cord?
IB afferents
Muscle spindles afferents
la primary
la secondary
nuclear bag fibers
la primary
nuclear chain fibers
la secondary
dynamic changes in muscle length (and some static length)
Ia primary
signal static muscle length
II secondary
Muscle spindles can
lose sensitivity when muscle spindle collapses in voluntary flexion
Muscles in extension
Muscles are lengthen
Muscles in voluntary flexion
Muscles are shorten
Extension/Voluntary flexion: Increase in muscle spindle afferent activity
Extension
Extension/Voluntary flexion: Muscle spindle collapses
sensitivity is reduced
Voluntary flexion
Extension/Voluntary flexion: intrafusal fibers contract and muscle spindle is stretched
Voluntary flexion
How is spindle sensitivity maintained?
Intrafusal fibers contract and muscle spindle is stretched
What is the role of the middle level of motor control?
Executes the individual muscle contractions (to perform complex movement)
Makes corrections based on sensory information
Active contraction of a muscle produces more ______ than ______
(stretching, tension)
tension than stretching
Golgi tendon organ responds to
tension
Golgi tendon is in (series/parallel) with the muscle
series
Golgi tendon organ structure
Capsule
Ib afferent
Free nerve ending
collagen fibers
Properties of Golgi tendon organ
1) Reports muscle tension.
2) In series with extrafusal muscle fibers.
3) Ib afferents.
4) Underlies inverse stretch reflex (polysynaptic).
T/F: Voluntary movements do not have an “involuntary” component
F: Voluntary movements have an “involuntary” component
Where is the decision to execute a movement initiated?
Frontal cortex
What is the pattern of decision for voluntary control of movement in brain?
Consciously initiating a movement happens in the frontal cortex. After about 100 msec, this idea moves to the premotor area of cortex then to primary motor cortex. After, activity goes down towards brain stem and spinal cord
What area of the body are governed by which part of the primary motor cortex (from lateral to top of head (medial)?
Head, arms, trunk, legs
What is the relationship between the size of the body structures in primary motor cortex and number of neurons dedicated to their motor control?
Increase together (mouth and hands for example have a lot of real estate in the primary motor cortex)
What does the corticospinal pathway dictate?
Skilled movements
Extrapyramidal
trunk & posture
Corticospinal is from ________ to ____ and ______
from sensorimotor cortex to brainstem and spinal cord
What is the overall effect on the basal nuclei in Parkinson’s disease?
Reduced dopamine input to basal nuclei
Muscle tone
Resistance of skeletal muscle to stretch.
What are the 4 symptoms of parkinsons?
Akinesia: reduced movements
Bradykinesia: slow movements
Muscular rigidity
Resting tremors
What is Huntington’s disease and its cause?
Widespread loss of neurons in the brain
Neurons in basal nuclei are preferentially lost
What are the 2 disorders/symptoms that come with Huntington’s disease?
Hyperkinetic disorder: excessive motor movements
Choreiform movements: jerky random involuntary movements of limbs and face
Hypertonia
Abnormally high muscle tone.
Hypotonia
Abnormally low muscle tone.
Spasticity
Overactive motor reflexes.
What is deep brain stimulation?
Treatment for parkinsons, stimulation of globus pallidus/basal nuclei via surgically implanted electrode
Reduce symptoms of parkinsons
Rigidity
Constant muscle contraction.
Atrophy
Loss of muscle mass
Helps to determine the specific sequence of movements needed to accomplish a desired action.
Basal nuclei
Where are nearly half the neurons in the brain found?
Cerebellum
What information does the cerebellum receive?
Sensory info -> vestibular, visual, auditory, somatosensory, proprioceptive
Treatment for Parkinson disease
increasing dopamine concentrations in the brain
What is asynergia?
Cerebellar deficit, smooth movements are subdivided into their separate components
What is dysmetria?
Cerebellar deficit, Unable to target movements correctly ‘past pointing’
What is ataxia?
Cerebellar deficit, Incoordination of muscles group (awkward gate)
What is intention tremor?
Cerebellar deficit, involuntary tremors during voluntary movements
