Exam 2 Flashcards
Neurochemical Method examples
Positron emission tomography (PET) and magnetic resonance spectroscopy (MRS)
What is the main technical limitation to using neurochemical methods?
Their concentration cannot be localized to a very precise degree within brain tissue
How do PET scans work?
They alter molecules to have a radioactive atom (aka radioactive tracer) introduced to the blood and be carried to the brain. The tracer binds to some cells and gives a measure of neurotransmitter function
PET scans are not often used in studies to understand cognitive and emotional function. Which test would be best for that?
FMRI
PET scans are the gold standard for obtaining which type of information?
- absolute measure of regional cerebral brain flow (rCBF)
- cerebral metabolic rate and oxygen consumption
- cerebral glucose metabolism
True or False: MRI can be tuned to specific atoms
True
Which type of scan is best for detecting the presence of Glutamate, GABA, and N-acetylaspartate (NAA)?
MRS
Which is the second most common substance in the brain behind glutamate having high levels in the hippocampus and is predicted to be associated with higher working memory?
NAA
What are two limitations of MRS?
- Spatial resolution is not very good (worse than PET)
- To be detectable, the substance concentration must be quite high
What is a BOLD signal?
BOLD = Blood Oxygen Level Dependent
- based on the fact the oxygenated and deoxygenated blood have different magnetic properties
When using a BOLD signal, are you more likely to pick up a signal with oxygenated or deoxygenated blood?
Oxygenated
-deoxygenated makes the static magnetic field in homogenous, making it more difficult to detect a signal
What type of scan uses a BOLD signal?
FMRI
Advantages of an fMRI
- MRI machines are widely available
- noninvasive
- multiple scans can be run on an individual
- can be used on children and women of reproductive age
- provides a measure of activity over seconds instead of minutes
- can provide info about average patterns of activation across groups of individuals as well as for specific individuals
Faces vs. fixation cross
Reveals all regions of the brain involved in processing
Faces vs. Houses
Reveals only those regions of the brain that are involved in processing the specific configuration properties of faces as compared to other complex objects
What is ROI?
The Region of Interest
Multivoxel Pattern Analysis (MVPA)
- Provides info about the level of activity as well as the pattern across brain regions
Different classes of objects such as furniture, tools, animals, etc. all activate a _________ region of visual cortex
Common
disadvantages of fMRI
- objects cannot be distinguished by the degree of activation alone
- MVPA methods suggest the possibility of brain “decoding”
Resting State fMRI advantages
- doesn’t require a degree of cognitive ability or engagement on the part of the participant
- only takes about 10-15 minutes
resting-state disadvantages to fMRI
- can’t be used for functional task analysis
- usually used as an individual difference variable to compare with some other construct
Modular
Looking at brain regions and their functions
Connective
Looking at connections between regions and networks
When significant relationships are observed, scientists often refer to this phenomenon as ___________ _____________
Functional connectivity
Which brain region is known as the “great integrator”
The Pre-frontal cortex
Graph theory or network analysis is?
A study of the interaction between brain regions can be studied for interrelationship
- Measures how information flows through the system and uses Huns to act as conduits of information.
Which type of scan has the best temporal resolution?
Electroencephalographs (EEG)
How quick can an EEG measure brain activity
On a millisecond to millisecond basis
Because EEG is _______ in nature, the activity varies in amplitude and phase
Oscillatory
What is phase coupling in EEG?
Scientists can measure if there is coupling of the peaks and troughs of the activity
What are ERPs?
Event-related potentials (ERP) are recorded in reference to a specific event
What are the two categories of components that ERPs are characterized by?
- Exogenous: in response to an external event
- Endogenous: in response to an internal event
what are ERP tables measured in?
Milliseconds after the event
Magnetoencephalography (MEG) is a type of scan that measures what?
Records magnetic potentials produced by brain activity
What are MEG scans most commonly used for?
- to localize the source of epileptic activity
- to locate primary sensory cortices during neurosurgical intervention
- to understand language, object recognition, and spatial processing among others
Advantages of MEG
- we wont get interference from factors such as the skull and scalp because the magnetic field is strong and does not vary
- the strength of the magnetic field outside of the head can give info about how deep within the brain the source is located
Disadvantages of MEG
- requires a special magnetically shielded room to shield against the earth’s magnetic field and from other sources of electromagnetic radiation
- it is expensive
What methods are used a lot on young children?
Optical recording methods
Ex: mirror infrared activity
What two ways are optical recording detectors sensing how the path of light is altered? What are their characteristics?
- By Asorption
- oxygenated and deoxygenated blood are separate
- response is associated with Hemodynamic changes on the order of seconds. Is the SLOW SIGNAL because of this
- By Scattering
- related to physiological characteristics such as swelling of glia and neurons associated with neural firing
- response is associated with neural firing. Is the FAST SIGNAL because of this
What two techniques are used for modulating brain activity?
- Transcranial magnetic stimulation (TMS)
- Transcranial Direct Current Stimulation (TDCS)
Difference between TMS and tDCS
TMS: pulses a magnetic field over the scalp to induce an electrical field and alter the membrane potential of neurons
TDCS: weak electrical current runs through the scalp, skull, and bran between and entrance and exit electrode
TDCS brain stimulation below the anodal and cathode
Stimulated below anodal (positive) —> neuronal activity is increased (think anodal activates)
Stimulated below cathode (negative) —> neuronal activity is decreased
Compared to TMS, tDCS is…
- safer to use because stimulation is less intense
- less focused spatially
Formal models
Take a standard mathematical form
-these are falsifiable
Computational cognitive neuroscience
Involves building neural network models that model the actions of neurons in different brain networks
Where does the cell body of a motor neuron reside?
In the ventral part of the spinal cord
Typically how many motor neurons inner ages a number of muscle fibers?
One
Motor neurons only inner are ____-____ for muscles involved in fine motor control and over _____ for large muscles
2-3; 100
Motor unit = ____________ + ___________
Motor neuron + muscle fibers
What is involved in the lateral pathway?
- fine motor movements of distal limb muscles (ex: hands, fingers, lower leg, no foot)
-CONTRALATERAL control
What is involved in the medial pathway?
- control of movements of the trunk and proximal limb muscles
- posture and bilateral movements
- projects both CONTRALATERALLY and IPSILATERALLY
What does the Cerebellum play important roles in?
- coordination of muscle movement timing
- the planning of movements (and anticipating further muscle contractions)
- learning of motor skills
What are the three divisions of the cerebellum?
Vestibulocerebellum, Spinocerebellum, and Cerebrocerebellum
True or false: Cerebellar damage causes eradicate movements
False, they degrade motor capabilities instead
Where does the Vestibulocerebellum receive input from?
The vestibular nuclei in the brain stem
Why does the Vestibulocerebellum get constant feedback?
To maintain postural control
What does damage to the Vestibulocerebellum cause?
Difficulty with balance and to postural instability
What type of information and from where does the Spinocerebellum get information from?
It receives somatosensory and kinesthetic information from the spinal cord
What does damage to the Spinocerebellum do?
Causes difficulty with smooth control of movement, and the movement of proximal muscles (such as coordinating the trunk and leg muscles for walking)
Where and what type of info does the cerebrocerebellum get?
It receives input from many regions including both motor and association cortices
It gets info to regulate highly skilled movement that requires complex spatial and temporal sequences including sensorimotor learning
Which level of the cerebellum is the most high level area?
Cerebrocerebellum
Cerebellar ataxia
Difficulties in coordinating movement after Cerebellar damage
what is it called when there is a difficulty of speech output after Cerebellar damage?
Cerebellar dysarthria
What is the traditional test given to patients with suspected Cerebellar damage?
A test for the patient to touch their nose and then touch their finger to the neurologist’s finger
What is the tremor called in a patient with Cerebellar damage vs a patient with a resting tremor?
Cerebellar damage: Action or Intention tremor
Basal Ganglia: Resting tremor
What is Decomposition of Movement
Patients move one joint at a time in a serial manner
What type of learning is disrupted where the patient can’t learn to adjust an action in scenarios such as in eye-blink conditioning?
Sensory-motor learning
Predicting the sensory consequences of motor plans is often referred to as _______
A forward model
What does the basal ganglia consist of?
- Caudate nucleus
- putamen
- nucleus accumbens
- globes pallidus
- substantia nigra
- subthalamic nucleus
What are the 4 loops of the basal ganglia?
- A limbic (emotional) circuit
- An associative (cognitive) circuit
- A sensory circuit
- A motor circuit
What is the basal ganglia for?
The accomplishment of movements that may take some time to initiate or stop
What is the basal ganglia’s role in the motor system?
- “setting” the motor system with regard to posture
- preparing the nervous system to accomplish a voluntary motor act
- acting as an autopilot for well-learned sequential movements
- controlling the timing and switching between motor acts
True or False: because they receive both motor and non motor information, the basal ganglia are also thought to assist in motor planning and learning
True; goal directed movements!
Akinesia
The inability to initiate spontaneous movement
Bradykinesia
Slowness of movement
Tremors
Rhythmic, oscillating movements
A Parkinson’s patient is characterized by:
Akinesia, bradykinesia, and tremors
Which pathway is affected in Parkinson’s disease?
The direct (“GO”) pathway
What is the disrupted direct pathway in Parkinson’s due to?
Death of cell bodies in the substantia nigra -> inadequate input to the basal ganglia resulting in the indirect (“no go”) pathway becoming overactive
Huntington’s disease is characterized by:
Hyperkinesias (Chorea and Athetosis)
Hyperkinesias
Involuntary, undesired movements
Chorea
Uncontrollable, jerky movements such as twitching and abrupt jerking of the body
Athetosis
Involuntary writhing contractions and twisting of the body into abnormal postures
What does selective loss of striatal neurons that bund GABA do?
Affects the indirect pathway and reduces its function
Lateral and medial portions of the brain are involved in _______ control
Motor
Lateral regions of the cortex include
- the primary motor cortex
- the pre motor cortex
- the frontal eye fields (FEF’s)
- parietal cortex
The medial regions of the cortex include
- anterior cingulate cortex
- the supplementary motor complex (SMC)
Primary Motor Cortex
Thought to control the force and/or direction with which the motor plans are executes
What are the premotor region, supplementary motor cortex, and frontal eye fields involved in
specifying, preparing, and initiating movement
What is the Anterior Cingulate important for?
selecting among particular responses and monitoring whether the execution of those actions occurred appropriately
ex: Dr. worthy’s failed cartwheel
What are the parietal regions involved in?
linking movements to extrepersonal space and sensory information, as well as linking movements to meaning, as occurs in gesture
Which is the highest level cortical region?
The Anterior cingulate
Parietal is more of a ______ pathway while temporal is more of a _______ pathway
where; what
Primary Motor Cortex (M1)
provides the command signal to drive motor neurons to make muscles move
What does damage to the primary motor cortex cause?
the person cannot control the force with which muscles are exerted or, in severe cases, Hemiparesis
Hemiparesis
the inability to make motor movements on one side of the body
What determines the direction of movement?
summed activity across the population of neurons
The supplementary motor complex (SMC) comes up with what at the most abstract level?
motor plan
What are the three sub-regions of the supplementary motor complex (SMC)?
- pre-SMA
- supplementary frontal eye field (SEF)
- supplementary motor area (SMA)
SMC projects to both the ___________________ and the ________________ motor cortex, as well as the _________________ SMC
ipsilateral; contralateral; contralateral
What are the two distinct sub-regions of the premotor cortex?
Dorsal premotor area (PMd) and the Central premotor area (PMv)
Dorsal premotor area (PMd)
processes the motor significance of sensory cues, coding what type of motor action should be chosen or selected based on sensory information
Central Premotor area (PMv)
- involved in implementing these motor programs and adjusting them so hat objects can be manipulated
- contains mirror neurons
Anterior Cingulate Cortex (ACC)
aids in the planning and execution of movement
What are the three sub-regions of the ACC?
caudal region, middle region, and the anterior region
Caudal Region of the ACC
connects mainly to the primary motor cortex and the parietal lobe
- may modulate or override activity during simple motor tasks
Middle region of the ACC
connects primarily to the premotor cortex
- may modulate the selection of movements
Anterior region of the ACC
connects primarily to dorsolateral prefrontal cortex
- may modulate more complex motor actions or become active when a high degree of conflict exists
right inferior frontal cortex
plays a role in interrupting or inhibiting motor actions and is often assessed via the stop-signal paradigm
Greater damage of the right inferior frontal cortex is associated with more difficulty to what?
do the stop signal task
some scientists argue that the right inferior frontal lobe plays a role in _______ _________ based on the current environmental context rather than inhibiting actions
altering actions
Parietal regions are sensitive to what two kinds of information?
proprioceptive and kinesthetic
Damage to superior regions of the parietal lobe leads to what?
an inability to guide limbs in a well-controlled manner, and is often accompanied by a tendency to misreach
Damage to the inferior regions of the parietal lobe leads to what?
apraxia (when a person is unable to perform a task or movement when asked to do so)
What are the 4 major symptoms of Parkinson’s Disease?
- tremors
- cogwheel rigidity
- akinesia/bradykinesia
- disturbances of posture
What is Dystonia in Huntington’s disease?
slower movements caused by increased muscle tone and contractions that lead to abnormal posture such as tilting of the head or arching of the back
What is Huntington’s disease caused by?
an autosomal dominant gene
(when the gene is inherited, it always expresses itself)
How many tics per minute do people with Tourette’s syndrome experience?
30-100
Apraxia
the inability to perform Skilled, purposeful movement
Ideational apraxia
impaired ability to form an idea of intended movement
ideomotor apraxia
disconnection between the idea of the movement and its execution
What are the different ways that people categorize apraxia?
- descriptive grounds
- referencing the body part that is affected
Praxis
conception, planning, and production of skilled movement
Constructional apraxia
items cannot be correctly manipulated with regard to their spatial relations
Callosal apraxia
a disconnection syndrome that is characterized by an inability to perform a skilled motor act with the left hand in response ot a verbal command
What is Callosal apraxia due to?
a lesion of the callosum
What is retinal tissue derived from?
neural tissue
What are the two main types of ganglion cells?
M cells and P cells
M cells
are responsive to coarse pattern and detect rapid motion
P cells
preserve color information
Tectopulvinar Pathway
allows people to orient quickly to important visual information- motor detection
-involves the superior colliculus (part of the tectum) and the pulvinar nucleus of the thalamus
Geniculostriate Pathwayy
enables perception of color and detail
- Axons terminate in the lateral geniculate nucleus
Is the tectopulvinar pathway slow or fast acting?
Very fast-acting!
What type of ganglion cell does the tectopulvinar pathway receive input from?
M cells
(M for magnocellular)
what is the site of integration of the auditory and the visual senses?
the superior colliculus
what are the layers of the lateral geniculate nucleus called?
K-cell layers
