Mt 1 Flashcards
L1 - What is the Degrees of Freedom Problem
There are infinite movements which end up with the same result/movement
L1 - Factors that influence RT
- Stimulus Intensity
- # of Choices
- S-R Compatibility
- Response Complexity
L1 - What is Hick’s Law
RT increases by a similar amount each time the number of alternatives is doubled
L1 - What is S-R Compatibility
Degree of natural or learned correspondence between a stimulus and a response
Ex. Congruent vs. Incongruent
L1 - Factors that Influence Movement
- Speed-accuracy trade-off
- End-State Comfort Effect
- Motor Equivalence
L1 - What are the stages of RT/movement task?
- Foreperiod
- Reaction Time
- Movement Time
L2 - What are two ways to study motor control
- Behavioural
- Neurophysiology
L2 - What is the 3 Stage Model in Information Processing
- Stimulus Identification - receives information from senses
- Response Selection - decides on a plan of action
- Response Programming - organize and prepare a response
L2 - What are the limits and benefits to Behavioural Study of Motor Control
Benefits
- Subjects can do complicated paradigms
- Need to validate tasks for future use
- Inexpensive
- Studying behaviour
Limits
- Potentially don’t get a full picture of why things are happening
-Only get a observed description, but not how things are happening neurophysiologically
L2 - What are the benefits and limitations of using Neurophysiology to study Motor Control?
Benefits
- Much more descriptive picture as to why and how the brain is processing the movements
- Can use brain activity to explain processing
- Can see where in the brain there is activity during these paradigms
Limits
- Can be potentially very expensive
- May not tell you exactly what you are looking for if using the wrong machine
- Can potentially be hard to get readings on brain activity if not done properly
L2 - Describe what an EEG is and how it works + pros and cons
-Movement of ions inside, across, and outside neural cell membranes creates electrical currents in excitable tissue
-Electrical currents travel to scalp surface
-Measure electrical potentials with electrodes placed on scalp
-TR: ms
-SR: cm
Pros
-Easy to record
-Cheap
Cons
-signals are smeared before they reach the scalp
-limited to activity in brain cortex surface
L2 - Describe what an MEG is and how it works + pros and cons
-Electrical neural currents create magnetic fields
-Measurement of magnetic fields of the brain
-TR: ms
-SR: cm
Pros
-Clean signals
Cons
-Expensive
-Insensitive to radial currents
L2 - Describe what an fMRI is and how it works + pros and cons
-Studied brain function
-Measures changes in blood oxygen levels
-It is closely related to changes in neural activity
-TR: sec
-SR: mm
-Knowledge gained: activated areas
Pros
-3D - volume resolution
Cons
-Expensive
-Low temporal resolution, no straight forward analysis
L2 - Describe what PET is and how it works + pros and cons
-Injection of a radioactive solution, in which atoms emit positively charged electrons (positrons)
-Positrons interact with electrons in the blood to produce photons of electromagnetic radiation
-Scanner used to determine the location (and levels) of these photons in brain areas
-TR : ms
Pros
-Cleanest signals
Cons
-Training
-Expensive
L2 - Describe what TMS is and how it works + pros and cons
-Coil placed over target brain region
-Cognitive failures recorded
-Focused oscillating magnetic fields can activate or suppress neural activity across the skull
Pros
-Non-invasive
-Allows direct manipulation of neural activity
-Single pulses affected brain activity for only a few seconds
-Repeated pulses can change brain activity for weeks
Cons
-Sensation can be disturbing
-Spread of activation/inhibition
L3 - List Function of Soma
-Contains nucleus, cytoplasm, organelles, metabolic center
L3 - List Function of Dendrites
-Receives information
L3 - List Function of Axon
-Transmits information (0.1 to 3 meters long)
L3 - List Function of Myelin Sheath
-Covers the axon to increase transmission speed
L3 - List Function of Presynaptic Terminal
-Communication site
L3 - What are the functional components of a Neuron
-An input component (dendrites)
-An integration component (axon hillock)
-A transmission component (axon)
-An output component (synapse)
L3 - What are the different types of neurons
-Sensory neuron
-Motor neuron
-Local interneuron
-Projection interneuron
-Neuroendocrine cell
L3 - What is a sensory neuron
-Transmit sensory information from sensory organs and receptors to the CNS
-Leads into CNS
L3 - What is a motor neuron
-Transmits motor impulses from the CNS to specific motor neurons
-Leads to muscles
L3 - What is a local interneuron
-Transmits signals between nearby neurons
-Helps integrate and process information in a localized area, facilitating communication between sensory and motor neurons
-Lead into other neurons in the same local region
L3 - What are projection interneurons
-Receive input from sensory neurons or other interneurons and transmit the information to distant targets within the CNS
-Are useful for longer distances
L3 - What portion of the spine has the most grey matter and why
-Sacral levels
-Less sensory fibres have joined the spinal cord therefore there is more grey matter
L3 - What is grey matter and white matter
-Grey matter is cell bodies
-White matter are axons
L3 - What side of the spine does sensory inflow enter the grey matter
-Dorsal horn (dorsal side)
L3 - What side of the spine does motor commands exit the spinal cord
-Ventral horn (ventral side)
L3 - How does the location of the neuron within the spinal cord relate to the muscle which is controlled
-Medial neurons in the grey matter deal with proximal muscles (shoulder & elbow) and axial muscles (trunk)
-Lateral neurons in the grey matter deal with distal muscles (wrists)
L3 - How does the segment of the spinal cord relate to where in the body the neurons will affect
-The higher in the spinal cord the neurons are, the higher the muscles are that are affected
L3 - What are the types of spinal cord neurons
Projection neurons
-ascend to the brain
Propriospinal neurons
-reach distant spinal segments
Motor neurons
-Exit the central nervous system to innervate muscles
Interneurons
-Project within their own adjacent spinal segments
L3 - What is membrane potential
Membrane potential: difference in net electrical charge on either side of the membrane
L3 - What is action potential
A short-lasting event in which the electrical membrane potential rapidly rises and falls
L3 - List and Describe Part A of Neuron firing
-The input signal is graded in amplitude and duration, proportional to the amplitude and duration of the stimulus
L3 - List and Describe Part B of Neuron firing
-The trigger zone integrates the input signal into a trigger action that produces action potentials that will be propagated along the axon. An action potential is generated only if the input signal is greater than a certain spike threshold. Once the input signal surpasses this threshold, any further increase in amplitude of the input signal increases the frequency with which the action potentials are generated, not their amplitude. The duration of the input signal determines the number of action potentials.
L3 - List and Describe Part C of Neuron firing
-Action potentials are all or none. Every action potential has a the same amplitude and duration. Since action potentials are conducted without fail along the full length of the axon to the synaptic terminals, the information in the signal is represented only by the frequency and number of spikes, not by the amplitude
L3 - List and Describe Part D of Neuron firing
-When the action potential reaches the synaptic terminal, the cells release a chemical neurotransmitter that serves as the output signal. The total number of action potentials in a given period of time determines exactly how much neurotransmitter will be released by the cell.
L3 - What diseases can change neuron firing and why
ALS/Lou Gehrig’s disease
-Degeneration of motor neurons
Multiple sclerosis
-Damage to myelin sheath
L3 - What are the 3 categories of movement
-Reflex
-Rhythmic
-Voluntary
L3 - List examples of reflex movements
-Coughing, blink, withdrawal, stretch reflex
L3 - List examples of rhythmic movements
-Chewing, breathing, locomotion
L3 - Explain what reflex movements are
- Stereotyped, fast-responding, involuntary
L3 - Explain what rhythmic movements are
-Driven by circuits in brain stem and spinal cord which can function autonomously but are influenced by higher centres
L3 - What does a sensory receptor (muscle spindle) do
-When muscle spindle is stretch, it increases firing rate of afferent neuron
-When slackened, decreases firing rate of afferent neuron
L3 - What is the order of monosynaptic reflex circuit
- Sensory signals
- Motor signals
- Muscle signals
L3 - What is the Hoffman reflex
L3 - Describe the Gain of System
High Gain
-Larger H reflex
Small Gain
-Smaller H reflex
L3 - What are the most common spinal cord injuries
Severing spinal cord
L3 - What are the 5 levels of SCI
A. Complete - No motor or sensory function is preserved in the sacral segments
B. Incomplete - Sensory but not motor function is preserved below the neurological level and includes the sacral segments
C. Incomplete - Motor function is preserves below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3
D. Incomplete - Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more
E. Normal - Motor and sensory function are normal
L4 - What is the function of the brain stem
-Concerned with sensation from and motor control of the head, neck and face
-Point of entry for several specialized senses (hearing, balance, taste)
-Mediate reflexes of autonomic nervous system (e.g. heart rate, digestion, respiratory rate, salivation, perspiration, pupillary, dilation, micturition, sexual arousal)
-Carries sensory and motor information to the other division
L4 - What is the Reticulospinal Pathway
-Individual axons project widely, coordinating different regions of the spinal cord
-In ventromedial cord, contact interneurons, long propriospinal cells, & some motor neurons
-Influence axial & proximal muscles
L4 - What are the divisions of the brain stem and what are their functions
- Medulla - Regulates blood pressure and respiration, receives input regarding taste, hearing and maintenance of balance & involved in control of neck and facial muscles
- Pons - Relays information about movement and sensation from the cerebral cortex to the cerebellum & involved in respiration, taste and sleep
- Midbrain - Forms linkage between parts of motor system (cerebellum, basal ganglia, and cerebral hemispheres)
L4 - What is premotor time & motor time
Premotor time
-“Central processing time” – information processing activity involved in preparation
Motor time
-Represents muscular processes - initial contractile activity required to overcome inertia
L4 - What is the tri-phasic muscle activation pattern
- First agonist burst (AG1)
-precedes movement onset
-burst amplitude and duration are dependent on movement amplitude
-burst amplitude reflects force - Antagonist burst (ANT)
-burst amplitude and timing influenced by movement extent and velocity
-early onsets with small, fast movements
-may represent braking - Second agonist burst (AG2)
-helps to “clamp” limb at target position
L4 - What is the process of startle leading to preplanned movements
-Startle activated midbrain reticular formation
-Movement program stored in midbrain reticular formation
-Program carried to appropriate muscles by reticulospinal tract
L5 - What makes up the Diencephalon
- Thalamus - integrates motor (and sensory) information
- Hypothalamus - homeostasis and reproduction
L5 - List the Direct Path of the Basal Ganglia to the Cortex
- striatum
- GPi (internal)
- thalamus
- cortex
L5 - List the Indirect Path of the Basal Ganglia to the Cortex
- striatum
- GPe (external)
- STN
- GPi
- thalamus
- cortex
L5 - What does the Basal Ganglia do?
-Selecting and maintaining purposeful motor activity while suppressing unwanted or useless movements
-Controls force production
-Fine tunes movements (like cerebellum)
-Involved in making movements smooth
-Autopilot for well-learned movements, timing and switching, planning , learning
-Helps monitor and coordinate slow, sustained contractions related to posture
L5 - Explain what the Direct path of the Basal Ganglia to the Cortex does
-Decrease inhibition of thalamus
-Leads to less inhibition of the thalamus, i.e. striatum inhibits GPi which in turn inhibits its normal (inhibitory) action on the thalamus, thus leading to greater excitation from the thalamus to the cortex
-Allows one to sustain actions or initiation of action