Final Flashcards
Central Pattern Generators
Spinal (cranial) or motor circuits that control rhythmic behaviors
Feedback Inhibition
Flexors may excite extensors, which in turn inhibit the flexors to shut them off, depriving the extensors of their own excitatory input
-This simple feedback inhibition circuit can generate motor rhythms
Where is the primary motor cortex?
Most caudal part of the frontal cortex, just rostral to central sulcus
Stroke when a blood vessel is blocked by an embolism or blood clot, starving the brain of oxygen and glucose. If patient survives the stroke, only parital recovery
Ischemia
Caused when blood vessel bursts and bleeds into the brain, causing inflammation but not as much neuronal death. Higher risk of death during the stroke, but better recovery of function if the patient survives.
Hemmorage
What kind of memory problem did patient H.M have? What were the symptoms?
Total antero-grade amnesia for all declarative facts learned post-surgery
temporally-graded retrograde amnesia - better memory for “declarative” information acquired long before
surgery than recently before surgery
What kind of memory was normal in H.M and how was that tested?
Procedural memory and motor tasks were normal. H.M was able to improve at a memory task
What part of H.M.’s brain was removed and why?
Medial temporal lobe removed to treat severe epilepsy
What are the two kinds of declarative memory?
semantic memory (generalized memory for facts and info) Episodic memory - detailed autobiographical memory of event sequences from past
What are the three types of nondeclarative (procedural) memory?
Skill learning—learning to perform a task requiring motor coordination (example: eyeblinkconditioning). • Priming—repetition priming—a change in stimulus processing due to prior exposure to the stimulus. • Conditioning—the association of two stimuli or of a stimulus and a response (examples: eyeblink conditioning, fear conditioning, operant conditioning, etc.).
How does the delayed non-match-to-sample task work?
Monkey is presented with two objects, food is hidden under one after the monkey finds the food, a short delay occurs, then the monkey gets the two objects again but this time the food is hidden under the other object.
How do monkeys perform at the non-match-to sample task and how do brain lesions impact their performance?
- Normal monkeys are very good at the task
- Hippocampus lesions impair performance after long delays
- Prefrontal cortex lesions impair performance after short delays
Other than the hippocampus what other brain region lesions impair performance?
entorhinal cortex, parahimpocampal cortex, perirhinal cortex
How do hippocampal lesions affect contextual fear condition vs. tonal fear conditioning?
hippocampal lesions reduces contextual fear conditioning but not tonal fear conditioning
Do hippocampal lesions impair recent or distant memories? Is it different for rats and humans?
Hippocampal lesions impair recent but not distant memories in both rats and humans
Is the rat hippocampus proportionally smaller or larger than the human hippocampus and why?
Proportionally larger because rats have a much smaller cerebral cortex
What are the three major subdivisions of the hippocampus and what do they do?
- The dentate gyrus is involved in pattern separation
- The cornus ammonu3 is involved in pattern completion (filling in missing information in a pattern to facilitate later recognition)
- Cornus ammonu1 - main output circuit of the hippocampus
What are the parts, pathways and order of the tri-synaptic loop circuit?
Medial Entorhinal cortex — performant path —> dentate granule cells —Mossy fibers—> CA3 pyramidal cells —-Shaefer collaterals —-> CA1 pyramidal cells -> subiculum pyramidal cells —-> Medial entorhinal cortex
What kind of neurons become active when an organism needs to be motivated to spend energy and act?
Mesolimbocorticaldopamine neurons in the VTA
When an actual outcome was better than expected outcome
Positive prediction error
When an actual outcome was worse than expected outcome
Negative prediction error
When an animal learns which action will ultimately produce pleasure. (Action-outcome associations)
Instrumental learning
A signal that an action will produce an outcome
Discriminative stimulus (DS)
Cue that something negative or positive is about to happen
Conditional stimulus (CS)
How to rewards affect dopamine neuron responses in trained and untrained animals?
- In untrained animals, dopamine neuron increases firing rate when reward occurs (unexpected)
- In trained animals, the dopamine neuron increases firing rate during conditional stimulus (cue) but not during actual reward delivery
- During omission trial, dopamine neuron decreases firing rate below baseline if the reward does not appear when its expected
What was the result of the dopamine, food study?
After VTA lessioning, Rats were less likely to push a lever multiple times to get food but not less likely to push it once. This provides evidence for the incentive theory of dopamine release
What are the three non-mutually exclusive theories of dopamine as related to motivation?
- Reward Theory
- Prediction-error theory
- Incentive theory
A trained rat continuing to press a lever for food even after it has been adequately fed is an example of what type of learning?
Stimulus-action association or habit learning
What brain regions are involved in the goal-directed system?
-Prefrontal cortex
-Orbitofrontal cortex
-Hippocampus
-Nucleus Accumbens (ventral striatum)
Dorsolateral striatum
Term for an animal predicting what would happen if it followed a particular path
Model-based planning
How does long-term potentiation strengthen a synapse and what chemical pathway does it use to do that?
Greater concentrations of calcium trigger a chemical response that activates a glutamate receptor creating gene. When the cell fires and than receives glutamate it triggers the creation of AMP glutamate receptors
What types of cells have been discovered the entorhinal cortex and what do they do?
Grid cells in the entorhinal cortex fire like nodes of a hexagonal grid
-Border cells fire when the rat is approaching a barrier such as a wall in its cognitive map
what are place cells, when do they fire, where are they located in the brain and what is their firing rate?
- spatially tuned neurons in CA1 & CA3
- cell fires when the rat visits a preferred location, called the cell’s place field
- What rhythm to place cells fire at (8 Hz)
How has long-term potentiation been tested in a vat?
At baseline (PRE), each stimulus
pulse produces a small EPSP in CA1. After a strong highfrequency stimulus (HFS; 100 Hz train of electrical pulses), each
stimulus pulse produces a much larger EPSP in CA1 (POST)
How has long-term depresssion been tested in a vat?
At baseline (PRE), each stimulus
pulse produces a small EPSP in CA1. After a weak low
frequency stimulus (LFS; 1 Hz train of electrical pulses), each
stimulus pulse produces an even smaller EPSP in CA1 (POST)
How does long-term potentiation use neural coincidence detectors?
-At rest NMDA glutamate receptors have a Mg2+
that blocks the influx of cations to the intracellular
space
-Depolarization of the cell membrane removes the
Mg2+
-If the presynaptic cell releases glutamate during
depolarization, the NMDA receptor creates a
influx of calcium to the inside of the cell
How were place cells tested with rats in water?
In the Morris water maze, rats are placed in water and must find a hidden platform. When removed and then replaced in the water rats take less time to find the platform
What happens to place cells when the environment that rat has already explored changes?
The place cells change their firing pattern to reflect changes in the environment
-Different place cells change based on different contextual clues (e.g. olfactory vs. visual)
How does the brain consolidate information recorded in the recent past?
- When the rat is asleep or not-moving in the maze, place cells in the hippocampus fire in the same sequence as they did when recording a new memory but much faster
- Sometimes the order is faster and sometimes it is slower
What is one hypothesis why dream time seems to occur faster than real time?
The brain replays experiences faster (the actual sequence of cell firing is faster) when it is not constrained by motor realities in sleep
How are cells in the hippocampus organized?
They are not topographically organized and the centers are randomly distributed throughout the cognitive map
What kind of memory does the morris water maze test?
Declarative memory
Steps of the trisynaptic pathway?
Entorhinal cortex -> dentate gyrus -> CA3 -> CA1
How many bones are in the human body?
206
What controls skeletal movements?
skeletal muscle
Each muscle is a large bundle of many smaller ______
muscle fibers
_____ connect muscle and bone
tendons
Many skeletal joints are controlled by a pair of two _____ _________
antagonistic muscles
__________: contraction bends the joint (example: ____)
flexors, bicep
_______ :contraction straightens the joint (example: ______)
extensors, tricep
Muscles exert force by _______ (shortening of the fibers); they can only ____ a limb, not ____ it!
force by contracting
call only PULL a limb not Push
Running through the center of the muscle fiber is a bundle of protein filaments called a ________
myofibril
What are the two kinds of protein that compose a muscle fiber and what do they do?
- Actin: A cytoskeletal protein
- Myosin: A motor protein that grabs actin and “walks” along the actin filament
Each muscle fiber is a single large cell with many ______
nuclei
The muscle fiber is divided into segments called __________
sarcomeres
Myosin heads can shorten the sarcomeres by ___________________________________
grabbing actin filaments and drawing them together
A _______ is a single motor neuron plus all of the muscle fibers that it contracts
motor unit
Each motoneuron contacts ______, but each muscle fiber receives input from ______ motoneuron
multiple motorfibers that each receive input from only one motoneuron
Motor neurons in the spinal cord send their axons to muscle fibers, where they make synapses called ________
neuromuscular junctions
When the motor neuron fires an action potential, ______ is released at the NMJ
Acetylcholine
ACh binds to________ on the muscle fiber, causing ____ to enter
nicotrinic receptors; causing Na+ to enter
When Na+ channels open on the muscle fiber it does which three things:
- Opens calcium channels
- Fires an action potential
- Ca2+ enters the fiber, and this causes myosin to pull actin filaments together
Motor neurons are the __________ through which the brain and spinal cord control muscles.
final common pathway
Motor neurons release only ___ but they respond to a tremendous variety of synaptic transmitters, both ___________, released by the diverse inputs that each motor neuron receives.
Ach, excitatory and inhibitory
_______ carry motor commands from brain to body
ventral roots
How many pairs of nerves emanate from the spinal cord?
31
Motoneurons reside where?
Gray matter of the ventral horn of the spinal cord
Motor axons exit the ______ through the_______ to contact muscles in the head and face
brainstem; cranial nerves
What are the three primary sources of input to motoneurons and what do they do?
- The pyramidal motor system provides motoneuron inputs that initiate and control voluntary movements.
- The extrapyramidal motor system modulates motoneurons by fine tuning movements
- Sensory and proprioceptive neurons in the dorsal root ganglion provide motoneuron inputs (via interneurons in the dorsal horn) that mediate simple motor reflexes and central pattern generation.
The ________ is an automatic (involuntary) response to a painful stimulus
spinal withdrawal reflex
The withdrawal reflex can involve as few as ____ synapses
3
Central Pattern Generators
- motor circuits that control rhythmic behaviors
- receives tonic input from motor cortex, and converts it into phasic output to the muscles
- Sensory & proprioceptive feedback help to pace and control the motor rhythm
What sensory or motor singlas are lost when the right or left side of the spine is transected?
Motor: Loss of all motor function ipsilateral to the injury; contralateral function is spared
Sensory: Loss of contralateral nociception, ipsilateral proprioception and discriminative touch
When back half of spine is transected
Motor: Bilateral loss of voluntary motor function; olivospinal and vestibulospinal lpathways are spared, but don’t have much to do anymore
Sensory: Bilateral loss of proprioception& discriminative touch, no loss of nociception