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Sensing, responding & learning
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- 1What are the two ways that behaviours can be initiated?1) Internally-initiated (act of will)
2) Stimulus-elicited (involuntary) - 2Define stimulus-elicited behaviourBehaviour produced as an involuntary and relatively immediate consequence of sensory stimulation (behaviour is a reaction/response to stimulus)
- 3What distinguishes reflexes from other types of stimulus-elicited behaviour?In a reflex, the eliciting stimulus is proximal
Other stimulus-elicited behaviour e.g. modal action pattern requires identification/recognition of a distal stimulus/properties - 4What is proximal stimulation?Physical energy or force that impinges on sensory receptors and causes a change in them
i.e. energy to which the sensory receptors respond (e.g. light/sound) - 5What is distal stimulation?Sources/causes of proximal stimulation
Something in the environment that is perceived - 6Give an example of a modal action patternEgg-retrieval behaviour
Nesting bird perceives an 'egg' outside of nest (closeby) it will retrieve it
Identifies 'egg', not simply responding to proximal stimulation - 7What are the two ways stimuli elicit responses?1) Releasing mode of elicitation
2) Driving mode of elicitation - 8Define stimulus driven response Give an exampleNeural activity evoked in sensory neurons by the eliciting stimulus drives the muscle contractions/gland activity
E.g. pupillary reflex - 9Define stimulus released response Give an exampleActivity is derived from response production circuitry that generates signals when activated by stimulus
Response =independent of stimulus strength
E.g. egg retrieval - 10What are the characteristics of a stimulus driven response?1) Duration - depends on stimulus duration
2) Amplitude/vigour - strong stimulus = larger reaction etc
3) Variation - follow variation in stimulus strength - 11Give an example of when a releasing mode of elicitation is appropriateWhen the size of the response needs to be independent of stimulus strength
E.g. orienting reflex - want the turn to depend on location of stimulation, not strength - 12What is the reflex arc?A chain of neurons that link sensory receptors to motorneurons
- 13What does a skeletomotor reflex arc connect?Receptors to muscles that innervate skeletal muscles
- 14What are the 5 basic components of a reflex arc?1) Sensory receptor
2)Sensory neuron
3) Interneuron
4) Motor neuron
5) muscle - 15How many interneurons does a disynaptic arc have?One
(there are 2 interconnections between neurons) - 16What is an arc with more than two interneurons called?Polysynaptic arc
(monosynaptic=0 / disynaptic = 1 / trisynaptic = 2) - 17What is the only monosynaptic skeletomotor reflex?The phasic muscle stretch reflex
(aka monosynaptic stretch reflex) - 18What kind of reflex is the phasic stretch reflex?Spinal reflex - all neural cell bodies lie within spinal cord and body (brain is not involved)
- 19In a spinal reflex, the motorneuron cell bodies lie within the spinal cord and the sensory neuron cell bodies and axons lie within the body. What is another way to phrase this?Motorneuron cell bodies = central nervous system
Sensory neuron cell bodies & axons = peripheral nervous system - 20THe sensory neuron cell bodies are within the spaces formed by the vertebral notches. What is this space called?The dorsal root ganglia
- 21What is inside muscle spindles?Fibres called intrafusal muscle fibres
- 22What are the two types of sensory endings?Primary (Type 1a afferent) -- responsive to speed at which muscle is getting longer
Secondary (Type II afferent) -- responsive to amount muscle has been stretched - 23What is response strength measured by in a Type II afferent fibre?The rate of action potential propagation (firing rate: action per sec)
- 24In a Type II afferent fibre what is a strong stimulus?A large stretch
- 25Why are these receptors called slow adapting receptors?A sustained (constant) stimulus evokes a sustained response
- 26In a Type Ia afferent fibre, what is a weak stimulus?A slow stretch of the muscle
- 27Why are Type Ia receptors called fast adapting receptors?A stronger response is evoked by a stronger stimulus
When the length is not changing, there is little response - 28What type of spindle afferent is responsible for limb jerk reactions?Type Ia - tapping the tendon produces hardly any change in the length of the muscle
(usually less than thickness of a hair - too small to be detected)
However, very fast indeed = large response from Type Ia - 29Why is it a misconception to say that reflex responses are simple?Many autonomic reflex responses are simple (single stimulus produces single contraction in 1 or 2 muscles); most skeletomotor reflexes aren't
Involve many muscles (100+) activated in sequence - 30Why are most reflexes not stereotyped?They are adapted to the conditions of execution
E.g. wiping reflex in frogs (foot positioning depends upon stimulus location; movement depends on starting position) - 31What does the adaptability of the wiping reflex demonstrate?The frog's spinal cord 'knows' where the limbs are as well as where the stimulus is
- 32Which other skeletomotor reflexes have this goal-directedness?Scratching reflexes
Withdrawal reflexes - 33Are all reflexes spinal?No - any reflexes that involve a sensory organ in the head involve neurons in the brain
Any reflex that involves muscles in face/mouth involves neurons in the brain - 34How are horizontal movements of an eye produced?Contracting the medial and lateral recti
Medial rectus = moves left eye to the right (so inwards)
Lateral rectus = moves left eye to left (so outwards) - 35Where are the motor neurons that drive the extraocular muscles located?In nuclei within the brain stem
Medial recti motorneurons = within oculomotor nuclei at midbrain level
Lateral recti motorneurons = within abducens nuclei at pontine level - 36Signals from the left abducens nucleus and right oculomotor nucleus will move eyes to the...Left
- 37What are the two basic reasons for eye movements?1) to keep images on retina relatively still
2) to position images of things of interest onto foveas (most sensitive part of retina) - 38What is the vestibular-ocular reflex (VOR)?Reflex that keeps eyes steady enough to focus despite head jiggling; uses vestibular organs (part of inner ear)
- 39What happens if the vestibular organs are lost?Balance is quickly recovered (not as good but enough)
VOR is lost for good - permanently debilitating - 40What does the VOR do?Keeps eyes fixated on object of interest as head moves
Eyes counter-rotate so they remain pointing in the same direction
Operates in all 3 dimensions (horizontal, vertical & torsional) - 41Another type of eye movement is made in order to bring the image of an object of interest onto the foveas. What are these movements called?Saccades
Can be reflexive, voluntary or spontaneous - 42What type of saccade shifts the direction of gaze in both eyes the same way?Conjugate saccades
(disconjugate = opposite i.e. cross-eyed) - 43What muscles are involved in conjugate horizontal saccades?Medial and lateral recti
- 44To make a conjugate eye movement, these two nuclei have to be activated simultaneously. How is this done?Interneurons in the abducens nucleus connect to the contralateral oculomotor nucleus
- 45What else has to happen in addition to the contraction of these two muscles?Relaxation of the muscles on the other side
Achieved by inhibiting excitation of these muscles - 46What does the PPRF do?Region in the pons
Generates burst of excitation which causes eyes to move rapidly to new position (the saccade)
The 'command' signal - 47What stops the eyes from moving back to their original position?Another signal from the NPH
Sort of feedback loop
Turns burst from PPRF into continuous/sustained signal - 48How is the circuit activated (to produce saccades)?Pathways from sensory organs to the superior colliculi (midbrain nuclei) and then the PPRF
- 49What is the difference between a voluntary and a reflex saccade?Source of signal
Visual elicited reflex saccade = retinas
Voluntary = frontal cortex - 50Why does the VOR have to be turned off when you turn your head?Otherwise eyes would keep looking in same direction
Suppress with inhibitory
Often turn head as well as making voluntary saccade - 51How does the VOR response demonstrate that reflex responses are not inevitably repeatable?Whether they occur or not can be affected by intentions/mood/hunger etc
Intend to look in same direction = VOR
Diff direction = no VOR
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- Degree (Brain & Behaviour) Psychology Fichas sobre Sensing, responding & learning, creado por Rebecca Dunn el 14/05/2018.
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- Rebecca Dunn
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