EXSS 380 Notes PDF

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Lecture notes were taken in Feb. of Spring Semester...

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EXSS 380 Notes Information Processing 

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Sensory information must be processed by the CNS o What info is provided?  Sensory information from receptors  Somatosensory cortex receives millions of action potentials a second. o How should the CNS respond?  Somatosensory association area: associates incoming sensory info with previous motor history  Communicates with motor areas of the brain, relates to past sensory experiences in the brain, determines the correct plan based on past memory in the motor are  Primary motor area receives signal, sends info to other brain parts, and down to neurons, and down into motor area and into muscles CNS analogous to a computer o Sensory input periphery processed and used to generate appropriate motor output Temporal analysis of what happens to sensory information as it passes through CNS o CNS considered a “black box” phenomenon  Things go on inside the box, but you don’t know what (bc you cannot see it)  Nature of internal processes inferred o Primarily focused on reaction time  Temporal delay b/w presentation of stimulus and response initiation  How long does it take the CNS to recognize, interpret, and respond to a stimulus  Reaction Time: is the temporal delay between when a stimulus is sensed and when a response is initiated. Stages of Information Processing o Three Stages  Stimulus identification (What is it? What does it mean?)  Stimulus must be recognized  Response selection  Which response (or lack thereof) is appropriate?  Response initiation/programming  Neurotransmitter system must be “primed”, the motor response initiated o Example: Approaching a traffic light  Stimulus identification: recognition of change in light color and significance  Response selection: stop or go? Influence by numerous factors (Current speed, closeness of trailing car, quality of brakes)  Response Programming: activate lower extremity musculature to press either the break or the gas

Taking your foot off the gas and to the break is a very complicated process in the neural portion of the brain. It is a very rapid process, but involves a large part of the nervous system so it is complex, even though it seems simple to us. Evidence of Information Processing o Donder’s Subtractive Method  Three tasks of increasing complexity  Increasing RT with greater movement complexity (more stage of processing)  Stages of Processing o Stimulus Detection o Response Execution o Simple Reaction Time  Visual stimulus and simple reaction task  Press a key with right index finger following light stimulus o Go/No-go Reaction Time  2 light stimuli: red= “go”, blue= “no-go” o Choice Reaction Time  2 Light stimuli: red= “right”, blue= “left” Stimulus Identification o Involves 2 substages  Stimulus detection  Sensory organs must detect and transmit information  Pattern Recognition  Most movement tasks associated with multiple stimulus  Inter-related stimuli typically presented in a prescribed pattern Response Selection Stage o Determination of the appropriate response is influence by sensory information o The time required to select the appropriate response is dependent on:  Number of stimulus-response alternative  Stimulus-response compatibility Response-Programming Stage o Final Stage of information processing  Cannot be initiated until the stimulus is identified and the appropriate response is selected  Appropriate response entails specified set of muscle activation designed for task completion  Most voluntary process are complex in nature and are retrieved from motor memory  Feedforward in nature o Motor programs o Classical experiment conducted by Henry and Rogers (1960)  “godfather of motor control study”  Basis for motor programming history  3 separate tasks following stimulus presentation o

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Lift finger of electronic key Lift finger of electronic key and grasp suspended tennis ball Lift finger of key, strike suspended tennis ball, press another electronic key, strike another ball o For all conditions, the stimulus was the same, and subjects were informed of the appropriate response (ie no response selection range) o Only the complexity of the movement differed o They found that as the complexity increased the reaction time also increased Components of Memory o Long-term memory: sensory information and motor plans transferred to long-term storage via rehearsal, or practice o Short-term sensory store (STSS)  Capacity to store massive amounts of sensory information for brief periods of time  Somatosensory, auditory, and visual stimuli, etc. o Short-term memory  Often referred to as “working memory”  Buffer area for STSS and long-term memory  Information from STSS and long-term memory integrated  Limited capacity and short duration  Response selection stage of information processing  Sensory information in short-term memory integrated with information from long-term memory (eg. Stored motor programs) during response selection stage Reflexive Neuromuscular Control o Joint perturbation  Joint maintained at a given position  Change in position=error  Load on join increased suddenly  Muscle response and kinematics recorded simultaneously o Feedback Control method Medium-and-long latency stretch reflexes o Polysnpatic o Longer duration o Greater amplitude o “Functional stretch reflex” Long latency stretch reflex o Ia afferent synpases with: homonymous a-mn, higher integrative centers via spinal tracts o Integrated with additional sensory info to provide more effective response  Greater latency due to required processing time  Shorter latency trade off from more effective response Situation-specific alteration of reflex responses   

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o H-reflex= electrical analog to spinal stretch reflex o Amplitude attenuated via changes in posture status and please of gait. Triggered Reactions o Stereotyped, coordinated neuromuscular responses o Typically involve multiple muscles or muscle groups o Latencies between 80-200 ms o “fast RT” potentially bypassing some stages of information processing  Stereotyped, predictable, well-practiced o Thought to be goal-oriented, rather than maintaining a peripheral characteristic...