Chapter 4

Chapter 4Neural MechanismsContributions and Control

The Nervous SystemCentral Nervous System (CNS)Brain and spinal cordProcesses:Sensory information is integratedDecisions are madeSignals are generated and sent to muscles and glands to carry out responsesThe Nervous SystemPeripheral Nervous System (PNS)Nerves that extend from brain and spinal cord, linking body and CNSAfferent division: Detects changes in the environment and conducts nerve impulses from sensory receptors to CNSEfferent division: Transmits nerve impulses away from the CNSSensory ReceptorsExteroceptors:Detect stimuli outside the bodyProvide information about the external environmentInteroceptors:Detect stimuli from internal visceraProvide information about the internal environmentProprioceptors:Provide information regarding body position and movementDetect changes in muscle tension, joint position, and equilibriumVisionPredominant sensory receptor:70% of all the bodys sensory receptors are located in the eyes40% of the cerebral cortex is thought to be involved in some aspect of processing visual informationSport vision:Focuses on investigating visual contributions to performanceBasic Structures of the Eye

Visual Fields of the Eyesand Associated Neural Pathways

Focal vs. Ambient VisionFocal system:Functions to identify objects located primarily in the center of the visual fieldLinked to consciousnessOperates under voluntary controlAmbient system:Thought to be responsible for spatial localization and orientationFunctions at a subconscious levelServes both central and peripheral visual fields

Your PerspectiveWhen you are out walking or bike riding in the woods, what do you pay attention to and what other things are you just vaguely aware of?How does this differ when you are walking down a city street at night?Visual Abilities in PerformanceEye dominanceSpotting FixatingVisual searchEye DominanceOne eye processes information and transmits it to the brain more quickly than the otherSame-side dominantCross-dominant

Visual Search StrategiesQuiet eyeTargeting skills:Archery, rifle shooting, putting, free throws in basketball, etc.Interceptive skills:Striking, catching, landing, avoiding a collisionTactical skills:Quick, accurate situational decision makingAttention to relevant environmental cuesPattern recognition

VisionTips for PractitionersDevelop effective visual search strategies:Instruction and feedback should direct learners to areas where critical cues occurAppropriate learning experiences should provide extensive practice opportunitiesVideo trainingwith challenges to anticipate an opponents actionsContext of learning situations should include a good deal of variability

ProprioceptionThe continuous flow of sensory information received from receptors in muscles, tendons, joints, and inner ear regarding movement and body position.Types:Golgi tendon organsMuscle spindlesJoint kinesthetic receptorsVestibular apparatusProprioception and PerformanceMakes the motor control system more efficient and flexibleProvides information about initial body and limb position, which serves as the basis of programming of motor commandsEvaluates movement for correctness:Compares proprioceptive feedback to the intended goalMakes adjustments

Transmission of Information via the Spinal Cord

Sensory and Motor PathwaysSensory (ascending) pathways:Spinothalamic and posterior or dorsal column pathwayConduct impulses related to pain, temperature, touch, pressure, and vibrationsMotor (descending) pathways:Pyramidal and extrapyramidal pathwaysConduct impulses related to voluntary and subconscious movementsSpinal ReflexesAn automatic, involuntary response to stimuliReflex arcsimplest pathway by which a reflex occursTypes:Monosynaptic reflexPolysynaptic reflexReflexesMonosynaptic reflex loopWithdrawal and crossed extensor reflex arc

Damage to the Spinal CordTypes of injury:CompleteIncomplete: Effects depend on the area of the spinal cord affectedLevel of injury:In general, the higher up the spinal cord that injury occurs, the greater the extent of the injury.Parts of the BrainBrain stemDiencephalonCerebrumCerebellumAreas of the Cerebral CortexSensory areasMotor areasAssociation areasBasal gangliaFunctional Areas of the Cerebral Cortex

CerebellumMonitors movement by comparing what was intended with what is actually taking placePlays a key role in detecting and correcting errorsWorks with motor cortex to produce smooth, coordinated movementsPlays a key role in maintaining posture and balanceMemory Systems

Subsystems of Long-Term MemoryEpisodic memory:Information about personal experiences and eventsSemantic memory:General, factual knowledgeProcedural memory:Skills, operations, and actionsYour PerspectiveSometimes it is much easier to remember events from our childhood than to remember what we had for breakfast the day before yesterday. Why do you think that is?Why do you think certain smells or songs have such a strong effect on our ability to remember people and events?ForgettingDecay theoryInterference theory:Proactive interferenceRetroactive interferenceProactive and Retroactive Interference

MemoryTips for PractitionersKeep instructions and feedback short and simpleProvide ample opportunities for physical rehearsalRelate a skill being learned to previously learned skillsUse meaningful labels and analogies to strengthen associationsGroup several movements together