Psych 210 Exam 3 Touch Ch 11 somatosensory system relays information about the body o touch temperature body position proprioception organic senses heart burn pain nociception Labeled Line System receptors are neurons that transduce or change a physical stimulus into neural events o In the skin each receptor has a specialized ending that responds to a specific attribute of the stimulus o Labeled line different receptors for different qualities have different line to the brain Such as Ruffini s ending stretch Pacinian corpuscle vibration When deformed skin vibrate sodium channels are opened which depolarizes the endings if its depolarizes enough it creates an action potential Meisssner s corpuscle touch Merkel s disc touch Free nerve endings pain and temperature o Plays factor on receptive field exhibit adapting The region of the receptor surface that excites or inhibits a sensory neuron smallest in the fingertips larger in the hand larger in the arm The receptive fields size varies with use Adaption loss of sensitivity to continuous presence of stimulus o If you don t change pressure then your brain doesn t need to know Somatosensory pathways information ascends in the dorsal columns to the medulla then to thalamus and then to somatosensory cortex o information coming in through the bottom o Reaches medulla sensory information crosses over o Goes to thalamus then somatosensory cortex Dermatomes you have axons coming in your sacral region all the way up your spinal cord until medulla o If you were to cut off any part of the spinal cord you would sever all the way down from where you cut o Coccygeal sacral lumbar thoracic cervical No need for face muscles to go to spinal cord Somatosensory cortex is just posterior to the central sulcus o Plastic changing type of information to the brain after training Movement Ch 11 muscle receptors o Golgi tendons organs contraction o Muscle spindle receptors stretch Primary sensory endings innervate the central region of the muscle spindle Secondary sensory endings innervate the thin ends of the muscle spindle Sensory information enters spinal cord via dorsal root Motor information exits spinal cord via ventral root Muscle receive neural input from motor neurons in the spinal cord Motor neurons release acetylcholine ACh There is multiple sights of synaptic contact Cidocoline activates muscle Stretch reflex the position of the muscle is set by the brain the tap on the patella tendon creates an error and the error signal to try to return the limb to its original position o The activation pattern of spine and brain Babinski sign underdeveloped motor system Damage to motor cortex corticospinal track Baby doesn t have fully developed nervous system Major components of movement o Spinal cord o Cerebellum basic coordination of limbs eye movements balance muscle tone Flocculonodular lobe vestibular control Vernis and anterior lobe motor coordination limb control Posterior lobe initiation planning timing Damage Right arm was right on time to point target and back to his nose Left arm could not focus on target and difficulty pointing at his nose o Behavioral traits depends upon the region damaged Depends on the behavioral trait depend upon the region damaged o Three layers molecular layer top purkinje cell layer granular layer o Two inputs climbing fibers mossy finers One output Purkinje cell form large planar dendritic trees in molecular layer guides movements by inhibiting neurons cerebellum is fine tuning motor movements o in order for control over motor movement smooth o climbing fibers form many synaptic connections with 1 10 purkinje cells all way up to molecular level then wrap around purkinje cells as it wraps around it is making synapses o mossy fibers form synaptic contact with many granule cells if you stimulate one mossy fiber it stimulate handful of parallel o granule cells project into molecular layer and form parallel fibers parallel fibers long lateral projections form synaptic contacts with multiple purkinje cells 1 parallel fiber wouldn t activate Levels of motor control o Spinal cord o Cerebellum o Cerebral cortex primary secondary motor cortex Motor cortex three regions o Primary motor cortex encode force and direction Lesion cause weakness Recorded neuronal activity in primary motor cortex while monkeys make arm movements o Supplementary motor area planning movements Lesions result in loss of voluntary movements Recorded neuronal activity while monkey moves arm toward an object Doesn t respond until an activation signal knows when it can move o Premotor cortex planning and control of limb movements Basal ganglia consists of the caudate nucleus putamen globus pallidus subthalamic nucleus substantia nigra o Encodes the amplitude direction and initiation of movement Parkinson s Disease 1 of US population over the age of 65 o Caused by a loss of dopamine from the substantia nigra midbrain to the basal ganglia o Phenotypic traits Body tremors when at rest Muscle rigidity Bradykinesia slow movements and akinesia no movement Huntington s Chorea incidence of 5 10 100 000 o Phenotypic traits Sudden jerky involuntary movements chorea throughout your body Severe problems with balance and coordination Jerky rapid eye movements o An inherited condition caused by a single abnormal gene o Resulting in a degeneration of cells in the basal gaglia Declarative Memory p 481 516 Henry Gustav Molaison HM o When he was very young he fell and hit the back of his head Had seizures and got worse with age o Doctor said he would check which part of the brain was over acting Medial temporal lobe 2 3 hippocampus removed Amygdala removed Removed cortex around hippocampus Helped reduce seizure o After his surgery he had severe amnesia o Outcome hippocampus memory Amnesia memory loss o Retrograded Amnesia loss of memory for the past HM lfor about 10 years before surgery o Anterograde amnesia inability to form new memories HM for long term storage of new memories Hypothesis of memory process information comes in sensory buffers encoding short term storage consolidation working memory retrieval performance long term storage Loss of information can happen at any stage Multiple trace hypothesis of memory o Sensory memory large capacity 1 2 seconds o Short term memory small capacity 5 9 times 15 18 seconds with rehearsal o Long term memory unlimited capacity lasts indefinitely HM unable to preform LT Mirror tracing task only way to see object hand is through mirror o HM