NSCI 110 1st Edition Lecture 37 Outline of Last Lecture I Neural migrations begins at the subventricular zone and radiates outward to form layers of the cortex a Neuroblast soma follows path of radial glial cells b Growth cones aid advancement outward II Cell adhesion molecules provide a surface to which growth cones can attach a Tropic molecules are produced by target cells and increase axon affinity III Chemoaffinity hypothesis there are guidance cue gradients that attract axons to their targets a Increased tropic molecule concentration closest to the target cell IV Dendritic growth occurs at a slower rate than axonal growth V Apoptotic signals are induced by genetic mechanisms whereas synaptic pruning is induced by loss of functionality in a neural network a Loss of synapses and less dendritic arborizations b Cortex becomes thinner Outline of Current Lecture I Behaviors emerge as the adequate neural circuitry develops a Epigenetic factors affect the rate of behavioral development among individuals b Example grasping behaviors in infants II Language development is associated with increased dendritic complexity and increase myelination in speech areas of the brain III Jean Piaget proposed four primary stages of knowledge development a Sensorimotor b Preoperational c Concrete operational d Formal operational IV Stimulating environments promote maximum brain development a Individuals raised in enriched environments exhibit larger synapses and more astrocytes b Exercise dramatically increases neurogenesis Current Lecture Kallmann Syndrome neurons never migrate to the olfactory bulb o Results in anosmia sense of smell is not recoverable Hypogonadism low sex steroids o Individuals do not undergo puberty Behaviors don t emerge until the requisite neural machinery has developed o Develop through subsequent stages and are shaped by epigenetic factors These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o i e motor behaviors grasping in infants Right handedness arises around 10 months old o Axons of motor cortex are myelinated at the time that reaching and grasping develop o Gray matter thins with increasing pincer grasp ability Hand region of left motor cortex in right handers Language development o Language onset occurs at about 1 3 years of age is mostly complete by age 12 o Neural changes during this time Increased dendritic complexity and interconnections Increased myelination of speech areas Jean Piaget o Development psychologist interested in the process of developing knowledge o Stages Sensorimotor 0 2 stranger anxiety Preoperational 2 7 playing pretending beliefs symbolic representations Concrete operational 7 11 logic and conservation classification skills Formal operational stage 11 16 abstract thinking metacognition People raised in different environments cultures acquire differences in brain structure that effect behavior o Donald Hebb student of Lashley discovered that stimulating environments maximize intellectual development Compared with rats raised in standard lab cages those raised in enriched environments have larger and more synapses and astrocytes Evolutionary we need more stimulating and enriching environments o Hippocampus BrDU used to label new neurons Rats who exercised versus sedentary showed more neurogenesis Enrichment no exercise in either did not significantly improve neurogenesis Exercise has a more influential effect on neuronal growth
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