PSC140Lec4_6.24.10 - Brain and Sensory Development...

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Unformatted text preview: 6/23/10 Brain and Sensory Development Lecture 4 June 24th, 2010 PSC140 SSI The cerebral cortex The cerebral cortex   Occipital lobe   Processes primarily visual information   Temporal lobe   Processes primarily memory, visual recognition, emotion, and auditory information   Parietal lobe   Processes primarily spatial information and integrates sensory input with information in memory   Frontal lobe   Organizes behavior and executes planning 1 6/23/10 Cerebral [email protected] Right and left hemispheres of the cerebral cortex specialized for different kinds of processing   Corpus callosum     The dense tract of nerve Iibers that enable the two hemispheres to communicate   Lateralization begins early Brain development   The brain changes in terms of   Size   Dramatic increase in weight   Shape   Convolutions Iit more brain in the skull   Structure The neuron     A kind of cell specialized to be the units of the brain’s information system Cell body   Part of neuron that contains basic biological information that keeps the neuron functioning conducts it to cell body   Dendrites   Part of neuron that receives input from other cells and   Axon   Part of neuron that conducts electrical signals to connect with other neurons   Myelin sheath   Fatty cells that insulate axons and speed transmission of impulses from one neuron to the next 2 6/23/10 The neuron Brain development: Neurons   Neurogenesis   Proliferation of neurons through cell division   Migration   Neurons actively or passively relocate to destination   Growth and differentiation   Axons and dendrites grow and connect   Myelination   Increases speed of neural conduction [email protected] between neurons   Synapse   The gap between the axon of one neuron and the dendrite of another   Neurotransmitters   Chemicals that transmit signals between neurons   Serotonin   Dopamine   Epinephrine   Acetylcholine 3 6/23/10 [email protected] between neurons   Synaptogenesis   “Exuberant” generation of connections between neurons   Synaptic pruning   Elimination of under ­activated synapses   Plasticity   The brain’s capacity to be modiIied by experience Synaptogenesis Experience ­expectant processes How the brain wires is, in part, based on experiences that are species typical   If the expected experiences do not occur, development is compromised   Plasticity allows unused neurons to be recruited to other functions   Sensitive periods revisited   4 6/23/10 Experience ­dependent processes Neural connections are formed and organized according to an individual’s life experiences   This is the core of learning!   Plasticity allows neural growth to underpin and facilitate speciIic or expert actions   When the brain is damaged   Timing of damage is critical in degree of recovery   During adulthood – bad!   During very early development – bad!   Even during early childhood – not good Measuring the brain   Electroencephalographic (EEG)   Electrical activity of neurons   Event ­related potential (ERP)   Changes in electrical activity in response to a particular stimulus   Functional magnetic resonance imaging (fMRI)   Map of cerebral blood Ilow in response to particular stimulus via magnetic effect   Positron emission tomography (PET)   Map of brain activity via metabolism of radioactive agent 5 6/23/10 Brain development   During infancy there is major development of the   Visual cortex   Auditory cortex   Motor cortex Brain development   During childhood major development occurs   Frontal lobes   Attending   Organizing   Planning Brain development   During adolescence, a second wave of synapse production and brain reorganization occurs   The prefrontal cortex   Impulse control   Setting priorities   Identifying consequences   Pruning continues and the PFC does not become “adult ­like” until into the 20s 6 6/23/10 Sensory development   Sensation   Processing of information from the environment by the sense organs and brain   Perception   Organizing and interpreting sensory information Measuring infant vision   Visual preference paradigm   Showing infants two objects and noting if they prefer one over the other   Preference = looking longer   If infants show no preference, it is because they do not perceive a difference between the objects Measuring infant vision   Habituation paradigm   Habituating an infant to one object, presenting the infant with another object and noting whether the infant dishabituates to it     Infants look at object until bored (habituated) If infants perceive the second object as different from the Iirst, they will look longer (dishabituate) 7 6/23/10 Infant visual [email protected]   Visual acuity   The sharpness of visual discrimination Newborns have 20/300 to 20/600 vision   By 7 ­8 months, vision is adult ­like   Color perception intact   Infant visual [email protected]   Newborns scan and track, but not very well   2 ­month ­olds a lot more skilled   Infants have mastery of object segregation   Identifying separate objects in visual array Infant visual preferences Infants prefer patterns to solids, areas of high contrast   Faces are particularly interesting – more elements in the upper part of conIiguration   8 6/23/10 Infant depth [email protected]   Stereopsis   Perception of depth generated by the disparity between the input from each eye Appears at 4 months, with maturity of visual cortex   Pictorial cues     Monocular depth cues   Apparent at 6 or 7 months Infant depth [email protected]   Young infants perceive the depth change, but do not experience fear related to crossing a “cliff” Smell and taste Neonates clearly prefer smell of their own mothers over other women   Infants prefer sweet smells and tastes   9 6/23/10 Neonatal reflexes   Innate, Iixed patterns of action that occur in response to particular stimulation   Grasping   Rooting   Sucking   Swallowing   Tonic neck   Babinksi   Moro [email protected] senses together   Intermodal perception   Integrating information from two or more sensory systems Able to identify visually objects experienced through other senses   Prefer when the soundtrack matches the Iilm or the emotional tone of the voice matches the facial expression of emotion   10 ...
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This note was uploaded on 03/12/2011 for the course PSC 140 taught by Professor Lagatutta during the Summer '08 term at UC Davis.

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