Ch 1-5 Outline - Chapter 2 Cognitive Neuroscience I Neurons...

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Chapter 2: Cognitive Neuroscience I. Neurons: The Building Blocks of the Nervous System A. The Micro-structure of the Brain: Neurons Camillo Golgi developed the Golgi stain that stains fewer than 1% of the cells. Ramon y Cajal used the stains to observe some of the cells in a slice of brain tissue. He then studied tissue from the brains of newborn animals because the density of the cells are smaller. Cajal's discovered that neurons were the basic building blocks of the brain Neuron Doctrine : the idea that individual cells transmit signals in the nervous system and that these cells are not continuous with other cells as proposed by the nerve net theory. Cell body contains mechanisms to keep the cell alive. Dendrites branch out to receive signals from other neurons. Axon or nerve fibers transmits the signals and the synapse is the gap between the end of the axon and the dendrites of another neuron. Myelin is the insulating coat on many axons that helps the neuron to send signals faster. Cerebral Hemispheres are the two halves of the brain Visual Hemispheres are the halves of space that are represented in each visual cortex B. The Signals that Travel in Neurons Edgar Adrian won the Nobel Prize being able to record the electrical signals from single sensory neurons using microelectrodes which are small shafts of hollow glass filled with a conductive salt solution that can pick up electrical signals at the electrode tip. The recording electrode is positioned near a neuron and the reference electrode is located outside of the tissue. The difference in charge between the recording and reference electrodes is shown on an oscilloscope. When no electrical signals are being transmitted, it is at -70mv. When an action potential or nerve impulse travels down the axon, it causes a brief pulse which appears as a “spike” on an expanded time scale. Increasing stimulus intensity causes an increase in the rate of nerve firing. When the signals reach the end of the axon from the dendrite, a chemical called a neurotransmitter is released that makes it possible for the signal to be transmitted across the synaptic gap. Adrian also discovered that the intensity of a stimulus can be represented by the rate of nerve firing. II. Localization of Function It is the principle that says specific functions are served by specific areas of the brain. The cerebral cortex is where most of the cognitive functions are served by. It is a wrinkled layer of tissue about 3 mm thick that covers the brain A. Localization for Perception Temporal lobe is the auditory receiving area. The primary receiving area for vision occupies most of the occipital lobe and the area for the skin senses—touch, temperature and pain-- is located in the parietal. The
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Ch 1-5 Outline - Chapter 2 Cognitive Neuroscience I Neurons...

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