Sensation - Cognitive Neuroscience Flashcards
Levels of analysis
Levels of analysis
A topic can be understood by studying it at a number of different levels of a system.
Neuron
Cell that is specialized to receive and transmit information in the nervous system.
Nerve net
A network of continuously interconnected nerve fibers (as contrasted with neural networks, in which fibers are connected by synapses).
Neuron doctrine
The idea that individual cells called neurons transmit signals in the nervous system, and that these cells are not continuous with other cells as proposed by nerve net theory.
Cell body
Part of a cell that contains mechanisms that keep the cell alive. In some neurons, the cell body and the dendrites associated with it receive information from other neurons.
Dendrites
Structures that branch out from the cell body to receive electrical signals from other neurons.
Axons
Part of the neuron that transmits signals from the cell body to the synapse at the end of the axon. (Also called nerve fibers).
Synapse
Space between the end of an axon and the cell body or dendrite of the next axon.
Neural circuits
Group of interconnected neurons that are responsible for neural processing.
Receptors
Specialized neural structures that respond to environmental stimuli such as light, mechanical stimulation, or chemical stimuli.
Camillo Golgi
An Italian anatomist that in the 1870s who developed a staining technique in which a thin slice of brain tissue was immersed in a solution of silver nitrate. Fewer than 1 percent of the cells were stained, so they stood out from the rest of the tissue. Also, the cells that were stained were stained completely, so it was possible to see their structure.
Ramon y Cajal
Spanish physiologist that used the Golgi stain, which stained only some of the cells in a slice of brain tissue. Second, he decided to study tissue from the brains of newborn animals, because the density of cells in the newborn brain is small compared with the density in the adult brain. This made it possible for Cajal to clearly see that the nerve net was not continuous but was instead made up of individual units connected together.
Won Nobel prize in 1906 for the understanding of how neurons function.
Edgar Adrian
In the 1920s, Edgar Adrian was able to record electrical signals from single sensory neurons, an achievement for which he was awarded the Nobel Prize in 1932.
Adrian drew a connection between nerve firing and experience. He describes this connection in his book The Basis of Sensation (1928) by stating that if nerve impulses “are crowded closely together the sensation is intense, if they are separated by long intervals the sensation is correspondingly feeble”
Microelectrodes
Small wires that are used to record electrical signals from single neurons.
Recording electrode
When used to study neural functioning, a very thin glass or metal probe that can pick up electrical signals from single neurons.
Reference electrode
Used in conjunction with a recording electrode to measure the difference in charge between the two. Reference electrodes are generally placed where the electrical signal remains constant, so any change in charge between the recording and reference electrodes reflects events happening near the tip of the recording electrode.
Resting potential
Difference in charge between the inside and outside of a nerve fiber when the fiber is at rest (no other electrical signals are present). The inside of the neuron has a charge that is 70 mV more negative than the outside, and this difference continues as long as the neuron is at rest.
Nerve impulse
An electrical response that is propagated down the length of an axon (nerve fiber) the charge inside the axon rises to +40 millivolts, compared to the outside. This impulse, which is called the action potential, lasts about 1 millisecond.
Neurotransmitter
Chemical that is released at the synapse in response to incoming action potentials.
Principle of neural representation
Everything a person experiences is based on representations in the person’s nervous system.
Feature detectors
Neurons that respond to specific visual features, such as orientation, size, or the more complex features that make up environmental stimuli.
Experience-dependent plasticity
A mechanism that causes an organism’s neurons to develop so they respond best to the type of stimulation to which the organism has been exposed.
Visual cortex
Area in the occipital lobe that receives signals from the eyes.
David Hubel and Thorsten Wiesel
In the 1960s conducted studies that demonstrated neurons respond to specific qualities. They won a Nobel prize in 1981.
They presented visual stimuli to cats and determined which stimuli caused specific neurons to fire. They found that each neuron in the visual area of the cortex responded to a specific type of stimulation presented to a small area of the retina.
Colin Blakemore and Graham Cooper
Demonstrated experience-dependent plasticity.
In 1970 reared kittens in a space in which they saw only vertical black and white stripes on the walls. After being reared in this vertical environment, kittens responded to moving vertical stick but ignored horizontal objects. Recording from neurons in the kittens’ brains revealed that the visual cortex had been reshaped so it contained neurons that responded mainly to verticals and had no neurons that responded to horizontals.
Temporal lobe
The lobe on the side of the brain that contains mechanisms responsible for language, memory, hearing, and vision.
Auditory cortex in upper region.
