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.
Hierarchical processing
Processing that occurs in a progression from lower to higher areas of the brain.
Charles Gross
Conducted an experiment (1969 and 1972) where neurons in the temporal lobe of monkeys were monitored when presented with more complex stimuli such as hands and faces. Neurons in different parts of the lobe would only respond to hands and others only to faces.
Demonstrates hierarchical processing in which signals from visual cortex are then sent for higher processing in certain areas of the temporal lobe.
Sensory code
How neural firing represents various characteristics of the environment.
Specificity coding
The representation of a specific stimulus by the firing of neurons that respond only to that stimulus. An example would be the signaling of a person’s face by the firing of a neuron that responds only to that person’s face.
Population coding
Neural representation of a stimulus by the pattern of firing of a large number of neurons.
Sparse coding
Neural coding based on the pattern of activity in small groups of neurons.
Localisation of function
Location of specific functions in specific areas of the brain. For example, areas have been identified that are specialized to process information involved in the perception of movement, form, speech, and different aspects of memory.
Cerebral cortex
The 3-mm-thick outer layer of the brain that contains the mechanisms responsible for higher mental functions such as perception, language, thinking, and problem solving.
Cortical equipotentiality
The idea, popular in the early 1800s, that the brain operates as an indivisible whole, as opposed to operating based on specialized areas.
Broca’s area
(1861) An area in the frontal lobe associated with the production of language. Damage to this area causes Broca’s aphasia.
Wernicke’s area
(1879) Area in the temporal lobe associated with understanding language. Damage to this area causes Wernicke’s aphasia.
Broca’s aphasia
A condition associated with damage to Broca’s area, in the frontal lobe, characterized by labored ungrammatical speech and difficulty in understanding some types of sentences.
Wernicke’s aphasia
A condition, caused by damage to Wernicke’s area, that is characterized by difficulty in understanding language, and fluent, grammatically correct, but incoherent speech.
Occipital lobe
The lobe at the back of the brain that is devoted primarily to analyzing incoming visual information.
Parietal lobe
The lobe at the top of the brain that contains mechanisms responsible for sensations caused by stimulation of the skin and also some aspects of visual information.
Contains somatosensory cortex.
Frontal lobe
The lobe in the front of the brain that serves higher functions such as language, thought, memory, and motor functioning.
Prosopagnosia
Condition caused by damage to the temporal lobe that is characterized by an inability to recognize faces.
Double disassociation
A situation in which a single dissociation can be demonstrated in one person and the opposite type of single dissociation can be demonstrated in another person (i.e., Person 1: function A is present, function B is damaged; Person 2: function A is damaged, function B is present).
Doris Tsao
(2006) found that 97 percent of neurons within a small area in the lower part of a monkey’s temporal lobe responded to pictures of faces but not to pictures of other types of objects. This “face area,” as it turns out, is located near the area in humans that is associated with prosopagnosia.
Functional magnetic resonance imaging (fMRI)
(1990) A brain imaging technique that measures how blood flow changes in response to cognitive activity.
Voxels
Small cube-shaped areas in the brain used in the analysis of data from brain scanning experiments.
Task-related fMRI
The fMRI response that occurs in response to a specific cognitive task.
Fusiform face area (FFA)
An area in the fusiform gyrus on the underside of the temporal lobe that contains many neurons that respond selectively to faces.
Parahippocampal place area (PPA)
An area in the temporal lobe that contains neurons that are selectively activated by pictures of indoor and outdoor scenes.
Extrastriate body area (EBA)
An area in the temporal cortex that is activated by pictures of bodies and parts of bodies, but not by faces or other objects.
Multidimensional nature of cognition
The multidimensional nature of cognition refers to the fact that even simple experiences involve combinations of different qualities.
Distributed representation
Occurs when a specific cognition activates many areas of the brain.
Memories can also do this.
Neural networks
Interconnected areas of the brain that can communicate with each other.
There are complex structural pathways called networks that form the brain’s information highway.
Within these structural pathways there are functional pathways that serve different functions.
These networks operate dynamically, mirroring the dynamic nature of cognition.
There is a resting state of brain activity, so parts of the brain are active all the time, even when there is no cognitive activity.
track-weighted imaging (TWI)
A technique for determining connectivity in the brain that is based on detection of how water diffuses along the length of nerve fibers.
Connectome
The “wiring diagram” of neurons in the brain. Structural connections mapped out.
Functional connectivity
The extent to which the neural activity in separate brain areas is correlated with each other.
resting-state fMRI
The fMRI response recorded when a person is at rest (not involved in any cognitive tasks)
resting-state functional connectivity
Bharat Biswal and coworkers (1995). A method for determining functional connectivity that involves determining the correlation between the resting-state fMRI in separated structures.
Seed location
The area of the brain associated with carrying out a specific cognitive or motor task that serves as the reference area the resting-state functional connectivity method.
Time-series response
The way the fMRI response changes over time.
Test location
When measuring resting-state functional connectivity, the activity at the test location is compared to the activity at the seed location to determine the degree of functional connectivity between the two locations.
default mode network (DMN)
Network of structures that are active when a person is not involved in specific tasks.
Questions for understanding the physiology of cognition has depended on advances in technology
The Representation Question, The Organization Question, and The Communication Question.
Six Common Functional Networks Determined by Resting-State fMRI
Visual: Vision: visual perception
Somato-motor: Movement and touch
Dorsal Attention: Attention to visual stimuli and spatial locations
Executive Control: Higher-level cognitive tasks involved in working memory and directing attention during tasks
Salience: Attending to survival-relevant events in the environment
Default mode: Mind wandering, and cognitive activity related to personal life-story, social functions, and monitoring internal emotional states
