cognitive neuroscience
the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language)
Neurons
cells specialized to create, receive and transmit information in the nervous system. Each neuron has a cell body, axon, and dendrites
Nerve Net
The nerve net is a system made up of a network of nerve cells, the impulse of which travels in both directions. Similar to a highway. Allows for nonstop, continuous communication of signals throughout the network
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 nerve net theory
What did Ramon y Cajal discover?
Individual nerve cells transmit signals, and are not continuous with other cells. There is a tiny space between neurons and they do not actually contact each other. Cajal's Neuron Doctrine contradicted the Nerve Net model
Neural Communication
The body's information system is built from billions of interconnected cells called neurons. These are specialized nerve cells that receive and transmit information to other cells in the body.
afferent neurons (sensory neurons)
carry incoming sensory information from the sense receptors to CNS
Efferent Neurons
Carry outgoing motor (action) signal from the CNS to muscles and glands
Interneurons (association neurons)
connect two of any type of neurons
Cell body
the cell's life support center
Dendrites
receive messages from other cells
Terminal branches of axon
from junctions with other cells
Axon
passes messages away from the cell body to other neurons, muscles, or glands
Neural Impulse
Action potential, electrical signal traveling down the axon.
Touch Receptor
A neuron with a specialized receptor in place of the cell body. This receptor response to pressure on the skin
Nodes of Ranvier
a gap in the myelin sheath of a nerve, between adjacent Schwann cells. Action potentials may travel as fast as 268mph. The action potential "skips" over the segments of mylien hopping from one note to the next.
presynaptic terminal
(end bulb or bouton) point where an axon releases chemicals
Gial Cells
A scanning electron micrograph shows neurons (green)and glia (orange), glial cells cerse as the "glue" of the nervous system, providing cohesion and support for the neurons.
Action Potential (Neural Impulse)
A brief electrical charge that travels down an axon. Generated by an exchange of positively charged ions across the axon membrane.
Thresholds for Firing
Neuron receive both excitation and inhibitory signals from many surrounding neurons. When the aggregate sum of excitation (+) signals and inhibitory (-) signals exceed a minimum intensity (threshold) the neuron "fires" - produces action potential
All or None Response
An action potential property. A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not change the strength of an action potential or speed of firing within the neuron. i.e., the intensity of an action potential remains c
Sensorimotor: Reflexive
information is carried from the skin receptors along a sensory neuron to the spinal chord. From here it is passed view inter neurons to motor neurons that leave to muscles in the hand and arm. Because this reflex involves only the spinal cord, the hand je
The Neural Synapse
This is a junction between the axon tip of the sending neuron and the dendrites of the receiving neurons. This 20-40nm space is called the synaptic gap or cleft.
Sensory Neurons
carry messages from sense receptors to the CNS/brain (receive and transduce sensory input)
Motor Neurons
carry messages from CNS/brain toward muscles and glands (transmit an action oriented signal)
Interneurons
carry messages between receptors and other nerve cells (messengers)
Receptors
Receptors are specialized neurons that respond to specific kinds of physical energy and transform that input into an electrochemical message
Neural Transduction
is the transformation of stimulus energy into neural impulses (electrochemical changes occur in the receptors).
Transmission
occurs when signals from receptors travel along a neural pathway to the brain (neuron to neuron chemical communication).
Neurotransmitters
Chemical messengers that relay neural signals between neurons at the synapse, and they travel across the synaptic cleft (gap). These chemicals are released from the sending neuron across the synaptic gap and bind to receptor sites on the receiving neuron.
Reuptake
Process by which excess neurotransmitters in the synapse are reabsorbed back into the sending neurons. This process applies the brakes on neurotransmitter action
Action Potential
Neuron receives signal from environment -Information travels down the axon of that neuron to the dendrites of another neuron
How are action potentials measured?
-Single Unit Recording (SUR) -Microelectrodes pick up electrical signal -Placed near axon -Active for ~ 1 sec
.-The magnitude is not measured per se -i.e., the size of an impulse wave remains consistent (amplitude in mv) -The rate of firing is measured �L
Synapse
space between axon of one neuron and dendrite or cell body of another
Hubel and Wiesel
Feature detectors: neurons that respond best to a specific stimulus
Hierarchical Processing
When we perceive different objects, we do so in a specific order that moves from lower to higher areas of the brain. The ascension from lower to higher areas of the brain corresponds to perceiving objects that move from lower (simple) to higher levels of
specificity coding
representation of a specific stimulus by firing of specifically tuned neurons specialized to just respond to a specific stimulus
Population Coding
representation of a particular object by the pattern of firing of a large number of neurons
Sparse Coding
when a particular object is represented by a pattern of firing of only a small group of neurons, with the majority of neurons remaining silent
Localization of Function
Specific functions are served by specific areas of the brain. Cognitive functioning breaks down in specific ways when areas of the brain are damaged. Cerebral cortex (3-mm thick layer that covers the brain) contains mechanisms responsible for most of our
What happens to when Broca's area is damaged?
With Broca's area damaged language production is impaired. Located in the frontal lobe
What happens when Wernick's area is damaged?
Language comprehension is impaired. Located in the frontal lobe