NEURON is a nerve cell & a primarily function unit of the
nervous system. Its parts are the following:
Parts of a Neuron
1. Dendrites. The function of dendrites is to receive signals
from other neurons that come in form of chemicals called
neurotransmitters.
2. Soma aka cell body. The soma takes all the information
from the dendrites and puts it all together in an area called
“axon hillock.” The soma contains the nucleus (which contains
the DNA or genetic material of the cell).
3. Axon. Responsible for transmitting information away from
the cell body. It is where the action potential (aka nerve
impulses or spikes; rapid sequence of changes in the voltage
across the membrane) takes place.
4. Myelin Sheath. An insulator material that helps to prevent
signals from degrading.
5. Axon Terminal aka synaptic button. The Axon terminal
causes the release of neurotransmitters and it interacts with
the receptors on the next dendrites.
6. Synapse. Communication between neurons occurs at a
structure.
7. Synaptic Cleft. 40-nanometer wide. Neurons are not
connected to each other they are separated by a
microscopically small space that is called Synaptic Cleft.
8. Presynaptic Neuron. This is the neuron that will give or
pass signals to the other neuron.
9. Postsynaptic Neuron. This is the neuron that will receive
the signal.
COGNITIVE NEUROSCIENCE
Cognitive psychology = cognition, pano ang takbo ng isip
Cognitive neuroscience is a field that studies how thinking
processes are connected to biological elements of the body.
In cognitive neuroscience, they believe that the “brain” is the
hardware and the “thinking process” is the software. “link”
3 Cognitive Neuroscience Techniques (PAB)
1. Post Mortem Studies is the study of the brain of deceased
individuals. Example of post-mortem studies, comparing the
brain of an individual with Alzheimer's and with a normal
brain. Alzheimer's brain is smaller than a normal brain.
2. Animal Studies is studying the brains of animals in order
for us to have conclusions about how the human brain works.
Through this technique, we discover how learning and
memory work. Commonly studied are rats/mice because they
have the most similarities with the human brain.
3. Brain Scanning Techniques (CMPF)
a. Computerized Axial Tomography (CAT or CT
Scan). A type of structural neuroimaging where
a series of x-ray images of the head is used to
construct an overall image of the brain. It has a
relatively low resolution but you can still see
major structural problems.
b. Magnetic Resonance Imaging (MRI). A type
of structural neuroimaging that uses magnetic
fields and radiofrequency energy. It has a better
resolution than a CAT scan.
Hydrogen atoms respond by emitting energy. The
MRI machine receives this energy and can tell what part of
the brain it came from. The machine then uses energy to
construct image (a computer can use that information to
reconstruct an image of the brain that has high spatial
resolution).
c. Positron Emission Tomography (PET). A type
of functional neuroimaging where the patient is
injected with a radioactive substance. The
Substance emits positrons which then emit
gamma rays when they collide with electrons in brain tissue.
The gamma rays will be detected by device. It will give an
image of cerebral blood flow and will show which areas are
most active.
d. Functional Magnetic Resonance Imaging (FMRI). A type of
functional neuroimaging that uses a magnetic field and
radiofrequency energy. It uses the different responses of
oxygenated and unoxygenated blood to detect changes in
blood flow. Uses blood oxygenation level-dependent (BOLD)
in the blood flow to identify the most active areas of the
brain. It will then show which areas are most active along
with a high-resolution structural image. Has the best
resolution among all techniques.
SENSATIONS AND PERCEPTIONS
|Sensation: a process of detecting an environmental stimulus
and converting that stimulus into neural activity
(transduction).
|Thalamus: a brain structure below the cortex as a relay
station to the sensory system then routed to the brain to
process information.
|Perception: the identification and/or interpretation of a
stimulus. It is what’s on with the sensory information that we
take in, its how we make sense of the world we are in so
stimulus perceived depends on a number of characteristics
Important Terminologies
|Absolute threshold: Minimum amount of stimulus intensity
needed for a receptor to react. For example, the absolute
threshold for sound would be the lowest volume of a tone
that can be perceived by individuals.
|Just Noticeable Difference: Minimum change in stimulus
intensity that can be detected.
|Sensory Adaptation: When a sensory receptor cell’s
response starts to decrease after continuous or repeated
stimulation, which reduces the perceived intensity of a stimuli
or stimulus. Sensory adaptation can occur in any of the five
major senses.
|Perceptual Constancy: The tendency to see familiar objects
as unchanging, even if there are slight changes to the
stimulus. This allows us to recognize objects as having
constant shape, size, and color regardless of the viewing
angle, lighting condition, or distance from the object.
|Perceptual Set: Tendency to perceive some stimuli but not
others and to base expectations on past experiences.
*Perceptual constancy and perceptual set are both top-down
processes (that use what a person already knows to influence
the interpretation of incoming sensory information). It’s what
allows us to read a sign even if there’s something missing
letters.
*We can also use bottom-up processing when the brain uses
raw sensory data to create a perception.