Title: NeuroPhysiology
1NeuroPhysiology
- Physiology is the study of the function of
organisms - Psychology challenges us to think of how
physiology might affect our behavior - Mind Body Problem Does our mind affect our body?
Does our body affect our mind? Some think that
brainbehavior, therefore if you can understand
the brain, then you can understand behavior. - Descartes claimed that the pineal gland was the
interface between mind and the rest of the brain.
Interactions between the mind and body are
two-way. In perception, the physical states of
the world influence our bodies which influence
our brains which via the pineal gland influence
our behavior.
2Continuity Problem
- Are humans and animals the same?
- Most religions say humans are very different than
animals and therefore can not be thought of in
the say way. - Some scientists maintain that humans differ by
degree form other animals as part of a continuum. - Continuity-humans are more similar than different
from other animals.
3Brain and Computers
- If you give a computer a command it has never
encountered and is not programmed to understand
then it will not do the command--this is same for
the human brain. However, over time the brain
can learn this information, but the computer will
never know the command unless it is programmed
differently. - Www.ecs.soton.ac.uk/harnad/Hypermail/Thinking.Psyc
hologically98/0020.html
4Ways to Study the Brain
- Lesion method-cutting part of the brain
- Ablation method-destruction of part of the
brain - These two types are never used, this is used on
animals and not much in use today. However,
humans can be used if they suffered from an
injury. - Simulation method-electric and chemical
simulation which allows researchers see what
stimulation to different parts of the brain
causes. This is in extensive use today. - EEG(electroencephalgram)- recording technique of
the neuron activity - Biochemical techniques- used to map
neurotransmitters
5MRIs and CAT Scans
- MRIs(magnetic resonance imaging) are imaging
techniques which use magnetism - CAT scans(computer assisted tomography) uses
x-rays - PET scans(position emission tomography) uses the
brains metabolic activity
6The Neuron
- Basic unit of nervous system
- there are many of them 10-12 billion in humans
- mostly found in the Central Nervous System 70
- Three types of Neurons
- Afferent or Sensory neurons-run from sensory
organs to CNS - Efferent of Motor Neurons-run from CNS to muscles
- Interneurons or Multipolar neurons-found mostly
in the brain and are connected to other neurons
7Neurons continued
- Axon- or nerve fiber is a very special part of
the neuron, it carries the information away from
the cell in the form of bioelectric signals also
known as nerve impulses.
8Nerve Conduction within Neurons
- In most animals and in humans nerve conduction is
electro-chemical process - Electric occurs within the neuron
- Chemical occurs between the neurons
- Depolarization makes it electrical, this is when
the membrane becomes less negative. When the
neuron is at rest it is not conducting an impulse
then it is polarized, this is due to the inside
of the membrane is more negatively charged than
the outside of the membrane. The neuron can
change from polarized to depolarized by the
movement of Na and K ions across the membrane.
9Neurotransmitters
- Neurotransmitters are biological messenger
molecules that carry information.
- Neurotransmitters communicate across a synapse in
two ways - 1)EPSP (excitatory postsynaptic
potential)-information is transmitted - 2)IPSP (inhibitory postsynaptic potential)-
transmission is ceased
10Myelination
- Myelin is layers which have a higher proportion
of lipids than other surface membranes. Myelin
is wrapped around Schwann cells.
- There are two functions of myelin1.)insulation
for the axon 2.)to speed nerve conduction
- Myelinated axons appear to be whiter, therefore
are called white matter. They are mostly found
in the peripheral nervous system. - Unmyelinated axons appear to be gray, therefore
are call gray matter. They are mostly found in
the central nervous system.
11All-or-None Law
This is the concept of how neuron impulse
conduction. If a neuron responds, then it
responds completely. Thus, a nerve impulse is
conducted whenever a stimulus of threshold
intensity or above is applied to an axon and all
impulses carried on that axon are the same
strength. A greater stimulation causes the rate
of the neuron impulses to increase not the
intensity of the impulse. The rate of the
impulses can only be so high, though, due to the
refractory period of the neuron. Each neuron
must have a brief refractory period which is
where the threshold stimulus will not trigger
another impulse on an axon.
12Nervous System
The central nervous system (CNS) includes the
brain and the spinal cord. The peripheral
nervous system is everything else. The
autonomic nervous system is a part of the
peripheral nervous system, and it is the part
that regulates functions that run without our
conscious control, such as breathing, heart rate,
and digestion.
13Organization of the Brain
The brain is made up of neurons. One organizing
principle of the brain is redundancy (different
parts of the brain contribute to solving the same
problems) Another organizing principle is
bilateral symmetry (divides the brain into a
right and a left half). Animals that do not show
this left-right symmetry are rare. The brain and
body are connected contralaterally (the left side
of the brain controls the right side of the body
and vice-versa). The last organizing principle
is evolutionary organization. The areas nearest
to the spinal cord end are the oldest, and the
areas furthest from the spinal-cord end are the
newest. The oldest areas are the most important
for survival.
14Hemispheric Specialization
The brain is divided into a left and a right
half, and those halves are connected by a fibrous
band of tissue called the corpus callosum. The
corpus callosum serves as a bridge for
information from one half of the brain to the
other. Although the two halves are physically
similar, they function differently.
Bilateral symmetry is the symmetry everybody is
aware of, and to many people this is symmetry
itself. Bilateral symmetry occurs when two halves
of a whole are each other's mirror images. It is
also called mirror symmetry.
15Hemispheric Specialization Cont.
The left hemisphere Is in charge of language
functions and logical thought. Speech, song, and
writing are all examples of left hemisphere
functions however, functions such as speech and
song are controlled by different areas in the
left hemisphere. The right hemisphere Is
responsible for such things as the perception of
rhythm, spatial-relation skills, and abstract or
intuitive thought. The right hemisphere is less
controlled by logic. There are some people who
show the opposite pattern of hemispheric
specialization. Those people have language
functions in the right hemisphere, and rhythm,
spatial relation skills, and abstract/intuitive
thought in left hemisphere.
16Hind Brain
The medulla is the first part of the hind brain
from the spinal cord. The medulla contains the
centers that regulate breathing and heart rate.
That is why damage to the medulla is usually
fatal. The pons are the next brain area up from
the spinal cord. The pons are centers that
control wakefulness and alertness. The
reticular formation contains information. It is
a small tube that is inside the larger tube of
the brain stem. Within are many axons, which
communicate with the body. The cerebellum is
the first big bump on the brain. Its main job is
the control of gross motor function.
17Hind Brain Pic
Pons Controls paradoxical sleep Medulla
Controls vital functions (breathing, heart rate,
and respiration) Spinal Cord Mediates spinal
reflexes, receives sensory information
(afferent), transmits motor information
(efferent)
18Colliculi
The inferior colliculus is responsible for
reflexive responses to auditory stimuli. It
controls your response to loud noises although
sometimes you can control your response. The
superior colliculus controls visual reflexive
stimuli. It is responsible for making you look
at bright lights and other things. Together,
the inferior and superior colliculus make up the
colliculi.
19Cerebrum
Also called the cortex, or neocortex. The
newest and largest part of the brain. A great
deal of the surface has no function that can be
determined. Those surface areas are called
associative areas, and are probably responsible
for a great deal of our cognitive capacity. The
cortex is divided up into five lobes. The four
lobes on the surface are the frontal, parietal,
occipital, and temporal. The fifth lobe is
underneath the surface lobes, and is called the
limbic lobe or limbic system.
20Cerebrum Cont.
The frontal lobe The frontmost portion, this
area controls motor functions or movements.
Also, it controls higher order functions,
planning, thinking, and worrying. The body parts
being controlled are mapped onto this portion of
the cortex. Some parts, such as the hands and
lips, receive more brain tissue than other parts,
such as the torso. The parietal lobe This area
monitors sensory information and body awareness.
The body parts here are also mapped onto the
sensory areas of this parietal lobe, but that map
is not exactly like the one mentioned above.
21Cerebrum Cont.
The temporal lobe Receives sensory input from
the ears. Sounds are analyzed and interpreted as
language. The occipital lobe Receives sensory
input from the eyes. It analyzes and interprets
visual stimuli. The analysis and interpretation
of vision is extremely complex and accounts for
the largest percentage of the brain's activity.
The limbic lobe Also called the limbic system.
This is the ancient cortex, sometimes called the
paleocortex. The neocortex has taken over most of
the limbic system's original functions. Now, the
limbic system primarily controls emotional
behaviors and memories.
22Brains and Evolution
Brain power evolves because there is a need for
it. Some environments require all of it for us
to survive and reproduce. Evolutionary changes
are constrained by physical and temporal factors.
Going up the evolutionary chain, we see more
bumps or convolutions (folds) on the brains of
the higher evolved animals. Animal brains are
laid out horizontally, but the human brain is
laid out at nearly a right angle. When humans
evolved into creatures that walked upright, our
heads rotated forward and the brain had to
follow. Making the head bigger might have been a
solution, but the size of the human female's
birth canal put a constraint on that. The brain
got bigger, the head stayed about the same size,
and the brain folded up to fit inside the size of
the head.
23Endocrine System
This is an integrating system (a system that
helps to organize behavior and physiology). This
system uses ductless glands that are specialized
tissues that secrete hormones directly into the
bloodstream. Hormones are fairly simple chemicals
that are absorbed by other tissues, known as
target sites, and then used by those
tissues. Endocrine action includes physical
growth and the menstrual cycle. In humans,
physical growth is mediated by a somatotrophic
hormone (growth hormone) and it ceases to work
during adulthood. During adolescence, growth
hormone and the sexual hormones combine to
produce the adolescent synergistic growth spurt.
A synergism is when two or more elements combine
to produce a greater effect. Synergistic effects
also happen when certain drugs are taken.