How do Neurotransmitters Influence the Brain?
Unit III: Biological Bases of Behavior
Group 1: What are neurons, and how do they transmit information?
1. What are neurons, and how do they transmit information?
A neuron is a nerve cell and it is the basic building block of the nervous system.
o Motor neurons control the muscles
Dendrites are the branching extension of the neuron that receive the information and
conduct it towards the cell body
The axon then passes the message along to the neurons or muscles
Myelin sheath is a layer of fatty tissue segmentally encasing the fibers of many neurons
and enables vastly greater transmission speed of the neural impulses as the impulse jumps
from one node to the next
The impulse, action potential, a brief electrical charge that travels down the axon
Group 2: How do nerve cells communicate with other nerve cells?
Santiago Ramon y Cajal (Spanish) (1852-1934) found that there are gaps between nerve
cells- meaning that dendrites and axons do NOT touch
Sir Charles Sherrington (British) (1857-1952) called this a “synapse” or the synaptic
gap/cleft and said that it is < 1/1 million of an inch wide
o Also found that there is a slight delay in the transmission of impulses between
Action potential of impulses reaches terminals at the end of axons and triggers the
release of chemicals called neurotransmitters
Neurotransmitters cross the synaptic gap and bind to receptors on the receiving
Excess neurotransmitters that are sent go back into the sending neuron- this is called
Group 3: How do neurotransmitters influence behavior, and how do drugs and other chemicals
Neurotransmitters are chemicals
located in the brain to allow an
impulse from one nerve cell to another
There are approximately 50
neurotransmitters identified and
billions of nerve cells located in the
Drugs influence neurotransmitters by
sending false messages to the brain.
Neurotransmitters have been linked
to many mental disorders such as
schizophrenia, depression, and
Alzheimer’s. Schizophrenia is a severe
paranoia. Depression is a case of
hating yourself. Alzheimer’s is a case
of having short term memory which can also be extremely severe in some cases.
Group 4: What are the functions of the nervous system’s main divisions?
Group 5: How does the endocrine system – the body’s slower information system – transmit its
The endocrine system is a system that is controlled by the brain and is very closely
related to the nervous system. Not only do they interact with each other but often times they are
confused with each other. They both release molecules that activate receptors but, what is
released from the endocrine system takes a longer amount of time to travel and has effects that
One of the things that are released by the endocrine system is hormones. They travel
through the blood stream and effect tissues including the brain. Hormones are triggered by sex,
food, and aggression and they effect growth, reproduction, metabolisms, and moods. Sometimes
they even get confused with neurotransmitters.
Two of endocrine glands are the adrenal glands and the pituitary gland. The adrenal
glands are the endocrine glands above the kidneys that release adrenaline and noradrenaline that
help arouse the body when under stress. The pituitary gland is the most influential endocrine
gland; it is under the hypothalamus gland and connects the endocrine system to the nervous
Group 6: How do neuroscientists study the brain’s connections to behavior and mind?
- Biological psychology: a branch of psychology concerned with the links between biology and
- Clinical observation: the oldest method of studying brain- mind connections is to observe the
effects of specific brain diseases and injuries
Daniel langleben and his colleagues discovered the FMRI scans located increased brain
activity associated with lying forms increased brain activity
Electroencephalogram (EEG) is used to identify amplified electrical waves evoked by
stimulus in the brain
Positron emission tomography (PET) this depicts brain activity by showing each brain
areas consumption of its chemical fuel, sugar glucose
Magnetic resonance imaging (MRI) scans allows for the head to be placed in a strong
magnetic field, which aligns the spinning atoms, then a brief pulse of radio waves
disorients the atoms momentarily
Functional MRI (fMRI) can reveal the brain’s functioning as well as its structure
Lesion is tissue destruction caused naturally or experimentally
Surgical lesions, electrical stimulation,
recording the brain’s electrical and
neural activity with computers aided
brain scans used by neuroscientists to
connect behavior, brain, and mind
Group 7: What are the functions of important lower-level brain structures?
Medulla= base of brainstem; controls heartbeat and breathing.
Cerebellum= attached to the rear of the brainstem. Processing sensory imput and
coordinating movement output and balance.
Hypothalamus= neutral structure. Directs several maintenance activities like eating,
drinking, and body temperature linked to emotion and reward spinal cord.
Spinal Cord= pathway for neutral fibers traveling to and from brain; controls some
Reticular Formation= helps control arosal
Pituitary Gland= master endocrine gland
Thalamus= relays massages between lower brain centers and cerebral cortex.
Corpus Callosum= axon fibers connecting two cerebral hemispheres
Hippocampus= structure in the limbic system linked to memory.
Amygdala= neutral centers in the limbic systems linked to emotions
Group 8: What functions are served by the various cerebral cortex regions?
The brain is comprised of two hemispheres: The left hemisphere and the right hemisphere. Each
hemisphere is divided into four separate parts called the Frontal, Parietal, occipital and temporal lobes.
The Parietal lobes are located towards the upper rear portion of the skull and are responsible for
processing all of the information recorded using your five senses.
The Frontal lobes are towards the upper front portion of the cerebrum hence the term “frontal” lobe.
They are responsible for your personality, who you are, decision making and problem solving.
The temporal lobes are on either sides of the brain towards the lower portion located deep to the ears.
It stores memory involving hearing, emotion, and language.
The occipital lobe is positioned in the lower rear portion of the cerebrum and is responsible for eyesight
and processing of light
Broca’s Area is located in the frontal part of the left hemisphere of the brain and is responsible for
Wernicke’s area is located in the left cerebral hemisphere and is responsible for language
Aphasia is the disturbance of comprehension of language caused by a dysfunction in the brain
Group 9: What do split brains reveal about the functions of our two brain hemispheres?
What do split brains reveal about the functions of our two brain hemispheres?
People who experienced seizures had a split brain procedure. The seizures were all but eliminated and the
patients with these split brains were surprisingly normal after and their personality + intellect were hardly
affected, despite having their brains split in half.
Sperry (1964) said split brain surgery leaves people “with two separate minds.” Both hemispheres can
comprehend and follow an instruction to copy something—simultaneously—different figures with the left
and right hand.
What does this mean? The brain’s two halves can simultaneously carry out different functions with
minimal duplication of effort (with the split brain).