Understanding the Basics of The Brain

1. UNDERSTANDING THE BRAIN :
THE NEUROBIOLOGY OF
EVERYDAY LIFE
FINAL PROJECT
Understanding the Basics of The Brain
By:
Penmetsa Swetha

2. INTRODUCTION
Let’s look at a small story,
“It was a bright and sunny morning with white fluffy clouds
drifting across the sky. She woke up when the gold
spilling hit her face like a warm touch, her dog wagging
its tail seeing her, she had a good tea, with her eyes
feasted on the beauty of nature, and ears blessed with
the sounds of chirping birds and rustling leaves, good
exercise and a fresh mind to start her daily curriculum...”
We are able to sense, understand and do everything
because of our brain. So let’s look at some basic
information about brain.

3. THE BRAIN
Everything we do depends on the messages that are sent from the brain along the spinal
cord and to the rest of the body.
The brain is an amazing three-pound complex organ that is embedded inside a bony skull
and washed by protective fluid(Cerebrospinal fluid). It controls all the functions of
the body, including the vital functions like breathing and heartbeat.
Neuron:
The brain is made up of specialized cells called neurons. They transmit chemical signals
and electrical impulses in the brain(basic building blocks of the Central Nervous
System) through synapses. Specialized chemicals called Neurotransmitters help the
transfer of electrical impulses across the synapse so that one neuron can excite
another. 85 billion in number.
Glial cells are non-neuronal cells that provide structure and support(nourishment,
protection) to neurons.
Meninges:
The brain and the spinal cord are covered and protected by three layers of tissues called
Meninges. From the outside layer to the inside: The Dura mater, Arachnoid mater,
and Pia mater.
Nervous system: In vertebrates, it consists of two main parts.
Central Nervous System- Brain, Spinal Cord
Peripheral Nervous System-Consists of nerves branching out
from the brain and spinal cord.

4. Regions of the Brain
The brain has three major regions:
 Cerebrum
 Cerebellum
 Brainstem
 Limbic system
Cerebrum: The largest part of the brain, the cerebrum consists of left and right hemispheres, both are
joined together by Corpus callosum, that transmits a message from one side to another, each
hemisphere controls the opposite side of the body. Cerebrum performs higher functions like
interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning,
and fine control of movement.
 The left hemisphere (dominant hemisphere)controls speech, comprehension, arithmetic,
writing, and language.
 The right hemisphere controls creativity, spatial ability, artistic, and musical skills(prosody)
verbal communication.
Cerebellum: is located under the cerebrum. Its function is to coordinate muscle movements,
maintain posture, and balance.
Brainstem: acts as a relay centre connecting the cerebrum and cerebellum to the spinal cord. It
performs many automatic functions such as breathing, heart rate, body temperature, wake and
sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing.
Limbic system: its present deep inside the brain. It links the brain stem and cerebral hemispheres. It
includes the structures which play a key role in memory(The Hipppocampus, The Amygdala).

5. Frontal lobe Functions
 Attention and concentration
 Self-monitoring
 Organization
 Speaking (expressive language) broca’s
area
 Motor planning and initiation
 Awareness of abilities and limitations
 Personality
 Mental flexibility
 Inhibition of behaviour
 Emotions
 Problem solving
 Planning and anticipation
Parietal lobe functions
 Sense of touch
 Spatial perception
 Differentiation (identification) of size, shapes,
and colours
 Visual perception
Temporal lobe functions
 Memory
 Understanding language (receptive language)
 Sequencing
 Hearing
 Organization
Occipital lobe Functions
 Vision
Lobes of the Brain
The cerebrum is divided into four lobes:
frontal, temporal, parietal, and occipital
• Each lobe of the brain does not work alone , they may be divided once again into
area that serve their specific function.

6. Memory
Four parts of the brain are closely associated with memory. They are the
Amygdala: Mainly regulates fear and aggression. It helps store memories related to these
emotions. It also helps transfer new information into long-term memory.
Hippocampus: Involved in recognition and spatial memory. This part of the brain also
helps give memories meaning and connect them to other memories. Transfer new
memory information to long term memory.
Cerebellum and the Prefrontal cortex: helps in consolidating procedural memory, motor
learning and conditioned responses.
 Memory is a complex process that includes three phases: encoding (deciding what
information is important), storing and recalling.
Short-term memory, also called working memory, occurs in the prefrontal cortex. It
stores information for about one minute and its capacity is limited to about 7 items. For
example, it enables you to dial a phone number someone just told you. It also
intervenes during reading, to memorize the sentence you have just read so that the
next one makes sense, taking notes while teaching a new class.
Long-term memory is processed in the hippocampus of the temporal lobe and is
activated when you want to memorize something for a longer time. This memory has
unlimited content and duration capacity. It contains personal memories as well as facts
and figures.
Skill memory is processed in the cerebellum, which relays information to the basal
ganglia. It stores automatically learned memories like tying a shoe, playing an
instrument, or riding a bike, opening a bottle cap before drinking.

7. Example: Alzheimer’s disease
Alzheimer’s disease(AD) causes degeneration of neurons, mostly seen in the people
of the age group 65 years and older and is the most common cause of dementia.
The main symptoms are dementia, cognitive impairment and behavioural changes.
 In a healthy human being the movements, feelings, memories, sensations, are of the
result of the communication between billions of neurons that are present in the brain.
There are other cells in the brain, namely Astrocytes and Microglia which clear the
waste or the debris and protects the neurons.
 But in case of a person with Alzheimer's disease, changes in the brain result in
destroying a healthy balance. Based on the studies of AD, this imbalance involves
two proteins called beta-amyloid and tau. The tau protein gets abnormally
accumulated and forms tangles inside the neuron and beta-amyloid clumps and
forms plaques which accumulate between neurons.
 Amyloid plaques are a clump of oligomers that are present in different forms. We
can not specify which forms are toxic but they are shown to weaken the
communication and plasticity at the synapse, which could be the reason for the
inability of AD brain from forming or retrieving memories. Neurons are not the only
cells that are affected in AD, the microglia takes up the beta-amyloid and gets
activated which results in the release of inflammatory cytokines that damage
neurons.

8.  The microglia starts to remove synapses by phagocytosis. These activities result in
break-down of synapses and death of neurons which ultimately results in atypical
patterns of activity and the brain can not process and store information normally.
 Some of the beta-amyloid effects are arbitrated by tau protein. In AD, tau is modified
to acquire an abnormal shape causing it to cut off from the microtubules and moves
from axon to cell body. Even tau comes in a variety of forms which makes it difficult
to understand which one results in the disease and form tangles in the due course
kills neurons.
 Another problem observed in animal models is that the misfolded tau proteins can
spread across synapses and cause misfolding of tau protein in the healthy neuron as
well. This pattern of spreading across the brain leads to progression from early to
late stages of AD.
 Areas of the brain affected by AD: Affects the neurons and the connections
between them. The connections that are lost in the brain are involved in memory,
including the entorhinal cortex and hippocampus(reduced in size). Hippocampus is
needed for memory retrieval, so that’s why people with early stages of AD remember
their picnic in childhood but not what they had for breakfast in the morning. The
amygdala is generally affected later stages, so a person with AD often recall
emotional aspects of something even if they don’t recall the occurring content(to say
the limbic system is affected). During the ageing of a healthy brain, there will be a

9.  Damage to left hemisphere problem related to semantic memory and language.
 Damage in the visual system, in the temporal lobe, so they may even forget familiar
faces but they might recognize them through their voice case visual and hearing
pathways are different.
 Damage in lobes-parietal(a problem in reading, recognizing faces etc), frontal(no
proper planning, organization, behaviour), temporal(no recall of episodes) as
functions mentioned above.
 There is no cure but only one certainty, continuous support for basic and clinical
research.

10. Few Brain Disorders(extra info.)
A healthy brain is our gift! We are lucky to have a well-functioning brain. Lets look at
some brain disorders mentioned in the module by prof. Peggy Mason.
 Multiple Sclerosis: Demyelinating disease, in this the immune system attacks the
myelin(CNS), as prof Peggy Mason explained the problem is either in the
oligodendrocytes or the interaction between the oligodendrocytes and the axon, in
which case you get a central demyelinating disease, and the most common by far is
multiple sclerosis.
 Charcot-Marie-Tooth: Diverse group of hereditary neuropathies, demyelinating
disease in Schwann cells (PNS)
 An inflammatory, acute demyelinating disease called Guillain–Barré in Schwann
cells. (PNS)
Symptoms include disruption in neural code if there is demyelination
 Gliomas: tumours of glial cells (mass of tissues formed by uncontrolled growth of
glial cells) that are formed in the brain and spinal cord.
 Meningioma: Tumours caused by meningeal cells increase the pressure within the
skull.
 Pituitary adenoma and Schwannoma are caused by tumours of pituitary cells and
Schwann cells respectively.
 Acoustic neuroma/ Vestibular neuroma a benign tumor that develops on the nerve
which connects the ear and brain.

11.  Parkinson's disease: disorder in CNS, that affects movement, often include
tremors, nerve cell damage in the brain and causes a decrease in dopamine levels,
basal ganglia disorder, inactive direct pathway will lead to few movements being
performed.
 Myasthenia gravis: interruption of communication between nerve and muscle at
neuromuscular junctions. (error in the transmission of nerve impulses to muscles).
 Craniorachischisis : nerve tube defect in which the brain and spinal cord remain
open.
 Posterior spina bifida: incomplete closing of spine and membranes around the
spinal cord during early development. The cerebellum is pulled and has a bulge like
appearance.
 Anencephaly: it is a condition in which the forebrain and cerebrum are not formed.
The brain is not covered due to incomplete formation of the scalp and skull.
 Exencephaly: The brain located outside the skull.
 STROKE: (cerebrovascular accident) Damage to brain from passage of proper blood
supply.
a point to be mentioned is that brain don’t store glucose so it requires continuous supply
of blood for proper function.
 Aphasia: a disorder in the left hemisphere which results in difficulty in speaking.
 Huntington’s chorea: inherited disorder which involves dance like movements,
basal ganglia disorder inactive indirect pathway would result in too many
movements.

12. Thank you note.......
Till now we went through a journey of the brain where we can see how we
remember(memory), the reason we speak(Broca’s area), what not, all the
possible things we do in our everyday routine and even few diseases
related to our brain.
I found a lot of answers from this course and even though I am not student of
Psychology, my passion towards understanding the brain made me opt this
course. Professor Peggy Mason always explained beyond my expectation
and I am glad that I opted this course. Every module is explained in the
form of a story which created interest in knowing more and more about it.
Thank you,
Professor Peggy Mason