Transcript Temporal Lobe

Cerebrum
o Largest part of brain
o “Thinking”; voluntary
muscles
o 2 halves
– Right – Abstract
thoughts
– Left – Analytical
thoughts
o Gyri and Sulci allow
for more surface area
– Increased amount of
neurons
Cerebrum
Cerebellum
o Back of brain
o Balance, movement,
and coordination
o Contains 50% of
neurons in brain, but
1/10 its size
o Evolutionary – came
before cerebrum
Medulla Oblongata
o Middle portion of
brainstem
o Controls autonomic
functions
o Relays nerve signals
between spinal cord
and brain
Functional Lobes of the Cerebrum
o Cerebrum is divided
into 2 hemispheres,
each containing 5
discrete lobes.
 Frontal Lobe
 Temporal Lobe
 Parietal Lobe
 Occipital Lobe
Frontal Lobe
o Associated with reasoning, planning, parts of speech,
movement, emotions and problem solving.
o Functionally distinct areas:
 Primary motor cortex – Controls all moving parts
 Medial frontal cortex – Arousal and motivation
 Orbital frontal cortex – Modulate Social behaviors
 Left Postero inferior frontal cortex – Expressive
language function
 Dorsolateral frontal cortex – Working memory
Parietal Lobe
o Associated with movement, orientation, recognition and
perception of stimuli.
o Generates visual-spatial relationships and integrates
these perceptions with other sensations to create
awareness of the path of moving objects.
o Parts of mid-parietal lobe of the dominant hemisphere
involve in calculation, writing, left-right orientation and
finger naming
o Non-dominant parietallobe enables people to be aware
of the environment space, and is important for abilities
such as drawing.
Temporal Lobe and Occipital Lobe
o Temporal Lobe
 Associated with
perception and
recognition of auditory
stimuli, memory and
speech.
o Occipital Lobe
 Associated with visual
processing
 Contains the primary
visual cortex.
Neuron
• Definition: Neurons are
responsive cells in the
nervous system that
process and transmit
information by
electrochemical
signalling.
Nueron
o The main portion of the cell is called the soma or cell body. It
contains the nucleus, which in turn contains the genetic material in
the form of chromosomes.
o Neurons have a large number of extensions called dendrites. It is
primarily the surfaces of the dendrites that receive chemical
messages from other neurons.
o One extension is different from all the others, and is called the
axon. The purpose of the axon is to transmit an electro-chemical
signal to other neurons, sometimes over a considerable distance.
o Longer axons are usually covered with a myelin sheath, a series of
fatty cells which have wrapped around an axon many times. They
serve a similar function as the insulation around electrical wire.
Impulse Transmission
o A nerve impulse travels through the axon to reach the
presynaptic membrane. On reaching, neurotransmitters
are picked up by receptors.
o Once it is picked, the molecule is internalized in the
neuron and the impulse continues.
Types of Neurons
o Three major classes of neurons –
 Sensory neurons
- Stimulus receptors to the brain and spinal cord
 Motor neurons
- Transmit impulses from the central nervous system to
the muscles and glands
 Interneurons
- They provide connections between sensory and
motor neurons.
The Action Potential
o When chemicals contact the surface of a neuron, they change the
balance of ions (electrically charged atoms) between the inside and
outside of the cell membrane
o This effect runs across the cell’s membrane to the axon
o On reaching the axon, it initiates the action potential
o Surface of ion contains ion channels
o When charge enters axon, the channels let the positive charged ions
enter
o Causes the next group of ion channels to do the same, while other
channels return positive ions to the outside.
The Action Potential
o Neurons pump out positively charged sodium ions.
o Pump in positively charged potassium ions.
o High concentration of sodium ions present outside the
neuron ; and potassium ions present inside.
Neurons in Impulse Transmission
• The brain’s great computational abilities are derived from
the communication among its billions of nerve cells. But
the process of neural conduction that lets a nerve
impulse propagate down a neuron would serve no
purpose if it were not coupled with another mechanism:
the synaptic transmission that lets the impulse pass from
one neuron to the next.
Head Injuries
o Skull Fractures
 Any break in bone
surrounding brain
 3 types
• Linear
• Depressed
• Basilar
o Intracranial
Hemorrhages
 Any type of bleeding
within skull
• Subdural/Epidural
Hematoma
• Cerebral Contusion
Head Injuries cont.
o Causes
 2 types of trauma
• Penetrating trauma
– Usually requires
surgery
• Blunt head trauma
o Symptoms
 Blunt head trauma
• Loss of consciousness,
seizures, sensory
impairments, death
 Penetrating trauma
• Usually similar, but
more serious
Head Injuries cont.
o Treatments
Surgery
• Reduce pressure in skull
• Craniotomy, Burr holes, Bone flap removal
Medication
• Prevent seizures
• Decrease pressure
Brain Abcesses
o Definition: A brain abscess is a collection of immune
cells, pus, and other material in the brain, usually from a
bacterial or fungal infection.
• Brain abscesses commonly occur when bacteria or fungi infect part
of the brain. Swelling and irritation (inflammation) develops in
response. Infected brain cells, white blood cells, and live and dead
bacteria and fungi collect in an area of the brain. A membrane forms
around this area and creates a mass.
• While this immune response can protect the brain by isolating the
infection, it can also do more harm than good. The brain swells.
Because the skull cannot expand, the mass may put pressure on
delicate brain tissue. Infected material can block the blood vessels
of the brain.
What causes brain abscesses?
o The more common causes of a brain abscess include viruses and
bacteria. There are three ways a virus or bacteria can enter the body
and infect the brain, including the following:
1. Infection is spread from another area of infection in the body. This
accounts for the majority of brain abscess cases.
2. Infection is spread through the blood stream from the lung or chest
area.
3. Viral or bacterial germs enter directly into the brain through an
open wound in the head.
o Risk factors for developing a brain abscess include the following:
 congenital (present at birth) heart disease
 head injury or skull fracture
 infections of the face or scalp
What are the symptoms of a brain abcess?
o Symptoms may develop slowly, over a period of 2
weeks, or they may develop suddenly.
 In babies and younger children
• Fever
• Sleepiness or less alert than usual
• Poor feeding
 In older children
• Changes in speech
• Problems walking
• Nausea and vomiting
Treatment for a brain abcess:
o A brain abscess is a medical emergency. Pressure
inside the skull may become high enough to be lifethreatening. You will need to stay in the hospital until the
condition is stable. Some people may need life support.
o Medication, not surgery, is recommended if you have:
 Several abscesses (rare)
 A disease that makes surgery dangerous
o You will get antibiotics. Antibiotics that work against a
number of different bacteria (broad spectrum antibiotics)
are most commonly used. You may be prescribed
several different types of antibiotics to make sure
treatment works.
Treatment for a brain abcess:
o


o
Surgery is needed if:
Pressure in the brain continuesor gets worse
Brain abcess contains gas
Surgery consists of opening the skull, exposing the
brain, and draining the abscess. Laboratory tests are
often done to examine the fluid. This can help identify
what is causing the infection, so that more appropriate
antibiotics or anti-fungal drugs can be prescribed.
o Surgery consists of opening the skull, exposing the
brain, and draining the abscess.
Diseases
o Alzheimer’s Disease
 Atrophy of the brain
 Destruction of brain
cells
 No cure, but there are
treatments
(pharmacological)
• Cholinesterase
inhibitors
• Namenda
o Multiple Sclerosis
 Autoimmune disease;
attacks nervous
system
 Immune systems eats
away at myelin
sheaths
 Treatments
• Natalizumab
Diseases
Alzheimer’s Disease
Multiple Sclerosis