Basics of Neuroscience
James J. Messina, Ph.D.
Structures of the Brain
Facts about human brain
weighs about 3 pounds or about 2% of the body’s weight
• Contains 1.1 trillion cells, including 100 billion neurons
• Neurons on the average have 5000 connections called
synapse from other neurons (Linden, 2007)
• Brain uses 20-25% of the body’s oxygen and glucose
even though it is only 2% of the body’s weight
(Lammert, 2008).
• Brain is always working and performing its functions
• Brain uses the same amount of energy
• when the body is asleep or when awake it is hard at
work thinking (Raichle & Gusnard, 2002).
The Brain and the Mind
• The brain interacts with the other systems in the
body, which interacts with people and the world
around it
• The brain is shaped by the mind.
• In reality the mind is a creation of the brain, the
body, the natural world and the human culture
and the mind itself (Thompson and Varela, 2001).
• So it is a simplification to say that the Brain is the
primary influence on or the basis of the human
mind.
The Three Human Brains
• Aggressive Brain: which lies in the primitive
portion of the brain
• Emotional Brain: which entails the Limbic
system
• Analytical Brain: which involves these
components of the brain:
• The brain reaches its maximum number of
synaptic connections and its greatest
metabolic activity around the age of 3 or 4.
Primary Components of Human Brain (Part 1)
• The Cerebral Cortex (Described in next slides)
• Anterior (frontal) Cingulate Cortex (ACC) – Steadies
attention and monitors plans. It helps to integrate
thinking and feeling (Yamasaki, LaBar, and
McCarthy, 2002). A cingulate is a curved bundle of
nerve fibers
• Insula – Senses the internal state of the body,
including those “gut feelings” which people
experience. It helps a person to become empathic.
It is located inside the temporal lobes on each side
of the brain
• Thalamus – Major relay station for sensory
information. It relays sensory information from the
outside world directly to the amygdala to identify
the importance of the stimuli
Primary Components of Human Brain (Part 2)
• Brain Stem – Sends neuromodulators such as serotonin
and dopamine to the rest of the brain
• Corpus Callosum – Nerve bundle which passes
information between the two brain hemispheres - vital
for integrated thoughts, feeling and action
• The Pons – (bridge) Connection between the lower
brain and the mid-brain. It affects physical arousal,
including blood pressure and responsible for
heightened physical arousal in anxiety. Nuclei within
the pons are important in rapid eye movement (REM)
sleep.
• Cerebellum - Regulates body movement and
responsible for body and limb position, relating to
balance, posture, walking etc. Integrates information. It
is assumed that the Cerebellum plays an important role
in dreaming, memory, and other functions.
The Cerebral Cortex
• The motor cortex – mediates motor activity
• The premotor cortex - plans complex motor
activity
• Prefrontal Cortex (PFC) – Makes meaning of
sensory input.
– The orbitofrontal cortex (OFC) - Controls working
memory
– The anterior cingulate gyrus (ACG) – Connects
directly limbic system
Prefrontal Cortex (PFC)
• Makes meaning of sensory input
• Sets goals, makes plans, directs actions, and
shapes emotions
• Processes information, maintains conscious
attention, and forms behavioral responses
• Guides and sometimes inhibits the limbic system
• Conducts executive reasoning and is critical for
sequencing behavior
• Handles working memory
Prefrontal Cortex’s Components
1. The orbitofrontal cortex (OFC) –
• Controls working memory
• Consolidates long term memory
• Compares information with other data coming to
it from other information centers of the brain
2. The anterior cingulate gyrus (ACG)
• Connects directly to the structures of the limbic
system
• Filters and amplifies information from lower
regions to and from the prefrontal cortex
Limbic System
Limbic System
– central to emotion and motivation and memory
– includes cortical as well as subcortical structures
– consists of the structures that ring the upper part of the brainstem
• Basal Ganglia – Involved with rewards, stimulation seeking and
movement. “Ganglia” are masses of tissues
– Cingulate gyrus – allows shifting of attention, cognitive flexibility,
adaptability, and helps the mind move from idea to idea
• Hippocampus – Forms new memories and idetects threats.
• Amygdala - Functions as the “alarm bell” for the brain that
responds to emotionally charged or negative stimuli (RasiaFilho, Londero & Archaval, 2000)
• Hypothalamus - Regulates primal drives such as hunger and
sex & activates the pituitary glands
• Pituitary gland – it makes endorphins and triggers hormones.
The Limbic System
The Lobes of the Brain
Left Hemisphere of Brain
• Organizes information, understands sequences &
comprehends time in conjunction with activities or
events, putting events in sequential order & placing
them in time
• where verbal work & making meaning of experience
occurs
• Forms symbols (language and math) for experience
• Creates explanations for experience
• Inhibits activity of right hemisphere which deals with
emotions
• Moderates emotional information which goes into
right side of brain
• Mediates memory, nonverbal, emotional
responsiveness of right-side brain functions
Right Hemisphere of Brain
• Responsible for recognizing faces, reading emotions,
assessing emotional significance of event in
conjunction with data from senses which it interprets
• Specialized for nonverbal recognition & emotional
memory - vital for quick & accurate response to world
in which human lives
• Strong role in creativity & nonverbal problem solving
• Creates novel responses to both practical & emotional
situations
• Comprehends spatial relationships
• Alert for & creates cadence & rhythm in speech,
movement, music
• Regulates nervous system & hormonal response
coming in from senses.
Role of Brain Hemispheres
• Left side of brain controls right side of body & right
side of brain controls left side of body
• Previous slide demonstrates: left eye's image is
translated on right side of brain & right eye's image is
translated on left side of brain
• Image which person perceives comes after a process in
brain in which left & right side images are translated or
decoded by left & right side of brain & then made
sense for observer
• Any sight, thought, sound, smell, touch, or taste a
person has is simply a series of biochemical electrical
impulses which are sent out by senses to brain
• This is physiological process by which all senses &
thinking are impacted
Cause of Faulty Perceptions
• If human has faulty perceptions it can impact
the way human thinks, feels and acts
• As a result of faulty perceptions which come
from obscuring translation of faulty
perception can impair problem solving,
decision making & conflict resolution
• Brain take time to sort out what senses are
sending it
The Evolving Brain
Inside brain are three levels of development of
brain
• Reptilian - Brain stem is “reptilian brain” from
which rest of brain has evolved is simplistic,
concrete, fast, and motivationally intense
• Paleomammalian – Limbic System
• Neomammalian - Cortical tissues relatively
recent, complex, conceptualizing, slow &
motivationally diffuse sit atop subcortical & brain
stem structures
Evolving Brain Impact
• Modern cortex of brain has great influence over rest of brain
• It’s been shaped by evolutionary pressures to develop ever
improving abilities to parent, bond, communicate, cooperate
love (Dimbar & Shultz, 2007).
• Cortex is divided into two “hemispheres” connected by corpus
callosum
• In evolution of brain left hemisphere came to focus on
sequential and linguistic processing & right hemisphere
focused on holistic & visual-spatial processing
• Two hemispheres work closely together & it is often hard to
differentiate their different functions as brain operates
• Many neural structures in evolving brain were duplicated so
that there is one in each hemisphere
• Usual way of talking about components of brain is to refer to
structure as a single entity e.g. cerebellum
So How Does the Brain Work?
Brain Pathway:
• Power line which connects two brain regions
• Made up of interconnected neurons along which signals
are transmitted from one brain region to another
Neurons
• Brain has over 100 billion neurons
• Neurons on average have 5000 connections called
synapse from other neurons (Linden, 2007)
• Bio-chemical electrical impulses create a cascade of
effects based on messages sent to various organ
receptors of body
• Neurons process information by receiving, integrating &
transmitting information.
Components of Neurons
• Cell body – sends out dendrites
• Axon – when a neuron fires an electrochemical
wave ripples down from its axon which is fiber
which extends toward other neurons it is sending
signals to
• Dendrites - are spikes from neuron which receive
neurotransmitters from other neurons
• Myelin – fatty substance that insulates axons
• Terminal Buton which faces synapse
Components of Neuron Synapse
1. Terminal Buton:
• End of a neuron which contains
neurotransmitters
• Referred to as presynaptic
2. Receptors:
• On end of receiving neuron referred as
postsynaptic
• Through which neurotransmitters are
transmitted
Neurochemicals
• Major chemical inside brain that affect neural
activity
• These chemicals have different functions.
Neurotransmitters
• All neurotransmitters affect functions throughout body
• Brain is made up of billions of brain cells called Neurons
• Neurons transmit information by means of electrical
conduction within nerve cells and between nerve cells
• Message once carried through body cell (Axon) crosses
space called Synapse to new receiving cell
• Tip of neuron axon-tiny sacs contain neurotransmitter
chemicals which are automatically released by sending
nerve cell
• Neurotransmitter chemicals excite receiving cell causing
cell to fire to send message through its own body-Axon to
next receiving cell
• Once message received neurotransmitter is deactivated &
taken up from synapse and stored in sacs so as not to cause
repeated firing of receiving cell.
Neurotransmitters (1)
Primary Neurotransmitters associated with
emotional balance, sleep patterns & anxiety
1. Glutomate: excites receiving neurons
2. GABA -Gamma amino-butryic acid: inhibits
receiving neurons
Neurotransmitters (2)
Neuromodulators
1. Serotonin: regulates states of consciousness, mood
and anxiety, it also regulates sleep & digestion &
affects appetite, sleep & sexual behavior. Most
antidepressants aim at increasing its effect
2. Dopamine: influences emotional behavior &
cognition, regulates motor activity & regulates
endocrine activity. It is also involved in rewards &
attention. It promotes “approach” behaviors for
individuals who face stressors
3. Norepinephrine: Its function is to alert & arouse. It
regulates alertness, anxiety & tension & is secreted
by adrenal glands in response to stress or arousal
4. Acetylcholine: promotes wakefulness & learning
Neurotransmitters (3)
Neuropeptides – are built from peptides which is a kind
of organic molecule
1. Opiods – buffer stress, provide soothing & reduce
pain, & produce pleasure - these include the
endorphines
2. Oxytocin – promote nurturing behaviors toward
children & bonding in couples. Associated with blissful
closeness & love. Women typically have more
oxytocin than men.
3. Vasopressin – supports pair bonding & in men it may
promote aggressiveness towards sexual rivals
Other Neurochemicals
• Cortisol – released by adrenal glands during
stress response. It stimulates amygdala &
inhibits hippocampus
• Estrogen – brains of both men & women
contain estrogen receptors which affects
libido, mood & memory
The Nervous System
• Responsible for sensing & reacting to
environment & coordinating bodily functions
of its organ components
1. Central Nervous System (CNS) includes the
brain and the spinal cord
2. Peripheral Nervous System (PNS)
3. Autonomic Nervous System (ANS).
Peripheral Nervous System
• Affects heart & muscles & directs communications
between skin & brain
• Skin is vital for receiving data about external
environment & safety of body
• Changes in pressure, temperature & other
environmental factors cause both conscious &
automatic adjustments to environment.
• Norepinephrine activates PNS which then
activates heart, muscles & extremities
• As norepinephrine increases so does heart rate &
blood pressure & anxious symptoms such as
sweating, flushing & trembling
Autonomic Nervous System
The ANS enervates & controls action of all internal
organs. It consists of three parts:
1. Sympathetic nervous system (SNS) which is
responsible for arousal of brain & body. It is
important in creating physical responses of
arousal under stress & trauma
2. Parasympathetic nervous system (PSNS) which
inhibits arousal. It restores balance to internal
organs & stress response systems
3. Diffuse enteric nervous system which controls
digestion & peristaltic action
Nutritional Care of Brain
There are some basic rules of eating to follow to
keep the brain healthy
1. Eat a well balanced diet on a daily basis – lots
of proteins & lots of vegetable
2. Eat at least 2 servings of fish a week
3. Limit fat consumption to 30% of caloric
intake
4. Reduce amount of sugar intake on a daily
basis-avoid refined sugars
5. Avoid foods which body is allergic to
Take Supplements to Help brain
1. Multivitamin/multimineral supplement
2. Omega-3 Fatty Acid – found in fish oil – 500
milligrams a day because it contains both DHA
and EPA acids which are very beneficial to brain
given that DHA is the predominant structural
fatty acid in central nervous system
3. Vitamin E as Gamma –Tocopherol – this is main
antioxidant in cellular membranes within brain
Supplements for Neurotransmitters
1. Serotonin supplements: Iron, Vitamin B-6
and 5-Hydroxytryptophan and Tryptophan
2. Norepinephrine and Dopamine
supplements: Iron and Vitamin B-6
3. Acetycholine supplement: egg yolks, beef,
liver, or dairy fats or use phosphatidylserine,
acetyl-l-carnitine or huperzine-A
Lifestyle Habits to
Keep the Brain Healthy (1)
1. Physical Activity and Exercise – 3 times
weekly for 45 minutes including some aerobics
• Improves cognitive functions & sustains
cerebral blood flow
• Encourages angiogenesis which is
development of new blood vessels
• Increases neurogenesis & neuronal growth in
hippocampus
Lifestyle Habits to
Keep the Brain Healthy (2)
2. Engaging in intellectually stimulating
activities throughout life
• As people age it buffers against longitudinallymeasured cognitive decline
• Humans need high levels of cognitive activity
throughout their adult life to optimize their
cognitive functioning later on as they age
Download

Basics_of_Neuroscience