Basics of Neuroscience

James J. Messina, Ph.D.

Structures of the BrainFacts 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 Components1. 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 brain2. 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 SystemLimbic 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 (Rasia-Filho, 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 anotherNeurons•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 presynaptic2. 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 & anxiety1.Glutomate: excites receiving neurons2.GABA -Gamma amino-butryic acid: inhibits receiving neurons

Neurotransmitters (2)Neuromodulators1.Serotonin: regulates states of consciousness, mood and anxiety, it also regulates sleep & digestion & affects appetite, sleep & sexual behavior. Most antidepressants aim at increasing its effect2.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 stressors3.Norepinephrine: Its function is to alert & arouse. It regulates alertness, anxiety & tension & is secreted by adrenal glands in response to stress or arousal4.Acetylcholine: promotes wakefulness & learning

Neurotransmitters (3)

Neuropeptides – are built from peptides which is a kind of organic molecule1.Opiods – buffer stress, provide soothing & reduce pain, & produce pleasure - these include the endorphines2.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 & trauma2.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 BrainThere are some basic rules of eating to follow to keep the brain healthy1.Eat a well balanced diet on a daily basis – lots of proteins & lots of vegetable2.Eat at least 2 servings of fish a week3.Limit fat consumption to 30% of caloric intake4.Reduce amount of sugar intake on a daily basis-avoid refined sugars5.Avoid foods which body is allergic to

Take Supplements to Help brain

1. Multivitamin/multimineral supplement2. 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 longitudinally-measured cognitive decline•Humans need high levels of cognitive activity throughout their adult life to optimize their cognitive functioning later on as they age