Unit 2 - Neuroscience and Behavior

Neuron

a nerve cell; “building block” of the nervous system Icons of Science

Cell Body (Soma)

Life support center of the neuron.

Dendrites

Branching extensions at the cell body. Receives messages from other neurons.

Axon

Long single extension of a neuron, covered with myelin sheath to insulate and speed up messages through neurons.

Terminal Branches of axon

Branched ending of axons. Transmitting messages to other neurons

Synapse

the junction (space) between the axon of one neuron and the dendrite of another

Neurotransmitter

chemicals that carry messages across the synapse from one neuron to another

Action Potential

The “firing”

Resting Potential

the neuron is ready to fire (chilling waiting on orders)

Electrochemical Process

Electrical inside the neuron; chemical outside the neuron (neurotransmitters)

Excitatory

neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential or “fire”

Inhibitory

neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential or “fire”

Reuptake

Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies brakes on neurotransmitter action.

Refractory Period

After a neuron has fired an action potential it pauses for a short period to recharge itself to fire again

Lock & Key Mechanism

Neurotransmitters bind to the receptors of the receiving neuron

Agonists

It excites; It is similar enough to the neurotransmitter molecule that it mimics the effects on the receiving neuron.

Antagonists

It inhibits; It has a similar enough structure to the neurotransmitter to occupy its receptor and block its action.

Acetylcholine (ACh)

vital role in movement and memory

too much – muscle contractions, convulsions

some spider venoms cause floods of ACh

too little – immobility, extreme lethargy

Botulin causes paralysis by blocking its release

Undersupply of ACh has been linked to Alzheimer’s disease

Dopamine

deals with movement, learning, attention & emotion

lack of dopamine has been linked to Parkinson’s Disease

too much has been linked to Schizophrenia

Many drugs cause our brain to flood with Dopamine

Serotonin

involved in mood control, hunger, sleep / arousal

lack of serotonin has been linked to clinical depression (Prozac and other antidepressants raise levels)

Endorphins

“endogenous morphine”

involved in pain control

most addictive drugs work with endorphins (opioids)

Glutamate

Major excitatory neurotransmitter. Involved in learning, memory, and brain development.

Oversupply can over stimulate the brain and cause seizures and migraines

GABA

Major inhibitory neurotransmitter Prevents a neuron from generating a nerve impulse.

Undersupply linked to seizures, tremors, and insomnia

Norepinephrine

Helps control alertness and arousal

Undersupply can depress mood

Substance P

Involved in pain perception and immune response

Oversupply can lead to chronic pain

Efferent (Motor) Neurons

info to body parts for movement

Interneurons

info within central nervous system

Afferent (Sensory) Neurons

info to CNS from body parts

Central Nervous System

brain and spinal cord

CNS

Receives Info from the peripheral and then tells it what to do

Peripheral Nervous System

ll nerves that are not encased in bone

everything but the brain and spinal cord

Divided into Somatic and Autonomic

Somatic Nervous System (Peripheral)

controls voluntary muscle movement

uses motor (efferent) neurons

Autonomic Nervous System (Peripheral)

controls the automatic functions of the body

Divided into sympathetic and parasympathetic

Sympathetic Nervous System

“Fight or Flight” response

automatically accelerates heart rate, breathing, dilates pupils, slows down digestion

Parasympathetic Nervous System

automatically calms the body down after a stressful event

heart rate and breathing slow down, pupils constrict, and digestion speeds up

think, “parachute”

Reflexes

normally, afferent neurons 🡪 spine 🡪 brain & brain sends orders for movement 🡪 efferent neurons

some reactions occur when sensory neurons reach just the spinal cord & spinal cord sends orders

Neural Networks

interconnected neurons

regular connections or routes of communication for different tasks, processes, etc.

body/brain “learns” networks over time

“muscle memory” in sports (“practice makes permanent”)

Brain

made up of…neurons, glial cells (or glia - support neural cells by insulating them, removing waste, etc.), connective tissues, cerebrospinal fluid

can be divided into three major sections: hindbrain, midbrain, forebrain

Glial Cells

They have four main functions: (1) to surround neurons and hold them in place; (2) to supply nutrients and oxygen to neurons; (3) to insulate one neuron from another; (4) to destroy pathogens and remove dead neurons.

Brain stem (hindbrain)

Midbrain: top

Pons: Middle

Medulla (Medulla Oblongata)

Midbrain

Involved in vision, hearing, eye movement, and body movement

Pons

Involved in sleep (REM), swallowing, facial expressions and sensations, bladder control

Medulla

Breathing, Heart Rate, Respiration

Limbic System

“The emotional center of the Brain”

Thalamus, Hypothalamus, Amygdala, and Hippocampus

Thalamus

Switchboard for sensory information (except smell)

Receives sensory and motor information and sends them to appropriate areas of forebrain.

Auditory, visual, tactile, gustatory

Hypothalamus

Body temp, Hunger, Thirst, Sexual Arousal, Endocrine System (Pituitary Gland), Pleasure Center

Amygdala

Fear, Memory of fear, aggression and emotion

Hippocampus

Memory, Short to long, and learning

Ventromedial Hypothalamus (VMH)

Satiety Center: Ceases Hunger

Destruction: Obesity, Never feel full

Lateral Hypothalamus

Stimulates Hunger

Destruction: Skinny, always feel full, starvation

Cerebellum (Little Brain)

voluntary muscle movements, balance, coordination

Injury: Difficulty walking, keeping balance, shaking hands

Cerebral Cortex

Top layer of our brain.

Contains wrinkles called fissures.

The fissures increase surface area of our brain.

Divided into eight lobes, four in each hemisphere (frontal, parietal, occipital and temporal).

85% of the brains weight

20-23 million nerve cells

Linked by over 300 trillion synapses

Glial Cells (9 times as many): Feed and insulate nerve cells

Association Areas

Any area not dealing with our senses or muscle movements are called _______ (allows for complex mental functions)

More intelligent animals have increased “uncommitted” or _______ of the cortex. They integrate and form connections between sensory and motor areas

Frontal Lobe

Deals with planning, maintaining emotional control and abstract thought.

Weighing future consequences

Develops into the mid 20’s

Broca’s Area

In frontal cortex

Responsible for the production of language

Broca’s Aphasia

Destruction leads to difficulty producing language

Motor Cortex

In frontal lobe

planning, control, and execution of voluntary movements

Parietal Lobes

Located at the top of our head.

Contains the somatosensory cortex (processes touch, temperature, taste (helps))

Rest are association areas (intelligence!)

Occipital Lobes

n the back of our head.

Handles visual input from eyes.

Right half of each retina goes to left occipital lobe and vice versa.

Temporal Lobes

Process sound sensed by ears.

Not cross-wired.

Wernicke’s area

understanding language

Wernicke’s Aphasia

impairment of language understanding

Meaningless spoken language

Reticular Formation

network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum

Help to maintain arousal and consciousness

Brain Plasticity

bility of our brains to form new connections (repair itself) after being damaged

the younger you are, the more “plastic” your brain is

Neurogenesis

Contrary to popular belief, we do grow new nerve cells

Mostly in the hippocampus

Hemispheres

Divided into a left and right hemisphere.

Contralateral controlled- left controls right side of body and vice versa.

Brain Lateralization

some neural functions, or cognitive processes tend to be more dominant in one hemisphere than the other.

Corpus Callosum

Attaches the two hemispheres of cerebral cortex.

Allows both sides to communicate

Split-Brain Patients

When the corpus callosum is removed (usually b/c of seizures)

Roger Sperry & Michael Gazzaniga

Non-Split Brains

People with intact brains also show left-right hemispheric differences in mental abilities

normal individuals tend to engage their right brain when they engage in a perceptual task, and left brain when carrying out a linguistic task

Ways to Study the Brain

Case Studies / Clinical Observation

-Accidents (i.e. – Phinneas Gage)

-Diseases / Disorders

Less Invasive Methods

Electroencephalogram (EEG)

Computerized Axial Tomography (CAT Scan / CT Scan)

Magnetic Resonance Imaging (MRI)

Positron Emission Tomography (PET)

Functional MRI (fMRI)

Electroencephalogram (EEG)

Detects brain waves through their electrical output

Used mainly in sleep research

Computerized Axial Tomography (CAT Scan/CT Scan)

3D x-ray of the brain

good for tumor locating

tells us nothing about function

Magnetic Resonance Imaging (MRI)

More detailed picture of the brain using magnetic field to knock electrons off axis

Takes many still pictures and turns images into a movie like production

Positron Emission Tomography (PET)

measures how much of a chemical the brain is using (radioactive glucose consumption)

Functional MRI (fMRI)

Combination of PET and MRI

It measures the change in blood oxygen to measure brain activity. When part of the brain is working, oxygenated blood rushes to the area

The Endocrine System

a system of glands that secrete hormones into the bloodstream

controlled by the hypothalamus

similar to nervous system, except hormones work a lot slower than neurotransmitters

the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands

Hormones

chemicals synthesized by the endocrine glands and secreted in the bloodstream

affect the brain many other tissues of the body

Pituitary Gland

“master gland”

Anterior pituitary lobe

Releases hormones that regulate other glands

Posterior pituitary lobe

regulates water and salt balance

Evolutionary Psychology

Understanding Human Nature

why we as humans are alike. In particular it studies the evolution of behavior and mind using principles of natural selection.

Behavior Geneticists

study our differences and weigh the relative effects of heredity and environment

Twin Biology

To study the effects of heredity and environment two sets of twins, identical and fraternal, have come in handy

Twin and Procedures

Behavior geneticists study the effects of shared and unique environments on total or partial genetic makeup

Separated Twins

A number of studies have looked at identical twins raised separately from birth or close there after and have found a number of similarities

researchers point out that differences between fraternal twins are greater than identical twins.

Adoption Studies

suggest that adoptees (who may be biologically unrelated) tend to be different from their adoptive parents and siblings

Parenting

does have an effect on biologically related and unrelated children.

Heritability

refers to the extent to which the differences among people are attributable to genes

Nature and Nurture

Some human traits are fixed, like having two eyes, most psychological traits are liable to change with environmental experience.

So genes provide choices to the organism to change its form or traits when environmental variables change. Therefore genes are pliable or self-regulating

Gene-Environment Interaction

Genes ca influence traits which affect responses, and environment can affect gene activity

Molecular Genetics

branch extension of behavior genetics that asks the question, do genes influence behavior

trying to identify genes that put people at risk for disorders

studies why we as organisms are distinct.

Natural Selection

evolutionary process through which adaptive traits are passed on to ongoing generations because they lead animals to reproduce and survive

Artificial Selection

Any trait that is favored naturally or artificially

spreads to future generations