PSYCH 104 - Biological Basis of Behaviour

Brain 2

Neurons & Glial cells

Central Nervous System

Peripheran Nervous System

Neurons (Nerve Cells)

Depend on oxygen and glucose constantly.

Glial

AkA Neuriglia, Provide structural, nutritional, and other types of support to brain.

Parts of a Neuron

Soma, Dendrites, Axon, Axon Terminals

Soma

Cell body of neuron. They synthesize macromolecules, integrage electrical signals.

Dendrites

Extensions of cell body, Collects info from other neurons

Axon

Can be short or long. Part of the neuron, and wrapped in myelin (myelin sheath). Conducts information to other neurons.

Myelin Sheath

protects the axon.

Axon Terminals (Presynaptic terminals)

Transmits information to other neurons.

Synaptic Vesicle

Circular sacs containing neurotransmitters.

Neurotransmitter

Chemical released from axon terminal

Synapse

Site where the transmission of synaptic veicles occur.

Synaptic Cleft

Gap where neuro transmitters are released from axon terminal

Unipolar Neuron

One process from the cell body

Bipolar Neuron

Two processes from the soma. Usually for senses.

Multipolar Neuron

Multiple processes coming from the cell body. One axon, but multiple dendrites.

Resting Potential

Difference in electrical charge

Salty Banana

Potassium on the inside, coated in salt on the outside. Inside has negative charge, outside is positively charged.

Resting potential

Difference between inside and outside charge. Typically 70 millivolts

Threshold past resting state is…

-55 millivolts

Depolarization

Reduction of a membranes resting potential so that it becomes less negative. Happens right after a big stimulus.

Action Potential

Travels down the axon of the neuron

Repolarization

Na+ channels close, K+ channels open K+ efflux down electro-chemical gradient

Hyperpolarization

“Overshoot” of Repolarization

Refractory Period

The time during which another action potential is impossible; limits the maximal firing rate of the neuron

Can different stimuli strengths be communicated by neurons?

It can convey the strength of the stimulus

Can neurons transmit faster or slower?

Neuron with thicker axon or more miyelenated will transmit faster

Presynaptic Neuronq

Postsynaptic Neuron

Postsynaptic Potential

Voltage change at a receptor site on a postsynaptic cell membrane

Excitatory PSP

Pushes and increases the likelihood that post synaptic neurons will fire action potentials (further than -55MV)

Inhibitory PSP

Opposite of excitatory PSP, decreases likelihood of neuron firing action potentials.

Reuptake

Reabsorbation of neurotransmitters from the presynaptic cleft to the presynaptic membrane

Patterns of activation

One neuron isn’t responsible for just one thing. We need to rather look at patterns of activation.

Neurons can contain

more than one neurotransmitter

Two Kinds of neurotransmitters

Small and Large Molecule Neurotransmitters

Small-Molecule Neurotransmitters

Amine Acids, Glutamate, Dopamine, Monoamines, Acetylcholine, Unconventional Neurotransmittes (slide 19, see bold ones)

Large-Molecule Neurotransmitters

Neuropeptides, Endorphins

Acetylcholine (ACh)

Released by motor neurons controlling skeletal muscles. Attention, arousal, memory.

How does botox work?

Botox prevents ACh from releasing in the injection site.

Alzheimer’s Disease is associated by

Associated with low levels of ACh

Nicotine

Acts like ACh, stimulates ACh receptors.

Agonist

Mimics action of neurotransmitter

Antagonist

Chemical that blocks the action of a neurotransmitter. Binds with the neurotransmitters receptor site.

Monoamines

Synthesized by tyrosine.

• Dopamine

• Norepinephrine

• Serotonin

Dopamine (DA)

Part of the Monoamines family (micro-molecule)

Contributes to control of voluntary movement. Known to be associated with schizophrenia, and responsible for symptoms of Parkinson’s disease.

Serotonin (5-HT)

Micromolecule in the Monoamine family.

Involved in regulation of sleep and wakefulness, eating, and aggression.

SSRI drugs like Prozac and antidepressant drugs affect serotonin circuits, which puts more serotonin and gives a greater chance for serotonin to bind.

Norepinephrine (NE)

Micromolecule in the momoamine family

Brain arousal and mood, hunger, sleep, and sexual behavior. Different because it also functions like a hormone as well as a neurotransmitter.

AKA Noradrenaline.

What generates fight of flight response?

Norepinephrine (NE). Releases amount of glucose. Reduced bloodflow for gastrointestinal system.

GABA

Amino Acid Micromolecule Neurotransmitter

• Main inhibitory transmitter

• Regulator of anxiety and sleep/arousal

Brain’s main inhibitory transmitter is

GABA

Glutamate

Opposite of GABA, main excitatory neurotransmitter in nervous system. toxic and damaging in large quantities. Why many people believe is bad for you, but it’s unwarranted.

Neurotransmitter that participates in relay of sensory information and learning

Glutamate (Micromolecule, Amino Acid)

Anadamide

Unconventional Neurotransmitters

Binds to same receptorsas THC.

Comes from sanskrit “joy,bliss, delight” “anada”

both central and nervous system.

Plays a role in eating, memory, motivation, and sleep.

Inhibits pain, wounds heal faster, less anxiety (woman that feels no pain)

Lots of Anandamide

CIPA

Rare condition that has no pain.

Neuropeptides

Painkiller,

Endocrine System

Series of glands that produce chemical substances known as hormones

Hormones

“Slow” chemical messenger released in the blood by endocrine glands

Neural Plasticity in Early Development

1. Growth of Dendrites and axons

2. Synaptogenesis

   1. Formation of ne wsynapses

3. Pruning

   1. Removal of extra synapses to increase efficiency

   2. Occurs until about 10

   3. ~70% of neurons die

4. Myelination

   1. Insulation of axons with a myelin sheath

Long-Term Potentiation (LTP) of Synapses

A long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously

Neurons that Fire together…

Wire together

Why do neurons create long term potentiation?

Neurons that fire together wire together.

Neural Plasticity Following Injury

Different brain regions can sometimes take over functions previously performed by others. (Ex. Blind people reading braille, a different part of the brain works differently).

Stem Cell

A cell (often originating in embryos) which has the capacity to differentiate into a specialized cell.

What provides the potential to offer treatments for Alzheimer’s stroke, Parkinson’s, Diabetes, Blidness, Deafness, INfertility?

Stem Cells

Neurogenesis

Creation of new neurons in the adult brain.

Abbreviation for Long Term Potentiation

LTP

Meninges

Three protective membranes that cover the brain and spinal chord.

( Dura Mater, Arachnoid Mater, Pia MAter)

Three Meninges

Dura, Arachnoid, and Pia mater

Thickest of the Meninges

Dura Mater

When will you have the most neurons of your life?

At birth.

Cerebral Ventricles

Pockets in the brain that contain cerebrospinal fluid (CSF) which provide nutrients and cushion to the brain.

Where is CSF found in the meninges?

Subarachnoid Space

Franz Joseph Gall

• All mental functions arise from the brain

• Mind + Body are NOT separate entities (anti- descartes)

• Brain consists of functional regions

Pierre Florens

The brain has distinct functional regions

Cerebral Cortex: Outermost part of forebrain.

Outermost part of the forebrain. Gross, wrinkly bit.

• Left and right Hemispheres

Part of the brain responsible for processing higher brain functions.

Cerebral Cortex

Cerebral Hemispheres

Two halves of the cerebral cortex. Has different functions.

Corpus Callosum

Large band of fibers connecting the two cerebral hemispheres. It’s in the middle.

Frontal Lobe

Performs functions that coordinate other brain areas, motor, language, memory

Primary Motor Cortex

The part of the frontal lobe. Responsible for bodily movement

Penfield (Scientist)

Found that electric shocks specifically to primary motor cortex create bodily movement.

Cortical Homunculus

Weird statue made by Penfield that shows the proportion of how many nerves are directed to each part of the body.

Prefrontal Cortex

Part of frontal lobe responsible of thinking, planning, language

Broca’s Area

Language area in the prefrontal cortex that helps to control speech production and some speech comprehension

Phineas Gage

Rod through his head (frontal lobe), personality changes.

Parietal Lobe

Touch information, integrates vision and touch.

Primary Somatic Sensory Cortex

AKA “somatosensory cortex”. Regions of the cerebral cortex that initially process information from the senses

Somatosensory

Means “bodily sensation”

Temporal Lobe

Processes auditory information language and autobiographical memory

Wernicke’s Area

Part of the temporal lobe involved in understanding speech.

People who talk naturally but they don’t make any sense has damage to what area of the brain?

Wernicke’s Area. (Temporal) AKA Language salad.

The Occipital Lobe

Back part of cerebral cortex for vision.