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The Neuron. Pathways to the Nervous System. The Neuron. before birth Approximately upon birth 90% of your cells are glia cells (in CNS) and Schwann cells (in PNS) (fun fact: prenatal neurons develop at the rate of 250,000/minute!!).

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The Neuron

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The neuron

The Neuron

Pathways to the Nervous System

The neuron1

The Neuron

  • before birth

  • Approximately upon birth

  • 90% of your cells are glia cells (in CNS) and Schwann cells (in PNS)

  • (fun fact: prenatal neurons develop at the rate of 250,000/minute!!)

The neuron

Nerve fibers are long dendrites and axons bundled together. They are called nerves in the PNS and tracts in the CNS

Nerves that lead to the brain are also known as:

Nerves going from the brain are:






nissl substance


myelin sheath

nodes of Ranvier terminal feet

terminal buttons


The neuron

Chemicals contained in the terminal buttons are called neurotransmitters, which will leave:

The area between neurons is known as:

All or none law

The all-or-none law states that when a neuron is stimulated, it must stimulated to:

All-or-none law

Ways of measuring the brain

Ways of Measuring the Brain



Used in sleep research, detects dreams and sleep disorders

Ways of measuring the brain1

Ways of Measuring the Brain


Intentional damage to brain cells:

Lesioning has taught us a lot about the functions of the brain

Ways to measure the brain

CT-Computerized Tomography

Horizontal slices:

Least expensive – widely used

Ways to Measure the Brain

Ways to measure the brain1

Positron Emission Tomography (PET)

Radioactive tracer

Color coded map

Ways to Measure the Brain

Ways to measure the brain2

Magnetic Resonance Imaging (MRI)

What it is:

Very expensive

Ways to Measure the Brain

Ways of measuring the brain2

Ways of Measuring the Brain

Electrical Stimulation of the Brain (ESB)

Sends a weak:

Stimulates areas of the brain to determine what effect the stimulation has

Discovered by Penfield, done:

The neuron


Acetylcholine ach


Involved in voluntary movements

Contributes to:

Lack of Ach –

Low levels of Ach – cells die



Hippocampus of the brain

Overabundance of Ach-

Curare-a poison that blocks the transmission of Ach, which will lead to intense spasms of the muscles, including heart –

Dopamine da

Controls voluntary muscles

A monoamine

Lack of –

Too much –




Tardive Dyskenesia-a disease which can cause Parkinson’s-like tremors. This occurs when a person takes meds for:

Plays a major role in addiction as it is similar to adrenaline and controls:

Serotonin se

Highly implicated in

, hence your SSRI’s (antidepressants)

Low levels of SE seemed to be linked to:

Involved in wakefulness and:

A Monoamine


Norepinephrine ne


Low levels of NE have been associated with:

Cocaine and amphetamines may stimulate the activity of this neurotransmitter (may cause hallucinations)

A monoamine


Synthesized by the:

Activates the sympathetic nervous system and puts the body:



Resemble opiates

Pain blockers

Gate control theory:


The neuron

Low levels:

Antianxiety drugs:


Central and peripheral nervous systems

Central Nervous System –

Consists of the:

Central and Peripheral Nervous Systems

Peripheral nervous system


Somatic Nervous System:

Autonomic Nervous System:

Sympathetic NS

Peripheral Nervous System

Peripheral nervous system1


Rest and digest response

Brings the system back to:

Peripheral Nervous System

The brain

Did you know that the brain weighs only about 1 pound at birth?

By one year of age, the brain will double in size and be almost 90% of its adult size

The Brain

Lobes of the brain


Located in front of the central sulcus.

Concerned with:

Lobes of the Brain

Lobes of the brain1

Frontal Lobe-

On the left side is Broca’s area –

Lobes of the Brain

Motor strip

Motor Strip

Phineas gage

After Gage had an accident in which a metal pipe went through his brain, it was thought that he would not survive.

However, he did – with interesting consequences

Phineas Gage

Lobes of the brain2


Located behind the central sulcus.

Concerned with:

Lobes of the brain

The neuron

The Primary Somatosensory Cortex

Neurons in the primary somatosensory are activated when the skin is touched. However, the body is NOT represented in the cortex in proportion to the amount of skin.

The neuron

A map of the human somatosensory cortex was drawn by Dr. Wilder Penfield in the 1950's.

By observing the location on the brain that caused patients to feel sensations on different parts of their bodies, Dr. Penfield was able to draw a map of the brain

Lobes of the brain3


Located below the lateral fissure.

Concerned with:

Lobes of the Brain

Lobes of the brain4

Temporal Lobe –

Behind the temporal lobe is the uncus –

Left side of temporal lobe is Wernicke’s area -

Lobes of the Brain

Lobes of the brain5


Located at the back of the brain, behind the parietal lobe and temporal lobe.

Concerned with:

Lobes of the Brain

The lobes of the brain


The Lobes of the Brain

Medial view sensory motor areas

Medial View Sensory & Motor Areas

The brain1

Brain Weight(gm)





Adult Human


Rhesus Monkey









The Brain

How does the human brain compare

How does the human brain compare?

Parts of the brain

Cerebral cortex functions:


Voluntary movement




Parts of the Brain

The hindbrain



Looks like a mini-brain

The Hindbrain



  • Two peach-size mounds of folded tissue at the base of the brain form the cerebellum.

  • Damage to this area leads to:

  • Some scientists have discovered:

The hindbrain1


Control of:

a.k.a. the medulla oblongata

The Hindbrain

The hindbrain2


Located above the medulla

Connects midbrain with the:


Contains sensory and motor tracts between the cortex and the medulla

Involved in:

The Hindbrain

The midbrain

The midbrain is very small in humans

Coordinates simple movements with sensory information

The Midbrain

The midbrain1

Reticular formation (a.k.a. Reticular activating system)

Attention and arousal-

If damaged, the person may:

Involved in pain perception

The Midbrain

The forebrain


Functions as a relay station – sends sensory information to:

The only sensory information that does not travel through the thalamus is:

The Forebrain

The forebrain1


Known for four F’s-

Although the pituitary gland is given credit for regulating the endocrine system, it is the hypothalamus that sends the message to:

The Forebrain

The forebrain2



Controls your biological rhythms, so it is also involved with whether you are a morning person or an afternoon person

The Forebrain

The forebrain3

Limbic system:

Regulation of emotions-

Also known for being involved with:

Hippocampus, amygdala, septum, part of the thalamus and hypothalamus

The Forebrain

The forebrain4


The Forebrain

  • Involved in memory and how we:

  • Removal of temporal lobe can result in:

The forebrain5


Many memories are not stored there, however, the hippocampus sends information to different areas of the cerebral cortex for processing

The Forebrain

The forebrain6


Plays a role in aggression and defensiveness

When damaged:

When stimulated:

The Forebrain

The forebrain7


Important pleasure center of the brain – mild stimulation of this area may result in intense pleasurable feelings, including intense sexual arousal

Lesions to the septal area may result in:

Stimulation results in:

The Forebrain

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Corpus callosum

The brain has identical parts in each hemisphere

The corpus callosum connects:

Often cut in patients with:

Corpus Callosum


Largest part of the brain

Divided into two hemispheres – each hemisphere has identical parts:

Separate by the-

Divided into four lobes


Hemispheres of the brain

Hemispheres of the Brain

  • Are you right-handed or left-handed?

  • About 90% of the population are right-handed - they prefer to use their right hand to write, eat and throw a ball ("right hand dominant.“)

  • Most of the other 10% of the population is left-handed or "left hand dominant."

  • There are few people who use each hand equally; they are "ambidextrous.”



Marion diamond

Demonstrated that an enriched environment will increase cell weight and add to the number of dendrites on the neuron

An impoverished environment decreases cell weight:

Marion Diamond

Environmental impact on the brain

From the time a baby is born (and possibly before) they are beginning the formation of trillions of neuronal connections via the environment

Neurons will constantly grow, die, become stronger or weaker depending on the environment

Environmental impact on the brain..

Emotions and learning

Positive emotions, however, can enhance learning

When students laugh or have positive feelings towards learning they are more likely to learn

Emotions and learning

The adolescent brain

“What were you thinking?”

“Don’t you ever think before you act?”

“When are you going to make better decisions?”

“How many times do I have to say the same thing over and over again?”

Any of this sound familiar?

The Adolescent Brain

The adolescent brain1

The prefrontal cortex has not fully developed and the thinking, judging, planning portion of their brain is not functioning to its fullest capacity

The Adolescent Brain

The adolescent brain2

New research indicates that the adolescent brain has new cell growth and new neural connections

This new growth and the pruning of neurons not in use help the brain develop emotional maturity

The Adolescent Brain

Diseases of the brain

Alzheimer’s Disease

have gradual memory loss and difficulty with language and emotion

while the disease starts out slowly, it progresses to the point that the person needs help eating, bathing and using the bathroom

Diseases of the brain

Diseases of the brain1

Scans may help in the diagnosis

CAT scans tend to help visualize brain shrinkage and enlarged ventricles

Diseases of the brain

Diseases of the brain2

Research has demonstrated that the more neuronal connections one has, the more likely they are to lessen the effects of AD

Therefore, one should keep active physically and mentally

Diseases of the brain

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