Biological Psychology Biological Roots of Behavior How the Brain Governs Behavior Neurotransmitters

Biological Psychology

Biological Roots of BehaviorHow the Brain Governs Behavior

Neurotransmitters

“So why do we have to study biology in a psych class?”

• Let me use Phineas Gage to help answer this question…

“He was no longer Gage…”

• Several different angles of where the rod passed through his skull

There is a Phineas Gage display in the Warren Medical Museum at Harvard University

• This is what went through his brain (see below)…

Biological Roots of Behavior

• Franz Gall (1758-1828) – Austrian physicist who invented phrenology

• He felt that bumps on the skull could reveal our mental abilities and character traits.

• Introduced as being scientific but its use was exploited by quacks on gullible individuals

Biological Roots of Behavior

• Became similar to that of astrology, palm-reading and tarot

• Although, ill-fated theory was laughed at by scientific community of that day – it may have had some validity

• Localization of brain functions somehow hit the mark

The Nervous System

• Electrochemical communication system that enables us to think, feel, and behave.

• Complex beyond comprehension• Although, human brains are more

complex our nervous systems and those of animals operate in a similar fashion – advantage of this is experimentation

The Nervous System

• Allows researchers to study simple animals such as squids and sea slugs to help us better understand the organization of our own brains

Divisions of the Nervous System

• Consists of two systems– Central Nervous System

• Brain and spinal cord– Peripheral Nervous System

• Which connects the CNS to the rest of the body

Organization of the Nervous SystemOrganization of the Nervous System

Peripheral Nervous System

• Two components: – Somatic Nervous System

• Transmits sensory input to the CNS from the outside world and directs motor output

– Autonomic Nervous System• Controls glands and muscles of our

internal organs – “automatic pilot”

Autonomic Nervous System

• Dual system:– Sympathetic Nervous System

• Arouses the body– Parasympathetic Nervous System

• Calms us down

Neurons

• Nerve cells (building blocks) – essentially identical to animals – Small samples of brain tissue from a person

and a monkey are basically indistinguishable

Endocrine System: Taking the slow lane

• Unlike the speedy nervous system which zips messages from eyes to brain to hand in a fraction of a second, endocrine messages use the slow lane

• May take several seconds or more as bloodstream carries a hormone from an endocrine gland to its target tissue

Endocrine System

• Hormones are chemical messengers

• Influence all aspects of our lives – growth, metabolism, reproduction, moods, etc.

• Strives for homeostasis (balance) by responding to stress, exertion, internal thoughts, etc.

The Brain

• Studying the brain:– Clinical observations– Manipulating the brain

How does the brain govern behavior?

• 3 Principle layers of the brain: (1) Brainstem (2) Limbic System

• Hippocampus• Amygdala• Hypothalamus

(3) Cerebral Cortex

The Whole Brain Atlas

What the Brain Controls

The Lobes of the Brain

A Positron Emission Tomography Scanner (PET)

So we can understand how people get……..

Murderous mind? A PET scan reveals less activity in the prefrontal cortex of a convicted killer (right)than in that of a nonviolent control.

A Pet Scan of a Depressed Patient

A PET Scan of a Schizophrenic Patient

Brainstem (or Hindbrain)

• The brain’s innermost region…– Begins where the spinal cord enters the

skull and swells slightly forming the medulla

– Towards the rear of the brainstem is the cerebellum – this is linked to memory and its major function is muscular control

Limbic System

• Hippocampus – This structure plays a key role in allowing

us to store new information– Problems here may cause Alzheimer's –

these individuals have trouble processing declarative memories

– Milner (1968): the classic case of H.M.

Limbic System

• Amygdala– Emotional control center of the brain –

major influence on aggression and fear– Emotional memories as well– Alzheimer’s ???

• Kluver and Bucy (1939)• Demasio (1994)

Limbic System

• Hypothalamus– Major influence on hunger, thirst, body

temperature, and sexual behavior• Olds and Milner (1954)

Cerebral Cortex

• Makes us distinctively human – much higher developed than in animals– Motor Cortex – involved in the conscious initiation

of voluntary movements in specific parts of the body including hand, knee, foot and head

• Fritsch and Hitzig (1870)• Delgado (1969a)• Delgado (1969b)• Penfield (1975)

Cerebral Cortex

• Sensory Cortex – receives information from our senses– Visual cortex

• visual info– Auditory cortex

• auditory info– Somatosensory cortex

• info from skin• Association cortex

– involved in complex cognitive tasks associating words with images

• Broca’s area (aphasia)• Wernicke’s area (aphasia)

Neurons

More Neurons

And just one more!!

Neurotransmitters

• Neurotransmitters are chemicals made by neurons and used by them to transmit signals to the other neurons

• A chemical message telling the next cell to fire or not to fire its own action potential

• More than 200 in our body all with different functions

• Lets briefly discuss some of the most important ones…

Serotonin

• Facilitates a relaxed, sleepy feeling • Tryptophan which is an amino acid

found in dairy products and turkey is converted into serotonin in the body

• So, insomnia sufferers may be smart to listen to grandmother’s suggestion to drink a warm glass of milk before going to bed

Some Illnesses Associated With Serotonin

• Too low levels in depression and anxiety sufferers

• Obesity may also be associated with low levels

• Linked to aggression as well -- low levels in the brains of suicide victims

Dopamine

• High levels lead to pleasure– Makes person feel happy and active

• Dopamine raises the body's temperature and increases metabolic rate

• Gives you euphoric feelings and allows you to be active

• Drug and alcohol abuse will block dopamine receptors and therefore a person needs to take more to get the same effect

Illnesses Associated With Dopamine

• Parkinson’s Disease – too low levels

• Schizophrenia – too high levels

• Tourette’s disorder – too high levels

• Huntington’s disease – too high levels

Norepinephrine

• Plays a role in attention and arousal

• Used by sympathetic nervous system to prepare us for action

Illnesses Associated With Norepinephrine

• Depression – chronic stress depletes this neurotransmitter

and can lead to depression

• Note:– Aerobic Exercise is found to protect the

brain from this depletion – so go out and run a mile or two if your down in the dumps

Epinephrine

• Involved in energy and glucose metabolism

Illnesses Associated With Epinephrine

• Depression – too low levels

Acetylcholine

• Involved in voluntary movement, learning, memory, and sleep

• Helps parasympathetic nervous system to slow our heart rate

Illnesses Associated With Acetylcholine

• Alzheimer’s disease – too low levels

• Note:– Unfortunately, drugs used to increase

acetylcholine to help restore normal levels appear to have small effects on improving memory

GABA

• Inhibits excitation and anxiety

• Appears directly related to anxiety reduction

Illnesses Associated With GABA

• Anxiety disorders – too low levels• Huntington’s Disease – too low levels

– GABA systems aren’t working and this allows dopamine systems to run wild

– Huntington's disease is a hereditary disorder characterized by memory loss, abnormal movement and premature death• It affects 1 in 10,000 people, and children with an

affected parent have a 50 percent chance of developing the disease

• Epilepsy – too low levels

Glutamate

• Main excitatory neurotransmitter in the brain

• Very important in learning and memory

Illnesses Associated With Glutamate

• Alzheimer’s disease – too low levels in hippocampus

• Strokes – too high levels can cause neurons to die

• ALS (Lou Gehrig’s Disease) – causes death in neurons in the spinal cord and brainstem

Endorphins

• Involved in pain reduction and pleasure

• They enhance the release of dopamine

• These natural opiates are released in response to pain and vigorous exercise

Illnesses Associated With Endorphins

• Use of artificial opiates can cause body to stop manufacturing its own – this can lead to drug addiction