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