SURVEY OF MODERN PSYCHOLOGY

The Brain

We will discuss:

The parts of the brain and what they do Neurotransmitters The effects of various drugs on the brain

and neurotransmitters

Some general notes about the brain Bilaterally symmetrical along the

longitudinal fissure The left and right side communicate

via the corpus callosum Contra lateral control – the left side

of the brain controls the right side of the body and vice versa

The parts of the brain

Going from the back of the brain towards the front, functions are more advanced

Hindbrain Midbrain Forebrain

Hindbrain

Hindbrain

Cerebellum Balance

Damage (permanent or chemical) causes a wide staggering gait Performance and timing of skilled movements

Damage here causes tremors during movement and an inability to perform rapidly alternating movements

Ex. This would interfere with a skill such as typing Pons

Regulating the brain’s level of attentiveness Initiating sleep and dreaming Integrates movements of and sensations from the facial muscles,

eyes, tongue, and ears Medulla

Controls basic biological functions Cardiovascular and respiratory systems Reflexes (e.g. coughing, swallowing, sneezing) Maintains balance by controlling head orientation and limb

positions with respect to gravity)

Midbrain (Mesencephalon)

Midbrain (Mesencephalon)

•Includes the Tectum and Tegmentum•Tracking moving stimuli (visual and auditory)•Controls eye movements•Coordinates simple movements (controlled by the hindbrain) to form more complicated wholes•Damage here makes the organism unable to perform purposeful behaviors

•E.g., an animal can move and chew, but will not initiate a search for food when it is starving

Forebrain

Forebrain

Parts: Cerebral cortex Limbic system Thalamus Hypothalamus

Forebrain Thalamus

Receives sensory information and conveys it to the relevant structures E.g., vision and other senses, balancing information for movement

Hypothalamus Controls the autonomic nervous system, endocrine system, and major biological

drives

Basal ganglia Control of movement Damage/degeneration here causes Parkinson’s disease

Weakness, tremors, rigidity of limbs, poor balance, difficulty in initiating movements

Includes the hippocampus and amygdala Learning Memory Storing new information into long term memory Some regions are involved in emotions – feeling and expressing emotion,

emotional memories, and recognition of signs of other people’s emotions Stimulation generally produces feelings of anxiety and/or rage

Cerebral Cortex

Frontal lobe

Parietal lobe

Temporal lobe

Occipital lobe

Cerebral Cortex

Frontal lobe Memory, strategy formation, response inhibition Conscious thought

Parietal lobe Senses (touch, pain, temperature)

Temporal lobe Hearing

Occipital lobe Vision

The frontal lobe is largely linked to personality

Much of what we know comes from instances of brain damage or injury

Phineas GageIn an accident in the mid 1800s, a large

steel rod went through his headHe survived, but friends said that there

were major changes in his personality and was “no longer Gage”

In general, injury to the frontal lobe results in: Lack of spontaneity Few facial expressions and gestures Limited and non-fluent speech Strategy formation Lack of response inhibition

The person does not understand rules and therefore has difficulty following rules

•The Hemispheres

•There is a lot of popular theory/cultural belief that the left and right hemispheres serve vastly different functions. •In reality, both hemispheres do play some part in almost all areas.•Most likely, one side is simply more effective and efficient in performing specific tasks.•The division of labor is described as seen in right handed people.

Visual System

Auditory System

Left Hemisphere Language related

sounds

Right Hemisphere• Non-language,

environmental sounds

• Music

Somatosensory System

Left Hemisphere Unknown

Right Hemisphere• Tactile

recognition of complex patterns• E.g., Braille

Movement

Left Hemisphere Complex voluntary

movement

Right Hemisphere• Movements in

spatial patterns

Memory

Left Hemisphere Verbal memory

Right Hemisphere• Nonverbal

memory

Language

Left Hemisphere Speech Reading Writing Arithmetic

Right Hemisphere• Prosody • Narrative• Inference

Spatial Processes

Left Hemisphere Unknown

Right Hemisphere• Geometry• Sense of

direction• Mental rotation

of shapes

Final Notes on Hemispheres

The left and right hemispheres are joined by the corpus callosum.In some severe cases of epilepsy, surgery is performed to cut the corpus callosum.

1981: the Nobel Prize was given to Roger Sperry for his research on “split brains”A participant was prevented from seeing the object and given a pencil in their left hand

The nerve impulse therefore reached the right hemisphere, but not the leftThe participant could generally demonstrate what the pencil should be used for with motions, but could not name the objectThey could only name the object if it was placed in the right hand.

When shown a stimulus is shown on the right side (processed by the left hemisphere) such as words, it is processed faster than if the same was shown on the left side. The right hemisphere needs to send the image to the left side for processing.

Brain Damage

Apraxia Disturbances in movement Lesions in the frontal lobe; disconnect in

primary and nonprimary motor areas Disturbances in initiation or organization of

voluntary actions Ex. Unable to wave Ex. When trying to bake, a person might try to

repeatedly break the same egg, or put a measuring spoon in a bowl as well as the ingredient

Brain Damage

Agnosia Inability to identify familiar objects using a

particular sense Visual agnosia – able to identify a car key by

touch, but not by appearance Able to recognize parts but not a whole

Prosopognosia – inability to identify faces This might be the inability to recognize a

face as a face

Brain Damage

Aphasia Disturbances in language Caused by damage by lesions, usually in the left

hemisphere Nonfluent aphasia

Inability to produce speech, but comprehending what is said Fluent aphasia

Inability to comprehend what is said Speech is made of filler words, with no information

People who can hear sometimes learn Sign Language to communicate

HOWEVERDeaf people who suffer the same brain damage

experience the same difficulties in communication as hearing people with aphasia

Neurons

Parts of a neuron: Dendrites

Receive impulses from other neurons

Cell body Axon Synapse (the space between

cells)

Communication occurs across synapses via neurotransmitters Neurotransmitters are usually

ejected, brought back into axons, and then reused

Lock and key model: the transmitter will only have an effect if it fits into the receptor molecules

Neurotransmitters

The ones we will discuss are: Dopamine Serotonin Norepinephrine Acetylcholine GABA Glutamate Endorphins

Dopamine

Normal function Produces sensations of pleasure and reward Used by the central nervous system (CNS)

neurons involved in voluntary movement Problems associated with imbalance

Schizophrenia Parkinson’s disease

Substances that affect the action of this neurotransmitter Cocaine Amphetamine Alcohol

Serotonin

Normal function Regulates sleep and dreaming, mood, pain,

aggression, appetite, and sexual behavior Problems associated with imbalance

Depression Some anxiety disorders Obsessive compulsive disorder

Substances that affect the action of this neurotransmitter Hallucinogenics

Norepinephrine

Normal function Used by neurons in the automatic nervous system

and by neurons in almost every region of the brain Controls heart rate, sleep, stress, sexual

responsiveness, vigilance, and appetite Problems associated with imbalance

High blood pressure Depression

Substances that affect the action of this neurotransmitter Tricyclic antidepressants Beta blockers

Acetylcholine

Normal function The primary neurotransmitter used by neurons

carrying messages form the CNS Involved in some kinds of learning and memory

Problems associated with imbalance Some muscular disorders Alzheimer’s disease

Substances that affect the action of this neurotransmitter Nicotine Black widow spider venom Botulism toxin

GABA

Normal function The most prevalent inhibitory neurotransmitter

in neurons of the CNS Problems associated with imbalance

Anxiety Epilepsy

Substances that affect the action of this neurotransmitter Barbiturates “Minor” tranquilizers (ex. valium) Alcohol

Glutamate

Normal function The primary excitatory neurotransmitter in

the CNS Involved in learning and memory

Problems associated with imbalance Release of excessive glutamate causes brain

damage after strokes Substances that affect the action of this

neurotransmitter PCP (angel dust)

Endorphins

Normal function Pleasurable sensations Control of pain

Problems associated with imbalance Lowered levels resulting from opiate addiction

Substances that affect the action of this neurotransmitter Opiates (opium, heroin, morphine, methadone)

Drugs

Drugs act on synapses (the spaces between neurons) and affect the response to neurotransmitters

Agonists facilitate effects Antagonists inhibit effects Dependence and addiction are

characterized by tolerance and withdrawal

Drugs

Physical vs. psychological dependence Physical addiction is often defined by the

physiological effects that happen when a person stops using a drug

Psychological dependence involves the emotional feeling of wanting the drug either to produce pleasure or avoid discomfort Psychological addiction tends to be more difficult to

overcome than physical addiction

Positive reinforcement – if it feels good, keep doing it! Withdrawal is the opposite of whatever the effects of

the drug are (E.g., withdrawal from an opiate causes agitation)

Types of Drugs and their Effects Opiates Stimulants Nicotine Alcohol and Barbiturates Cannabis/THC

Opiates

Naturally occurring opiates in the brain block pain

Cause analgesia, hypothermia, sedation, reinforcement

Act on GABA and dopamine Opiate blockers may be used to treat

addiction (no effect, therefore no reinforcement)

Stimulants

Dopamine agonists Stimulate the release of dopamine and

inhibit the reuptake Euphoric, active, and talkative

Hallucinations, paranoia, mood disturbances, repetitive behavior

Similar to schizophrenia

Nicotine

Dopamine and acetylcholine agonists Often harder to quit than “hard” drugs Withdrawal includes anxiety,

restlessness, insomnia, inability to concentrate

Nicotine antagonists can also reduce cocaine cravings

Alcohol and Barbiturates

Dopamine and GABA agonists Small doses produce mild euphoria and inhibits anxiety –

stops the punishing effects of aversive stimuli Ex. if an animal is given shocks when it performs a particular

action, it will stop. If given alcohol, it will not learn and keeps performing the response

Alcohol: Withdrawal can be fatal

Convulsions and seizures Chronic alcoholism can lead to Korsakoff’s Syndrome

This is caused by a vitamin deficiency – frequent alcohol use can block the absorption of some vitamins

Permanent anterograde amnesia (inability to form new memories, but still having old ones)

Confabulation – making up memories Can have elements of reality or be completely imaginary

Cannabis/THC

Cannabis: Dopamine agonist Particularly affects the hippocampus,

causing memory problems Long term use can cause inattentiveness,

impaired memory, reduced ability to multitask