PSY 2012 Chapter 3 Neuroscience & Behavior

Behavioral Neuroscientist

psychologists who specialize in considering the ways in which the biological structures and functions of the body affect behavior.

Questions that behavior neuroscientist seek to answer

• how does the brain communicate with other parts of the body

• how does the brain communicate with other parts of the body

• what is the physical structure of the brain, and how does this structure affect behavior

Nervous System

the pathway for the instructions that permit our bodies to carry out activities

How do we perform complex movements for physical activities?

the brain send messages through specialized cells called neurons

Neurons

nerve cells; the basic elements of the nervous system

Neurons consist of

a cell body that contains a nucleus

Neurons are held in place by

glial cells

Glial cells

• Provide nourishment to neurons

• Insulate neurons

• Help repair damage

• Support neural functioning

Distinct factors of neurons

• the ability to communicate with other cells

• can transmission of information across relatively long distances

Parts of the Neuron

• dendrite

• axon

• terminal buttons

• myelin sheath

Dendrites

cluster of fibers at one end of a neuron that receives messages from other neurons

Axon

part of the neuron that carries messages destined for other neurons

Terminal Button

small bulges at the end of axons that send messages to other neurons

Myelin Sheath

• protective coat of fat and protein that wraps around the axon

• prevents messages from short-circuiting

• serves to increase the velocity with which electrical impulses travel through axons

The messages that travel through a neuron are

electrical

Impulses

• electrical messages

• generally move across neurons in one direction

route of impulses

dendrites → cell body → along the tube-like extension → axon → adjacent neuron

All-or-Nothing law

neurons are either on or off with nothing in between

Resting state

• state in which there is a negative electrical charge of about −70 millivolts within a neuron

• before a neuron is triggered

How is a resting state caused?

the presence of more negative charged ions within the neuron than outside it

Action Potential

Electric nerve impulse that travels through a neuron’s axon when it is set off by a “trigger”

Positive electrical charge of about how much within a neuron?

about +40 millivolts

as the impulses travels along the axon, the movement of ions causes a change in charge from

negative to positive

after the impulses passes through a particular section of the axon, the charge becomes

positive to negative

Speed at which an action potential travels along an axon is determined by

• the axon’s size

• the thickness of the myelin sheath

Neurons differ in terms of

• quickness of an impulse moving along the axon

• potential rate of firing

Intensity of a stimulus determines

how much of a neuron’s potential firing rate is reached

Mirror Neurons

specialized neurons that fire, when a person:

• enacts a particular behavior

• observes another individual carrying out the same behavior

Why was discovering mirror neurons a great thing

they could help explain how an why humans’ capacity to imitate others may be an inborn behavior

Synapse

space between 2 neurons where the axon of a sending neuron communicates with the dendrites of a receiving neuron by using chemical messages

What happens when a neuron impulse reaches the end of the axon and reaches a terminal button

the terminal button releases a neurotransmitter

Neurotransmitter

Chemicals that carry messages across the synapse to the dendrite (and sometimes the cell body) of a receiving neuron

Successful chemical communication is possible only when

a neurotransmitter fits precisely into a receptor site

If a neurotransmission does fit into a site on the receiving neuron, the chemical message it delivers is either:

• excitatory message

• inhibitory message

Excitatory message

Makes it more likely that a receiving neuron will fire and an action potential will travel down its axon

Inhibitory message

Prevents or decreases the likelihood that a receiving neuron will fire

If neurotransmitters remained at the site of the synapse, it would lead to

• receiving neurons awash, in a continual chemical bath

• producing constant stimulation or constant inhibition of the receiving neurons

• effective communication across the synapse would no longer be possible

How do we avoid issue with a neurotransmitters remaining at the site of the synapse

• enzymes deactivate the neurotransmitters

• more commonly, the terminal button sucks them back in

Reuptake

the reabsorption of neurotransmitters by a terminal button

Why is it important to understand reuptakes?

it has led to the development of certain drugs that treat psychological disorders such as SSRIs

SSRIs

• selective serotonin reuptake inhibitors

• permit certain neurotransmitters to remain in synapses for a longer period of time

• reduces symptoms of depression

Names of Neurotransmitters

• acetylcholine (ACh)

• glutamate

• gamma-amino butyric (GABA)

• dopamine (DA)

• serotonin

• endorphins

Locations of the Acetylcholine (ACh)

• brain

• spinal cord

• peripheral nervous system

• some organs of the parasympathetic nervous system

Locations of the Glutamate

• brain

• spinal cord

Locations of the Gamma-Amino Butyric Acid (GABA)

• brain

• spinal cord

Locations of the Dopamine (DA)

• brain

Locations of the Serotonin

• brain

• spinal cord

Locations of the Endorphins

• brain

• spinal cord

Effects of the ACh neurotransmitters

• excitatory in brain and autonomic nervous system

• inhibitory elsewhere

Effects of the Glutamate neurotransmitters

• excitatory

Effects of the GABA neurotransmitters

• main inhibitory neurotransmitter

Effects of the DA neurotransmitters

• inhibitory or excitatory

Effects of the Serotonin neurotransmitters

• inhibitory

Effects of the Endorphins neurotransmitters

• primary inhibitory

• except in hippocampus

Functions of the ACh neurotransmitters

• muscle movement

• cognitive function

Functions of the Glutamate neurotransmitters

• memory

Functions of the GABA neurotransmitters

• eating

• aggression

• sleeping

Functions of the DA neurotransmitters

• movement control

• pleasure and reward

• attention

Functions of the Serotonin neurotransmitters

• sleeping

• eating

• mood

• pain

• depression

Functions of the Endorphins neurotransmitters

• pain suppression

• pleasurable feeling

• appetites

• placebos

Each neuron can connected to how many other neurons?

80,000 neurons

2 main parts of the nervous system

• central nervous system

• peripheral nervous system

Central Nervous System

part of the nervous system that includes the brain and spinal cord

Spinal Cord

• bundle of neurons that leaves the brain and runs down the length of the back

• main means for transmitting messages between the brain and the body

• controls simple behaviors on its own, without any help from the brain

Relfix

automatic, involuntary response to an incoming stimulus

Kinds of Neurons involved in reflexes

• Sensory Neurons

• Motor Neurons

Sensory (afferent) neurons

transmit information from the perimeter of the body to the central nervous system

Motor (efferent) neurons

communicate information from the nervous system to muscles and glands

Quadriplegia

a condition in which people loose voluntary muscle movements below the neck

Paraplegia

a condition in which people are unable to voluntarily move any muscles in the lower half of the body

Peripheral Nervous System

made up of neurons with long axons and dendrites, it branches out from the spinal cord and brain and reaches the extremities of the body

The peripheral Nervous System includes

• somatic division

• autonomic division

Somatic Division

specializes in the control of voluntary movements and the communication of information to and from the sense organs

Autonomic Division

controls involuntary movement of the heart, glands, lungs, and other organs

Autonomic nervous system consists of

• sympathetic division

• parasympathetic division

Sympathetic division

acts to prepare the body for action in stressful situations, engaging all the organism’s resources to respond to a threat

Parasympathetic division

Acts to calm the body after an emergency has ended

Hierarchically Organized

relatively newer (from an evolutionary point of view) and more sophisticated regions of the brain regulate the older, and more primitive, parts of the nervous system

Evolutionary Psychology

branch of psychology that seeks to identify behavior patterns that are a result of our genetic inheritance from our ancestors

Behavioral Genetics

study of the effects of heredity on behavior

Endocrine system

a chemical communication network that sends messages throughout the body via the bloodstream

Hormones

chemicals that circulate through the blood and regulate the functioning or growth of the body

Pituitary Gland

major component of the endocrine system, or the “master gland”

Despite the Pituitary Gland being designated the “master gland“, why is it considered the servant of the brain?

the brain is ultimately responsible for the endocrine system’s functioning

Electroencephalogram (EEG)

records electrical activity in the brain through electrodes placed on the outside of the skull

Functional magnetic resonance imaging (fMRI)

provides a detailed, three-dimensional computer-generated image of brain structures and activity by aiming a powerful magnetic field at the body

Positron emission tomography (PET)

• shows biochemical activity within the brain at a given moment

• requires radioactive tracer injection

Transcranial magnetic stimulation (TMS)

• causes a momentary interruption of electrical activity by exposing a tiny region of the brain to a strong magnetic field

Central Core

• the old brain

• controls basic functions such as eating and sleeping and is common to all vertebrates

Hindbrain

contains the:

• Medulla

• Pons

• Cerebellum

Hypothalamus

• tiny part of the brain, located below the thalamus

• maintains homeostasis

• produces and regulates behavior that is critical to the basic survival of the species

Pons

• bridge in the hindbrain

• acts as a transmitter of motor information

• involved in regulating sleep

Reticular Formation

• extends from the medulla through the pons, passing through the midbrain and the forebrain

• produces general arousal of the body

Cerebral Cortex

• the “new brain“

• responsible for the most sophisticated information processing in the brain

Corpus Callosum

• the bridge of fibers passing information between the two cerebral hemisphere

Thalamus

• part of the brain located in the middle of the central core

• relays information about the senses

• handles incoming and outgoing signals

Cerebellum

• controls bodily balance

Medulla

• controls a critical body functions, such as breathing and heartbeat

Limbic System

• part of the brain that controls eating, aggression, and reproduction

• plays an important role in emotion, learning, and memory, along with hippocampus

the Limbic System includes

• the amygdala

• the hippocampus