Chapter 2: The Biological Perspective

Nervous System

An extensive network of specialized cells that carries information to and from all parts of the body

Neuroscience

A branch of the life sciences that deals with the structure and function of neurons, nerves, and nervous tissue

Biological Psychology (Behavioral Neuroscience)

Branch of neuroscience that focuses on the biological bases of psychological processes, behavior, and learning

Neuron

The basic cell that makes up the nervous system and that receives and sends messages within that system

* Messengers of the body

Dendrites

Branchlike structures of a neuron that receive messages from other neurons

Soma

The cell body of the neuron responsible for maintaining the life of the cell

* Processes information

Axon

Tubelike structure of neuron that carries the neural message from the cell body to the axon terminals, for communication with other cells

Axon Terminals

Enlarged ends of axonal branches of the neuron, specialized for communication between cells

Glial Cells

Cells that provide support for the neurons to grow on and around, deliver nutrients to neurons, produce myelin to coat axons, clean up waste products and dead neurons, influence information processing, and, during prenatal development, influence the generation of new neurons

• Help maintain homeostasis (sense of balance)

• Increasingly becoming understood as partner cells, not just support cells

• Play important roles in learning, behavior, and neuroplasticity by affecting synaptic connectivity and facilitating communication between neurons in specific neural networks

Myelin

Fatty substances produced by certain glial cells that coat the axons of neurons to insulate, protect, and speed up the neural impulse

Oligodendrocytes

Produce myelin for the neurons in the brain and spinal cord–the central nervous system

Schwann Cells

Produce myelin for the neurons of the body–the peripheral nervous system

Nerves

Bundles of axons coated in myelin that travel together through the body

The balances of ions in and outside of the neuron

What determines relative charge of the neuron?

Negative

Relative charge of ions inside the cell is mostly…

Positive

Relative charge of ions outside the cell is mostly…

Diffusion

Process of molecules moving from areas of high concentration to areas of low concentration

Electrostatic Pressure

The relative balance of electrical charges when the ions are at rest

Resting Potential

The state of the neuron when not firing a neural impulse

Action Potential

The release of the neural impulse, consisting of a reversal of the electrical charge within the axon

* Allows positive sodium ions to enter the cell, causing the inside to be mostly positive

All-or-None

Referring to the fact that a neuron either fires completely or does not fire at all

It causes neurons to fire repeatedly and will cause more neurons to fire

What does a strong message do to neurons?

Synaptic Vesicles

Saclike structures found inside the synaptic knob containing chemicals

Neurotransmitter

Chemical found in the synaptic vesicles that, when released, has an effect on the next cell

Synapse (Synaptic Gap)

Microscopic fluid-filled space between the axon terminal of one cell and the dendrites or soma of the next cell

* Allow information to be sent from one cell to another

Receptor Sites

Three-dimensional proteins on the surface of the dendrites or certain cells of the muscles and glands, which are shaped to fit only certain neurotransmitters

They release their neurotransmitters into the synaptic gap, which float across the synapse and fit themselves into receptor sites (and end up activating the next cell)

What happens when action potential reaches synaptic vesicles?

Excitatory Response

Synapse at which a neurotransmitter causes the receiving cell to fire

Inhibitory Response

Synapse at which a neurotransmitter causes the receiving cell to stop firing

Antagonists

Chemical substances that block or reduce a cell’s response to the action of other chemicals or neurotransmitters

* Ex: Anesthesia is used so you don’t feel pain; it’s blocking pain signals

Agonists

Chemical substances that mimic or enhance the effects of a neurotransmitter on the receptor sites of the next cell, increasing or decreasing the activity of that cell

Acetylcholine (ACh)

Excitatory or inhibitory; involved in arousal, attention, memory, and controls muscle contractions

Norepinephrine (NE):

Mainly excitatory; involved in arousal and mood

Dopamine (DA)

Excitatory or inhibitory; involved in control of movement and sensations of pleasure

Serotonin (5-HT)

Excitatory or inhibitory; involved in sleep, mood, anxiety, and appetite

Gamma-Aminobutyric Acid (GABA)

Major inhibitory neurotransmitter; involved in sleep and inhibits movement

Glutamate

Major excitatory neurotransmitter; involved in learning, memory formation, nervous system development, and synaptic plasticity

Endorphins

Pain-controlling chemicals in the body

Reuptake

Process by which neurotransmitters are taken back into the synaptic vesicles

They block the reuptake process

How do drugs like cocaine affect the nervous system?

Enzyme

Complex protein that is manufactured by cells

Enzymatic Degradation

Process by which the structure of a neurotransmitter is altered so it can no longer act on a receptor

Lesioning

Insertion of a thin, insulated electrode into the brain through which an electrical current is sent, destroying the brain cells at the tip of the wire

• Usually done to an animal and then tested to see what happened to its abilities

• This can’t be done to humans but they can study and test people who already have brain damage

Brain Stimulation

• Temporarily disrupt or enhance the normal functioning of specific brain areas through electrical stimulation and then study the resulting changes in behavior or cognition

• Much milder current than lesioning

Electrical Stimulation of the Brain (ESB)

Milder electrical current that causes neurons react as if they have received a message

Deep Brain Stimulation (DBS)

Neurosurgeons place electrodes in specific deep-brain areas and then route the electrode wires to a pacemaker-like device (impulse generator) that is implanted under the collarbone

* Impulse generator implanted and sends impulses to implanted electrodes, stimulating brain areas of interest

Optogenetics

Neurons are activated by light instead of electricity

Transcranial Magnetic Stimulation (TMS)

Magnetic impulses are applied to the cortex using special copper wire coils positioned over the head

Repetitive TMS (rTMS)

TMS where longer lasting stimulation results when pulses are administered repetitively

Transcranial Direct Current Stimulation (tDCS)

Uses scalp electrodes to pass very low amplitude direct current to the brain to change the excitability of cortical neurons directly below the electrodes

Computed Tomography (CT)

Brain-imaging method using computer-controlled X-rays of the brain

• Can show stroke damage, tumors, injuries, abnormal brain structure, and imaging possible skull fractures

• Can work with metal in the body

Magnetic Resonance Imaging (MRI)

Brain imaging method using radio waves and magnetic fields of the body to produce detailed images of the brain

Gray Matter

The outer areas consisting largely of neurons with myelinated axons

White Matter

Fibertracts consisting of myelinated axons

Electroencephalogram (EEG)

A recording of the electrical activity of large groups of cortical neurons just below the skull, most often using scalp electrodes

Magnetoencephalography (MEG)

Detects small magnetic fields generated by the electrical activity of neurons

* Allows for direct identification of areas of brain activation

Positron Emission Tomography (PET)

Brain-imaging method in which a radioactive sugar is injected into the subject and a computer compiles a color-coded image of the activity of the brain

Single Photon Emission Computed Tomography (SPECT)

Measures brain blood flow and uses more easily obtainable radioactive tracers than those used for PET

Functional MRI (fMRI)

MRI-based brain-imaging method that allows for functional examination of brain areas through changes in brain oxygenation

* Shows structure like a traditional MRI, but also function

Near-Infrared Spectroscopy (NIRS)

A functional brain imaging method that measures brain activity by using infrared light to determine changes in blood oxygen levels in the brain

* Limited to only recording from a couple of centimeters in depth from the cortical surface

Neuroanatomy

Each structure can have multiple names, be named by location, or in relation to other structures

Dorsolateral Prefrontal Cortex (DLPFC)

Portions of the prefrontal cortex toward top and away from midline

Medulla

The first large swelling at the top of the spinal cord, forming the lowest part of the brain, which is responsible for life-sustaining functions such as breathing, swallowing, and heart rateP

Pons

The larger swelling above the medulla that connects the top of the brain to the bottom and that plays a part in sleep, dreaming, left-right body coordination, and arousal

Reticular Formation (RF)

An area of neurons running through the middle of the medulla and the pons and slightly beyond that is responsible for general attention, alertness, and arousal

Reticular Activating System

Stimulates the upper part of the brain, keeping people awake and alertCer

Cerebellum

Part of the lower brain located behind the pons that controls and coordinates involuntary, rapid, fine motor movement and may have some cognitive functions

• Learned reflexes and habits are stored here to make them more or less automatic

• If it’s damaged, it causes you to be uncoordinated

Limbic System

A group of several structures located primarily under the cortex and involved in learning, emotion, memory, and motivationTh

Thalamus

Part of the limbic system located in the center of the brain, this structure relays sensory information from the lower part of the brain to the proper areas of the cortex and processes some sensory information before sending it to its proper area

Olfactory Bulbs

Two bulb-like projections of the brain located just above the sinus cavity and just below the frontal lobes that receive information from the olfactory receptor cells

Hypothalamus

Small structure in the brain located below the thalamus and directly above the pituitary gland, responsible for motivational behavior such as sleep, hunger, thirst, body temperature, and sex

Hippocampus

Curved structure located within each temporal lobe, responsible for the formation of long-term declarative memoriesA

Amygdala

Brain structure located near the hippocampus, responsible for fear responses and memory of fear

Cingulate Cortex

The limbic structure found in the cortex that can be divided into up to four regions that play different roles in processing emotional, cognitive, and autonomic information

* Active during many cognitive tasks such as selective attention, written word recognition, and working memory

Cortex

Outermost covering of the brain consisting of densely packed neurons, responsible for higher thought processes and interpretation of sensory input

Corticalization

Wrinkling of the brain that  allows a much larger area of cortical cells to exist in the small space inside the skullC

Cerebrum

The upper part of the brain consisting of the two hemispheres and the structures that connect them

Cerebral Hemispheres

The two sections of the cortex on the left and right sides of the brainC

Corpus Callosum

Thick band of neurons that connects the right and left cerebral hemispheres

Contralateral Organization

Each hemisphere is responsible for the opposite side of the body, either for control or for receiving information

Occipital Lobe

Section of the brain located at the rear and bottom of each cerebral hemisphere containing the visual centers of the brain

Primary Visual Cortex

Processes visual information from the eyes

Visual Association Cortex

 Identity and make sense of the visual information from the eyes

Parietal Lobes

Sections of the brain located at the top and back of each cerebral hemisphere containing the centers for touch, temperature, and body position

Somatosensory Cortex

Area of cortex at the front of the parietal lobes responsible for processing information from the skin and internal body receptors for touch, temperature, and body position

* The cells at the top of the brain receive information from the bottom of the body

Temporal Lobes

Areas of the cortex located along the side of the brain, starting just behind the temples, containing the neurons responsible for the sense of hearing and meaningful speech

* Contains the primary auditory cortex and the auditory association area

Primary Auditory Cortex

Processes auditory information from the ears

Auditory Association Cortex

Identifies and makes sense of auditory information

Language

What is the left temporal lobe involved with?

Frontal Lobes

Areas of the brain located in the front and top, responsible for higher mental processes and decision making as well as the production of fluent speech

Planning, personality, memory storage, complex decision making, and language

What are the higher mental functions of the brain?

Prefrontal Cortex (PFC)

PLinked to cognitive control, and especially executive functions (our ability to consider future outcomes and control of our current behavior to accomplish these goals)

• Include self-awareness, inhibition or self-restraint, working memory, time management, self-organization, and emotional self-control

• Associated with disorders of executive function such as ADHD

Preservation

A phenomena of making the same movement over and over

They may experience problems with performing mental or motor tasks

What happens to people with damage to the frontal lobe?

Motor Cortex

Rear section of the frontal lobe, responsible for for sending motor commands to the muscles of the somatic nervous system

Mirror Neurons

Neurons that fire when an animal or person performs an action and also when an animal or person observes that same action being performed by another

Association Areas

Areas within each lobe of the cortex responsible for the coordination and interpretation of information, as well as higher mental processing

* Help people make sense of the incoming sensory input

Broca’s Area

An area in the left frontal lobe associated with the production of speech (allows people to speak smoothly and fluently)

* Not responsible for the production of speech itself but for the interaction between frontal, temporal, and motor areas responsible for speech production

Broca’s Aphasia

Condition resulting from damage to Broca’s area, causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly

Wernicke’s Area

An area in the left temporal lobe that is involved in understanding the meaning of words