Physiological Psychology Exam 1

Experimental ablation

Used to determine the function of a brain region by damaging it and observing changes in behavior

How does experimental ablation work

animal is anesthetized, a hole is drilled in the skull, an electrode or chemical is used to produce a lesion, behavior is evaluated after

Limitations of experimental ablation

brain regions perform multiple functions, brain regions are interconnected, damaging one area can affect other functions

CT/CAT scan

uses x-rays, produces images of the skull and its contents, and is useful for detecting tumors and bleeding

MRI

Uses a magnetic field and radio waves, produces detailed images/slices of the brain, more detailed than CT, has poorer temporal resolution than PET

PET

Measures neurochemical changes in the living brain, uses radioactive 2DG

Limitations of PET

Expensive, poorer spatial resolution, poorer temporal resolution

fMRI

Detects metabolic/chemical changes, increased brain activity = increased blood flow, measures the blood oxygen level dependent (BOLD) signal, has high spatial resolution

Microelectrodes

Record electrical activity from individual neurons, can be permanently implanted

Central nervous system

Brain and spinal cord

Peripheral nervous system

everything outside the CNS, nerves connecting through CNS with the rest of the body

Neuron structure

Dendrites, soma, axon, terminal button, synapse

Dendrites

Receive information from other neurons, have spines that increase surface area for synapses

Soma

Cell body, contains the nucleus and other organelles, handles the cell’s basic life processes

Axon

Long structure that carries information away from the soma, often covered in myelin

Myelin sheath

Fatty insulation around axons, speeds neural conduction

Axon collateral

A branch coming off an axon

Terminal button

End of the axon, forms synapses with other cells

Synapse

Junction where information passes between neurons

Multipolar neuron

Many dendrites, one axon

Bipolar neuron

One dendrite, one axon

Monopolar Neuron

One branch leaves the cell body and extends in two directions

Sensory neurons

Carry information from the periferal nervous system to the central nervous system

Motor neurons

Carry messages that stimulate muscles or glands

Interneurons

Receive input from neurons, send output to other neurons, make up the majority of neurons in the brain

Astrocytes

Physical support, supply chemicals, synapse formation and pruning, phagocytosis

Microglia

Immune response, remove debris and damages cells

Oligodendrocytes

Produce myelin in the central nervous system, can produce multiple myelin segments

Schwann cells

Produces myelin in the peripheral nervous system, provides one myelin segment

Diffusion

Molecules move toward areas of lower concentration

Electrostatic pressure

Charged molecules are attracted to opposite charges, like charges repel

Ion distribution inside the cell

K+ and A-

Ion distribution outside the cell

Na+ and Cl-

Sodium potassium pump

Uses ATP to pump 3 Na+ out and move 2 K+ in

Action potential

A brief large change in the neuron’s polarization

Threshold of excitation

The stimulus intensity necessary to trigger an action potential, -50 to -40 mV for most neurons

All or none law

An action potential either happens or it does not happen, once triggered, its size remains constant as it travels down the axon

Action potential sequence

Depolarization, Repolarization, Hyperpolarization

Depolarization

Membrane becomes less negative, Na+ channels open, Na+ enters

Repolarization

Na+ channels close, K+ channels open, K+ leaves the neuron, membrane becomes more negative again

Hyperpolarization

Interior temporarily becomes more negative than resting level

Saltatory conduction

Occurs in myelinated axons, the action potential effectively jumps from one node of ranvier to the next

Presynaptic membrane

Sends information and releases the neurotransmitter

Synaptic cleft

Gap that separates the pre and post synaptic neurons

Postsynaptic membrane

Receives the information, responds to the neurotransmitter sent by the presynaptic neuron

Synaptic vesicles

Store neurotransmitters

Receptors

Receives neurotransmitters

Steps of synaptic transmission

Synthesis, release, receptor activation, ionotropic receptor

Synthesis

Neurotransmitters are produced and stored in vesicles

Release

Action potential reaches terminal, voltage sensitive CA2+ channels open, Ca2+ enters, vesicles fuse with the presynaptic membrane, neurotransmitter is released.

Exocytosis

The release of a neurotransmitter

Receptor activation

Neurotransmitter crosses the synaptic cleft and binds to a receptor

Ionotropic receptor

Opens an ion channel directly

Metabolic receptor

Activates a G protein, G protein activates an enzyme, produces a second messenger, can eventually affect ion channels and cellular activity

Deactivation

Neurotransmitters can be removed through diffusion, degradation, or reuptake

Diffusion

Neurotransmitter moves away from synapse

Degradation

Enzymes break neurotransmitter down

Reuptake

Transporter proteins bring neurotransmitter back into presynaptic terminal

Excitatory postsynaptic potential (EPSP)

Depolarized the postsynaptic neuron, increases likelihood of firing an action potential

Inhibitory postsynaptic potential (IPSP)

Hyperpolarizes the postsynaptic neuron, decreases likelihood of firing

Blood brain barrier

A semipermeable barrier between blood and brain

Functions of the blood brain barrier

Regulates extracellular fluid, helps regulate neural transmission, prevents potentially harmful chemicals from reaching the brain

Meninges

Protective sheaths around the brain and spinal cord, dura mater, arachnoid membrane, pia mater

Dura mater

Durable, thick, tough outer layer

Arachnoid membrane

soft, spongy middle layer

Pia mater

Delicate, thin inner layer, clings to the surface of the brain

Cerebrospinal fluid

Surrounds the brain and spinal cord, helps the brain float, reduces shock

What are the four ventricles

Lateral ventricles, third ventricle, fourth ventricle

Lateral ventricles

Largest, one in each cerebral hemisphere

Third ventricle

Located at the midline

Fourth ventricle

Located toward the ventral side of the brain

Cerebral aqueduct

Connects the third and fourth ventricles

Sulci

Small grooves in the brain

Fissures

Large grooves in the brain

Gyri

Bulges between grooves

Gray matter

Primarily cell bodies

White matter

Primarily myelinated axons

Corpus callosum

Large bands of axons connecting the left and right hemispheres

Contralateral organization

Each hemisphere receives sensory information from and controls movement on the opposite side of the body

Frontal lobe

Movement, planning, decision making

Parietal lobe

Body sensations, spatial cognition

Occipital lobe

Vision

Temporal lobe

Hearing, olfaction, some learning and memory

Subcortical structures

Basal ganglia and the limbic system (hippocampus and amygdala)

Basal ganglia

Movement, learning, memory, habits

Hippocampus

Learning, personal memory, spatial navigation

Amygdala

Emotions, emotional memories, recognizing emotional signals in others

Diencephalon

Thalamus and hypothalamus

Thalamus

Relay station, relays sensory and nonsensory information to cortex, almost all information reaching the cortex passes through it, not smell

Hypothalamus

Smart control center, feeding, sexual activity, sleep, emotional expression, temperature regulation, endocrine regulation, motivated behavior

Midbrain

Tectum and tegmentum

Tectum

Visual and auditory information

Tegmentum

Reticular information

Cerebellum

Coordinates movement

What does damage to the cerebellum cause

Jerky movements, poor coordination, exaggerated movements

Pons

Sleep/wake regulation, arousal, relays information from cortex to cerebellum

Medulla

Most caudal part of the brainstem, connected to the spinal cord

What is the medulla important for

Cardiovasuclar regulation, respiration, skeletal muscle tone

Neurotransmitter

Chemical released from the synaptic terminal that communicates between neurons

Neuromodulator

Acts like a neurotransmitter but is not restricted to the synaptic cleft and can diffuse through extracellular fluid