PSY 340 - EXAM 1

Themes of Class

• Perception happens in the brain

• The mind is the brain (also called monism)

• Brains differ from each other

• Maybe it’s biology

Biological Explanations of Behavior (Physiological)

links behavior to body/brain activity

Biological Explanations of Behavior (Functional)

purpose of behavior (why it evolved)

Biological Explanations of Behavior (Ontogenetic)

development of behavior across lifespan

Biological Explanations of Behavior (Evolutionary)

evolutionary history of behavior

Ethical Issues of Animals in Research (Minimalists)

some animal research is acceptable, but use IACUC and Replace, Reduce, Refine (Responsibility)

Neurons

receive and transmit information to other

Glia

Hold neurons in place

Supply neurons

Insulate neurons

Destroy pathogens

Modify neural function

Presynaptic terminal

release neurotransmitters

Efferent neuron

carries information away from the structure (motor)

Afferent neuron

brings information into a structure (sensory)

Intrinsic neuron

stays within a structure

Types of Glia (Astrocytes)

synchronize activity

modifies transmission

responds to blood flow changes

Types of Glia (Microglia)

removes waste & pathogens

Types of Glia (Oligodendrocytes & Schwann cells)

myelin sheaths for axons in CNS and PNS

Types of Glia (Radial Glia)

guide migration of neurons

Blood Brain Barrier

tight endothelial cells

blocks toxins

allows small uncharged molecules to pass (BUT active transport brings glucose, hormones, and amino acids through)

Thiamine (vitamin B1)

prolonged deficiency can lead to death of neurons and Korsokoff’s Syndrome (severe memory impairments)

Phases of Neural Activity

1. Resting Potential

2. Action Potential

3. Refractory Period

Resting Potential

the stable, negatively charged electrical state of a cell's membrane when it is not stimulated or undergoing activity

-70mV (inside is negative)

Forces acting on ions: electrical and [ ] gradient

Sodium-potassium pump (pumps 3Na+ out, K+ in, and requires energy)

Action Potential

a rapid electrical signal that travels down a neuron's axon to communicate with other cells, including neurons, muscles, and the heart

Stimulus —> depolarization

Voltage-gated Na+ channels open & Na+ rush in

Propagation

begins at axon hillock

AP regenerates at each section of axon

cannot travel backwards bc previous segment is in refractory period

Myelin & Saltatory Conduction

Occurs as action potentials jump from node to node due to the Myelin

Refractory Period

a temporary state of unresponsiveness that occurs after a cell or tissue has been stimulated

• Absolute (~1ms) —> no AP possible

• Relative (2-4ms) —> strong stimulus required

Synapses

specialized junction between two neurons or between a neuron and a muscle or gland cell

Reflex Arc

the neural pathway responsible for rapid, involuntary responses to stimuli

Reflex Arc (Sensory Neuron)

Converts the stimulus information into AP

Reflex Arc (Interneuron)

relays signals within CNS

Reflex Arc (Motor Neuron)

sends commands to effector (muscles, glands)

Sherrington

discovered that reflexes are slower than axon conduction speed (means that there’s a synapse)

Synaptic Delay

time between sensory input and motor output —> extra delay due to chemical transmission

Temporal summation

repeated stimuli in rapid succession —> combined effects

Spatial summation

multiple presynaptic neurons firing at the same time —> combined

Graded Potentials (discovered by Eccles)

a short-distance, temporary, and localized change in a cell's membrane potential, with its magnitude varying directly with stimulus strength

Excitatory Post-Synaptic Potentials (EPSP)

excitatory depolarization that moves membrane potential closer to threshold

EPSPs summate may trigger action potential

Inhibitory Post-Synaptic Potentials (IPSP)

inhibitory hyperpolarization that moves membrane potential farther from threshold

makes firing LESS likely to happen

Inhibitory Synapses

allows coordinated movement EX: when biceps fire, triceps relax

IPSP = graded hyperpolarization

Spontaneous Firing Rate

neurons fire at a baseline rate even without input

increase EPSPs —> increase firing

increase IPSPs —> decrease firing

Neuronal Connectivity

web of synapses between neurons in the brain that underlies all neural function and behavior, such as thought, emotion, and movement

T. R. Elliot

suggested that chemicals on organs mimic nerve stimulation

was initially ignored due to Sherrington’s influence

Otto Loewi

discovered neurotransmitters (true of most synapses)

Experimental Design:

• Two frog hearts were isolated One heart (Heart A) still had its vagus nerve intact, the other (Heart B) had its vagus nerve removed.

• Heart A was placed in a chamber filled with nutrient solution. The vagus nerve of Heart A was electrically stimulated, causing it to slow down.

• The nutrient solution from Heart A was then transferred to the chamber containing Heart B. Heart B also slowed down, even though its vagus nerve had been removed

Anatomy of a Synapse

Vesicles hold NT

Presynaptic terminal releases NT

Synaptic clef between neurons

Postsynaptic terminal receives NT

Neurotransmitters

Chemicals produced and released by one neuron that affect another neuron

EX:

• Amino acids: GABA (inhibitory), Glutamate (excitatory), Acetylcholine (ACH)

• Neuropeptides: Endorphins, Substance P

• Monoamines: Serotonin, Dopamine, Epinephrine, Norepinephrine

• Purines: ATP, adenosine

• Gases: nitric oxide

  
  

Synthesis of Neurotransmitter

Neurons synthesize neurotransmitters from substances in the diet.

EX:

• Choline —> ACH (Peanuts, meat, fish, milk, broccoli, cabbage)

• Phenylalanine —> Tyrosine —> Dopamine —> NE → Epinephrine

• Tryptophan —> Serotonin (Turkey, bananas,

  eggs)

Phenylketonuria

genetic disorder that affects the body's ability to break down the amino acid phenylalanine

Exocytosis

1. AP arrives

2. Voltage-gated Ca2+ channel opens

3. Ca2+ causes vesicles to fuse w membrane

4. NT diffuses across synapse

5. NT binds to receptors

Ionotropic Receptor

Fast, short duration

Open ion channels directly

Used for quick actions

NT EX: Glutamate, GABA, ACh

Metabotropic Receptor

Slower, long-lasting

Activate G-protein —> 2nd messenger —> widespread cell effects

NT EX: Dopamine, Serotonin

Neuropeptides

chains of amino acids produced and released by neurons that act as chemical messengers

produced in soma

require repeated stimulation to release

released from dendrites and cell body

spread widely, long-lasting effects

EX: Substance P, endorphins

Hallucinogenic Drugs (EX: LDS)

mimics serotonin

activate receptors at wrong time —> sensory distortions

Opiates (EX: Heroin, Morphine)

binds to opioid receptors

same receptors endorphins naturally binds to

reduce pain, increase reward

Stimulants

Amphetamine, methamphetamine, cocaine —> blocks dopamine reuptake (increase dopamine)

Ritalin, methylphenidate —> same mechanism as cocaine but controlled dosage

Inactivation of neurotransmitters

Diffuse away

Enzymatic breakdown (MOA breaks down monoamines, AChE breaks down ACh)

Reuptake into presynaptic neuron (via transporter proteins)

Negative Feedback Methods

Auto-receptors

Postsynaptic chemicals

Auto-receptors

presynaptic neuron that monitors its own NT release (negative feedback)

Postsynaptic chemical

signals back to presynaptic neuron via chemicals (NO, Anandamide, 2-AG —> marijuana enhance pathways)

Electrical Synapses

Rare and few

Gap junctions = direct ion flow

Very fast, depolarizes both cells simultaneously

Important in escape reflexes, breathing rhythms

Hormone Characteristics

released into bloodstream

long-lasting effects

some substances serve as both NTs and Hormones

Pituitary Glands

Stimulated by hypothalamus

Anterior pituitary releases: ACTH, FSH, LH, GH, prolactin, TSH

Posterior pituitary releases: oxytocin & vasopressin

CNS

brain and spinal cord

PNS

Somatic NS (voluntary muscles)

Autonomic NS (involuntary muscles)

Cranial Nerves

ANS

Sympathetic (arousing)

Parasympathetic (calming)

Enteric NS

Tract

set of axons inside CNS

Nerve

set of axons in the PNS

Ganglion

cluster of soma outside CNS

Nucleus

cluster of somas inside CNS

Lamina

layer of cell bodies (esp in cortex)

Sympathetic Nervous System

increases arousal

has a chain of ganglia outside spinal cord

Functions as single, unified system

NT: norepinephrine

Parasympathetic Nervous System

Calms body

Preganglionic axon from spinal cord —> ganglia

Postganglionic fibers from ganglia —> organs

NT: acetylcholine

Spinal Cord

Extension of brain

Gray matter = soma + dendrites

White matter = myelinated axon

Dorsal Root Ganglia

clusters of sensory neuron somas located outside spinal cord

bring sensory info INTO CNS

Hindbrain (Rhombencephalon)

Medulla

Pons

Cerebellum

Medulla

vital reflexes (breathing, heart rate, vomiting) and connects to cranial nerves

Pons

arousal, dreaming, houses RETICULAR FORAMEN and RAPHE SYSTEM (serotonin)

Cerebellum

Movement/coordination, Balance, Timing, & Attention shifting

Midbrain (Mesencephalon)

Tectum

Tegmentum

Substantia Nigra

Tectum

Superior Colliculus (visual reflex)

Inferior colliculus (auditory processing)

Tegmentum

Nuclei for cranial nerves III & IV

Part of Reticular Formation

Pathways linking to forebrain and spinal cord

Substantia Nigra

Dopamine neurons (loss of these —> Parkinson’s)

Forebrain

Cerebral Cortex

Thalamus

Hypothalamus

Amygdala

Cerebral Cortex

Main outer covering of brain

Thalamus

center of forebrain & sensory info relay station

Hypothalamus

motivated behaviors (hunger, sex, thirst, temp)

controls autonomic NS

sends signals to pituitary gland

Amygdala

Emotional processing

Subcortical Forebrain

Basal Ganglia

Basal Forebrain

Hippocampus

Basal Ganglia

Caudate nucleus —> motor control, learning, memory, and executive functions

Putamen —> motor control

Globus pallidus —> movement, habits, decision-making

Basal Forebrain

nucleus basalis —> regulates cognitive and behavioral processes

releases acetylcholine to cortex

arousal, attention, learning

Hippocampus

Between thalamus and cortex

formation of new memories

CSF

clear fluid that cushions the brain, circulates and reabsorbed by blood in subarachnoid space. Formed by choroid plexus

Blockage —> increase pressure —> cognitive impair

Cerebral Cortex Communication

via corpus callosum and anterior commissure

Occipital lobe

posterior cortex

contains primary visual cortex

damage —> cortical blindness

Parietal lobe

anterior to occipital, posterior to central sulcus

contains primary somatosensory cortex

receives info abt touch, muscle stretch, and join receptors

important for spatial processing and body awareness

Temporal lobe

lateral cortex

functions: language, face recognition, and emotion

damage —> Kluver-Bucy syndrome (emotional & behavioral abnormalities)

Frontal lobe

Precentral Gyrus (primary motor cortex, controls voluntary movement)

Prefrontal cortex (working memory, planning, decision-making, delayed-response tasks)