PSYC Exam 2

Nervous System

Composed of central system and the peripheral system

Central nervous system

Comprised of brain and spinal cord

Peripheral nervous system

Set of nerves that connects the CNS to the sensory organs, muscles, and glands; everything except brain + spinal cord; two main kinds of nerves that serve different tasks

Sensory neurons

Has to send information up to brain about what you touch

Motor neurons

Take commands from brain and send them to various parts of body

Sympathetic system (arousing)

Active when you are in some sort of arousing situation; marshal resources (accelerate heartbeat, etc.) as way of handling emergency

Parasympathetic system (calming)

Active when you are calm, at rest; relaxed (slow heartbeat, etc.), regular housekeeping/maintaining processes; stimulates digestive process, other activities that help regenerate/vitalize body

Two divisions of automatic nervous system

Sympathetic and parasympathetic; both active simultaneously

Spinal cord

Consists of bundles of nerves called tracts

Ascending tract

Carries sensory information brought in by spinal nerves up to the brain

Descending tract

Carries motor-control information down from the brain to be transmitted out by spinal nerves to muscles

Spinal cord injury

Unable to feel or move anything connected to body parts that are activated by spinal cord

Brainstem

Responsible for automatic survival functions, such as controlling breathing and heartbeat

Brainstem injury

Fatal injury

Cerebellum

Motor control, posture, balance, important for rapid, well-timed movements; in back of brain stem

Thalamus

Sensory relay station that receives input from most of sensory modalities → goes to rest of brain; vision, audition, etc.; does not process smell; relay station, input to other parts of brain that specialize in processing sensory information

Basal ganglia

Involved with motor control, especially intentional movements; slow, controlled movements; opposite of cerebellum; slow, deliberate motor movements

Basal damage

Produces "tremor at rest"; Parkinson's disease affects nerves running into this; cannot regulate hands in slow, fine-tuned way

Hypothalamus

Regulates many basic body functions, such as hunger, thirst, sleep, body temperature; motivation

Hypothalamus injury

Inability to sleep in certain way, inhibit/amplify feeling of hunger

Amygdala

Emotional regulator; one of key roles is processing and regulating emotional states; basic emotions require this; allows us to recognize emotions in other people; definitely involved with fear

Amygdala injury

Loss of "normal" emotion

Hippocampus

Key for building long-term memories; allow to learn, acquire new/encoding conscious memories; can't be where long-term memories are permanently stored

Hippocampus injury

Unable to acquire long-term memories, even though they retain memories prior to damage

Cerebral cortex

Outermost layer and largest part of brain, accounting for roughly 80% of total volume; ⅓ is visible, remaining ⅔ is hidden within many folds and fissures; divided into left and right hemispheres; four lobes/quadrants on each side

Principles of brain organization

Specialization of function; size/function correlations in functional areas; contralateral organization

Specialization of function

Bodily sensations (parietal lobe); speaking, imagining, thinking (frontal lobe); hearing and language comprehension (temporal lobe); vision (occipital lobe); widespread throughout brain

Motor cortex

Also called primary motor area; located at rear of frontal lobes and controls voluntary movements

Sensory cortex

Called primary somatosensory area; located at front of parietal lobes and registers body sensations

Size-function correlation

Sensitivity and function of body part depending on "real estate" devoted

Contralateral organization

Most of sensory and motor information that travels to and from brain goes to the opposite sides of body

Motor crossover

Sensory information coming from the right side of the body crosses by the left hemisphere, v.v.; motor control crosses from right hemisphere to left side of body, v.v.

Visual crossover

Left visual field to right hemisphere; right visual field to left hemisphere; within each eye

Corpus callosum

Large bundle of neural fibers (axons) connecting two brain hemispheres; main pathway that links and sends communication between two hemispheres

Left hemisphere

Language, right side of body, right visual field

Right hemisphere

Left side of body, left visual field

Aphasia

Impairment of language, usually caused by left hemisphere damaged to either Broca's area or Wernicke's area

Frontal lobe function

Involved with higher-level reasoning, ability to inhibit distracting/profane events, personality

Subcortical structures

Corpus callosum, thalamus, hypothalamus, brainstem, basal ganglia, cerebellum, hippocampus functions

Primary motor area

Basic command signals to move basic muscle parts; located in back of frontal lobe; map of body laid out

Primary sensory area

Processes basic information received from part of body; map of body laid out

Egas Moniz

Beneficial to put little rod up into frontal lobe through eye and disrupt connections in frontal lobe to treat illness like schizophrenia; gave us knowledge of function of frontal lobes; invasive brain manipulations with psychosurgery

Issues in brain imaging

Spatial and temporal resolution

Spatial resolution

How close in physical proximity can you get to target brain area activity

Temporal resolution

How close in time you can get to when the neurons communicate with each other

Electroencephalography

Measures electrical signals associated with neural firing in brain areas; excellent temporal resolution, poor spatial resolution, non-invasive; communication in brain in part involves electrical signals

Computed tomography scan

Version of X-ray; provides information about brain structure; air spatial resolution, no temporal resolution

Magnetic resonance imaging

Going into a gigantic magnetic machine to provide image; excellent spatial resolution, no temporal resolution, non-invasive

Functional MRI

Based on changed in oxygen consumption and blood flow, which are byproducts of neural activity; excellent spatial resolution, good temporal resolution, making inferences on activity; blood to some extent magnetic → brains that are active will have slightly more blood flow

Santiago Ramon y Cajal

Made cellular study of brain possible; using primitive microscope, identified basic shape of nerve; coined term "neuron"; realized it is basic building block of brain, elementary communication unit

Three major classes of neurons

Sensory, motor, interneurons

Sensory neurons

Receive information from senses, bring it up to brain; send input from sensory areas to brain and spinal cord

Motor neurons

Take motor commands from brain and send it down to body parts; send output from the brain spinal cord to muscles and glands

Interneurons

Connect one neuron to another, carry information between; carry information between other neurons; only located within brain

Structure of neuron, three basic parts

Dendrites, cell body, axon

Dendrites

Bushy, branching extensions of neuron that receive messages and conduct impulses toward cell body; the tree's roots; basic receiving unit

Axon

Extension of neuron, ending in terminal fibers, through which messages are sent to other neurons or to muscles or glands; one per cell, two distinct parts: tubelike structures + branches at end that connect to other cells; myelin sheath

Myelin sheath

White fatty casing on axon made of glial cells; acts as electrical insulator; increases speed of neural signals down the axon; whiteness of fatty cells that gives rise to "white matter"

Action potential

Basic communication element of all of us, fundamentally important; unidirectional; enhanced by myelin;
synapse separating neurons; combination of electrical signal and chemical through synapse

Synapse

Gap between axon tip of sending neuron and dendrite/cell body of receiving neuron; chemicals sending action potential to neuron

Neurotransmitter

Chemical messengers that traverse synaptic gap between neurons; effect on receiving neuron can either be excitatory (more likely to fire) or inhibitory (less likely to fire); communicate by mixture of electrical and chemical processes

SSRI

Selective serotonin reuptake inhibitor; treat depression, selective to serotonin; more serotonin left in synapse → more opportunity for neuron to receive it

Agonist

Drugs that increase effect of neurotransmitter

Antagonist

Drugs that interfere with effect of neurotransmitter

Neural development

Some takes place in womb and continues after birth until age 18 or so; occipital lobes finish developing first and the frontal lobes finish last

Plasticity

Neural tissue can reorganize in response to damage, if the brain is still developing; "wiring up" is not hard-wired, influenced by experience and brain damage

Sensation

Construction of "reality"; process by which sensory organs gather information about environment and transmit it to the brain; message that brain receives from one of senses

Stages of sensation

Stimulation → transduction → transmission → representation in brain

Transduction

To transform physical stimuli in the environment into neural signals in the brain

Six major senses

Taste, smell, hearing, touch, pain, vision

Taste

Bitter, sweet, salty, sour, umami

Taste receptors

Each taste bud has 50-150 receptor cells → send information to gustatory sensory neurons; sides of mouth, most on tongue

Smell

Chemical receptors in the nose, olfactory epithelium; fundamentally tied to taste

Frequency

Related to pitch of sound wave

Amplitude

Related to loudness of sound wave; high/low

Hertz

Unit of frequency

Major structures of ear

Outer, middle, inner ear

Outer ear

Acts as a funnel to direct sound waves towards inner structures

Middle ear

Consists of three small bones (or ossicles) that amplify the sound

Inner ear

Contains the structures that transduce sound into a neural response

Chlochea

Filled with fluid, lined with hair cells that are key to transducing sound waves into neural signal; higher pitched on outside, deeper on inside; stirrup pushes against oval window that fluctuates depending on pitch sound → fluid moves and activates hair cells → how brain interprets corresponding pitch

Hair cells

Once cells are gone, they never recover; cells highly correlated with age, systematically go away; higher pitched cells destroyed quicker, on outside

Touch receptors

Sensory neurons all over skin

Neural pathways that code pain

A-delta and C-fibers

A-delta fibers (myelinated)

Thick, fast conducting neurons; quick, sharp pain; comes first

C-fibers (unmyelinated)

Thin, slow conducting neurons; slow, throbbing pain; comes last

Gate-control theory

Explains variability in experience of painful events; argues that spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain; one same wound may not feel as painful as another due to context and release of endorphins

Phantom limb pain

Experience of pain not always originate from pain receptors, can be generated from brain

Purpose of visual system

To transform light energy into a neural impulse; represent characteristics of objects in our environment such as size, color, shape, and location

Compound eyes

Multiple lenses; very sensitive to motion, acuity good; inefficient for resolution

Simple eyes

Single lens; works like an old-fashioned camera, using lens to focus light onto photo-sensitive surface at back of sealed structure

Retina

At back of eye, consists of series of layers; rods + cones most important part: receptor cells that do transduction work; light shine through layers of retina to rods and cones that convert light energy into signal brain can understand; sends signal to optic nerve

Rods and cones

Photoreceptors which transduce energy in light into neural response

Cones

Permit color vision and are most concentrated in fovea (pinhead-size area of retina that is in most direct line of sight)

Rods

Permit vision in dim light and are in everywhere except in fovea, distributed basically everywhere in retina

Blind spot

Region with no rods or cones; relatively sizeable

Electromagnetic spectrum

We only see sliver of huge dimension of wavelengths, this

Key aspects of light

Visual system interprets differences in wavelength of light as color; visual system interprets differences in the amplitude of light as intensity

Opponent Process Theory

Account for phenomena like complementary afterimages, Ewald Herring proposed that we have different types of color-opponent cells; red-green, blue-yellow, black-white opponent cells

Primary visual area/cortex

First region that receives visual information in occipital lobe; very rudimentary way, cells within primary region that are sensitive to very simple features in the world