psych

physiological- biological explanation of behavior

relates behavior to the activity of the brain and other organs

ontogenetic- biological explanation of behavior

describes the development of a structure or behavior

evolutionary- biological explanation of behavior

reconstructs evolutionary history of a behavior or structure

functional- biological explanation of behavior

describes *why* a structure or behavior evolved as it did

Dualism

the physical body and the mind (or the soul) are separate entities

Monism

there is only matter and energy, so the mind must be produced by the workings of the nervous system

Materialism

existence of material / physical substance only (the mind does not exist)

Mentalism

only minds exist (no physical world without a mind to be aware of it)

The Mind-Body problem

How do physical properties like nerve impulses or sodium and potassium ions flowing across a membrane transform into the richness of perceptual, emotional, and cognitive experience?

Defining Consciousness

* •Something that we are aware of and can communicate with others
* • Brain activity
* • Perception (attention? / experience?)

Blindsight

 \* People with damage to the visual cortex

* Stroke, head injury
* Deny seeing objects that fall in damaged \n areas, but they can interact with them

Split-brain

   \* Cutting the corpus callosum

* In the past, this was sometimes used for \n cases of severe epilepsy.
* Some amount of information is \n still being communicated via \n the commissures

Spatial Neglect

\* Damage to the right parietal cortex causes \n difficulty in paying attention to left side.

* Tend to ignore… \n the left sides of objects \n the left side of space \n the left side of their body
* Specific to attention NOT \n necessarily perception itself

Reticular Theory

large network of fused nerve cells

Neuron Theory

cells as distinct elements that make up nervous system

Glia

* Supply nourishment to the neurons
* Remove waste material
* Provide insulation around many axons
* Myelin sheaths derived from special type of glial cells
* Literally – “glue”
* \~ 10 glial cells per 1 neuron in cerebral cortex
* Over 50% of brain’s volume

Neurons

 receive, integrate and transmit information (ie. responsible for communication)

Soma

the cell body: contains cell nucleus & & much of the chemical machinery (the mechanisms to keep the cell alive)

Dendrites

branch out and receive signals

Axons

transmit info away; filled with fluid that conducts electrical signals

Interneurons

communicate with other nerves

Sensory neurons

receive signals from outside the nervous system

Motor neurons

carry messages from neurons to the muscles

Presynaptic terminals

end points of an axon where the release of chemicals occurs for communication with other neurons

Afferent axon

refers to bringing information into a structure

Efferent axon

refers to carrying information away from a structure

Interneurons/intrinsic neurons 

dendrites and axons are completely contained within a single structure

Microglia

remove waste material and other microorganisms that could prove harmful to the neuron \n → immune system

Astrocytes

1. Structural matrix = hold neurons in place
2. Supply glucose and nourishment to neurons \n by metabolizing nutrients from capillaries
3. Blood-brain barrier
4. Clean up debris
5. Isolation of synapse

Astrocytes

help synchronize the activity of \n functionally related axons \n by wrapping around \n the presynaptic terminals \n and taking up \n chemicals released \n by the axon

Oligodendrocytes

in the brain & spinal cord

* build the myelin sheath that \n surrounds and insulates certain \n vertebrate axons

Schwann cells 

in the peripheral nervous system

* build the myelin sheath that \n surrounds and insulates certain \n vertebrate axons

Schwann cells 

Schwann cells aid in the \n digestion of the dead and dying \n axons then arrange themselves in a series of cylinders, guiding the regrowth of damaged axons

Radial glia

guide the migration of neurons and the growth of their axons and dendrites during embryonic development

* When embryonic development finishes, most radial glia differentiate into neurons and a smaller number differentiate into astrocytes and oligodendrocytes

blood-brain barrier

a mechanism that surrounds the brain and blocks most chemicals from entering

Active transport

protein-mediated process that expends energy to pump chemicals from the blood into the brain

electrical gradient/polarization

A difference in the electrical charge inside and outside of the cell

resting potential

the state of the neuron prior to the sending of a nerve impulse

When the membrane is at rest

Sodium channels are closed

\
Potassium channels are partially closed allowing the slow passage of potassium

Hyperpolarization

increasing the polarization or the difference between the electrical charge of two places

Depolarization

decreasing the polarization towards zero

threshold of excitation

level above which any stimulation produces a massive depolarization

action potential

rapid depolarization of the neuron

What happens when nueron is stimulated

membrane becomes selectively permeable to sodium = Sodium channels

* Positively charged sodium ions (Na+) flow into neuron
* The neuron is returned to its resting state by the opening of potassium channels
* Potassium ions flow out due to the concentration gradient and take with them their positive charge

sodium-potassium pump

pumps three sodium ions out of the cells while drawing two potassium ions into the cell

* helps maintain electrical gradient

all-or-none law

* receives a signal of sufficient strength, it fires. If the signal is too weak, it does not fire
* Fires to end without decreasing in size

refractory period

the neuron resists the production of another action potential

absolute refractory period

the first part of the period in which the membrane cannot produce an action potential

relative refractory period

the second part in which it takes a stronger than usual stimulus to trigger an action potential

nodes of Ranvier

unmyelinated sections in which the action potential is regenerated

Saltatory conduction

* used to describe the “jumping” of the action potential from node to node
* rapid conduction of impulses
* conserves energy for the cell

Sherrington

The spinal cord controls the flexion and extension reflexes

* Noted several observations


1. reflexes are slower than conduction along an axon
2. several weak stimuli presented at different times or locations produce a stronger reflex than a single stimulus
3. When one set of muscles becomes excited, another set becomes relaxed

Temporal summatio

a light pinch did not produce the reflex, but a few rapidly repeated pinches did

Excitatory Postsynaptic \n  Potentials \[EPSPs\]

graded potentials \n  graded depolarization

Spatial summation

synaptic inputs from separate locations combine their effects on a neuron

Inhibitory Postsynaptic \n Potentials \[IPSPs\]

Graded hyperpolarizations

Sequence

1. Neuron synthesizes chemicals that serve as NTs
2. When the membrane of the terminal button is depolarized by the action potential, calcium channels (Ca2+) open.
* Released molecules diffuse across the cleft
3. Released molecules attach to receptors and alter the activity of the postsynaptic neuron
4. NT molecules separate from their receptors
5. A number of outcomes for neurochemicals after influencing receptor sites

What happens after…

* NTs can be broken down by enzymes \[recycling system\]
* Reuptake
* Diffuse away

Negative feedback…

1. The postsynaptic cell may send reverse messages to slow the release of further neurotransmitters by presynaptic cells
2. Receptor sites on presynaptic terminals that respond to NTs released by postsynaptic neuron AND receptor sites for the same NT they release (autoreceptors) \n → respond by inhibiting further synthesis and release \n

Agonist

mimics neurotransmitter action

Antagonist

opposes action of a neurotransmitter

Acetylcholine

* Controls every move you make: walking, running, typing
* Contributes to the regulation of attention, arousal and memory
* dysregulation of ACh: 

\- Alzheimer’s Disease

Glutamate

* Serves as widely distributed excitatory transmitter
* Involved in learning and memory
* Involved in autonomic nervous system reactions
* dysregulation of Glutamate:

\- Schizophrenia

GABA \[gamma-aminobutyric acid\]

* Serves as widely distributed inhibitory transmitter
* Lowers arousal, anxiety, and excitation. 
* Facilitates sleep

\
* Valium and similar anti-anxiety drugs work at GABA synapses 
* Alcohol indirectly increases activity at synapses releasing GABA
* Dysregulation of GABA:

\- Anxiety disorders

Dopamine

* Contributes to the control of voluntary movement
* Dopamine circuits in medial forebrain bundle characterized as “reward pathway”
* Disorders associated with dysregulation of DA:

\- Parkinsonism

\- Huntington’s

\- Schizophrenic disorders

\- Addictive disorders

* \
* Cocaine and amphetamines elevate activity at DA synapses (Cocaine interferes with process of reuptake)

Norepinephrine

* Contributes to modulation of mood, arousal, & vigilance
* Contributes to attention to new or important stimuli
* Implicated in memory
* \
* Cocaine and amphetamines elevate activity at NE synapses
* Disorders associated with dysregulation of NE:

\- Depressive disorders

Serotonin

* Involved in the regulation of sleep and wakefulness, eating and aggression
* Disorders associated with dysregulation of Serotonin:

\- Depressive disorders

\- Obsessive-compulsive disorders

\- Eating disorders

\
* Prozac and similar antidepressant drugs affect serotonin 

Nitric Oxide

* A gas released by small local neurons when they are active
* Highly active brain areas = more nitric oxide released = dilation of blood vessels and more blood flow to that area

Ionotropic effects

* Opening and closing of ligand-gated channels (transmitter-gated channels)
* Occurs within 1 msec with half-life of 5 msec
* Important for information where speed of updates is important (e.g., visual & auditory information)

Metabotropic effects

* Second messenger systems
* Initiate a sequence of metabolic reactions
* Emerge 30 msec or more after the release of NTs, typically last up to a few seconds, sometimes longer
* Many NT’s \[serotonin, dopamine, norepinephrine, sometimes glutamate & GABA\]

Endorphins

“Endogenous morphine”
Resemble opiate drugs in structure and effects
Inhibitory
Play role in pain relief and response to stress
Contribute to regulation of eating behavior

CNS

brain & spinal cord

PNS

Nerves not in CNS

Spinal Nerves

Nerves leave the vertebral \n column and travel to the muscles or sense organs  \n they innervate

Sympathetic N.S.

a network of nerves that prepares the organs for vigorous activity = chains of ganglia just to the left and right of the thoracic and lumbar areas of the spine

\
Preganglionic axons \n enter the ganglia of \n the sympathetic chain.

Postganglionic neurons \n send axons to target \n organs \n

* Exception: \n adrenal medulla

parasympathetic

* Cranialsacral system

\

Long preganglionic axons \n extend from spinal cord

Shorter postganglionic \n fibers then extend into \n organs

\
* Not linked so more \n independent


* returns the body to its resting state

Sympathetic Nervous System

* Epinephrine
* Blood flows to skeletal muscles
* Causes piloerection

PARASYMPATHETIC

Preganglionic and Postganglionic axons of the parasympathetic nervous system mostly release acetylcholine as a neurotransmitter

SYMPATHETIC

Terminal buttons of preganglionic axons secrete acetylcholine. \n Terminal buttons on the target organs secrete norepinephrine (except acetylcholine at a few, like at sweat glands)

Central Nervous System

* Brain
* Spinal Cord

The Ventricles

* Nervous system starts as a tube surrounding a fluid canal
* Canal persists into adulthood as central canal (fluid-filled channel in center of spinal cord) and as the ventricles (four fluid-filled cavities within the brain)

choroid plexus

produce cerebrospinal fluid (CSF)

produce cerebrospinal fluid (CSF)

* CSF flows from lateral ventricles \n to third and fourth ventricles
* From fourth ventricle: Some flows into central canal of spinal cord More flows to meninges \n

The Spinal Cord

* Part of CNS within spinal column
* Reflexes
* Gray matter packed with cell bodies & dendrites
* White matter  mostly myelinated axons

Dorsal  roots

contain incoming sensory fibers (afferent)

Ventral roots

contain outgoing motor fibers (efferent)

Brain stem

* medulla, pons, \n midbrain, and certain \n central structures \n of the forebrain

The Hindbrain

medulla, pons, cerebellum

medulla

* Enlarged extension of the spinal cord into the skull
* Controls vital reflexes through the cranial nerves
* Breathing
* Heart rate
* Vomiting
* Salivation
* Coughing and sneezing

\[sensations and muscle movements of the head, much of the parasympathetic output to the organs\]

Pons

* Anterior to the medulla
* Contains nuclei for several cranial nerves
* Acts as a bridge between right half of brain to left half of spinal cord and vice versa

Cerebellum

* Control of movement
* “balance & coordination”
* attention shifting \n  (auditory and visual)
* perceptual timing, \n  cognitive timing, \n  social timing

The Midbrain

Tectum, Tegmentum

Tectum (“roof”)

Swellings on each side = \n superior colliculus \[vision\] \n inferior colliculus \[hearing\]

Tegmentum (“covering”)

parts of the Reticular Formation 

Periaqueductal Gray Matter

Substantia Nigra

\

Reticular Formation 

* Core of the brain stem
* Receives sensory info; projects to cerebral cortex, thalamus and spinal cord

Periaqueductal Gray Matter

* Controls sequences of movements that constitute species-typical behaviors
* Involved in pain perception

Substantia Nigra

Dopamine-containing pathway that facilitates readiness for movement

Limbic system

border around the brainstem \n - motivation, emotion, drives, and aggression

* Olfactory bulb
* Hypothalamus
* Hippocampus
* Amygdala
* Cingulate gyrus

Diencephalon

thalamus & hypothalamus

Thalamus

* receives & processes \n sensory info (except olfaction)
* sends projection fibers to cerebral cortex which communicates back