Psych topic 3 + 4

Neurons

Communicate with one another/building blocks of the nervous system

Basic parts of a neuron

1. Cell body

2. Dendrites

3. Axon

Cell body - contains DNA

Coordinates the information processing tasks; keeps the cell alive

Dendrites

Receives information from other neurons and relays it to the cell body

Axon

Transmits information to other neurons, muscles or glands

Myelin sheath

Insulating layer of fatty material to speed up neuron transfer

What causes multiple sclerosis(MS)

Deterioration of the myelin sheath

Synapse

The region between the axon of one neuron and the dendrites or cell body of another

Major types of neurons

1. Sensory neurons

2. Motor neurons

3. Interneurons

Sensory neurons

Receive information from the external world and convey this information to the brain via the spinal cord

Motor neurons

Carry signals from the spinal cord to the muscles to produce movement

Interneurons

Connect sensory neurons, motor neurons or other interneurons

Purkinje cells

Type of interneuron that carries information from the cerebellum to the rest of the brain and spinal cord; helps coordinate fine motor movement

Pyramidal cells(Triangular cell body)

Found in the cerebral cortex

Bipolar cells(Single axon and dendrite)

Sensory neuron found in the retinas of the eye

Mirror neurons

Found in frontal and parietal lobes; activated when an animal performs a behaviour or when it observes another animal performing a behavior

What is ASD

Associated with impairments in the function of mirror neurons; struggling with the interpretation part

2 stages of neurons communicating information(Electrochemical action of neurons)

1. Conduction

2. Transmission

Conduction

conduction of an electrical signal over relatively long distances within neurons, from the dendrites, to the cell body, then throughout the axon

Transmission

transmission of chemical signals between neurons over the synapse

Resting potential

The difference in electrical charge between the inside and outside of a neurons cell membrane. high concentration of positively charged sodium ions and negatively charged chloride ions outside the neurons cell membrane; negatively charged protein ions inside the neurons cell membrane; potassium channels are open

Action potential (all or nothing)

An electrical signal that is conducted along the length of a neurons axon to the synapse; reaches threshold, then positively charged sodium ions open, which increases the positive charge inside the axon, and pushes the action potential to its maximum value of +40mV; then goes through the refractory period - pump

Saltatory conduction

Helps speed the flow of information down the axon - charge jumps from node to node

Terminal buttons

Knoblike structures that branch out from an axon and is filled with vesicles - which contain neurotransmitters

Neurotransmitters

Chemicals that transmit information across the synapse to receiving neurons dendrites

Receptors

Parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electrical signal

Terminal signaling

Neuro transmitter and receptor sites act like a lock and key system

Neurotransmitters leave the synapse through what three processes

1. Autoreceptors

2. Reuptake

3. Enzyme deactivation

Autoreceptors

Detect how much of a neurotransmitter has been released into a synapse and signal the neuron to stop releasing neurotransmitters when an excess is present

Reuptake

Neurotransmitters are reabsorbed by the terminal buttons of the presynaptic neuron’s axon (pull neurotransmitters back in)

Enzyme deactivation

Neurotransmitters are destroyed(if theres to much) by enzymes in the synapse

Acetylcholine(ACh)

Involved in motor control, attention, learning and memory.

Alzhemier’s - deterioration of ACh producing neurons

Glutamate

Excitatory(increases activation), involved in information transmission.

If to much is produced you might experience seizures

GABA

Inhibitory(slows activity), calms things down.

Stops panic attacks

Dopamine(DA)

Regulates motor behavior, motivation, pleasure, and emotional arousal.

To much dopamine - Schizophrenia

Not enough dopamine - Parkinson’s disease

Norepinephrine(NE)

Influences mood and arousal

Serotonin(5-HT)

Involved in the regulation of sleep and wakefulness, eating, and aggressive behaviour - most antidepressants stop reuptake of serotonin

Endorphins

Chemicals that act within the pain pathways and emotion centers of the brain

Agonists

Drugs that increase the action of a neurotransmitter

-binding will activate the neurotransmitter

Antagonist

Drugs that block(decrease) the function of a neurotransmitter

-binding blocks the action of the neurotranmitter

L-Dopa - Agonist for dopamine

Causes neurons to produce more dopamine

Treatment for Parkinson’s Disease

Amphetamine and Cocaine

Stimulates the release and prevents the reuptake of norepinephrine and dopamine - causing euphoria, wakefulness and burst of energy, produces depression and cravings.

long term use - need more to get the same high because receptor sites are being damaged

Two major divisions of the nervous system

1. Central Nervous System(CNS) - composed of the brain and the spinal cord

2. Peripheral Nervous System(PNS) - connects the CNS to the bodies organs and muscles

Somatic nervous system

A set of nerves that conveys information into and out of the central nervous system

Autonomic nervous system

A set of nerves that carries involuntary and automatic commands that control blood vessels, body organs and glands.

Subdivisions of the autonomic nervous system

1. Sympathetic nervous system - Prepares the body for action in threatening situations - Anxiety, fear, sweating

2. Parasympathetic nervous system - Helps the body return to a normal resting state - Calms you down afterwards

Spinal reflexes

Simple pathways in the nervous system that rapidly generate muscle contractions - if you get burnt, doesn’t go to the brain

Three primary parts of the brain

1. Hindbrain

2. Midbrain

3. Forebrain

The Hindbrain

Continuous with the spinal cord, coordinates information coming into and out of the spinal cord: controls respiration, alertness, motor skills.

Damage will mostly likely cause death

Structures that make up the Hindbrain

1. Medulla - extension of the spinal cord into the skull that coordinates heart rate, circulation and respiration

2. Pons - Relays information from the cerebellum to the rest of the brain (Bridge)

3. Controls fine motor skills

The Midbrain

Main structures:

1. The tectum - orients an organism in the environment, receives stimulus from the eyes ears and kin and moves the organism in a coordinated way towards the stimulus (if you see yummy food)

2. The tegmentum - involved in movement and arousal (if an animal sees a mate)

The forebrain - What makes you human

Highest level of the brain controls complex cognitive, emotional, sensory and motor function.

Main sections:

1. The cerebral cortex

2. The subcortical structures - thalamus, hypothalamus, hippocampus, amygdala, basal ganglia, striatum

Thalamus

Relays and filters information from the senses and transmits the information to the cerebral cortex, receives information from all senses except smell, also filters information.

Thalamic syndrome - severe pain, extreme , sensitivity to touch

Hypothalamus

Regulates body temperature, thirst, hunger, and sexual behaviour.

Damage can cause overeating or lack of interest in food, aggressive behavior or intense pleasure

Hippocampus

Creates new memories and integrating them so that they can be stored.

Damage can lead to short term memory

Amygdala

Crucial for many emotional processes, formation of emotional memories, attaches significance to previously neutral events that are associated with fear, punishment or reward. Amygdala stimulates the hippocampus.

Highly implicated in anxiety

Basal Ganglia

Directs intentional movements - receives input from the cerebral cortex and sends output to the motor centres

Striatum

Controls posture and movement.

Parkinson’s - depletion of dopamine in the striatum

Pituitary gland

The master gland - releases hormones that direct the functions of many other glands in the body.

Cerebral cortex

Responsible for perception emotion movement and thought

Gyri

Raised smooth parts - bumps

Sulci

Indentations or fissures - space between

Contralateral control

Each hemisphere controls functions on the opposite side of the body

Corpus Callosum

Connects the hemispheres of the brain, supports communication of information across hemispheres. Also connected by bundles of axons - commissures

Organization within hemispheres

1. Occipital lobe

2. Parietal lobe

3. Temporal lobe

4. Frontal lobe

Occipital lobe

Processes visual information:

1. Sensory receptors in eyes send info to the thalamus

2. Simple features of stimulus are extracted

3. Processed into a ‘map’ of the stimulus onto the occipital cortex

Damage will cause blindness

Parietal lobe

Processes information about touch. Contains both the somatosensory cortex and the motor cortex(initiates voluntary movement)

Temporal lobe

Responsible for hearing and language:

Primary auditory cortex - receives sensory information from the ears based on the frequencies of sounds

Visual association areas - interpret the meaning of visual stimuli (helps recognize objects)

Frontal lobe

Specialized areas for movement, abstract thinking, planning, memory and judgment - Executive function such as higher order planning, reasoning, inhibition.

Contains dopamine sensitive neurons

Brain plasticity

The brain can adapt to change in sensory input - higher levels of input can result in more allocation to the area receiving input. More plastic when we’re younger

Phantom limb syndrome

After limb amputation, some patients continue to feel sensations where the missing limb would be.

Treatment: Mirror box

Split brain procedure - preformed because of seizures

In split brain patients information presented to the left hemisphere can be described verbally, information presented to the right hemisphere cannot.

Wada test - Intracarotid sodium amobarbital procedure(ISAP)

Used to establish which hemisphere holds language prior to surgery

Hemispatial neglect

After a stroke in the right hemisphere - causes lack of awareness/attention to the left side of the body - patients are unaware they have a problem

Brain imaging

1. Structural brain imaging - basic structure of the brain - allows clinicians or researchers to see abnormalities in brain structure

2. Functional brain imaging - activity of the brain when people perform various kinds of cognitive or motor tasks

Computerized axial tomography (CT) scan

Series of x-ray photos from different angles of the head - shows difference in density of tissue.

Used to locate tumors

Magnetic resonance imaging (MRI)

Brief magnetic pules are applied to the head and absorption through the brain is recorded. Differently charged molecules respond differently revealing structures with different molecular composition. Better resolution than CT scan

Diffusion tensor imaging

Type of MRI used to visualize white matter pathways - maps the connectivity of the human brain

Electroencephalograph (EEG)

Records electrical activity in the brain, in synapse and action potentials - different cognitive processes are associated with different forms of electricalactivity.

Neurofeedback

Real time display of brain activity to try and teach self-regulation of brain function

Positron emission tomography(PET)

A radioactive substance is injected into bloodstream and brain is scanned by radiation detectors

Functional magnetic resonance imaging(fMRI)

Detects oxygenated hemoglobin in the blood and provides an image of the level of activation in each brain area - more time sensitive than PET

Transcranial magnetic stimulation(TMS)

Delivers a magnetic pulse that passes through the skull and briefly deactivates neurons in the cerebral cortex. A major breakthrough in establishing causality in the brain.