PSYC102: CH3 - Biological Psychology

Neuron

Nerve cells specialized for communication

• 85 billion of them in the brain with 160 trillion connects

• Obey the “all or none” law: They either fire or they don’t

Dendrites

Portion of neuron that receives signals from other neurons and pass them on to the cell body

Cell Body/Soma

Manufactures new cell components and materials needed by the neuron. Contains nucleus and genetic material

Axon

Portion of the neuron that sends signals

Axon Hillock

Part of the neuron where the cell body connects to the axon; it integrates incoming signals and is the point where an action potential is generated if the signal is strong enough.

Axon Terminal/Terminal Button

Where the electrical message is changed to a chemical signal using neurotransmitters to communicate with another neuron or target cell. It sends them signals by releasing neurotransmitters into the synapse.

Acts as the “messenger” delivering the signal across the synapse.

Synaptic Vesicle

Spherical sac containing neurotransmitters that travel the full length of the axon to the axon terminal, where it bursts, releasing the neurotransmitters

Neurotransmitter

Chemical messengers that allow neurons to communicate

Synapse

Space between two connecting neurons (terminal buttons of one dendritic spines of another) through which messages are transmitted chemically

• Neurons communicate across it using neurotransmitters, which are released by the action potential reaching the terminal button

Synaptic Cleft

A gap into which neurotransmitters are released from the axon terminal

Glial Cell

Cell in the central nervous system that plays a role in:

• the formation of myelin for neurons (oligodendrocytes) and

• the blood-brain barrier (astrocytes),

• clean away debris after injury (microglial cells)

• Maybe enhances learning and memory?

Ratio to Neurons: 1:1

Myelin Sheath

Glial cells wrapped around axons that act as insulators of the neuron’s signal so they don’t become scrambled

Nodes of Ranvier

Small gaps between segments of the myelin sheath on a neuron’s axon that help speed up the transmission of nerve impulses by allowing the electrical impulses to leap and go faster (preventing info loss)

Resting Potential

Electrical charge difference (-60 millivolts) across the neuronal membrane when the neuron is not being stimulated or inhibited

When there are no neurotransmitters acting on the neuron

Baseline state: neuron isnt doing much of anything, there are more negative particles inside than outside

While at rest, particles of both types are flowing in and out of the membrane.

Threshold

Membrane potential necessary to trigger an action potential

When the electrical charge inside the neuron reaches a high enough level relative to the outside, called the _______, an electrical impulse called an action potential is triggered

Action potential

How neurons communicate, abrupt waves of electrical discharge triggered by a massive change in charge inside the axon. When this occurs, the neuron fires.

Positively charged particles flow rapidly into the axon then flow out just as rapidly, causing a dramatic and sudden spoke in positive charge followed by a dramatic and sudden decrease in charge, with the inside charge ending up at a slightly more more negative than its original resting value. These radical shifts produce a release of electricity. Which then reaches the axon terminal.

Electrical impulse that travels down the axon triggering the release of neurotransmitters

• Does not vary in strength, but does vary in frequency

Absolute refractory period

Time during which another action potential is impossible; limits the maximal firing rate

Receptor site

Location along dendrites that uniquely recognizes a neurotransmitter

Reuptake

Means recycling of neurotransmitters. They are released from receptors and go back into the axon terminal, a continually occurring process by which the synaptic vesicle reabsorbs the neurotransmitter.

• Ex. Like letting some liquid drip out of the bottom of a straw and then sucking it back up again.

Plasticity

The ability of the nervous system to change, an axon can break connection and connect to another set of dendrites

Neurogenesis

Creation of new neurons in the adult brain

Stem cell

A cell, often originating in embryos, having the capacity to differentiate into a more specialized cell

Central Nervous System

Part of nervous system containing the brain and spinal cord that controls the mind and behaviour

• Command center; integrates information (deals with a lot of sensory info)

Peripheral Nervous System

Nerves in the body that extend outside the CNS

Cerebral cortex

Outmost part of the forebrain, responsible for analyzing sensory processing and higher brain functions

The Cerebrum/Forebrain

Forward part of the brain that allows advanced intellectual abilities

• Most highly developed area of the human brain

• Consists of 2 hemispheres, which communicate and cooperate

• Includes most of the limbic system, basal ganglia, olfactory bulb, and cerebral cortex

Cerebral Hemispheres

Two halves of the cerebral cortex, each of which serve distinct yet highly integrated functions

Corpus Callosum

Large band of fibers connecting the two cerebral left and right hemispheres

Frontal lobes

Forward part of cerebral cortex responsible for motor function (movement), language, memory, and planning

• Oversee and organizes most other brain functions (a process called executive functioning)

Motor Cortex

Part of frontal lobe responsible for body movement

Prefrontal Cortex

Part of frontal lobe responsible for thinking, planning, personality, mood, self-awareness, decision making, executive functions, and language

• In front of the motor cortex

• Damage to this region often boosts people’s risk for impulsive or even criminal behaviours

Broca’s area

Language area in the prefrontal cortex that helps to control speech/language production

Parietal Lobe

Upper middle part of the cerebral cortex lying behind the frontal lobe that’s specialized for touch and perception

Temporal lobe

Lower part of cerebral cortex that plays roles in hearing, understanding language, and memory

Wernicke’s area

Part of the temporal love involved in understanding speech and language

Occipital lobe

Back part of cerebral cortex specialized for vision

Primary sensory cortex

Regions of the cerebral cortex that integrate simpler functions to perform more complex functions

Basal Ganglia

Structures in the forebrain that help to control movement and motor planning

• Damage results in Parkinson’s: lack of control over movement and uncontrollable tremors. Tourette’s

• Complex structures, much unknown

• Activates before voluntary movement: action selection, motor preparation, timing, task switching

Limbic system

Emotional center of brain that also plays roles in smell, motivation, and memory

• Processes information about our internal states such as BP, Heart, Respiration, perspiration

Thalamus

Gateway from the sense organs to the primary sensory cortex, conveys sensory information to cortex

• Contains many areas, each of which connects to a specific region of the cerebral cortex

• The “sensory relay station,” it passes through it, goes through initial processing, before traveling to the cortex.

Hypothalamus

Part of the brain responsible for maintaining a constant internal bodily state

• Oversees endocrine and autonomic nervous system

• Key psychological drivers, regulating hunger, thirst, sexual motivation, temperature, other emotional behaviors

• “The Four F’s: feeding, fighting, fleeing, sexual activity

Amygdala

Part of limbic system that plays key roles in fear, excitement, and arousal

• Also plays role in fear conditioning, predicting when something scary is about to happen

Hippocampus

Part of the brain that plays a role in memory, especially spatial memory— the memory of the physical layout of things in our environment

• When we make a mental map of how to get from one place to another

• Damage leads to problems forming new memories, but leaves old ones in tact

Cerebellum

Brain structure responsible for our sense of balance

Brain stem

Part of the brain between the spinal cord and cerebral cortex that contains the:

• midbrain: tracks visual stimuli and reflexes triggered by sounds, contributes to movement

• pons: conveys sensory information between the cortex and cerebellum

• and medulla: regulates breathing and heartbeats

Midbrain

Part of the brain stem that contributes to movement, tracking of visual stimuli, and reflexes triggered by sound

Spinal Cord

Thick bundle of nerves that conveys information between the brain and the rest of the body

Interneuron

Neuron that sends messages to other neurons nearby

Reflex

An automatic motor response to a sensory stimulus

The Somatic Nervous System

Part of the nervous system that conveys information between the central nervous system and the body, controlling and coordinating voluntary movement

• Walking, reaching, grasping

The Autonomic Nervous System

Part of the nervous system controlling the involuntary actions of our internal organs and glands, which (along with the limbic system) participates in emotion regulation

Sympathetic Nervous System

Division of the autonomic nervous system engaged during a emotional arousal and crisis or after actions requiring fight or flight

• Neurons fire together (“in sympathy’)

Parasympathetic Nervous System

Division of the autonomic nervous system that controls rest, slows heart rate, and digestion

• Works in opposition to sympathetic to maintain homeostasis

electroencephalograph (EEG)

recording of brain’s electrical activity at the surface of the skull

Computerized Tomography

a scanning technique using multiple X-rays to construct three-dimensional images

Magnetic Resonance Imaging

technique that uses magnetic fields to indirectly visualize brain structure

• Measures distribution of hydrogen atoms, which are released because of the magnetic field

Positron Emission Tomography

imaging technique that measures consumption of glucose-like molecules, yielding a picture of neural actiXity in different reIions of tJe brain

• Isotope that attaches to glucose

• Poor Temporal resolution: relies on blood

• Good Spatial resolution

Functional Magnetic Resonance Imaging

technique that uses magnetic fields to visualize brain activity using changes in blood oxygen level

• Good spatial resolution

• Good temporal resolution

Transcranial Magnetic Stimulation

technique that applies strong and quickly changing magnetic fields to the surface of the skull that can either enhance or interrupt brain function

Magnetoencephalography (MEG)

technique that measures brain activity by detecting tiny magnetic fields generated by the brain

• high temporal resolution

• Glutamate & GABA

• • Main excitatory neurotransmitter

  • Function: Increases likelihood that neurons will fire

  • Role in: Learning and memory

• • Main inhibitory neurotransmitter

  • Function: Dampens neural activity

  • Role in: Learning, memory, sleep

Acetylcholine

• Functions: Arousal, selective attention, memory, sleep

Monoamines (contain 1 amino acid)

• Dopamine

  • Pleasure, reward, goal-seeking

  • Activated by: Food, sex, humour, gambling

•  Norepinephrine, Serotonin

  • Regulate arousal and response to stimuli

• Anandamide

• Binds to same receptors as THC v

• Eating, motivation, memory, sleep

Neuropeptides

• Short chains of amino acids; act like neurotransmitters but are more specialized

• Endorphins: Chemical in the brain that plays a specialized role in pain reduction

• Other neuropeptides: Regulate hunger, satiety, learning, and memory.