Psyc Chapters 1-4

Neuroscience

Study of how nerves and cells send / receive info from the brain, body, and spinal cord

Nervous System

Network of neurons that runs throughout your brain and body

Neurons

Cellular building blocks of the brain

Collection of neurons

Nerves

3 Classes of Nerves

• Motor

• Sensory

• Interneuron

Spinal Cord

Bundle of nerves that connects your body to your brain

Motor Neurons

Send messages to whole body, enabling you to interact w/ your environment

Sensory Neurons

Carry info from within your body and the outside world back to your brain

Interneurons

Connects other neurons and interpret, store, and retrieve info abt the world—allows informed decisions before acting

Central Nervous System (CNS)

Composed of brain and spinal cord—exchanges info between brain and body

Peripheral Nervous System (PNS)

Composed of the sensory and motor nerves that travel throughout your entire body

Somatic Nervous System (sns)

External sensations, voluntary commands — includes skeletal muscles

Autonmic Nervous System (ANS)

Internal sensations—involuntary commands — includes organs, blood vessels, and glands

Sympathetic Nervous System (ANS)

Mobilizes energy (fight-or-flight)

Parasympathetic Nervous System (ANS)

Returns body to resting state (rest-and-digest)

Endocrine System

Network of glands that release hormones into the bloodstream — helps regulate body’s activities and biological states

Adrenal Glands (endocrine system)

Located on top or kidneys, activated by sympathetic branch of ANS, releases adrenaline / cortisol

Pituitary Gland (endocrine system)

Master gland—sends messages to regulate other glands + releases oxytocin

Gut-Brain Axis

Gut’s microorganisms also affect the brain — evidence that people with positive vs. negative outlooks differ in species of microbiota found in their gut

Brain is Organized Into

Forebrain, midbrain, hindbrain + hemispheres (halves), subdivisions (lobes)

Cerebral Cortex

Supports cognitive skills, emotions, and complex mental activity — large and highly developed

Neocortex

Supports complex functions (eg. language, thought, etc)

Occipital Lobe

Vision—contains primary visual cortex

Temporal Lobe

Auditory — contains primary auditory cortex, responsible for language and recognition of people + objects

Parietal Lobe

Contains primary somatosensory cortex—map of body’s skin surface and sense of touch; allows us to pay attention to / locate object

Frontal Lobe

Movement + planning—contains primary motor cortex and prefrontal cortex

(hidden) Insular Lobe

Insulated by overlying cortex, allows us to perceive the inside of our bodes—includes primary taste cortex

Primary Sensory Area

First region to receive signals from its associated sensory nerves

Primary Motor Cortex

Responsible for voluntary movements

Association Cortex

Integrates info from senses + existing knowledge to produce meaningful experience of the world and how to navigate it

Limbic System

Bridges complex mental functions w/ basic mental functions—regulates emotions, smell, learning, memory, and motivation

Hippocampus

Located in temporal lobe—memory + navigating environment

Amygdala

Dedicated to emotion—one of the most interconnected regions of the brain

Basal Ganglia

Planning + executing movement—sends signals to your muscles to act; critical for starting / stopping movement

Thalamus

Central subcortical hub for the signals it receives from all the sensory systems except smell—relays info to / from cerebral cortex

Hypothalamus

Major interface btwn brain and body, integrating internal bodily signals w/ their associated feelings and behaviours

Brainstem

Ensures brain gets oxygen, regulates vital functions, collections sensory signals from body and sends down to create movement (including emotion-related changes)

Midbrain

Includes tegmentum (reflex-driven movement), ventral tegmental area (motivation to move), and substantia nigra (regulates movement)

Hindbrain

Contains pons, medulla oblongata, reticular formation, and cerebellum

Pons

Controls breathing, relays sensations to cortex and subcortex

Medulla Oblongata

Controls autonomic functions and critical reflexes

Reticular Formation

Arousal + attention — regulates sleep and wakefulness (role in ADHD and Alzheimer’s)

Cerebellum

“Little brain” — coordination, precision, balance, and accurate timing; adjusts eye / head movements to facilitate balance

Where are “you” in your brain?

Distributed throughout the association cortices, specifically frontal lobe of neocortex and the regions that hold memories / knowledge / personal traits

Executive Functions

Planning, demonstrating inhibitory control, focusing attention, and organizing mutliple tasks — associated w/ function of prefrontal cortex

Hemispheric Specialization (lateralization)

One-sidedness—one hemisphere being dominant for a process

Corpus Callosum

Relays neural info between the two hemispheres

Contralateral Control

One side of body connected to / controlled by the opposite hemisphere

Interhemispheric Transfer

Rapid exchanged of info between the two hemispheres

Split-Brain Procedures

Severing of corpus callosum to reduce the spread of brain seizures across hemispheres—leads to one hemisphere knowing info the other side does not

Computerized Tomography Scan (CAT scan)

Combines series of x-ray images to reveal 3D structure—low resolution + expose to radiation

Magnetic Resonance Imaging (MRI)

Uses magnetic fields and radio waves—creates images but no info about cell’s functioning / activity

Diffusion Tensor Imaging (DTI)

Variation of MRI that allows assessment of size / direction of the connections between regions

Phrenology

Pseudoscience of idea that abilities / personality traits can be read by measuring bumps on skull—gave rise to idea that distinct regions support distinct mental functions

Neuropsychology

Studies brain’s workings by examining its altered function following brain damage

Lesion

Abnormal tissue resulting from disease / trauma / surgical intervention

Dissociation

Evidence following lesion that a specific area is involved in a particular function but not in others

Double Dissociation

Two structures have highly distinct functions

Single-Cell Recordings

Measurement of the electrical activity of a single neuron

Electroencephalography (EEG)

Recording of electrical waves from thousands of neurons—gathered using electrodes placed on the scalp to diagnose brain states—can be averaged to reveal an event-related potential

Magnetoencephalography (MEG)

Records magnetic fields produced by the brain’s electrical currents—provide insight into how different parts of the brain communicate

Positron Emission Tomography (PET scan)

Inject radioactive glucose into bloodstream, revealing regions of higher brain activity—can provide insight into brain’s use of specific neurochemicals, but not an exact measurement of the time between stimulus and response

Functional Magnetic Resonance Imaging (fMRI)

Use of many MRI scans in sequence to track oxygen flowing through the brain—reveals how the magnetic properties of blood that contain oxygen differ from the properties that have consumed oxygen

Limitations of fMRI

• Difficult to establish that brain activity in a region is causally related to mental events / behaviour

• Need to turn “off” and “on” a portion of the brain and see if ability disappears and reappears

Deep Brain Stimulation (DBS)

Insert electrodes deep into brain to alter activity of regions that have been abnormally active

Transcranial Magnetic Stimulation (TMS)

Creates a temporary and reversible disruption / enhancement of cortical brain function—induces an electrical current to temporarily change the patterns of normal brain activity

Transcranial Direct Current Stimulation (TDCS)

Low levels of direct current delivered via electrodes on the head to stimulate brain

Dendrites

Receive chemical messages from other neurons

Soma (cell body)

Collects neural impulses, contains nucleus, and provides life-sustaining functions for cell

Axon

Transports electrical impulses to other neurons

Terminal Branches

Convert electrical impulses into chemical messages to other neurons

Myelin Sheath

Layer of fatty tissue covering the axon—ensures signal moves quickly with less resistance + gives brain’s white matter its light appearance

Demyelination

Degradation of myelin—characteristic of neurodegenerative disease

Glia (what Myelin is made up of)

Insulate, support, and nourish neurons—remove debris, serve as cellular glue, contribute to info processing during childhood development, helps support axon growth, and aids in formation of neural networks

Action Potential

Change in voltage created by a neuron that serves the basis for neural signalling—wave of change in electrical potential that rushes down the axon, measured using single-cell recording

Electricity in neurons is created by…

Chemistry

Extracellular Fluid

What neurons are bathed in—composed of ions → Na⁺, Cl^-, K⁺, Ca²⁺

Resting Potential

Different chemical []s of ions inside vs. outside results in negative voltage

Ion channels open when

other neurons sufficiently stimulate a neuron’s dendrites—allows cations (Na⁺) into neuron causing a chain reaction moving down the axon

Depolarization

Increase in cations into neural—moves negative resting potential toward zero

Passing the Voltage Threshold

Causes voltage-controlled ion channels to open, allowing cations to flood in (neuron’s voltage becomes more positive as it passes zero)—results in a series of APs that carry the signal down the axon

Repolarization

Portion of the AP where the neuron returns to the resting potential

Refractory Period

Time required for the neuron to return to its resting state before it can fire another AP

Excitatory Messages

Move the voltage of the neuron closer to the threshold—positive messages

Inhibitory Messages

Move the voltage of the neuron farther from the threshold—negative messages

Is Action Potential good for communicating info within or between neurons?

Within

Synapse

gap where sending neuron (presynaptic) communicates with dendrites / cell body of the receiving neuron (postsynaptic)

Neurotransmitters (NTs)

Chemical messengers released at terminal branch to allow communication btwn neurons

Lock-and-Key Specificity

Target neurons have receptors that recognize and bind with specific NTs

What happens once a neurotransmitter binds to its receptor?

Ion channels open → changes in ion flow → generates electrical signal

Diffusion

NTs drift out of synapse over time into larger extracellular space

Degradation

Chemical reaction breaks down NTs in synapse

Reuptake

NTs reabsorbed into presynaptic terminal branches

3 Major Classes of NTs

Amino Acids, Monoamines, Acetylcholine

Amino Acids

Glutamate (excitatory, involved w/ memory), GABA (inhibitory, involved w/ muscle tone)

Monoamines

norepinephrine (adrenaline, fight-or-glight, dopamine (too much = shizophrenia, too little = Parkinson’s), serotonin (low = depression, high = hallucinogenic effects))

Acetylcholine

Inhibitory and excitatory, supports heart and skeletal muscle, cognitive function (low = muscular dystrophy, dementia of Alzheimer’s)

Psychoactive Drugs

Artificial chemicals, behave same way as NT (existing infrastructure) — include prescriptive and recreational drugs, and psychoactive compounds (caffeine, nicotine, alcohol)

Endorphins

class of NTs — body’s natural opioids, produced during pain, inhibit transmission of pain signals, “feel-good” chemicals that are recognized by + bind w/ opiate receptors in brain

Opioids

Psychoactive drugs prescribed as analgesics to relieve pain — mimic endorphins