PSYC110 Final Exam Study Guide Notes

Lectures 1-2

Lecture One: Reticular Theory vs. Neuron Doctrine

Reticular Theory: Neurites of different neurons are fused together to form a continuous reticulum.
- Associated with Camillo Golgi (1843-1926).
Neuron Doctrine: Neurons are separate cells and communicate by contact.
- Associated with Santiago Ramon y Cajal (1852-1934).

Number of Neurons in the Human Brain

The human brain has 86 billion neurons.

Parts of the Neuron

Soma: The cell body.
Nucleus: Contains genetic material.
Dendrites: Receive messages from other cells.
Axon Hillock: Integrates all messages in the neuron and initiates action potentials.
Axons: Passes messages away from the cell body to other neurons, muscles, or glands; a wire that sends information over great distances.
Axon Terminals: Form junctions with other cells.
Terminal Button: The axon terminal containing synaptic vesicles.
Myelin Sheath: Covers the axon of some neurons and helps speed neural impulses.

Glial Cells

Myelin: Layers of membrane to insulate axons.
Astrocytes: The most numerous glial cell in the brain.
- Removes neurotransmitters from the synaptic cleft.
- Has their own receptors.
- Secrete proteins that help neurons form connections.
Microglia: Cleans up cellular debris produced by damage (also known as phagocytes).

Central Nervous System vs. Peripheral Nervous System

Central Nervous System:
- Brain
- Spinal cord
Peripheral Nervous System:
- Peripheral motor and sensory nerves
- Somatic Nervous System: Relays sensory and motor information to and from the CNS.
- Autonomic Nervous System: Controls our internal organs and glands and can be divided into the sympathetic and parasympathetic nervous systems.
  - Sympathetic Nervous System: Fight or flight response.
  - Parasympathetic Nervous System: Rest and digest.

Gray Matter vs. White Matter

Gray Matter: Contains the cell bodies (the somas) in the central nervous system.
White Matter: Contains all the axons that run to and from the neurons.

Meninges and Cerebrospinal Fluid

Dura Mater: The tough mother - tough, flexible outermost meninx.
Arachnoid Mater: Middle layer, looks like spider webs.
Pia Mater: The tender mother - delicate, innermost layer.
Cerebrospinal Fluid: A filtrate of blood plasma, provides nourishment, removes waste, and protects the brain.

Ventricles

Lateral Ventricles: Paired, C-shaped cavities within the brain's cerebral hemispheres, part of the ventricular system, responsible for producing and circulating cerebrospinal fluid (CSF).
Third Ventricle: A narrow, midline cavity in the brain, specifically part of the diencephalon, that is part of the ventricular system responsible for producing, transporting, and removing cerebrospinal fluid.
Cerebral Aqueduct: A narrow canal within the midbrain that connects the third and fourth ventricles, facilitating the flow of cerebrospinal fluid (CSF).
Fourth Ventricle: A fluid-filled cavity within the brain, specifically located in the hindbrain, that plays a crucial role in the production, circulation, and absorption of cerebrospinal fluid (CSF), which is essential for brain protection and function.
Choroid Plexus: A network of specialized cells and capillaries within the brain's ventricles that plays a crucial role in producing cerebrospinal fluid (CSF), which bathes and protects the brain and spinal cord.

Dorsal vs. Ventral Horn/Root (Gray Matter)

Dorsal Horn/Root: Information is coming in from sensory pathways of the peripheral nervous system.
Ventral Horn/Root: Information is going out to motor pathways of the peripheral nervous system.

Directions

Anterior: Towards the front.
Posterior: Towards the back.
Superior: Dorsal or rostral.
Inferior: Ventral or caudal.

Sections

Coronal: Divides the brain into an anterior and posterior portion.
Horizontal: Divides the brain into a superior and inferior portion.
Sagittal: A vertical anatomical plane that divides the body (or brain) into left and right sections.

Lobes

Frontal Lobe: Thinking + movement.
Parietal Lobe: Sensation.
Temporal Lobe: Audition + learning, and memory.
Occipital Lobe: Vision.

Forebrain

Motor Cortex (Homunculus): A region of the frontal lobe responsible for planning, controlling, and executing voluntary movements, including skilled movements and motor learning.
Somatosensory Cortex (Homunculus): A region of the brain's parietal lobe that receives and processes sensory information from the body, including touch, temperature, pain, and proprioception (body position).
Primary Visual Cortex: A brain region in the occipital lobe that receives, integrates, and processes visual information from the retinas, forming the foundation of our visual perception.
Primary Auditory Cortex: A brain region in the occipital lobe that receives, integrates, and processes auditory information from the ears, forming the foundation of our auditory perception.
Corpus Callosum: A large, C-shaped bundle of nerve fibers (white matter) that connects the two cerebral hemispheres (left and right sides of the brain), facilitating communication and coordination between them.
Basal Ganglia: A group of interconnected brain structures primarily involved in motor control, but also playing roles in cognitive functions, emotional processing, and reward-motivated behavior.

Laterality of the Brain

The specialization of functions between the brain's two hemispheres, with the left hemisphere often associated with logic and language, and the right with creativity and spatial reasoning.
No one is truly left or right brained; we always use both hemispheres.

Limbic Structures

Amygdala: An almond-shaped structure in the brain's temporal lobe, part of the limbic system, primarily associated with processing emotions, particularly fear, and plays a crucial role in emotional memory and behavior.
Hippocampus: A seahorse-shaped region of the brain that plays a crucial role in memory and learning.
Thalamus: A large, egg-shaped structure located deep within the brain, plays a crucial role in sensory processing, motor control, consciousness and arousal, emotion, and cognition.
Hypothalamus: A brain region crucial for maintaining homeostasis, regulating autonomic functions, and influencing behaviors like appetite, thirst, sleep, and sexual activity.

Midbrain Structures

Tectum: The dorsal (rear) part of the midbrain, primarily responsible for auditory and visual reflexes, and includes the superior and inferior colliculi.
Tegmentum: The ventral portion of the midbrain that serves as an important relay center for sensory and motor information.

Hindbrain Structures

Cerebellum: A brain region primarily responsible for coordinating voluntary muscle movements, maintaining posture, balance, and motor learning, though it also plays a role in cognitive functions - “little brain”.
Pons: A part of your brainstem which links your brain to your spinal cord, plays a crucial role in relaying signals between the brain and spinal cord, and is involved in regulating breathing, sleep-wake cycles, and sensory functions like hearing, taste, and balance.
Medulla Oblongata: The most caudal part of the brainstem, located at the base of the brain where it connects to the spinal cord, and is crucial for regulating vital, involuntary functions like breathing, heart rate, and blood pressure.

Lecture Two

Resting Membrane Potential: The inside of the cell is more negative ( $-65mV$ ) compared to the outside.
Potential: The separation of electrical charge across the membrane – it has the potential to be excitable.
At Rest: The cell is not generating impulses.

Ions

Sodium (Na+) Ions: Positively charged sodium ( $Na+$ ) ions are attracted to the negative charge inside the cell; more highly concentrated outside the cell in the extracellular fluid.
- $Na+$ ions flow into the cell and depolarize it, making the inside of the cell positive, leading to an action potential.
Potassium (K+) Ions: Positively charged ions that play a crucial role in the resting membrane potential of neurons and the transmission of nerve signals; more highly concentrated near the membrane in intracellular fluid.
Chloride (Cl-) Ions: Negatively charged ions that play a crucial role in neuronal signaling by regulating membrane potential and excitability; evenly distributed.

Ion Channels

Specialized membrane proteins that facilitate the selective passage of ions across cell membranes.

Action Potentials

Stimulus: Affects the neuron; initiates the rapid electrical signal that neurons use to transmit information.
Threshold: The critical level of membrane depolarization that a neuron's membrane potential must reach to initiate an action potential.
Rising Phase (Depolarization): The cell is more +++ until it reaches the threshold.
Peak: The highest point of electrical charge (depolarization) within a neuron.
Falling Phase (Repolarization): The cell becomes less and less positive.
Hyperpolarization: The cell is too negative.
Resting State: A neuron's state when it's not actively transmitting signals, characterized by a stable, negative membrane potential (around $-70mV$ ).

Saltatory Conduction

Action potentials travel down the axon.
Myelin Sheath: Covers the axon of some neurons and helps speed neural impulses.

Chemical Synapse

Synaptic Vesicles & Terminal Button: The presynaptic neuron stores neurotransmitter in synaptic vesicles at the terminal button, waiting to be released when an action potential (AP) reaches the presynaptic terminal.
Synapse: The junction between the axon of one neuron and the dendrite of another, through which the two neurons communicate; at the axon terminal button.
Receptors: Specialized cells or proteins that detect and respond to specific stimuli in the environment or within the body.
Reuptake: Moving a neurotransmitter from the synapse back into the axon terminal from which it was released.

Presynaptic and Postsynaptic Cells

Presynaptic: A neuron that transmits signals to another neuron (the postsynaptic cell) across a synapse by releasing neurotransmitters.
Postsynaptic Cell: The cell that receives a signal from a presynaptic cell across a synapse.
Both separated by the synapse.

Electrical Synapses

Connexon: A specialized connection between two neurons that allows for direct and rapid electrical signaling via the passage of ions and small molecules through channels.
Ions: Flow directly between neurons through gap junctions, facilitating a rapid and direct transfer of electrical signals.

Lectures 3-6

Lecture 3 – Neurodevelopment

Early Divisions of the Embryonic Brain (4 weeks)

Prosencephalon (forebrain)
- telencephalon – cerebral hemispheres
- diencephalon – thalamus, hypothalamus, etc.
Mesencephalon (midbrain)
- remains as midbrain structures
Rhombencephalon (hindbrain)
- metencephalon – cerebellum + pons
- myelencephalon – medulla

Neurulation – Neural Tube

The creation of the neural tube (and neural crest) happens approximately 24 days after conception.

Symmetrical and Asymmetrical Cell Division

Symmetrical: produces two identical progenitor cells (increases cell number) + creates the ventricular (VZ) and subventricular zones (SVZ)
Asymmetrical: produces one progenitor and one brain cell, differentiation begins

Neural Migration and Passive Cell Displacement

Neural migration: New neurons migrate along the radial glia to their place as newer cells push older ones outward.
- “climbing” creates structures farther away
Cell displacement: new cells push previously formed cells out of the proliferation zone in VZ or SVZ toward the place where they need to migrate pushing out creates structures closer

Timeline

neurulation — creation of neural tube
Neuronal proliferation: creation of neurons
Neural migration: movement of neurons
Apoptosis: death of neurons
Synaptogenesis: creation of synapses
Myelination: myelin sheath forming on axons
Pruning: death of synapses by apoptosis

Synaptic Plasticity – Neuroplasticity

the ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions, or connections.

Lecture 4 – The Visual System

Sensory Transduction

Process of converting sensory stimuli into coded neural signals specialized for all of our senses

Light: Wavelength, Amplitude

Wavelength – the distance between two peaks of light waves, determines color
Amplitude – the height of the waves, determines brightness.

Anatomy of the Eye

Cornea – the glassy surface that protects the eye, focuses light
Iris – muscles that allow the eye to contract
Pupil – dark opening that allows the light through
Retina – wrapped around the inside of the eye, contains photoreceptors
- back of the eye, part of the brain, detects differences in light intensity
- light gets reflected onto the retina inverted (left right reversed visual field)

Retina

RGCs, Bipolar Cells, Photoreceptors, Fovea
Retinal Ganglion Cells (RGC) – type of neuron located in the retina of the eye, plays a crucial role in vision by transmitting visual information from the eye to the brain.
Bipolar cells – type of neuron in the retina that receive input from photoreceptors (rods and cones + detect light) which then transmit signals to ganglion cells, play a central role in the processing and relay of visual signals.
Photoreceptors – specialized sensory neurons in the retina that detect light and convert it into electrical signals
Fovea – central area of the retina, high acuity, cone-rich, provides the sharpest and most detailed vision

Rods vs. Cones

Rods – high sensitivity to light, low acuity, achromatic, rare in fovea
Cones – low sensitivity to light, high sensitivity to color (red blue green), high-acuity vision, concentrated in the fovea

Phototransduction: Dark Current

Phototransduction – process by which photoreceptor cells (rods and cones) in the retina convert light into electrical signals that can be interpreted by the brain as vision
Dark current – photoreceptors depolarize when they detect the darkness and release glutamate; when light is detected, they hyperpolarize and stop glutamate release

Trichromatic Theory of Color Vision

all colors can be created by combining RBG, human eye perceives color thru activity of three photoreceptors which are each sensitive to specific wavelengths
- long — red
- medium — green
- short — blue

Opponent Process Theory

color is coded in opponent pairs, some cells are excited by one color in the pair, but inhibited by the other (applies to RGC cells in the retina)
- black/white, yellow/blue, green/red

Visual Pathway

RGC from outer halves of retina project to the ipsilateral (same side) of the brain while RGCs from inner side project to contralateral (opposite) side
- light → retina → optic nerve → lateral geniculate nucleus (LGN) → primary visual cortex (V1)
  - LGN: thalamus project via optic radiation to V1
  - 6 layers of neurons with each layer processing diff aspect of the image
    - 1/2 : movement, achromatic
    - 3-6: color sensitive, more sensitive to detail
  - V1 early visual processing

Dorsal Stream vs. Ventral Stream (in the extrastriate cortex)

Dorsal – "where/how" pathway – spatial and motion processing/how one might interact with a visual stimulus
Ventral – "what" pathway – object recognition and identification
Inferior Temporal Cortex: Part of the ventral stream; involved in recognizing visual patterns and identifying objects

Lecture 5 – Hearing

Sound waves

Hertz (Hz) – frequency or pitch
Frequency (wavelength) – represents the pitch of a sound
Amplitude – loudness

Anatomy of the Ear

Outer Ear
- pinna (auricles) — collects sound
Middle Ear
- tympanic membrane (ear drum) — sound hits and moves
- ossicles (smallest bones in body) — move when subjected to auditory input (amplify vibrations); consist of
  1. malleus (hammer)
  2. incus (anvil)
  3. stapes (stirrup)
Inner Ear
- cochlea — fluid filled spiral shape structure divided into 3 fluid filled chamber (scala vestibuli, scala media, scala tympani) where signal transduction occurs, contains organ of Corti
- auditory nerve — transmits signals to brain

Organ of Corti

3 layers – Basilar Membrane, Hair Cells, Tectorial Membrane
When the middle ear interacts with the oval window, it sets up a wave of vibrations in the basilar membrane
Depending on where the basilar membrane flexes, specific hair cells are activated

Basilar Membrane – Place Code Theory

Basilar membrane – thickest and narrowest at the base, thinnest and widest at the apex
- near the base - resonates high frequencies
- near the apex - resonates low frequencies
Place code theory – the location along the spiral corresponds to the sound frequency
tonotopy – map of frequency

Auditory Pathway

cochlea, signal sent out via auditory nerve → nerve connected to hair cells in organ of corti → info enters pons → sent upward to medial geniculate nucleus (MGN) of the thalamus → auditory cortex (A1)
Tonotopic Organization
- Spatial arrangement where different frequencies are processed in specific locations in A1 (primary auditory cortex)

Anterior vs. Posterior Stream

Anterior stream – “what” (sound identity)
Posterior stream – “where” (sound location)

Lecture 6 – Motor Control

Feedback Control vs. Feed-Forward Control

Feedback – the output is monitored by various sensory systems (uses sensory input to adjust movement); the processing of sensory systems is relatively slow - limited to slow movements
Feed-forward – the movement is predicted based on sensory information conditions and memories of past events (walking in snow based on last winter)

Role of the Prefrontal Cortex

Responds to lights, noises and other sensory signals that lead to movement
Calculates predictable outcomes of actions and plans movement according to those outcomes
decision making

Role of the Premotor Cortex

Receives information from the prefrontal cortex, prepares and organizes movements based on external cues
Send info to the primary motor cortex

Role of the Motor Cortex

Executes voluntary movement, controls specific body parts

Sensory and Motor Homunculus

a visual representation of how the somatosensory cortex (postcentral gyrus of parietal lobe) maps sensory input from diff parts of the body
- proportion related richness of innervation of particular body part
- areas of the body w/ more sensory connections are represented larger

Corticospinal Tract

main descending route from motor cortex to spinal cord
- motor cortex → midbrain → medulla (crosses over) → spinal cord → muscles/fibers
  - cross over — opposite-side tract controls movement of opposite side of body
  - same side tract controls movement in middle body (trunk and shoulders)

Dorsal Horn vs. Ventral Horn

motor unit one motor neuron and its associated fibers lecture 1

Motor Unit

One motor neuron and its associated fibers

Henneman’s Size Principle

slow motor neurons — generate low sustained tension + recruited first
fast fatigue-resistant unit — generate more strength (walking/running) + recruited second
fast fatigable units — intense movement but fatigue fast + recruited last
smaller motor units recruited first followed by larger ones for stronger contractions

Neuromuscular Junction

synapse between the terminal buttons of axon (neuron) and muscle fiber
acetylcholine is the key neurotransmitter

Central Pattern Generators

network of neurons that produce rhythmic output by its anatomical and synaptic interactions based on intrinsic properties of its neurons, CPGs generate complex patterned output even if they do not receive any patterned input
gives rise to rhythmic motor activity (walking)
neural circuits in spinal cord that produce rhythmic movements independent of sensory feedback (walking)

Role of the Cerebellum

Associated with balance, coordination, and planning of movement
Receives input from the motor cortex about planned movement
Receives input from the spinal cord about “actual” movement
Compares planned and actual movement to make adjustments
Very important for learning defined motor functions, such as playing a piano

Discussion Section

Corpus Callosum bundle of fibers connecting cerebral hemispheres which enables communication
Limbic System - “emotion system” (lecture 1)
- forms ring or border around brain stem
- emotional processing, memory, motivation
  - cingulate cortex — empathy, emotional pain
  - thalamus — relay station, synchronizes sensory info
  - hypothalamus — homeostasis, hormone control, body temp, thirst, hunger, circadian rhythms, connects to endocrine system
  - hippocampus — learning, spatial memory, memory consolidation
  - amygdala — fear and emotion
  - basal ganglia — movement, habituation, emotions, involved in addictions
Diencephalon
- Composed of the thalamus and hypothalamus; major sensory and homeostatic processing center.
Midbrain (mesencephalon) Structures
- Tectum – control of eye movement
- Tegmentum – motor functions and arousal, includes the substantia nigra and the ventral tegmental area
  - Substantia Nigra – dopamine production, movement control and projects to the motor centers of the basal ganglia
  - Ventral Tegmental Area (VTA) – dopamine production, involved in the reward pathway + projects to the frontal cortex and the nucleus accumbens of the basal ganglia
- Cerebral Aqueduct – connects third and fourth ventricles; CSF flow
Hindbrain
- Cerebellum – movement control, left → right; right → left
- Pons – bridge between medulla and cerebellum, sleep/arousal
- Medulla – autonomic functions (breathing, heart rate, blood pressure)

Lectures 7-8

Lecture 7: Homeostasis

Maslow’s Hierarchy of Needs

self-actualization — all core needs are met, becoming most complete and authentic version of ourselves; free to act as we choose so that we are aligned with our values and higher purpose
self-esteem — once we’re secure in social needs, primal desires for status and self-esteem; want to feel not just part of the group but also an admired/respected part
social — if we feel safe, social needs for loving and belonging; feel secure when we’re part of a tribe we can trust and are unworried abt rejection / alienation
safety — if we feel OK in the exact moment, we want to feel safe; confident we can avoid pain, hunger, other dangers in immediate future
physiological (bottom) — food, water, sleep, warmth, physical health, etc.

Homeostasis

tendency to resist change in order to maintain a stable, relatively constant internal environment
most of our food intake is used to maintain basal metabolic rates (BMR)
- ~55% of energy usage is to maintain body heat and other basic bodily functions (breathing, blood circulation)
- ~33% is used for digestion and extracting nutrients
- ~12-13% is used for active behavior
- exercise can only use up so much of our energy = not the best way to lose weight

Metabolism

converting calories into energy
when digestive tract is empty, we are in the fasting stage
when digestive tract full, we are in the absorptive phase
body stores energy btwn meals in short-term and long-term storage

Short-Term Storage: Glucostatic Theory

glucostatic theory of food control
- glucose main source of energy in body
- set point – level of glucose concentration in the blood influences hunger and satiation → short term appetite control
- glycogen – converted glucose, stored as reserve fuel
- insulin — hormone released by the pancreas that convert glucose into glycogen needed by body to use glucose for energy; high blood glucose
- glucagon — hormone from pancreas that converts glycogen back to glucose; low blood glucose

Long-Term Storage: Lipostatic Theory

lipostatic theory of food control
- long time regulation of weight based on optimum level of body fat
- fat stores low = signals sent to hypothalamus to increase food intake
- fat stores exceed optimal level = signals sent to reduce food intake
- lipids – fatty tissue (adipose tissue) that can be converted into glucose and ketones
- ketone bodies – energy source
  - ketogenesis if body doesn’t have sufficient glucose levels, can convert lipids into ketone bodies and use it as an energy source

Hunger Signals

ghrelin — produced in stomach walls; levels rise when hungry → signals to the hypothalamus to activate Neuropeptide Y which stimulates appetite and decreases metabolism
hypoglycemia (glucoprivation) — a fall in blood glucose levels, detected by the liver → hunger signals to the brain via the vagus nerve
lipoprivation — fall in fatty acid levels, detected by liver → hunger signals to brain via the vagus nerve

Satiety Signals

stretch receptors
- stomach, intestines, and liver contain receptors that detect nutrients and stretch of stomach
- sensory fibers from vagus nerve can detect stretch of stomach based on how full it is → send satiety signals to the brain
leptin
- secreted by fat cells
- high levels signal high fat stores to the hypothalamus → turns off eating and decreases motivation for physical activity
- made by adipose cells
- less leptin before eating; more leptin after eating
- deficiency: leptin receptors reside in arcuate nucleus of hypothalamus along with insulin
- mice expressing recessive gene with leptin deficiency have more body fat than mice that do not express recessive gene

Dual Center Hypothesis

Lateral hypothalamus (LH) regulates hunger
Ventromedial hypothalamus (VMH) regulates satiety
lesion studies show LH lesions reduce eating while VMH lesions increase eating

Arcuate Nucleus of the Hypothalamus

POMC/CART neurons vs. NPY/AgRP neurons
peptides that suppress appetite (anorexigenic)
- pro-opiomelanocortin (POMC)
- cholecystokinin (CCK)
- cocaine-and-amphetamine-regulated transcript (CART)
- promote satiety, reduce feeding
peptides that stimulates appetite (orexigenic)
- agouti-related protein (AGRP)
- neuropeptide Y (NPY)
- orexin
- melanin-concentrating hormone (MCH)
- promotes hunger, increase feeding

Lecture 8: Learning and Memory

Memory Types

sensory memory, short term memory, long term memory
Sensory memory
- few seconds
- George Sperling (1963) showed participants a screen with rows of letters that were flashed very briefly (less than a second)
  - asked participants to report what letters they could remember
- discovered that ppl could still see the letters for a few seconds
- same is true for other sensory experiences
- relies on transient activity in sensory pathways
- if the sensory activity is not moved further, it decays
  - iconic memory — vision
  - echoic memory — hearing
  - haptic memory — somatosensory (touch)
Short term memory
- few minutes
- “working” memory
- used when needed and then discarded (2 factor authentication)
- this type of info stored determines what brain region is involved
  - language centers, vision, or somatosensory centers
Long term memory
- decades
- splits into explicit and implicit
- Recall = reconstruction
- takes time bc time is required to sort out which memories have highest emotional significance
- memories are flexible before they are consolidated
- even long-term memories can be disrupted during recall
- recall is an active process — RECONSTRUCTION

Patient H.M.

Henry Molaison (1926-2008)
seizures, surgery, anterograde amnesia
at age of 9, knocked down by bike and had head injury
due to injury, developed seizures and epilepsy
- seizure — sudden surge of electrical activity in brain that can cause wide range of symptoms which include convulsions, unusual sensations, and loss of consciousness
seizures worsened - by 27, had avg of 10 blackouts and one major seizure per week
hippocampus surgically removed
anterograde amnesia
researcher Dr. Brenda Milner studied H.M.
HM would read the same magazine repeatedly bc it was always new to him
could not remember ppl he had met after his surgery
however, when presented same puzzle several days in a row (although he did not remember having seen the puzzle before), speed at solving became faster each day

Brenda Milner’s discoveries

ability to acquire new memories must be a distinct cerebral function — not connected to any other perceptual or cognitive abilities bc they were not affected
HM could hold a new memory for a few minutes (to do a puzzle) → medial temporal lobe must not bc involved immediate memory bc it was intact → there are different types of memory and involve different brain regions
medial temporal lobes and hippocampus must not be required for the storage of old memories bc he could remember those
HM could only learn a particular type of new knowledge — carrying out tasks or learning skills such as tracing the outline of a star in a mirror even though he could not remember doing it in the past, he was able to repeat the task
learning of tasks and skills must be a diff process from remembering new information → explicit and implicit memories

Explicit (Declarative) Memory

semantic and episodic
memories of facts and events we can consciously remember, recall and declare; part of our consciousness
includes 2 types
- episodic — info abt events we have personally experienced; the what, where, and when of an event; also called autobiographical memory; ex: remembering 5th birthday
- semantic — knowledge abt words, concepts, and language; ex: knowing who the president is

Implicit (Non-Declarative) Memory

procedural and emotional conditioning
memories that are not part of our consciousness; formed thru behavior
- procedural — stores info abt how to do things; skills and actions - how to ride a bike, tying shoelaces, driving
- non-declarative memory can also include behavior learned thru emotional conditioning
  - might have a fear of spiders, but not consciously remember why or what occurred to condition that fear
  - emotional — often have more vivid and longer-lasting memories than neutral experiences, includes both neg and pos associations; phobias

Hebb’s Rule

cells that fire together, wire together
when two neurons active at same time, synaptic connection is stronger = allows two neurons to fire together easier in the future

Glutamate: AMPA and NMDA Receptor Activation

the primary excitatory neurotransmitter in the mammalian brain
mediates around 70% of synaptic transmission in the CNS
synthesized from glutamine, readily available in proteins
all cells can synthesize glutamate
it is important for longer-term processes and changes in the neuronal function
critical in learning and memory
- AMPA receptor
  - often coexist on the same neuron; fast; action; sodium flows in = excitatory
- NMDA receptor
  - both glycine and glutamate must be present
  - glycine is usually readily available in the synaptic cleft
  - slow action — the NMDA receptor is blocked by magnesium and its opening depends on membrane voltage
  - after glutamine binds to a nearby AMPA receptor