Bio Psychology

Foundations of Biological Psychology

Historical Overview

• The foundation of biological psychology is rooted in historical discoveries and understandings of the brain and its functions.

• A timeline of discoveries is utilized to orient the study of biological psychology.

Early Civilizations and the Brain

• Egyptian Papyrus (~1700 BCE):

  • The Edwin Smith papyrus is notable for being one of the first recorded uses of the brain.

  • The importance of understanding early contributions to modern biological psychology is emphasized.

  • Egyptian hieroglyphs reflect early knowledge regarding the brain, including recognition of head trauma effects.

• Recognition of the Cortex:

  • Ancient neuroscientists understood the existence of the cortex (the outer covering of the brain).

  • Awareness of conditions such as seizures and language impairments (aphasias) was present.

  • Knowledge regarding the laterality of movement was established, meaning movement is controlled by the opposite side of the brain.

Philosophical Developments

• Hippocrates:

  • Considered the brain as the center of thoughts and emotions.

  • There was contention regarding whether the heart was the true seat of consciousness.

  • The debate on the brain's role persisted, with recognition that emotional experiences could be detected through heart rate.

• Dualism:

  • The question of whether the brain and body are connected or separate arose, introducing the concept of dualism.

  • Rene Descartes:

  • Identified as the father of dualism, proposing that the mind and body are distinct entities.

  • Coined the term "reflex" and described the mind-body interaction as resembling two interactive machines.

  • Influenced by automatons, Descartes believed the mind (or soul) interacted with the body at the pineal gland, thought to be the seat of the soul.

Contributions to Biological Psychology

• Interaction of Mind and Body:

  • Descartes theorized that actions arose when the soul influenced the pineal gland, subsequently pressuring muscles.

  • Modern science has evolved to understand that consciousness is a product of physiological biological processes, indicating that the mind and body are intertwined rather than completely separate.

Key Discoveries

• Luigi Galvani:

  • Demonstrated that electrical stimulation could cause muscle contraction, advancing the understanding of nerve function.

  • Johannes Muller:

  • Proposed the concept of specific nerve energies, suggesting that different nerves have distinct functions corresponding to different brain regions.

  • Santiago Ramon y Cajal:

  • Utilized brain staining techniques to depict individual neurons, winning a Nobel Prize for his work.

  • Pioneered the understanding of the nervous system being composed of individual cells (neurons), similar to other body systems.

  • His detailed drawings mirrored what modern microscopy has confirmed about neural networks.

Anatomical Directions:

Neuraxis or CNS: Line drawn through the center of the brain and spinal cord, representing the axis of the nervous system.

PNS: Nerves that branch off CNS

Dorsal: Referring to the top or upper side of an organism (back of us humans) (Supieror)

Ventral: Referring to the beneath or lower side of an organism (Infeiror)

Caudal: Referring to the back or posterior part of an organism (Below of us humans) (Posterior)

Rostral: Referring to the front or anterior part of an organism (Anterior)

Ipsilateral: Referring to structures on the same side of the body (e.g., the right arm and right leg).

Contralateral: Referring to structures on opposite sides of the body (e.g., the right arm and the left leg).

Medial: Middle

Lateral: Referring to structures located towards the sides of the body

Anatomical Cuts:

Sagittal (Perpendicular to the ground)

Horizontal/Transverse (parallel to the ground)

Coronal (Like a deli)

What Is Neuroanatomy

• Neuroanatomy = structure of the nervous system, especially the brain

• This unit focuses on macro-level anatomy (whole brain structures)

• Function at the cellular level comes later

• Lab focuses on identifying structures on a sheep brain

How We Study the Brain

Lesion Studies

• Lesion = damage or removal of a brain region to observe lost function

• Helps establish structure–function relationships

Phineas Gage

• Damage to frontal lobe

• Result: poor impulse control, emotional dysregulation, personality change

• Shows frontal lobe role in inhibition and executive control

Henry Molaison (H.M.)

• Bilateral medial temporal lobectomy

• Hippocampi removed

• Could not form new declarative memories

• Cerebellum was intact so was able to form new procedural memories

• Old memories and procedural learning intact

• Shows hippocampus is required for memory formation, not storage

Brain Recording & Imaging

• EEG: excellent temporal resolution (when activity happens), poor spatial

• MRI / fMRI: excellent spatial resolution (where activity happens), tracks blood flow

• PET: shows neurotransmitter/metabolic activity

Phrenology (Historical Context)

• Pseudoscience claiming skull bumps reflect traits

• Used to justify racism and slavery

• Incorrect, but introduced idea of regional specificity

• Modern neuroscience keeps the idea, not the method

Overview of the Nervous System

Central Nervous System (CNS)

• Brain

• Spinal cord

Peripheral Nervous System (PNS)

• Nerves

• Ganglia

(Class focuses mainly on CNS)

Ventricular System

Ventricles (in order of flow)

1. Lateral ventricles (I & II) – supply cerebrum

2. Third ventricle – supplies diencephalon

3. Cerebral aqueduct – connects 3rd → 4th ventricle

4. Fourth ventricle – supplies hindbrain and spinal cord

• Ventricles contain cerebrospinal fluid (CSF)

Cerebrospinal Fluid (CSF)

What CSF Is

• Clear fluid in ventricles and subarachnoid space

Functions

• Cushions the brain (shock absorption)

• Allows brain to float in skull

• Removes toxins (glymphatic system, especially during sleep)

• Maintains stable neural environment

Production

• Produced by choroid plexus in all ventricles

• Constantly produced and reabsorbed

Clinical Relevance: Hydrocephalus

• Excess CSF buildup

• Causes brain compression and atrophy

• Can result from blocked cerebral aqueduct or poor reabsorption

• Treated by draining CSF or correcting cause

Cerebral Cortex

General Features

• Outer layer of brain (“bark”)

• Composed of gray matter (cell bodies)

• Inside is white matter (myelinated axons)

Gyri and Sulci

• Gyri = ridges

• Sulci = grooves

• Fissures = deep sulci

• Purpose: increase surface area → more neurons

Gray vs White Matter

• Gray matter: processing, develops earlier, declines with age

• White matter: connections, develops into adulthood, increases efficiency

Major Brain Divisions (Evolutionary Order)

Forebrain

• Telencephalon: cortex, basal ganglia, limbic system. Most recently evolved

• Diencephalon: thalamus, hypothalamus

Midbrain

• Mesencephalon

Hindbrain

• Metencephalon: cerebellum, pons

• Myelencephalon: medulla

Most recently evolved region:

• Prefrontal cortex (part of telencephalon)

Four Lobes of the Cerebral Cortex

Frontal Lobe

• Motor cortex (precentral gyrus)

• Speech production

• Planning and decision-making

• Impulse control

• Executive function

Damage → poor inhibition, personality changes

Parietal Lobe

• Somatosensory cortex (postcentral gyrus)

• Touch, pain, temperature

• Proprioception

• Spatial awareness

Occipital Lobe

• Primary visual cortex

• Processes and integrates visual information

Damage → cortical blindness even with intact eyes

Temporal Lobe

• Auditory cortex

• Language comprehension

• Sound processing and meaning

Listening to music primarily uses the temporal lobe

Limbic System (Subcortical)

Hippocampus

• Greek for “seahorse”

• Learning and memory formation

• Acts as a memory gateway, not storage

• Essential for consolidation

• Sleep is critical for hippocampal function

Damage → inability to form new memories (H.M.)

Amygdala

• Greek for “almond”

• Fear and anxiety

• Strengthens emotional memories

• Site of action for benzodiazepines (e.g., Xanax)

Fear = immediate threat
Anxiety = fear outside of immediate context

Diencephalon

Thalamus (“inner chamber”)

• Central relay station

• Gateway for all sensory systems except olfaction

• Sensory info passes through before reaching cortex

Key nuclei:

• Lateral geniculate nucleus (LGN) → vision

• Medial geniculate nucleus (MGN) → hearing

Important exam point:

• Smell bypasses the thalamus

Hypothalamus (“under thalamus”)

• Master controller of the endocrine system

• Controls pituitary gland

• Regulates the 4 F’s: fight, flight, feeding, mating

• Produces hormones like oxytocin, vasopressin

• Regulates growth and sex hormones

Suprachiasmatic nucleus (SCN)

• Controls circadian rhythm and sleep–wake cycle

• Receives light information directly from retina

Midbrain (Mesencephalon)

Tectum (“roof”)

• Superior colliculus: eye movements

• Inferior colliculus: sound localization

Tegmentum

• Substantia nigra

  • Dopamine + motor control

  • Degeneration → Parkinson’s disease

• Ventral tegmental area (VTA)

  • Dopamine + reward

  • Projects to nucleus accumbens

  • Core pathway in addiction, motivation, depression

Hindbrain

Cerebellum (“little brain”)

• Balance and coordination

• Procedural/muscle memory

• Automatic motor skills

• Involved in fine-tuning movement

Pons

• Means “bridge”

• Contains reticular activating system

• Involved in arousal and wakefulness

Locus coeruleus

• Regulates alertness and stress

• Too active → anxiety, poor focus

• Optimal activity → peak performance

Medulla Oblongata

• Controls vital functions:

  • Breathing

  • Heart rate

  • Blood pressure

  • Skeletal muscle tone

Damage → incompatible with life

Spinal Cord

Structure

• Gray matter inside, white matter outside (opposite of brain)

Function

• Dorsal horn: sensory input enters

• Ventral horn: motor output exits

• Capable of reflexes without brain involvement

Example: withdrawing hand from a hot surface before conscious awareness

High-Yield Review Facts

• Smell is the only sense that bypasses the thalamus

• Hippocampus = memory formation, not storage

• Amygdala = fear and anxiety

• Prefrontal cortex = most recently evolved

• Cerebellum = automatic movement and procedural memory

• Medulla = life-sustaining functions

Meninges:

Major source of protection for CNS

1. Dura mater (Durability)

2. Subdural Space

3. Acrachnoid membrane (Weblike)

4. Subarchnoid Space

5. Pia Matter (delicate)

Neurophysiology:

A nueron is one of the many cells in a brain

Two types of main cells:

Neurons: Synaptic Transmission. The process by which signals are transmitted from one neuron to another across a synapse.

Glial Cells: Support and protect neurons by providing structural support, nutrition, and insulation, and by assisting in signal transmission.
Neurons of the central nervous system are provided nutrients, oxygen, and physical support by glial or neuroglial cells.

All connected to the Soma: the cell body of a neuron that contains the nucleus, DNA, mitochondria, and ribosomes and keeps it alive.

Dentrites: Finger-like projections of a neuron that receive signals from other neurons and transmit them towards the soma, playing a crucial role in how information is processed within the nervous system.

Axon: A long, thin projection of a neuron that has an action potential that transmits electrical impulses away from the soma to other neurons, muscles, or glands, facilitating communication throughout the nervous system.

The axon connects to the dendrites with a synapse.

Excited vs inhibit: Excited signals (like putting your hand on a hot pot) increase the likelihood that a neuron will fire an action potential, while inhibitory signals decrease that likelihood.

Neuronal Function & Synaptic Communication

1. Cells of the Nervous System

The nervous system contains billions of cells. Only about 10% are neurons, while the remaining 90% are supporting cells known as glia.

Three Types of Neurons

1. Sensory Neurons: Carry information from the peripheral nervous system (PNS) to the central nervous system (CNS).

2. Interneurons: Located entirely within the CNS. They relay information between sensory and motor neurons.

3. Motor Neurons: Carry instructions from the CNS to the muscles to produce movement.

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2. Anatomy of a Neuron

Neurons function like a complex electrical circuit. They are often compared to trees to help visualize their structure.

• Soma (Cell Body): The heart of the neuron. It contains the nucleus and DNA. It provides the life processes of the cell through machinery like mitochondria (energy) and ribosomes (protein).

• Dendrites: Branch-like structures that act as antennae. They receive messages from other neurons across the synapse. Dendritic branching (arborization) can grow or shrink based on learning or mental health conditions.

• Axon: A long, slender tube that transmits electrical messages (action potentials) from the soma to the terminal buttons.

• Myelin Sheath: A fatty insulation (lipids) that covers the axon. It speeds up the electrical signal and prevents it from leaking out.

• Nodes of Ranvier: Gaps in the myelin sheath. The action potential regenerates at these points, a process called saltatory conduction.

• Terminal Buttons: Located at the end of the axon branches. They secrete chemicals called neurotransmitters into the synapse.

3. Supporting Cells: Glia

Glia (meaning "glue") provide a scaffold for neurons and perform vital maintenance.

4. Resting Membrane Potential

The resting membrane potential is the electrical charge of a neuron when it is not active. The inside of the cell is typically -70 mV relative to the outside.

Key Ions

• Sodium ($Na^+$): Highly concentrated outside the cell. It is positively charged.

• Potassium ($K^+$): Highly concentrated inside the cell. It is positively charged. Potassium (K+) is the ion that predominantly in the intracellular fluid at rest.

• Chloride ($Cl^-$): High concentration outside the cell. Negatively charged.

• Organic Anions ($A^-$): Found only inside the cell. Negatively charged.

Physical Forces

1. Diffusion: The tendency of molecules to move from areas of high concentration to low concentration.

2. Electrostatic Pressure: The force that attracts opposite charges (+ and -) and repels like charges.
   Both of these mediate resting membrane potential.

3. Sodium-Potassium Pump: A protein that maintains the balance by pumping 3 sodium ions out and 2 potassium ions in.

5. The Action Potential

The action potential is an all-or-none electrical impulse. Once the cell reaches the threshold of excitation (roughly -65 to -60 mV), the process triggers automatically.

Steps of the Action Potential

1. Depolarization: Voltage-gated sodium channels open. Sodium ($Na^+$) rushes into the cell, making the inside positive (up to +40 mV).

2. Repolarization: Sodium channels close (refractory period). Potassium channels open and potassium ($K^+$) rushes out of the cell, making the inside negative again.

3. Hyperpolarization: The cell briefly becomes more negative than its resting state before the sodium-potassium pump restores the -70 mV balance.

6. Synaptic Transmission

Communication between neurons is an electrochemical event. An electrical signal (action potential) triggers the release of a chemical signal (neurotransmitter).

• Synapse: The microscopic gap between the terminal button of the presynaptic neuron and the dendrite of the postsynaptic neuron.

• Vesicles: Small orbs in the terminal button that store neurotransmitters.

• Calcium ($Ca^{2+}$): When an action potential reaches the terminal, calcium enters the cell, causing vesicles to fuse with the membrane and release their contents.

Receptor Types

• Ionotropic Receptors: Fast-acting. The neurotransmitter binds directly to a channel, causing it to open immediately.

• Metabotropic Receptors: Slower. The neurotransmitter binds to a receptor that activates a G-protein, which then triggers a series of internal chemical steps to open a channel.

7. Postsynaptic Potentials (PSPs)

When a neurotransmitter binds to a receptor, it changes the charge of the receiving cell.

• Excitatory PSP (EPSP): Makes the cell more positive (depolarization), increasing the chance it will fire. Usually involves sodium or calcium entering the cell.

• Inhibitory PSP (IPSP): Makes the cell more negative (hyperpolarization), decreasing the chance it will fire. Usually involves potassium leaving or chloride entering the cell.

Neural Integration (Summation)

A single neuron may receive hundreds of messages at once. The cell body adds up the total number of EPSPs and IPSPs. If the net charge reaches the threshold of excitation, the neuron fires. If the inhibitory messages outweigh the excitatory ones, the neuron remains silent.

8. Termination of the Signal

To prevent a signal from continuing indefinitely, neurotransmitters must be removed from the synapse.

1. Reuptake: The presynaptic neuron uses transporters to pull the neurotransmitter back inside to be recycled.

2. Enzymatic Deactivation: Specific enzymes (like "Pac-Man") break the neurotransmitter apart so it can no longer bind to receptors.

Foundations of Behavioral Neuroscience

The goal of behavioral neuroscience is to explain behavior through two levels of explanation: generalization (deducing general laws from specific events) and reduction (explaining phenomena via basic elements).

The Mind-Body Question

• Dualism: The belief that the mind and body are separate entities.

  
  

• Monism: The belief that the mind is a product of the body; they are one. This is the modern scientific perspective.

  
  

• René Descartes: A dualist who was the first to suggest a link between the mind and the brain. He believed the soul interacted with the body in the pineal body.

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Historical Milestones

• Luigi Galvani: Used electrical stimulation on frog nerves to prove that muscle contraction did not require the brain, shifting the focus to the electrical nature of nerve messages.

  
  

  
  

• Johannes Müller: Developed the Doctrine of Specific Nerve Energies, stating that while all nerves carry the same electrical signal, the perception depends on which part of the brain receives the signal.

  
  

  
  

• Ramon Santiago y Cajal: Used Golgi staining to prove the nervous system is made of individual neurons rather than a continuous network.

  
  

  
  

Cellular Structure and Function

The Neuron

Neurons are the primary cells of the brain. They consist of:

• Soma (Cell Body): Contains the nucleus and internal organelles.

  
  

• Dendrites: Receive signals from other neurons.

  
  

• Axon: Carries the action potential from the soma to the terminal buttons.

  
  

  
  

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  Terminal Buttons: Sites where neurotransmitters (NTs) are released into the synapse.

  
  

Internal Components

• Mitochondria: Extract energy from nutrients to produce ATP.

  
  

  
  

• Microtubules: Form the cytoskeleton and facilitate axoplasmic transport.

  
  

  
  

  • Anterograde: Movement from soma to buttons via the protein kinesin.

    
    

  • Retrograde: Movement from buttons back to soma via dynein.

    
    

• Blood-Brain Barrier (BBB): A selectively permeable barrier that protects the CNS by controlling the composition of substances in the brain.

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Supporting Cells (Glia)

Glia provide physical and functional support to neurons.

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  Astrocytes: Provide nourishment by converting glucose to lactate and help isolate synapses.

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  Oligodendrocytes: Produce the myelin sheath in the CNS.

  
  

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  Schwann Cells: Produce myelin in the PNS and help with nerve regeneration after injury.

  
  

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  Microglia: Act as part of the immune system by removing debris via phagocytosis.

  
  

Electrical Potentials and Communication

Resting and Action Potentials

The resting potential of a neuron is $-70\text{mV}$. This charge is maintained by the sodium-potassium pump, which pushes three $Na^{+}$ ions out for every two $K^{+}$ ions it brings in.

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The Action Potential Sequence:

1. The cell reaches the threshold of excitation.

   
   

2. Voltage-dependent $Na^{+}$ channels open; $Na^{+}$ rushes in, causing depolarization up to $+40\text{mV}$.

   
   

3. $K^{+}$ channels open; $K^{+}$ rushes out.

   
   

4. 
   

   $Na^{+}$ channels close and become refractory.

   
   

5. 
   

   $K^{+}$ continues to leave, causing the membrane to return toward its resting state and briefly hyperpolarize (overshoot).

   
   

Neuroanatomy

The Ventricular System and CSF

The brain floats in Cerebrospinal Fluid (CSF), which is produced by the choroid plexus. It circulates through the lateral ventricles, third ventricle, cerebral aqueduct, and fourth ventricle.

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Major Brain Regions

Psychopharmacology

Pharmacokinetics (ADME)

Pharmacokinetics is the study of what the body does to a drug.

Absorption: Routes of administration determine speed. Intravenous (IV) is the fastest human route. Inhalation is also very quick as it goes from lungs to heart to brain.

• Distribution: Lipid solubility is the most important factor in how fast a drug reaches the brain. Heroin reaches the brain faster than morphine because it is more lipid soluble, resulting in a "rush".

  
  

• Metabolism: Primarily occurs in the liver via enzymes.

  
  

• Excretion: Primarily occurs via the kidneys into urine.

  
  

  
  

Repeated Exposure

• Tolerance: A decrease in drug effect after repeated use.

  
  

• Sensitization: An increase in drug effect after repeated use.

  
  

• Withdrawal: Compensatory symptoms that appear when drug use stops; signifies physical dependence.

  
  

  
  

Margin of Safety

The Therapeutic Index (TI) measures a drug's safety by comparing the toxic dose ($TD_{50}$) to the effective dose ($ED_{50}$).

• Barbiturates: Have a low TI (2–3), making them dangerous.

• Benzodiazepines: Have a high TI (100+), making them much safer for treating anxiety.

Neurotransmitter Systems

More notes:
I. History and Evolution

• Ancient Perspectives: While you noted Hippocrates, remember that Aristotle and other Greeks believed behavior was centered in the heart. Galen contributed by dissecting and studying non-human animal brains to understand behavior.

  
  

  
  

• Functionalism: This principle states that an organism’s characteristics perform useful functions rather than having a predetermined "purpose". For example, the forelimbs of different species are adapted for specific functional needs.

  
  

  
  

• Natural Selection: This is the mechanism where heritable variations that lead to greater reproductive success become more prevalent in a population over time.

  
  

  
  

• Human Evolution: Homo erectus left Africa 1.7 million years ago. Homo neanderthalis lived in Western Europe between 120,000 and 30,000 years ago. Homo sapiens evolved in East Africa 100,000 years ago.

  
  

• Why Large Brains? Human competition required large brains for tool use, color vision to spot food/danger, fire for cooking/heat, upright posture for long-distance travel, and language for group communication.

  
  

II. Internal Cell Structure and Transport

• Organelles: The nucleolus is responsible for producing ribosomes, which synthesize proteins. Smooth Endoplasmic Reticulum produces lipid molecules. Lysosomes are sacs containing enzymes that break down waste products.

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• Axoplasmic Transport: This process moves substances along microtubules within the axon.

  
  

  
  

  • Anterograde: Movement from the soma toward the terminal buttons using the protein kinesin.

    
    

  • Retrograde: Movement from the terminal buttons back to the soma using the protein dynein. It is approximately half as fast as anterograde transport.

    
    

    
    

III. The Synapse: Vesicles and Binding

• Vesicle Release: When a vesicle releases neurotransmitters, it forms an omega structure. After release, the "Kiss and run" method allows the pore to close and the vesicle to refill without fully integrating into the membrane. Alternatively, the "Merge and recycle" method integrates the vesicle into the membrane.

  
  

  
  

• Vesicle Pools:

  • Release-ready: Docked against the membrane; accounts for less than 1% of vesicles.

    
    

  • Recycling pool: Makes up 10 to 15%.

    
    

  • Reserve pool: Makes up 85 to 90% and only opens during high rates of axon firing.

    
    

• Binding Types:

  • Competitive binding: Direct agonists or antagonists act directly on the neurotransmitter binding site.

    
    

  • Non-competitive binding: Indirect agonists or antagonists act on an alternative site to modify the effect of the neurotransmitter on the ion channel.

    
    

IV. Specific Neuroanatomy

• Basal Ganglia: This system controls movement and consists of the caudate, putamen, and globus pallidus.

  
  

• Thalamic Nuclei:

  • Lateral geniculate nucleus (LGN): Relays visual information.

    
    

    
    

  • Medial geniculate nucleus (MGN): Relays auditory information.

    
    

  • Ventrolateral nucleus: Relays information from the cerebellum to the primary motor cortex.

    
    

• Autonomic Systems: The Sympathetic division is also known as the thoracolumbar system. The Parasympathetic division is known as the craniosacral system.

  
  

  
  

• Vagus Nerve: The 10th cranial nerve that regulates the organs in the thoracic and abdominal cavities.

  
  

V. Pharmacology and Histamine

• Injections: In lab animals, Intraperitoneal (IP) injection is the second fastest route of administration.

  
  

• Histamine: This neurotransmitter is vital for wakefulness and arousal. It is synthesized from histidine and acts on H1 through H4 receptors.

  
  

  Drugs that block histamine receptors produce drowsiness

Week 7:

Stages of Sleep and EEG Patterns

Sleep is categorized into distinct stages characterized by specific electrical activity in the brain.

Waking and NREM Sleep

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  Waking State: Characterized by alpha activity ($8-12\text{ Hz}$) and beta activity ($13-30\text{ Hz}$).

  
  

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  Stage 1 (NREM): Consists of theta activity ($3.5-7.5\text{ Hz}$).

  
  

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  Stage 2 (NREM): Contains sleep spindles ($12-14\text{ Hz}$ occurring $2-5$ times during stages $1-3$) and K complexes, which are sudden, short waveforms.

  
  

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  Stage 3 (Slow-Wave Sleep): Defined by delta activity, which is characterized by frequencies <3.5\text{ Hz}.

  
  

REM Sleep

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  REM Characteristics: REM sleep consists of theta and beta activity.

  
  

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  Prefrontal Cortex: Shows low activity during REM, reflecting the lack of organization and planning found in dreams.

  
  

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  Extrastriate Cortex: Shows high activity during REM, reflecting visual hallucinations during dreaming.

  
  

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  Striate Cortex: Shows low activity during REM due to a lack of visual input.

  
  

Functions of Sleep and Learning

Sleep serves critical roles in physical recovery and memory consolidation.

Recovery and Development

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  Slow-Wave Sleep (SWS): Allows the brain to recover from physical activities of the day, though not necessarily cognitive activity.

  
  

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  Synaptic Erasure: Sleep assists in targeted synaptic erasure, which is essential for memory consolidation.

  
  

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  REM Sleep: Promotes brain development.

  
  

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  Age Differences: Young humans spend more time in REM ($9-10$ hours) compared to those with more developed brains (8 hours).

  
  

Memory Consolidation

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  Nondeclarative Memory: Consolidated primarily during REM sleep.

  
  

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  Declarative Memory: Consolidated primarily during slow-wave sleep.

  
  

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  Learning Tasks: Naps containing both SWS and REM show significantly higher discrimination improvement compared to no naps or SWS-only naps.

  
  

Neurotransmitters of Arousal and Sleep

Specific chemical systems modulate the transitions between waking and sleep states.

Sleep/Wake Transitions: Flip-Flop Circuits

Transitions between states are managed by mutual inhibition between sleep-promoting and arousal-promoting regions.

• Ventrolateral Preoptic Area (vlPOA): The primary sleep-promoting region containing the majority of sleep neurons.

  
  

• Inhibitory Mechanism: These neurons secrete GABA and send axons to arousal regions.

  
  

• Mutual Inhibition: The sleep neurons in the vlPOA receive inhibitory inputs from the locus coeruleus (LC), raphe nuclei (DR), and tuberomammillary nucleus (TN).

  
  

• Flip-Flop "Off": When the vlPOA is activated, the brain enters slow-wave sleep.

  
  

• Flip-Flop "On": When arousal systems are activated, they inhibit the vlPOA, resulting in an alert waking state.

  
  

Biological Clocks and Circadian Rhythms

Daily rhythmic changes in behavior and physiology are controlled by internal biological clocks.

• Circadian Rhythm: Daily changes in physiological processes.

  
  

  Zeitgeber: A stimulus, most commonly light, that resets the biological clock.

  
  

  Suprachiasmatic Nucleus (SCN): Located in the hypothalamus, this region contains the biological clock for many circadian rhythms.

  
  

  Melanopsin: A photopigment in retinal ganglion cells that provides light information to the SCN.

  
  

  Pineal Gland: Secretes melatonin to control seasonal rhythms and rhythms influenced by day length.

  
  

  Rhythm Disruption: Lesions to the SCN, paraventricular nucleus (PVN), or pineal gland disrupt rhythms controlled by day length.

Week 8:

Gemini said

These notes cover the core concepts of brain development from the PSYC 324 lecture, focusing on prenatal stages, anatomical structures, and the neurological shifts during adolescence.

Course Logistics

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  Instructor: Shawn Bates, PhD, Chico State.

  
  

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  Deadlines: Discussion board is due Wednesday; check-up is scheduled for Friday.

  
  

Early Brain & Prenatal Development

Brain development begins early in embryonic life as a hollow tube. This tube maintains its basic shape even as it matures, though it elongates, folds, and thickens to reach its final form.

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The Neural Tube (Days 20–24)

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  Day 20: The neural plate of the forebrain begins to form a neural groove and neural folds.

  
  

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  Day 21: The neural folds begin to fuse.

  
  

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  Day 24: The fused tube gives rise to the brain and spinal cord. The central canal of the spinal cord remains as the interior space.

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Early Sensory & Emotional States

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  Synesthesia: Infants experience a blending of senses.

  
  

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  Memory: Declarative memories (facts/events) do not form until approximately age 3.

  
  

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  Myelination: This process makes babies aware of the world. It happens in different regions at different times.

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  Trauma: Early traumatic experiences can have long-lasting developmental effects.

  
  

Anatomical Subdivisions

The brain is categorized by major divisions, their associated ventricles, and the resulting principal structures.

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Adolescent Brain Alterations

Adolescence is marked by significant reorganization at the cellular and behavioral levels.

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Neuronal Changes

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  Overproduction & Pruning: The brain overproduces neurons, followed by competitive pruning and apoptosis (programmed cell death).

  
  

• 
  

  Optimization: Myelination increases drastically, creating more efficient neural circuits.

  
  

• 
  

  Prefrontal Cortex (PFC): This is the last region to fully develop. A longer period of PFC alteration is associated with higher adult IQ.

  +1

  
  

Reward & Emotion

• 
  

  Dopamine Signaling: Circuit density and dopamine signaling increase.

  
  

• 
  

  Reward Sensitivity: Strong rewards feel intense, while small rewards can feel aversive.

  
  

• 
  

  Regulation: Because the PFC is immature, the ventral striatum takes the lead in regulating emotions.

  
  

• 
  

  Reactivity: Adolescents are more reactive to emotional faces and regulate the amygdala differently than adults.

  
  

• 
  

  Mental Health: Most mental illnesses have their onset during adolescence.

  
  

Behavioral Patterns

• 
  

  Novelty Seeking: This behavior is common in primates and may be necessary for developing adult behaviors.

  
  

Risk Taking: High activation in reward areas leads to increased risk-taking and a higher likelihood of developing substance abuse issues.

These notes cover the biological foundations of sensation and perception, specifically focusing on the visual and auditory systems.

Fundamentals of Sensation and Perception

Perception is the process of the brain interpreting neural signals to represent the external world.

• 
  

  Action Potentials: The brain only receives input in the form of action potentials traveling along sensory pathways.

  
  

• 
  

  Transduction: This is the process where sensory receptors convert physical energy, like light or sound waves, into nerve impulses.

  
  

• 
  

  Sensory Encoding: The brain understands how energy turns into impulses and the pathways those impulses take, but it is less clear how these signals become a full representation of the world.

  
  

• 
  

  Perceptual Illusions: These demonstrate the gap between sensory input and our brain's interpretation.

  
  

The Visual System

The Stimulus and Anatomy of the Eye

Visual perception begins with light, which is the specific part of the electromagnetic spectrum humans can detect.

• 
  

  Retina: This is the back of the eye where transduction occurs.

  
  

• Photoreceptors:

  • 
    

    Rods: Approximately 120 million cells that are sensitive to low-intensity light, making them essential for night vision.

    
    

  • 
    

    Cones: Approximately 6 million cells responsible for color vision and fine detail in bright light.

    
    

• 
  

  Fovea: The central region of the retina where cones are most dense and vision is sharpest.

  
  

• 
  

  Optic Disk: The location where ganglion cell axons exit the eye to form the optic nerve; it creates a blind spot because it lacks photoreceptors.

  
  

Visual Transduction and Retinal Circuitry

Transduction happens when light hits photopigments, such as rhodopsin, in the photoreceptors.

• 
  

  Hyperpolarization: Light causes the photoreceptor membrane to hyperpolarize.

  
  

• 
  

  Darkness: In the dark, photoreceptors actually depolarize bipolar cells.

  
  

• 
  

  Cell Layers: Information flows from photoreceptors to bipolar cells, and then to ganglion cells.

  
  

• 
  

  Horizontal and Amacrine Cells: These cells facilitate communication across the retinal layers.

  
  

Neural Pathways and the Brain

Information from the left visual field is processed in the right hemisphere, and information from the right visual field is processed in the left hemisphere.

1. 
   

   Optic Nerve: Formed by ganglion cell axons.

   
   

2. 
   

   Lateral Geniculate Nucleus (LGN): A part of the thalamus with six layers.

   
   

3. 
   

   Striate Cortex (V1): The primary visual cortex in the occipital lobe where visual information is first combined.

   
   

LGN Layer Properties

The LGN segregates different types of visual information.

Higher-Order Visual Processing

Beyond V1, the brain uses two distinct "streams" for processing.

• Dorsal Stream (The "Where" Pathway):

  • Projects from V1 to the parietal lobe.

    
    

  • Processes spatial awareness and guides actions.

    
    

  • Receives primary input from the magnocellular system.

    
    

• Ventral Stream (The "What" Pathway):

  • Projects from V1 to the inferior temporal lobe.

    
    

  • Processes object recognition and color.

    
    

  • Receives primary input from the parvocellular system.

    
    

Visual Pathologies (Agnosias)

Damage to the ventral stream can lead to agnosia, or "not knowing".

• 
  

  Visual Agnosia: Inability to recognize objects.

  
  

• 
  

  Achromatopsia: Inability to recognize colors.

  
  

• 
  

  Prosopagnosia: Inability to recognize faces.

  
  

The Auditory System

The Auditory Stimulus

Sound is produced by vibrating objects that cause air molecules to move in waves.

Anatomy of the Ear

1. 
   

   Outer Ear: The pinna directs sound waves into the ear canal.

   
   

2. Middle Ear:

   • 
     

     Tympanic Membrane: The eardrum vibrates in response to sound.

     
     

   • 
     

     Ossicles: Three tiny bones (malleus, incus, and stapes) that transmit vibrations to the inner ear.

     
     

3. 
   

   Inner Ear (Cochlea): A snail-shaped structure containing the mechanisms for transduction.

   
   

   • 
     

     Oval Window: Receives vibrations from the stapes to move fluid inside the cochlea.

     
     

   • 
     

     Organ of Corti: The sensory organ on the basilar membrane.

     
     

Auditory Transduction

• 
  

  Hair Cells: These are the receptive cells of the auditory system.

  
  

• 
  

  Cilia and Tip Links: Movement of the basilar membrane causes the cilia (tiny hairs) to bend.

  
  

• 
  

  Ion Channels: When cilia bend toward the tallest one, tension on "tip links" opens ion channels (K+ and Ca2+), increasing the firing rate. Bending away closes the channels.

  
  

• 
  

  Neurotransmitter: Glutamate is the primary neurotransmitter used here.

  
  

Auditory Pathways and Perception

The auditory system is organized tonotopically, meaning different frequencies are processed in different locations.

• Cochlear Mapping:

  • 
    

    Basal End: Responds to high frequencies.

    
    

  • 
    

    Apical End: Responds to low frequencies.

    
    

• 
  

  Neural Pathway: Information travels from the cochlear nerve to the medulla (cochlear nucleus and superior olivary complex), then to the inferior colliculus, the medial geniculate nucleus (MGN) of the thalamus, and finally the auditory cortex.

  
  

• Auditory Cortex Streams:

  • 
    

    Anterior Stream: Analyzes complex sounds (the "what").

    
    

  • 
    

    Posterior Stream: Sound localization (the "where").

    
    

Coding of Pitch and Loudness

• 
  

  Place Coding: High and moderate frequencies are coded by which part of the basilar membrane is vibrating.

  
  

• 
  

  Rate Coding: Low frequencies are coded by the firing rate of neurons at the apical end.

  
  

• 
  

  Loudness Coding: Determined by the rate of action potentials and the shearing force on the cilia.

Week 10:

These notes cover the biological basis of emotion, aggression, and impulse control based on the PSYC 324 lecture material from Dr. Shawn Bates at Chico State.

I. Components of Emotional Response

An emotional response consists of three integrated components:

• 
  

  Behavioral: Muscular movements appropriate to the situation.

  
  

• 
  

  Autonomic: Physiological changes that facilitate the behavioral response.

  
  

• 
  

  Hormonal: Reinforcement of autonomic responses.

  
  

  • The adrenal medulla releases epinephrine and norepinephrine to increase blood flow to muscles.

    
    

• 
  

  The Amygdala: This structure controls the integration of these three components.

  
  

II. Fear and the Amygdala

The amygdala, located in the temporal lobes, is the primary region for processing fear and aversive stimuli.

Key Nuclei

• 
  

  Lateral Nucleus (LA): Receives information from all regions of the neocortex, thalamus, and hippocampal formation.

  
  

• 
  

  Central Nucleus (CeA): The region responsible for the expression of emotional responses.

  
  

  • 
    

    Damage to CeA: Abolishes fear responses; animals become tamer, have lower stress hormones, and show no fear toward natural predators.

    
    

  • 
    

    Activation of CeA: Heightens emotional reactivity; chronic activation can cause ulcers.

    
    

Conditioned Emotional Response

This is the most basic form of emotional learning, where a neutral stimulus is paired with an emotion-evoking one.

• 
  

  Neural Pathway: Information flows from the lateral nucleus to the central nucleus of the amygdala.

  
  

• 
  

  Social Learning: Humans and animals can also acquire fear by observing others (e.g., watching a dog attack someone else).

  
  

III. Aggression and Serotonin

Aggression involves threat behaviors (warning of attack), defensive behaviors, and submissive behaviors.

Neural Circuitry

• 
  

  Motor behaviors for aggression are organized in the brain stem, specifically the periaqueductal gray (PAG).

  
  

  • 
    

    Dorsal PAG (dPAG): Involved in defensive behaviors.

    
    

  • 
    

    Ventral PAG (vPAG): Involved in predation.

    
    

• The hypothalamus (HT) and amygdala (AMY) influence the PAG to control these behaviors.

  
  

Role of Serotonin (5-HT)

Serotonin acts as an inhibitor of aggression in both animals and humans.

• 
  

  Decreased Serotonin: Associated with antisocial behavior and increased aggression.

  
  

• 
  

  Serotonin Agonists: Drugs that increase 5-HT activity (like SSRIs) decrease irritability and aggressive tendencies.

  
  

IV. Impulse Control and the vmPFC

The ventromedial prefrontal cortex (vmPFC) acts as an interface between emotional responses and the control of complex behaviors.

• 
  

  Damage/Lesions: Lead to emotional instability, impaired decision-making, and poor "real-world competencies".

  
  

• 
  

  Phineas Gage: A famous case where vmPFC damage resulted in a complete change in personality and loss of impulse control.

  
  

• 
  

  Iowa Gambling Task (IGT): Patients with vmPFC damage fail this task because they lack the normal Galvanic Skin Response (SCR) that typically precedes a risky choice.

  
  

Brain Development

Impulse control improves as the brain matures.

• 
  

  Amygdala: Matures early.

  
  

• 
  

  PFC: Matures late (into adulthood), which explains why adolescents often struggle with impulse control and cognitive processing speed.

  
  

V. Communication and Recognition of Emotion

Facial Expression

• 
  

  Innate Responses: Facial expressions of emotion appear to be innate and universal, rather than learned. This is evidenced by similar expressions across different cultures and species.

  
  

• 
  

  Facial Feedback Hypothesis: The contraction of facial muscles can intensify the emotion being felt (e.g., smiling can make you feel happier).

  
  

Neural Basis of Recognition

• 
  

  Laterality: The right hemisphere is more important for recognizing and expressing emotion.

  
  

• 
  

  Amygdala: Crucial for recognizing facial expressions of fear.

  
  

• 
  

  Insular Cortex: Specifically activated during the perception of disgust, likely for disease avoidance.

  
  

• 
  

  Superior Temporal Sulcus (STS): Important for recognizing the direction of gaze of others.

  
  

Empathy and Mirror Neurons

• 
  

  Mirror Neuron System: Located in the ventral premotor area of the frontal lobe, these neurons fire both when we perform an action and when we see someone else perform it.

  
  

• 
  

  Social Transfer of Pain: Empathy involves the Anterior Cingulate Cortex (ACC).

  
  

  • Transfer of pain is dependent on ACC-Nucleus Accumbens (NAc) projections.

    
    

  • Transfer of fear is dependent on ACC-Basolateral Amygdala (BLA) projections.