Lecture 3- Biological Basis and Brain Mapping Methods

Biological and Psychological Connection

• Every psychological state has a biological basis.

Brain Mapping Methods: Phrenology

• Phrenology was an early method attempting to map the brain.
• It proposed that skull shape reflects brain size and cognitive functions.
• This method was discredited by the mid-1800s.
• Phrenology has a dark history,linked to eugenics, and the false belief that bumps on the skull could identify criminal tendencies.

Brain Mapping Methods: Brain Damage

• Studying cognitive function in people with brain damage, as part of neuropsychology, can help understand how the brain works.
• Neuropsychological tests assess cognitive function.
• Tests must be designed to accommodate language and cultural nuances.
• Animal studies with controlled brain lesions help in studying behavior.

Considerations for Brain Mapping Techniques

• Invasiveness, such as whether radiation is involved, must be considered.
• Accessibility of the technique is important.
• The focus can be on either the structure or the function of the brain.

Computerized Tomography (CT) Scan

• CT scans use X-rays to create images based on varying densities within the brain.
• CT scans can be used to show brain tumors.

Positron Emission Tomography (PET) Scan

• PET scans help to show brain activity.
• They involve injecting a mildly radioactive substance and monitoring blood flow changes in different brain areas.

Magnetic Resonance Imaging (MRI) & Functional MRI (FMRI)

• MRI uses magnetic fields to produce pictures of tissue.
• FMRI shows changes in metabolic activity over time.

Electroencephalography (EEG)

• EEG records electrical activity of the brain via electrodes on the scalp.
• EEG research can study the precise timing of overall brain activity by tracking amplitude and frequency.
• Studying small brain areas with EEG is challenging.

Magnetoencephalography (MEG)

• MEG measures tiny magnetic fields generated by the brain.
• MEG can be used to identify the location of epilepsy-related seizures.

Brain Stimulation Techniques

• Deep brain stimulation (DBS) modifies brain function through implanted electrodes
• DBS used as a treatment for disorders like Parkinson's and depression.
• Transcranial magnetic stimulation (TMS) applies strong, quickly changing magnetic fields to the skull's surface to enhance or interrupt brain function.

Brain Imaging Technique Questions

• Brain waves changing as a person falls asleep can be observed by brain-imaging techniques
• Structural abnormalities, like stroke damage, can be uncovered by brain-imaging techniques
• Brain structures can be examined without exposing a patient to radiation by using brain-imaging techniques

The Nervous System: An Overview

• Neurons are the building blocks and are consistently created and pruned during life.
• Action potentials are nerve impulses or electrical signals that travel down an axon.
• Glial cells support, nourish, and protect neurons.
• Neurons meet at synapses and communicate through neurotransmission.

Neurons: The Brain's Communicators

• Neurons are specialized nerve cells communicating with each other.
• They are building blocks of the nervous system, and transmit information in the form of electrical signals.

Neural Components

• Cell body (soma): the neuron's center, builds new cell components.
• Dendrites: branchlike extensions that receive information.
• Axons: "tails" that transmit information.
• Axon terminal: knob at the end of the axon with synaptic vesicles filled with neurotransmitters.
• Synapse: space between neurons through which neurotransmitters travel.

Glial Cells

• Glial means glue, are plentiful in the brain.
• They play a support role, contributing to psychological functioning by making myelin.
• They also feed and protect neurons.

Myelin Sheath

• Myelin sheath is fatty insulation from glial cells surrounding the axon.
• Multiple sclerosis(MS) involves the loss of myelin, causing erratic signals.

How a Neuron Fires Step 1: Resting Potential

• Neurons are polarized: negative inside, positive outside.
• They are selectively permeable, not allowing sodium ions (Na+) to pass through.

How a Neuron Fires Step 2: Action Potential

• Action potential: a brief electrical charge that travels down the neuron.
• Used to transmit neural messages to other neurons, muscles, etc.
• The neuron depolarized when stimulated (gates open, Na+ rushes in).
• All-or-none law applies to action potential
• Frequency of action potential = its intensity.

How a Neuron Fires Steps 3-5

• Repolarization (step 3): Potassium (Ka+) flows out, repolarizing the axon.
• Return to resting potential (step 4)
• Refractory period (step 5): A brief period where the neuron won't fire, despite stimulation.

Electrochemical Communication

• When an electrical signal reaches the end of an axon (electro), neurotransmitters released into the synapse (chemical)
• Neurotransmitters then bind to receptors of the receiving neuron's dendrites, transmitting the signal.
• Excitatory messages increase the likelihood a neuron will fire.
• Inhibitory messages decrease the likelihood that a neuron will fire.

Neurotransmitters

• Neurotransmitters are chemical messengers that help neurons communicate and influence emotions and mood, like serotonin and dopamine.
• They control movement, such as acetylcholine release, regulate sleep and alertness, such as GABA and norepinephrine, and influence learning, memory (glutamate)
• Neurotransmitters are implicated in mental illness.

Neurotransmission Processes

• Release: Action potential triggers neurotransmitter (NT) release from vesicles into the synaptic cleft.
• Reuptake: NTs bind to receptors on the postsynaptic neuron, acting as a lock and key
• Reuptake: Excess NT's are removed by drifting away, being broken down, or reabsorbed. NTs also are taken back into the presynaptic neuron (recycled). -Drugs like cocaine block reuptake, prolonging the effects of neurotransmitters.

Neurotransmitters: Helpers & Blockers

• Agonist: mimic or enhance the effect of a neurotransmitter
• Antagonist: block or impede the activity of a neurotransmitter
• Opioids (e.g., fentanyl) vs. Naloxone
• Schizophrenia is associated with excess dopamine, treated with dopamine antagonists.
• Parkinson's is linked to low dopamine, and is treated with dopamine agonists.

Key Neurotransmitters

• Glutamate
• GABA
• Acetylcholine
• Dopamine
• Serotonin
• Anandamides

Glutamate and GABA

• Glutamate and GABA are the most common neurotransmitters in the CNS.
• They are associated with learning and memory
• Glutamate is excitatory, increases the chance neurons communicate, but, is toxic in high doses, and can contribute to schizophrenia.
• GABA is inhibitory and dampens neural activity.

Acetylcholine

• Acetylcholine is involved in arousal, selective attention, memory, and sleep.
• Anticholinergics are linked to Increased risk of dementia.
• Alzheimer's involves destroyed neurons containing acetylcholine, leading to memory loss
• Aricept boosts acetylcholine levels.
• Insecticides increase acetylcholine.

Dopamine

• Dopamine is linked to pleasure and reward, voluntary movement, and attention.
• Parkinson's has a deficit of dopamine
• Schizophrenia symptoms have excess dopamine.

Serotonin

• Serotonin affects sleeping, eating, mood, pain, and depression
• Serotonin can be increased by eating foods rich in tryptophan, working out, or with light exposure
• Depression drugs increase serotonin availability.
• MDMA causes massive serotonin release.

Selective Serotonin Reuptake Inhibitor (SSRI)

• SSRIs treat depression by blocking the reuptake of serotonin.
• Examples: Zoloft, Prozac, Lexapro.

Neural Plasticity

• The brain is adaptable and can change.
• Myelination makes neurons faster and brain regions more efficient.
• Pruning reorganizes the brain to be more efficient by removing synaptic connections.
• Plasticity decreases in adulthood.

Intergenerational Trauma

• First observed in children of Holocaust survivors, also seen in Vietnam veterans and residential school survivors in Canada
• Assumed that trauma was passed down through environment or behavior.
• PTSD is associated with changes in brain structure, function, and chemistry, which can be passed down, making the brain more vulnerable to trauma.

Major Brain Regions

• Forebrain
• Midbrain
• Hindbrain

Hindbrain

• Reptilian/ primitive brain
• Controls basic functions like eating and sleeping.
• Major components include:
  • Medulla: vital functions like heartbeat, breathing, vomiting, blood pressure, swallowing, etc.
  • Pons: sleep & arousal.
  • Cerebellum: motor coordination.
  • Reticular Activating System: key in arousal, regulating sleep and wakefulness, and directing attention. Dysregulated in ADHD brains.

Midbrain & Forebrain

• Midbrain controls movement, relays information to seeing & hearing.
• Forebrain manages complex cognitive activities, sensory and associative functions, and voluntary motor activities.
• Major components: cerebral cortex, thalamus, hypothalamus, limbic system.

Cerebral Cortex

• The outermost layer of the brain involved in higher mental processes, such as sense, self, and reasoning
• Consists of two cerebral hemispheres (4 lobes) connected by the corpus callosum, controlling the other side of the body (contralateral).

Cerebral Cortex: Lobes

• Frontal lobe: planning, and decision making.
• Parietal lobe: sensation, somatosensory.
• Temporal lobe: auditory processing.
• Occipital lobe: vision.

Cortical Lateralization

• Cognitive function that relies more on one side of the brain than the other
• Left hemisphere is responsible for Fine-tuned language skills (Speech comprehension, production, reading, writing, etc) and Actions (Making facial expressions, Motion detection)
• RIght hemisphere is responsible for Coarse language skills (Simple speech, Simple writing, Tone of voice) and Visuospatial skills (Perceptual grouping, Face perception)

Split-Brain Surgery

• The procedure involves severing the corpus callosum to reduce the spread of epileptic seizures

Frontal Lobes

• Planning, executive functions, motor control, and sophisticated information processing.
• Broca's area is linked to language production.
• The motor cortex is responsible for body movement.
• The prefrontal cortex is for thinking, planning and language.

Phineas Gage

• Railroad foreman in Vermont, in 1848.
• A tamping iron exploded, thrusting into his head.
• It destroyed most of his left prefrontal cortex.
• He had a remarkable behavioral change following injury.

The Parietal Lobe

• It is where the somatosensory cortex is located, used for sensitivity to pressure, pain, and temperature
• Communicates information to the motor cortex every time we reach, grasp, or move our eyes.

Temporal Lobe

• The temporal lobe is responsible for hearing, understanding language, and storing autobiographical memories.
• Includes the Auditory cortex
• Includes the Wernicke's area, responsible for comprehensin

Occipital Lobe

• Occcipital lobe is specialized for vision processing and higher-order visual functions such as recognizing complex shapes Located at the back of the brain
• "Seeing stars"? Activates your visual cortex!
• Damage cause can lead to prosopagnosia or face blindness
• Damage can lead to visual agnosia

Limbic System

• Emotional center also with a role in smell, motivation, and memory.
• Hypothalamus regulates body state/ homeostasis and controls the hormonal pituitay gland
• Body temperature, hunger, and thirst
• Thalamus relays sensory information to primary cortex

Limbic System

• Amygdala plays a a role in fear, aggression, excitement and arousal Damage makes it impossible to recognize facial expressions of threat
• Hippocampus : spatial memory and storing new memories
• Memories are not stored here

Overview of Nervous and Endocrine System

• The nervous system handles primary and fast electrochemical commmunication.
• CNS: brain and spinal cord
• PNS: is sensory and motor neurons connecting the CNS to the body
• The endocrine system handles slower commmuication. Sends hormonesto bloodstream

Peripheral Nervous System

• Somatic nervous system conveys messages from the CNS and muscles.
• Autonomic nervous system controls involuntary movements of the body such as eart movement, lungs, digestion etc,
• Autonomic nervous system subdivided into sympathetic or flight and parasympathetic or rest

Autonomic Nervous System

• Autonomic nervous system divided into sympathetic nervous system or fight or flight
• Autonomic nervous system further divided into parasympathetic or rest and digest
• When one system active, the other system is inactive

Endocrine System

• Consists of series of glands that produce hormones to regulate normal bodily functions
• Involved in emotion
• Linked via the hypothalamus
• Oxycotin or Trust hormone

Endocrine Disruptors

• Natural hormones
• Endocrine disruptors

Study Findings on Microplastics in bottled water

• Microplastics in 93% of bottled water
• Studys tested 259 bottles from 11 brands across 9 countries
• Plastic discovered included polypropylene, nylon, and polyethylene terephthalate.