biological psychology

Introductory Psychology I

Biological Psychology

  • Focuses on the relationship between the nervous system and behavior.

  • Researchers in this field are referred to as Biological Psychologists or Neuroscientists.

Brain Mapping Methods

Introduction to Brain Mapping

  • Phrenology:

    • One of the earliest brain mapping methods.

    • Belief that skull shape reflects brain size and cognitive function.

    • Discredited by mid-1800s.

Neuropsychological Studies

  • Studies cognitive functions in individuals with brain damage (part of neuropsychology).

  • Neuropsychological tests designed to assess cognitive function while considering languages and cultural influences.

  • Studies behavior in animals with controlled brain lesions also applied.

Electroencephalography (EEG)

  • Measures electrical activity of the brain with electrodes placed on the scalp.

  • Effective in studying short-term brain activity changes (milliseconds range).

  • Difficulties exist in studying small brain regions.

Neuroimaging Techniques

  • Used to visualize brain structure and functionality.

  • Computed Tomography (CT):

    • Utilizes X-rays to create three-dimensional images of the brain.

  • Magnetic Resonance Imaging (MRI):

    • Uses magnetic fields to visualize brain structure indirectly.

Functional Imaging

  • Functional MRI (fMRI):

    • Visualizes brain activity with magnetic fields.

  • Positron Emission Tomography (PET):

    • Measures glucose-like molecule consumption to provide images of neural activity.

    • Both fMRI and PET measure structure and functionality.

Additional Brain Mapping Methods

  • Magnetoencephalography (MEG):

    • Measures tiny magnetic fields generated by brain activity.

  • Deep Brain Stimulation (DBS):

    • Modifies brain function using implanted electrodes.

    • Potential applications in various disorders (e.g., Parkinson’s Disease, Depression).

  • Transcranial Magnetic Stimulation (TMS):

    • Applies rapidly changing magnetic fields to the skull's surface, which can either enhance or interrupt brain function.

Neurons: The Brain’s Communicators

  • Neurons are specialized brain cells tasked with communication.

  • Estimated 86 billion neurons exist, creating approximately 160 trillion synaptic connections.

Neuronal Components

  1. Dendrite

  2. Synapse

  3. Nucleus

  4. Soma (cell body)

  5. Action potential

  6. Myelin sheath

  7. Node

  8. Axon terminals

  9. Axon

  10. Neuron

Function of Neuron Parts

  • Cell Body (Soma):

    • Central part of the neuron responsible for building new cell components.

  • Dendrites:

    • Branch-like extensions that receive information.

  • Axons:

    • Long “tails” that transmit information away from the cell body.

  • Axon Terminals:

    • Knobs at the axon ends containing synaptic vesicles filled with neurotransmitters (NTs).

  • Neurotransmitters (NTs):

    • Chemical messengers facilitating neuron-to-neuron communication.

  • Synapse:

    • The gap between neurons through which NTs travel.

Synaptic Transmission

  • Mechanism by which signals are transmitted from one neuron to another across the synapse.

  • Key components:

    • Postsynaptic neuron surface.

    • Synaptic vesicles release NTs.

    • Nerve impulse triggers the release of NTs.

    • NTs bind to receptor sites on the postsynaptic (receiving) neuron.

Glial Cells

  • Term “glial” means glue; they support neurons.

  • Present in large quantities in the brain (1:1 ratio with neurons).

  • Types include:

    • Astrocytes:

    • Star-shaped and most abundant, increasing reliability of neuronal transmission.

    • Found primarily in the blood-brain barrier.

    • Oligodendrocytes:

    • Promote new neural connections and produce myelin sheath around axons.

Electrical Activity in Neurons

Neuronal Membrane and Potentials

  • Neuronal membranes have an electric potential that can be altered by NTs.

  • Resting Potential:

    • The membrane potential when the neuron is not being stimulated or inhibited.

  • Action Potential:

    • An electrochemical impulse that travels down the membrane, leading to NT release.

    • Requires stimulation exceeding a threshold of excitation.

Action Potential Mechanics

  • Action potentials consist of abrupt oscillations triggered by changes in ionic charge inside the axon.

  • This “firing” is subject to an all-or-none response.

  • The action potential initiates near the cell body and propagates along the axon towards the terminals, resulting in NT release.

  • Neurons can fire between 100 to 1,000 times per second.

  • Between firings, there exists a brief absolute refractory period; longer axons can limit firing rate.

Neurotransmission

  • Communication within neurons is electrical, while between neurons it is chemical.

  • Upon release, NTs bind to receptors of the following neuron in a lock-and-key fashion.

  • Reuptake:

    • The process through which NTs return to the axon terminal, terminating signal transmission.

  • NTs can be categorized by their effects: some excite while others inhibit cellular activity; each has a specific role within the brain and body systems.

Types of Neurotransmitters

  1. Glutamate

  2. GABA (gamma-aminobutyric acid)

  3. Acetylcholine

  4. Monoamines

  5. Neuropeptides

  6. Anandamides

Glutamate and GABA

  • Most common NTs in the CNS associated with learning and memory.

  • Glutamate:

    • Excitatory, enhancing neuron communication.

    • Toxic at high doses; may relate to schizophrenia and other mental disorders.

  • GABA:

    • Inhibitory, dampening neural activity.

Acetylcholine

  • Influences arousal, attention, sleep, and memory.

  • Motor neurons release acetylcholine to induce movement.

Monoamines

  • Include norepinephrine, dopamine, and serotonin; each consists of one amino acid.

    • Norepinephrine:

    • Involved in brain arousal, mood, hunger, sleep; affected by amphetamines.

    • Dopamine:

    • Related to motor function and rewards; implicated in Parkinson’s and schizophrenia.

    • Serotonin:

    • Regulates mood, temperature, aggression, and sleep cycles; key in depression treatment.

Anandamides

  • Involved in eating, motivation, memory, and sleep.

  • Bind to the same receptors as THC, the psychoactive component of marijuana.

Neuropeptides

  • Comprised of short amino acid chains.

  • Endorphins:

    • Type of neuropeptide that alleviates pain.

    • Synthetic opioids target the endorphin system (e.g., morphine).

  • Other neuropeptides help regulate hunger, learning, and memory.

Psychoactive Drugs

  • Interact with NT systems, altering mood, arousal, or behavior.

  • Agonists:

    • Enhance NT system activity (e.g., opiates mimic endorphins).

  • Antagonists:

    • Inhibit NT system activity (e.g., dopamine blockers for schizophrenia).

Neural Plasticity

Concept of Plasticity

  • Refers to the nervous system’s capacity for change.

  • Neurons adapt in four primary ways during development:

    • Growth of dendrites and axons.

    • Synaptogenesis (creation of synapses).

    • Pruning (deletion of futile synapses).

    • Myelination (formation of the myelin sheath around axons).

Changes During Learning and Repair

  • During learning, synaptic potentiation can occur, strengthening synapses.

  • Plasticity significantly decreases upon reaching adulthood; recovery from brain injury or illness may be partial.

  • Current research in stem cells shows the potential for generating new neurons, termed neurogenesis, with implications for enhanced functioning.

Brain-Behavior Network

Central Nervous System (CNS) Structure

  • Sensory input enters the CNS, while decisions are executed by it.

  • Peripheral Nervous System (PNS) consists of nerves outside the CNS.

CNS Protection

  • The CNS is safeguarded by three meninges layers.

  • Cerebral ventricles contain cerebrospinal fluid, which further protects the CNS.

Central Nervous System (1 of 2)

Organization

  • The CNS consists of anatomical regions responsible for different functions:

Cortex

  1. Frontal Lobe:

    • Executive functions, motor planning, language, and memory coordination.

  2. Parietal Lobe:

    • Processes touch and integrates sensory information.

  3. Temporal Lobe:

    • Handles auditory information, language, and memory.

  4. Occipital Lobe:

    • Specializes in visual information processing.

Basal Ganglia

  • Controls movement and motor planning.

Limbic System Components

  • Thalamus: Message relay of sensory information.

  • Hypothalamus: Oversees endocrine and autonomic functions.

  • Amygdala: Manages arousal and fear responses.

  • Hippocampus: Responsible for spatial memory processing.

Cerebellum

  • Manages balance and coordinated movement.

Brain Stem Functions

  • Relays signals between the cortex and spinal cord.

  • Involves midbrain, pons, and medulla.

Central Nervous System (2 of 2)

  • The CNS, particularly the brain, is subdivided into systems based on functional locations.

Cerebral Cortex

Structure

  • Major portion of the forebrain consisting of four lobes with distinct functions.

  • Contains two hemispheres linked by the corpus callosum, enabling interhemispheric communication.

Lateralization

  • The degree to which cognitive functions rely more heavily on one hemisphere than the other.

Lateralized Functions

Left Hemisphere

Right Hemisphere

Fine-tuned language skills

Coarse language skills

Speech comprehension

Tone of voice

Speech production

Motion detection

Reading

Visuospatial skills

Writing

Perceptual grouping

Brain Functionality

  • Certain brain areas are linked to specific functions (localization of function).

  • However, complex tasks require the coordinated efforts of various regions.

Split-Brain Surgery

  • A procedure where the corpus callosum is severed to reduce epilepsy.

Frontal Lobes

Functions

  • Essential for motor function, language processing, and memory organization.

  • Contains:

    • Broca’s Area:

    • Critical for speech production.

    • Motor Cortex:

    • Generates signals for voluntary movements.

    • Prefrontal Cortex:

    • Involved in planning and decision-making.

Associated Areas

  • Somatosensory Cortex: Processes skin, muscle, and joint sensations.

  • Visual Association Cortex: Analyzes visual data to create imagery.

  • Wernicke's Area: Responsible for interpreting spoken and written language.

  • Primarily Auditory Cortex: Detects basic sound qualities like pitch.

Case Study: Phineas Gage

  • A railroad foreman involved in a severe accident (1848) that damaged his left prefrontal cortex.

  • Resulted in significant personality changes, making him “no longer Gage”.

Parietal Lobe

Functions

  • Houses the Somatosensory Cortex, sensitive to various sensations (pressure, pain, temperature).

  • Coordinates sensory input with motor signals facilitating movement tasks.

Temporal Lobe

  • Positioned in the lower cerebral cortex; integral for hearing, language comprehension, and managing autobiographical memory.

  • Host to the Auditory Cortex and Wernicke’s Area, impacting speech comprehension.

  • Lesions can lead to cognitive functional losses, such as neglect.

Occipital Lobe

  • Exclusively specializes in processing visual information, located at the posterior part of the brain.

Cortical Hierarchies

  • Sensory information reaches the primary sensory cortex before advancing to the association cortex, culminating in a hierarchical processing model that increases in complexity.

Basal Ganglia

Roles

  • Structures within the forebrain that regulate movement and facilitate reward-based actions.

  • Damage can lead to movement disorders such as Parkinson's disease.

Limbic System

Overview

  • Regarded as the emotional center of the brain, playing roles in olfaction, motivation, and memory.

  • Components include the Hypothalamus (regulates bodily states, controls the pituitary gland), Thalamus (sensory information relay), Amygdala (involved in fear and excitement), and Hippocampus (crucial in forming new memories and spatial navigation).

Brain Stem

Structure and Function

  • Located at the brain’s posterior aspect, it connects the cortex with the spinal cord and oversees fundamental body functions.

  • Comprises:

    • Cerebellum: Coordinates movement and balance.

    • Pons: Acts as a conduit for information transfer between cortex and cerebellum; involved in dream regulation.

    • Medulla: Manages autonomic function such as breathing and heartbeat.

Reticular Activating System

  • Connects with forebrain and cortex, significant for arousal management; damage may lead to a coma.

  • The midbrain facilitates movement and visual tracking; also involved in reflexes triggered by auditory stimuli.

Spinal Cord

  • A crucial nerve bundle conveying signals between the brain and body.

  • Sensory Nerves: Relay information from the body to the brain.

  • Motor Nerves: Relay information from the brain to muscles.

  • Also houses Interneurons, which facilitate reflex actions.

Peripheral Nervous System (PNS)

Structure and Division

  • Comprised of nerves extending beyond the CNS and divided into two branches:

    • Somatic Nervous System: Directs voluntary muscle movements.

    • Autonomic Nervous System: Regulates involuntary actions of organs and glands, further split into:

    • Sympathetic Division: Engages during crises (fight or flight).

    • Parasympathetic Division: Manages rest and digestive processes.

Endocrine System

Overview

  • Established system of glands and hormones controlling chemical messengers in blood.

Hormonal Functions

  • Hormones influence organ functionalities and emotions.

Pituitary Gland

  • Regulated by the hypothalamus; governs performance of other glands.

  • Secretes hormones impacting growth, blood pressure, and more.

  • Includes Oxytocin: Involved in reproductive functions and critical to social bonding (mother-child attachment; romantic love).

Adrenal Glands

  • Located atop the kidneys; act as centers for emergency response by releasing adrenaline and cortisol during stress.

  • Adrenaline: Increases energy production in muscle cells; reduces it in other cell types.

  • Cortisol: Influences blood pressure, cardiovascular health, and the metabolism of proteins, carbohydrates, and fats.

Sexual Reproductive Glands

  • Testes (males) & Ovaries (females): Produce sex hormones including testosterone and estrogen.

Nature (Genes) vs Nurture (Environment)

Genetic Composition

  • Chromosomes within each cell (46 total: 23 from each parent) hold genes that dictate traits.

  • Genotype: Genetic makeup.

  • Phenotype: Observable characteristics derived from genotype.

Gene Dynamics

  • Genes can be dominant (masking others) or recessive (masked).

  • Gene expression is subject to environmental influences (epigenetics).

Behavioral Adaptation

Concept

  • Adaptations enhance survival and reproduction effectiveness in specific environments.

  • Fitness: The tendency of organisms to survive and reproduce at greater rates than others in their population.

  • Natural Selection: Process by which beneficial adaptations increase in frequency among populations.

Evolution of the Brain

Human Brain Development

  • The human brain size has tripled since divergence from the common ancestor of humans and apes 6-7 million years ago.

  • The cerebral cortex has undergone the greatest changes, correlated with higher intelligence.

Behavioral Genetics

Overview

  • Examines nature vs. nurture impacts on psychological traits.

  • Heritability: The percentage of trait variability across a population due to genetic influence.

  • Traits have varying heritability (e.g., height is highly heritable; religious affiliation has low heritability).

Behavioral Genetic Designs

Study Methods

  • Family Studies: Investigate trait heritability within familial contexts.

  • Twin Studies: Compare traits in identical and fraternal twins to assess genetic versus environmental influences.

  • Adoption Studies: Evaluate traits in adoptees to separate genetic and environmental factors impacting development.