Biological Psychology

Introduction to Biological Psychology

Biological psychology studies the relationship between the nervous system and behaviour. Researchers in this field are known as biological psychologists or neuroscientists. This discipline bridges the gap between biological processes and psychological phenomena, providing insight into how brain activity underlies thoughts, emotions, and actions.

• Key Focus: Understanding how the brain and nervous system influence behaviour.

• Applications: Research, clinical practice, and neuropsychological assessment.

Brain Mapping Methods

Historical and Modern Techniques

Brain mapping methods are essential for understanding the structure and function of the brain. These techniques have evolved from early pseudoscientific approaches to sophisticated modern technologies.

Phrenology

• Definition: An early, now discredited, method that claimed skull shape reflected brain size and cognitive function.

• Historical Context: Popular in the 1800s, but abandoned due to lack of scientific support.

Neuropsychological Studies

• Definition: Studies of cognitive function in people with brain damage.

• Neuropsychology Tests: Assess cognitive abilities; must account for language and cultural differences.

• Animal Studies: Behavioural studies in animals with controlled brain lesions help identify brain-behaviour relationships.

Electroencephalograph (EEG)

• Definition: Measures electrical activity in the brain via electrodes on the skull.

• Strengths: Excellent for studying timing of brain activity (millisecond range).

• Limitations: Challenging to localize activity to small brain regions.

Neuroimaging Techniques

• Computed Tomography (CT): Uses X-rays to construct three-dimensional images of brain structure.

• Magnetic Resonance Imaging (MRI): Uses magnetic fields to visualize brain structure.

• Functional MRI (fMRI): Visualizes brain activity by detecting changes in blood flow.

• Positron Emission Tomography (PET): Measures consumption of glucose-like molecules to show neural activity.

• Magnetoencephalography (MEG): Measures tiny magnetic fields generated by brain activity.

Brain Stimulation Methods

• Deep Brain Stimulation (DBS): Implanted electrodes modify brain function; used to treat disorders like Parkinson's disease and depression.

• Transcranial Magnetic Stimulation (TMS): Applies magnetic fields to the skull to enhance or interrupt brain function.

Neurons: The Brain’s Communication Cells

Structure and Function of Neurons

Neurons are specialized brain cells responsible for communication within the nervous system. The human brain contains approximately 86 billion neurons, interconnected by trillions of synapses.

• Cell Body (Soma): Central part of the neuron; builds new cell components.

• Dendrites: Branchlike extensions that receive information from other neurons.

• Axons: Long tails that transmit information to other neurons.

• Axon Terminal: Knob at the end of the axon containing synaptic vesicles filled with neurotransmitters.

• Synapse (Synaptic Cleft): Space between neurons where neurotransmitters travel.

Glial Cells

Glial cells provide support and protection for neurons. They are as numerous as neurons and play vital roles in psychological functioning.

• Astrocytes: Star-shaped, most abundant; increase reliability of neuronal transmission and form the blood-brain barrier.

• Oligodendrocytes: Promote new connections and produce the myelin sheath around axons.

Neuronal Communication

Electrical and Chemical Signaling

Neurons communicate through both electrical and chemical signals. The process involves changes in membrane potential and the release of neurotransmitters.

• Resting Potential: The membrane potential when the neuron is not stimulated, typically around mV.

• Action Potential: An electrochemical impulse traveling down the axon, resulting in neurotransmitter release. It is an all-or-none response.

• Refractory Period: Brief period after firing when a neuron cannot fire again.

Synaptic Transmission

• Electrical Communication: Occurs within neurons.

• Chemical Communication: Occurs between neurons via neurotransmitters.

• Reuptake: Process by which neurotransmitters are reabsorbed into the axon terminal.

Neurotransmitters and Their Functions

Major Types of Neurotransmitters

• Glutamate: Most common excitatory neurotransmitter; involved in learning and memory. Excessive amounts may contribute to schizophrenia.

• GABA: Most common inhibitory neurotransmitter; dampens neural activity.

• Acetylcholine: Influences arousal, attention, and memory; triggers muscle movement.

• Monoamines: Includes norepinephrine (arousal, mood), dopamine (motor function, reward), and serotonin (mood, sleep).

• Anandamides: Influence eating, motivation, memory, and sleep; bind to cannabinoid receptors.

• Neuropeptides: Short strings of amino acids; endorphins relieve pain and are targeted by synthetic opioids.

Psychoactive Drugs

• Agonists: Increase activity of neurotransmitter systems (e.g., opiates mimic endorphins).

• Antagonists: Decrease activity (e.g., dopamine blockers for schizophrenia).

Neural Plasticity

Changes in the Nervous System

Plasticity refers to the nervous system's ability to change and adapt. This occurs through growth, synaptogenesis, pruning, and myelination.

• Developmental Changes: Growth of dendrites and axons, formation of new synapses, pruning of unused connections, and myelination.

• Learning: Potentiation of synapses strengthens neural pathways.

• Stem Cells: Can become any cell type, including neurons; may aid recovery from injury.

• Neurogenesis: Generation of new neurons, possible in adult brains to a limited extent.

Nervous System Organization

Central and Peripheral Nervous Systems

The nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS).

• CNS: Composed of the brain and spinal cord; processes sensory information and makes decisions.

• PNS: Nerves outside the CNS; connects the CNS to the rest of the body.

Protection of the CNS

• Meninges: Three protective layers surrounding the CNS.

• Cerebral Ventricles: Fluid-filled pockets containing cerebrospinal fluid (CSF) for protection.

Brain Structure and Function

Cerebral Cortex

The cerebral cortex is the largest part of the forebrain and is divided into four lobes, each with specialized functions.

• Frontal Lobe: Motor function, language, memory, executive functions. Includes Broca’s area (speech production) and prefrontal cortex (planning, reasoning).

• Parietal Lobe: Contains the somatosensory cortex; processes touch, pain, and temperature.

• Temporal Lobe: Hearing, understanding language, storing autobiographical memories. Includes Wernicke’s area (speech comprehension).

• Occipital Lobe: Specialized for vision.

Lateralization of Function

Certain cognitive functions are more dominant in one hemisphere than the other.

Localization and Integration

• Localization: Specific brain areas are associated with particular functions.

• Integration: Complex tasks require coordination across multiple regions.

Split Brain Surgery

• Procedure: Severing the corpus callosum to reduce epileptic seizures.

• Effect: Limits communication between hemispheres.

Subcortical Structures

Basal Ganglia

• Function: Controls movement and reward-based learning.

• Dysfunction: Linked to Parkinson’s disease.

Limbic System

• Function: Emotional processing, motivation, memory.

• Key Structures: Hypothalamus (regulates bodily states, controls pituitary gland), Thalamus (relays sensory information), Amygdala (fear, excitement), Hippocampus (spatial memory, formation of new memories).

Brain Stem

• Location: Connects cerebral cortex and spinal cord.

• Components: Cerebellum (balance, motor skills), Pons (connects cortex to cerebellum, triggers dreams), Medulla (regulates vital functions).

• Reticular Activating System: Key role in arousal; damage can result in coma.

• Midbrain: Movement, visual tracking, auditory reflexes.

Spinal Cord and Peripheral Nervous System

Spinal Cord

• Function: Transmits signals between brain and body.

• Sensory Nerves: Carry information to the brain.

• Motor Nerves: Carry information from the brain to the body.

• Interneurons: Enable reflexes.

Peripheral Nervous System

• Somatic Nervous System: Controls voluntary movement.

• Autonomic Nervous System: Controls involuntary actions; divided into sympathetic (fight or flight) and parasympathetic (rest and digestion) divisions.

Endocrine System

Hormones and Glands

The endocrine system consists of glands that secrete hormones, which regulate bodily functions and influence behaviour.

• Pituitary Gland: Controlled by the hypothalamus; releases hormones affecting growth, blood pressure, and reproduction (e.g., oxytocin).

• Adrenal Glands: Located above the kidneys; release adrenaline and cortisol during stress.

• Sexual Reproductive Glands: Testes (males) and ovaries (females); produce testosterone and estrogen.

Genetics and Behaviour

Nature vs. Nurture

• Chromosomes: Humans have 46 chromosomes (23 pairs); contain genes.

• Genotype: Genetic makeup.

• Phenotype: Observable traits.

• Dominant/Recessive Genes: Dominant genes mask recessive ones.

• Epigenetics: Gene expression can be modified by experiences.

Behavioural Adaptation and Evolution

• Adaptations: Traits that increase survival and reproduction.

• Natural Selection: Adaptations become more common in a population over time.

• Brain Evolution: Human brains have tripled in size since diverging from apes, especially in the cerebral cortex.

Behavioural Genetics

• Heritability: Percentage of trait variability due to genes.

• Highly Heritable Traits: Height, intelligence.

• Low Heritability Traits: Religious affiliation.

Behavioural Genetic Designs

• Family Studies: Examine trait similarity among relatives.

• Twin Studies: Compare identical and fraternal twins.

• Adoption Studies: Compare adopted children to biological and adoptive parents.

Additional info: This guide expands on brief points to provide a comprehensive overview suitable for exam preparation in a college-level psychology course.