The Biological Perspective - Psychology: An Exploration

Neurons and Neurotransmitters

  • Nervous System: Network carrying information throughout the body.
  • Neuroscience: Study of the brain, neurons, nerves, and nervous tissue.
  • Biological Psychology: Focuses on biological bases of behavior and learning.

Structure of a Neuron

  • Neuron: Basic cell of the nervous system.
    • Dendrites: Receive messages.
    • Soma: Cell body, maintains cell life.
    • Axon: Carries neural message to other cells.
    • Axon Terminals: Communicate with other nerve cells.
  • Glial Cells: Support neurons, deliver nutrients, clean waste, produce myelin.
    • Myelin: Fatty substance insulating axons, speeding up neural impulses.

Neural Impulse

  • Ions: Charged particles.
    • Inside neuron: negatively charged.
    • Outside neuron: positively charged.
  • Diffusion: Ions move from high to low concentration.
  • Resting Potential: Neuron not firing.
  • Action Potential: Reversal of charge that travels down the axon, releasing neurotransmitters.
    • Positive sodium ions enter the cell through ion channels.
  • All-or-None: Neuron either fires completely or not at all.

Neurotransmission

  • Synaptic Vesicles: Sacs containing neurotransmitters.
  • Neurotransmitter: Chemical affecting the next cell.
  • Synapse/Synaptic Gap: Space between axon terminals and dendrites of next cell.
  • Receptor Sites: Proteins on dendrites shaped for specific neurotransmitters.
  • Excitatory Synapse: Neurotransmitter causes receiving cell to fire.
  • Inhibitory Synapse: Neurotransmitter causes receiving cell to stop firing.
  • Agonists: Mimic/enhance neurotransmitter effects.
  • Antagonists: Block/reduce cell response to neurotransmitters.
  • Reuptake: Neurotransmitters taken back into synaptic vesicles.
  • Enzyme: Complex protein that alters neurotransmitter structure.
    • Enzymatic Degradation: neurotransmitter is altered so it can no longer act on a receptor

Key Neurotransmitters

  • Acetylcholine (ACh): Arousal, attention, memory, muscle control.
  • Norepinephrine (NE): Arousal and mood.
  • Dopamine (DA): Movement control, pleasure sensations.
  • Serotonin (5-HT): Sleep, mood, anxiety, appetite.
  • GABA: Inhibitory, involved in sleep and movement.
  • Glutamate: Excitatory, involved in learning and memory.
  • Endorphins: Pain relief.

Studying the Brain

Methods for Studying the Brain

  • Lesioning Studies: Destroying brain cells to study the impact.
  • Brain Stimulation: Using electrical current to stimulate neurons.
    • Electrical Stimulation of the Brain (ESB): Milder currents to activate neurons.
    • Deep Brain Stimulation (DBS): Impulses to implanted electrodes.
    • Transcranial Magnetic Stimulation (TMS): Magnetic pulses applied to the cortex.

Noninvasive Brain Techniques

  • Repetitive TMS (rTMS)
  • Transcranial Direct Current Stimulation (tDCS)

Optogenetics

  • Modifying genes of neurons so they are sensitive to light and then using light devices inserted in the brain to modify the activity of those neurons

Neuroimaging Techniques

  • Computed Tomography (CT): Computer-controlled X-rays.
  • Magnetic Resonance Imaging (MRI): Radio waves and magnetic fields for detailed images.
    • MRI Spectroscopy: Estimates concentration of chemicals and neurotransmitters.
  • Diffusion Tensor Imaging (DTI): Uses MRI to estimate the location and orientation of the brain’s white matter tracts.
  • Electroencephalogram (EEG): Records electrical activity using scalp electrodes.
  • Magnetoencephalography (MEG): Detects magnetic fields generated by neuron activity.
  • Positron Emission Tomography (PET): Radioactive sugar injected to map brain activity.
  • Functional MRI (fMRI): Creates "movie" of brain activity changes over time.
  • Near-Infrared Spectroscopy (NIRS): Measures blood oxygen levels in the brain.

Brain Structures and Functions

The Hindbrain

  • Medulla: Life-sustaining functions (breathing, heart rate).
  • Pons: Sleep, dreaming, coordination.
  • Reticular Formation (RF): Selective attention.
  • Cerebellum: Fine motor movement.

Limbic System

  • Involved in emotion, learning, memory, and motivation.
  • Thalamus: Relays sensory information to the cortex.
  • Hypothalamus: Motivational behavior (sleep, hunger, thirst, sex).
  • Hippocampus: Formation of long-term memories.
  • Amygdala: Fear responses and memory of fear.
  • Cingulate Cortex: Cognitive and emotional processing.

Cortex

  • Higher thought processes and sensory input interpretation.
  • Occipital Lobe: Visual processing.
    • Primary Visual Cortex: Processes visual information from the eyes.
    • Visual Association Cortex: Identifies and makes sense of visual information
  • Parietal Lobe: Touch, taste, temperature sensations.
    • Somatosensory Cortex: Processes information from skin and internal body receptors.
  • Temporal Lobe: Hearing and speech.
    • Primary Auditory Cortex: processes auditory information from the ears
    • Auditory Association Cortex: identifies and makes sense of auditory information
  • Frontal Lobe: Higher mental processes, decision-making, speech.
    • Motor Cortex: Sends commands to muscles.

Association Areas of the Cortex

  • Coordination and interpretation of information.
  • Broca’s Aphasia: Inability to speak fluently due to damage in Broca's area.
  • Wernicke’s Aphasia: Inability to understand language due to damage in Wernicke's area.
  • Spatial Neglect: Failure to recognize objects in the left visual field due to damage in right hemisphere.

Cerebral Hemispheres

  • Left Hemisphere: Language, logic, math, sequential processing.
  • Right Hemisphere: Emotional expression, spatial perception, global processing.

The Nervous System

Components

  • Central Nervous System (CNS): Brain and spinal cord.
    • Spinal Cord: Carries messages to and from the body to the brain that is responsible for very fast, lifesaving reflexes
  • Peripheral Nervous System (PNS): Nerves and neurons outside the brain and spinal cord.

Neurons

  • Sensory Neuron (Afferent): Carries information from senses to CNS.
  • Motor Neuron (Efferent): Carries messages from CNS to muscles.
  • Interneuron: Connects sensory and motor neurons in the spinal cord.

Reflex Arc

  • Connection of afferent neurons to the interneurons to the efferent neurons, resulting in a reflex action

Neuroplasticity

  • constant change both the structure and function of cells in response to experience or trauma

Peripheral Nervous System (PNS)

  • Somatic Nervous System: Voluntary muscle control.
    • Sensory Pathway: nerves carrying messages from the senses to the CNS
    • Motor Pathway: nerves coming from the CNS to the voluntary muscles
  • Autonomic Nervous System (ANS): Involuntary muscle, organ, and gland control.
    • Sympathetic Division: Reacts to stress (fight-or-flight).
    • Parasympathetic Division: Restores body to normal functioning.

The Endocrine System

Glands and Hormones

  • Endocrine Glands: Secrete hormones into the bloodstream.
  • Hormones: Affect behavior and emotions.

Pituitary Gland

  • Master gland, secretes growth hormone, influences other glands.
  • Oxytocin: Reproductive and parental behaviors.
  • Vasopressin: Controls water levels.

Other Endocrine Glands

  • Pineal Gland: Secretes melatonin.
  • Thyroid Gland: Regulates metabolism.
  • Pancreas: Controls blood sugar levels.
  • Gonads: Sex glands (ovaries and testes).
  • Adrenal Glands: Stress response, salt intake, secondary source of sex hormones.

Hormones and Stress

  • Autonomic Nervous System (ANS): Controls involuntary functions.
    • increased heart rate
    • slowed digestion
    • surge of energy to the muscles

General Adaptation Syndrome (GAS)

  • Alarm: Sympathetic nervous system activation.
  • Resistance: Body tries to sustain, but stress symptoms persist
  • Exhaustion: Resources depleted, leading to disease.
    • resources have been depleted
    • can lead to disease, weakened immune system, or death
  • Immune System: Responds to diseases and injuries.

Psychoneuroimmunology

  • Study of psychological factors on the immune system.
  • Allostasis: Maintaining stability through change.
  • Allostatic Load: Prolonged exposure to stress hormones, causing wear and tear.

Health Impacts of Stress

  • Heart Disease: Increased risk of coronary heart disease (CHD).
  • Diabetes: Type 2 diabetes associated with weight gain.
  • Cancer: Increased malfunction of natural killer (NK) cells.