Neurons and Neurotransmission

• The document provides an overview of physiological psychology, addressing the mind-brain relationship, biological explanations of behavior, research techniques, genetics, and the use of animals in research. It further discusses nerve cells, nerve impulses, the role of glial cells, synaptic transmission, the nervous system's structure, and clinical applications of psychopharmacology.

The Mind-Brain Relationship

• Dualism suggests the mind and body are separate, with the mind being non-physical.
• Whereas, monism posits the mind and brain are the same, arising from physical brain activity.
• Biological psychology adopts the monistic perspective, emphasizing the material basis of thought and action.
• Consciousness is viewed as a product of brain activity.
• The "hard problem of consciousness" questions how physical processes in the brain produce subjective experiences.

Biological Explanations of Behavior

• Physiological explanations focus on the biological mechanisms underlying behavior
• Activation of the hypothalamus triggers hunger or thirst.
• Ontogenetic explanations explore the development of behavior over an individual’s lifetime
• Language acquisition involves genetic predispositions and environmental exposure.
• Evolutionary explanations examine how behaviors or traits evolve over generations; for example, fear of snakes as a survival mechanism.
• Functional explanations investigate why a behavior exists in its current form
• Bird songs serve to attract mates or defend territory.

Research Techniques to Study the Mind-Brain Relationship

• In lesion studies, observing behavioral changes after brain damage helps identify the role of specific regions
• For example, damage to Broca's area impairs speech production.
• Neuroimaging technologies like fMRI and PET scans visualize brain activity during specific tasks
• Activity in the amygdala during emotional responses.

Genetics and Behavior

• Genes influence brain structure development, neurotransmitters, and hormonal systems.
• Genes rarely act in isolation, interacting with the environment to shape behavior.
• Mendelian genetics involves single-gene traits, but most behaviors are polygenic.
• Epigenetics studies how environmental factors modify gene expression without altering the genetic code
• Early trauma can affect stress responses by altering gene activity.
• Heritability measures how much genetic variation contributes to trait differences within a population
• Intelligence and personality traits show moderate heritability but are also shaped by the environment.
• The nature vs. nurture debate is seen as a false dichotomy
• A person may inherit a predisposition for anxiety (nature), but supportive parenting (nurture) can mitigate its expression.

Animal Research

• Natural selection dictates passed-on behaviors that enhance survival and reproduction; for instance, aggression in certain contexts securing resources or mates.
• Kin selection and altruism suggest altruistic behaviors evolve, increasing survival of genetically related individuals.
• For example, a parent risking their life to save a child propagates shared genes.
• Sexual selection shows traits or behaviors evolving to increase reproductive success
• Peacocks' elaborate feathers signal health and genetic fitness.
• Evolutionary adaptations often involve trade-offs
• High anxiety may protect against threats but impair social functioning.

Ethics of Animal Research

• Animal models are critical for understanding brain-behavior relationships due to physiological and neurological similarities.
• Animal research has led to breakthroughs in treating disorders such as Parkinson's, epilepsy, and Alzheimer's.
• For example, studying dopamine pathways in rats advanced treatments for Parkinson's disease.
• Observing animal behavior helps uncover principles of learning, memory, and social interaction
• Pavlov's conditioning experiments revealed associative learning.
• Ethical considerations include minimizing animal use and ensuring humane treatment
• Abolitionists oppose all animal research as morally unacceptable.
• Institutional Animal Care and Use Committees (IACUCS) enforce ethical standards.
• Researchers must justify animal use and reduce suffering.
• As alternatives to it, computer simulations and in vitro experiments are being developed.

Neurons and Glial Cells

• The nervous system has two fundamental cell types: neurons and glial cells.
• Neurons transmit electrical and chemical signals, with excitability and specificity.
• Neurons come in sensory, motor, and interneuron varieties.
• Sensory neurons transmit information from sensory organs to the central nervous system (CNS).
• Motor neurons carry signals from the CNS to muscles/glands.
• Interneurons facilitate communication between sensory and motor neurons.
• Dendrites receive signals, the soma integrates signals, the axon transmits action potentials, and axon terminals release neurotransmitters.
• Glial cells support neuron survival and activity.

Neuron Components and Functions

Dendrites

• Branched structures extending from the soma.
• Receive electrical/chemical signals and transmit them for processing.
• Increasing neuron surface area, it allows communicationwith multiple neurons.

Soma (Cell Body)

• Contains the nucleus and organelles.
• It maintains metabolic activities.
• It integrates signals.
• If the threshold is reached, it generates outgoing signals.

Axon

• Transmits electrical impulses away from the soma.
• Serves with lengths varying micrometers to meters, as the transmission pathway.

Node of Ranvier

• Gaps in the myelin sheath along the axon.
• It facilitates saltatory conduction
• Nerve impulses "jump" from node to node for rapid signal.
• Essential for rapid transmission signal.

Axon Terminal

• Endpoints of the axon, releasing neurotransmitters into the synapse to communicate with neurons/effectors.

Schwann Cell

• Provides myelin sheath insulation in the peripheral nervous system (PNS).
• Wrapping the axon in insulation, it prevents electricalsignal loss.

Myelin Sheath

• Wraps the axon with fatty layer formed of Schwann cells.
• Enhances nerve impulse conduction insulates the axon.
• Damage can result in slower transmission or loss of function.

Nucleus

• Contains genetic material (DNA).
• Protein synthesis and cell maintenance is regulated.
• Functions by controlling cellular processes.

Interconnected Summary of Neuron Functions

• The dendrites receive input signals, the soma integrates signals, the axon generates and transmits action potentials, myelin sheath/nodes of Ranvier accelerate conduction, and axon terminals enabling communicate with neurons and target tissues.

Glial Cell Functions

• Outnumbering neurons, glia support neuron survival and activity.

Glial Cell Types

Astrocytes

• CNS glial cells maintain the extracellular environment.
• Also forming the blood-brain barrier and providing metabolic support by supplying nutrients.
• Clearing the signal post-synaptic transmission, astrocytes prevent excitotoxicity.

Oligodendrocytes (CNS) and Schwann Cells (PNS)

• Glial cells wrapping axons.
• The myelin sheath insulates axons increasing the action potential conduction.
• For example, damage in multiple sclerosis cause disrupted nerve signalling.

Microglia

• CNS immune defense cells.
• They modulate inflammation.
• For example, the overactivation can contribute to neurodegenerative diseases.

Ependymal Cells

• Lining in the cerebral Ventricles + spinal cord.
• Producing/circulating cerebrospinal fluid (CSF).

Glial Function in Neural Communication

• Non-Passive Support: contributing to neural process and synaptic modulation.
• The role in Synaptic Neurotransmission: regulating neuromodulator levels influencing synaptic strength.
• The role in Neuroplasticity: contributing to adaptation to future processes.
• The role in repair and recovery for glial cell proliferation for protecting the cerebrum.
• The role in Development: Guiding migration and synaptic connections formations.

Neuron and Glia differences

• Functionally, neurons transmits the signal
• Gila has roles in Support, maintenance, immune response.
• The signal in neurons divides rarely vs in Glia, dividing and Proliferating actively. Neuronal signal is generating and propagating action potentials, while glial signal has indirectly regulated signalling.

Dependence on glial signals

• Energy support: The astrocytes energy is supplied to help keep the Neuron functions
• Signal Enhancement: Efficiency in neural communications has been increased by the oligodendrocytes and Schwann Cells activities for increasing my electrical signals
• Neuroprotection: The Microglial Response helps clear debris and pathogens from harm.

Clinical Relevance

The following demonstrates what anatomical knowledge can be used in treating neurological diseases:

• Alzheimer's: Astrocytes and Microglia dysfunction have contributed to plaque formations and to neurodegenerations
• Multiple Sclerosis: Motor + Cognitive impairment is caused by loss of certain myelin.
• Glioblastoma: Glial tumour growth has uncontrollably caused harm from cell growth.

The Blood-Brain Barrier (BBB)

• Selective and protective layer
• Shields from harmful substances and regulates what enters the brain.
• Maintains the CNS environment.

BBB structure

• The structure is formed by the endothelial cells, astrocytes, basement membrane, pericytes
• Functions: Selective Permeability, Exclusion Of Harmful Substances, Neuroprotection.

Clinical Applications of Psychopharmacology

• Treating Depression and Schizophrenia

BBB Challenges/Limitations

• Drug delivery is limited and compromised as there are too few passages

Explore the structure and function of neurons, including axons, dendrites, and myelin sheaths. Investigate the roles of Schwann cells and axon terminals in neuronal communication. Understand the effects of damage and toxins on neural function.