Golgi and Cajal

Page 1: Overview of the Foja Mountains Expedition and Nobel Prize History

New Species Discovered

• Expedition Location: Foja Mountains, New Guinea.

• New Discoveries:

  • An unnamed Callulops frog.

  • An unnamed Albericus frog.

  • A new bird species called the smoky honeyeater.

• Researcher's Belief: The Foja Mountains may host many yet unidentified species.

Historical Context of the Nobel Prize

• Nobel Prize Established: Initiated in 1901 by Alfred Nobel, inventor of dynamite.

• Award Details:

  • One of the prizes is for Physiology or Medicine.

  • Awarding committee composed of Professors from the Karolinska Institute, Stockholm.

• Key Figures:

  • Rudolf Kölliker nominated Camillo Golgi for the 1901 prize.

  • Golgi shared the 1906 prize with Santiago Ramón y Cajal.

• Significance of 1906 Prize:

  • First Nobel Prize ever shared by two recipients.

  • Golgi provided a vital method, while Cajal delivered significant insights into brain structure.

Neuroanatomical Principles

• Functional Localization:

  • Different brain areas perform specific functions, especially within the cerebral cortex.

• Neuron Doctrine:

  • Nervous system composed of individual functional elements called neurons.

  • Neurons do not fuse but can contact each other.

Page 2: Development of the Neuron Doctrine

Early Understanding of Nervous System

• Focus of Early Microscopy: Study of peripheral nerves; hypothesized fluid carriers of signals.

• Key Microscopists:

  • Anton van Leeuwenhoek: Observed small tube-like structures.

  • Francesco Gennari: Pioneered techniques to study brain structure through frozen tissue.

Golgi’s Staining Technique

• Discovery of the Black Reaction:

  • Camillo Golgi developed a method using potassium bichromate and silver nitrate to stain nervous tissue.

  • Result: Allowed visualization of entire nerve cells and their structures.

• Impacts:

  • Enabled significant discoveries about the structure of neurons.

  • Golgi’s misinterpretation: Viewed nervous processing as a fused network.

The Evolution of Concepts

• Cell Theory Progress:

  • Recognition of the cell as a basic unit in all living things.

  • Physical separation between nerve cells was not accepted until later.

• Reticular Theory: Early theories proposed neurons were interconnected in a fused network or reticulum.

Page 3: Cajal’s Contribution and Divergent Views

Santiago Ramón y Cajal

• Initial Impressions:

  • Cajal was inspired by Golgi-stained sections of brain tissue.

  • Differentiated from previous confusion in tissue representation.

• Research Focus: Cajal utilized Golgi’s method to study cerebellar and retinal structures.

• Findings:

  • Confirmed cell types in cerebellum and identified ‘mossy’ and ‘climbing’ fibers.

Key Drawings and Concepts

• Cajal’s Illustrations:

  • Showed detailed neuron types; disagreed with Golgi on the net-like arrangement of nerves.

  • Argued for individual neurons as distinct entities.

Page 4: Cajal vs. Golgi: The Debate on Dendritic Spines

Acceptance of Cajal’s Views

• Eugenio Tanzi’s Support:

  • Acknowledged Cajal's contributions to understanding neurons' function and learning potential.

• Dendritic Spines:

  • Cajal initially faced skepticism on the existence of spines on neurons but provided evidence of their validity.

Methods and Observations

• Staining Techniques:

  • Cajal successfully demonstrated dendritic spines with methylene blue, affirming Golgi’s findings.

• Literature Impact:

  • Textbooks pre-Golgi stain lacked proper depictions of neuron structures.

  • Post-1896, spines on dendrites became a standard depiction in neural illustrations.

Page 5: Importance of Dendritic Spines and Legacy of Golgi and Cajal

Functions of Dendritic Spines

• Roles in Neuroscience:

  • Over 90% of excitatory connections made onto spines.

  • Functions attributed to spines include improving post-synaptic area, electrical resistance modulation, and involvement in learning.

• Clinical Relevance:

  • Abnormalities in spine structure or count can be linked to mental retardation.

Lasting Impact on Neuroscience

• Neuron Doctrine Evolution:

  • Cajal’s insights and Golgi’s staining technique laid foundations for modern neuroscience.

  • Establishing definitions of synapses and understanding of neuronal communication.

Final Remarks

• Cajal's legacy as a cornerstone in the field, influencing how neuroscience is studied a century later.

• Important references used to support findings include works from Tanzi, Cajal, and other historical figures in neuroscience.