COGS 17 Lecture Notes - Lecture 3: Franz Nissl, Potassium Dichromate, Golgi'S Method
19 May 2018
School
Department
Course
Professor
Lec 2B - Eavesdropping on the mind (guest lecture)
● Anatomical exams - charting physical structures (invasive)
○ Staining
■ Cut thin layer of brain and put on slide, the dip into chemicals
■ Golgi stain - whole neuron stain - used by ramon y cajal
● Stains the soma, dendrites, and axon in brown/black
■ Ramon y cajal
● 1852-1934
● Neuron doctrine
○ Fundamental structural and functional unit is the
neuron
○ Neuron are discrete cells
○ Neurons have axon, dendrites and somas
○ Information flows on direction (dendrite → soma
→ axon)
● Shifted view from ‘reticular theory’
○ Brain is fused mesh of nerves
■ Stains random strain of portion of cells in their entirety
■ How it works: (golgi stain)
● Alternate bathing tissue in potassium dichromate and
silver nitrate
● Repetition
■ Cell body stain - nissl stain
● RAT - stains various parts of the cell body blue by
attaching a chemical die to the RNA/DNA molecules
● Allows to differentiate grey and white matter from each
other
■ Weigert stain - axons
○ Lesions
■ Insight into how the brain works
■ TAN
● Neurologist paul broca's patient
○ Only produced “tan”
○ Good comprehension
○ Broca’s aphasia → hard to produce grammatical
sentences
● Post-mortem exam revealed lesion in inferior frontal
cortex
● Area associated with language production
■ Phineas gage
● Damage to the prefrontal cortex - changes in mood and
personality
find more resources at oneclass.com
find more resources at oneclass.com
● Change in personality → became irritable, impulsive,
had trouble planning and executing complex tasks
*multiple steps*
■ Clive wearing
● Damage to the hippocampus - unable to create new
memories
■ hippocampus
● Patient HM - removed lobe to alleviate epilepsy, but left
with amnesia (also unable to create new memories)
■ Ian waterman
● Damage to proprioceptive system (neurons connected
to joints) due to the flu
■ Lesion studies: limitations
● Patients like HM and phineas gage are extremely rare
● Human brain damage is organic
○ The spatial and temporal extent is not under
experimental control
● Prior to modern imaging, localizing the lesions had to
wait until after death
● Animal research can solve some of these limitations
● Results of lesions to specific brain regions may actually
reflect a disruption in the functioning of entire systems
○ Electrical stimulation
■ Brain surgery → Must be awake for it (e.g tumor that has
spread to a large extent, need to be awake)
■ Stimulate parts of the brain and see what it affects in body -
penfield map
● Recording techniques - measuring electrical potentials (direct)
○ Single cell recording
■ Involves placing electrode on brain - thin wires
● Can pick up electrical activity of a neuron
● Usually done on animals
● Measures the difference in voltage between inside and
outside neuron (action potentials)
■ Hubel and wiesel
● Discovered ‘simple’ cells using this recording technique
● Complex cells, motion detectors, depth detectors, and
colour detectors
● Discovered ocular dominance columns
■ O’keefe and dostrovsky, 1971
● Recorded electrical activity from single neurons in the
rat as the animal freely explored an environment
● Found that single hippocampal neurons fired when the
animal was in a specific location
■ Multi-cell recording
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lec 2b - eavesdropping on the mind (guest lecture) Anatomical exams - charting physical structures (invasive) Cut thin layer of brain and put on slide, the dip into chemicals. Golgi stain - whole neuron stain - used by ramon y cajal. Stains the soma, dendrites, and axon in brown/black. Fundamental structural and functional unit is the neuron. Stains random strain of portion of cells in their entirety. Alternate bathing tissue in potassium dichromate and silver nitrate. Rat - stains various parts of the cell body blue by attaching a chemical die to the rna/dna molecules. Allows to differentiate grey and white matter from each other. Broca"s aphasia hard to produce grammatical sentences. Post-mortem exam revealed lesion in inferior frontal cortex. Damage to the prefrontal cortex - changes in mood and personality. Change in personality became irritable, impulsive, had trouble planning and executing complex tasks. Damage to the hippocampus - unable to create new memories.
