Week 1 Material Flashcards
(21 cards)
Edwin Smith Papyrus
Dates back to 1600 BC: Believed to be copied from the older text (3000-2500 BC).
Unique: • Scientific approach to medicine, not magic • Focused on trauma and surgery • 48 case studies • 27 focused on head trauma
Described cranial structures, meninges, the surface of
the brain, CSF
First record linking brain damage to deficit: Paralysis, site of injury and side of the body affected.
Hippocrates (460–370 BC): Father of Medicine, Forefather of Neurology
Magic and mysticism dominant ideology: Knowledge of anatomy critical to clinical practice.
Methods focused on:
Patient examination, inspection, palpation, auscultation.
Described the brain as two halves connected by a thin membrane: Brain = seat of intelligence, willpower, interpreted the external world.
Observed carotid artery lesions = contralateral hemiplegia: Hemiplegia = weakness, stiffness, and/or lack of control in one side of the body
Galen (129-199 AD): Founder of Experimental Physiology
Observed brain injury in gladiators:
• Noted that nerves project to and from the brain
• However, dissected and vivisected animals
• Numerous errors in human anatomy due to extrapolation.
- Focused on the ventricles:
- Four cavities = storage and distribution sites for psychic pneuma (animal spirit) throughout the CNS
Soul and higher cognitive functions:
• Located in solid regions of the brain surrounding the ventricles.
Vesalius (1514–1564): Father of Modern Human Anatomy
Mapped human anatomy through human dissection
Advocated learning anatomy through dissection of cadavers.
• Noted errors in Galen’s work:
“I myself cannot wonder enough at my own stupidity and too great trust in
the writings of Galen and other anatomists; yes, I who so much labored in
my love for Galen that I never undertook to dissect a human head in public
without that of a lamb or ox at hand, so as to supply what I could in no way
find in that of man”
De Humani Corporis Fabrica Librorum Septem (1543)
• 7 books with 200+ illustrations
Lambasted for critiquing Galen
• Only revised 2nd edition Fabrica
Gall (1758-1828) and Spurzheim (1776-1832):
Localisation of function:
• Functions linked with specific regions of the brain
Neuroanatomy dissection:
• Mapped the corticospinal tract
• Hemispheric control of contralateral movement
• The corpus callosum connected hemispheres
Phrenology (pseudoscience)
• Skull shape = personality
Described:
• Grey and white matter differentiation
• ‘Folded’ structure of the brain
Purkinje (1787-1869):
Purkinje (1837): First nerve cell described:
• Neuron type specific to the cerebellum
• Necessary for coordinated movement.
Purkinje cells:
• Characterized by:
• Extensive dendritic tree = allows for vast synaptic input.
• Single long axon
• Most release GABA (inhibitory function)
• Cell death due to ethanol = deficits in FAS
Birth of Neuropsychology
Broca (1861):
• Localisation and lateralisation of language
• Identified Broca’s area:
• Linked with speech production
• Broca’s aphasia (problems with producing speech).
Wernicke (1874): • Organisation of language: • Hearing and speech = related • Identified Wernicke’s area: • Linked with speech comprehension • Wernicke’s aphasia (impaired ability to understand language, fluent speech).
Ramón y Cajal (1852–1934): Father of Modern Neuroscience
Golgi method:
• Silver nitrate stain = nerve cells under light microscopy
• Allowed visualisation of the entire nerve cell.
Nerve cells:
• Individual elements
• Inter-connected, could touch but not fused
Discovered dendritic spines:
• Range of suggested functions:
• Increase in post-synaptic dendritic area
The Neuron Doctrine (Waldeyer-Hartz, 1891):
• Principle of separation between nerve cells
• The structure and organisation of the brain and
spinal cord.
Penfield (1891-1976): Homunculus
Penfield and Boldrey (1937):
Penfield (1928-1936): 126 patients (under local
anaesthesia)
Cortical stimulation whilst awake / report movement and sensation.
Localisation of the motor and somatosensory regions.
Acknowledged lack of histological analysis.
Functional overlap of stimulation fields: Not clear separation as detailed in the homunculus.
Goldman-Rakic (1937–2003)
Transformed research and understanding of the PFC
Multidisciplinary range of methods: New paradigm
• Biochemical, electrophysiological, pharmacological, anatomical, and behavioural techniques (non-human primates).
Discovered the cellular basis of working memory:
• Identified the dorsolateral PFC (dlPFC) = essential for spatial WM (Goldman & Rosvold, 1970)
• Delay cells = neurons activated during the delay period of a delayed-response trial (Funahashi et al., 1989).
Discovered dopamine is essential for dlPFC function:
• Cognitive deficits with dopamine depletion (Brozoski et al., 1979)
Methods and Techniques
Biological psychology uses different techniques to answer research questions:
Comparative and evolutionary psychology:
Compares human and animal behaviour and biology to explain differences or similarities.
Explains biological features or behaviours through
evolution (adaptation).
Effects of biological features or events which are not restricted to the brain or nervous system: Hormones and genes
Neuropsychology
Effects of brain damage on brain function
Investigates what damaged brains can tell us about cognition
Case studies compare brain-damaged groups with healthy controls
Brain imaging
Structural: Size (volumes), morphology (shape), regions, WM tracts.
Functional Activity:
• Haemodynamic methods
• Electro- or magneto- physiological methods
Differences between methods
Haemodynamic methods (fMRI, PET) have superior spatial resolution to electro- or magneto- physiological methods.
Electro- or magneto- physiological methods (EEG, MEG) have superior temporal resolution to haemodynamic methods.
Functional Magnetic Resonance Imaging (fMRI)
Measures oxygen in the blood
Reports this measurement as the BOLD contrast (Blood Oxygen Level Dependent): Changing concentrations of oxygenated and de-oxygenated blood, due to the difference in their magnetic properties.
Assumes a stronger signal = greater demand for
oxygenated blood: Therefore, greater activity occurring in the more oxygen-rich region.
Positron Emission Tomography (PET)
Involves injection of a radioactive tracer:
Metabolic parameters
Neurotransmission systems:
• neurotransmitter uptake/release/synthesis
• enzyme activity
• receptor/transporter availability
Neuroinflammation
Beta-amyloid deposition: Pittsburgh Compound-B (PiB) radioligand > AB42 fibrils
Concentration levels of the tracer measured.
Disadvantages:
• Radiotracer is radioactive (109 minutes half-life)
• High cost: Creation of isotopes and ligands
• Medical team/environment needed
Electroencephalography (EEG)
Electroencephalogram (EEG) records post-synaptic
voltage changes.
The column-like organisation of pyramidal cells
transmits electrical activity to the scalp.
Summation of large groups of neurons firing in
synchrony.
Volume conductor:
• Scalp, skull, brain, CSF
• = unknown location of signal generation
Magnetoencephalography (MEG)
Records magnetic fields generated by neurons: Direct measurement of neuronal activity (fMRI = indirect).
Magnetic fields detected by superconducting quantum interference devices (SQUIDs).
Signals analysed for location: Mapped onto MRI scan
Excellent temporal resolution:
• Better spatial resolution than EEG
• Magnetic fields less influenced by skull, scalp etc.
Used in combination with other methods:
• EEG, MRI, fMRI
Deep Brain Stimulation
Deep brain stimulation = implants a ‘brain pacemaker’
Pacemaker sends an electrical signal to parts of the
brain that need to be stimulated:
• Internal pulse generator – implanted under skin by
clavicle – sends out electrical pulse.
• Pulse travels up the extension to the lead
• Lead = insulated wire with electrodes implanted in to-
be-stimulated brain region
Deep Brain Stimulation Extended
Common treatment for Parkinson’s Disease and chronic pain in US.
Advantages:
Fully reversible
Precise localisation
Surprisingly few complications and side-effects
Evidence = effective for treatment-resistant depression, OCD.
Used in research:
Patients already undergoing brain surgery, e.g., for PD.
In animal studies.
Transcranial Magnetic Stimulation (TMS)
Applies magnetic field to induce electrical current: adjustable intensity.
Repetitive TMS (rTMS) = ↑ or ↓ cortical excitability:
• Low frequency (1 Hz) stimulation inhibits
• High frequency (10-20 Hz) stimulation activates
Direct current to a brain region via electrodes placed on the scalp: Battery-powered device delivers constant current (≤ 2 mA).
Anodal (positive) current stimulation:
• ↑ neuronal excitability of cortex below electrode
• neurons more likely to fire
- Cathodal (negative) current stimulation:
- ↓ neuronal excitability of cortex below electrode
- neurons less likely to fire
