What was Johannes Müller (1801-1858) known for?
Doctrine of specific nerve energies. nature of a sensation depends on which neurons are active, and not on how the neurons are stimulated.
What was Charles Sherrington (1857–1952) known for?
Neurons not physically connected, but work in networks.
What was Wilder Penfield (1891–1976) known for?
Stimulating neurons in certain regions of the brain lead to patients feeling sensation of touches on their body.
What was Horace Barlow (1921 - 2020) known for?
Neuron doctrine (1972): perception depends on a combination of specialized neurons, each selective for a particular stimulus attribute
What is meant by Polysensory?
Information from several senses is combined
What is Hermann von Helmholtz (1821–1894) known for?
- Invented the ophthalmoscope
- Helmholtz argued that all behaviour could be explained by only physical forces (materialism)
- To prove this, he measured the speed of the neural impulse and proved that neurons obey the laws of physics and chemistry
What is Santiago Ramón y Cajal (1852–1934) known for?
- Created incredibly detailed drawings of neurons and neural structures
- Was the first person to discover the synapse
What is a neuron’s purpose?
Generation and transmission of electrical signals in the brain.
- Have ion channels which determine the membrane potential (neuron firing).
- Recording electrode is inside the nerve fibre.
- Null electrode is outside the fibre.
- Difference in charge between them is - 70 mV.
- This negative charge of the neurone relative to its surroundings is the resting potential.
What is meant by Threshold?
A line which dictates whether or not a stimulus is strong enough for the firing rate to be above or below the baseline rate.
*Action potential will always be the same size, what changes is the frequency
What is the Refractory Period?
a temporary state during which a cell or organ is unable to repeat an action
1 msec The upper firing rate (500-800 impulses/ AP’s per second)
What is Spontaneous Activity?
Action potentials that occur without stimulation
What machines are used for Modern Brain Electrophysiology?
(1) Electroencephalography (EEG)
(2) Event-related potential (ERP)
(3) Visually Evoked Potentials (VEP)
(4) Magnetoencephalography (MEG)
What machines are used for Brain Imaging?
(1) Computerized tomography (CT)
(2) Magnetic resonance imaging (MRI)
(3) Positron Emission Tomography (PET)
(4) Functional Magnetic Resonance Imaging (fMRI)
(5) Blood oxygen level-dependent (BOLD) signal
(6) Functional Near-Infrared Spectroscopy (fNIRS)
What is Electroencephalography (EEG)?
A technique that, using many electrodes on the scalp, measures electrical activity from populations of many neurons in the brain
What is Event-related potential (ERP)?
A measure of electrical activity from a subpopulation of neurons in response to particular stimuli that requires averaging many EEG recordings
What is Visually Evoked Potentials (VEP)?
A measure of electrical activity from a sub population of visual neurons in response to a visual stimulus.
What is Magnetoencephalography (MEG)?
A technique, similar to EEG, that measures changes in magnetic activity across populations of many neurons in the brain
What is Computerized Tomography (CT)?
An imaging technology that uses X-rays to create images of slices through volumes of material (e.g., the human body)
What is Magnetic resonance imaging (MRI)?
An imaging technology that uses the responses of atoms to strong magnetic fields to form images of structures like the brain.
What is Positron Emission Tomography (PET)?
A brain imaging method that tracks blood flow to see which areas are active, by injecting a small amount of radioactive material into the bloodstream
What is Functional Magnetic Resonance Imaging (fMRI)?
A type of MRI that measures brain activity by detecting changes in blood flow. When neurons are active, they need more oxygen, so blood flow increases. The scanner picks this up by comparing oxygen-rich and oxygen-poor blood using strong magnetic fields
What is the Blood Oxygen Level-Dependent (BOLD) signal?
The ratio of oxygenated to deoxygenated hemoglobin that permits the localization of brain neurons that are most involved in a task
What is Functional Near-Infrared Spectroscopy (fNIRS)
A non-invasive neuroimaging technique that uses near-infrared light to measure changes in brain activity by detecting variations in oxyhemoglobin and deoxyhemoglobin levels, which are closely linked to neural activity
