Module 2

Real-Time Neural Measurement

Real-Time Neural Measurement

Measures neural activity at a rate that keeps up with the speed of the activity being monitored.

Direct Measures

Measures electrical activity of neurons.

Indirect Measures

Indicates where neurons are active but does not indicate if they are excitatory or inhibitory.

Microelectrodes

Used for measuring cell electrical potential changes.

Voltage-Sensitive Dyes

Used to measure internal chemical changes in neurons.

Electrochemistry

Technique for measuring neurotransmitter release.

Capacitance Changes

Used to measure vesicle fusion in neurons.

BOLD Signal

Blood-oxygen-level-dependent signal used in fMRI to indicate brain activity.

EMG

Electromyography, measures muscle activity and reflex contractions.

EEG

Electroencephalography, records synchronized activity from many neurons.

Transduction

The process of converting a physical stimulus into an action potential.

Ionotropic Receptors

Ligand-gated receptors that open ion channels directly.

Metabotropic Receptors

G-protein coupled receptors that indirectly affect ion channels.

Photoreceptors

Cells that enable transduction in vision, containing opsin and retinal.

Ocular Dominance Bands

Stripes in V1 that respond preferentially to input from one eye.

Orientation-Selectivity

Emergent property of cortical neurons sensitive to bar orientation.

M Pathway

Magnocellular pathway with large receptive fields, fast processing, and no color distinction.

P Pathway

Parvocellular pathway with small receptive fields, color-dependent processing.

Superior Colliculus

Multisensory structure integrating visual, auditory, and somatosensory information.

Binding Problem

Concerns how items that are encoded by distinct brain circuits can be combined for perception/decision/action

Activity-Dependent Plasticity

Neurons stabilize inputs based on activity and competition for synapses.

Receptive Fields

Areas in the visual field where a stimulus influences the firing of a neuron.

Blindsight

Ability to respond to visual stimuli without conscious perception due to V1/LGN damage.

Targeted Muscle and Sensory Reinnervation (TMSR)

Rerouting nerves to provide sensory feedback in amputees.

Phantom Limb

Sensation that an amputated limb is still present, often accompanied by pain.

How does photon capture cause a change in membrane potential of a photoreceptor?

The retinal captures a photon then dissociates, activating opsin. The activated opsin interacts with phosphodiesterase and this reduces the concentration of cGMP

Retinal ganglion cells

Respond to spots/ rings of light, but no response that relates to the orientation of a bar of light

Cortical neurons

Sensitive to bar orientation, this is an emergent property of these cells which is not present in their input neurons

Hierarchical modular organisation

Each module performs different task but works on total scope of job

Parallel modular organisation

Each module performs similar task but works on limited scope of total job

Lateral Geniculate Nucleus

visual nucleus of thalamus; relay station between retina and visual cortex; multilayered structure

Eye dominance

encoded by ocular dominance bands in V1

Orientation

Preference encoded by cortical columns in V1

Colour

Encoded by blobs

Blobs

Sections of the visual cortex where groups of neurons that are sensitive to colour assemble in cylindrical shapes

Inter-blob zone

Where neurons are not sensitive to colour (receive M pathway inputs)