Receptive Fields of Neurons

What are the five cell types

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

What are the five cell types

• Ganglion cell (retina)

• LGN cell (thalamus)

• Simple (visual cortex)

• Complex (visual cortex)

• Hypercomplex or end-stopped (visual cortex)

Ganglion cell receptive field properties

• Small

• circular with enter-surround organization

LGN cell receptive field properties

• Small

• Circular with center-surround organization

somple cell receptive field properties

• Medium

• Bars with specific orientation

Complex cell receptive field properties

• Large

• Bars with specific orientation

• Motion

Hypercomplex or end-stopped cell receptive field properties

• Large

• Bars with specific orientation and length

• Motion

This cell responds best to a WHAT because the excitatory area of the receptive field is WHAT

This cell responds best to a 45-degree-tilted bar because the excitatory area of the receptive field is 45-degree tilted

An example of a receptive field of a WHAT cortical cell.

An example of a receptive field of a SIMPLE cortical cell.

This cell responds best to a WHAT bar of light that covers the excitatory area of the receptive field (other simple cortical cells respond best to other WHAT). This supports the viewpoint of WHAT coding).

This cell responds best to a VERTICAL bar of light that covers the excitatory area of the receptive field (other simple cortical cells respond best to other ORIENTATIONS). This supports the viewpoint of SPECIFICITY coding).

The response decreases as the bar is WHAT so that it also covers the WHAT area.

The response decreases as the bar is TILTED so that it also covers the INHIBITORY area.

Orientation tuning curve of a simple cortical cell for a neuron that responds best to a vertical bar (orientation degree = 0).

Orientation tuning curve of a simple cortical cell for a neuron that responds best to a vertical bar (orientation degree = 0).

• Many of the cells (other than the simple cortical cells) in the striate cortex and nearby visual area did not respond to small WHAT of light. The experiments by Hubel and Wiesel were fruitless. When the researchers were frustrated, something occurred suddenly. This unplanned incident caused a visual cortex neuron “went off like a machine gun.”

• When the edge of the slide dropped a WHAT responded to this motion

• Many of the cells (other than the simple cortical cells) in the striate cortex and nearby visual area did not respond to small SPOTS of light. The experiments by Hubel and Wiesel were fruitless. When the researchers were frustrated, something occurred suddenly. This unplanned incident caused a visual cortex neuron “went off like a machine gun.”

• When the edge of the slide dropped a COMPLEX CORTICAL CELL responded to this motion

Simple cortical

• WHAT and WHAT areas arranged side by side. Responds best to (WHAT) bars of a particular WHAT.

Simple cortical

• EXCITATORY and INHIBITORY areas arranged side by side. Responds best to (STATIONARY) bars of a particular ORIENTATION.

Complex cortical

• Responds best to WHAT of a correctly orientated bar across the receptive field. Many cells respond best to a particular WHAT of WHAT.

Complex cortical

• Responds best to MOVEMENT of a correctly orientated bar across the receptive field. Many cells respond best to a particular DIRECTION of MOVEMENT.

End-stopped/hypercomplex cortical

• Responds to WHAT, angles, or bars of a particular WHAT moving in a particular WHAT.

End-stopped/hypercomplex cortical

• Responds to CORNERS, angles, or bars of a particular LENGTH moving in a particular DIRECTION.

Contrast threshold

Minimum difference in intensity at which an observer can just make out the bars

Adapting to a stimulus means prolonged WHAT to a stimulus

Adapting to a stimulus means prolonged EXPOSURE to a stimulus

WHAT in contrast threshold for 0-degree orientation

INCREASE in contrast threshold for 0-degree orientation

WHAT in contrast threshold for a 20-degree orientation

NO CHANGE in contrast threshold for a 20-degree orientation

Selective adaptation

A process where the brain or sensory system REDUCE their RESPONSE to a constant, repeated stimulus while keeping sensitivity to UNADAPTED or rare features HIGH

Selective rearing

• When animals are reared in environments that contain only certain types of stimuli, neurons that respond to these stimuli will become more WHAT due to WHAT

Selective rearing

• When animals are reared in environments that contain only certain types of stimuli, neurons that respond to these stimuli will become more PREDOMINANT due to NEURAL PLASTICITY

Selective rearing - Neural plasticity (or experience-dependent plasticity)

• The response properties of neurons can be shaped by WHAT

• Environmental WHAT on physiology

• Neurons frequently in use will become WHAT; neurons not in use will be WHAT.

Selective rearing - Neural plasticity (or experience-dependent plasticity)

• The response properties of neurons can be shaped by PERCEPTUAL EXPERIENCE

• Environmental FEEDBACK on physiology

• Neurons frequently in use will become PREDOMINANT; neurons not in use will be PRUNED.

Blakemore and Cooper (1970) showed that rearing an animal in an environment that contains only vertical/horizontal lines resulted in the animal’s visual cortex having WHAT cells that respond predominantly to WHAT lines

Blakemore and Cooper (1970) showed that rearing an animal in an environment that contains only vertical/horizontal lines resulted in the animal’s visual cortex having SIMPLE cells that respond predominantly to VERTICAL/HORIZONTAL lines