Sensory systems

Question 1

Sensory modalities

Answer 1

receptors are highly specific to a type of stimulus and highly sensitive. All tuned to a specific range, eg visible light is only a small part of em spectrum.

Question 2

Transduction

Answer 2

Physical/chemical stimulus into a language that the brain understands.
Stimulus energy > receptor potential > action potentials.
The pattern of APs frequency and timing all code for properties of stimulus

Question 3

Modality pathways

Answer 3

Each modality has its own pathway, eg auditory pathway, olfactory pathway, visual pathway.

Question 4

Decomposition of the world

Answer 4

Compartmentalising the complex information of the world.
Components in each sense are analysed separately and in parallel and then recombined to encode complex features.

Question 5

Serial and parallel pathways

Answer 5

Different modalities are processed in parallel.
Stimuli are first broken down into simpler components, the reassembled.
Local and global feedback is received on all levels of processing - so ‘higher’ centres will change the information that comes in.

Question 6

Receptive field

Answer 6

An area in the periphery in which a stimulus can elicit a response. In the form of a change in the electrical activity of a sensory neuron.

Question 7

Topic maps

Answer 7

Motor and somatosensory homunculus. Visual system has retinotopic map - points in the outside world are processed and relayed.
Auditory system - tonotopic map.
All maps preserve the relationship (eg distance) of the feature that they are coding for in subsequent processing stages.
Not all maps are spatial.

Question 8

Adaptation, inhibition and feedback.

Answer 8

Adaptation - same stimulus strength will elicit less action potentials. Happens for continuous stimulus.
Inhibition from top down allows adjustments, the inhibition can be released or strengthened without a change at the receptor level.
Eg lateral inhibition, enhances borders and edges - creates contrast.