Sensory system

From Freepedia

(See also sense)

A sensory system is a part of the nervous system that consists of sensory receptors, neural pathways, and those parts of the brain responsible for processing the information. Specific sensory systems are those for vision, hearing, somatic sensation, taste and olfaction.

1 Functions
- 1.1 Coding
  - 1.1.1 Modality
2 Human sensory system

Functions

Receptive fields have been identified for the visual system, auditory system and somatosensory system, so far.

Coding

Sensory systems code for four aspects of a stimulus; type (modality), intensity, location, and duration.

Modality

There are many stimulus modalities; temperature, taste, sound, pressure. The type of sensory receptor activated by a stimulus plays the primary role in coding the stimulus modality.

In the Memory-prediction framework, Jeff Hawkins mentions a correspondence between the six layers of the cortex and the six layers of the optic tract of the visual system. The Primary visual cortex has areas labelled V1, V2, V3, V4, V5, MT, IT, etc.

Hawkins then lays out a scheme for the analogous modalities of the sensory system. In particular, there will be cells which can be labelled as belonging to V1, V2, etc., A1, A2, etc.:

V1

Visual Area 1, etc. for vision, via the visual system to the primary visual cortex.

A1

Auditory Area 1, etc. for hearing, via the auditory system, the primary auditory cortex.

S1

Somatosensory Area 1, via the somatosensory system for touch and proprioception. The somatosensory system feeds the primary somatosensory cortex#Brodmann Areas 3, 1 and 2. But there are also pathways for proprioception (via the cerebellum), and motor control (via Brodmann area 4).

G1

Gustatory Area 1, etc. for taste.

O1

Image:Sue'sBrain.jpg Olfactory Area 1, etc. for smell (olfaction). In contrast to vision and hearing, the olfactory bulbs are not cross-hemispheric; the right bulb connects to the right hemisphere and the left bulb connects to the left hemisphere.