Parallel Processing Pathways

Question 0

What are the parallel processing pathways in the visual and cutaneous systems, and what are the advantages of having parallel pathways for processing different aspects of sensory stimuli?
Parallel processing definition

Answer 0

Parallel processing is the ability of the brain to do many things (aka, processes) at once

Question 1

What are the parallel processing pathways in the visual and cutaneous systems, and what are the advantages of having parallel pathways for processing different aspects of sensory stimuli?
Processing speed efficiency definition

Answer 1

Processing different stimuli simultaneously

Question 2

Parallel processing pathways

Retinogeniculostriate

Answer 2

1. Used by mammals for perceptual processing
2. Axons of retinal ganglion cells exit the retina via the optic nerve –> Optic nerve ends at the optic disk (region of eye)
3. Axons cross pathways to other side of the brain at optic chiasm
4. Retina is divided into two parts: nasal and temporal
5. Axons from nasal retina cross to the other side of the brain; axons from the temporal retina stay on the same side
6. When axons cross at the optic chiasm, information from the right field of view goes to the left side of the brain via the optic tract
7. They terminate in the lateral geniculate nucleus (visual part of the thalamus)–first central relay through which visual information passes onto the cortex
8. The can also terminate in the superior colliculus in the brainstem (regulates reflex orientation of eyes, neck, and head), and the suprachiasmatic nucleus in the hypothalamus

Question 3

Parallel processing pathways

Retinotectal

Answer 3

Used by fish, amphibians, and reptiles for pattern perception

Question 4

Parallel processing pathways
Cutaneous system (general)

Answer 4

Somatosensory information travels from the sensory surface to highest levels of the brain, and each sensory system has its own distinct pathway.
Pathways from receptors lead into spinal cord or brainstem.
Each station in the pathway accomplishes a basic aspect of information processing.
Sensory pathways end in the cerebral cortex, where complex processing takes place.

Question 5

Parallel processing pathways
Cutaneous system (Medial Lemniscal pathway-Pathway for touch)

Answer 5

Receptors from area touched detect stimulation of the skin and send action potentials along axons that enter into dorsal roots of spinal cord –> axon enters spinal cord dosral horn and joins the dorsal column of white matter and heads to brain –> passes through medulla, where it makes its first synapse innervating a neuron of the dorsal column nuclei –> medullary neuron sends its axon across midline and up to thalamus –> left thalamus receives info about the right side of the body –> thalamus sends info to primary somatosensory cortex

Question 6

Parallel processing pathway

Dorsal column system

Answer 6

Dorsal column system carries somatosensory information from skin to brain

Question 7

Parallel processing pathways
Lemniscal system (non-pain, epicritic)

Answer 7

One of the major sensory pathways ascending the spinal cord and into consciousness
Conducts sensitive impulses relating to touch, pressure, vibration, and joint proprioception via the dorsal funiculus and the medial lemniscus and thalamus before reaching the cortex

Question 8

Parallel processing pathways
Pain (extralemniscal pathways - pain, protopathic)
Spinothalamic pathways

Answer 8

Free nerve endings in the skin send their axons on synapse on neurons in the dorsal horn of the spinal cord.
These spinal cord neurons send their axons across the midline to the opposite side and up the anterolateral column of the spinal cord to the thalamus.
Pain information eventually integrates in cingulate cortex.

Question 9

Parallel processing pathways
Pain (extralemniscal pathways - pain, protopathic)
Neospinothalamic

Answer 9

Fast pain (direct pathway to thalamus)
Carries and processes sharp, pricking pain, and dropping temperature (cool/cold) information from the body.
The pain information carried by the neospinothalamic pathway is well localized and the sensations are short lasting "fast" or "first" pain elicited by tissue-damaging cutaneous stimuli

Question 10

Parallel processing pathways
Pain (extralemniscal pathways - pain, protopathic)
Paleospinothalamic

Answer 10

Indirect pathway

Slow pain

Question 11

Parallel processing pathways
Pain (extralemniscal - pain, protopathic)
Spinomesencephalic

Answer 11

The precise role of this pathway is uncertain.
Some believe it is responsible for initiating eye movement in response to painful stimuli.
Others suggest it represents the afferent or input side of a system which participates in the modulation of pain.

Question 12

Parallel processing pathways

Advantages

Answer 12

This parallel processing is important for reconstructing and processing our complex world and different stimuli.
Each of these channels further parses the incoming signals into parallel streams to provide a compact, efficient input to the brain.
Ultimately, these parallel input signals must be elaborated upon and integrated within the cortex to provide a unified and coherent perception.

Question 13

Parallel processing pathways

Why it’s important

Answer 13

If a patient were to come to you with loss of touch or feeling in face, or inability to feel temperature differences, you would know what pathway it is to detect the area of brain that might be damaged.
Being able to distinguish between slow and fast pain, or dull or sharp pain can help also determine pathways and area of damage.