Ch 11: Localizing stimuliand orienting in space Flashcards
What is the spatial receptive field of a cell?
The spatial receptive field of a cell is the region of physical space in which stimuli elicit robust neuronal responses
Is the 2-point threshold in the fingers, face and toes higher or lower than in the rest of the body?
LOWER.
Lower threshold = more accurate!
Sensory axons innervating the skin of the trunk and limbs ascend through the ___ ___ and terminate in the __ ___ ___, whose axons CROSS TO THE OTHER SIDE and ascend to the ___ ____ ____ ____.
Sensory axons innervating the skin of the trunk and limbs ascend through the SPINAL CORD and terminate in the DORSAL COLUMN NUCLEI, whose axons CROSS TO THE OTHER SIDE and ascend to the THALAMIC VENTRAL POSTERIOR NUCLEUS (VPN)
Axons innervating facial skin project to the ____ ____ ____, which projects to a more medial portion of the _____ ____.
Axons innervating facial skin project to the PRINCIPAL TRIGEMINAL NUCLEUS, which projects to a more medial portion of the CONTRALATERAL VPN.
Information from the trunk, legs, and face converge in the ____
Ventral posterior nucleus (VPN)
Where is converging somatosensory information sent to from the VPN?
From the VPN information is sent to the PRIMARY SOMATOSENSORY CORTEX (S1)
What is somatosensory homunculus and how was it generated?
Somatosensory homunculus is a distorted representation of the human body based on a neurological map of the areas and proportions of the brain dedicated to processing sensory info for different parts of the body.
It was discovered by Penfield, who analyzed SKIN SENSATIONS evoked by ELECTRICAL STIMULATION of the SOMATOSENSORY CORTEX.
What two areas are overrepresented in the somatosensory homunculus?
face and hands
What is the “barrel cortex” of rodents?
- Barrel-shaped clusters of cells in a rat’s somatosensory cortex.
- Each cortical barrel contains neuronal cell bodies and processes sensory information from a specific whisker on a rodent’s snout.
- arranged in columns like on the snout
rat’s whiskers are represented ______ in the barrel cortex
topographically
Define lateral inhibition
The tendency for excited neurons to inhibit their neighbours.
How does lateral inhibition allow for more precise stimulus localization in S1?
Neurons that are strongly excited by stimulation on one spot on the skin supress neighbouring neurons that are weakly excited. This sharpens the edges of the stimulus representation within the somatosensory map.
in the visual system, which region of space is overrepresented?
the region of space at which your fovea is aimed, because it has the highest density of photoreceptors.
Define “visual field” and what is the center of the visual field?
Visual field is the region of space from where a visual stimuli can reach your retina.
The center of the visual field is the location where the foveae are aimed.
What are the retina’s output cells?
retinal ganglion cells
The ____ ____ plays a major cole in eye movements
the SUPERIOR COLLICULUS plays a major role in eye movements
The ___ ___ ___ sends projections to the primary visual cortex (V1)
The LATERAL GENICULATE NUCLEUS (LGN) sends projections to the primary visual cortex (V1)
Damage of V1 on the left side of the brain in human causes blindness where?
in the RIGHT VISUAL HEMIFIELD.
Define right visual hemifield
the visibe region of space that lies to the right of the FIXATION POINT, where the foveae are aimed
The retinal axons cross at the ___ ___
optic chiasm
T/F: lesions of V1 on one side of the brain causes blindness in portions of BOTH EYES
TRUE.
V1 damage on the right side of the brain causes blindness in the left visual hemifield, and damage on the left side causes blindness in the right visual hemifield
Information from the right visual hemifield is sent to the ___ ___ ___ and ___ ___, while info from the left visual field is sent to the ____ side of the brain.
Information from the right visual hemifield is sent to the LEFT LATERAL GENICULATE and VISUAL CORTEX, while info from the left visual field is sent to the RIGHT side of the brain.
Do the axons from the temporal retina cross?
The axons from the temporal retina enter the optic chiasm BUT REMAIN UNCROSSED
Which retinal axons cross to the other side of the brain in humans and primates?
Only the axons from the NASAL PORTION OF EACH RETINA cross to the other side of the brain