CHapter 4 Flashcards
(51 cards)
optic chiasm
x-shaped bundle of fibers on the underside
of the brain
Each hemisphere responds to the ____, or ___, side of the visual field
opposite, contralateral
Lateral geniculate nucleus (LGN)
located in the thalamus of each hemisphere
90 percent of the signals from the retina
Neurons here have center-surround receptive fields
Purposes of the LGN is to regulate neural
information as it flows from the retina to the cortex
Receives more signals from the cortex than from the retina (feedback, “backward”
flow of information)
the information the LGN receives back from the brain may play a role in determining which information is sent up to the brain
Superior colliculus
structure involved in controlling eye movements
10 percent of the signals from the retina
The first thing that happens on the pathway to the brain is
visual signals from both eyes leave the back of the eye in the
optic nerve and meet at a location called the optic chiasm.
Second thing that happens on the pathway to the brain
Approximately 90 percent of the signals from the retina proceed to the lateral geniculate nucleus (LGN) while 10% goes to the superior colliculus
In vision and in other senses as well, the thalamus serves as
relay station where incoming sensory information often makes a stop
before reaching the cerebral cortex.
From the LGN, the visual signal then travels to the______ which is also known as____
occipital lobe, visual receiving area—the place where signals from the retina and LGN first reach the cortex (AKA Striate cortex or V1)
Hubel and Wiesel (1965) state their tactic
for understanding receptive fields as follows:
stimulate the retina with patterns of light while recording from single cells or fibers at various points along the visual pathway. For each cell, the optimum stimulus can be determined, and one can note the characteristics common to cells at each level in the visual pathway, and compare a given level with the next.
Visual Cortex Neuron Receptive Fields
Track effects of processing through different levels of visual system
See which patterns of light generate the largest response in neurons at each level
Measure activation at single cells
Note common patterns of firing within levels and between levels
A neuron’s receptive field is determined by
presenting a stimulus, such as a spot of light, to different places on the retina to determine which areas result in no response, an excitatory response, or an inhibitory response
the receptive field is always on the ____ because that is where the ____are ____.
receptor surface, stimuli , received
Cells in ___ also have excitatory and inhibitory receptive fields, but they are oriented side by side, rather than in circles
Called ___
striate cortex, simple cortical cells
The relationship between orientation and firing is indicated by a neuron’s ___
orientation tuning curve
The orientation tuning curve is
determined by_____
measuring the responses of a simple cortical
cell to bars with different orientations.
there are neurons that respond to ___ that exist in the environment.
all of the orientations
simple, complex, and
end-stopped cells fire in response to specific features of the stimulus, such as orientation or direction of movement, they have also been called____
feature detectors
simple, complex, and
end-stopped cells fire in response to specific features of the stimulus, such as orientation or direction of movement, they have also been called____
feature detectors
Relationship A:
The stimulus-perception relationship
Relationship B:
The stimulus-physiology relationship
Relationship C:
The physiology-perception relationship
To demonstrate a link between physiology and perception, it is necessary to measure
the ___
physiology–behavior relationship (C).
Selective adaptation
firing causes neurons to eventually
become fatigued, or adapt
adaptation causes two physiological
effects
1) the neuron’s firing rate decreases
2) neuron fires less when that stimulus is immediately presented again
