Psych 267 Flashcards Up To Midterm 1 Ppt 4

Front 1

Geniculo-striate Pathway

Back 1

Each eye receives inout from the left and right visual field. Temporal visual field projects to nasal retinal. Nasal visual field projects to temporal retina. Nasal retinal fibres cross over at optic chiasm and project to lateral geniculate nucleus.

Front 2

Lateran Geniculate Nucleus (LGN)

Back 2

Has 6 layers 1,4,6: Contralateral eye. 2,3,5: Ipsilateral eye.

Front 3

M channel

Back 3

Motion contrast

Front 4

P channel

Back 4

Colour, fine details.

Front 5

K channel

Back 5

Blue, Motion

Front 6

Neural Processing within the LGN

Back 6

It receives approximately 90% of the fibres from the retina. 10% goes to the superior colliculus. LGN neurons have centre surround receptive fields. LGN regulates neural signals en-route to the visual cortex.

Front 7

How the LGN regulates neural signals en-route to the visual cortex

Back 7

It combines inputs from various sources to regulate neural firing. Feedback projections from V1. 10 Action potentials from the retina is equal to 4 action potentials to the V1

Front 8

Retinotopic organization in the visual system

Back 8

The visual system is organized retinotopically. Each portion of the retina is represented on a topographic map at multiple levels of the geniculo-striate system. Damage to a piece in the map will result in blindness for the corresponding area.

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Front 10

Cellular Organization of visual cortex

Back 10

The primary visual cortex (V1) is the first cortical region that receives visual information from the retina. Often referred to as the Striate cortex because of distinct stripe pattern (in V2). Cortex has 6 layers. Layer 4 receives sensory inputs.

Front 11

Receptive fields of V1 neurons

Back 11

Simple cells. Neurons respond maximally when the stimulus is in the preferred orientation. Orientations selectivity. Different neurons respond to different orientations. V1 Neurons as feature detectors.

Front 12

Simple cells

Back 12

Have side by side opponent receptive fields. Monocular receptive fields.

Front 13

Complex cells

Back 13

Respond best to bars at a particular orientation that move in a specific direction.

Front 14

End Stopped Cells

Back 14

Fire when lines of a specific length move in a particular direction. Also respond to moving edges or angles.

Front 15

Cortical Magnification

Back 15

Fovea accounts for approximately 0.01% of the area of the retina. However 10% of the visual cortex is devoted to the fovea.

Front 16

The role of feature detectors in vision

Back 16

Linking firing rates with perception. Selective adaptation and the contrast threshold.

Front 17

Linking firing rates with perception

Back 17

Selective adaptation. Neurons that respond to a particular property will fatigue if they are continuously exposed to the same stimulus.

Front 18

Selective adaptation and the contrast threshold

Back 18

Difference in intensity needed so that the bars are barely visible.

Front 19

Selective rearing experiments

Back 19

Cats were raised in environments with only horizontal or vertical stripes for 5 hours a day for 5 months. V1 neurons responded only to line orientations that were consistent with the environment that the cat was raised in.

Front 20

Columnar organization of V1

Back 20

Location columns, Orientations columns, Ocular dominance columns, Hypercolumns.

Front 21

Location Columns

Back 21

Columns whose receptive fields are concentrates in the same part of the retina.

Front 22

Orientation Columns

Back 22

Columns whose receptive fields prefer a specific orientation (tied to location columns)

Front 23

Ocular dominance columns

Back 23

Columns whose receptive fields are predominately from one eye.

Front 24

Hypercolumns

Back 24

Columns that combine location specificity, orientation selectivity, and ocular dominance. Ice cube model.

Front 25

Hypercolumns in V1

Back 25

Each region of visual space is represented by a V1 module. Blobs are sensitive to colour but not orientation or form. Colour information sent to V4/V8. Neurons outside of blobs respond to orientation and form but not colour.

Front 26

Representations of Objects in V1

Back 26

Objects activate numerous hypercoloumns in V1 that correspond to stimulated portions of the retina. Features of the objects are coded by simple, complex, and end-stop cells in each of the hypercolumns.

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Front 28

Object discrimination

Back 28

Monkey has to remember under which object the food is placed. Inferior temporal lesions cause a deficit. 'what'.

Front 29

Landmark Discrimination

Back 29

Monkey has to remember that the food is in hidden under the object that is near the cylinder. Parietal lesions cause a deficit. 'where'.

Front 30

Patient DF: Visual form agnosia

Back 30

Bilateral lesions to the occipital-temporal cortex. She could not recognize objects or copy simple drawings. She could draw items from memory.

Front 31

Dorsal

Back 31

Fast response. M-channel. Absolute metrics. Moment to moment. Visually guided action. 'non-conscious'.

Front 32

Ventral

Back 32

Slow response. M+P channels. Scene based metrics. Long term memory. Object recognition. 'Conscious'.

Front 33

Patient D.B. and 'blindsight'

Back 33

34 yr old male, began experiencing migraine headaches at 14. Visual auras were present prior to headaches which developed into a scotoma on the patients left side. D.B. was still able to localize targets in his blind field.

Front 34

Alternate visual pathways

Back 34

Visual information can reach the cortex outside of the primary visual pathway.

Front 35

Organization of the ventral stream

Back 35

There are regions outside occipital cortex that are specialized for processing different kinds of visual information.

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Front 37

Prosopagnosia

Back 37

The inability to recognize faces despite normal perceptual abilities. Cannot even recognize their own family members. Recognize people using voices, hair, posture. Caused by lesions to the right fusiform gyrus (FFA)

Front 38

Congenital Prosopagnosia

Back 38

Ventral stram areas must develop over time in order to correctly recognize objects and faces.

Front 39

Category learning and the ventral stream

Back 39

Cells in area TE respond to complex combinations of object features. Cells with similar selectivity are clustered together in columns. Object identification requires activation of many neurons in a column. These neurons are shaped by learning.