tess mattson, caitlin skluzacek, blaine feia, peng jiao li, lucas menden, james loonen, chaarissa...

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TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

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Page 1: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG J IAO LI , LUCAS

MENDEN, JAMES LOONEN, CHAARISSA ROMERO

Striate Receptive Fields

Page 2: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

David Hubel and Torsten Wiesel

Wanted to extend the work done by Stephen Kuffler Used spots of light to try and map the striate cortex, which

didn’t work While trying to make the cells fire with spots, they found

that when inserting a glass slide into the ophthalmoscope, they found this made the cells fire

Realized the cells were responding to the shadow cast by the edge of the slide as it swept across the light path

Found that the cells in the striate cortex are elongated, not circular, and responded more vigorously to bars, lines, edges, and gratings

Page 3: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Orientation Selectivity

Hubel and Wiesel (1962) Uncovered a number of other important properties of the

receptive fields of neurons in striate cortex Individual neuron will not respond equivalently to just

any stripe in its receptive field Orientation tuning- tendency of neurons in striate

cortex to respond optimally to certain orientations and less to others. Ex.- Piano Keys

Page 4: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields
Page 5: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

More cells are responsive to horizontal and vertical orientations than to obliques

How are receptive fields in the LGN transformed into the elongated receptive fields in striate cortex? Hubel and Wiesel

Suggested concentric LGN cells that feed into a cortical cell are all in a row

Page 6: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields
Page 7: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

• Later studies have shown that the arrangement of LGN inputs is indeed crucial for establishing the orientation selectivity of striate cells

• However, other evidence suggests that neural interactions within the cortex also play an important role in the dynamics of orientation tuning.

Page 8: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Other Receptive-Field Properties

Respond not only to bars, lines, and edges Gratings (collections of lines)

The right spatial frequencyStriate cortex tuned to a particular frequency

Function as a filter Respond to moving lines, bars, edges, and gratings

Page 9: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Other Properties cont.

Cells influenced by input from both eyes Unlike in LGN

5-cycle/degree grating at 45 degrees Responds whether in left or right eye

Ocular dominance

Page 10: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Simple Cells

Cortical nuerons with clearly defined excitatory and inhibitory regions

Edge Detector Light on one side of receptive field and darkness on the

other sideStripe detector

Responds best by a line of light with a specific width with darkness surrounding both sides

Page 11: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Complex Cell

• A neuron whose receptive-field characteristics cannot be easily predicted by mapping with spots of light.

• A complex cell will respond regardless of where the stripe is presented, as long as it is somewhere within the cell’s receptive field

• When tested with a drifting grating, the complex cell gives a robust response, with little or none of the modulation shown by simple cells(e.g. retinal ganglion and LGN cells).

• Another way of stating this difference is to say: simple cells are “Phase-sensitive” Complex cells are “Phase-insensitive”

Page 12: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Complex

• The receptive field of complex cells represent a pooling of the response of several subunits. The subunits give the complex cell its spatial frequency and orientation tuning, but the complex pooling operation makes the complex cell insensitive to the precise position of the stimulus within its receptive field.

• Evidence shows that complex cells represent a separate parallel pathway:

Both simple cells and complex cells get direct input from LGN neurons.

Page 13: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Complex cells

• are orientation selective. • have spatially homogeneous receptive fields (no separate

ON/OFF subregions). • are nearly all binocular. • perform length summation.

Page 15: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Further Complications

End stopping These cells appear to be subclasses of the simple

and complex cells Recent Research

The size of a cell’s receptor field appears to vary with target contrast

Neurons can be influenced by stimuli that fall outside the classic receptive field

Page 16: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

Key Terms

Orientation tuning- the tendency of neurons in striate cortex to respond optimally to certain orientations and less to others

Filter- an acoustic, electrical, electronic, or optical device, instrument, computer program, or neuron that allows the passage of some frequencies or digital elements and blocks the passage of others

Ocular dominance- the property of the receptive fields of striate cortex neurons by which they demonstrate a preference, responding somewhat more rapidly when a stimulus is presented in one eye than when it is presented in the other

Simple cell- a cortical neuron with clearly defined excitatory and inhibitory regions

Complex cells- a neuron whose receptive-field characteristics cannot be easily predicted by mapping with spots of light

End stopping- the process by which a cell in the cortex first increases its firing rate as the bar length increases to fill up its receptive field, and then decreases its firing rate as the bar is lengthened further

Page 17: TESS MATTSON, CAITLIN SKLUZACEK, BLAINE FEIA, PENG JIAO LI, LUCAS MENDEN, JAMES LOONEN, CHAARISSA ROMERO Striate Receptive Fields

http://sites.sinauer.com/wolfe3e/chap3/striaterfF.htm