Flashcards
3. Neural Processing
Cards in this deck (31)
- 1Roughly how many ganglion cells do we have in proportion to photoreceptors? (ratio)G:PR = 1:126
- 2what is the function of ganglion cells?to condense raw information from photoreceptors & select the most important info from the retinal image
- 3how do ganglion cells carry out this function? (in terms of detecting stimulus)they identify changes in patterns on light -- but simply between light and dark, NOT illumination level nor orientation of light
- 4what objective measure/experiment has helped us learn all this about retinal ganglion cells?single cell recording
- 5what approach is this fromphysiological approach
- 6who was the first test experiment for this process SCR?a cat
unethical to do it on humans - 7explain the process of single cell recordingan electrode is inserted into the axon of a singular individual neuron & its activity - nerve impulses/action potentials - are recorded
- 8what units does it recordvoltage
- 9if a neuron is active - does it increase in voltage or frequency?only frequency, voltage remains the same.
- 10how is the single cell recording experiment initially started off?where no stimulus is presented and only darkness is visible
- 11what has been found to be recorded with this?there were occasional nerve impulses fired off by ganglion cells & was not completely inactive
- 12what is this known as?the baseline activity of a ganglion cell
- 13what are other words to describe baseline activity?the activity of a ganglion cell when at rest
- 14what is the point of the single cell recording experiments?to find a stimulus that presents a change in baseline activity of ganglion cell - whether its an increase or decrease
- 15what stimulus is used for retinal ganglion cells' being recorded?light
- 16What is the receptive field?the mapped out area on a retina where, when stimulated by light, elicits a change in the firing rate of nerve impulses of the ganglion cell
- 17how many regions does it have? what are they?two regions: excitatory & inhibitory
- 18what happens if a brighter spot of light is shone on the excitatory region?increased, higher frequency in action potentials fired
- 19what about in the inhibitory regions?a further decreased rate of frequency of nerve impulses
- 20what is the effect of shining light on inhibitory regions on the baseline activity of ganglion cells?a suppression of nerve impulses -- there is a decrease in firing rate, lower than the baseline activity rate
- 21why are ganglion cells only influenced by a certain area on the retina?due to neural convergence
- 22why does this convergence create two types of response regionsdue to lateral inhibition
- 23what is lateral inhibitionwhere inhibition is transmitted laterally across the retina by horizontal and amacrine cells
- 24what is the term used to describe the organisation of receptive field regions for the retinal ganglion cellscentre-surround antagonism
- 25what are the 2 types of this organisation?on centre, off surround (+, -)
off centre, on surround (-, +) - 26why do we have such an organisation?makes it ideal for detecting spots of light, edges & boundaries between areas of light & dark
- 27what does it not detect, however?orientation of light
illumination level of light
- 28why is it important for ganglion cells to recognise this change in pattern of light & dark?carry the most !! visual info
- 29Each photoreceptor is...part of more than one ganglion cells' receptive field
- 30resulting in an overlap of...receptive fields with neighbouring ganglion cells
- 31what does this mean overall? (a statement)receptive fields of all ganglion cells together cover the whole visual field
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- Psychology (Intro to Sensation & Perception) Flashcards on 3. Neural Processing, created by Reeth G on 16/05/2024.
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