Limits...
Development and matching of binocular orientation preference in mouse V1.

Bhaumik B, Shah NP - Front Syst Neurosci (2014)

Bottom Line: At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective.The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells.It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels.

View Article: PubMed Central - PubMed

Affiliation: Electrical Engineering Department, Indian Institute of Technology Delhi New Delhi, India.

ABSTRACT
Eye-specific thalamic inputs converge in the primary visual cortex (V1) and form the basis of binocular vision. For normal binocular perceptions, such as depth and stereopsis, binocularly matched orientation preference between the two eyes is required. A critical period of binocular matching of orientation preference in mice during normal development is reported in literature. Using a reaction diffusion model we present the development of RF and orientation selectivity in mouse V1 and investigate the binocular orientation preference matching during the critical period. At the onset of the critical period the preferred orientations of the modeled cells are mostly mismatched in the two eyes and the mismatch decreases and reaches levels reported in juvenile mouse by the end of the critical period. At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective. In literature around 40% cortical cells are reported as orientation selective in mouse V1. The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells. The absence of near neighbor interaction among cortical cells during the development of thalamo-cortical wiring causes a salt and pepper organization in the orientation preference map in mice. It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels.

No MeSH data available.


Related in: MedlinePlus

(A) HWHH histogram for the cells in a 35 × 60 patch from the binocular region in the cortex. The histograms are shown from 500 to 3000 epochs at an interval of 500 epoch. (B) Histograms of preferred orientation difference between the two eyes at (i) 500, (ii) 1500, and (iii) 2500 epochs. In (iv) the histograms in (i)–(iii) are compared with uniform distribution (green line). Uniform distribution is the expected distribution of /ΔOR/ when the left and right receptive fields develop independently. At 500 epochs, /ΔOR/ distribution is almost uniform. There is not much improvement in /ΔOR/ between 1500 and 2500 epochs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4109519&req=5

Figure 7: (A) HWHH histogram for the cells in a 35 × 60 patch from the binocular region in the cortex. The histograms are shown from 500 to 3000 epochs at an interval of 500 epoch. (B) Histograms of preferred orientation difference between the two eyes at (i) 500, (ii) 1500, and (iii) 2500 epochs. In (iv) the histograms in (i)–(iii) are compared with uniform distribution (green line). Uniform distribution is the expected distribution of /ΔOR/ when the left and right receptive fields develop independently. At 500 epochs, /ΔOR/ distribution is almost uniform. There is not much improvement in /ΔOR/ between 1500 and 2500 epochs.

Mentions: For binocular RF development prior to the critical period, we use Equation (1) till 500 epochs. We start the iteration with very small (of the order of 10−6) random values of synaptic weights. Due to reaction term, the weights quickly increase and observable responses from cells with orientation tuning start from 500 epochs onward. A significant number (approximately 20%) cells display orientation tuned monocular responses at 500 epochs. But as the receptive field in two eyes develop independently, only 4% cells have both tuned left and right monocular responses with absolute value of /OD/ < 0.8 and maximum spike rate in left and right monocular responses greater than 3 spikes/s (baseline firing rate of cortical cells). Experimentally oriented cells are observed at the start of critical period (Wang et al., 2010). In our simulation we take 500 epochs as the start of the critical period. We develop synaptic weight using Equation (2) from 500 to 3000 epochs. Histogram of HWHH of binocular cells is shown in Figure 7A starting from 500 epochs to 3000 epochs at an interval of 500 epochs. With increase in epochs the number of binocular orientated cells increases from 4% at 500 epochs to 39% at 3000 epochs. The increase in number of cells with better binocular tuning is due to the improvement of orientation tuning in monocular responses as well as improved alignment of orientation preferences between the two eyes.


Development and matching of binocular orientation preference in mouse V1.

Bhaumik B, Shah NP - Front Syst Neurosci (2014)

(A) HWHH histogram for the cells in a 35 × 60 patch from the binocular region in the cortex. The histograms are shown from 500 to 3000 epochs at an interval of 500 epoch. (B) Histograms of preferred orientation difference between the two eyes at (i) 500, (ii) 1500, and (iii) 2500 epochs. In (iv) the histograms in (i)–(iii) are compared with uniform distribution (green line). Uniform distribution is the expected distribution of /ΔOR/ when the left and right receptive fields develop independently. At 500 epochs, /ΔOR/ distribution is almost uniform. There is not much improvement in /ΔOR/ between 1500 and 2500 epochs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109519&req=5

Figure 7: (A) HWHH histogram for the cells in a 35 × 60 patch from the binocular region in the cortex. The histograms are shown from 500 to 3000 epochs at an interval of 500 epoch. (B) Histograms of preferred orientation difference between the two eyes at (i) 500, (ii) 1500, and (iii) 2500 epochs. In (iv) the histograms in (i)–(iii) are compared with uniform distribution (green line). Uniform distribution is the expected distribution of /ΔOR/ when the left and right receptive fields develop independently. At 500 epochs, /ΔOR/ distribution is almost uniform. There is not much improvement in /ΔOR/ between 1500 and 2500 epochs.
Mentions: For binocular RF development prior to the critical period, we use Equation (1) till 500 epochs. We start the iteration with very small (of the order of 10−6) random values of synaptic weights. Due to reaction term, the weights quickly increase and observable responses from cells with orientation tuning start from 500 epochs onward. A significant number (approximately 20%) cells display orientation tuned monocular responses at 500 epochs. But as the receptive field in two eyes develop independently, only 4% cells have both tuned left and right monocular responses with absolute value of /OD/ < 0.8 and maximum spike rate in left and right monocular responses greater than 3 spikes/s (baseline firing rate of cortical cells). Experimentally oriented cells are observed at the start of critical period (Wang et al., 2010). In our simulation we take 500 epochs as the start of the critical period. We develop synaptic weight using Equation (2) from 500 to 3000 epochs. Histogram of HWHH of binocular cells is shown in Figure 7A starting from 500 epochs to 3000 epochs at an interval of 500 epochs. With increase in epochs the number of binocular orientated cells increases from 4% at 500 epochs to 39% at 3000 epochs. The increase in number of cells with better binocular tuning is due to the improvement of orientation tuning in monocular responses as well as improved alignment of orientation preferences between the two eyes.

Bottom Line: At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective.The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells.It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels.

View Article: PubMed Central - PubMed

Affiliation: Electrical Engineering Department, Indian Institute of Technology Delhi New Delhi, India.

ABSTRACT
Eye-specific thalamic inputs converge in the primary visual cortex (V1) and form the basis of binocular vision. For normal binocular perceptions, such as depth and stereopsis, binocularly matched orientation preference between the two eyes is required. A critical period of binocular matching of orientation preference in mice during normal development is reported in literature. Using a reaction diffusion model we present the development of RF and orientation selectivity in mouse V1 and investigate the binocular orientation preference matching during the critical period. At the onset of the critical period the preferred orientations of the modeled cells are mostly mismatched in the two eyes and the mismatch decreases and reaches levels reported in juvenile mouse by the end of the critical period. At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective. In literature around 40% cortical cells are reported as orientation selective in mouse V1. The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells. The absence of near neighbor interaction among cortical cells during the development of thalamo-cortical wiring causes a salt and pepper organization in the orientation preference map in mice. It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels.

No MeSH data available.


Related in: MedlinePlus