Figure 5.

Activity-Dependent Development

(A) Left: Orientation selectivity map in the visual cortex of a ferret (Kaschube et al., 2010). The colors represent the orientations in the visual field to which each point in the cortex is most responsive; the white arrows in the inset highlight pinwheels, where all orientations are represented around a point. The map wavelength is about 1 mm. Right: Average pinwheel density from several animals is close to π.

(B) Left: Maps formed in models with and without long-range connections: only the former produce maps resembling those seen experimentally (cf A). Right: Pinwheel density for the simulated maps is remarkably similar to that seen experimentally (Kaschube et al., 2010). (A and B) reproduced with permission from Kaschube et al. (2010).

(C) Left: Simulated orientation maps with overlaid pinwheels (black dots) and ocular dominance column borders (black lines) for a normally reared animal from the model of Cloherty et al. (2016). Right: Predicted map for an animal seeing horizontal contours in one eye and vertical contours in the other during development. Reproduced from Cloherty et al. (2016).

(D) Sample of oriented receptive fields produced by applying independent components analysis to natural scenes. Each gray square represents one neuron's receptive field, and the weights in that receptive field are represented by the gray scale with most weights being zero. Reproduced from Hyvärinen et al. (2009).

(E) Dependence of change in synaptic strength with time Δt between pre- and post-synaptic spikes for STDP and BTDP.

(F) Examples of oriented receptive fields produced by a model using an STDP learning rule. Gray scale is similar to (D). Reproduced with permission from Clopath et al. (2010).

(G) (i) Retinal waves observed experimentally in ferrets at three different time points; each panel corresponds to an approximately 2 by 2-mm patch of retina. (ii) Simulated retinal waves from the model of Butts et al. (1999). (iii) Simulated retinal waves from the model of Godfrey and Swindale (2007). (iv) Simulated retinal waves from the model of Albert et al. (2008). Reproduced from Albert et al. (2008).