Predictive coding posits the existence of separate “prediction” units (P) and prediction error units (PE) within each cortical column, the basic cortical computational module. There are both intrinsic (within the cortical column) and extrinsic (between columns) connections between P and PE units.Prediction and Prediction Error signals travel to and from specific layers.
Large PEs lead to updating of predictions, which are then sent forward as input to higher cortical areas (via superficial layers, L2/3), as well as backward to update predictions in lower areas (via deep layers, L5/6). In this scheme, the excitatory feedback from higher to lower selection function of the basal ganglia is not limited to action selection or reinforcement learning. Given that the basal ganglia receive cortical, limbic, and brainstem inputs and thus have access to motivational,affective,cognitive,and motor information, they may form the final common pathway where information from a wide variety of sources is integrated and then guide selection among cortical representations, actions and goals. I
Functional differences then arise from differences in the input sources and output targets. For example, outcome predictions in dorsolateral stria-tum will be derived from inputs from sensorimotor areas and will lead to action selection, whereas nucleus accumbens, with inputs from the amygdala and VTA, will report reward PEs in a rein-forcement learning task and allow motivational aspects to guide behavior. Hippocampal and prefrontal glutamatergic inputs to the ventral striatum may provide the top-down context information or predictions to modulate neural activity.Signed PEs
https://clinicalgate.com/wp-content/uploads/2015/06/f32-04-9781437702941.jpg Neurons & Layers
http://rstb.royalsocietypublishing.org/content/royptb/371/1708/20160007/F2.large.jpg Prediction Flow
Specifically, valid prior expectations allow for selection of the proper hypotheses (i.e., activating relevant P units) in advance of stimulation, facilitation of perception (Bar, 2004)
CORTICAL PREDICTION ERRORS: LAYERS AND COLUMNS
—- deviate - attracter states https://en.m.wikipedia.org/wiki/Attractor
This paper talks about the body model in layer 4 used to generate predictions. The Body Model Theory of Somatosensory Cortex
"Sensory Gating" ... "Most importantly, is sensory gating under top-down or bottom-up control?". In the Predictive Coding Model, The sensory gating would is the model being pushed down to the senses.
Cortical modulation of sensory flow during active touch in the rat whisker system with a lay person explanation here: Sensory Perception Is Not a One-Way Street
2018.08.26 draft jch
2018.08.26 draft jch