Distributed Representations Meeting, 15 March 2012 Irina Simanova

Materials and methods 7 epileptic patients, 16 sessions Sites: hyppocampus, amygdala, enthorinal cortex, parahippocampal cotrex Microwire electrodes: 8 recording channels and the reference objects (M = 16, SD = 3.1) presented, for each object: 3 pictures, a spoken name, a written name; 6 times each Firing units detected; also addressed if the firing was preferred to pictures (visual invariance) Out of 750 units 79 had a significant response to at least one stimulus

A neuron in the left anterior hippocampus

A neuron in the enthorinal cortex

A neuron in the amygdala

Response invariance Visual invariance: ROC analysis, p<0.01 Triple invariance: visual invariance + significant responses to spoken or visual names N responses to the individual / total number of pictures of this individual (3). N responses to the other pictures/ total number of other pictures. Amplitude thresholds:

Visual invariance

Triple invariance

Discussions:

Modality-independent decoding of conceptual information (fMRI study) (Simanova et al., submitted)

Searchlight SVM, generalization across the four modalities, group-level statistical results

Multimodal integration = conceptual representation ?