Population Codingの 最近の話題から

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1 Population Codingの 最近の話題から
2018/12/3 Population Codingの 最近の話題から 銅谷賢治 ATR 人間情報科学研究所 科学技術振興事業団 CREST

2 あらすじ 古典的population coding仮説 Population vector 確率的population coding仮説
Bayes/最尤推定 不確定性の表現 複数入力の統合

3 Population Vectors (Georgopoulos)
１次運動野ニューロンの運動方向選択性 cosine tuning fi(m) = bi + ai cos( qm-qi) preferred direction qi は一様に分布 Population vector v(m) = Si fi(m) vi simplicity and robustness.

4 Probabilistic Population Codes (Zemel, Dayan, Pouget 1998)
Encoding: underlying quantity x noisy response: P[r|x] Decoding Bayesian: P[x|r]  P[r|x] P[x] Standard Poisson model encode single value of x P[ri|x] = e-fi(x) (fi(x))ri/ri! P[x|r] = P[x] Pi e-fi(x) (fi(x))ri/ri!

5 Extended Poisson Model
Encode the probability distribution P[x|w] uncertainty, multiple values <ri> = x P[x|w] fi(x) dx Decoding for histogram representation <ri> = Sj fj fij logP[{fj}|{ri}] = K + logP[{fj}] + Si ri log[Sj fj fij]

6 Roles of the Cerebral Cortex
Representations for good generalization modality, invariance, resolution,... task oriented context and working memory Combining multiple outputs reasons for for poplulation coding?

7 Population Coding (Deneve et al., 2001)
Function approximation and Cue Integration

8 おわりに 情報の表現から処理へ Poisson的な発火の積極的な意味付けは？