[Comp-neuro] Re: Comp-neuro Digest, Vol 32, Issue 34
Osame Kinouchi Filho
osame at ffclrp.usp.br
Mon Aug 18 14:51:39 CEST 2008
I'd hope we
can retain some balance and not go too far down either one of these extremes. If you read James, he sounds much more 'modern' than either Freud or Skinner.
Todd, perhaps this (unpublished paper) could be of your interest (see section III about the James Machine):
I am rewriting the paper, with the recent (confirming) evidence from the relatioship between endocannabinoids and unlearning. By the way, there is a misprint along the text (DB1 instead od CB1 receptors). Our justification for using a Hopfield-like model could also be of interest to the present discussion.
Dreams, endocannabinoids and itinerant dynamics in neural networks: reelaborating
the Crick-Mitchison unlearning hypothesis
Departamento de F´ýsica e Matem´atica, Faculdade de Filosofia,
Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo,
Av. dos Bandeirantes 3900, 14040-901, Ribeirao Preto, SP, Brazil.
Renato R. Kinouchi
Departamento de Filosofia e Metodologia das Ciencias
Centro de Educa¸cao e Ciencias Humanas - Universidade Federal de Sao Carlos
Via Washington Luiz, Km 235, CEP 13565-905, Sao Carlos, SP, Brasil.
In this work we reevaluate and elaborate Crick-Mitchisons proposal that REM-sleep corresponds to a self-organized process for unlearning attractors in neural networks. This reformulation is made at the face of recent findings concerning the intense activation of the amygdalar complex during REM-sleep, the role of endocannabinoids in synaptic weakening and neural network models with itinerant associative dynamics. We distinguish between a neurological REM-sleep function and a related evolutionary/behavioral dreaming function. At the neurological level, we propose that
REM-sleep regulates excessive plasticity and weakens over stable brain activation patterns, specially in the amygdala, hippocampus and motor systems. At the behavioral level, we propose that dream narrative evolved as exploratory behavior made in a virtual environment promoting emotional
(un)learning, that is, habituation of emotional responses, anxiety and fear. As exploratory behavior, dreaming activates the locomotor areas (basal ganglia, cerebellum), hippocampal spatial memory and amygdalar anxiety/fear responses. These systems present a high density of cannabinoid receptors related to synaptic weakening (unlearning) processes. At variance with the memory consolidation hypothesis, we predict that: 1) REM-sleep excess impairs memory consolidation; 2) high
levels of synaptic weakening agents (endocannabinoids) should be found in amygdala, hippocampus, motor system and other areas activated by REM-sleep; 3) dream amnesia is due to endocannabinoids memory consolidation impairment; 4) nightmares and enhanced REM-sleep after trauma are
brain tentatives of weakening emotional response, not instances of memory consolidation. Our computational
model also predicts that the replay of cells ensembles is done at an increasing faster pace along REM-sleep.
Prof. Dr. Osame Kinouchi
Departamento de Física e Matemática
Faculdade de Filosofia, Ciências e Letras
Av. Bandeirantes 3900, CEP 14040-901
Universidade de São Paulo
Fone +55 16 3602-3779
Sent via the WebMail system at srv1.ffclrp.usp.br
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