Thoughts on Reality An insubstantial pageant The one thing we can be reasonably sure of is that what we see has nothing to do with reality. Physics tells us as much as that; that there are no things and there is no colour green. Visual information is delivered to the retina by photons fluctuating at varying frequencies. The photons are either reflected from or produced by ‘objects’, which can in their turn be understood as quantum particles held together by the charges of the electromagnetic Read more […]
Archive for the ‘Neuroscience and perception’ Category
Brain’s taste secrets uncovered Based on BBC Health and Nature www.nature.com/ Summary and review of the above article A study at Columbia University has demonstrated the specialised nature of neurons related to taste. The tongue has about 8,000 taste buds. Each bud is able to respond to the full range of salty, bitter, sour, sweet and umami. However, these versatile taste buds in fact contain specialised cells which respond to only one of these tastes. It was found that stimuli acting Read more […]
The field of affective neuroscience, initiated by Panksepp and Ledoux, embraces the concept that emotional processes are based on brain structures that operate in parallel with cognitive processes, and can thus influence behaviour independently of cognition.
In this conference Donald Hoffman discussed why qualia are more relevant than Dennett had tried to argue in the 1990s. Another highlight was the exchange between Hameroff and Tegmark, where Tegmark took a surprisingly casual view of his much vaunted 2000 Paper.
Studies of neural activity in response to both complex visual scenes and also tastes revealed the neural code for a continuous axis of pleasant to unpleasant emotional values (valence). The medial and lateral orbitofrontal cortices (OFC) supports a valence code that is independent of the sensory origin of signals. This allows the attractive or aversive qualities of signals to be quantified regardless of the nature or modality of the stimuli.
The orbitofrontal cortex and ventral striatum encode expected outcomes during decision taking. Activity in these brain regions also reflects the perception of missed opportunities. Neural signals related to regret at missed opportunities are encoded here.
Even at the very early stage of the retina, an important division arises between two parallel visual streams, the dorsal stream and the ventral stream. The dorsal stream projects to the parietal cortex, and is responsible for movements in relation to objects, many of them of a routine or reflex nature. It is also seen as an answer to the ‘where is it?’ location question. The processing of the dorsal is unconscious, and is faster than the consciousness-related processing of the ventral stream.
Frigato identifies two areas of the cingulate brain region, the anterior cingulate and the precuneus-posterior cingulate as necessary for consciousness, while eight other areas, the medial-superior temporal lobe, the anterior and posterior insulas, the superior and inferior parietal, the inferior frontal and two motor cortices are involved at various stages in conscious processing. Frigato says that his own research concurs with the idea of points of convergence in the brain where both a perception and the memories and emotions related to that perception can be held in the same neural structure.
Consciousness and the Brain, Stanislas Dehaene (2014) Summary and review of the above book INTRODUCTION: On the basis of the brain research of recent years, Dehaene describes both the extent and limitations of unconscious processing. Such processing can extend to sophisticated levels of cortical processing, such as the meaning of words. However, unconscious signals are transient and decay rapidly in the brain, while conscious signals can persist long after the original stimuli. Decision taking Read more […]
Ed. George R. Mangun. Oxford University Press (2012) Summary and review of the above book INTRODUCTION: Voluntary attention is shown to be involved with slower and more deliberative processing, as opposed to the quick reaction of involuntary attention. Voluntary attention involves the frontal brain regions dealing with both emotional/evaluative and planning/working memory processing; these are some of the areas most closely correlated to conscious experience. They are thought to influence Read more […]