مركز علوم اعصاب و رفتار رايان

عنوان و چکیده ی سخنرانیهای پروفسور بوژاکی در سمپوزیوم و کارگاه ها بدین شرح است

عنوان و چکیده ی سخنرانی پروفسور بوژاکی در سمپوزیم و روز اول کارگاه

Emergence and mechanisms of cognition

Gyorgy Buzsaki

The Neuroscience Institute, New York University, NY, NY

The fundamental goal of the brain is to predict the future. More complex brains evolved

multiple hierarchical loops between their outputs and inputs to make prediction more

reliable in more complex environments and at longer time scales. With extensive training

these prediction mechanisms have become ‘internalized’. At the center of this model are

self-propagating loops of neuronal coalitions connected by modifiable synapses that can be

propelled forward without external cues. The implication of this conjecture is that brain

networks are endowed with internal mechanisms that can generate a perpetually changing

neuronal activity even in the absence of environmental inputs. I will discuss examples and

mechanisms of this framework

عنوان و چکیده ی سخنرانی پروفسور بوژاکی در روز دوم کارگاه

Why do we need so many neurons

György Buzsáki

The Neuroscience Institute, New York University, NY, NY

Performance in both the cognitive and motor domains, including sensory perception, time and

space perception, decision-making, short-term memory and motor control, obeys the Weber

(log-scale) law. What neuronal mechanisms can support such a wide dynamic range yet in a

well-controlled manner? I will demonstrate that skewed (typically lognormal) distributions are

fundamental to both structural and functional brain organization, including synaptic weights,

firing rates, bursting, population cooperativity, microscopic and macroscopic connectivity, axon

diameter and many derived measures such as place field number, size, information per spike,

etc. In all brain states, a small minority of neurons and connections may be responsible for

"good enough" brain performance. This "backbone", consisting of the fast-firing minority of

neurons in a postulated strongly connected network provides the brain’s "best guess" for "good

enough" performance but deployment of the weakly active majority is needed for precision

performance. The two ends of a continuous log-distribution of physiological parameters may

also explain the perceptual contiguity between "similar" and "different". A minority of strongly

intercorrected neurons may generalize across situations and afford the brain the capacity to

regard no situation as completely unknown. In contrast, the mobilization of the reservoir

majority of weaklt active neurons is needed to reliably distinguish one situation from another. I

will illustrate these speculative ideas with concrete examples