Neuroscience

Associative Conditioning Classical Conditioning Pavlov’s experiment He was interested in digestive systems of dogs. Then he notices that if we show food to dog, they start to salivate. If paired with sound (tuning fork) they start to salivate even if they just hear the sound. He defines two states: Before conditioning During conditioning After conditioning state. Important words are conditioned stimulus, conditioned response. And their oppose (unconditioned). It is important that it is quite consistent. Associate unconditioned stimulus with conditioned stimulus. ...

How are inputs made into motion? We analyze feedback systems in auditory systems in birds. Motivation Birds are very good at producing and reproducing songs by moving their vocal cords complexly (sensory motor learning). Birds and Humans do not have much of a common ancestry (last one was fishes). 71% of the birds, both female and male birds sing, for Zebra finch it is a mating behaviour, so only male sing. ...

First, the brain is organized into functionally specific areas, and second, neurons in different parts of the vertebrate nervous system, indeed in all nervous systems, are quite similar. Small comparison with Computers A gross observation between computer’s transistors and human neurons is that there a big difference of numbers: trillions of transistors vs billions of neurons. 6 orders of magnitude frequency difference. Many many neural types and different types of connections. And the digital vs analog and chemical modes of communication. Parallel processor abilities. Fixed vs plastic architectures But this is comparing with transistors with one higher level object, so this comparison might not be completely fair. And only some brain areas are similar to real neural networks ...

Here we attempt to answer what is memory, how is it stored and retrieved. Memory is a process by which information is: Encoded Stored Retrieved The brain has different types of memories, and certain brain regions are specialized for this task. Ebbinghaus Curves Other experiments destroy parts of the cortex and correlate this with recall. Types of memory TODO see Kendal67-1 figure. Sensory memory iconic memory (remembering images) 150-500 milliseconds Echoic memory (recognizing some sounds) usually retained for 1 to 2 seconds. This memory is filtered by consciousness/attention to be passed to short term working memory. The register capacity of this memory is considered to be quite large. Short-term memory it has an explicit storage of about 7 +- 2 items (so very small). Depending on attention level, it is retained for 2 to 18 seconds. It seems the representation here is often vocal. ...

The synaptic connections that define such circuits are typically made in a dense tangle of dendrites, axons terminals, and glial cell processes that together constitute what is called neuropil. Knee-Jerk Response The knee-jerk reflex (also known as the patellar reflex) is a classic example of a mono-synaptic reflex arc, which involves a direct connection between sensory and motor neurons, as well as inhibitory circuits to regulate movement. ...

Metodi di registrazione informazione Ci stiamo chiedendo in che modo possiamo registrare attività del cervello e quindi cercare di fare decoding delle informazioni presenti Prima parliamo di alcune tecniche non invasive che ci permettono di vedere alcune attività presenti nel cervello. Metodi macroscopici Functional Magnetic Resonance Imaging Un metodo è fMRI. (ci sono cose ) TODO capire come funziona Electro-Encephalo-Gram EEG che prende direttamente dai segnali Ma il drawback di entrambi è che non registrano attività del singolo array. ...

The Potassium Exchange values We use the measurement by Cole and Curthis 40mS/cm squared was their measure of Potassium ions leaving the membrane $$ \Delta Q = Idt = GA \Delta E dt $$The potassium concentration is 0.155 moles per litre. Where $G$ is the conductance per unit area, $A$ the membrane surface, $E$ voltage deflection Remember that the conductance is the reciprocal of the resistance, and $V = IR \implies I = \frac{V}{R} = GV$ ...

What is a neural system? A neural system is an intricately organized network of specialized cells—primarily neurons, along with a variety of supportive glial cells—that processes and transmits information via electrical and chemical signals. In biological organisms, such systems underpin the entire nervous system, coordinating functions that range from basic reflexes to the complex interplay of perception, thought, and behavior. Early studies in neurobiology revealed that even simple neural circuits can generate coordinated responses, while modern neuroscience has shown that vast, hierarchically structured networks (such as the central and peripheral nervous systems) are responsible for the rich tapestry of animal behavior and cognition ...

Synapses are the connections that exist between one neuron and another, so we can think of them as the communication channel between neurons. Gap Junctions Electrical based 🟩 These are also called Gap Junctions These are more direct connections between neurons, allowing excitation ions to pass through quite directly (this is the difference compared to chemically based ones). It’s a circuit more similar to an electronic one because it’s faster. Another characteristic of these kinds of synapses is that they are two-way channels. ...

Some history: Reticular Theory vs Neuron Doctrine The late 19th century witnessed a debate in neuroscience between Camillo Golgi and Santiago Ramón y Cajal, two pioneers whose opposing views shaped our understanding of the nervous system. This debate centered on the structural and functional organization of neurons, culminating in their joint reception of the 1906 Nobel Prize in Physiology or Medicine. Golgi’s Reticular Theory Golgi proposed the Reticular Theory based on his staining techniques (see #Staining methods), which held that: ...