Essentials: How Your Brain Functions & Interprets the World | Dr. David Berson

In this lecture, Dr. David Berson, a neuroscientist, outlines the fundamental principles by which the human brain functions and interprets the world. He begins by examining the basic unit of the nervous system—the neuron—and describes how its structure supports information processing. Neurons possess dendrites to receive inputs, a cell body for integration, and a long axon for transmitting signals. At the core of neural communication are action potentials, rapid electrical impulses generated by the coordinated opening and closing of voltage-gated ion channels. Berson explains how sodium and potassium fluxes across the neuronal membrane produce the characteristic spike in voltage, enabling information transfer over long distances. Next, Berson addresses synaptic transmission, the chemical interface between neurons. Neurotransmitters released from the presynaptic terminal bind to receptors on the postsynaptic neuron, modulating its excitability. He highlights the diversity of neurotransmitters—excitatory, inhibitory, and modulatory—and their roles in shaping brain function. Plasticity, the capacity of synapses to strengthen or weaken over time, underlies learning and memory. Berson provides examples of long-term potentiation (LTP) and long-term depression (LTD), illustrating how experience can rewire neural circuits. Moving from single neurons to networks, Berson discusses how groups of interconnected neurons form functional assemblies dedicated to specific tasks, such as sensory perception or motor control. He describes receptive fields in sensory neurons—regions of the sensory surface to which a neuron responds—and shows how these fields become more complex at successive processing stages. For instance, visual receptors detect light intensity, while cortical neurons integrate this input to recognize shapes and movement. A central theme is the brain’s ability to construct an internal model of the external world. Berson examines how sensory ambiguities—like optical illusions—reveal the brain’s reliance on prior knowledge and statistical inference. He outlines predictive coding theory, proposing that higher brain regions send expectations down to sensory areas, comparing predictions to incoming data and signaling mismatches. Towards the conclusion, Berson emphasizes the brain’s remarkable energy efficiency: despite constituting just 2% of body weight, it consumes roughly 20% of metabolic energy. He attributes this to sparse coding strategies and the balance of excitatory and inhibitory activity that minimizes redundant firing. Finally, he reflects on how understanding these mechanisms not only informs basic science but also guides interventions for neurological disorders. By dissecting the cellular and network principles of brain function, the lecture sheds light on how our brains perceive, learn, and adapt.