Functional Systems of the Brain

The Central Nervous System and Functional Systems

• The amygdala is linked to social behavior and emotional expression, while the hippocampus is vital for memory, and the basal ganglia manage fine motor control.
• Major functional systems in the central nervous system involve distinct brain regions that process information across different stages.
• Sensory modalities (touch, vision, hearing, taste, smell) and associated actions have dedicated circuits, and the thalamus serves as a critical relay for sensory information to the primary sensory cortices.

Information Processing in Neural Circuits

• Functional systems consist of serially organized components, often referred to as relays; however, they transform information at each stage, modifying inputs before passing them on.
• The output of neural circuits is influenced by the summation of inputs received from numerous presynaptic neurons, with varying amplification or attenuation depending on states like arousal.
• Neurons are categorized into two functional types: principal (projection) neurons, which connect different system components, and local interneurons that integrate local processing.

Role of the Cerebral Cortex

• The cerebral cortex, a thin outer layer of the cerebral hemispheres, plays a crucial role in cognitive functions such as planning and executing daily actions.
• Human cerebral cortex is highly evolved, featuring convoluted structures formed by gyri and sulci, which may have developed to accommodate increased neuronal density.
• The cortex is consistently about 2 to 4 mm thick across species, but size and number of neurons vary, with humans possessing a significantly larger surface area.

Divisions of the Cerebral Cortex

• The cortex is anatomically divided into four lobes: frontal, parietal, temporal, and occipital, each hosting distinct functional regions.
• Specific areas within the temporal lobe are responsible for auditory processing, visual recognition, and memory functions.
• Brodmann's cytoarchitectonic regions offer a classical analysis of the cortex, noting variations in layers across motor and sensory functions.

Neuronal Cell Types in the Cortex

• The cortical neurons exhibit various shapes and sizes, primarily classifiable as projection neurons (pyramidal shape) and local interneurons.
• Projection neurons predominantly use glutamate as a neurotransmitter, while local interneurons, constituting 20-25% of neocortex neurons, generally utilize GABA and can be classified into subtypes like basket and chandelier cells based on their connections.

Integration of Motor Information

• Motor information is modulated by sensory feedback and influences from related brain regions, including the cerebellum and basal ganglia, which are essential for coordinated movements.
• The cerebellum affects posture and movement by integrating sensory information and facilitating connections to the motor cortex through the thalamus.

Sensory and Motor Processing Pathways

• Sensory and motor systems consist of parallel and hierarchical pathways, processing information through a series of identifiable neuron groups for increasingly complex tasks.
• Sensations such as touch and pain are conveyed by distinct pathways that merge at various midbrain and cortical levels.
• Cognitive science examines how the brain creates internal representations based on sensory input, highlighting the abstraction of sensory experience rather than direct replication.

Conceptual Framework in Neuroscience

• The complexity of sensory experience arises from the brain’s capacity to analyze and integrate various features of stimuli, challenging common perceptions of perception as direct reflection of the external world.
• Current neural and cognitive sciences focus on unresolved questions regarding information integration (the binding problem) and the emergence of conscious experience from selective attention.

This quiz explores the major functional systems within the central nervous system, focusing on key brain regions such as the amygdala, hippocampus, and basal ganglia. Learn about how these areas influence social behavior, memory, and motor control. Test your knowledge on the principles governing organization across various modalities of sensation and action.