Somatosensory Processing

• Neural signaling gives rise to mental activity, which includes perception, planned action, and thought.
• The study of individual neurons' activity, combined with cognitive psychology and advanced imaging, has led to a greater understanding of the biological basis of behavior.

Somatosensory Processing

• It is a model for understanding how the nervous system generates perception, planned action, and cognition.
• Neural activity from individual neurons and populations contributes to complex cognitive processes, including perception and decision-making.
• It involves the transformation of stimuli into neural signals.
• These signals relay through the dorsal column-medial lemniscal pathway to the cortical representation in the somatosensory cortex.
• The role of the primary somatosensory cortex (S-I) is differentiated from the secondary somatosensory cortex (S-II) and posterior parietal cortex.
• The S-I is important in sensory integration and perception of personal and extrapersonal space.

Topographical Mapping

• It is significant in the primary somatosensory cortex (S-I).
• Brodmann areas 3a, 3b, 1, and 2 have functional importance.
• Neuronal receptive fields contribute to sensory perception.
• Overlapping receptive fields enhance the representation of stimuli in the somatosensory cortex.
• The somatosensory cortex has columnar organization, which is a fundamental principle of cortical processing.
• The functional specialization of association cortices includes the prefrontal cortex, parietal-temporal-occipital cortex, and limbic system.
• These areas are important in higher-order cognition and behavior.

Plasticity

• Somatosensory representations are plastic, and experience and injury can reshape cortical maps.
• This contributes to phenomena like phantom limb syndrome.

Cerebral Hemispheres

• Functional asymmetry uses evidence from split-brain patients to illustrate the lateralization of cognitive functions.
• These cognitive functions include language and spatial reasoning.

Orderly Representation of Personal Space

• The brain has an orderly representation of personal space, illustrated by structures such as the central sulcus, S-I, S-II, and postcentral gyrus.
• The sensory homunculus represents the orderly mapping of the body onto the somatosensory cortex.
• Sensory processes in the DRG travel to the cuneate nucleus of the medulla.
• Relays cross the midline from the medulla to the ventral posterior thalamic nucleus.
• Signals travel from the thalamus to the primary somatosensory cortex (S-I).
• Damage to the somatosensory cortex can cause proprioception deficits.
• Sensory processes in the DRG travel to the cuneate nucleus of medulla.
• Relays cross midline from medulla to ventral posterior thalamic nucleus.
• From thalamus to primary somatosensory cortex (S-I)

Cortical Representation

• The somatosensory system has a cortical representation.
• The cortex has a map for each sub-modality of sensation.
• Information processed in the primary somatosensory cortex (S-I) projects to the secondary somatosensory cortex (S-II) and posterior parietal cortex.
• Each central neuron has a specific receptive field.
• Internal representation of space can be studied at the cellular level.
• Neuronal processing involves divergence through relays.
• Touch and proprioception are key senses processed by this system.
• Inputs into the somatosensory cortex are organized into columns based on sub-modality.
• The representation of space in the cortex can be modified by experience, showing flexibility in the cortex.

Association Areas

• Real and imagined space is represented in the parietal association areas.
• Neglect syndrome can result from damage to these areas.
• Cognitive functions are the result of neuronal activity in association areas of the cortex.
• The two hemispheres are not created equal and have different cognitive capabilities.
• The progression goes from the motor cortex/unimodal sensory cortex to the premotor cortex/higher-order sensory cortex to the prefrontal cortex/parietal-temporal-occipital cortex and then the limbic cortex.