Brain Motor & Sensory Areas

The premotor cortex, not individual muscles, controls complex movements involving multiple muscles.
Example: Grabbing a bravot requires coordinating arm, hand, and finger movements.
Learned, repetitious, or patterned motor skills are stored in the premotor cortex.
This area is responsible for conscious motor control.
The primary motor cortex stores individual muscle activity, while the premotor cortex stores learned motor behaviors.
Learning piano involves storing individual elements of the skill.
Stroke in the premotor cortex (area 6) can erase years of motor memory, requiring relearning of skills.
Physical therapy helps stroke patients relearn motor skills like walking, which may have been forgotten due to damage in this area.
Walking is an automatic motor behavior, stored in the premotor cortex.
The brain has significant capacity for storing motor information; forgetting skills sometimes occurs due to lack of practice.

Broca's area translates thoughts into speech.
It coordinates muscles involved in speech, including lips, tongue, and swallowing.
Damage to Broca's area results in non-fluent speech, sometimes resembling stuttering.
Stuttering caused by damage cannot be corrected using speech therapy.

The frontal lobe is largely responsible for intellect, thinking power, and behavior.

Behind the frontal lobe lie the parietal, temporal, and occipital lobes, which are responsible for sensations.
Sensations include touch (primary somatosensory), vision, auditory, gustatory (taste), and olfactory (smell).
Primary sensory areas receive initial sensory input.
Sensory information is sent to association areas for interpretation and memory recall.
Example: Identifying a remote in the dark relies on tactile memory stored in the somatosensory association area.
New objects are memorized through touch and feeling, creating new memories in the association area.
The postcentral gyrus receives information from skin, joints, and muscles.
Joint receptors, called proprioceptors, provide information about body position.
Proprioceptors are crucial for spatial awareness.
Loss of proprioceptors results in severe spatial disorientation and inability to control body movements.
The postcentral gyrus is responsible for spatial discrimination and identifying the body region being stimulated.
Stimulating the postcentral gyrus electrically can evoke sensations in specific body parts.

The sensory homunculus is a representation of the human body based on the amount of brain area devoted to sensory perception in each part.
Areas with high sensitivity, such as hands, lips, and tongue, are disproportionately large in the homunculus.
Fingers have high brain allocation for sensation, necessary for tactile exploration in the dark.
The face has numerous sensory receptors to avoid injury.
The back of the neck has fewer receptors compared to the face.
The motor homunculus is famous and depicts the amount of motor cortex devoted to different body parts.
Damage to specific areas results in loss of sensation in corresponding body parts.

Animals have different sensory representations based on their needs and behaviors.
Rabbits have a lot of brain material devoted to the head (whiskers) because they move head-first.
Smell (olfactory) is the oldest part of the brain.
Animals with a strong sense of smell, like rats, have larger areas devoted to olfaction (paleocortex).
Vision is processed in the occipital cortex.
Tarsiers, which are nocturnal, have good eyesight and sense of smell.
Tarsiers have large eyes because they are nocturnal.
Babies are cute because of their big eyes, that is why Disney characters have big eyes.

After initial sensory processing, information is sent to association areas for memory storage.
The somatosensory association area stores tactile memories.
The visual association area stores visual memories.
The auditory association area stores auditory memories.
Damage to visual area 17 can cause blindness.
Damage to area 19 can cause inability to recognize faces.

Sensory information reaches the brain via three neurons.
The third neuron goes from the thalamus to the sensory cortex, determining the location of the sensation.
Switching the final neuron connections could cause sensations to be misinterpreted.
Stimulation of the thumb area can cause the forehead to hurt if there are anomalous neurons.
Proximity of genital and foot areas in the sensory cortex can explain why foot massages might cause orgasm.

Anatomy gives clues about function.
The integumentary system and protein synthesis will be covered on the online exam, which will be available from noon tomorrow until Saturday noon.