Neuro Week 4 - Frontal Lobe

Size of Frontal Lobe

biggest lobe, 1/3 of the hemisphere

Functions

• motor: movement, skilled and voluntary movement

• cognitive/executive functions: abstract thinking, problem solving, planning, organizing, reasoning, decision making

• language functions: speech and language production

• emotional functions: emotional regulation and appropriate responses

Structures of Frontal Lobe and their Brodmann areas

• primary motor cortex or precentral gyrus: BA 4

  • homunculus

• premotor cortex (association/secondary cortex): BA6

• prefrontal cortex

• Brocas area: BA 44,45

Primary motor cortex or Precentral gyrus (locay + func)

• just in front of the central sulcus

• commands motor movement, initiates and controls voluntary and skilled movement of skeletal muscles contralaterally

Homunculus

• divides motor cortex into areas that control different body parts

• amount of cortical space given on map to body part is based off of how precise and detailed movements of that body part is (not based on size of body part)

• more diverse and precise movements get a larger amount of motor cortex

The premotor cortex (association/secondary cortex)

• in front of the primary motor cortex

• plans and initiates complex skills and movements

  • movements that are practiced and become accurate, efficient, and consistent

The prefrontal cortex

Critical for executive functioning:

• related to personality, cognitive functions (reasoning, planning, decision making), moderating correct social behavior and speech

Brocas Area

• left frontal lobe

• critical for SPOKEN language production

• matches the sounds of words to specific throat, tongue, and mouth movements needed to articulate speech

• motor speech center: plans and organizes speech movements

Associated symptoms

• Contralateral paralysis

• Impaired cognition (higher level thinking)

• Frontal lobe syndrome (changed personality) - inappropriate social behavior

• Broca’s aphasia - impaired expressive language

• Apraxia of speech - motor speech disorder

Apraxia

• NOT caused by paralysis of muscles, incoordination, sensory deficit, or lack of comprehension

• Individual understands the skilled motor act asked of them and can physically do the same movement in a different context, but when it is being asked of them on command they cannot do it

Apraxia of Speech

• difficulty with speech motor programming

• an individual knows what they want to say and their muscles can move but their brain has difficulty programming the sequence of movements need to produce the speech sounds

• Inconsistent error patterns - individuals might say the same word incorrectly in different ways each time

• more errors will occur with more complex words

• individuals are better with automatic speech - things that come naturally like countins 1,2,3 or greeting smo

• worse w volitional speech - intentionally producing speech

• often co-occurs with Broca’s aphasia