Descriptive Psychopathology: The Signs and Symptoms of ...

68 Section 1: Present, past, and futureBrainstem and midbrain structures innervate the muscles of the face, mouthand throat. These motor structures can act independently of cortical control andtheir release is seen in emotional incontinence and pathological crying, and ictaland post-ictal chewing movements.The cerebral cortical areas involved in basic movement include the primarymotor area (Broadman 4), the supplementary motor area (SMA, Broadman 6),the primary sensory cortex (Broadman 3, 1, and 2), and the posterior parietalcortex (Broadman 5 and 7). Sensory and motor cortical–cortical fibers facilitatenormal movement in addition to integration through the thalamus.The prefrontal cortex, primary motor cortex, and the supplementary motorcortex use sensory information in their generation of skilled movements.A disconnection between motor structures and adequate sensory information(e.g. from a thalamic lesion or parietal lobe disease) can elicit catatonia. 75 Theprefrontal cortex provides executive control of movement, planning, initiatingand monitoring, self-correcting movements, and stopping movements when tasksare completed. Psychopathology is commonly associated with disease affectingthe prefrontal cortex and associated parallel circuits.The above structures move the body at will. There are many more movements,however, than there are pyramidal cell motor neurons, so movement relies onprocedural memory (in essence, movement programs) that recruit the differentcombinations of pyramidal neurons needed for each task.Once the movement program is initiated, the muscles of the upper limbs andshoulders are controlled primarily by a contralateral descending pathway, whilethe muscles of the trunk and legs are controlled by a second, mostly uncrossedbut bilaterally integrated pathway, explaining why in stroke leg function oftenrecovers better than that of the hand. The control of the arm and hand are alsoindependent, explaining why many stroke patients can adequately reach for butpoorly grasp or manipulate objects. 76The basal ganglia and cerebellum modulate movement. The basal ganglia andcerebellum provide input to the frontal cortices through the thalamus. They areessential in the learning of new motor programs.The basal ganglia are an integral part of frontal lobe circuitry. They also haveafferent and efferent connections to the limbic system and release motor programs forflight/fight. The basal ganglia fine-tune movement and provide procedural memoryprograms of learned motor sequences (e.g. riding a bike). They are involved in selfmonitoringof conversational speech and participate in facial expression duringconversation and spontaneous emotion. 77 They subserve attention, working memoryand new learning, and sensory-motor and visual-motor sequencing. Disease of thebasal ganglia typically leads to problems with motor function, cognition, and mood. 78