Striatum

THE STRIATUM: EMOTION, PLEASURE, BODY LANGUAGE, AND SCHIZOPHRENIA The corpus striatum (caudate and putamen) and limbic striatum (olfactory tubercle, nucleus accumbens, stria innominata) are buried deep within the frontal lobe, with the head of the caudate arising from near the orbital floor and then ascending deep alongside the inner medial and lateral walls The striatal nuclei are thus intimately associated with the orbital, medial and lateral frontal lobes, as well as the amygdala with which they merge in the temporal lobe. It is through these frontal-striatal-amygdala pathways that emotional states come to translated into complex motor acts and expressed through body language.

-Mediates facial expression and gesture -Produces ballistic movements: hitting, kicking, running and biting
 * Primary Functions:**

Intimately associated with the orbital, medial and lateral frontal lobes, as well as the amygdala with which they merge in the temporal lobe. It is through these frontal-striatal-amygdala pathways that emotional states come to translated into complex motor acts and expressed through body language.
 * Connections:**

Electrical Stimulation: -Neuron destruction disrupts the capacity to experience pleasure such as by opiates and cocaine. -Lesions to the corpus striatum and lenticular nucleus (putamen and globus pallidus) can attenuate one's capacity to experience pleasure or motorically express their emotions via the musculature; e.g. the face & body becomes frozen -Surgical destruction of or chemical lesions to the anterior corpus striatum and surrounding tissue can produce catatonic or "frozen" states, including prolonged posturing where the subjects will remain unmoving for hours, days, and even weeks at a time
 * Injury/Damage:**

-Similar paralytic, petrified disturbances can be induced with dopamine depletion. Indeed, a major function of striatal DA is inhibition, and DA depletion can trigger striatal as well as limbic hyperactivation. IThe patient may become catatonic may demonstrate signs of Parkinson's disease. -Excessive Dopamine, and reduced striatal activity can disrupt all aspects of motor, cognitive and emotional functioning, with some patients developing an acute schizophrenic psychosis. In addition to reduced activity and metabolism, limbic striatal structures are reduced in size whereas the corpus striatum has been found to be increased in size in schizophrenics vs normal controls especially in the left hemisphere. Moreover, as the lateral frontal neocortex is also innervated by striatal as well as DA fibers, reduced DA levels can also negatively impact the lateral frontal lobes as well as the striatum.
 * Role of dopamine**

If the frontal lobes become abnormal secondary to striatal/DA disturbances, frontal symptoms will be evoked. Hence, striatal dysfunction is also associated with depression, apathy, obsessive compulsive disorders, "schizophrenia," as well as mania, depending on the nature, degree, extent, and laterality of destruction.
 * Secondary Frontal lobe symptoms**

Right caudate - more likely to result in a manic-like psychosis --similar to right frontal lobe injuries. Left or bilateral caudate injuries - associated with apathetic states, decreased spontaneous activity, slowed and delayed dysarthric and emotionally flat speech, with some patients responding to questions only after a 20-30 second delay.

Since the head of the striatum descends ventrally between the lateral and medial walls, injuries to this part of the brain, including DA abnormalities, also disrupts these adjoining tissues. If the right or left lateral walls are injured, patients are likely to appear manic or apathetic, depressed, irritable, and schizophrenic. However, if the medial walls of the frontal lobes are injured, cognitive, motivational, and motor functioning will become profoundly abnormal, and the patient may become completely catatonic.

Since humans possess basically the same striatum and limbic system, when happy, sad, angry, and so on, the facial and body musculature assumes the same readily identifiable emotional postures and expression regardless of culture or racial orgins. The striatum is capable of considerable flexibility in motor-emotional expression, and is exceedingly responsive to the internal motivational and emotional state. Through its extensive interconnections with the limbic system and the mesolimbic dopamine (DA) system the striatum is able to perceive emotional stimuli and can "experience" pleasure. Striatal neurons selectively respond to motivationally significant stimuli that are rewarding or punishing (Rolls and Williams 1987; Schneider and Lidsky 1981) and can generate feelings of pleasure in reaction to amphetamine, cocaine and opiates
 * Notes:**