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Mind from brain

  1. 1. MIND FROM BRAIN Select MIND TOPICS from MENU on LEFT Reduce Display ZOOM accordingly 05/08 - 11/20/08 “MIND” IS AN EMERGENT ABSTRACTION OF “SELF” OUT OF CORTICAL NEURONAL CIRCUIT ACTIVITY UTILIZING: - Sensory Inputs, Memory Storage & Recall - Thalamic Gating of inputs to- Cortical Regions: for Sensory Memory, for Emotion (Cingulate) for Basal Ganglial-Motor Control for Cognition (Prefrontal) Open Copyright 2009 D.E. Hillman Brought to you by
  2. 2. MIND VS BRAIN BRAIN MIND B O D Y Hillman The Brain and Body stand as physical elements forming operational components sustaining vertebrate life. Sensory-motor reflexes together with programmed movements, from basal ganglia, represent the bulk of brain operational control over body movement. In mammals advanced development of the cerebral cortex and thalamus has generated an emergent property of the functional brain “THE MIND”. The emanation of the MIND from sensory inputs defines: SELF with MEMORY and EMOTIONS, produces COGNITION forming frameworks of understanding and MAKES DECISONS for initiating motor actions expressing behavior and speech content. Brought to you by
  3. 3. MIND & BRAIN FUNCTIONSTwo principal roles of the Central Nervous System (CNS) are in: 1) operating motor control systems and 2) generation of the MIND. Motor controls are: a) spinal cord and brainstem reflex-control of voluntary muscles producing involuntary reflexes. Reflexes are direct sensory inputs to the spinal cord and brainstem eliciting motor responses in skeletal muscles), b) homeostatic motor control of involuntary muscles and gland secretions via sympathetic and parasympathetic systems, and c) programmed automatic motor control via the basal ganglia and cerebellum acting to produce basic and conditioned motor control of behaviors and speech capability. Besides the control of reflexes, the BRAIN produces an emergent energy state, “THE MIND”, forming self-awareness and yields consciousness. The MIND manages sensory inputs and memories and associates them with “event emotions”. Using memories and emotions, the MIND forms frameworks of understanding expressing the intellect in cognition. Using intellect, the MIND makes decisions for initiating volitional behavior and speech content. While patterned movements are programmed in the action generators, basal ganglia, producing behaviors and speech capability, the MIND makes decisions for selecting and initiating patterns of movement but has limited control over reflexes or the actual movement patterns themselves. Nevertheless, the MIND trains programs, consciously by trial and error testing in order to enhance automatic movement patterns represented by our movement finesse and behavior expressions. Brought to you by
  4. 4. COMPONENTS OF MIND• CONSCIOUSNESS – Awareness of: • Sensory input • Motor responses • MEMORY – Memory Storage – Memory Recall – Memory Association (Thought) – Memory Retention and Forgetting • MIND & VALUES DEFINED IN EMOTION – Survival: Nutrition, Procreation – Self-Esteem - Recognition of Self as based on Pleasure/Displeasure Principles – Reinforcement of values by Culture and “For the Greater Good” of the Species • INITIATION OF BEHAVIOR AND SPEECH – Decision Making for initiating patterns of movement – Decision-Making for speech content • COGNITION – Structural/Functional Framework of Understanding – Determining Consequence of Actions – Perceived Spatial - Temporal Order of Events & Related Structure • PREDICTION (INTUITION) – Imagination – Vision • PERSONALITY and SPEECH (Mind Initiated (volitional) Motor Actions) » D E Hillman 5/1/ 2008 Brought to you by
  5. 5. CNS COMPONENTS The Central Nervous System (CNS) consists of the spinal cord, brainstem, cerebellum, basal ganglia, thalamus and cerebral cortex. The cord and brainstem represent sensory nerve input regions except for olfaction. The cord and brainstem operate reflexes of spinal and cranial nerves. Basal ganglia (BG) are origins of patterned movements that are passed through the thalamus to the cerebral cortex. The thalamus is a timing gate for synchronizing sensory inputs, motor control and cognition to the cerebral cortex. The Cerebral Cortex is the primary source of MIND generating consciousness. Brought to you by
  6. 6. FLOW IN THE FUNCTIONAL MIND The flow of function in the conscious MIND is from sensory inputs or memory storage to emotion centers. Values are placed on incoming sensory inputs and memories by MIND. Emotions are associated with inputs and stored memories and are held in the cingulate gyrus for recall. MIND’s major utilizations of memory is in forming frameworks of understanding (cognition) leading to intellect and in making decisions for motor actions of behaviors and speech content. Brought to you by
  7. 7. THE BASES OF MIND • “MIND” has no comparable descriptive terms. The source of the conscious MIND is from synchronous functioning cortical pyramidal cells integrating sensory input, emotion, motor control and cognition from thalamic relay sources. The collective activity of pyramidal circuits yields a “conscious abstraction of self-awareness and intellect” that is expressed to the world through behaviors and speech. This synchrony is controlled by the thalamus allowing the intelligent MIND to integrate signals between 5 functional domains: 1) inputs to sensory cortices; 2) memory storage and recall; 3) emotion generation; 4) motor decision- making; and 5) cognition, forming a frame-work of understanding. • An understanding of the conscious MIND must include: 1) spinal cord and brainstem sensory-motor reflex organization, 2) thalamic gating of cortical sensory & motor inputs allowing sleep, 3) thalamic-cortical synchronization of sensory-motor data packets producing the awake conscious MIND, 4), emotion generation by amygdala, hippocampus and limbic cortical circuits, 5) basal ganglial patterned-reflexes that are initiated by intelligent decision- making of the conscious MIND and, 6) cognition, forming frameworks of understanding that emerge from the frontal lobe. Brought to you by
  8. 8. UNDERSTANDING THE MIND• The MIND emerges from phased-simultaneity of pyramidal cell inputs across four processing regions of the cerebral cortex that receive inputs by gating of inputs to the thalamus. The linking of temporal activity between the thalamus and cortex synchronizes activity states of cortical neurons across four cortical regions (primary sensory, emotion, cognition and motor) producing an energy state emanating as the MIND. The result is consciousness with the ability to reason and initiate willful behaviors and specify speech content. The essence of the conscious MIND appears as a melding of sensory inputs and memories into a temporal state with emotions and then through recall directs their passage to cognition centers for understanding and motor decision making. • Two temporal indicators of the relationship linking the conscious-MIND and the cognitive-MIND are found in brain-wave signals. The first is the EEG signal that begins each cycle of the frequency from 1 to 40 Hz. The second signal is a longer signal that of high amplitude that appears with a latency from 300 to 600 milliseconds. The latter lasts for a second or more and appears to be the energy state of cognition and decision-making. Brought to you by
  9. 9. MIND & MEMORY • Only conscious and dreaming MINDs contribute to memory storage. The MIND is responsible for assembling memories from: 1) inputs to visual, auditory, olfactory, taste and body contact, 2) sensory responses and consequences arising from motor behavior or speech, and 3) emotions associated with sensory and motor events. Memories are distributed in modality cortices, hippocampus, medial temporal lobe, and cingulate, frontal and parietal cortices. • Sensory MEMORY is distributed, broadly, across regions of the cerebral cortex. Sensory inputs to primary cortices are processed for similarities and differences. Details are processed in associational sensory cortices that surround primary sensory targets. Also primary and associational cortices provide parallel access to memory stores for comparisons with sensory inputs and processing for emotion and cognition. • The MIND can not operate without a functional brain but the brain & body operate without the MIND. As soon as cerebral cortical or thalamic function is lost, the MIND looses consciousness. In addition, the MIND is separable from the BRAIN by the fact that consciousness is turned off during anesthesia, a contusion to the head or states of sleep, yet, the brain keeps on serving homeostatic body functions. Even when MIND-initiating motor- actions are quiescent, testing shows that basic reflex actions still remain. MIND without inputs from sensory systems or memory recall has difficulty to sustain consciousness and lacks ability to make decisions. Memory is the grist for planning and imagination by the MIND. Brought to you by
  10. 10. FORMATION OF MEMORY • MEMORY has two states: the first is unconsolidated memory and the second is consolidated into circuitry. The first state is short term held by the physiological property called LTP (long term potentiation). This short term memory is neuron functional state that activates signaling genes, e.g. c-fos. These early genes trigger phenotypic genes related to protein production during the second state. • The second state occurs during sleep as the memory-consolidating phase that produces long-term memory. New proteins forming synapses are produced and inserted into synapses. These changes incorporate new sensory information or modifications to motor actions into the circuit. This upgrading of synaptic sites can only occur if LTP modifications are turned-off by sleep. Thalamic relay nuclei cease to activate pyramidal cells due to the slowing of the EEG to 0.5 to 4 Hz during sleep. This blocks all sensory inputs, memories and motor instructions by activity in reticular thalamic nuclei and inhibition of pyramidal cell somata preventing intracortical responses. Brought to you by
  11. 11. MIND & EMOTION EMOTIONS are associated with specific visual images, (faces and locations), sounds and sensory-motor inputs by comparison with hippocampal templates for each sensory modality. The primary visual cortex has a major subcortical projection via the lingula to the parahippocampal gyrus and into the hippocampal perforant path. Images from the visual cortex are processed in the hippocampus for familiarity (friend or foe) and are then directed to the amygdala for determining fright or flightthrough autonomic expressions of eithere the sympathetic or parasympathetic systems. Conscious emotions are determined in the hippocampus and these project via the fornix to the hypothalamic mammary bodies. From here emotions are relayed via the anterior group nuclei of the thalamus to emotion storage in the cingulate cortex. The conscious MIND associates incoming sensory memories and motor events as comparisons to previous emotional responses of stored memories. Memories associated with high-emotion are most lasting and are easiest to recall. Brought to you by
  12. 12. MIND AND COGNITIONCOGNITION is the ability of the MIND to formulate “frameworks of understanding” from multiple sensory modalities, memory stores and integrative sensory centers like Wernicke’s areas. The MIND recalls memories of past experiences according to their emotions, related values, consequences of actions and passes them through the medial dorsal nucleus of thalamus to the pre-frontal cortex. Here, COGNITION assembles temporal and spatial order, and establishes meaning of yet, unrealized sensory inputs, memories, motor actions and their consequence into frameworks of understanding. The pyramidal circuitry of the frontal lobe generates COGNITION as a MIND state of understanding that represents the INTELLECT. Perceptions that are generated by COGNITION give the MIND the ability to extend understanding into PREDICTION. Fundamental to the cognitive process is the ability to IMAGINE that leads to development of VISION. The COGNITIVE capability of imagination and vision represent the creative breadth of the individuals INTELLECT. • The vast potential of Mind's ability to “imagine” meets limitations of the brain’s ability to control body actions beyond muscles, glands and hormones. Through creativity and ingenuity, the intellectual MIND engineers mechanical, chemical, electronic and nuclear devices that aid and by-pass “BRAIN-BODY” limitations. This ingenuity allows our limited motor capacity to capture and control vast energy sources to meet Mind's goals of far reaching imagination. Brought to you by
  13. 13. MIND AND BEHAVIOR The MIND’S power to reason, formulate cognition, and make decisions initiating motor actions are the bases of expressing behaviors and speech. However, much of behavior occurs from involuntary reflexes, conditioned reflexes and predefined patterned movements. Virtually, all behaviors are either hard-wired in reflex circuits or are programmed in basal ganglia during development. For the most part, the conscious MIND is the decision-maker for initiation of movement for willful simple motions or selection of patterned- motor responses from a repertoire of expressions defining behavior. The MIND uses consequence and pleasure principles to determine behavior selections. Once these reflexes are initiated, the behaviors play-out according to the program, so much so, they can be difficult to interrupt. Examples are laughing, crying, patterns of movement and emotional expression. The MIND can modulate the extent of some reflexes but not entirely prevent them. Brought to you by
  14. 14. Behavior continued Homeostatic reflexes control much of our basic survival behaviors that include respiratory, cardiac, GI and urinary function as well as fight or flight actions. The amygdala and hypothalamus, being the centers of reflexive control of emotions, are the primary areas of reflex based motivations. The hypothalamus distributes involuntary actions through the two opposed autonomic systems, sympathetic and parasympathetic. Willful behaviors are based on the need to fulfill food, sexual and self esteem desires. Motivations, generated by the conscious MIND arise from the limbic system while emotion related involuntary behaviors are expressed through basal ganglia and motor cortices. Willful motivations generated from the MIND originate from the emotion-cortex, the cingulate gyrus. These arrive from the hypothalamic mammillary bodies as projections to anterior group thalamic nuclei and then to the cingulate gyri. Brought to you by
  15. 15. MIND & MOTIVATION• Willful behaviors are based on the need to fulfill food, sexual and self esteem desires. Motivations, generated by the conscious MIND arise from the limbic pleasure centers while emotion related voluntary behaviors are expressed through basal ganglia and motor cortices. The hypothalamic mammillary bodies send projections to anterior group nuclei and then to the cingulate gyri. Willful motivations of the MIND come from emotions associated with action memories stored in the cingulate gyrus. Self-esteem reinforcement is the principle motivating factor for humanoids and is driven by a pleasure obtained intrinsic to the MIND. The MIND obtains this pleasure basically from itself through its own satisfactory decisions for actions. Yet the bulk of the reinforcement for motivation is received from others as acknowledgement, some being approval others disapproval. Fundamentally, the MIND is looking to the mother and peers for a recognition of their own existence. These sources expand rapidly at young ages so that careful balances must be considered for amount and kind. Teaching the individual to give proper recognition to others and develop healthy exchanges is the fundamental base for motovating positive behaviors. Brought to you by
  16. 16. BRAIN - BODY - MIND Brought to you by
  17. 17. MIND & DECISION-MAKING • The central role of MIND is intelligent decision-making for initiating actions carried out by patterned movements for behaviors including the generation of speech content. (Sensory driven reflexes have only limited control by the MIND). The willful intent of MIND initiates self-serving motor control for survival and reproduction. MIND initiated voluntary actions operate through programmed basal ganglial control in passage through the ventral lateral (VL) and ventral anterior (VA) thalamic nuclear relay gate to reach pre-motor and motor related cortices. • When the MIND is not operating such as during sleep or unconsciousness, all voluntary muscle controlled reflexes are quiescent. Nevertheless, homeostatic reflexes (involuntary) operate without the MIND. When cortical neurons become synchronously active, sensory awareness returns and the MIND initiates programmed complex sensory-motor reflexes. Most basic are eye movements and antigravity expression. Virtually, every action generated by basal ganglia (except ballistic) is due to circuits wired for modulation in real-time by incoming sensory signals to the cerebellum. Patterned movements form a repertoire of behaviors that must be selected, initiated or stopped by MIND decisions. Conditioning of the programmed behavior can modify MIND initiated voluntary actions that are programmed in basal ganglia. Brought to you by
  18. 18. MIND vs REFLEXES and PROGRAMMED BEHAVIORS • The nervous system operates in three fundamental domains: 1) reflex control organ, 2) control of programmed patterned movement and 3) generation of the conscious self, “The MIND”. The caudal part of the nervous system is, principally, sensory-motor organization that we commonly revere as reflexes. The peripheral nervous system, (spinal and cranial nerves) together with the spinal cord and brainstem consists of hardwired circuits driving motor operations that are activated by sensory inputs. Reflexes control movements, involuntarily, through voluntary controllable muscles (musculoskeletal system). • The rostral brain including the thalamus, basal ganglia and cortices contain centers for programmed motor control of patterned movements that are stored in basal ganglia. Many of these movement patterns are hardwired before birth and others are conditioned by experience. The cerebellum lies over the brainstem and receives sensory cranial and spinal nerve inputs as well as inputs from all cerebral cortices through the pons within the brainstem. The cerebellum provides detailed fineness for programmed movements using sensory inputs and cortical control. • The neocortex, together with the thalamus is the source of the MIND. Sensory inputs to cortices bring the MIND to consciousness and forms memories. The active MIND selects programmed movements and initiates: objective movements, behaviors and speech content. The MIND also incorporates emotion into memories as well as formulates frameworks of understanding that represent the intellect. The MIND has limited capacity to control programmed movement because of complexity. The MIND selects and initiates movements. Brought to you by
  19. 19. MIND & MOTOR CONTROL • The brain operates motor control, reflexively, through spinal nerves of the spinal cord and cranial nerves of the brainstem and as movement patterns that are programmed in basal ganglia. The MIND's major role is to make conscious decisions for initiating behavior, speech-content and specific movements. In addition, the MIND can consciously modulate or subdue some reflex activity but can not totally stop reflexes. • Furthermore, the MIND is involved in training basal ganglial patterned- movements by conscious trials and observing their consequence. We observe and instruct our voluntary movement initiation across single joints or group actions in a conscious manner. This method is used to improve precision or increase speed and effectiveness. There are two types of MIND-initiated patterned- movements: One is modifiable patterned movement and the other is ballistic movements; both are programmed in the basal ganglia. Brought to you by
  20. 20. PROGRAMMED MOVEMENT• Modifiable patterned movements from basal ganglia are slower than ballistic movements and allow updating of sensory status to the cerebellar cortex and to the basal ganglial pattern generator during movement. These patterned movements are from a repertoire that can be initiated and stopped by the MIND or changes being made by MIND-decision during their execution. These patterns play-out from basal ganglia and are being optimized, continually, for agonist/antagonist muscle tone by the cerebellum in order to enhance fine control of movements. • In normal behaviors, the MIND does not control detail of movement but only the selection and the initiation of movement patterns. These behaviors are programmed using pre-wired reflexes, conditioned reflexes but can be modified by learning during development and young adults and are not changed much after adulthood is reached. Brought to you by
  21. 21. Basal Ganglia Patterned Movement & Cerebellar Control (Indirect pathway) The cerebellar cortex with pontine inputs from cerebral cortex and from sensory inputs to the cerebellar granule cell system provide ongoing agonist/antagonist tone control through projections of inhibitory PC’s to cerebellar nuclei producing excitatory inputs to VA & VL relay nuclear cells to balance globus pallidus inhibition of the indirect pathway. The effect is B.G. generated patterned-movement with cerebellar control. Cortical inputs to the indirect pathway come from the premotor cortex. These excitatory afferents synapse on inhibitory striatal neurons of the matrix containing enkephalin modulatory receptors. The matrix neurons project inhibition on neurons of the external segment of globus pallidus which has it’s main output to the subthalamic nucleus and is also inhibitory. The excitatory response of the subthalamic N. is excitatory onto the internal segment of GP. The internal segment of GP is inhibitory to the motor thalamus (VA & VL). These inhibitory inputs to VA & VL (relay nuclei) are modulated by cerebellar nuclear excitatory outputs and the integrated responses are temporally released to the premotor cortex by thalamic gating. ASSOCIATION CORTEX Frontal, Parietal, Temporal, Occipital & Limbic Striatum Matrix Enkephalin PONS Premotor - Sensori-Motor Cortex Globus Pallidus external Internal Cerebellar Granule cell to PCs Thalamus Cbl Nuc Lat.CorticospinalTr. Sup.CerebellarPeduncle Middle Cerebellar Peduncle CerebralPeduncles Subthalamic Nucleus S. Nigra Compacta Sp.Cord VA VL INDIRECT BASAL GANGLIAL PATHWAY = MODIFYABLE PATTERNED MOVEMENTS MOSSY FIBERS Brought to you by
  22. 22. BALLISTIC MOVEMENTS Ballistic movements are programmed in the basal ganglia to provide high speed and up to maximal strength. Ballistic movements are mostly selected for execution by the MIND. These movements can not be modified by the pattern generator or cerebellar control after initiation by the MIND (e.g. golf swing). Also, ballistic movements have associated non-ballistic movements that form a skeletal platform adjusting for the ballistic outcome. Examples are batting a baseball from a high speed pitch. The swing is ballistic but the knees raise or lower to adjust the height of the swing-platform in order to meet the ball. Programming is done by trial and error using sensory feedback, consequence of action and suggestions from extrinsic observers(coach) to encourage changes in specific types of actions. Cerebellar control during ballism is limited but must participate in releasing tone of antagonistic muscles that are actively tonic at the beginning the movement. This important function is described in the relationship between basal ganglial and cerebellar control. Brought to you by
  23. 23. Ballistic Movement Generation (Direct pathway). Cortical inputs to basal ganglia come from the premotor cortex. These afferents synapse on inhibitory striatal neurons in substance “P” patches of the striatum. Dopamine of substantia nigra compacta upregulates these inhibitory neurons increasing striatal inhibitory output to the internal segment of the globus pallidus (GPi) & substantia nigra reticulata (SNr). The output is inhibition to the motor thalamus (VA & VL) and excitation of these neurons by cerebellar nuclei. The integrative result is ballistic motor output to agonist muscles through premotor & motor cortices. The cerebellar granule cell activation of PC’s is too slow for ballistic movement so that these actions are interceded by antagonist related high speed climbing fiber input that activates PCs to inhibit cerebellar nuclei that release antagonist muscle tone. The effect is that dys-inhibition of GPi by striatal output results in patterned movements without control from sensory input modulation or from the cerebellar cortex. Thus, ballistic movement patterns are unchecked by the subthalamus (See indirect pathway). The movement pattern is preset for ballistic movements by motor cortex driving agonist motor neurons of the cord or brainstem and antagonist muscle relaxation from cerebellar tone production that is controlled by cerebellar nuclear outflow. The inhibitory output of the globus pallidus meets cerebellar nuclear excitation in VA & VL and these are gated to the premotor and motor cortex. The cerebellar nuclei for antagonist tone are controlled by climbing fiber activation of Purkinje cells. Striatum Patches Subt "P" INFERIOR OLIVE Premotor - Sensori-Motor Cortex Globus Pallidus Internal Substantia Nigra Reticulata Cerebellar Purkinje Cells Thalamus Cbl Nuc Lat.CorticospinalTr. Sup.CerebellarPeduncle CerebralPeduncles Subs Nigra Compacta VA VL Sp.Cord DIRECT BASAL GANGLIAL PATHWAY BALLISTIC PATTERNED MOVEMENT CLIMBING FIBERS FORAGONISTMUSCLES FORANTAGONISTICMUSCLES Brought to you by
  24. 24. SOURCE OF THE MIND The emergence of the conscious MIND out-of functional circuitry is based on input gating to four neocortical regions from the THALAMUS. Pyramidal cells and cortical circuitry are synchronously-phased across regions of the neocortex by four inter-linked thalamic-relay timing gates. EEGs are remote- recorded potentials from the cranial-surface showing a spindle marker potential appearing every second to 26- 28 milliseconds (at 40 Hz). The marker signals partition EEGs that are followed by high frequency signals (see Gerber et al. 2008). During cognition, the rate is 40 Hz while during sleep, the reticular thalamic nuclei slow thalamic outputs to 0.5-4 Hz. MEG’s indicate that the 40 Hz signal is also present during sleep (Llinas & Ribary 1993) and suggest that eye movements are being replayed for visual memory consolidation during REM sleep. EEG’s, MEG’s ERP’s and local depth electrodes reveal a second larger amplitude signal, “event-related-potentials”. These extend across the neocortex and reoccur after stimuli at latencies of 300-600 milliseconds. These appear to be the true signals of cognition and decision-making. Brought to you by
  25. 25. INPUTS FORMING MINDThe thalamus acts as the gate-keeper of outputs from thalamic relay nuclei to respective cortical regions. Sensory inputs from spinal and cranial nerves project to sensory thalamic relay nuclei (VP) and are gated by laterally placed reticular thalamic nuclei (RN). The RN act as the clocking timer for all cerebral inputs. Motor actions are initiated by MIND decision from pre-motor cortex onto the basal ganglia (BG) and cerebellum and then to the VA-VL of thalamus for interpolation with cerebellar control. Motor gating by synchronization of the VA-VL connections to motor cortices signal spinal and cranial motor neurons. The anterior group (AG) incorporates emotion into memories while the medial dorsal (MD) thalamus carries sensory attention, memories, emotion and motor responses into frontal and parietal lobes for formulation of understanding by the COGNITIVE MIND. Brought to you by
  26. 26. THALAMUS: GATEWAY TO CORTEXThe THALAMUS has four distinct relay functional regions that project to respective cerebral cortical regions. The caudal thalamus projects sensory inputs, arising from various types of receptors, i.e. vision, audition, touch, pain etc.. The motor thalami (ventral lateral and anterior lateral nuclei) are relay gating- nuclei for signaling motor behaviors and speech that are generated from basal ganglia and the cerebellum. Sensory inputs pass from primary sensory cortices through the hippocampus determining “friend or foe” and applies “fight or flight” reflexes through the hypothalamus. Also, the hippocampus projects signals to the anterior-group relay nuclei incorporating and storing emotion- linked memories in emotion-cortex. A fourth thalamic nuclear region is the medial thalamus that carries inputs for cognition. This relay nucleus projects to prefrontal cortex producing frameworks of understanding that give rise to intellect. The MIND emanates as consciousness and intellect arising from phased-synchronous activity across the four target regions of the neocortex. Brought to you by
  27. 27. THALAMIC-GATING The thalamus temporally blocks relay nuclei passage of sensory, motor, emotion and cognitive signals to the cerebral cortex during sleep (EEG frequencies below 5 Hz). Blocking of cortical inputs during sleep stops sensory and motor activity in order to prevent interruption of memory updating. In addition, extensor motor expression (standing) is blocked to prevent walking and injury during sleep. On awakening, the reticular thalamic nuclei increase the gating rate from 5-13 Hz. The thalamic relay nuclei of input gates “spike-train snippets”, briefly to respective cortices within each EEG cycle. At 40 Hz (cognitive), “event related potentials” (ERP’s, Miller et.al 2008 & MEG’s, Llinas & Ribary 1993) show a phased-synchrony of EEG’s and MEG’s over the cranium. This phasing appears to be due to the cascade of heirarchy from sensory input, emotion, cognition to motor decision making for selection and initiation of movement.Brought to you by
  28. 28. SOURCE OF GATING The reticular thalamic nucleus cups the lateral surface of the thalamus and sends projections, radially, into each of the thalamic relay nuclei. The close association and coupling of the reticular neurons are ideally positioned for synchronized release of relay nuclei firing to the cortex. Functional activity of reticular neurons synchronize the inhibitory gate on relay neurons slowing bursts to as little as one per second during sleep but to 15 to 40 Hz in the awake to cognitive individual. An other group of neurons, intralaminar thalamic nuclei, are distributed along the rostral-caudal circumference of the thalamus that is marked by an internal medullary lamina. Different laminar groups appear to projection to specific regions of the cerebral cortex. These afferents target the most distal, dendritic terminals of pyramidal cell dendrites in layer I. We propose that this intralaminar input is excitatory to pyramidal cells resulting in total depolarization of the the entire dendritic arbor by activating voltage sensitive calcium channels. The result is a short barrage of dendritic spikes (similar to climbing fiber-Purkinje cell responses) and that these correspond to spindles of the EEG and marks the beginning of the relay input. Following the total dendritic depolarization there is a coordinated re-polarization of pyramidal cells creating synchrony of equal resting potential levels throughout specific cortical region. Thus, all of the pyramidal cells begin to receive the relay barrage at the same time and thus produce a meaningful activity status in pyramidal cells to maximize the fidelity of pyramidal cell reception during subsequent thalamic relay inputs for 20 msec or so duration. Brought to you by
  29. 29. GATING BY THALAMIC RELAY NUCLEI All cortical inputs to the neocortex are gated within the temporal frame that represents cortical input passage through thalamic relay nuclei. The gate is controlled by the reticular thalamic nucleus (RT) as interval blocking and release of outputs of the relay nuclei to the neocortex. Intralaminar nuclei (black-blue) target pyramidal cells, we believe, sync these cortical neurons for receiving relay input. Relay nuclei for vision and audition are in the geniculate bodies while environmental and self sensations are relayed through the ventral posterior thalamus (VPL for body and VPM for head). Programmed motor control of basal ganglia are relayed by the ventral lateral (VL) and anterior (VA) nuclei. Emotions are relayed through the anterior group of nuclei while cognition is passed through the medial dorsal thalamic nuclei. DEH RETICULAR THALAMIC NUCLEUS MD VPLRT CEREBRAL CORTEX Anterior group CM AG MEDIAL DORSAL (MD) (VA) (VL) (VPM) (VPL) PULVINAR LGB RT Ventral Anterior Ventral Lateral Ventral Posterior Lateral Ventral Posterior Medial LATERAL GENICULATE BODY CM VPM MEDIAL INTRALAMINAR THALAMUS NUCLEi AFFERENT CORTICAL GATING BY THALAMUS RT RT SENSORY THALAMUS LGB MGB AG RETICULAR THALAMIC NUCLEUS RT Motor Sensory Emotion Cognition DorsalView Coronal View /` Motor Brought to you by
  30. 30. THALAMIC GATE & MIND The conscious MIND is an emergent state from operational cortical circuitry representing four major components. PRIMARY SENSORY MOTOR ASSOCIATION SENSORY MOTOR CORTICES LIMBIC HIPPOCAMPAL MEMORY MEDIAL DORSAL THALAMIC NUCSENSORY RELAY THALAMUS Pyramidal Cells ANTERIOR GROUP THALAMIC NUC FRONTAL WORKING MEMORY MIND MOTOR THALAMUS CORTICES RETICULAR THALAMIC NUCLEAR GATE INTRALAMINAR THALAMIC NUCLEI-- PYRAMIDAL CELL SYNCHRONIZATIONS SENSORY INPUTS BASAL GANG CERBELLUM INTEGRATED UNDERSTANDING HIPPOCAMPUS HYPOTHALAMUS EMOTIONCOGNITIONAWARENESS MOTOR DECISIONS Pyramidal Cells The four types of inputs at the bottom enter the relay thalamic nuclei, but are held by the reticular gate. The the pyramidal cells of the four cortical regions are receive inputs to the entire dendritic tree, In addition the most apical dendrites in layer one receive intralaminar inputs the temporal relation of the cascade in circuit processing gives rise to the MIND informational state. Brought to you by
  31. 31. ROLES OF MIND This summary shows, diagrammatically, how the characteristic components of MIND relate to functional expressions of motor actions. Consciousness of sensory inputs are processed into memory. Memories are associated with emotions that give values. A major role of the MIND is to make decisions of basal ganglial patterned movements that determine willful movements, behaviors and speech. PERSONALITY and INTELLECT emanate as products of MIND that reveal the individuality of SELF and cognitive capacity. Brought to you by
  32. 32. OVERVIEW The brain controls the body, unconsciously, through homeostatic reflexes. Voluntary movements for survival and reproduction are initiated by decision of the MIND. These decisions are for programmed behaviors determining actions and personality. The MIND is emergent from neuronal activity of the cerebral cortex signaling sensory awareness, consciousness and the power to reason. MIND’s experiences establish VALUES that become the basis of our personality, dictate our actions, and define the spirit of self. This SPIRIT transcends the active brain in the SOUL that is held in the MINDS of others & in antiquities. BRAIN MIND B O D Y REASON DECISIONS consciousness MEMORIES SOUL VALUES Hillman BRAIN & BODY MIND & SOUL Brought to you by
  33. 33. SIGNIFICANT REFERENCES • Basilis Zikopoulos1 and Helen Barbas Prefrontal Projections to the Thalamic Reticular Nucleus form a Unique Circuit for Attentional Mechanisms. The Journal of Neuroscience, 26(28):7348 – 7361 2006 • Brian T. Miller , Leon Y. Deouell, Cathrine Dam, Robert T. Knight, Mark D'Esposito Spatio-⁎ temporal dynamics of neural mechanisms underlying component operations in working memory Brain Research 1206: 61- 75 2008 • Gerber, P et. al., Interobserver agreement in interpretation of EEG patterns . . . . J. Clin NeuroPhys 25: 241-249 2008. • http://en.wikibooks.org/wiki/Consciousness_studies • Long, M.A. et al. Small clusters of electrically coupled neurons generate synchronous rhythms in the thalamic reticular nucleus. J. Neurosci. 24, 341–349 (2004) • Migno, E Why We Sleep: The Temporal Organization of Recovery. PLoS Biology 6:0661-669 (2008) www.plosbiology.org • Pablo Fuentealba, Igor Timofeev, and Mircea Steriade Prolonged hyperpolarizing potentials precede spindle oscillations in the thalamic reticular nucleus PNAS 101 9816-9821 2004 • Pablo Fuentealba, Mircea Steriade The reticular nucleus revisited: Intrinsic and network properties • of a thalamic pacemaker. Progress in Neurobiology 75 (2005) 125–141 • Llinas,R, , Ribary, U (1993) Coherent 40-Hz oscillations characterizes dream state in humans. Proc. Natl. Acad. Sci. USA 90:2078-2081 • Steriade, M. et al. The deafferented reticular thalamic nucleus generates spindle rhythmicity. J. Neurophysiol. 57, 260–27 (1987) • Zhang, L and Jones, EG. Corticothalamic inhibition in the thalamic reticular nucleus. J Neurophysiol 91: 759–766, 2004. Brought to you by
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