Philosophy, Psychology and Informatics Group. 04/03/09

Transcription

1 Philosophy, Psychology and Informatics Group 04/03/09 1

2 The biological basis of cognitive control from the immune, endocrine, or central nervous system? BEYOND NEUROTRANSMISSION JOURNAL CLUB - 05/02/09 2

3 Aims To introduce an example of cognition outside the brain. To discuss the biological mechanisms involved To show how these mechanisms might be used as the basis for a model of mind that is not purely in the head. 3

4 Cognitive control : definitions We define cognitive control as the ability to flexibly adapt behavior to current demands, by promoting task-relevant information and behaviors over temporally-extended periods and in the face of interference or competition. This ability is central to most higher cognitive functions, and contributes to the unique character of human behavior. 4

5 Cognitive control : definitions We define cognitive control as the ability to flexibly adapt behavior to current demands, by promoting task-relevant information and behaviors over temporally-extended periods and in the face of interference or competition. This ability is central to most higher cognitive functions, and contributes to the unique character of human behavior. Executive functions - Broadbent (1950), automatic + controlled processes - Baddeley s central executive - Who is the executive? Is sense of self important? 4

6 Cognitive control : definitions We define cognitive control as the ability to flexibly adapt behavior to current demands, by promoting task-relevant information and behaviors over temporally-extended periods and in the face of interference or competition. This ability is central to most higher cognitive functions, and contributes to the unique character of human behavior. Executive functions - Broadbent (1950), automatic + controlled processes - Baddeley s central executive - Who is the executive? Is sense of self important? Decision making 4

7 The prefrontal cortex 5

8 The prefrontal cortex Neuropsychology 5

9 The prefrontal cortex Neuropsychology Evidence from fmri, TMS 5

10 The prefrontal cortex Neuropsychology Evidence from fmri, TMS Miller & Cohen - the function of the PFC is cognitive control 5

11 The prefrontal cortex Neuropsychology Evidence from fmri, TMS Miller & Cohen - the function of the PFC is cognitive control At the biological level, our work focuses on the functions of prefrontal cortex and anterior cingulate, and their regulation by brainstem neuromodulatory systems, such as those using the neurotransmitters dopamine and norepinephrine... 5

12 The prefrontal cortex Neuropsychology Evidence from fmri, TMS Miller & Cohen - the function of the PFC is cognitive control At the biological level, our work focuses on the functions of prefrontal cortex and anterior cingulate, and their regulation by brainstem neuromodulatory systems, such as those using the neurotransmitters dopamine and norepinephrine... More recently : Dopamine, neuromodulation 5

13 Parasitic manipulation - An example of control? 6

14 Parasitic manipulation - An example of control? 6

15 How might parasites control their hosts? 7

16 How might parasites control their hosts? Neurotransmitters 7

17 How might parasites control their hosts? Neurotransmitters Neuromodulation 7

18 How might parasites control their hosts? Neurotransmitters Neuromodulation Gene expression 7

19 How might parasites control their hosts? Neurotransmitters Neuromodulation Gene expression Neuroendocrine changes 7

20 How might parasites control their hosts? Neurotransmitters Neuromodulation Gene expression Neuroendocrine changes Immune perturbation 7

21 How might parasites control their hosts? Neurotransmitters Neuromodulation Gene expression Neuroendocrine changes Immune perturbation Which are mechanisms, and which are measurables? 7

22 Is the parasite truly in control? 8

23 Is the parasite truly in control? Is the parasite conscious and in control? 8

24 Is the parasite truly in control? Is the parasite conscious and in control? Has the parasite usurped the host s conscious control? 8

25 Is the parasite truly in control? Is the parasite conscious and in control? Has the parasite usurped the host s conscious control? Or is the parasite merely triggering existing behavioural programs without any real sense of control? 8

26 The quality of control? 9

27 The quality of control? 9

28 Examples 10

29 Examples Parasitic wasp Polymorphous paradoxus Trematode 10

30 Examples Parasitic wasp Polymorphous paradoxus Trematode In at least two of three of these examples, it appears that the host, not the parasite produces the neuromodulators that alter host behaviour. Parasites may induce the host s immune system to produce the appropriate neuromodulators. Adamo (2002) 10

31 Examples Parasitic wasp Polymorphous paradoxus Trematode In at least two of three of these examples, it appears that the host, not the parasite produces the neuromodulators that alter host behaviour. Parasites may induce the host s immune system to produce the appropriate neuromodulators. Adamo (2002) IS THE PARASITE CONTROLLING THE HOST USING THE IMMUNE SYSTEM? 10

32 Where is the locus of control? 11

33 Where is the locus of control? The brain 11

34 Where is the locus of control? The brain The immune system 11

35 Where is the locus of control? The brain The immune system Both 11

36 Where is the locus of control? The brain The immune system Both Neither 11

37 How should we model/explain control? What components are needed in a model of decision making? What components are in existing models? Is it reasonable to view control as a purely neural process occurring in the brain? 12

38 Who is controlling the ant? 13

39 Who is controlling the ant? If the immune system functionally defines self... 13

40 Who is controlling the ant? If the immune system functionally defines self......immune perturbation leads to loss of selfcontrol... 13

41 Who is controlling the ant? If the immune system functionally defines self......immune perturbation leads to loss of selfcontrol......and in the process the immune system redefines the self in terms of the needs of the parasite 13

42 The immune brain Examples show pathological cases, but immune, brain, and endocrine systems are in constant interaction in healthy individuals. Are similar processes occurring in physiological conditions? Cognitive control via neural computation Cognitive control via assertion of the self? 14

43 Intermission Outline cases where the immune system and brain are functionally interacting Offer an account of how these interactions might support an immune-centric view of cognition. 15

44 The immune brain : examples Ader and Cohen (1975) - The immune system can be classically conditioned by CNS stimuli A single pairing between a CNS and an immune stimuli can result in the CNS stimuli alone triggering an immune response 16

45 The immune brain : examples Cytokines produced during an immune response can modulate synaptic plasticity cytokines can effect release of hormones, modulators and transmitters in the brain 17

46 The immune brain : examples 18

47 The immune brain : examples animals and people with a proactive coping style also display higher HPA activity - Hawks and Doves 18

48 The immune brain : examples animals and people with a proactive coping style also display higher HPA activity - Hawks and Doves hyperdopaminergic rats show increased HPA activity, whilst hypodopaminergic rats show increased susceptibility to autoimmune disease. Kavelaars et al (1997) 18

49 The immune brain : examples animals and people with a proactive coping style also display higher HPA activity - Hawks and Doves hyperdopaminergic rats show increased HPA activity, whilst hypodopaminergic rats show increased susceptibility to autoimmune disease. Kavelaars et al (1997) behavioural patterns of wild-type rats can be used to predict susceptibility to autoimmune disease. Kavelaars et al (1999) 18

50 The immune brain : examples animals and people with a proactive coping style also display higher HPA activity - Hawks and Doves hyperdopaminergic rats show increased HPA activity, whilst hypodopaminergic rats show increased susceptibility to autoimmune disease. Kavelaars et al (1997) behavioural patterns of wild-type rats can be used to predict susceptibility to autoimmune disease. Kavelaars et al (1999) Do personality and immunity emerge from a shared root? 18

51 The immune brain : A sketch 19

52 The immune brain : A sketch 50-90% (?!?) of cells in the brain are glial cells 19

53 The immune brain : A sketch 50-90% (?!?) of cells in the brain are glial cells Our models of the nervous system typically assume that neurons alone are capable of causing actions, representing mental states, and learning, while glial cells act in a supporting role. 19

54 The immune brain : A sketch 50-90% (?!?) of cells in the brain are glial cells Our models of the nervous system typically assume that neurons alone are capable of causing actions, representing mental states, and learning, while glial cells act in a supporting role. Microglia (15% of the brain) are the brain s macrophages and are capable of producing and responding to cytokines Glial cells metabolise glutamate and many other transmitters required for neurons to function 19

55 The immune brain : A sketch 20

56 The immune brain : A sketch Neuron : Glia relationship = Mother : Child? By controlling neural metabolism glial cells set constraints for self(ish) behaviour 20

57 The immune brain : A sketch Neuron : Glia relationship = Mother : Child? By controlling neural metabolism glial cells set constraints for self(ish) behaviour Neurons are rarely able to act in a way that compromises the integrity of the self. in this sense the co-ordinated activity of the brain and body can be seen as the result of an assertion of self. if the immune system defines the immune self, does the immune brain define the cognitive self? 20

58 Parasites take control of the self 21

59 Parasites take control of the self In the case of the parasites 21

60 Parasites take control of the self In the case of the parasites parasites aim to take over the host s self 21

61 Parasites take control of the self In the case of the parasites parasites aim to take over the host s self evolution have shown the most direct way to do this - by secreting immunomodulators which perturb the biological sense of self 21

62 Parasites take control of the self In the case of the parasites parasites aim to take over the host s self evolution have shown the most direct way to do this - by secreting immunomodulators which perturb the biological sense of self in taking control of the self, the host organism begins to secret cytokines, then hormones, then neuromodulators which effectively change the constraints for what constitutes self(ish) behaviour 21

63 The immune brain model 22

64 The immune brain model offers a different perspective on brain function from the computationalist account 22

65 The immune brain model offers a different perspective on brain function from the computationalist account provides an account of behaviour which is inherently integrated with the body 22

66 The immune brain model offers a different perspective on brain function from the computationalist account provides an account of behaviour which is inherently integrated with the body The metaphor of self assertion and identity is psychologically interesting and potentially more useful in clinical or therapeutic settings. 22

67 The immune brain model offers a different perspective on brain function from the computationalist account provides an account of behaviour which is inherently integrated with the body The metaphor of self assertion and identity is psychologically interesting and potentially more useful in clinical or therapeutic settings. opens up the possibility of relating a scientific understanding of the brain and of identity to philosophical debate + vice versa. 22

68 Summary processes such as cognitive control can have their genesis outside the CNS It is possible to develop a scientific account of the mind which is not restricted to the central nervous system interactions and cooperation between the immune system and brain offer an avenue for understanding the body:brain relationship the concept of self as it has been used in immunology has great potential as a metaphor for understanding the biological basis of the cognitive self 23

69 questions... 24