Combined effects of alcohol and caffeine on the late components of the event-related potential and on reaction time. Introduction.

Transcription

1 P100 P200 P300 Combined effects of alcohol and caffeine on the late components of the event-related potential and on reaction time N100 N200 Late components Frances Heritage Martin Joshua Garfield 1 Biological Psychology (2005) 2 Caffeine and alcohol are the most commonly consumed drugs in the world. Caffeine + alcohol antagonism (Moskowitz and Burns, 1981) 3 4 Study of the combined effects on ERPs determine what stages of processing are involved in the antagonism between the effects of these drugs on RT. This study is concerned with the P200, N200, P300 and N500 components of the event-related potential (ERP). 5 P200 amplitude is affected by attention allocation (Wolach and Pratt, 2001) N200 indicate index selection of relevant stimuli orientation to relevant stimuli for further conscious processing (Loristet al., 1996, 1995). 6

2 P300 schema updating (Donchin,1981) or attention allocation (Isreal et al., 1980) P300 amplitude is proportional to subjective importance of a stimulus (Pritchard, 1981) and cortical arousal (Ruijter et al., 2000). Caffeine stimulates the whole cortex (Sawyer et al., 1982) Believed that it actions at adenosine receptor (A 1,A 2 and A 3 ) Averaged ERP of CRT- Averaged ERP of SRT = N caffeine Adenosine DA antagonist in striatum GABAergic activity in striatum In the cortex caffeine activity of glutamate (adenosine receptor blocker) (Dohrman et al., 1997) overall activation of cortical motor areas 9 10 Caffeine is a weak blocker of A 1 and A 2 receptors Waking, arousal and attention (Feldman et al., 1997) 11 Caffeine mg/kg have been found to shorten simple RT.(Hasenfratz et al., 1993; Moskowitz and Burns, 1981;Sawyer et al., 1982) Other studies have failed to find an effect of caffeine on simple RT.(Franks et al., 1975; Liguori and Robinson, 2001) Caffeine mg had no significant effect on choice RT. (Franks et al., 1975; Liguori and Robinson, 2001; Nuotto et al.,1982) 12

3 Effects of caffeine on ERPs Caffeine 250 mg P300 amplitude (Lorist et al., 1994, 1995; Ruijter et al., 2000). Caffeine P300 latency in older (but not younger participants) (Lorist et al., 1995) Effects of alcohol on ERPs Alcohol lengthens N200 and P300 latency for both visual and auditory stimuli. At a dose of 0.75 ml/kg alcohol, these effects on P300 amplitude and latency have been found as late at 4 hr postingestion (Schuckitetal., 1988) Nuotto et al.(1982 ) alcohol at high doses ( g/kg) had no effect on choice RT. Alcohol appears to act as an adenosine agonist, inhibiting uptake of adenosine in the brain (Dohrman et al., 1997). In tissue isolated from the hippocampus, adenosine antagonists have been found to prevent alcohol s inhibitory effect on cells (Dar et al., 1983) Research question Can caffeine reverse deterioration effect of alcohol on ERPs and reaction times? They expected that Alcohol N200,P300 latency P300,N500 amplitude Caffeine P300 latency P200,P300,N500amplitude SRT Alcohol+Caffine N200,P300 latency (from alcohol) P300,N500 amplitude (from alcohol) 17 18

4 Participants (Inclusion criteria) 16 females participated Mean age was 24 yrs (18 43 yrs, S.D. = 7) Mean weight was 67 kg. (S.D. = 12) Mean daily caffeine consumption =153 mg (0-600 mg., S.D. = 164) Mean weekly alcohol intake = 3.2 standard drinks (0-10 standard drinks, S.D. = 2.9) Participants (Exclusion criteria) phenylketonuria neurological disorders brain damage pregnancy panic disorder Participants (exclusion criteria) allergy to caffeine or alcohol binge drinking of more than 8 standard drinks in1sitting smoking of more than 4 cigarettes per week physical illness Participants were asked to abstain from food for 4 h, caffeine for 12 h, alcohol for 24 h, and any other mind-altering drugs for 48 h prior to each testing session Apparatus 23 24

5 Procedure Each participant took part in 4 experimental sessions Double placebo( 2 equal artificial sweetener tablets) Alcohol(0.7ml alcohol/kg+orange juice+0.01 ml/kg peppermint water concentrate) Caffeine (2 No-Doz Awakeners tablets,each contains 100 mg.caffeine) Double-drug (alcohol + caffeine) 25 Procedure Participants were blind to condition and session order was randomised. Session starting times for each participant were separatedbyatleast24h. Mean session starting time =2.02 pm. (range am pm.) Blood alcohol concentration (BAC) was measured with a Lion Alcometer S-D2 breathalyser 26 Procedure Read an information sheet completed an informed consent form test BAC BAC>0.05 mg/dl asked to remain in the lab Test BAC at half hour intervals 2 pills+water test BAC till below 0.05 mg./dl Test again 5 min later if it remain<0.05mg/dl,participants were permitted to leave min 2SRT+2CRT test BAC 27 Response keypad A F X Z P 28 Simple Reaction Time XZ hold down the central button while Xs appeared Decision time Choice Reaction Time XZXPXFXA Movement time 29 30

6 Procedure EEG was recorded continuously at 500 Hz and filtered with a bandpass of Hz. Eye blinks were detected in the vertical electro-oculogram channel. Ocular artifact reduction,using the eye movement reduction algorithm of the Neuroscan 4.1 edit program, was applied where blinks were found Procedure EEG data were then epoched from 100 ms prestimulus to 900 ms post-stimulus. Averaged epochs were then filtered with a bandpass of Hz P200 the maximum positive-going peak in the epoch ms. post- stimulus onset. N200 the maximum negative-going going peak in the epoch ms. P300 the maximum positive going peak in ms. N500 the maximum negative going peak in the epoch ms. 33 Design and data analysis This study was a 2x2x2 within subjects blind design. Independent variables were caffeine 200 mg placebo alcohol 0.7 g/kg placebo complexity SRT CRT 34 Design and data analysis Dependent measures were latency and amplitude of the P200, N200, P300 and N500, decision time and movement time. Data were analysed with repeated measures analyses of variance A significance level of p <0.05 after Greenhouse Geisser correction was used

7 Result Blood alcohol concentration (BAC) Caffeine did not have a significant effect on BAC,F(1,15)=1.3,p>0.05 Time did have a significant effect on BAC,F(1,15)=12.4,p<0.01 There was no significant interaction between time and caffeine,f(1,15)=0.007,p>0.05 Result Behavioral data Accuracy (SRT) Out of a total 168 non-target presentations,mean number of false alarm was 0.48 or 0.3% Of 32 target presentations,mean number of misses was 0.49 or 1.5% Result Behavioral data Accuracy (CRT) A mean of 0.83 responses,2.6% of 32 possible responses in the CRT were incorrect Incorrect response rates were not significantly affected by either caffeine or alcohol,or by an interaction of drugs Result Behavioral data Decision time Alcohol No alcohol SRT DT(ms) CRT ** DT(ms) SRT CRT Alcohol 530* No alcohol Result Behavioral data Decision time DT (ms) Result Behavioral data Movement time Task was the only variable to have a significant effect on MT,F(1,15)=84.8,p<0.001 Caffeine No caffeine SRT X X CRT 575*

8 43 44 SRT when no caffeine SRT when no caffeine SRT when have caffeine CRT when no caffeine CRT when no caffeine CRT when have caffeine SRT when have caffeine CRT when have caffeine SRT when have alcohol N500 when have alcohol CRT when no alcohol N500 when no alcohol SRT when no alcohol CRT when have alcohol* 47 48

9 Predictions that alcohol would slow RT and the latency of both P200 and P300 components were confirmed. Alcohol DT, P200 and P300 latency in both CRT and SRT task Jaaskelainen et al. (1996), the latency of the P100 and N100 are relatively insensitive to the effects of alcohol N200 amplitude by alcohol suggests that brain s capacity for selection of relevant stimuli for further conscious processing. P300 amplitude in parietal region by alcohol but Jaaskelainen et al., 1996 found that alcohol reduces P300 amplitude Studies employing a greater range of alcohol dosage levels, larger participant samples, and a greater range of task demand on working memory could clarify the nature of our findings Previous studies found that caffeine CRT but not SRT (Lorist et al., 1994; Smith et al., 1977), in this experiment Caffeine CRT but not SRT and DT 53 SRT task lasted less than 10 min it may not have had sufficient potential to elicit lapses of attention to allow caffeine s effects on attention to be relevant to this task. Further investigation into possible differences in caffeine s effects on long and short duration simple RT tasks would help clarify this issue. 54

10 caffeine CDT but not CMT Caffeine P300 latency in CRT support Lorist et al. (1994), Suggest that caffeine speeds up response output, but not central processing. suggests that caffeine speeds up a central decision process. related to caffeine s role as a dopamine agonist in the striato-pallidal pathways leads to increased activity in areas of the brain related to cognitive aspects of motor programming. (Zahniseretal., 2000) Previous studies P300 amplitude by caffeine arousal (Ruijter et al., 2000) raising the signal:noise ratio in the brain (Lorist et al., 1995) subjective difficulty of the task (Lorist et al., 1994). caffeine signal:noise ratio attributed to increased levels of NE resulting from blockade of adenosine receptors (Lorist et al.,1996) N500 can be considered to reflect processes specific to the CRT task. In the presence of alcohol, caffeine reduced N500 area at left hemisphere and frontal sites generally. Assuming that N500 is related to working memory processes, this suggests that the combination of alcohol and caffeine impaired working memory processes associated with left hemisphere and frontal areas of the brain

11 Thank You Happy Loy Krathong s Day Geisser-Greenhouse Greenhouse correction.. The Geisser- Greenhouse correction referred to in SPSS is another variant on the procedure described above under Huynh & Feldt.. A slightly different correction factor (epsilon) is computed, which corrects the degrees of freedom slightly more than the Huynh & Feldt correction. So, significance tests with this correction will be a little more conservative (higher p-value) p than those using the Huynh-Feldt correction Geisser-Greenhouse Greenhouse correction was used for repeated measures analysis to correct for violations of the sphericity assumption. Adenosine slows tachycardias associated with the AV node via modulation of the autonomic nervous system without causing negative inotropic effects. It acts directly on sinus pacemaker cells and vagal nerve terminals to decrease chronotropic and dromotropic activity. Adenosine is the drug of choice for paroxysmal supraventricular tachvcardia (PSVT) and can be used diagnostically for stable, wide complex tachyardias of unknown type after two doses of lidocaine

12 signal-to to-noise ratio In analog and digital communications, signal-to to- noise ratio, often written S/N S N or SNR, is a measure of signal strength relative to background noise.. The ratio is usually measured in decibels (db). If the incoming signal strength in microvolts is Vs,, and the noise level, also in microvolts, is Vn, V then the signal-to to-noise ratio, S/N, in decibels is given by the formula S/N = 20 log10 10(Vs/Vn) If Vs V = Vn, V, then S/N = 0. In this situation, the signal borders on unreadable, because the noise level severely competes with it. In digital communications, this will probably cause a reduction in data speed because of frequent errors that require the source (transmitting) computer or terminal to resend some packets of data Ideally, Vs is greater than Vn, V, so S/N is positive. As an example, suppose that Vs V = 10.0 microvolts and Vn = 1.00 microvolt. Then S/N = 20 log10 10(10.0) = 20.0 db which results in the signal being clearly readable. If the signal is much weaker but still above the noise -- say 1.30 microvolts -- then S/N = 20 log10 10(1.30) = 2.28 db which is a marginal situation. There might be some reduction in data speed under these conditions. If VsV is less than Vn, V, then S/N is negative. In this type of situation, reliable communication is generally not possible unless steps are taken to increase the signal level and/or decrease the noise level at the destination (receiving) computer or terminal